Constructing High Performance Carbon-based Zinc-ion Hybrid Capacitor Based On Ionic Liquid Electrolyte

Zinc-ion hybrid capacitors（ZIHCs）have attracted attention as an important energy storage device due to safety,green and stability.However,Zn dendrite,corrosion,passivation and irreversible side reactions occur during the charging/discharging process due to the use of traditional aqueous electrolytes,leading to ZIHCs with low energy density,poor rate performance,low coulomb efficiency and short circuits.It severely restricts the commercial application.To solve the above-mentioned problems,this work has reported the novel ionic liquid-based electrolyte.The influence of the ionic liquid-based electrolyte on the stability of metal Zn interface has been systematically investigated,and a carbon-based ZIHCs with the excellent electrochemical performance has been successfully constructed.The results are as follows:1.Zn（BF₄）₂/[EMIM]BF₄ionic liquid-based electrolyte was successfully prepared.The electrolyte exhibits good stability,high conductivity,low viscosity and near-neutral p H value,which can effectively inhibit the formation of Zn dendrites,and achieve effective Zn²⁺plating/stripping（>99%）and long cycling stability（over 1200 h）.The carbon-based ZIHCs constructed with nitrogen-doped porous active carbon as the cathode,Zn foil as the anode and Zn（BF₄）₂/[EMIM]BF₄as electrolyte demonstrates a wide output voltage（1.9 V）,high energy/power density(220 Wh kg^-1/9.5 k W kg^-1)and long cycle life（95%capacity retention after 20000 cycles）.2.Based on Zn（TFSI）₂/Pyr₁₄TFSI electrolyte,the effect of the different additives on ternary electrolyte was systematically studied and Zn（TFSI）₂/Pyr₁₄TFSI/AN electrolyte with excellent properties was optimized.The electrolyte exhibits favorable electrochemical stability and fire-retardant,high conductivity,low viscosity and strong wettability,which realizes effective Zn²⁺plating/stripping behavior.Furthermore,combined with Raman analysisand theoretical calculations,the ratio relationship and interaction of salt-ionic liquid-acetonitrile was systematically investigated,and the optimal electrolyte is screened out.The constructed carbon-based ZIHC a with wide operating voltage of 2.1 V achieved a long-term stable cycle life(the capacity barely decays after 10000 cycles at 5 A g^-1)and high energy density of 84 Wh kg^-1.The developed ionic liquid-based electrolyte in this work establishes the experimental and theoretical basis for the application of ZIHCs.