Study Of Capacity Decay Mechanism Of Zinc-silver Battery For Wet-charge Storage

The zinc-silver battery has the characteristics of long-term storage.When using it,it is necessary to predict the capacity and other performance indicators that the battery can provide after storage,so as to judge whether the battery meets the use requirements.In the current research,the method for predicting the performance index of zinc-silver batteries after storage is mainly to store the batteries in dry state under natural conditions for several years to more than ten years,and then obtain the discharge capacity value of the battery after long-term storage.This method is not only time-consuming but also high costly,and these problems can be solved by accelerated life testing.In order to study the reasonable temperature of the zinc-silver battery in the accelerated life test of wet charging storage,the capacity type zinc-silver battery（XY-2RS）and the power type zinc-silver battery（XY-2GS）were studied by combining the external characteristic analysis method and the disassembly analysis method to obtain discharge performance and capacity decay mechanism after storage at 40℃～70℃.The details are as follows:（1）The discharge capacity of the XY-2RS battery before storage is 3.60Ah,and the discharge capacity after high temperature storage is lost.The capacity loss at 65℃is the largest,and the discharge capacity is only 2.67Ah.Through the physical diagram of battery and electrode,it shows that the internal pressure of battery increases,and the zinc electrode deforms.Meanwhile,XRD,SEM,and EDS of the electrode show that the decomposition rate of silver peroxide in the positive electrode increases with temperature,the amount of zinc oxide in the negative electrode gradually increases,and the morphology of the active material changes.Also,the EIS of the battery and positive electrode indicates that colloidal silver migration occurs at 65℃.（2）The discharge capacity of the XY-2GS battery before storage is 4.20Ah,the discharge capacity loss after storage at 55℃is the largest,and the discharge capacity is only 2.03Ah;the physical diagram of the battery and the electrode shows that the internal pressure of the battery increases and the positive and negative electrodes are70℃,and the material on the electrode surface changed after storage.XRD,SEM and EDS of the electrode show that the decomposition rate of the positive electrode active material accelerated with increasing temperature,and the content of zinc element gradually increased,up to 6.6%at 70℃.（3）Analysis of the decay mechanism of the wet charge storage capacity of Zn-Ag batteries shows that the main reasons for the decay of the capacity of XY-2RS batteries after the wet charge storage at 40°C to 70°C are the decomposition of silver electrode,the deformation of zinc electrode and the migration of colloidal silver.The main reason for capacity degradation of the XY-2GS battery is Ag O/Ag₂O charge transfer resistance increases,zinc electrode autolysis and active material effective area decrease.The final determination of the temperature stress of the XY-2RS and XY-2GS batteries used in the accelerated temperature storage life test is 50℃and 40℃are the most reasonable.