Intercalation-pseudocapacitance hybrid anode for high rate and energy lithium-ion capacitors

摘要

Existing rechargeable batteries not only fail to meet the demand for high power applications but also cause heavy metal pollution.Li-ion capacitors(LICs),which can achieve higher charging speeds and energy densities than supercapacitors,have attracted extensive attention.Nevertheless,sluggish Li-ion diffusion of the battery-type anode results in limited rate performance of LICs.Herein,highperformance LICs using both battery and capacitor type Mn_(2)V_(2)O_(7)-graphene(MVO-G)anodes and hempstem-derivated activated carbon(HSAC)cathodes with a large surface area are first reported.In addition to high pseudocapacitance,the MVO-G possesses the advantage of fast Li^(+)storage performance making it a suitable choice for advanced LIC anodes.Graphene is employed to enhance overall conductivity and cycling stability leading to enhanced energy storage.The MVO-G//HSAC LICs exhibit a high energy density of 148.1 Wh kg^(-1) at a power density of 150 W kg^(-1) and 25 Wh kg^(-1) even at15 k W kg^(-1).More importantly,the MVO-G//HSAC LICs also show excellent cycling stability of 90%after15,000 cycles,which is expected for high performance energy storage systems.