Integrated Surface Modulation of Ultrahigh Ni Cathode Materials for Improved Battery Performance

• Published in: Small methods 2023-07, Vol.7 (7), p.e2300280-n/a
• Main Authors: Qi, Mu‐Yao, Zhang, Si‐Dong, Guo, Sijie, Ji, Peng‐Xiang, Mao, Jian‐Jun, Wu, Ting‐Ting, Lu, Si‐Qi, Zhang, Xing, Chen, Shu‐Guang, Su, Dong, Chen, Guan‐Hua, Cao, An‐Min
• Format: Article
• Language: English
• Subjects: gradient lattice doping; high‐energy Li‐ion batteries; Li2ZrO3; Ni‐rich layered oxide cathodes; surface modulation; uniform Zr nanoshells
• ISSN: 2366-9608; 2366-9608
• DOI: 10.1002/smtd.202300280

Ni‐rich layered cathodes with ultrahigh nickel content (≥90%), for example LiNi0.9Co0.1O2 (NC0.9), are promising for next‐generation high‐energy Li‐ion batteries (LIBs), but face stability issues related to structural degradation and side reactions during the electrochemical process. Here, surface modulation is demonstrated by integrating a Li+‐conductive nanocoating and gradient lattice doping to stabilize the active cathode efficiently for extended cycles. Briefly, a wet‐chemistry process is developed to deposit uniform ZrO(OH)2 nanoshells around Ni0.905Co0.095(OH)2(NC0.9‐OH) hydroxide precursors, followed by high temperature lithiation to create reinforced products featuring Zr doping in the crust lattice decorated with Li2ZrO3 nanoparticles on the surface. It is identified that the Zr4+ infiltration reconstructed the surface lattice into favorable characters such as Li+ deficiency and Ni3+ reduction, which are effective to combat side reactions and suppress phase degradation and crack formation. This surface control is able to achieve an optimized balance between surface stabilization and charge transfer, resulting in an extraordinary capacity retention of 96.6% after 100 cycles at 1 C and an excellent rate capability of 148.8 mA h g−1 at 10 C. This study highlights the critical importance of integrated surface modulation for high stability of cathode materials in next‐generation LIBs. Uniform ZrO(OH)2 nanocoatings on Ni‐rich hydroxide precursors are achieved via a decomposition‐promoted precipitation (DPP) protocol. Gradient surface Zr doping and refined microstructure in products are achieved through the following lithiation. This integrated modulation suppresses side reactions and deleterious phase transition. Consequently, the cell delivers a high‐capacity retention of 87.2% over 200 harsh cycles at 0.2 C.