Design And Performance Research On Polyaniline Nanoarray Cathode For Zinc Ion Hybrid Capacitor

Zinc ion hybrid capacitors（ZHCs）have great potential for development and application due to their advantages of low cost,high safety,high energy density,high power density,and excellent cycling stability.However,the development of ZHCs is all still in the initial stage and have many shortcomings.In particular,the limited ion adsorption capacity of the cathode material leads to insufficient charge storage capacity,and the active material of the cathode material is easily shed leading to rapid electrochemical performance degradation.In view of this,this thesis addresses the effects of the composition,microstructure,and electron transfer of ZHCs cathode materials on their energy storage properties,and successfully constructs flexible electrode materials with high electrochemical and mechanical properties.The main studies are as follows.（1）Using carbon cloth（CC）as the substrate and urea,boric acid and polyethylene glycol as the precursors,the high specific capacity polyaniline（PANI）was closely combined with three-dimensional boron-carbon nitrogen（BCN）nanoarrays through strategies such as high-temperature calcination and electrochemical deposition,i.e.,the development of both bilayer capacitance and pseudocapacitance electrode materials was achieved,and CC@BCN@PANI flexible anode materials with core-shell three-dimensional nanoarray structure were prepared.Benefited from the high electrical conductivity and stable chemical structure of BCN nanoarrays,the excellent ion storage capacity of PANI,and the good synergy between them can prevent PANI shedding and alleviate the expansion/contraction phenomenon during charging/discharging,while releasing the stress generated during electrode bending.In essence,it promotes the kinetic process and improves the electrochemical performance of the material.The electrochemical performance tests show that CC@BCN@PANI has high specific capacity（145 m Ah/g at a current density of 0.5 A/g）,high energy density（116.78 Wh/kg）,high power density（12 k W/kg）,and excellent cycling stability（86.2%capacity retention after 8000 cycles）.Thus,this study can provide an effective strategy for the development of high-performance ZHCs cathode structures.（2）The ZHCs were assembled with CC@BCN@PANI cathode and the influence of different Zn SO₄ electrolyte concentrations on its electrochemical performance was investigated.The gelatin/Zn SO₄ electrolyte with the most suitable concentration for the CC@BCN@PANI electrode was configured to assemble"sandwich"and fiber-type zinc ion hybrid capacitor（FZHCs）to test the electrochemical properties and mechanical stability.Due to the stable three-dimensional core-shell structure and the high specific capacity of PANI,the"sandwich"FZHCs exhibited a high specific capacity of 160 m Ah/g at a current density of 0.1 A/g,and after 450 cycles at 2 A/g,the capacity retention was 87.7%,even after bending at angles of 180°and 90°（the capacity retention rate reaches86.2%after 200 bends）,the FZHCs still maintained excellent specific capacitance.Moreover,the assembled fiber-type FZHCs also had high specific capacitance（291 m F/cm² at a current density of0.5 m A/cm²）,a high energy density of 90.94μWh/cm².Thus,the flexible CC@BCN@PANI composite electrode prepared in our research also can provide a new approach for the development of flexible energy storage devices.