Ultrafast-Charging Silicon-Based Coral-Like Network Anodes for Lithium-Ion Batteries with High Energy and Power Densities

Abstract

Fast charging rate and large energy storage are becoming key elements for the development of next-generation batteries, targeting high-performance electric vehicles. Developing electrodes with high volumetric and gravimetric capacity that could be operated at a high rate is the most challenging part of this process. Using silicon as the anode material, which exhibits the highest theoretical capacity as a lithium-ion battery anode, we report a binder-free electrode that interconnects carbon-sheathed porous silicon nanowires into a coral-like network and shows fast charging performance coupled to high energy and power densities when integrated into a full cell with a high areal capacity loading. The combination of interconnected nanowires, porous structure, and a highly conformal carbon coating in a single system strongly promotes the reaction kinetics of the electrode. This leads to fast-charging capability while maintaining the integrity of the electrode without structural collapse and, thus, stable cycling performance without using binder and conductive additives. Specifically, this anode shows high specific capacities (over 1200 mAh g-1) at an ultrahigh charging rate of 7 C over 500 charge-discharge cycles. When coupled with a commercial LiCoO2 or LiFePO4 cathode in a full cell, it delivers a volumetric energy density of 1621 Wh L-1 with a LiCoO2 cathode and a power density of 7762 W L-1 with a LiFePO4 cathode.