A Room‐Temperature Chloride‐Conducting Metal–Organic Crystal [Al(DMSO)6]Cl3 for Potential Solid‐State Chloride‐Shuttle Batteries

The growing demand for substitutes of lithium chemistries in battery leads to a surge in budding novel anion‐based electrochemical energy storage, where the chloride ion batteries (CIBs) take over the role. The application of CIBs is limited by the dissolution and side reaction of chloride‐based electrode materials in a liquid electrolyte. On the flipside, its solid‐state electrolytes are scarcely reported due to the challenge in realizing fast Cl− conductivity. The present study reports [Al(DMSO)6]Cl3, a solid‐state metal–organic material, allows chloride ion transfer. The strong Al‐Cl bonds in AlCl3 are broken down after coordinating of Al3+ by ligand DMSO, and Cl− in the resulting compound is weakly bound to complexions [Al(DMSO)6]3+, which may facilitate Cl− migration. By partial replacement of Cl− with PF6− , the room‐temperature ionic conductivity of as‐prepared electrolyte is increased by one order of magnitude from 2.172 × 10−5 S cm−1 to 2.012 × 10−4 S cm−1. When they are assembled with Ag (anode)/Ag–AgCl (cathode) electrode system, reversible electrochemical redox reactions occur on both sides, demonstrating its potential for solid‐state chloride ion batteries. The strategy by weakening the bonding interaction using organic ligands between Cl− and central metallic ions may provide new ideas for developing solid chloride‐ion conductors.


Introduction
Superionic crystalline materials represent a class of solid materials possessing a high value of liquid-like ionic conductivity.They are used in a variety of electrical devices, such as sensors, [1] electrochromic supercapacitors, [2] thermoelectric, [3] and solid-state batteries. [4,5]Regarding to the solid-state battery system, its solid-state electrolytes (SSEs) have garnered considerable attention due to the main advantages, unlike their liquid counterparts, which do not suffer from electrode corrosion, easy leak and internal shorting, or flammability. [6]Other merits, such as inhibiting dendrite growth, thermal stability during electrochemical cycling and a wide potential window, bring superior safety to energy storage devices. [7]Particularly, the solid electrolytes are well compatible in these battery system cases, such as suppressing the shuttle effect of polysulfide in lithium-sulfur batteries and utilizing low-cost soluble metal halides as the electrode material for batteries. [8,9]As a result, there is substantial demand for solid battery systems.
[12] As a matter of course, its solid-state technologies among various battery systems have scored tremendous achievements (e.g., the Li + conductivity up to ≈1 mS cm −1 ), [13] and big-scale commercial mass production of solid-state LIBs for electric vehicles (EVs) has recently been on the agenda of many manufacturers, including Nissan and Volkswagen. [14]However, because of the limited lithium resources in the earth's crust and the ever-increasing demand for lithium-related energy storage devices, they are becoming economically uncompetitive.As a consequence, there is an urgent need to develop suitable candidates for lithium batteries.In recent years, various systems, based on alkali metal ions (e.g., Na + and K + ), multivalent metal ions (e.g., Mg 2+ , Ca 2+ , Al 3+ , and Zn 2+ ), and anions/polyanions (e.g., F − , Cl − , PF 6 ) as charge carriers, have demonstrated their capability to be viable alternatives to LIBs. [11,15,16]Among these battery systems, chloride ion batteries (CIBs) are appealing due to their high theoretical volumetric energy density (up to 2500 Wh L −1 ) and especially their abundant, low-cost and highly accessible chlorides for both electrode materials and electrolytes, such as MgCl 2 , PbCl 2 , FeCl 3 , BiCl 3 , or CsSnCl 3. [17][18][19][20] The overall electrochemical reactions of electrodes for CIBs are generally as follows: [21] Cathode : where the MCl x and M 0 Cl x represent the metal chlorides.However, metal chlorides dissolution and shuttle in liquid electrolytes is The growing demand for substitutes of lithium chemistries in battery leads to a surge in budding novel anion-based electrochemical energy storage, where the chloride ion batteries (CIBs) take over the role.The application of CIBs is limited by the dissolution and side reaction of chloride-based electrode materials in a liquid electrolyte.On the flipside, its solid-state electrolytes are scarcely reported due to the challenge in realizing fast Cl − conductivity.The present study reports [Al(DMSO) 6 ]Cl 3 , a solid-state metalorganic material, allows chloride ion transfer.The strong Al-Cl bonds in AlCl 3 are broken down after coordinating of Al 3+ by ligand DMSO, and Cl − in the resulting compound is weakly bound to complexions [Al(DMSO) 6 ] 3+ , which may facilitate Cl − migration.By partial replacement of Cl − with PF À 6 , the room-temperature ionic conductivity of as-prepared electrolyte is increased by one order of magnitude from 2.172 × 10 −5 S cm −1 to 2.012 × 10 −4 S cm −1 .When they are assembled with Ag (anode)/Ag-AgCl (cathode) electrode system, reversible electrochemical redox reactions occur on both sides, demonstrating its potential for solid-state chloride ion batteries.The strategy by weakening the bonding interaction using organic ligands between Cl − and central metallic ions may provide new ideas for developing solid chloride-ion conductors.
strangling their application in CIBs.24][25][26][27] Due to the less active charge carriers of Cl − , these oxychlorides on the other side have a reduced energy density compared with their chlorides.Tarascon et al. recently demonstrated the low soluble behavior of transition metal chloride in superconcentrated electrolytes, [9] but it is currently only studied for LIBs.
Considering the great success of solid-state lithium battery technology, introducing solid-state chloride electrolytes (SSCEs) for CIBs has intrigued many researchers.Nevertheless, there are some issues regarding the ionic conductivities of chloride-ion conductors, and few studies have been published.Inorganic crystal electrolytes typically conduct ions across a solid electrolyte by transferring mobile ions through vacancies or interstitial sites, whereas polymer electrolytes conduct ions by continuous coordination between mobile ions and polar groups. [6,28]The inorganic compounds, such as LaOCl, BaCl 2, and PbCl 2, could achieve ionic conductivities of ca. 10 −4 S cm −1 only above 473 K. [29,30] The KCl-doped strategy was reported to improve the ionic conductivity to ca. 10 −4 S cm −1 at 433 K. [29] The perovskite-type CsSnCl 3 and CsPbCl 3 could exhibit this ionic activity at room temperature; however, their phase structure is unstable around room temperature. [30]Furthermore, organic SSCEs, based on the chloride ionic liquids cross-linked polymers, have also been reported to have conductivities ranging from 10 −5 to 10 −4 S cm −1 at room temperature. [15,31]To push the further development of SSCEs, numerous theoretical and experimental investigations must be conducted.
In this work, we reported a novel solid-state chloride-ion conductor [Al(DMSO) 6 ]Cl 3 , prepared by the coordination reaction between AlCl 3 and six DMSO molecules.The prepared compounds exhibit linearly increasing conductivities with temperature and their chloride-ion conductivity at room-temperature is 2.172 × 10 −5 S cm −1 .The coordination of Al 3+ by DMSO reduces the tough ion pair and thus increases the mobility of Cl − , which is thought to be the mechanism of the chlorideion conductive ability of the material compared with AlCl 3 .Furthermore, by partial replacement of Cl − with PF À 6 , the room-temperature ionic conductivity of as-prepared material increases by one order of magnitude up to 2.012 × 10 −4 S cm −1 .The chloride shuttle behaviors of the two asprepared electrolytes have been substantiated by assembling the electrodes in Ag (anode)/Ag-AgCl (cathode) electrode system, and its electrochemical evaluations using the galvanostatic charge-discharge cycling, cyclic voltammetry (CV), and X-ray photoelectron spectroscopy (XPS) analysis.

Results and Discussion
Figure 1a shows the schematic fabrication process of the R-3H phase [Al(DMSO) 6 ]Cl 3 (ADC).The DMSO is known to be able to coordinate metal ions through its O atom.A facile method by mixing AlCl 3 powder with DMSO solvent can result in the formation of coordination compound ADC.Due to the central ion Al 3+ coordinated by six DMSO molecules, the covalent and polar bond between the Al-Cl (2.46 Å) is broken.The Cl ions are stabilized by connecting with the discrete [Al(DMSO) 6 ] 3+ clusters in a longer distance bond (2.75-2.99Å), which may decrease the transfer energy barrier of Cl ions and facilitate its shuttle inside the material.Furthermore, by partial replacement of Cl − with a bigger-size PF À 6 cluster ([Al(DMSO) 6 ]Cl 3- x (PF 6 ) x , ADCTP), the crystalline lattice of ADC could be distorted due to the different ion size units, which may also create disorder or Schottky-type effects to improve the migration capability of Cl − in ADC crystal, as ionic conduction is sluggish in a perfect crystal. [32]The pictures depict that ADC and ADCTP share similar optical morphologies.EDS mapping in Figure 1b,c shows that as-prepared ADC(TP) possess a uniform distribution of C, O, S, Cl, Al, (P), and (F) elements.For sample ADCTP, approximate 7% Cl − are replaced by PF À 6 : Meanwhile, the DMSO is far below-stoichiometric for both ADC and ADCTP, which may contribute to the formation of vacancies inside the crystal and facilitate the transfer of Cl-ion in the mechanism.
Rietveld refinement with XRD data was conducted to obtain more detailed structural variations of [Al(DMSO) 6 ]Cl  starting model for ADC and ADCTP refinement, respectively. [33]Refined crystal parameters are summarized in Table S1, Supporting Information.The good fitting parameters, Rwp = 8.51%, Rp = 6.66% and χ 2 = 1.592 for ADC, and Rwp = 6.70%,Rp = 5.18% and χ 2 = 1.654 for ADCTP, suggest that the derived samples are of high quality.All of the peaks can be successfully indexed to an R-3H phase Al(DMSO) 6  18°for ADC to 91.42°and 127.45°forADCTP, respectively, which could be attributed to the lattice distortions of ADC after adding TBAPF 6 .Furthermore, the lower diffraction intensity of the ( 101) and (10-2) peaks, as well as the amorphous bread peak around 2θ = 12°for ADCTP, indicates that the incorporation of TBAPF 6 increases the disorder degree of the ADC crystal.An appropriate increase in lattice distortion and structural disorder degrees benefits ionic conductivity. [32,34]hermogravimetric analysis (TGA) was performed to determine the thermal stability of asprepared samples, as shown in Figure 3a.The weight loss and heat flow profiles match the reported results well. [35]As seen from the TGA curves, the samples show negligible mass loss before 110 °C, indicating only a trace amount of solvent residue.Zone 1, marked in the graphs, is referred to samples' degradation and the continues liberation of DMSO from crystal in the multistep process.Zone 2 can be explained by the liberation of DMSO and its decomposition product caused by the presence of chloride ions to yield the final product Al 2 O 3 .The crystal ADC starts to lose weight at 121 °C, while ADCTP begins to lose weight at 113 °C.The heat flow peaks shift to a lower temperature degree for sample ADCTP.These results suggest that PF À 6 doping decreases the thermal stability of the Al(DMSO) 6 Cl 3 crystal.TGA analysis of Al(DMSO) 6 Cl 3 and fluorinated organic salt [Al (DMSO) 6 ](BF 4 ) 3 revealed that Al 2 O 3 is the final decomposition product. [35,36]Based on the formation of Al 2 O 3 , the theoretical mass of final products should be 8.5% for ADC and 7.6% for ADCTP.In our case, the final mass ratios for ADC and ADCTP are 6.4% and 5.9%, respectively, which are less than the theoretically calculated value.This could be caused by the presence of extra nonstoichiometric solvent DMSO in the prepared crystals.As shown in Figure 3b, FTIR was used to certify the vibration mode of organic ligands.Table S2, Supporting Information, presents the band position observed in FTIR spectrums of ADC and ADCTP as well as their relative assignments denoted by literature data for [Al(DMSO) 6 ] 3+ salts and TBAPF 6. [35][36][37] These assignments confirmed that ADC and ADCTP possess the expected composition and molecular structure.
The XPS measurements are further conducted to determine the influence of doped PF À 6 chemical valences on ADC.As illustrated in Figure S1a, Supporting Information, the total XPS survey spectrum includes all expected elements for both ADC and ADCTP.Figure 3c,d    ADC has a unique Al 2p peak centered at 71.1 eV and an O 1s peak at 528.7 eV, which can be related to a specific type of ɑ-aluminum oxide, [38] formed during sample processing as a result of reaction between Al 3+ and DMSO into Al 2 O 3 because of extremely exothermic process under the additive of AlCl 3 in DMSO.While this peak is disappeared for ADCTP after adding AlCl 3 into the solution of TBAPF 6 in DMSO, it might be ascribed to a slower exothermic process because the partially pre-solvated DMSO with TBA + in the solution may slow the coordination between Al 3+ and DMSO.The peak at 73.1 eV for ADCTP and 73.4 eV for ADC could be ascribed to the hydrolysis of the sample during transfer for measurements.The Al 2p peaks with high intensity at 75.7 eV for ADC and 75.The temperature-dependent ionic conductivity between 20 and 80 °C was evaluated using the symmetric blocking cell SS¦SE¦SS, as shown in Figure 4a,b.One compressed semicircle at high and moderate frequency range is attributed to the parallel connection of bulk resistance and bulk capacitance, which is represented by the parameters of bulk resistance (R b ) and the constant phase element (CPE).The straight line at the low-frequency region represents the Warburg impedance. [39]The equivalent circuit of the corresponding solid electrolyte of ADC and ADCTP is shown in the inset.Table S3, Supporting Information, tabulates the temperature-dependent ionic conductivities obtained from EIS results.The ionic conductivity values are found to increase when the temperature increases from room temperature to 80 °C.At the higher temperatures, the thermal movement and dissociation of ion pairs would be improved, which increases ionic conductivity.The room temperature ionic conductivities of ADC and ADCTP are 2.172 × 10 −5 S cm −1 and 2.012 × 10 −4 S cm −1 , respectively.This revealed that after the addition of TBAPF 6 , solid electrolyte ADCTP has increased ionic conductivity.Furthermore, the Arrhenius diagrams in Figure 4c were applied to calculate the activation energy Ea.The liner dependence of logσ versus (1/T) follows the Arrhenius law, which indicates phase stability over the given temperature range.Ea values for ADCTP and ADC electrolytes are 0.865 and 2.034 eV, respectively, indicating faster Cl − migration in ADCTP electrolyte.The electrochemical stability was evaluated using LSV measurements at a scan rate of 0.2 mV s −1 from 0 to 3.5 V, as shown in Figure 4d.The decomposition voltage of the ADC system is 2.3 V, which is decreased to 1.9 V after doping 7 wt% PF 6 − .In the cathodic LSV measurements shown in Figure S2, Supporting Information, the ADCTP delivers decreased voltage stability as well.The potential window of a specific material is related to its structure and compositions. [40]By partial replacement of Cl − with PF À 6 , the crystallinity degree and crystal parameters of [Al(DMSO) 6 ]Cl 3 are changed, which might be ascribed to the change of decomposition potential.
The Ag¦SE¦Ag-AgCl cells were assembled for cyclic voltammetry (CV) testing to investigate the chloride ion transfer behavior of asprepared ADC and ADCTP electrolytes, as shown in Figure 5a,b.Regarding to the Ag-AgCl electrode, the EDS result shown in Figure S3, Supporting Information, indicate the ratio of Ag:AgCl is 0.56:1.00.During chlorination and dechlorination procedures, the distinct redox couples of Ag electrodes are around AE0.4 V (vs.Ag/Ag + ) for ADC and around AE0.2 V for ADCTP, respectively.The low polarization of ADCTP system could be associated with its relatively high Cl − ionic conductivity, which contributes to a superior electrochemical activity.Galvanostatic cycling in Figure 5c was implemented to compare the electrochemical cycling stability of ADC and ADCTP during chlorination and dechlorination of Ag-based electrodes.The initial charge/discharge capacities for ADC are 27.1/19.1 mAh g −1 and 64.9/51.1 mAh g −1 for ADCTP, which decrease after 10 cycles to 5.6/6.3mAh g −1 and 31.5/29.8mAh g −1 .It confirms that the ADC crystal can conduct Cl − and its electrochemical performance can be improved by adding the organic salts TBAPF 6 .
Galvanostatic test was performed on Ag-AgCl¦SE¦Ag-AgCl symmetric cells to confirm the stability of the developed solid electrolytes during Cl − plating/stripping behavior toward Ag-AgCl electrode.In comparison with the ADC electrolyte, the ADCTP exhibit relatively steady cycling behavior and a small stable overpotential for Cl − stripping/plating, as shown in Fig- ure 5d.This is assumed to be due to a weak interfacial structure that slows down the kinetics of Cl − stripping and plating in pure ADC crystal.X-ray photoelectron spectroscopy analysis was further applied to verify the chloride ion transfer behavior.After initially electrochemical chlorination toward the Ag electrodes, the battery system of Ag¦SE¦Ag-AgCl was disassembled.Figure S4, Supporting Information, depicts the total XPS survey, which tracked the elements O, C, Ag, and Cl.The Ag 3d peaks in Figure 6a,b display the existence of Ag 0 3d 5/2 and Ag 0 3d 3/2 at 368.5 and 374.5 eV for ADCTP, and 368.2 and 374.2 eV for ADC, respectively, as well as Ag + 3d 5/2 and Ag + 3d 3/2 at 367.8 and 373.8 eV for ADCTP, and 367.6 and 373.6 eV for ADC, respectively.The results confirmed the chloride shuttle capability of these two electrolytes and the successful chlorination of Ag electrodes.The XPS spectrum of Cl 2p signal of Ag electrode are also provided for both before and after chlorination, as shown in Figure S5, Supporting Information.Before conducting an electrochemical reaction, Cl 2p signal is reasonably not able to be detected.After subsequent chlorination, the Cl 2p signals for ADC and ADCTP cantered at ~198.4 and ~200.0 eV correspond to Cl 2p 3/2 and 2p 1/2 of AgCl.

Conclusion and Prospective
In summary, we report a novel metal-organic solid-state chloride-ion conductor [Al(DMSO) 6 ] Cl 3 as the first of its kind.The compound was prepared by a facile mixing AlCl 3 and DMSO at room temperature.The coordination of Al 3+ to DMSO reduces the tough ion pair of Al-Cl, resulting in increased Cl − mobility.Thus, the prepared compound exhibits chloride-ion conducting capability, with a room-temperature chloride-ion conductivity of 2.172 × 10 −- 5 S cm−1 . By partial replacement of Cl − with PF À 6 , the formed [Al(DMSO) 6 ]Cl 3-x (PF 6 ) x compound has more severe lattice distortion and degree of disorder.These defects contributed to enhancing the ionic conductivity of PF À 6 doped sample to 2.012 × 10 −4 S cm −1 at room temperature.Both ADC and ADCTP exhibit linearly increasing conductivities with changing temperatures, and their activation energies are 2.034 and 0.865 eV, respectively.The results of galvanostatic charge-discharge cycling, CV, and XPS for Ag¦SE¦Ag-AgCl cells demonstrate that the [Al(DMSO) 6 ]Cl 3 and [Al(DMSO) 6 ]Cl 3- x (PF 6 ) x electrolytes exhibit novel chloride-ion conductive nature, which can be adopted in allsolid-state Chloride shuttle batteries.In addition, the idea, that introducing organic ligands to weaken the combining energy between cation and anion can realize the shuttle of anion carries inside the solid electrolytes, is instructive for exploring other potential solid electrolytes for anion transfer; in instance, the possibility in solid ionic conductivity of [Cr(DMSO) 6 ] Cl 3 [41] for chloride ions, [Fe(DMSO) 6 ]Br 3 [42] for bromide ions, [La (DMSO) 6 ]I 8 [43] for iodine ions, and some other metal-organic crystals with different ligands.
Synthesis     S7, Supporting Information) was used to load the sample.The acquired XRD data were refined by GSAS software using the Rietveld method. [40]Thermogravimetric analysis (TGA) was used to characterize the thermal properties of the materials using Themys instrument (Setaram, France) with following experimental conditions: (temperature range to 30-600 °C, the heating rate of 10 °C min −1 , and a helium flow rate of 100 mL min −1 ).The functional groups of the materials were confirmed by infrared spectroscopy on a diamond ATR crystal (NICOLET iS50R, Thermo Scientific, USA).X-ray photoelectron spectroscopy (SPECS, Germany) was performed to analyze the surface composition of the samples.Ionic conductivity and electrochemical potential stability: The ionic conductivity at various temperatures was evaluated based on the EIS measurement.The sample powder was tableted into a pellet with a 15.0 mm diameter and a 0.8 mm thickness using the Hydraulic Pelletizer under the pressure of 15.0 MPa and was used as a solid electrolyte (SE).The prepared SE was further assembled in the Swagelok cell with the stainless steels' electrode couples (SS/SS) on both sides, for EIS evaluation using an electrochemical workstation (Gamry Interface 1010 E, Warminster, USA) over a frequency range of 0.1 Hz to 10 6 Hz.The ionic conductivity (σ) of the composite electrolyte was calculated by the following formula: where l, S, and R are the sample thickness, area, and bulk resistance.Temperature dependent conductivity was measured at 20, 35, 50, 65, and 80 °C.
The activation energy (E a ) is obtained from the temperature-dependent ionic conductivity using the Arrhenius equation: where σ 0 is the pre-exponential factor, k is the Boltzmann constant, T is thermodynamic temperature, and E a is the activation energy.Linear sweep voltammetry (LSV) of the sample were recorded with a scan rate of 0.2 mV s −1 using the same SS/SS electrode coupled cells to evaluate the electrochemically stable potential window of as-prepared ADC and ADCTP solid electrolytes within the voltage 0-3.5 V. Electrochemical storage performance measurements: Cyclic voltammetry was conducted with a sweep rate of 0.5 mV s −1 at a potential window from -0.5 to 0.5 V using a prototype cell of Ag¦SE¦Ag-AgCl.Galvanostatic charge-discharge cycling was collected on a Neware battery test system (Neware BTX 7.6, Shenzhen, China) at a current density of 0.1 mA cm −2 with a prototype cell of Ag¦SE¦Ag-AgCl.The Ag-AgCl electrode was prepared by mixing Ag-AgCl composite with carbon black and PVDF in a ratio of 8:1:1 on Ti foil.Regarding the Ag electrode, it was produced by directly painting the nano-silver paste on Ti foil.The Ag/SE/Ag-AgCl cell was assembled in the sequence of Ag electrode, SE and Ag-AgCl electrode using a Swagelok cell.Galvanostatic stripping/plating behavior of the symmetric Ag-AgCl¦SE¦Ag-AgCl cell was explored with a setting current density 0.2 mA cm −2 and an areal capacity 0.2 mA h cm −2 using Autolab PGSTAT204 (Eco Chemie, Utrecht, The Netherlands) workstation.
Figure1ashows the schematic fabrication process of the R-3H phase [Al(DMSO) 6 ]Cl 3 (ADC).The DMSO is known to be able to coordinate metal ions through its O atom.A facile method by mixing AlCl 3 powder with DMSO solvent can result in the formation of coordination compound ADC.Due to the central ion Al 3+ coordinated by six DMSO molecules, the covalent and polar bond between the Al-Cl (2.46 Å) is broken.The Cl ions are stabilized by connecting with the discrete [Al(DMSO) 6 ] 3+ clusters in a longer distance bond (2.75-2.99Å), which may decrease the transfer energy barrier of Cl ions and facilitate its shuttle inside the material.Furthermore, by partial replacement of Cl − with a bigger-size PF À 6 cluster ([Al(DMSO) 6]Cl 3- x (PF 6 ) x , ADCTP), the crystalline lattice of ADC could be distorted due to the different ion size units, which may also create disorder or Schottky-type effects to improve the migration capability of Cl − in ADC crystal, as ionic conduction is sluggish in a perfect crystal.[32]The pictures depict that ADC and ADCTP share similar optical morphologies.EDS mapping in Figure1b,cshows that as-prepared ADC(TP) possess a uniform distribution of C, O, S, Cl, Al, (P), and (F) elements.For sample ADCTP, approximate 7% Cl − are replaced by PF À 6 : Meanwhile, the DMSO is far below-stoichiometric for both ADC and ADCTP, which may contribute to the formation of vacancies inside the crystal and facilitate the transfer of Cl-ion in the mechanism.Rietveld refinement with XRD data was conducted to obtain more detailed structural variations of [Al(DMSO) 6 ]Cl 3 and [Al(DMSO) 6 ]Cl 3- x (PF 6 ) x , as shown in Figure 2. The compound of R-3H phase Al(DMSO) 6 Cl 3 was used as the
Cl 3 .The refined ADC lattice parameter values (a = b = 10.3792Å and c = 22.4656 Å) are close to the sample ADCTP (a = b = 10.3734Å and c = 22.4659 Å).These results indicate that the phase structure of ADC after mixing with TBAPF 6 remains unchanged without the formation of different phases.Meanwhile, the displayed bond angles of O-Al-O and Al-S-O increased from 90.47°and 126.
display high-resolution XPS spectrum of Al 2p and O 1s, respectively.Compared with the electrolyte ADCTP, undoped

Figure 2 .
Figure 2. Refined XRD pattern of a) ADC and the insert of the crystal structure of R-3H Al (DMSO) 6 Cl 3 phase and b) ADCTP, as well as the coordination geometry with Al ions as the central ions (right).

Figure 3 .
Figure 3.Comparison of a) TG curves obtained in helium flow of 100 mL min −1 with heating rate of 10 °C min −1 , b) FTIR spectra for as-prepared ADC and ADCTP in ATR mode, and high-resolution XPS spectra c) Al 2p region, and d) O 1s region.
3 eV for ADCTP belong to Al 3+ coordinated with DMSO.Due to the different environments caused by the different anions, the Al 2p peak of ADCTP delivers a slight shift compared to ADC.The Cl 2p signals for original [Al(DMSO) 6 ]Cl 3 and PF 6 − modified [Al(DMSO) 6 ]Cl 3 are provided as shown in Figure S1b,c, Supporting Information.The addition of PF 6 − anion reduced the binding energy of Cl 2p in the solid electrolyte, which may facilitate the shuttle of chloride inside the material.

Figure 4 .
Figure 4. a) Nyquist plots of SS¦ADC¦SS at the temperatures between 20 and 80 °C, b) Nyquist plots of SS¦ADCTP¦SS at the temperatures between 20 and 80 °C, c) Comparisons of Arrhenius plot for ADC and ADCTP solid electrolytes, d) anodic linear sweep voltammetry (LSV, scan rate of 0.2 mV s −1 ) curves to show the electrochemical stability window of ADC and ADCTP in the 0-3.5 V range.

Figure 5 .
Figure 5. Cyclic voltammetry (CV, scan rate of 0.5 mV s −1 ) curves of a) Ag¦ADC¦Ag-AgCl and b) Ag¦ADCTP¦Ag-AgCl cells at 293 K, c) galvanostatic charge-discharge curves comparison of Ag¦SE¦Ag-AgCl system at a current density of 0.1 mA cm −2 , d) galvanostatic Cl − stripping/plating performance of the prepared Ag-AgCl¦SE¦Ag-AgCl symmetric cell at a current density of 0.2 mA cm −2 and an areal capacity of 0.2 mAh cm −2 .

Figure 6 .
Figure 6.High-resolution Ag 3d XPS spectrum of Ag electrodes after initially electrochemical chlorination in a) ADCTP and b) ADC electrolyte systems.
e12530 produced by exposing the AgCl suspension in water under UV light irradiation over 2 h.Analysis: SEM/EDX results were obtained from Scanning Electron Microscope (SEM, Tescan MAIA 3, Czech Republic).Argon-filled sealable SEM holder (Figure S6, Supporting Information) was used to transfer the samples.Powder X-ray diffraction (XRD) patterns were collected using a Bruker D8 Discoverer powder diffractometer (Bruker) and Cu Kα radiation (U = 40 kV, I = 40 mA).To prevent the sample from degradation, sealable Bruker XRD specimen holder A100B33 (Figure Energy Environ.Mater.2024, 7,