Improving electrochemical performances of lithium-ion capacitors employing 3D structured Si anodes

Abstract

Lithium-ion capacitors (LICs) are gaining attention from researchers as the demand for an energy storage device that addresses the drawbacks of lithium-ion batteries and supercapacitors is increasing. Silicon (Si) is a desirable anode material for LICs due to its high theoretical capacity and low working potential. However, Si experiences extreme volume changes of up to 300%, which cause a poor cycle life. To mitigate mechanical stress in Si anodes, we fabricated a three-dimensional structured Si electrode using a pore-forming agent and evaluated its physical-electrochemical properties. The pore network of the structured Si electrode effectively buffered the volume change, alleviating crack formation in the electrode and resulting in improved cycle stability. The LIC full cell using the structured Si had a high energy density of 191.4 Wh kg−1 at a power density of 723.7 W kg−1. Our approach is compatible with conventional electrode fabrication systems and provides a cost-effective and practical method for pure Si anodes suitable for use in LICs through a simple pore-structuring process.