Crack-free single-crystalline Co-free Ni-rich LiNi0.95Mn0.05O2 layered cathode

• Published in: eScience (Beijing) 2022-01, Vol.2 (1), p.116-124
• Main Authors: Ni, Lianshan, Guo, Ruiting, Fang, Susu, Chen, Jun, Gao, Jinqiang, Mei, Yu, Zhang, Shu, Deng, Wentao, Zou, Guoqiang, Hou, Hongshuai, Ji, Xiaobo
• Format: Article
• Language: English
• Subjects: Co-free Ni-rich cathodes; Cycling stability; H2↔H3 phase transition; Intergranular microcracking; Single-crystalline
• ISSN: 2667-1417; 2667-1417
• DOI: 10.1016/j.esci.2022.02.006

The rapid growth in global electric vehicles (EVs) sales has promoted the development of Co-free, Ni-rich layered cathodes for state-of-the-art high energy-density, inexpensive lithium-ion batteries (LIBs). However, progress in their commercial use has been seriously hampered by exasperating performance deterioration and safety concerns. Herein, a robust single-crystalline, Co-free, Ni-rich LiNi0.95Mn0.05O2 (SC-NM95) cathode is successfully designed using a molten salt-assisted method, and it exhibits better structural stability and cycling durability than those of polycrystalline LiNi0.95Mn0.05O2 (PC-NM95). Notably, the SC-NM95 cathode achieves a high discharge capacity of 218.2 mAh g−1, together with a high energy density of 837.3 ​Wh kg−1 ​at 0.1 C, mainly due to abundant Ni2+/Ni3+ redox. It also presents an outstanding capacity retention (84.4%) after 200 cycles at 1 ​C, because its integrated single-crystalline structure effectively inhibits particle microcracking and surface phase transformation. In contrast, the PC-NM95 cathode suffers from rapid capacity fading owing to the nucleation and propagation of intergranular microcracking during cycling, facilitating aggravated parasitic reactions and rock-salt phase accumulation. This work provides a fundamental strategy for designing high-performance single-crystalline, Co-free, Ni-rich cathode materials and also represents an important breakthrough in developing high-safe, low-cost, and high-energy LIBs. Robust single-crystalline Co-free Ni-rich LiNi0.95Mn0.05O2 (SC-NM95) cathode successfully designed by molten salt-assisted method exhibits the enhanced structural stability and cycling durability compared with that of polycrystalline LiNi0.95Mn0.05O2 (PC-NM95) cathode. [Display omitted] •Single-crystalline Co-free Ni-rich LiNi0.95Co0.05O2 cathode was firstly designed and systematically explored.•The SC-NM95 cathode presents outstanding structural stability and cycling durability.•The performance degradations of PC-NM95 were attributed to the microcracking formation and structural transformations.•It provides insights into the fundamental design of high-performance single-crystalline Co-free Ni-rich cathodes.