Study On Three-dimensional Flexible Electrode Material For High Performance Water-based Zinc Ion Battery

As a new electrochemical energy storage device,zinc ion batteries(ZIBs)have received an increasing attention,due to their rapid charge and discharge rates,high power density,environmental friendly property,simple preparation process and long cycling stability.However,its low energy density greatly limits its wide application compared to lithium-ion batteries.In order to improve the capacitance of the water-based zinc ion battery,this paper adopts an optimized current collector structure to enhance the interaction between the current collector and the electrode material.The conductive polymer(polypyrrole and polyaniline)and manganese dioxide are used as the positive electrode material.A flexible water-based zinc ion battery having three-dimensional structural features is prepared.The detail contents are as follows:Firstly,the low ionic conductivity of polypyrrole limits its rate performance in ZIB.In order to solve the above problem,in this chapter,a conductive aerogel composed of polyvinyl alcohol(PVA)and graphene is successfully prepared as a current collector to improve the polypyrrole-based flexible water-based zinc ion battery.The aerogel current collector has three-dimensional structural characteristics,a large specific surface area,good electrical conductivity and super flexibility.The electrochemical performance of the prepared water-based zinc ion batteries based on Ppy cathode materials was investigated.By optimization the ratio of PVA and graphene,the obtained batteries own good electrical capacity and excellent rate performance,with a capacitance of 151.1 mAh/g at a current density of 0.5 A/g,and still possess a high specific capacity of 87.6 mAh/g even at a high current density of 16 A/g.Secondly,in order to improve the conductivity of manganese dioxide,carbon cloth with excellent electrical conductivity was applied as a current collector.The metal nickel directly was grown on carbon cloth by electrochemical deposition and aerobic combustion method to produce a three-dimensional conductive porous structure,then manganese dioxide active material was grown by in situ synthesis on the prepared carbon cloth.At last,the zinc ion battery based on the manganese dioxide/nickel/ carbon cloth preforms an outstanding energy density,and the energy density can reach 356 m Wh/g at a power density of 1.2 W/g.Thirdly,to solve the poor cycle stability of polyaniline(PANI)and the poor hydrophilicity of carbon cloth collector in zinc ion battery,the electrolytic method was utilized to modify the carbon cloth as current collector and then polyaniline was deposited by electrochemically deposition.The modified carbon cloth/ PANI possess threedimensional structure.The obtained flexible water-based zinc ion battery based on the above electrode and current collector displays excellent power densities(16.6 W/g@223.5 mWh/g)and energy densities(464.1 mWh/g@0.56 W/g).Attributing to the electrolysis,the corresponding ZIB shows a good capacity rate and delivers an electrochemical cycling stability with 93.2% retention after 1500 cycles the current density of 4 A/g.