High-Entropy Rock-Salt Surface Layer Stabilizes the Ultrahigh-Ni Single-Crystal Cathode

• Published in: ACS nano Vol. 18; no. 49; pp. 33706 - 33717
• Main Authors: Xu, Zhongxing, Chen, Xinghan, Fan, Wenguang, Zhan, Minzhi, Mu, Xulin, Cao, Hongbin, Wang, Xiaohu, Xue, Haoyu, Gao, Zhihai, Liang, Yongzhi, Liu, Jiajie, Tan, Xinghua, Pan, Feng
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 10.12.2024
• Subjects: lithium-ion batteries; ultrahigh-Ni; layered oxide; single-crystalline cathodes; high-entropy
• ISSN: 1936-0851; 1936-086X; 1936-086X
• DOI: 10.1021/acsnano.4c13911

Single-crystalline Ni-rich layered oxides are one of the most promising cathode materials for lithium-ion batteries due to their superior structural stability. However, sluggish lithium-ion diffusion kinetics and interfacial issues hinder their practical applications. These issues intensify with increasing Ni content in the ultrahigh-Ni regime (≥90%), significantly threatening the practical viability of the single-crystalline strategy for ultrahigh-Ni layered oxide cathodes. Herein, by developing a high-entropy coating strategy, we successfully constructed an epitaxial lattice-coherent high-entropy rock-salt layer (∼3 nm) via Zr and Al doping on the surface of the single-crystalline cathode LiNi0.92Co0.05Mn0.03O2 through an in situ modification process. The surface high-entropy rock-salt layer with tailored Ni valence and lattice coherence not only greatly improves lithium-ion diffusion kinetics but also suppresses interface parasitic reactions and surface structural degradations. The high-entropy surface layer-stabilized ultrahigh-Ni single-crystalline cathode (SC-Ni92-ZA) demonstrates significantly improved rate and cycling performances (127.5 mAh g–1 at 20C, capacity retention of 74.9% after 500 cycles at 1C) in a half-cell. The SC-Ni92-ZA exhibits a capacity retention of 87.1% after 600 cycles at 1C in a full-cell. This epitaxial lattice-coherent high-entropy coating strategy develops a promising avenue for developing high-capacity, long-life cathode materials.