High-power lithium-ion hybrid supercapacitor enabled by holey carbon nanolayers with targeted porosity

Abstract

Lithium-ion hybrid supercapacitor emerges as a promising candidate to bridge the performance gap between lithium ion batteries and supercapacitors. However, for current lithium-ion hybrid supercapacitor systems, high energy storage is usually accompanied with the sacrifice of high power density due to the mismatched kinetics between the sluggish lithium intercalation in anode and the rapid ion adsorption/desorption at cathode. In this work, we design a simple and controllable synthesis of holey carbon nanolayers with targeted porosity as both anode and cathode to achieve rapid electrochemical kinetics in lithium-ion hybrid supercapacitors. The mesoporous structure, enlarged interlayer spacing and excellent electrical conductivity of anode ensure greatly mitigated lithium diffusion. Simultaneously, the hierarchical porous texture and large external active surface area of cathode contribute to an outstanding capacity of 140 mAh g−1 and better rate capability. The lithium-ion hybrid supercapacitor based on holey carbon nanolayers shows a high energy density up to 181 Wh kg−1, and still preserves a remarkable energy density of 114 Wh kg−1 even at an ultra-high power density of 65 kW kg−1. This work illustrates the pertinence of porosity and morphology manipulation as a competitive strategy for rational fabrication of lithium-ion hybrid supercapacitor electrodes with high power density.