Building Homogenous Li2TiO3 Coating Layer on Primary Particles to Stabilize Li‐Rich Mn‐Based Cathode Materials

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2022-03, Vol.18 (10), p.n/a
• Main Authors: Liu, Jiuding, Wu, Zhonghan, Yu, Meng, Hu, Honglu, Zhang, Yudong, Zhang, Kai, Du, Zexue, Cheng, Fangyi, Chen, Jun
• Format: Article
• Language: English
• Subjects: Anode effect; Anodic dissolution; Cathodes; Cathodic dissolution; Coated electrodes; coating; Dissolution; Electrode materials; Interface reactions; Ions; Lithium; Lithium-ion batteries; Li‐rich materials; Mass spectrometry; molten salt; Molten salts; Nanotechnology; Phase transitions; Photoelectrons; primary particles; Titanium dioxide; Transition metals
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202106337

Li‐rich Mn‐based oxides (LRMOs) are promising cathode materials for next‐generation lithium‐ion batteries (LIBs) with high specific energy (≈900 Wh kg−1) because of anionic redox contribution. However, LRMOs suffer from issues such as irreversible release of lattice oxygen, transition metal (TM) dissolution, and parasitic cathode–electrolyte reactions. Herein, a facile, scalable route to build homogenous and ultrathin Li2TiO3 (LTO) coating layer on the primary particles of LRMO through molten salt (LiCl) assisted solid–liquid reaction between TiO2 and Li1.08Mn0.54Co0.13Ni0.13O2 is reported. The prepared LTO‐coated Li1.08Mn0.54Co0.13Ni0.13O2 (LTO@LRMO) exhibits 99.7% capacity retention and 95.3% voltage retention over 125 cycles at 0.2 C, significantly outperforming uncoated LRMO. Combined characterizations of differential electrochemical mass spectrometry, in situ X‐ray diffraction, and ex situ X‐ray photoelectron spectroscopy evidence significantly suppressed oxygen release, phase transition, and interfacial reactions. Further analysis of cycled electrodes reveals that the LTO coating layer inhibits TM dissolution and prevents the lithium anode from TM crossover effect. This study expands the primary particle coating strategy to upgrade LRMO cathode materials for advanced LIBs. A facile molten LiCl assisted solid–liquid reaction is proposed to coat Li2TiO3 on primary particles of Li‐rich Mn‐based cathode materials. The coated cathode shows improved cycling stability and suppressed voltage decay due to decrease of oxygen loss, transition metal dissolution, and side reactions with electrolyte.