Molten Salt‐Assisted Synthesis of Single‐Crystalline Nonstoichiometric Li<sub>1+</sub><i><sub>x</sub></i>Ni<sub>1–</sub><i><sub>x</sub></i>O<sub>2</sub> with Improved Structural Stability
Guoyu Ding, Meng Yao, Jinhan Li, Tingting Yang, Yudong Zhang, Kuiming Liu, Xinhui Huang, Zhonghan Wu, Jiayu Chen, Ziyan Wu, Jiayong Du, Changru Rong, Qi Liu, Wei Zhang, Fangyi Cheng
Abstract
Abstract Cobalt‐free LiNiO 2 is an attractive cathode material with high energy density and low cost but suffers from severe structural degradation and poor performance. Here, a molten salt‐assisted synthesis combined with a Li‐refeeding strategy is proposed to obtain nonstoichiometric Li 1+ x Ni 1‐ x O 2 with submicron particle size and superior rate performance. The slightly Li‐rich and single‐crystalline characters inhibit Li + /Ni 2+ anti‐site defects and mitigates the undesirable phase evolution. Remarkably, single‐crystalline Li 1.045 Ni 0.955 O 2 exhibits a high specific capacity (218.7 mAh g −1 at 0.1 C), considerable rate capability (187.0 mAh g −1 at 5 C), and an initial Coulombic efficiency (89.62% at 0.1 C) in the 1.27 Ah pouch full cell employing the graphite anode, significantly outperforming near stoichiometric LiNiO 2 . Furthermore, the particulate morphology of Li 1.045 Ni 0.955 O 2 remains intact at charge voltages up to 4.8 V, whereas near stoichiometric LiNiO 2 features intragranular cracks and irreversible lattice distortion. This study underscores the value of molten salt‐assisted synthesis and Li‐refeeding modification to upgrade Ni‐based layered oxide cathode materials for advanced Li‐ion batteries.