Carbon-Encapsulated Silicon@Co_0.85Se Anode for High-Performance Lithium-Ion Batteries

Silicon (Si) anodes exhibit remarkable theoretical capacity, enabling them to be attractive candidates for high-energy-density lithium-ion batteries. However, conventional surface-modification strategies on Si often fail due to insufficient adhesion between the coating and Si, thereby giving rise to interfacial degradation and poor ion/electron transport. Here, we develop a heterointerface-engineered Si@Co_0.85Se/N-doped carbon (NC) anode. Porous Si is coated by metal-organic framework (MOF)-derived Co_0.85Se, and Si@Co_0.85Se is encapsulated in an NC matrix. This design establishes robust Co-Se-Si bonding at the heterointerface, enabling highly efficient ionic and electronic transport. The Si@Co_0.85Se/NC anode delivers a large specific capacity of 1155.1 mA h g^-1 after 100 cycles at 0.2 A g^-1 and remains stable over 600 cycles at 1.0 A g^-1. As a pairing with a LiFePO₄ cathode, the full cell demonstrates exceptional cycling stability. In situ X-ray diffraction and in situ Raman spectroscopy confirm highly reversible electrochemical processes. These findings provide a heterointerface-designing strategy for Si-based anodes to achieve synergistic enhancement for high-performance energy storage.