Ultrathin Li-Si-O Coating Layer to Stabilize the Surface Structure and Prolong the Cycling Life of Single-Crystal LiNi0.6Co0.2Mn0.2O2 Cathode Materials at 4.5 V

Guangxin Li; Longzhen You; Ya Wen; Congcong Zhang; Ben Huang; BinBin Chu; Jian-Hua Wu; Tao Huang; Aishui Yu

doi:10.1021/acsami.0c22356

Ultrathin Li-Si-O Coating Layer to Stabilize the Surface Structure and Prolong the Cycling Life of Single-Crystal LiNi_0.6Co_0.2Mn_0.2O₂ Cathode Materials at 4.5 V

ACS Appl Mater Interfaces. 2021 Mar 10;13(9):10952-10963. doi: 10.1021/acsami.0c22356. Epub 2021 Feb 23.

Authors

Guangxin Li¹, Longzhen You², Ya Wen³, Congcong Zhang¹, Ben Huang², BinBin Chu², Jian-Hua Wu³, Tao Huang¹, Aishui Yu^{1

2}

Affiliations

¹ Laboratory of Advanced Materials, Institute of New Energy, Fudan University, 2205, Songhu Road, Shanghai 200438, China.
² Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, 2205, Songhu Road, Shanghai 200438, China.
³ Jiangmen KanHoo Industry Co., Ltd., 22, South Jiaoxing Road, Jiangmen, Guangdong 529040, China.

PMID: 33620199
DOI: 10.1021/acsami.0c22356

Abstract

Single-crystal LiNi_1-x-yCo_xMn_yO₂ cathode materials can effectively suppress intergranular cracks that usually is seen in commercial polycrystal LiNi_1-x-yCo_xMn_yO₂ cathode materials. However, the surface structure degradation for single-crystal LiNi_1-x-yCo_xMn_yO₂ cathode materials is still aggravated at a higher cutoff voltage (over 4.5 V). In this work, we prepare single-crystal LiNi_0.6Co_0.2Mn_0.2O₂ cathode materials via a solid-state method and then coat an ultrathin Li-Si-O layer on their surface by a wet coating method. The results show that the single-crystal LiNi_0.6Co_0.2Mn_0.2O₂ cathode materials with a Li-Si-O coating layer deliver excellent cycling performance even at a higher cutoff voltage of 4.5 V. The optimized Li-Si-O-modified sample displays a capacity retention of 90.6% after 100 cycles, whereas only 68.0% for unmodified single-crystal LiNi_0.6Co_0.2Mn_0.2O₂. Further analysis of the cycled electrodes reveals that the surface structure degradation is the main reason for the decrease of electrochemical performance of single-crystal LiNi_0.6Co_0.2Mn_0.2O₂ at a high voltage (4.5 V). In contrast, with Li-Si-O coating, this phenomenon can be suppressed effectively to maintain interfacial stability and prolong the cycling life.

Keywords: LiNi0.6Co0.2Mn0.2O2; degradation mechanisms; high voltage; high-nickel cathode materials; single-crystal NCM cathode materials; surface stability; ultrathin Li−Si−O coating layer.