Construction Of Zinc Ion Hybrid Supercapacitor Based On Carbon Matrix Composites And Its Energy Storge

With the increasing consumption of traditional energy and the demand for the development of green energy,it is imperative to develop hybrid supercapaciors with rapid charge and discharge capacity,high energy density and stable life.Zn²⁺in multivalent metal cations can be quickly inserted/de-embedded on the zinc anode,which has the characteristics of rapid charge transfer,making zinc ion hybrid supercapacitors（ZHSCs）one of the research hotspots at present.Carbon based materials are often used as the capacitive cathode of ion hybrid supercapacitors,but their energy storage performance is poor and can not match the capacitance of the anode,so that the performance of the whole device of zinc ion hybrid supercapacitors can not be further improved.Therefore,it is necessary to design more capacitive cathodes with special structural characteristics and nano structure to obtain zinc ion hybrid supercapacitors with excellent performance.Based on the hierarchical porous structure of biomass based activated carbon,a series of ZHSCs with better electrochemical energy storage properties were constructed in this paper.The specific research contents are as follows:（1）Activated carbon-zinc cobaltate composite electrode materials（HAC-Zn Co₂O₄）were prepared by using layered multi porous activated carbon（HAC）as the skeleton.The layered multi-level pore structure of HAC prevents the accumulation of Zn Co₂O₄ nano sheet and its nano flower structure to a great extent,and promotes the capacitance performance of the assembled zinc ion hybrid supercapacitor device to be greatly improved.Using HAC-Zn Co₂O₄ composite as cathode,zinc foil as anode,2 M Zn SO₄ solution or PVA/Zn（CF₃SO₃）₂gel as electrolyte,aqueous zinc ion hybrid supercapacitor（HAC-y Zn Co₂O₄-ZHSC）and solid zinc ion hybrid supercapacitor（s-HAC-Zn Co₂O₄-ZHSC）were prepared respectively.The results show that HAC-1Zn Co₂O₄ composite electrode material has excellent electrochemical properties,and the specific capacitance is 95.1 F·g^-1 at a current density of 0.2 A·g^-1.The assembled HAC-1Zn Co₂O₄-ZHSC has good electrochemical performance.The maximum specific capacitance is 98.4 F·g^-1(0.2 A·g^-1),and the energy density is 22.6 Wh·kg^-1,and the corresponding power density is 128.6 W·kg^-1.Compared with the capacitance(12.8 F·g^-1)of zinc ion hybrid supercapacitor（Zn Co₂O₄-ZHSC）assembled with pure zinc cobaltate,it is nearly 8 times higher.This provides a new research background for other transition metal oxides to be used in ZHSCs.（2）In order to further improve the capacitance,energy density and power density of ZHSCs devices,HAC-PANI composite electrode materials were synthesized by using highly conductive polymer polyaniline（PANI）.Aqueous（HAC-y PANI-ZHSC）and solid state（s-HAC-PANI-ZHSC）zinc ion hybrid supercapacitors were assembled respectively.It is worth noting that HAC-2PANI composite electrode material has the best electrochemical performance.The specific capacitance value is 415.6 F·g^-1 at the current density of 1 A·g^-1,the capacitance of HAC-2PANI-ZHSC assembled is 245.8 F·g^-1 at the current density of 0.2A·g^-1,and the energy density and power density are 61.7 Wh·kg^-1 and 134.5 W·kg^-1respectively.Compared with the specific capacitance(186.0 F·g^-1)of zinc ion hybrid supercapacitor（HAC-ZHSC）assembled based on activated carbon,the specific capacitance of HAC-2PANI-ZHSC device is increased by 32.2%.The optimum specific capacitance of the assembled s-HAC-PANI-ZHSC is 202.1 F·g^-1(0.2 A·g^-1),and the energy density and power density are 39.5 Wh·kg^-1 and 118.6 W·kg^-1 respectively.Compared with HAC-Zn Co₂O₄ composite electrode material,HAC-PANI as the capacitive cathode material of zinc ion hybrid supercapacitor,its capacitance can better balance with the battery anode material（zinc foil）,which brings better electrochemical performance and higher energy density and power density to ZHSCs devices.