Affiliation:
1. School of Advanced Materials Peking University Shenzhen Graduate School Peking University Shenzhen 518055 China
2. School of Energy and Power Engineering Jiangsu University Zhenjiang 212013 China
3. Institute of Materials Research Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen 518055 China
4. National Key Laboratory of Materials for Integrated Circuits Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China
Abstract
AbstractRecently, the rock‐salt (RS) phases are utilized to enhance the surface stability of LiCoO2 (LCO), however, the optimization mechanism still remains vague. Herein, the structure stability of LCO is successfully enhanced via constructing a tough surface RS layer (≈5 nm), namely, the RS‐LCO. This surface RS layer plays a significant role on capturing the migrated lattice O ions upon charging, leading to the progressive phase transition from an inert RS phase to an ionic conductive spinel phase in the surface, and suppresses the bulk H1‐3 separation beyond 4.6 V. As a result, not only the oxygen redox induced side reactions are greatly reduced, but also the Li+‐ion's transport is significantly promoted. The RS‐LCO/Li cells show a remarkable cycle stability with 89.7% capacity retention after 1000 cycles in 3–4.6 V at current of 1 C (1 C = 200 mA g−1), and 81.2% capacity retention after 400 cycles in 3–4.65 V at 1 C. Besides, the RS‐LCO/graphite cells show nearly no capacity decay in 600 cycles in 3–4.55 V at 1 C. This work provides a new insight to understand the role of surface RS phase layer on developing the advanced LCO.
Funder
National Natural Science Foundation of China
Basic and Applied Basic Research Foundation of Guangdong Province
Subject
General Materials Science,Renewable Energy, Sustainability and the Environment