Synergy of Dendrites‐Impeded Atomic Clusters Dissociation and Side Reactions Suppressed Inert Interface Protection for Ultrastable Zn Anode

The sluggish ions‐transfer and inhomogeneous ions‐nucleation induce the formation of randomly oriented dendrites on Zn anode, while the chemical instability at anode–electrolyte interface triggers detrimental side reactions. Herein, this report in situ designs a multifunctional hybrid interphase of Bi/Bi2O3, for the first time resulting in a novel synergistic regulation mechanism involving: (i) chemically inert interface protection mechanism suppresses side reactions; and more fantastically, (ii) innovative thermodynamically favorable Zn atomic clusters dissociation mechanism impedes dendrites formation. Assisted by collaborative modulation behavior, the Zn@Bi/Bi2O3 symmetry cell delivers an ultrahigh cumulative plating capacity of 1.88 Ah cm−2 at 5 mA cm−2 and ultralong lifetimes of 300 h even at high current density and depth of discharge (10 mA cm−2, DODZn: 60%). Furthermore, under a low electrolyte‐to‐capacity ratio (E/C: 45 µL mAh−1) and negative‐to‐positive capacity ratio (N/P: 6.3), Zn@Bi/Bi2O3||MnO2 full‐cell exhibits a superior capacity retention of 86.7% after 500 cycles at 1 A g−1, which outperforms most existing interphases. The scaled‐up Zn@Bi/Bi2O3||MnO2 battery module (6 V, 1 Ah), combined with the photovoltaic panel, presents excellent renewable‐energy storage ability and long output lifetime (12 h). This work provides a fantastic synergistic mechanism to achieve the ultrastable Zn anode and can be greatly promised to apply it into other metal‐based batteries.


Introduction
Rechargeable aqueous Zn-ion batteries (RAZBs) are considered as a promising candidate for lithium-ion batteries, due to the dependable safety of nontoxic aqueous electrolytes and the unique merits of Zn anode, such as low price, relatively suitable redox potential, and high theoretical capacity. [1]Despite these attractive properties, Zn anode remains struggling with dendritic growth, hydrogen evolution reactions (HER), and interfacial corrosion (Scheme 1), which severely corrupt the Zn plating/stripping reversibility and chemical stability of anode-electrolyte interface. [2]o this end, tremendous strategies have been attempted to solve these issues aforementioned.Among them, constructing functional interphase is regarded as an engaging solution due to its convenience for the anode interface protection, where various interphase materials are summarized based on different modulation mechanisms.In the matter of dendrites repression: (i) redistribute ions flux and homogenizing nucleation sites through Scheme 1. Illustration of ions-deposition behavior and interfacial chemistry on bare Zn (upper) and Zn@Bi/Bi 2 O 3 electrode (down) during the cycling process.
heterometallic or organic interphases with numerous zincophilic components; [3] (ii) orientationally guide horizontal and dense Zn deposition through Zn(002) lattice-matching interphase. [4]With respect to HER alleviation: (i) buffer interfacial pH through reversible hydrogen-proton storage interphases; [5] (ii) constructure interfacial local hydrophobic environment through amphiphilic polymeric interphases. [6]espite the above multiscale regulation mechanism, this remains challenging to simultaneously satisfy interfacial chemical stability and fast ions-deposition kinetics, due to the high interfacial hydrophilicity or strong interfacial resistance endowed by these existing interphases.More notably, in terms of regulating deposition, most of previous interphases always concentrate on inducing the homogeneous migration/nucleation of numerous single Zn atoms via chemical interaction with own zincophilic heterogroups.Nevertheless, it is generally ignored that the distribution of inherent zincophilic active sites and Zn 2+ -conductive channels contained in these interphases gradually becomes nonuniform, as the fast and deep plating/stripping process under high current density or depth of discharge (DOD).Correspondingly, the above-mentioned directional atom-nucleation effect will be invalid, which still sparks the tip accumulation of mas-sive individual Zn adatoms on hotspots, thus inducing the formation of the large and irregularly distributed "atomic clusters" that enable evolve into dendrites.
Atomic clusters could be regarded as the metastable particles at a microscopic level produced under the nonequilibrium state. [7]Particularly noticing, the studies about the atomic clusters formed are able to provide a fundamental comprehension for the microscopic charge interaction, adsorptionmigration, or bonding-dissociation of every individual adatom on different substrate surfaces. [8]In the field of RAZBs, however frustratingly, related interphase design works that link the kinetic/thermodynamic behavior of atomic clusters to Zn deposition chemistry are still in the infancy.Therefore, it is urgent for deeply exploring the dynamic chemical interaction such as interatomic energies or surface electrons transfer between the as-designed interphase and nonplanar Zn atomic clusters during Zn crystallites formation, aiming to facilitate the uniform Zn deposition at more rigorous conditions.
Herein, we in situ design a multifunctional 3D composite interphase of Bi/Bi 2 O 3 on Zn anode, for the first time initiating a synergistic modulation mechanism: the innovative thermodynamically favorable Zn atomic clusters dissociation mechanism inhibiting dendrites formation and chemically inert interface protection mechanism alleviating interfacial side reactions (Scheme 1).Theoretical and experimental investigations verify this novel synergy mechanism.With respect to dendritesrefrained atomic clusters dissociation: there exists the low dissociation energy and weak electrons interaction between the large tip-type Zn atomic clusters and dominant Bi phase while atomic clusters themselves are thermodynamically unstable and more easily decomposed on both Bi and Bi 2 O 3 phases, which facilitate the dynamic movement and dissociation of large Zn atomic clusters, thus avoiding the further evolution of numerous Zn adatoms toward irregular protrusions.Thus, the uniform Zn deposition with 9 mAh cm −2 capacity is achieved even at 6 mA cm −2 .With respect to side reactions suppressed inert interface protection: the superb HER inhibition capability for Bi/Bi 2 O 3 is obtained relying on the much high Gibbs free energy of hydrogen adsorption (ΔG H ) and low onset HER overpotential mainly contributed by the Bi 2 O 3 phase.Meanwhile, appropriate hydrophobicity and high corrosion potential of Bi/Bi 2 O 3 interphase endow it with prominent against corrosion ability.Benefiting from above synergistic regulation, Zn@Bi/Bi 2 O 3 electrode exhibits remarkably prominent cyclic performance no matter in symmetry cells system or practical full-cells system.Impressively, the enlarged battery module with Zn@Bi/Bi 2 O 3 electrode at Ah-leveled capacity exhibit the high potential and feasibility as energy-storage device for renewable energy source.

Structural Characterization and Physicochemical Features Investigation
The in situ growth of Bi/Bi 2 O 3 interphase on commercial Zn foil by synchronous redox reaction and self-assembling process (Figure S1, Supporting Information).X-ray diffraction (XRD) patterns in Figure 1a clearly manifest the additional characteristic peaks of hexagonal Bi phase (PDF#44-1246) and monoclinic -Bi 2 O 3 phase (PDF#76-1730) on the Zn@Bi/Bi 2 O 3 electrode, in comparison with bare Zn.The corresponding crystal planes of Bi and Bi 2 O 3 phases are further presented in the small built-in diagram, including representative (003), (012), (104), (110) planes of Bi and (211), (200) planes of Bi 2 O 3 .Interestingly, compared to other crystal planes, the Bi (012) crystal plane presents larger full width at half maximum (FWHM).The larger FWHM () of Bi (012) plane represents its smaller average thickness, that is the larger exposed area in the Bi crystal phase [9] Nevertheless, the diffraction peaks of Zn x Bi 1-x alloy phase are not discovered in XRD patterns, due to the extreme difficulty of alloying reaction between Zn and Bi at room temperature (binary diagram: Zn x Bi 1-x ).Subsequently, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) is employed to further disclose the chemical components of as-designed interphase.Figure 1b shows that the two typical Raman peaks at 71 and 93 cm −1 are corresponding respectively to the E g and A 1g stretching models of Bi-Bi bonds in the inner Bi phase. [10]Meanwhile, some other characteristic peaks with a wide distribution of Raman shift, ranging from 100 to 500 cm −1 regions, can be assigned to the stretching vibrations of Bi-O-Bi configuration in the outmost Bi 2 O 3 phase. [11]In addition, for the characterization of the XPS spectrum, the high-resolution XPS of Bi 4f spectra displays the four evident peaks that appeared at the 156.5, 158.7, 161.9, and 164.1 eV, corresponding to the binding energy of Bi 0 4f 7/2 and 4f 5/2 , Bi 3+ 4f 7/2 , and 4f 5/2 , respectively (Figure 1c). [12]The entire spectra show the similar composition of Zn, and O elements in both bare Zn and Zn@Bi/Bi 2 O 3 electrodes (Figure S2a, Supporting Information), and Zn@Bi/Bi 2 O 3 shows a slight positive shift of binding energy (Figure S2b, Supporting Information), indicating the formation of Zn-Bi chemical bonds.Accordingly, all the above results together certify the successful preparation of metallic Bi layer assisted by the outmost thin Bi 2 O 3 phase containing oxygen groups.
After confirming the successful synthesis of Bi/Bi 2 O 3 , it is of crucial significance to certify the optimal fabrication conditions of Zn@Bi/Bi 2 O 3 electrode.Therefore, a series of selfassembly experiments over bare Zn foil is performed by adopting various immersion durations (1, 2.5, 4 min) and fixed concentrations of reactants (0.04 m).The corresponding composite electrodes covered by the resultant interphase are labeled as Zn@Bi/Bi 2 O 3 −X (X = 1, 2.5, 4).Electrochemical measurements are implemented to study the best electrochemical properties of Zn@Bi/Bi 2 O 3 −X.Electrochemical impedance spectra (EIS) studies illustrate that the lowest resistance of ions diffusion and charge transfer is presented in Zn@Bi/Bi 2 O 3 -2.5 symmetry cell, which can be explained by the raised resistance of ions transport in the thicker interphase (Bi/Bi 2 O 3 -4) and inconsistent distribution of nanosheets for the thinner one (Bi/Bi 2 O 3 -1) (Figure S3, Supporting Information).In addition, the electroactive surface area (A e ) increases the most on Zn@Bi/Bi 2 O 3 −2.5 relative to other modified electrodes and bare Zn (Figure S4, Supporting Information), indicating the evidently increased effective active sites of Zn@Bi/Bi 2 O 3 −2.5.The superior performance of Zn@Bi/Bi 2 O 3 -2.5 is further revealed by long-term cycling experiments in symmetric cells with different electrodes (Zn@Bi/Bi 2 O 3 −X and bare Zn).As expected from the above results, the Zn@Bi/Bi 2 O 3 −2.5 symmetric cell exhibits the longest cycling lifespan for over 2600 h at 1 mA cm −2 (Figure S5, Supporting Information).Complementarily, the morphology and thickness of Bi/Bi 2 O 3 interphase gained after different immersion durations are characterized by scanning electron microscope (SEM).Different from the bare Zn with some minuscule scratches (Figure 1d), the surface of Zn@Bi/Bi 2 O 3 −2.5 is evenly covered by numerous interwoven nanosheets with different sizes of 300-700 nm, that are closely interconnected to form the 3D framework with plentiful microvoids (Figure 1e,f). [13]he corresponding energy dispersive spectroscopy (EDS) mapping reflects the even distribution of Bi and O elements on the Bi/Bi 2 O 3 −2.5 interphase (Figure 1f).This morphology of Zn@Bi/Bi 2 O 3 −2.5 is conducive to homogenizing the electric field distribution and Zn 2+ ions flux while preventing the volume expansion during plating/stripping, superior to the surface morphology of other synthesized Zn@Bi/Bi 2 O 3 −X electrode with the irregular nanosheets stacking (Figure S6a, Supporting Information).In addition, the thickness of the Bi/Bi 2 O 3 -2.5 interphase is 9.6 μm which can be regarded as optimal thickness, because the limited Zn 2+ transport in the thicker interphases (Bi/Bi 2 O 3 -4, 12.5 μm) and the poor suppression ability of the thinner layer (Bi/Bi 2 O 3 -1, 7.8 μm) against dendritic growth (Figure S6b, Supporting Information), [14] which can be supported by the aforementioned EIS and long-term cycling measurement.To sum up, the comprehensive consideration of these explorations discussed above demonstrate that the immersed time of 2.5 min is the optimal synthesis condition for the Bi/Bi 2 O 3 interphase and all the next experiments and characterization are performed with bare Zn and Zn@Bi/Bi 2 O 3 −2.5 (omitted as Zn@Bi/Bi 2 O 3 ).
To comprehend the microscopic structure of optimal Bi/Bi 2 O 3 interphase, their corresponding crystallographic information is characterized via transmission electron microscopy (TEM).Low-magnification TEM images display the two morphologies: stacked nanosheets structure (average size: 300-500 nm) and complete pine-like skeleton consisting of multitude nanosheets (Figures 1g, S7a, Supporting Information).Further, at the selected hexagonal regions of stacked nanosheets, high-resolution transmission electron microscopy (HRTEM) image exhibits that the various grains are hierarchically distributed in the composite phases of Bi/Bi 2 O 3 : most of order-dominated crystalline com-ponents inside the nanosheets, as well as few crystalline with poor crystallinity and disordered amorphous components at the edges of nanosheets, as marked out by the red and purple dividing into four core regions from 1 to 4 (Figure 1h).Specifically, regions 1 and 2 show the four lattice fringes with the spacing of 0.328, 0.227, 0.395, and 0.237 nm, which are respectively indexed to (012), (101), (003), and (104) plane of hexagonal Bi phase (Figures 1h, S8, Supporting Information).In particular attention, in the region 3, three lattice fringes of Bi crystal, corresponding to the (012), (101), and ( 111), comply with a specified spatial arrangement pattern.Correspondingly, the selected-area electrons diffraction (SAED) pattern more intuitively manifests a set of specific crystalline diffraction points related to these crystal planes from region 3, which matches well with the hexagonal close-packed HCP arrangement of crystal Bi phase along the [12-1] zone axis (Figure 1i).Therefore, the results of HRTEM with SEAD are well consistent with the above XRD patterns.In addition, from the region 4, some weakly crystalline and amorphous regions are observed on the edges of nanosheets, which should be corresponded to Bi 2 O 3 phase.Extracted from the nanosheets at the edge-side of pine-like skeletons, SAED pattern shows the noticeable polycrystalline diffraction ring, revealing the coexistence of metallic Bi and oxidized Bi 2 O 3 phase (Figure S7b, Supporting Information).More other HRTEM images also show the amorphous-crystalline interphase for Bi/Bi 2 O 3 (Figure S9, Supporting Information).Then, we further investigate the physicochemical properties of the as-designed Bi/Bi 2 O 3 interphase via utilizing different tests.As revealed by Figures S10-S16 (Supporting Information), this composite interphase possesses the multifunctional natures including low electronic conductivity, large specific surface area and rich mesoporous channels, high ionic conductivity and Zn 2+ transference number, suitable hydrophobicity, and strong adhesion to Zn electrode.Meanwhile, such interphase also enables apparently reducing the chargetransfer resistance of Zn electrode that is smaller than most of literatures (Table S1, Supporting Information).These favorable inherent features lay a solid foundation for the core synergistic regulation mechanism in the following section.

Thermodynamically Favorable Zn Atomic Clusters Dissociation
From our perspective, there is far from enough to effectively inhibit dendrites growth merely depending on the plenty of uniform zincophilic single sites of interphases in previous literatures.In this case, we focus on the dynamic interplay between the Bi/Bi 2 O 3 interphase and Zn atomic clusters and firstly propose such fantastic atomic clusters dissociation mechanism.Then, the ab initio molecular dynamics (AIMD) is utilized to deeply uncover this dynamic atomic clusters dissociation along with time. [15]In this calculation model, the large Zn atomic cluster containing 10 Zn atoms in the form of pyramid arrangement is absorbed on the Zn (001), Bi (001), and Bi 2 O 3 (010) plane (Figure S17,Supporting Information).Based on this model, the calculated radial distribution functions (RDFs) and coordination number analysis of Zn-Zn bonds from the Zn atomic cluster on the three different crystal planes over 3 ps are compared in Figure 2a.The results demonstrate that Zn atomic cluster prefers to interact with Zn (001), due to the stronger primary coordination peak at ≈2.6 Å compared to that of Bi (001) and Bi 2 O 3 (010).Correspondingly, the integrated g(r) curves (marked by the dash line) and -RTln (g(r)) curves (Figure S18a, Supporting Information) exhibit that the Zn atoms of Zn atomic cluster on the Bi (001) and Bi 2 O 3 (010) planes both have a lower average coordination number and smaller dissociation energy barriers (≈0.067 eV), compared to those on the Zn (001) plane (≈0.089 eV).The results suggest that such large tip-type Zn atomic cluster is thermodynamically unstable and more easily decomposed on the surface of Bi (001) and Bi 2 O 3 (010) than on Zn (001), which contributes to avoiding the evolution of large atomic clusters toward the random protrusions during the repetitious electrochemical cycles, especially at rigid conditions.
To further comprehend the effective removal of this Zn atomic cluster manipulated by Bi/Bi 2 O 3 interphase, the RDFs (Figure 2b) and corresponding dissociation energy barriers (Figure S18b, Supporting Information) of various chemical bonds formed at the heterointerface between the Zn atoms from atomic cluster and surface atoms of Zn (001), Bi (001), and Bi 2 O 3 (010) are deeply analyzed.The RDFs curves display that Zn atoms from the atomic cluster will form the typical Zn-Zn bond (≈2.6 Å length) with Zn atom of Zn (001), and the Zn-Bi bond (≈3.0 Å length) with Bi atom of Bi (001).For Bi 2 O 3 (010) plane, the Zn atoms from the cluster can simultaneously bond with Bi and O atoms on Bi 2 O 3 (010), forming a longer Zn-Bi bond (≈3.48 Å) with Bi atom and a shorter Zn-O bond (≈2.05Å) with O atom on Bi 2 O 3 (010).The shorter distance of Zn-Bi bonds than Zn-Zn bonds stands for the weaker interaction between Bi sites of Bi (001), Bi 2 O 3 (010), and Zn atomic cluster.In addition, as shown in Figure S18b (Supporting Information), there exists a higher dissociation energy (0.072 eV) for the robust Zn-Zn metal-bond formed by the chemical interaction between Zn atoms in cluster and the surficial Zn atoms of Zn (001), in comparison with that of the 0.046 eV of Zn-Bi bond between Zn atom of cluster and Bi atom of Bi (001), the 0.048 eV of Zn-Bi bond, and the 0.067 eV of Zn-O bond, respectively formed between the Zn atom of cluster and Bi, O atom of Bi 2 O 3 (010).Also, the visualized videos vividly reveal the greatly unfavorable dissociation process of Zn atomic cluster on the on Zn (001) (Video S1, Supporting Information) than Bi (001) (Video S2, Supporting Information) and Bi 2 O 3 (010) (Video S3, Supporting Information).The above results demonstrate that large Zn atomic clusters are vulnerable to stably agglomerate on the surface of Zn (001), rapidly evolving into unflatted Zn dendrites and further causing batteries to short circuit.On the contrary, the Bi (001) and the Bi atoms of Bi 2 O 3 (010) superior to Zn (001) from the thermodynamic point of view, can boost the spatial movement and further energy favorable elimination of the tip-type Zn atomic clusters on the surface, beneficially achieving the dendrites-free Zn deposition under high current density or areal capacity.Beyond that, the most stable adsorption configuration of Zn atomic cluster absorbed on Zn (001), Bi (001), Bi 2 O 3 (010), and corresponding charge interaction between the atomic cluster and the three different crystal planes are intuitively disclosed in charge density difference (CDD) plots during 3 ps frame (Figure 2c-h).From the CDD patterns, it is seen that Bi (001) shows a much smaller number of electrons transfer with Zn atomic cluster (Figure 2e,f), compared with obvious electrons accumulation/depletion at the Zn (001)cluster interface (Figure 2c,d), indicating the poor charge interaction between Bi (001) and Zn atomic cluster, which further confirms the promising eradication of large atomic clusters induced by Bi phase.
In addition to the above abundant theoretical studies for this innovative dendrites-inhibited mechanism, experimentally, the TEM and HRTEM characterizations are utilized to more intuitively reveal the evolution process of microscopic morphology and grain distribution on Zn@Bi/Bi 2 O 3 electrode after deposition (Figure 2i-n, Figure S19, Supporting Information).Some Zn nanoparticles are uniformly dispersed on the nanosheetlike Bi/Bi 2 O 3 interphase after an initial deposition stage (1 min) shown in Figure 2i.The average sizes of these Zn nanoparticles concentrate around 9.3 nm (Figure 2j).In addition, the corresponding HRTEM image clearly presents the large interseparate grain boundaries and ordered lattice fringes from deposited Zn grains dominated by the (002) plane (Figure 2k).Nevertheless, after 3 min of deposition, an evident transformation is observed for the morphological distribution of Zn nanoparticles from one relatively large, dispersed form to another small dense form (Figure 2l), which is supported by the particle sizes distribution that shows the particle sizes concentrated around 5.2 nm (Figure 2m).Meanwhile, the corresponding HRTEM image confirms that the Zn (002) lattice and grain boundaries with multiple small sizes appear (Figure 2n).This result indicates the formed large tip-type Zn atomic clusters can be dynamically dissociated into small dispersed Zn atomic clusters on the as-designed Bi/Bi 2 O 3 interphase rather than evolving further into larger bumps during the early deposition stage at a high current density, due to the inherent thermodynamic instability of tip-aggregated atomic clusters on interphase.Note that these wide-ranging and evenly arranged small Zn atomic clusters can be regarded as nucleation agents that induce the anchoring of subsequent Zn atoms.As observed in the TEM image from the 6 min of deposition, numerous homogeneous Zn nanoparticles are evenly distributed into the well-hierarchical Bi/Bi 2 O 3 interphase (Figure S19a, Supporting Information), which is further supported by the high-angle annular dark-field scanning TEM images with mapping plots (Figure S20, Supporting Information).Moreover, the HRTEM image manifests the lattice fringes of deposited Zn atoms at most of regions with distributed nanoparticles, and the arrangement of Zn grains is fully covered by the Zn (002) plane (Figure S19b, Supporting Information).Therefore, it can be summarized for the deposition process that numerous Zn atoms are absorbed on the rich zincophilic nucleation sites to form the homogeneous Zn nuclei at the very beginning and then the large atomic clusters are formed as the excess atoms transcend the limits of active sites.At this point, the dissociation effect of the Bi/Bi 2 O 3 interphase can facilitate the decomposition of these Zn atomic clusters and restrict their evolution toward protrusions.As the deposition proceeds, these evenly arranged small Zn atomic clusters tend to laterally expand and grow on underlying interphase, finally evolving into a dendrites-free Zn crystallite layer with the dominance of the Zn (002) plane.

Both Inert Interface Protection and Fast Ions-Deposition Kinetics
HER that competes with Zn deposition, and the accompanying electrochemical self-corrosion with inert byproducts, pose a major threat to the interfacial chemical stability between Zn anode and electrolyte. [16]Therefore, it is essential to investigate the action of Bi/Bi 2 O 3 interphase on inhibiting parasitic reactions.Linear sweep voltammetry (LSV) measurements are performed to appraise the effect of Bi/Bi 2 O 3 interphase on constraining HER.To both avoid the interference from Zn 2+ plating reaction and ensure the electrolyte conductivity during testing, the tests of HER are implemented on Na 2 SO 4 electrolyte.As illustrated in Figure 3a, the HER with Zn@Bi/Bi 2 O 3 electrode occurs at a more negative onset potential (−1.94 V) than that of bare Zn (−1.86 V) at 20 mA cm −2 .Furthermore, the optical images show that the geometric shape of Zn@Bi/Bi 2 O 3 symmetric cell keeps consistent before and after cycling, but the bare Zn cell has evident inflation that contributed to the continuous H 2 evolution (Figure S21, Supporting Information).Further, the H 2 evolution is quantita-tively monitored during the Zn plating/stripping via the in situ electrochemical gas chromatography measurement (Figure S22, Supporting Information).It is observed that, as the continuous process of Zn plating/stripping, the peak intensities of H 2 evolution on bare Zn electrode exhibit an apparent increase and the accumulating amount of H 2 release is over eight times higher than that of Zn@Bi/Bi 2 O 3 counterpart after 6 h.This quantitative result powerfully proves the suppression of H 2 evolution caused by Bi/Bi 2 O 3 interphase, which is consistent with the aforementioned LSV measurement and optical microscopy detection.Moreover, the hydrogen adsorption free energies (ΔG H ) are calculated to deep insight into the pivotal reason for different hydrogen evolution trends of Zn@Bi/Bi 2 O 3 and bare Zn anode.Figure 3b shows that the ΔG H of H absorbed on Bi 2 O 3 (010) and Bi (001) is 1.88 and −0.14 eV, respectively, both much higher than that of −0.54 eV of Zn (001), indicating the thermodynamically unfavorable HER of Zn@Bi/Bi 2 O 3 anode principally manipulated by Bi 2 O 3 component outside the hybrid interphase.Further, the positive effect of Bi 2 O 3 for HER can be verified by the LSV test of Zn@Bi 2 O 3 electrode obtained through the annealing treatment for Zn@Bi/Bi 2 O 3 (Figures S23 and S24, Supporting Information).Note that, Zn@Bi 2 O 3 presents a much lower onset potential (−2.03 V) than bare Zn (1.88 V) at 20 mA cm −2 (Figure S24, Supporting Information), which is consistent with the above ΔG H results.
Equally important, the positive efficacy of Bi/Bi 2 O 3 interphase for suppressing electrochemical corrosion behavior during the rest and cyclic process is studied.Both the Zn@Bi/Bi 2 O 3 and bare Zn foil are dipped into aqueous ZnSO 4 electrolyte.After being soaked for 10 days, the bare Zn foil is tarnished with some white precipitations, yet, there are no visible changes for the surface appearance of Zn@Bi/Bi 2 O 3 foil (Figure S25, Supporting Information).Further, the microscopic surface morphology and composition of the two different electrodes after the immersion test are investigated by using SEM and XRD (Figure S26, Supporting Information).Many irregular hexagonal flakes and tiny particles with various sizes appear on bare Zn foil (Figure S26a, Supporting Information), are recognized as zinc hydroxide sulfate hydrate (Zn 4 (OH) 6 SO 4 •xH 2 O) (Figure S26c, Supporting Information).The formation of these byproducts on bare Zn illustrates the occurrence of severe electrochemical corrosion caused by the irreversible consumption of Zn anode and electrolyte.On the contrary, numerous interconnected 2D nanosheets are evenly distributed on the Zn@Bi/Bi 2 O 3 electrode without founding any flake-like byproducts (Figure S26b,d, Supporting Information), indicating the good chemical stability of Bi/Bi 2 O 3 interphase exposed in the electrolyte.The linear polarization experiments are performed at a three-electrode system to further confirm the outstanding anticorrosion capability of Bi/Bi 2 O 3 interphase under constant impressed current.Zn@Bi/Bi 2 O 3 electrode exhibits a higher corrosion potential and lower corrosion current (−0.947V, 0.699 mA cm −2 ) than that of bare Zn (−0.997V, 5.149 mA cm −2 ) (Figure 3c and Table S2, Supporting Information), indicating the effective suppression of Bi/Bi 2 O 3 interphase on the corrosion trend and velocity, which explains the constrained corrosion reactions aforementioned.Consequently, the Bi/Bi 2 O 3 interphase can restrain the production of insulating side-products, which can decrease the ions transport resistance, thus supporting the fast ions transport at anode--electrolyte interface.The most stable relaxed surface absorbed with Zn atom (left of (g-i)) and their corresponding charge density differences (CDD, right of (g-i), the color regions of cyan and yellow represent the loss and gain of electrons), which respectively corresponds to Zn atoms absorbed on g) Zn (001), h) Bi (001), and i) Bi 2 O 3 (010).j) The corresponding adsorption energy of Zn adsorbed on the three crystal planes.
Subsequently, EIS measurements are executed to examine above speculation.As displayed in Figure S27 (Supporting Information), the impedance of bare Zn symmetric cell shows a sharp increase after being immersed in electrolyte for 10 days, however, the impedance for Zn@Bi/Bi 2 O 3 sample manifests a slight change, which confirms the favorable charge transfer guided by Bi/Bi 2 O 3 interphase.To sum up, the electrochemical selfcorrosion and HER are remarkedly suppressed by virtue of excellent electronic resistivity, inherent high ΔG H, and suitable waterrepelling capability of Bi/Bi 2 O 3 interphase.
Apart from the above-discussed anticorrosion and HER inhibition, fast and uniform Zn 2+ deposition kinetics identically plays a crucial role in the surface morphology and cyclic reversibility of Zn anode.It can be acknowledged that desolvation of hydrated Zn (H 2 O) 6 2+ complex ion in the double electron layers near anode, and Zn adatoms nucleation/growth on anode surface are two critical steps upon the whole kinetic process of Zn deposition. [17]Hence, it is essential to investigate the functionality of Bi/Bi 2 O 3 interphase in regulating the two key kinetics courses.Considering that the main carrier of charge-transfer derives from the desolvation process, hence, the Arrhenius activation energy (E a ) can be approximated as the desolvation energy carrier of hydrated Zn 2+ for Zn@Bi/Bi 2 O 3 and bare Zn. [18] The activation energy of Zn@Bi/Bi 2 O 3 electrode is calculated as 30.59 kJ mol −1 which is much lower than that of the bare Zn counterpart (41.28 kJ mol −1 ), indicating the accelerated desolvation process of Zn@Bi/Bi 2 O 3 during plating (Figure 3d, Figure S28, Supporting Information), which is conducive to reduce interfacial concentration polarization and significantly accelerate ions-transfer kinetics. [19]Next, the chronoamperometry is performed to clarify the ions diffusion/nucleation behavior on two different electrodes by observing the fluctuation state of current versus time.As illustrated in Figure 3e, under an applied overpotential of −200 mV, the current curve of Zn@Bi/Bi 2 O 3 electrode displays a steady and continuous 3D diffusion process at 7.5 mA cm −2 after a temporary 2D diffusion (50 s).This indicates that absorbed Zn 2+ on Zn@Bi/Bi 2 O 3 is locally reduced to Zn 0 on these abundant active sites that are infinitely close to the initial absorption locations with restricted transverse migration, ultimately inducing the even deposition inside the interconnected structure.Conversely, for bare Zn, the current density remains constantly growing beyond 250 s, suggesting a rampant and long 2D nucleation process owing to lateral diffusion of Zn 2+ .At the 2D nucleation behavior, absorbed Zn 2+ accumulates on the most energetically favorable sites for reduction and concentrated nucleation that leads to the "tip effect".Then, the later Zn 2+ tends to accumulate on these primary protrusions to optimize the surface energy as well as exposed regions, eventually burgeoning into large dendrites. [20]Further, the influence of Bi/Bi 2 O 3 interphase on Zn nucleation/growth kinetics can be evaluated by two decisive parameters: nucleation and plateau overpotential. [21]The evident potential drop followed by a moderate potential rise can be discovered on bare Zn and Zn@Bi/Bi 2 O 3 (Figure S29a-c, Supporting Information), demonstrating the occurrence of Zn nucleation behavior on electrode.With respect to Zn@Bi/Bi 2 O 3 , the nucleation overpotential is 30.5, 34.6, and 56.7 mV (Figure 3f) and the plateau overpotential is 19.5, 22.9, and 45.6 mV at the current density of 0.5, 1.0, and 3.0 mA cm −2 (Figure S29d, Supporting Information), respectively, which are both smaller than the case of bare Zn, indicating the accomplishment of lower energy barrier of Zn nucleation and nuclei growth for the Zn@Bi/Bi 2 O 3 (Figure 3f). [22]urther, density functional theory calculations are utilized to deeply reveal the different charge interactions and corresponding adsorption energy of Zn atoms on bare Zn and Bi/Bi 2 O 3 interphase (Figure 3g-j, Figures S30-S32, Supporting Information).In our calculation model, the Zn (001), Bi (001), and Bi 2 O 3 (010) crystal planes are chosen as the typical facet, which is in conformity with the most stable and finally exposed crystal plane of hexagonal Bi phase and monoclinic -Bi 2 O 3 phase established by the aforementioned TEM and XRD results of bare Zn and as-prepared Bi/Bi 2 O 3 .Specifically, Zn atom will be absorbed on the top of the triangle center of three Zn atoms and form the metallic bond with its three coordinated Zn atoms from Zn (001) (Figure 3g).Similarly, Zn atom also prefers to be absorbed in the position that coordinates with three Bi atoms from Bi (001) and presents a more CDD than that of Zn (001) (Figure 3h), which is in favor of capturing and immobilizing plenty of Zn during plating and thus decreasing interfacial concentration gradient and nucleation energy carrier.For the Bi 2 O 3 (010), Zn atom will be simultaneously absorbed by Bi and O and share more electrons with Bi atom from Bi 2 O 3 (010) compared with the O (Figure 3i).Furthermore, based on the most stable absorption models, the calculated Zn absorption energies on different crystal planes are compared in Figure 3j, which shows that the Bi (001) has the strongest absorption energy (−1.01 eV) in comparison to the 0.13 eV of Zn (001) and the 0.74 eV of Bi 2 O 3 (010).This theoretical result further confirms that the Zn 2+ ions after desolvation and charge-transfer will be spontaneously reduced and nucleated on these electrochemical active sites from the inner Bi phase with higher zincophilicity than bare Zn substrate and surficial Bi 2 O 3 phase, which is beneficial to refrain Zn dendrites growth.The exchange current density on electrode under equilibrium state is evaluated to analyze the Zn deposition reaction kinetics.As depicted in Figure S33 (Supporting Information), the Zn@Bi/Bi 2 O 3 anode manifests a higher exchange current density (4.828 mA cm −2 ) than that of bare Zn (2.827 mA cm −2 ), demonstrating the more favorable Zn 2+ reaction rate on Zn@Bi/Bi 2 O 3 under kinetics equilibrium, because of the copious active sites and limited 2D lateral diffusion for Bi/Bi 2 O 3 interphase.

Zn Deposition Behavior Investigation
The positive effect of Bi/Bi 2 O 3 for accelerating ions-deposition kinetics, refraining side reactions, and weakening "tip-effectelicited dendrites", evidenced by Sections 2.2 and 2.3, is expected to directionally guide uniform deposition across the whole 3D network.Consequently, the Zn deposition morphology on Zn@Bi/Bi 2 O 3 and bare Zn electrode in symmetry cells after different electrochemical cycles is straightforwardly investigated by SEM characterizations.As illustrated in Figure 4a, the bare Zn surface is covered by some protruding bulges and loose blocks after the initial 30 cycles, indicating the occurrence of uneven Zn deposition and side reactions.In the following cycles (50 th or 100 th cycle), successive nonuniform plating/stripping processes are occurred on such these huge protrusions and pits, leading to the accumulation of numerous random dendrites with cuttingedges on bare Zn surface.In contrast, a great number of interconnected ultrathin nanosheets are both uniformly distributed on Zn@Bi/Bi 2 O 3 surface with no detection of the evident sheetlike dendrites or lumpy particles after 30 th , 50 th , and 100 th cycle (Figure 4b).This result indicates the uniform Zn deposition in inner abundant zincophilic sites and cavities of such 3D interphase and then even stripping during next discharging, thus causing the preservation of original morphology of Bi/Bi 2 O 3 and inducing the reversible Zn plating/stripping process.Meanwhile, the Zn substrate surface after scaping interphase exhibits a smooth morphology being short of vertical protrusions (Figure S34a, Supporting Information).Furthermore, the corresponding XRD patterns clearly show that stronger diffraction peaks of insoluble byproducts (Zn 4 (OH) 6 SO 4 •xH 2 O, (x = 3,5)) are discovered on bare Zn than that of Zn@Bi/Bi 2 O 3 electrode (Figure 4c).The production of these nonuniform inert byproducts and Zn dendrites will tremendously restrict charge transfer, which can be supported by EIS characterization (Figure S34b, Supporting Information).In addition, such multifunctional Bi/Bi 2 O 3 interphase remains superior stability without other signals of redox peak after 100 cycles (Figure S34c, Supporting Information), further certifying its good chemical stability of postcycling Bi/Bi 2 O 3 , which ensures the continuous effectiveness of the proposed To more directly observe the different deposition morphology at such two electrodes, we fabricate a specifical electrode whose half surface is covered by Bi/Bi 2 O 3 interphase and other half is a bare Zn electrode.The designed electrode is subjected to Zn plating at 3 mA cm −2 , and then the surface morphology of the electrode is observed by SEM and EDS mapping (Figure S36, Supporting Information).After plating 1.5 h, the compact and flat deposits can be discovered on electrode side with Bi/Bi 2 O 3 interphase, indicating the occurrence of byproducts free and uniform deposition inside this 3D framework of Bi/Bi 2 O 3 interphase (Figure S36a,b, Supporting Information).While the electrode side without interphase is occupied by a sea of moss-like particles, random GFs, and vertical nanosheets, demonstrating the production of numerous byproducts (Figure S36a,c, Supporting Information).The deposition process is schematically illustrated in Figure S36d (Supporting Information).More deeply, the deposition behavior on Zn@Bi/Bi 2 O 3 under a high current density of 6 mA cm −2 and different areal capacities (1, 4, 6 mAh cm −2 ) is further studied to gain insight into the deposition mechanism.At an initial plating areal capacity of 1 mAh cm −2 (Figure 4d-1), there is no obvious Zn deposits on the Zn@Bi/Bi 2 O 3 , and note that trace amount of Zn element areas on electrode are mainly distributed along the Bi mapping, as shown in SEM and corresponding EDS mapping (marked by pink dotted line).As deposition capacity increases to 4 mAh cm −2 (Figure 4d-2), the interspaces between nanosheets are gradually filled with deposited Zn with no massive interwoven tenuous nanosheets, which implies that numerous uniform Zn deposits laterally grow and most of them are encapsulated in the whole 3D-interlinked skeleton of Bi/Bi 2 O 3 , probably avoiding the formation of vertical dendrites.When a high plating capacity of 6 mAh cm −2 is operated (Figure 4d-3), the electrode exhibits a dense and smooth surface without visible microvoids, indicating the interspaces are fully filled up with even and flat Zn deposits.Further increasing the capacity to 9 mAh cm −2 , Zn@Bi/Bi 2 O 3 electrodes keep an even Zn deposition layer with only few microscale vertical nanosheets (Figure S37, Supporting Information), demonstrating the dominant dense deposition on the surface of interphases.In addition, the Zn deposition process is monitored by in situ optical microscopy in realtime using homemade symmetry cells at a high current density of 10 mA cm −2 .As shown in Figure S38 (Supporting Information), a small number of protrusions appear on the bare Zn surface after deposition for 15 min, demonstrating the nonuniform surface 2D diffusion and nucleation toward energy-favorable hotspots during starting Zn 2+ deposition.As an unceasing deposition process until 60 min, enormous random moss-like Zn clusters are irregularly overlayed on bare Zn due to the continuous cuttingedge accumulation of deposits and numerous protrusion extensions.By sharp contrast, the uniform deposition layer (marked by blue dash lines) is detected on Zn@Bi/Bi 2 O 3 electrode without detecting volume expansion during the entire electroplating process.Particularly noting, it is essential to intuitively illustrate the positive action of such structure-fine nanosheets array-network on regulating Zn 2+ flux and current density distribution by finite element modeling simulation (Figure 4e and Figure S39, Supporting Information).For bare Zn, uneven intensity gradient and high charge regions emerge on these neighboring Zn protuberances, demonstrating the remarkably inhomogeneous current density and Zn 2+ flux accumulated on surficial protrusion sites of bare Zn, which spark random Zn dendrites growth.In contrast, current density vectors cross through whole nanosheets-array framework and move evenly downward to the bottom side of Bi/Bi 2 O 3 due to its own copious Zn 2+ transport channels , which is favorable to redistribute interfacial Zn 2+ flux and decrease local current density, thus guiding even Zn deposition.

Cyclic Performance Evaluation of the High-Rate and Long-Life Zn Anode
The aqueous Zn||Cu and Zn@Bi/Bi 2 O 3 ||Cu asymmetry cells are assembled to investigate the Zn plating/stripping reversibility on two different anodes through evaluating various key parameters including coulombic efficiency (CE), voltage hysteresis, and cyclic lifespan.At a current density of 4 mA cm −2 and area capacity of 1 mA h cm −2 , Zn@Bi/Bi 2 O 3 ||Cu cell can maintain superior cyclic lifespans of 1000 cycles with high average CE of 99.7%, which is much superior to the bare Zn||Cu cell that starts to undulate fiercely after only operating for 90 cycles (Figure 5a).Enlarging the current density to 5 mA cm −2 , Zn@Bi/Bi 2 O 3 ||Cu still delivers a long cyclic stability with 99.7% average CE (Figure S40a, Supporting Information).The average CE and cyclic life of Zn@Bi/Bi 2 O 3 outperform that of existing protective interphases (Table S3, Supporting Information).In addition, the voltage polarization of Zn||Cu increases sharply at the 200 th cycle (Figure 5b).In sharp contrast, Zn@Bi/Bi 2 O 3 ||Cu cell exhibits a well-leveled charging-discharging platform with moderate voltage hysteresis throughout the whole cycles (Figure 5c).
Identically important, the long-term galvanostatic cycling performance of Zn@Bi/Bi 2 O 3 and bare Zn is further studied in symmetry cells system under various current densities and depths of discharge.As shown in Figure 5d, Zn@Bi/Bi 2 O 3 symmetry cell exhibits an ultralong cycling lifespan of 3120 h (cumulative plating capacity of 1.56 Ah cm −2 ) with a stable voltage oscillation at 1 mA cm −2 and 1 mAh cm −2 (2.6% DOD Zn ), while bare Zn cell delivers a higher voltage hysteresis in the initial cycles and occurs the obvious short-circuit after only 100 h.
Similarly, when increasing current density to 5 mA cm −2 with a 6.4% DOD Zn , the longer cyclic lifetimes (750 h) and smaller average voltage polarization (≈53 mV) still happen on the Zn@Bi/Bi 2 O 3 symmetrical cell, near 30 times higher than the cyclic life of bare Zn cells with evidently large voltage fluctuation (≈300 mV) (Figure 5e).Even at more harsh conditions (20 mA cm −2 , 20 mAh cm −2 ), Zn@Bi/Bi 2 O 3 symmetry cell delivers a prolonged cyclic lifespan of 100 h with proper voltage surge (Figure S40b, Supporting Information).The low voltage hysteresis for Zn@Bi/Bi 2 O 3 than that of bare Zn indicates the constraint of concentration polarization and uneven electric fields distribution especially at high current density.In addition, it is often overlooked in previous literature and need to be particularly noticed that the DOD for Zn plating/stripping is regarded as a more significant parameter to evaluate the battery cycling performance.Because that excess Zn (low DOD) can make up for the disad-vantages caused by side reactions and low Zn utilization, which is hard for meeting practical conditions.However, the electrochemical stability/reversibility of RAZBs is more susceptible to varying interfacial microenvironment in electron double layers or charge concentration distribution in bulk electrolyte only under limited Zn supply (high DOD Zn ).Therefore, the galvanostatic charge/discharge tests are performed for symmetric cells with bare Zn and Zn@Bi/Bi 2 O 3 electrodes under ultrahigh 60% DOD Zn (10 mA cm −2 , 10 mAh cm −2 ).As shown in Figure 5f, Zn@Bi/Bi 2 O 3 symmetrical cell presents an ultralong cumulative plated capacity of 1.5 Ah cm −2 , indicating the high Zn utilization and reversible plating/stripping behavior, which is expected to achieve the commercial application of RAZBs.Impressively, the cyclic performance of symmetric cells with Zn@Bi/Bi 2 O 3 surpasses most of interphases for Zn anode reported before (Figure 5g).Besides, the rate capability of the two symmetry cells is investigated under varied current densities from 1 to 5 mA cm −2 .Apparently, the symmetric cells with Zn@Bi/Bi 2 O 3 electrode always display a much lower voltage hysteresis than the bare Zn cells counterpart under all current densities, and the voltage polarization difference between the two cells is more evident, especially at high current density (Figure 5h).

Full-Cells Performance and Smart Device Demonstration
In order to certify the effect of Zn@Bi/Bi 2 O 3 anode in a practical battery system, Zn-ion full-cells are assembled by using the typical -MnO 2 as cathode coupled with Zn@Bi/Bi 2 O 3 and bare Zn anodes.XRD patterns confirm the successful synthesis of -MnO 2 and SEM images showing the nanorods topology of -MnO 2 (Figure S41, Supporting Information). [23]The cyclic voltammetry test is implemented to illustrate the electrochemical behavior and energy storage kinetics of Zn||MnO 2 and Zn@Bi/Bi 2 O 3 ||MnO 2 full-cells.As displayed in Figure 6a, the CV curves both exhibit two pairs of evident redox peaks, corresponding to the redox reactions between MnO 2 and MnOOH via the cointercalation mechanism of Zn 2+ and H + . [24]This similar CV shape of the two cells demonstrates that the Bi/Bi 2 O 3 interphase has an insignificant influence on the redox reaction of Zn||MnO 2 batteries.Furthermore, Zn@Bi/Bi 2 O 3 ||MnO 2 cell manifests a smaller voltage polarization and higher redox current density than those of Zn||MnO 2 counterpart, suggesting its more superior charge-transfer kinetics and electrochemical reactivity of Zn@Bi/Bi 2 O 3 ||MnO 2 .This is ascribed to the reduced charge transfer resistance of Zn@Bi/Bi 2 O 3 endowed by the Bi/Bi 2 O 3 interphase during plating/stripping, which can be supported by the apparently decreased charge transfer resistance value of Zn@Bi/Bi 2 O 3 ||MnO 2 (Figure 6b).In addition, the rate properties of both full-cells are studied under different current densities (Figure 6c).The Zn@Bi/Bi 2 O 3 ||MnO 2 cell displays an outstanding specific capacity of 272.3 mA h g −1 at a low current density of 0.2 A g −1 .As the progressively increased current density from 0.5 to 2.0 A g −1 , Zn@Bi/Bi 2 O 3 ||MnO 2 still delivers high average specific capacity of 235.3, 152.5, and 118.6 mA h g −1 , respectively.In particular, when the applied current density comes back to 0.2 A g −1 , its specific capacity is basically recovered to the original value, indicating the significantly enhanced Zn plating/stripping reversibility.Meanwhile, the upward trend in full-cell capacity at 0.2 A g −1 can be attributed to two possible reasons: (i) the universal activation process due to the sufficient wetting of electrolyte throughout cathode materials; (ii) the fully activated electrochemical reaction due to the diffusion and migration of Zn 2+ ions inside the cathode material. [25]In sharp contrast, the capacity of Zn||MnO 2 full-cell decays rapidly even at the initial stage and falls down to only 30.1 mA h g −1 at 2 A g −1 .Moreover, from the corresponding charge/discharge curves, it can be observed that Zn@Bi/Bi 2 O 3 ||MnO 2 cell always maintains a much lower voltage hysteresis compared to the Zn||MnO 2 cell at different current densities (Figure S42, Supporting Information).
Apart from the rate capability, the long-term cyclic stability of the two full-cells is further assessed.As displayed in Figure 6d, the charge/discharge curves of Zn@Bi/Bi 2 O 3 ||MnO 2 e) The corresponding scanning electron microscope (SEM) images of bare Zn and Zn@Bi/Bi 2 O 3 anode after 1200 cycles.f) Self-discharging voltage-time curves.g) Long-term cyclic profiles of coin-type full-cells at 1 A g −1 under N/P (6.3) and E/C (45 μL mAh −1 ).h) Long-term cyclic curves of pouch-type full-cells at 1 mA cm −2 .i) Photograph of renewable energy driven battery energy-storage systems.The enlarged Zn@Bi/Bi 2 O 3 battery module as energy-storage device (6 V, 1 Ah), and photovoltaic-solar panel as charging sources and solar-light led as power load tool.
and Zn||MnO 2 cell both present the rising tendency in the initial cycles, which is attributed to the common activation process of battery at the early stages.Note that the Zn@Bi/Bi 2 O 3 ||MnO 2 cell exhibits impressive cyclic stability for 1200 cycles without obvious CE drop and high discharge capacity of 133 mA h g −1 with capacity retention of 89.9% after 1200 cycles, which is better than most reported literatures (Table S4, Supporting Information).However, lacking of Bi/Bi 2 O 3 interphase, the Zn||MnO 2 cell suffers from rapid capacity degradation with a low discharge capacity (38.6 mA h g −1 ) and capacity retention (23.5%).For Zn@Bi/Bi 2 O 3 ||MnO 2 cell, the enhanced cyclic stability and capacity retention are attributed to the inhibited random dendrites growth and violent parasitic reactions on Zn anode favored by Bi/Bi 2 O 3 interphase, which can be verified by the SEM images of Zn@Bi/Bi 2 O 3 and bare Zn after cycling (Figure 6e).It is clearly observed that the 3D-interconnected framework of Bi/Bi 2 O 3 interphase is evenly arranged on the surface of cycled Zn@Bi/Bi 2 O 3 anode without tough flaky byproducts, which is confirmed by the corresponding XRD pattern that preserves the Bi/Bi 2 O 3 peaks (Figure S43a, Supporting Information), implying that the achieved uniform Zn deposition and stable interfacial chemistry in the system of fullcell.In contrast, many randomly aggregated mossy and flaky Zn deposits in different sizes are distributed on cycled bare Zn anode, and these irregular hexagonal flakes are identified as Zn 4 (OH) 6 SO 4 •5H 2 O and Zn 4 (OH) 6 SO 4 •3H 2 O (Figure S43a, Supporting Information).Also, the charge/discharge curves of Zn@Bi/Bi 2 O 3 ||MnO 2 almost keep consistent at the beginning and ending of galvanostatic cycles (Figure S43b, Supporting Information), demonstrating the constantly sustained plating/stripping reversibility of Zn@Bi/Bi 2 O 3 during cycling.Nevertheless, bare Zn||MnO 2 shows an obvious increment of voltage polarization after 1200 cycles than the 5 th cycle initially.Furthermore, the Zn@Bi/Bi 2 O 3 ||MnO 2 cell still deliver a high specific capacity of 265.5 mAh g −1 and 80% capacity retention after 500 cycles at 0.3 A g −1 (Figure S44, Supporting Information).Further, the self-discharge behaviors of the two full-cells are also explored (Figure 6f).During continuous monitoring of open-circuit voltage for 48 h after charging, a brilliant 99.6% of its initial capacity is retained for the Zn@Bi/Bi 2 O 3 ||MnO 2 full-cell, which is much higher than that of 86.7% for the Zn||MnO 2 cell.
In most studies of RAZBs, the excess electrolyte (>100 μL), the small areal capacity of cathode materials (<2 mAh cm −2 ), and the thick Zn foil (>100 μm) were employed to assemble the full-cell for evaluating cycling performance.Although the extended performances were achieved after modifying anodes, they overlooked the key issues of low Zn utilization and surplus electrolyte consumption, which caused the high N/P value and E/C.Therefore, to meet the more practical application of RAZBs, the long-term cyclic performances of the two coin-type full-cells are tested using MnO 2 cathodes under a harsh operation condition (N/P ratio:6.3 and E/C ratio: 45 μL mAh −1 ) and a current density of 1 A g −1 .As shown in Figure 6g, the specific capacity of two full-cells both rapidly increase at 1 A g −1 during the initial 80 cycles, which is credited to the progressive activation process of cathode materials.Subsequently, the Zn||MnO 2 cell manifest a fast attenuation of specific capacity (capacity retention: 12.2%) and pronounced CE fluctuation.Quite the opposite, Zn@Bi/Bi 2 O 3 ||MnO 2 full-cell delivers a fine capacity retention of 86.7% without evident changes of CE, indicating Zn@Bi/Bi 2 O 3 anode still maintains the prominent capability for inducing dendrite-free Zn plating/stripping and restraining interfacial side reactions during full-cells cycling under the practical conditions.
To evaluate the effectiveness of the Zn@Bi/Bi 2 O 3 electrode on small-scale commercial energy-storage applications, a flexible aqueous Zn@Bi/Bi 2 O 3 ||MnO 2 pouch-type cell is fabricated (detail see methods).As displayed in Figure 6h, the Zn@Bi/Bi 2 O 3 ||MnO 2 pouch-type cell maintains a remarkable specific discharge capacity of 149.3 mA h g −1 at the initial cycle and delivers a suitable discharge capacity of 125.5 mA h g −1 with capacity retention as high as 84.1% after 100 cycles at a current density of 1 mA cm −2 .Simultaneously, the value of corresponding CE has also remained close to 100% during 100 cycles.The difference in cycle life between the pouch-type and cointype cells could be attributed to the following two reasons: (i) The discrepancy of testing conditions between pouch-type and coin-type cells.Specifically, the pouch-type cell is tested on a relatively larger current density than coin-type cell, which may cause the more uneven ions transport and electric fields distribution around cathode side, resulting in different cycle life.(ii) The difference in the extent to detrimental issues.Specifically, the pouch-type cell has the higher cathode mass loading and larger electrode surface than coin-type cell.In this case, some inherent side reactions related to MnO 2 cathode may be enlarged for this practical pouch-type cell than coin-type cell during cycling, such as structural collapse, sluggish ions-diffusion kinetics, or the poor electrode-electrolyte contact caused by gas evolution.Moreover, the Zn@Bi/Bi 2 O 3 ||MnO 2 pouch-type cell can still light up smart led-lamps even after, bending, twisting, and folding in the same cell, demonstrating its excellent adjustability, good mechanical strength, and reliable security (Figure S45, Supporting Information).More meaningfully, the potential application of the scaled-up Zn@Bi/Bi 2 O 3 ||MnO 2 battery toward renewable energy storage through cooperation with photovoltaic cell panels is further explored in this work.As shown in Figure 6i, a battery module (6 V and 1 Ah) is made by using four Zn@Bi/Bi 2 O 3 ||MnO 2 batteries in series, which is charged by a photovoltaic-solar panel (30 W and 6 V) during day-time, representing the conversion between solar-energy and electrical energy.Then, the solar-energy driven battery module enables continuously and stably light up the solar-light led (45 W) for 12 h during night-time.Such energyconversion test via integrating the thus-designed battery module with a photovoltaic cell panel presents consistent results in the 15-day continuous experiment, demonstrating its good feasibility and striking potential of Zn@Bi/Bi 2 O 3 ||MnO 2 battery module as a new energy storage device that applies into the future largescale smart grids system.

Conclusion
In summary, a versatile 3D interphase of Bi/Bi 2 O 3 is designed on Zn anode.Apart from inducing the fast ions-desolvation kinetics and targeted nucleation of massive individual Zn adatoms, such interphase derives a synergistic modulation mechanism with clear labor-diversion: thermodynamically favorable Zn atomic clusters dissociation mechanism curbing dendrites formation and chemically inert interface protection mechanism inhibiting parasitic reactions.For the former: there are the weak charge interplay and small dissociation energy, especially between the large Zn atomic clusters and Bi phase.Additionally, these Zn atomic clusters possess low average coordination number and decomposition energy barriers no matter on Bi or on Bi 2 O 3 phase, revealed by AIMD calculation and CDD patterns.Eventually, jointed TEM and SEM results confirm the removal of atoms accumulation and the acquisition of even deposits with high-plating capacity at rigorous testing.For the latter: the electrochemical corrosion and HER can be greatly inhibited on Zn@Bi/Bi 2 O 3 , due to the slight hydrophobicity, high corrosion potential, small onset HER potential, and high ΔG H endowed by Bi/Bi 2 O 3 interphase, thus enhancing the interfacial chemical stability.Given that, Zn@Bi/Bi 2 O 3 ||Cu half-cells maintain 99.7% average CE during 1000 cycles at 4 mA cm −2 .For the practical full-cell configuration, Zn@Bi/Bi 2 O 3 ||MnO 2 pouch-type cells manifest 84.1% capacity retention after 100 cycles at 1 mA cm −2 .Zn@Bi/Bi 2 O 3 ||MnO 2 coin-type cells still deliver 86.7% capacity retention after 500 cycles at 1 A g −1 even at a low N/P (6.3) and E/C (45 μL mAh −1 ).More valuably, a scaled-up battery module with an energy of 6 Wh (6 V, 1 Ah) can uninterruptedly light up the solar-light LED (45 W) for whole night-time (12 h) after being charged by photovoltaicsolar panel at day.Meanwhile, this energy-conversion test can consistently last for 15 days, illustrating its attractive application prospect of this battery-module in future renewable energy source storage systems.

Figure 1 .
Figure 1.Structural characterization of Bi/Bi 2 O 3 interphase.a) X-ray diffraction (XRD) patterns of bare Zn and Zn@Bi/Bi 2 O 3 electrode (inserted diagram: the specific crystal-facets of Bi and Bi 2 O 3 ).b) Raman spectrum of clean Bi/Bi 2 O 3 interphase.c) High-resolution X-ray photoelectron spectroscopy (XPS) spectrum of Bi 4f from Zn@Bi/Bi 2 O 3 electrode.d) Top-view scanning electron microscope (SEM) images of bare Zn. e,f) Top-view SEM images of Bi/Bi 2 O 3 -2.5 interphase (abbreviated as Bi/Bi 2 O 3 ) at different magnification regions and corresponding energy dispersive spectroscopy (EDS) elemental mapping images.g) Transmission electron microscopy (TEM) images of optimal Bi/Bi 2 O 3 interphase.h) High-resolution transmission electron microscopy (HRTEM) images of metallic Bi component (crystalline phase) and oxidized Bi 2 O 3 component (polymorphic and amorphous phase).i) Corresponding selected-area electrons diffraction (SAED) images of the Bi nanograins located at region 3.

Figure 3 .
Figure 3. Enhanced interfacial chemical stability and fast ion-deposition kinetics.a) LSV curves in 1 m Na 2 SO 4 electrolyte.b) The Gibbs free energy of H absorption of Zn (001), Bi (001), and Bi 2 O 3 (010) plane, at the most stable configuration of relaxed surface absorbed with H atom (inserted three diagrams: grey, purple, red, and white spheres represent Zn, Bi, O, and H atoms, respectively).c) Linear polarization curves tested in 2 m ZnSO 4 electrolyte.d) Arrhenius curves and comparison of activation energy at different temperatures.e) Chronoamperometry curves of symmetric cells with bare Zn and Zn@Bi/Bi 2 O 3 electrodes.f) Nucleation overpotential plots based on symmetric cells at the current density of 0.5, 1.0, and 3.0 mA cm −2 , respectively.g-i)The most stable relaxed surface absorbed with Zn atom (left of (g-i)) and their corresponding charge density differences (CDD, right of (g-i), the color regions of cyan and yellow represent the loss and gain of electrons), which respectively corresponds to Zn atoms absorbed on g) Zn (001), h) Bi (001), and i) Bi 2 O 3 (010).j) The corresponding adsorption energy of Zn adsorbed on the three crystal planes.

Figure 4 .
Figure 4. Zn deposition behavior on Zn@Bi/Bi 2 O 3 and bare Zn. a) Top-view scanning electron microscope (SEM) images of a) bare Zn and b) Zn@Bi/Bi 2 O 3 electrode after different plating/stripping cycles using symmetric cells at 1 mA cm −2 , 0.5 mA h cm −2 .Scale bars: 5 μm.c) The corresponding X-ray diffraction (XRD) patterns of bare Zn and Zn@Bi/Bi 2 O 3 after the initial and 100 th cycle at 1 mA cm −2 .d) Top-view SEM images of Zn@ Bi/Bi 2 O 3 electrode after deposition at a current density of 6 mA cm −2 and various Zn-plating capacities (1, 4, 6 mAh cm −2 ).e) The finite-elemental stimulation of current density distribution of Zn@Bi/Bi 2 O 3 and bare Zn electrode.

Figure 6 .
Figure 6.Electrochemical performances of Zn@Bi/Bi 2 O 3 ||MnO 2 and Zn||MnO 2 full-cell and smart device demonstration.a) CV profiles tested from 1 to 1.8 V at a scan rate of 0.1 mV s −1 .b) Electrochemical impedance spectra (EIS) profiles before cycling.c) Rate performances at different current densities.d) Long-term cycling curves of coin-type full-cells at 2 A g −1 .e)The corresponding scanning electron microscope (SEM) images of bare Zn and Zn@Bi/Bi 2 O 3 anode after 1200 cycles.f) Self-discharging voltage-time curves.g) Long-term cyclic profiles of coin-type full-cells at 1 A g −1 under N/P (6.3) and E/C (45 μL mAh −1 ).h) Long-term cyclic curves of pouch-type full-cells at 1 mA cm −2 .i) Photograph of renewable energy driven battery energy-storage systems.The enlarged Zn@Bi/Bi 2 O 3 battery module as energy-storage device (6 V, 1 Ah), and photovoltaic-solar panel as charging sources and solar-light led as power load tool.