Performance Study And Battery Optimization Strategies For Flexible Aqueous Polyaniline Zinc-ion Battery

With the rapid development of flexible and wearable electronic devices,there is an urgent need to develop flexible energy storage systems that can maintain stable and excellent electrochemical performance in bending,twisting,and even folding states.However,the application of mainstream lithium-ion batteries in flexible electronic devices has shown many limiting factors.In contrast,zinc ion batteries using resource rich Zn2+as charge transport carriers have advantages such as high theoretical capacity,safety,and environmental protection,which have attracted widespread attention from researchers at home and abroad.At present,the mainstream positive electrode materials for zinc ion batteries mainly include manganese based,vanadium based,Prussian blue analogues,and organic materials.Among organic cathode materials,conductive polymer Polyaniline is considered to be one of the most promising materials because of its high conductivity and easy synthesis.However,in practical applications,there are many problems such as low utilization rate of cathode materials,large volume changes during the cycle,resulting in the shedding of active substances,poor contact between electrode electrolytes and zinc dendrite growth,which severely limit its application.To solve the above problems,this paper first explored the best preparation conditions of Polyaniline cathode,obtained the flexible cathode with the highest specific capacity,and assembled the flexible battery for electrochemical testing.On this basis,the positive collector and gel electrolyte were further optimized to solve the problems of poor rate performance and poor bending stability of the battery.The specific content is as follows:(1)Study on the optimal preparation conditions of Polyaniline/carbon cloth composite cathode,the electrochemical performance of PAM gel and the energy storage performance of flexible battery:the influence of pretreatment time on the performance of carbon cloth was carefully explored,and the condition was determined as 3 V constant voltage electrolysis for 4 minutes;The effect of concentrated sulfuric acid concentration on the electrochemical performance of cyclic voltammetry electrodeposited PANI was investigated,and the concentration of sulfuric acid was determined to be 0.5 M.The PANI electrode prepared has a coral bone like structure with high conductivity,suitable deposition amount,and a high specific capacity of 141 mA h g-1;The prepared PAM gel electrolyte has better cycle stability than the glass fiber membrane,and can meet the requirements of the battery.The assembled flexible battery has a specific capacity of 144.7 mA h g-1 at a current density of 0.5 A g-1.After 800 cycles of charging and discharging at a current density of 2 A g-1,the capacity retention rate is about 79%,and the average Coulombic efficiency is about 96.3%.However,due to the limitations of the material system,the battery has problems such as unsatisfactory rate performance and poor bending stability.(2)The construction and characterization of Polyaniline nanofiber network on carbon nanotube modified carbon cloth,the preparation and testing of CNF/PAM dual network gel electrolyte,and the research on the energy storage performance of the flexible battery assembled on this basis:the composite cathode and gel electrolyte were optimized respectively,and the three-dimensional carbon nanotube/carbon cloth collector with high conductivity and high porosity was first constructed.The flexible cathode prepared on this basis has a higher specific surface area,Significant advantages include better interface contact with electrolytes and the ability to reduce interface impedance through π-π bonds.Then CNF was used to modify PAM gel,and a gel electrolyte with double grid structure,which can form hydrogen bonds to significantly increase hydrophilicity,has better mechanical strength,lower interface impedance,and more stable contact with the zinc electrode interface was constructed.The optimized flexible battery has a high specific capacity of 210 mA h g-1 at a current density of 0.5 A g-1,significantly improving rate performance and bending stability.After 800 charges and discharges at a current density of 2 A g-1,the battery’s capacity retention rate is about 83.6%,and the average Coulombic efficiency is 98.7%.The optimization of the battery achieved ideal results.