Thermal Expansion Neutralization Enhancing the Cycling Stability of Ni-Rich LiNi0.6Co0.2Mn0.2O2 Cathode Material

Kai Du; Maokun Wu; Xinhong Hu; Wei-Hua Wang; Du Pan; Zhenbo Wang; Yanfeng Yin; Huiling Zhao; Ying Bai

doi:10.1021/acsami.3c06932

Thermal Expansion Neutralization Enhancing the Cycling Stability of Ni-Rich LiNi_0.6Co_0.2Mn_0.2O₂ Cathode Material

ACS Appl Mater Interfaces. 2023 Jul 19;15(28):33703-33711. doi: 10.1021/acsami.3c06932. Epub 2023 Jul 9.

Authors

Kai Du^{1

2}, Maokun Wu³, Xinhong Hu¹, Wei-Hua Wang³, Du Pan¹, Zhenbo Wang¹, Yanfeng Yin¹, Huiling Zhao^{1

2}, Ying Bai^{1

2}

Affiliations

¹ International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, School of Physics and Electronics, Henan University, Kaifeng 475004, P. R. China.
² Academy for Advanced Interdisciplinary Studies, Henan University, Kaifeng 475004, P. R. China.
³ Department of Electronic Science and Engineering, Tianjin Key Laboratory of Photo-Electronic Thin Film Device and Technology, Nankai University, Tianjin 300071, P. R. China.

PMID: 37424078
DOI: 10.1021/acsami.3c06932

Abstract

As promising cathode candidates with advantageous capacity and price superiority for lithium-ion batteries, Ni-rich materials are severely impeded in the practical application due to their poor microstructural stability induced by the intrinsic Li⁺/Ni²⁺ cation mixing and mechanical stress accumulation upon cycling. In this work, a synergetic approach is demonstrated to improve the microstructural and thermal stabilities of Ni-rich LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) cathode material through taking advantage of the thermal expansion offset effect of the LiZr₂(PO₄)₃ (LZPO) modification layer. The optimized NCM622@LZPO cathode exhibits a significantly enhanced cyclability with a capacity retention of 67.7% after 500 cycles at 0.2 C and delivers a specific capacity of 115 mAh g^-1 with a capacity retention of 64.2% after 300 cycles under 55 °C. Exploiting the chemical environment analysis of the Ni element detected by the synchrotron radiation technique, it is found that the mixing degree of Li⁺/Ni²⁺ cations in the bulk Ni-rich material can be effectively depressed through interfacial Zr⁴⁺ doping during the preparation of the LZPO-modified material. Additionally, time- and temperature-dependent powder diffraction spectra were collected to monitor the structure evolutions of pristine NCM622 and NCM622@LZPO cathodes in the initial cycles and under various temperatures, revealing the contribution of negative thermal expansion LZPO coating in promoting microstructural stability of the bulk NCM622 cathode. The introduction of NTE functional compounds might provide a universal strategy to address the stress accumulation and volume expansion issues of various cathode materials for advanced secondary-ion batteries.

Keywords: Ni-rich cathode; electrochemical performance; in situ XRD; lithium-ion batteries (LIBs); negative thermal expansion (NET); surface engineering.