Achieving thermodynamic stability of single-crystal ultrahigh-nickel cathodes via an alcohol-assisted mechanical fusion

• Published in: Journal of energy chemistry 2024-12, Vol.99, p.580-592
• Main Authors: Zhang, Zhi, Liu, Tiancheng, Gao, Ce, Liu, Yun, Kuai, Hailan, Du, Hongli, You, Wanli, Huang, Xiaobing, Shen, Jixue, Huang, Haitao, Su, Yuefeng, Chen, Lai
• Format: Article
• Language: English
• Subjects: Cycling stability; LiFePO4 nano-particles; Single-crystal LiNi0.92Co0.04Mn0.04O2; Thermal stability; Ultrahigh voltage
• ISSN: 2095-4956
• DOI: 10.1016/j.jechem.2024.07.041

Well-designed LiNi0.92Co0.04Mn0.04O2@LiFePO4 (SC-N92@LFP) is successfully prepared by a mechanical fusion aided by alcohol method. Remarkably, the SC-N92@LFP exhibits significant electrochemical performance and thermodynamic stability. [Display omitted] Elevating the operating voltage is an effective approach to improve the reversible capacity of ultra-high nickel layered oxide cathode LiNixCoyMnzO2 (NCM, x ≥ 0.8) and solve the “range anxiety” confusion of electric vehicles. However, the undesirable surface reconstruction induced by the high cut-off voltage has a fatal impact on the thermodynamic stability of the material, inevitably leading to fast capacity degradation. Herein, a mechanical fusion aided by alcohol is suggested to create a stable olivine structure for the single-crystal (SC) ultrahigh-nickel cathode LiNi0.92Co0.04Mn0.04O2. The addition of nanoparticles effectively bridges the void of SC-NCM, builds an ideal particle grading, and significantly raises the cost efficiency, as well as promotes the cycling stability and safety of the full cell. Remarkably, the layered/olivine mixture forms a perfect shield by lowering the surface area between the NCM cathode and electrolyte, hence mitigating side reactions and contributing to an incredibly thin and stable cathode/electrolyte interface. Furthermore, the thermodynamic stability of highly delithiated NCM is improved, as both the particle cracks and structural degradation are simultaneously postponed. Consequently, the maximum temperature of the single-crystal LiNi0.92Co0.04Mn0.04O2@LiFePO4‖graphite pouch full cell is dramatically reduced from 599.4 to 351.4 °C, and the full cell achieves 88.2% capacity retention after 800 cycles, demonstrating excellent thermal stability and cycling stability. This facile strategy provides a feasible technical reference for further exploiting the ultrahigh-capacity, high-safety, and long-life Ni-rich cathode for commercial application of lithium-ion batteries (LIBs).