Mitigating magnetic frustration to improve single-crystalline nonstoichiometric LiNiMnO for lithium-ion batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2024-09, Vol.12 (35), p.23454-2346
• Main Authors: Ding, Guoyu, Wang, Shizhou, Huang, Xinhui, Zhao, Qiancheng, Peng, Yiyang, Wu, Zhonghan, Jiang, Na, Liu, Kuiming, Zhang, Yudong, Hou, Zhichen, Yang, Wutong, Yu, Meng, Liu, Fangming, Cheng, Fangyi
• Format: Article
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d4ta03933e

Single-crystalline Co-free layered nickel-rich oxide LiNi 1− x Mn x O 2 ( x ≤ 0.1) is an appealing cathode material but suffers from significant structural degradation that correlates with the Li + /Ni 2+ cation mixing induced by the magnetic frustration. In this study, we propose a molten salt-assisted synthesis and a Li-refeeding strategy to prepare a single-crystalline slightly Li-rich Li 1.06 Ni 0.90 Mn 0.04 O 2 cathode material. A small amount of lithium doping into the transition metal layer increases the average valence of Ni and Mn, and reduces the magnetic frustration, as evidenced by electron energy loss spectroscopy and superconducting quantum interference device. Benefiting from mitigated magnetic frustration, the single-crystalline slightly Li-rich Li 1.06 Ni 0.90 Mn 0.04 O 2 delivers a high specific capacity of 214.8 mA h g −1 at 0.1 C, and a remarkable capacity retention of 93.4% after 100 cycles at 5C in a coin cell, and achieves a superior long-term stability of 400 cycles with 79.4% capacity retention at 2C in a 362.9 mA h pouch full cell. The results validate the mitigation of magnetic frustration by tuning the Li stoichiometry to reinforce the structural stability for the design of better Co-free nickel-rich oxide cathode materials. A molten salt-assisted synthesis and Li-refeeding strategy is applied to prepare single-crystalline slightly Li-rich Li 1.06 Ni 0.90 Mn 0.04 O 2 with low magnetic moment and mitigated Li + /Ni 2+ cation mixing, which enhances cycling performance.