High Areal Capacity and Long Cycle Life Flexible Mild Quasi‐Solid‐State Ag–Zn Battery with Dendrite‐Free Anode

Silver‐zinc (Ag–Zn) batteries are a promising battery system for flexible electronics owing to their high safety, high energy density, and stable output voltage. However, poor cycling performance, low areal capacity, and inferior flexibility limit the practical application of Ag–Zn batteries. Herein, we develop a flexible quasi‐solid‐state Ag–Zn battery system with superior performance by using mild electrolyte and binder‐free electrodes. Copper foam current collector is introduced to impede the growth of Zn dendrite, and the structure of Ag cathode is engineered by electrodeposition and chloridization process to improve the areal capacity. This novel battery demonstrates a remarkable cycle retention of 90% for 200 cycles at 3 mA cm−2. More importantly, this binder‐free battery can afford a high capacity of 3.5 mAh cm−2 at 3 mA cm−2, an outstanding power density of 2.42 mW cm−2, and a maximum energy density of 3.4 mWh cm−2. An energy management circuit is adopted to boost the output voltage of a single battery, which can power electronic ink display and Bluetooth temperature and humidity sensor. The developed battery can even operate under the extreme conditions, such as being bent and sealed in solid ice. This work offers a path for designing electrodes and electrolyte toward high‐performance flexible Ag–Zn batteries.

high surface area can generate uniform electric field distribution and regulate the ion distribution to inhibit the growth of Zn dendrite and improve battery cycling life, but the application in Ag-Zn batteries still needs to be further investigated.Additionally, improved capacity and energy density can be achieved in batteries with binder-free electrodes due to the reduced contact resistance and facile charge transport. [29]As an in-situ growth process, electrodeposition method is of great interest to prepare binder-free electrodes for batteries due to its preparation simplicity, low cost, and low processing temperature. [30]However, rechargeable Ag-Zn battery with both electrodeposited electrodes has not been reported as far as we know.Besides, the use of quasi-solidstate gel electrolytes with high ion conductivity and good flexibility in batteries can not only avoid electrolyte leakage and complicated packaging but also provide a way for the fabrication of advanced flexible batteries. [31]To realize low-temperature operation, organic solvents, such as ethylene glycol and glycerol, can be introduced into the electrolytes as antifreeze agents to improve the freezing resistance. [32]hese technology developments give bright prospects for traditional Ag-Zn batteries, and several flexible rechargeable Ag-Zn batteries have been recently reported.Nevertheless, their overall performances are still unsatisfactory, and breakthrough on high-performance flexible Ag-Zn batteries with high capacity and long cycle life remains a great challenge.
Herein, we report the first flexible mild quasi-solid-state Ag-Zn battery with both in-situ electrochemically grown Zn anode and Ag cathode.ZnCl 2 is employed as the mild electrolyte and glycerol is added to realize antifreeze properties.The effect of anode and cathode structure on the electrochemical performance of Ag-Zn batteries is studied.Copper foam substrate is employed as the 3D current collector to hinder the growth of Zn dendrite and improve the cyclic stability of the battery.Under the same condition, the capacity retention of the battery with copper foam substrate is about 60% higher than that of the battery with carbon cloth substrate after 200 charge-discharge cycles.The cathode structure was modified by electrodeposition and chloridization process to better utilize active materials and enhance the areal capacity of the battery.As a result, the optimized flexible quasi-solid-state battery can afford a high capacity of 3.5 mAh cm À2 at current density of 3 mA cm À2 , a remarkable power density of 2.42 mW cm À2 , and a maximum energy density of 3.4 mWh cm À2 .The developed highperformance flexible battery can be combined with an energy management circuit for practical applications, which can power an electronic ink display and a temperature and humidity sensor, demonstrating its potential applications as power supply in flexible electronics.

Fabrication of Ag-Zn Batteries
The schematic illustration of the fabrication of the flexible quasi-solidstate Ag-Zn battery is revealed in Figure 1.A facile and efficient electrodeposition method is utilized to prepare binder-free anode and cathode.Briefly, the Zn is electrodeposited on electrically conducting substrates, such as copper foam (CF), to serve as the anode (Zn@CF), and the Ag is electrodeposited on the carbon cloth (CC) substrate and further chlorinated to serve as the cathode (AgCl@CC).The PVA-G/ZnCl 2 gel electrolyte is fabricated by mixing PVA, ZnCl 2 , and glycerol.ZnCl 2 is chosen as the mild electrolyte due to better environmental compatibility and battery stability, [16] and glycerol that can interact strongly with PVA chains and inhibit ice crystallization at subzero temperature is introduced for low-temperature operation. [33]Then the Zn@CF anode, AgCl@CC cathode, and PVA-G/ZnCl 2 gel electrolyte were successfully assembled into a classic sandwich device.The excessive water in PVA-G/ZnCl 2 gel electrolyte was removed by aging in fume hood.The aging time is a critical part of battery fabrication process and the capacity of batteries with different aging time are presented in Figure S1a, Supporting Information.Due to more free water and lower battery resistance, the battery with less aging time shows higher discharge voltage and lower charge voltage, which can lead to higher energy efficiency.Moreover, all the batteries with AgCl@CC cathodes have a drop tendency in the first five cycles (Figure S1b, Supporting Information), which may be caused by the different ionic activity in liquid electrolyte and gel electrolyte.Specifically, the AgCl@CC cathodes were pre-chloridized in 0.1 M ZnCl 2 solution before assembled with 2 M ZnCl 2 gel electrolyte, and the lower ionic activity of gel electrolyte may lead to a decrease in battery capacity in the first few cycles.Therefore, all the batteries in this study were aged for 16 h and pretreated for 5 stabilization cycles before further testing.The EIS image of the gel electrolyte is shown in Figure S2, Supporting Information, and the electrolyte has a good ion conductivity of 18.46 mS cm À1 .

Cyclic Stability of Ag-Zn Batteries
Ag-Zn batteries suffer from poor cyclic stability due to the undesired Zn dendrite growth.To inhibit dendrite growth and improve battery stability, 3D Zn anodes with a high surface area are fabricated by electrodeposition on copper foam (CF) and nickel foam (NF).Zn is also electrodeposited on commonly used carbon cloth (CC) as anode for comparison.The X-ray diffraction (XRD) patterns of Zn deposited on these conductive substrates are shown in Figure S3, Supporting Information.The characteristic peaks of metallic Zn (JCPDS-04-0831) [18] are observed in all three samples, indicating the successful growth of Zn metal on all substrates.SEM is utilized to investigate the morphologies of Zn@CF, Zn@CC, and Zn@NF, and all the samples display a nanoflake structure (Figure 2a-f).Zn with a 3D structure is formed on the NF and CF.However, compared with Zn@CF (Figure 2a) and Zn@CC (Figure 2e), Zn@NF displays an uneven distribution of Zn nanoflakes (Figure 2c).Specifically, the Zn nanoflakes tend to grow on the edge of the NF.Although the binding energy of Zn and Ni is lower than that of Cu and C, Ni is an active hydrogen evolution material and the generation of hydrogen is a competing reaction to Zn deposition during the electrodeposition process. [34]As shown in Figure S4a, Supporting Information, the generated hydrogen bubbles can be clearly observed during the Zn electrodeposition, which interferes with the growth of Zn and leads to non-uniform distribution of Zn nanoflakes.
These anodes were further assembled with AgCl@CC cathode and 2 M PVA-G/ZnCl 2 electrolyte into full batteries for long-term test.For the AgCl@CC cathode, the Ag is first electrodeposited on plasma pretreated CC for 1 h before the chloridization process, and the effect of AgCl@CC cathodes on the performance of batteries is investigated and discussed in the following section.As displayed in Figure 2g, the battery with the Zn@NF has a poor initial capacity due to the uneven Zn deposition.Compared with the battery with 3D porous Zn@CF, the battery with Zn@CC has a higher initial capacity, which is attributed to the more adequate infiltration of the quasi-solid-state gel electrolyte into the electrode. [35]However, the battery with Zn@CF anode presents a better cyclic stability, which can remain 2.28 mAh cm À2 (around 90%) after 200 cycles at a high current density of 3 mA cm À2 .In contrast, the batteries with Zn@CC and Zn@NF anodes quickly drop to 1 mAh cm À2 under same condition (around 30% and 50%, respectively).The morphology of Zn anodes after cycling was studied using SEM, as shown in Figure 2h-j and Figure S5, Supporting Information.The Zn nanoflakes on CC and NF turned into microflakes with a size of ~5 lm, while Zn@CF anode can basically maintain its initial nanostructure.The large structure deformation in the batteries with Zn@CC and Zn@NF during cycling can lead to "metal orphaning" and a decrease in surface area, resulting in capacity degradation.Different from the slow capacity decline of the battery with Zn@CC, the battery with Zn@NF has a significant capacity decrease in first 30 cycles, which is ascribed that the uneven distribution of Zn on NF can accelerate structure deformation and capacity failure.The XRD results of the anodes after 200 cycles are displayed in Figure S6, Supporting Information.By-products of ZnO and zinc chloride hydroxide hydrate can be observed in all anodes (Figure S6a-c, Supporting Information), indicating the Zn dendrite formation in all three anodes.However, the Zn@CF shows the weakest dendrite peaks, as shown in Figure S6d, Supporting Information, which is consistent with the SEM results.[38][39] The schematic illustration of Zn morphology on CF and CC after cycling is revealed in Figure 3.The CF substrate can realize better Zn nucleation behavior during charge and discharge process for two reasons.First, due to the lower binding energy between Zn and Cu, [34,36,39] the CF substrate can offer more active Zn nucleation sites than other materials with high binding energy.Second, the larger surface area of 3D CF can also reduce the Zn nucleation hindrance.More importantly, the 3D structure can improve the electrical field distribution, which can avoid the gathering of Zn ion during plating/stripping behavior.Therefore, the better Zn nucleation behavior, as well as more even Zn ion distribution on CF together gives rise to homogeneous Zn deposition and dendrite suppression.However, the Zn on CC tends to gather and grow on limited sites during the charge and discharge process, resulting in unwanted grain growth.Accordingly, the small Zn Energy Environ.Mater.2024, 7, e12493 grains will ultimately transform into Zn dendrite or even dead Zn, leading to the failure of battery.

Areal Capacity of Ag-Zn Batteries
Apart from cyclic stability, high areal capacity is needed for highperformance Ag-Zn batteries.Although binder-free anode and cathode are prepared for Ag-Zn batteries, the areal capacity of the developed batteries is still insufficient for practical applications.To further improve the areal capacity, the structure of electrodeposited Ag is also engineered.As revealed in Figure 4a-c, two different morphologies of silver particles have been achieved by UV and plasma pre-treatments.These pre-treatments can improve the hydrophilicity of the CC substrates (Figure S7, Supporting Information).They also can active the CC surface and reduce the binding energy between C and Ag for the subsequent electrodeposition.Ag micro-polyhedrons with a size of ~50 lm are formed on UV pre-treated CC (Figure 4b), which are significantly different from Ag micro-flakes with a diameter of ~100 lm and a thickness of ~5 lm grown on the plasma pre-treated substrate (Figure 4c).To further gain insights into the growth mechanisms of Ag particles on different substrates, the electrodeposition growth processes at different reaction time are recorded and displayed in Figure S8, Supporting Information.In Figure S8 a1 and b1, Supporting Information, a large amount of Ag particles with a small size are uniformly grown on the UV-treated CC after the 5 min electrodeposition, while several big particles are generated on the plasma-treated CC, implying that more nucleation sites are generated on the UV-treated CC.In this case, with increasing the electrodeposition time, more homogeneous growth of Ag particles can be achieved in the UV-treated substrate, but inhomogeneous nucleation of particles on the plasmatreated substrate leads to irregular growth of particles with a bigger aspect ratio.In addition, since the electrodeposition voltage of cathodes keeps constant in this work, the difference in binding energy caused by the two pretreatments can induce different overpotentials, which is reported as a key parameter in crystal growth. [40]The different overpotentials can promote different growth orientations, leading to different morphologies.Figure 4d shows XRD patterns of the Ag electrodeposited on CC, and the five characteristic peaks are indexed as face-centered cubic (fcc) structure of Ag (JCPDS 04-0783).Ag deposited on UV pre-treated CC reveals a higher ratio of (311) crystal orientation while Ag deposited on plasma pre-treated CC has a stronger ratio of (220) peak, indicating oriented crystal growth of Ag.
The deposited Ag cathodes were further chloridized into AgCl cathodes to improve the battery electrochemical performance.The SEM images of Ag after chloridization process are shown in Figure 4e,f.The particles can basically remain their size, but the surface of the particles becomes coarse.The corresponding energy-dispersive spectrometry (EDS) images of AgCl shown in Figure 4g and Figure S9, Supporting Information, verify the uniform distribution of Ag and Cl elements.The XRD patterns of Ag after chloridization are illustrated in Figure S10, Supporting Information, and the characteristic peaks of AgCl (JCPDS-31-  Energy Environ.Mater.2024, 7, e12493 1238) can be clearly observed. [41]The battery with AgCl cathode presents a capacity of 2.5 mAh cm À2 , while that with Ag cathode only shows 0.9 mAh cm À2 under the same condition (Figure S11, Supporting Information).The higher capacity of the battery with AgCl cathode is caused by different Zn behavior during galvanostatic charge/discharge process and different active cathode material amount.Specifically, in case of the battery with Ag cathode, the first step is the charge process, and the Zn ions tend to move onto the anode, which gives rise to the decrease of electrolyte ion concentration.However, in the battery with AgCl cathode, the first step is the discharge process and Zn anode will react to form Zn ions, which can increase the electrolyte ion concentration and maintain the electrolyte conductivity.Moreover, the chlorination in aqueous ZnCl 2 solution can improve the ratio of AgCl in the cathodes, resulting in higher active material amount and higher capacity.
To further investigate the electrochemical property of different AgCl cathodes, the assembled batteries were tested at current density of 3 mA cm À2 and the GCD curves are shown in Figure 4h.The battery using the cathode, which was pre-treated by plasma and then electrodeposited for 1 h was named plasma-1 h.The same naming rules are applied to the batteries UV-1 h& UV-3 h.The loading mass, considered as a key parameter to battery capacity, [42,43] can be increased with prolonged electrodeposition time (e.g., 3 h).However, the battery plasma-3 h was failed to be prepared due to the too puffy structure of Ag, as shown in Figure S4b, Supporting Information.The charge and discharge voltages of all batteries are 1.1 and 0.8 V, respectively, which are not affected by the different AgCl morphologies.However, the capacity of the battery plasma-1 h (~2.5 mAh cm À2 ) is higher than that of the battery UV-1 h (~2.2 mAh cm À2 ) under similar loading mass.This is because the AgCl micro-flakes in plasma-1 h cathode show a bigger specific surface area than AgCl micro-particles in UV-1 h cathode.The battery UV-3 h with a capacity of 4.3 mAh cm À2 is the largest among all three batteries, because of the larger loading mass of active cathode material (AgCl).

Ag-Zn Battery Performance and Applications
Further electrochemical performance was studied for better understanding of mild AgCl-Zn battery.Firstly, the CV profiles of fabricated battery in Figure 5a display one symmetric pair of redox peaks, corresponding to Ag chlorination and Ag ion reduction behavior.Because UV-3 h battery cannot be fully charged or discharged during the Cyclic Voltammetry test due to too large capacity (Figure S12a,b, Supporting Information), the battery UV-20 min with relatively low capacity was fabricated for CV test and its GCD curve is shown in Figure S12, Supporting Information.In a CV curve, the equation I = av b can reflect the link between the peak response (I) and the scan rate (m).In this equation, a is a constant and b is the coefficient, which indicates the electrochemical kinetics as diffusion or non-diffusion dominated. [16]If the coefficient b is close to 0.5, it represents the battery-type behavior while b reaching 1 means surface capacity-type behavior.In our case, the b values in CV curves are about 0.51, verifying strong battery-type chlorination and reduction behavior.The Figure 5b reveals the GCD curves for battery UV-3 h at current density varying from 1 to 4 mA cm À2 .Similar to CV curves, the two voltage plateaus correspond to the chlorination-reduction reactions and the voltage plateaus in Figure 5b are consistent with the voltage at the same current density in Figure 5a.The capacity of the battery reaches highest level (3.95 mAh cm À2 ) at current density of 1 mA cm À2 and can even remain 2.9 mAh cm À2 when the current density raises to 4 mA cm À2 .At current density of 3 mA cm À2 , the battery UV-3 h represents a capacity of about 3.2 mAh cm À2 , which is close to testing condition of 1C.The long-term performance of UV-3 h is tested under current density of 3 mA cm À2 and the result is displayed in Figure 5c.After five stabilization cycles, the first discharge capacity of battery UV-3 h can reach 4.3 mAh cm À2 at a current density of 3 mA cm À2 and after 130 cycles the discharge capacity remains 3.3 mAh cm À2 , which is 77% of first cycle capacity.The coulombic efficiency in first 130 cycles stays stable at almost 100%, implying the complete reaction during the charge/discharge process.The decrease in capacity and fluctuation in coulombic efficiency after 130 cycles are caused by many factors such as decrease in surface area, loss of gel moisture, as well as the formation of "metal orphaning" by Ag ion migration and Zn dendrite. [18]he long-term performance of battery UV-3 h is not as stable as battery plasma-1 h (shown in Figure 2g, black curve), due to its larger amount of participating active material and higher capacity.Specifically, more time is needed to complete a charge process for battery UV-3 h, leading to more serious dendrite growth and Ag migration. [44,45]The performance (energy and power densities) of our binder-free Ag-Zn rechargeable battery is also compared with other all-solid energy storage devices (Figure 5d).[50] The electrochemical performance of recent reported Ag-Zn batteries and our work are also listed in Table S1, Supporting Information, and our battery displays a remarkable capacity, as well as an outstanding long-term stability in Ag-Zn batteries.To investigate the feasibility of the battery serving as wearable energy supply devices, the charge and discharge test of the UV-3 h battery under bending state is also conducted and the results are shown in Figure 5e.No obvious changes in output voltage or capacity can be observed when the UV-3 h battery is bent from 0°to 135°, suggesting the robustness of the flexible Ag-Zn battery, which remains its electrochemical performance under different angle deformation.
The self-discharge performance of the battery UV-3 h is revealed in Figure 6a and the open circuit voltage (~0.99 V) of the battery barely drops after 20 days.However, the output voltage of a single battery is not suitable for most commercial electronics.Though high output voltage can be realized by connecting multiple batteries in series (Figure 6b), it will increase the battery volume and cause energy loss.In addition, the instantaneous power of the battery is related to the impedance of the external circuit.To power commercial applications, a stable output voltage is required, as well as an appropriate instantaneous power, which are not affected by the load of the external circuit.To achieve this goal, an integrated energy management circuit (AEM10941) is adapted.The input voltage is boosted to a constant 3.3 V by a cascade of two regulated switching converters, and thus the voltage of a single battery can be greatly increased from 0.98 V to 3.27 V (Figure 6c).The performance of our battery under low temperature is also investigated for potential applications.The battery was frozen in a refrigerator to À14 °C firstly and the LED can still be powered by the frozen battery (shown in Figure 6d).In addition, a supercapacitor is applied as buffer to store extra energy when less power is required by the external load.The regulated energy is sufficient to drive a commercial microcontroller (ATmega328p), as well as a 1.54inch electronic ink display (Figure 6e).The schematic of the circuit design is shown in Figure S13, Supporting Information.To demonstrate the viability of our battery for practical applications in electronic devices, especially sensors, we designed a temperature and humidity monitor system including our battery, the energy management circuit and a commercial temperature and humidity sensor.As the schematic illustration of system presented in Figure 6f, the system can measure real-time temperature and humidity and send Bluetooth signal to the computer.A hotplate and wet/dry nitrogen are utilized to build a simulation environment in the laboratory and the temperature and humidity curves for 800 s are shown in Figure 6g.For long time environmental monitoring, four batteries were serially connected as the power source for the monitor system and a 70-h curve is displayed in Figure S14, Supporting Information.

Conclusion
In summary, we designed and fabricated electrodeposited electrodes without any binder for novel mild quasi-solid-state Ag-Zn batteries.Dendrite-free morphology has been realized in the batteries by employing 3D Cu foam as current collector, leading to excellent cycling performance (90% capacity retention for 200 cycles at a current density of 3 mA cm À2 ).High areal capacity was also achieved by engineering the cathode structure through electrodeposition and chloridization process.The developed flexible quasi-solid-state battery can afford a high capacity of 3.5 mAh cm À2 at current density of 3 mA cm À2 , a remarkable power density of 2.42 mW cm À2 , and a maximum energy density of 3.4 mWh cm À2 .This novel battery can also work under the extreme conditions, including being bent and sealed in solid ice.In addition, electronic ink display and Bluetooth temperature and humidity sensor can be powered by a single Ag-Zn battery through integrating an energy management circuit.The excellent cycle performance, high areal capacity, good flexibility and freezing tolerance enable our Ag-Zn batteries to be utilized as reliable power sources for practical energy storage applications under low ambient temperature conditions.
Preparation of AgCl@CC cathodes: The Ag micro-flakes/micro-polyhedron were electrodeposited on carbon cloth (CC) by a source meter (Keithley 2450).Specifically, the work electrode was a 1 cm 9 1 cm piece of CC that was pretreated with plasma/UV for 20 min.A piece of Ag foil (1 cm 9 1 cm) was used as the counter electrode and the electrolyte was 0.1 M AgNO 3 solution.The Ag micro-flakes/micro-polyhedron were then electrodeposited on the CC at a constant voltage of À1 V cm À2 at room temperature under stirring.The electrodes were further chlorinated into AgCl@CC cathode under the current density of 4 mA cm À2 in 0.1 M ZnCl 2 solution with a 1 cm 9 1 cm Zn counter electrode.
Preparation of Zn@CF(CC/NF) anodes: The copper foam (CF) and nickel foam (NF) substrates were purified in 3% HCl solution and washed with deionized (DI) water for several times.The CC substrate was treated with plasma for 20 min before electrodeposition.The Zn nanoflakes were synthesized by a typical electrodeposition method.Specifically, a 1 cm 9 1 cm substrate was used as work electrode and the counter electrode was a 1 cm 9 1 cm Zn foil. 1 g of H 3 BO 3 , 6.25 g of Na 2 SO 4 and 6.25 g of ZnSO 4 •7H 2 O were dissolved in 50 mL of DI water as the electrolyte.The Zn nanoflakes were electrodeposited under a constant current density of 40 mA cm À2 for 1 h at room temperature.
Fabrication and assembly of quasi-solid-state Ag-Zn batteries: The solid gel electrolyte (ZnCl 2 /PVA-G) was prepared as follow: 1.5 g of PVA and 2.7 g of ZnCl 2 were added into 10 mL of DI water, followed by heating at 95 °C and stirring to clear solution.Then 2.4 mL of glycerol was added into the solution, and the solution was heated and stirred for 20 min.The anode and cathode were soaked in the ZnCl 2 /PVA-G solution for 5 min to improve the interface contact.A commercial separator was used to separate the AgCl cathode and Zn anode.After solidification of electrolyte (À14 °C, 1 h), the battery was then aged in the fume hood to remove excessive water.
Materials and device characterization: The morphology of anodes and cathodes were performed on a scanning electron microscopy (SEM, FEI Nova Nano-SEM 450).The X-ray diffraction tests were characterized by an X-ray diffraction (XRD, Empyrean II) with Cu Ka radiation.The cyclic voltammogram (CV) curves were carried out with an electrochemical workstation (Autolab PGSTAT302N) and the galvanostatic charge/discharge (GCD) curves were tested on a battery test system (Neware CT4008-5V10mA-164) with a potential range of 0.6-1.3V.

Figure 1 .
Figure 1.Schematic illustration of the fabrication of the flexible quasi-solid-state Ag-Zn battery.

Figure 2 .
Figure 2. SEM images of electrodeposited Zn on a, b) CF, c, d) NF,and e, f) CC; g) The cycling performances of Ag-Zn batteries with Zn@CF, Zn@CC, and Zn@NF anodes at 3 mA cm À2 ; SEM images of electrodeposited Zn on h) CF, i) NF and j) CC after 200 cycles; Scale bars in SEM images are 50 lm for a, c, e) and 5 lm for b, d, f, h, i, j).

Figure 3 .
Figure 3. Schematic illustration of morphology change for a) Zn@CF and b) Zn@CC during cycling process (ED: electrodeposition).

Figure 4 .
Figure 4. a) Schematic illustration of Ag electrodeposited on UV and plasma-treated carbon cloths.SEM images of Ag electrodeposited on UV b) and plasma-treated carbon cloth c, d) XRD patterns of Ag electrodeposited on carbon cloth with different pre-treatments; SEM images of AgCl on UV e) and plasma-treated carbon cloth f, g) Element mapping images of AgCl on UV-treated carbon cloth.Scale bars in SEM images are 40 lm for b, c, e, f) and 30 lm for g, h) GCD curves of batteries with different cathodes.

Figure 5 .
Figure 5. a) CV curves of battery UV-20 min at different scan rates.b) GCD curves of battery UV-3 h at various current densities.c) The cycle performance of battery UV-3 h at 3 mA cm À2 .d) Ragone plots based on the area of the devices.e) GCD curves of battery UV-3 h bent at different angles at a current density of 3 mA cm À2 .

Figure 6 .
Figure 6.a) Self-discharge performance of the battery UV-3 h (It can be monitored using a battery tester).The inset photograph shows the open circuit voltage of the device.b) Open circuit voltage with different amount batteries in series.The inset shows equivalent circuit.c) The open circuit voltage of the battery UV-3 h without and with the energy management circuit (EMC).d) 1 Photograph of LED powered by frozen Ag-Zn battery with EMC, 2 photograph and 3 Infrared image of frozen Ag-Zn battery.e) Photograph of a 1.54-inch electronic ink display powered by Ag-Zn battery with EMC.f) Schematic illustration of temperature and humidity sensor powered by Ag-Zn battery with EMC.g) Temperature and humidity curve of simulation environment in laboratory.