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

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, high-performance LICs using both battery and capacitor type Mn2V2O7-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 at 15 kW kg(-1). More importantly, the MVO-G//HSAC LICs also show excellent cycling stability of 90% after 15,000 cycles, which is expected for high performance energy storage systems. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.