Preparation And Electrochemical Properties Of Positive Electrode For Zincsilver/Air Hybrid Battery

With the rapid development of wearable electronic devices,flexible secondary batteries with large capacity have become a hot spot.Among them,silver zinc oxide（Zn-Ag₂O）battery with stable output voltage,high energy density,safety,together with no environmental pollution,is one of the candidate.However,its application is limited by poor cycle performance and low energy density caused by the low utilization of active materials.To solve these problems,a new binderless positive electrode preparation method based on flexible carbon cloth（CC）has been developed.Co-MOF with triangular nanosheet structure was prepared on the surface of carbon cloth by a simple liquid phase reaction with 2-methyl imidazole（C₄H₆N₂）and cobalt nitrate hexahydrate（Co（NO₃）₂·6H₂O）.After carbonization,N-doped carbon nanosheet array（NC）was obtained.After electrodeposition of silver and electrochemical oxidation of Ag₂O,it was used as the positive electrode.This method avoids the use of binder and increases the load area of Ag₂O,thus improving the electrochemical performance of zinc silver battery.The Zn-Ag/Air hybrid battery is combined with the zinc Air battery,which can provide higher energy density and cycle life by combining the performance advantages of the two kinds of batteries.The button zinc-silver battery with CC-Co₃O₄-Ag positive electrode assembled in carbonized air atmosphere has an initial discharging capacity of 0.0905 m Ah/cm² at a current density of 0.2 m A/cm².However,the first discharging capacity of CC-NC-Co₃O₄-Ag positive electrode carbonized in argon atmosphere is 0.5888 m Ah/cm².This is because the protection of NC nanosheets in argon atmosphere improves the battery capacity.The CC-NC-Co₃O₄-Ag positive is assembled into a water-based zinc-silver battery.When the current density was 5 m A/cm²,the first discharging capacity reaches 0.96m Ah/cm².The capacity retention rate is 92%,with the coulomb efficiency maintains at about 98%even after 100 cycles.The flexible zinc-silver battery is assembled with gel electrolyte as electrolyte and membrane.At 1.0 m A/cm² and 1.8-1.0 V,the discharging capacity of the flexible zinc-silver battery reaches 0.55 m Ah/cm²,and the capacity is 0.42m Ah/cm² after 10 cycles.Capacity retention is 76%and coulomb efficiency is close to100%.The flexible zinc-silver/zinc-air hybrid battery was assembled.At 1.0 m A/cm² and1.8-1.0 V,the two discharging platforms of 1.45 V and 1.05 V appeares.The flexible hybrid battery finally obtained a high capacity of 2.73 m Ah/cm².It delight the LED.These proves that CC-NC-Co₃O₄-Ag electrode can be used as the positive electrode of Zn-Ag/Zn-Air hybrid battery,which obtain not only the high voltage of Zn-Ag battery,but also the large-capacity characteristics of Zn-Air battery.This method provides a new strategy for the development of flexible batteries in the future.