Nano hollow carbon sphere buffering design to address volume expansion in micro-silicon anodes of lithium-ion batteries

Abstract

Silicon-based materials are known as promising anodes for a new generation of lithium-ion batteries due to their high theoretical capacity and various properties, but the huge volume expansion of silicon-based electrodes greatly limits its development. Herein, this study designs an integrated co-carbonized layer (CCL) silicon-based anode with nano hollow carbon sphere (HCSs) buffer materials (HCSs/Si/G-CCL) to regulate the volume expansion of electrode and effectively increase the content of active materials. As a result, the HCSs/Si/G-CCL electrode with buffer materials performs a good buffer effect, and the electrode expansion degree is only 4.0% after cycles, far lower than the commercial anodes 174.3%, which effectively relieves the huge volume expansion of silicon formed in lithium. Compared with control electrodes, HCSs/Si/G-CCL exhibits a reversible capacity of 702 mAh g−1 after 100 cycles at 1.0 A g−1 with a capacity remained near of 75%. The full cell also manifests excellent cycle stability that remains commercial-level areal capacities of 1.9 mAh cm−2 after 100 cycles. This work provides a universal solution to solve the volume expansion of silicon-based anode materials by electrode design for the prospect of large-scale application of micro-silicon anodes in lithium-ion batteries.