Reversible Silicon Anodes with Long Cycles by Multifunctional Volumetric Buffer Layers.

Establishing a stable, stress-relieving configuration is imperative to achieve a reversible silicon anode for high energy density lithium-ion batteries. Herein, we propose a silicon composite anode (denoted as T-Si@C), which integrates free space and mixed carbon shells doped with rigid TiO2/Ti5Si3 nanoparticles. In this configuration, the free space accommodates the silicon volume fluctuation during battery operation. The carbon shells with embedded TiO2/Ti5Si3 nanoparticles maintain the structural stability of the anode while accelerating the lithium-ion diffusion kinetics and mitigating interfacial side reactions. Based on these advantages, T-Si@C anodes demonstrate an outstanding lithium storage performance with impressive long-term cycling reversibility and good rate capability. Additionally, T-Si@C//LiFePO4 full cells show superior electrochemical reversibility. This work highlights the importance of rational structural manipulation of silicon anodes and affords fresh insights into achieving advanced silicon anodes with long life.