Mitigating fast-charging degradation in Ni-rich cathodes via enhancing kinetic-mechanical properties

Abstract

Ni-rich cathode materials are essential for enhancing the performance of lithium-ion batteries (LIBs) in electric vehicles (EVs), particularly concerning extreme fast charging (XFC) and durability. While much of studies shine a spotlight on Li plating on the anode to improve rate capability, there is a critical lack of studies addressing the combination of kinetic improvements and mechanical strength of cathode materials under XFC conditions. In this work, Mg/Ti co-doped Ni-rich LiNi0.88Co0.09Mn0.03O2 (MT-NCM) was successfully synthesized to address structural challenges associated with high-rate cycling. The results demonstrate that the stronger Ti–O bond contributes to the enhanced mechanical strength of secondary grains, which effectively alleviates microcrack formation during fast charging. Additionally, the detrimental phase transitions and internal strain as well as parasitic reactions of MT-NCM are significantly suppressed due to the synergistic effect of the dual dopants, ensuring excellent Li-ion transport kinetics compared to pristine NCM (P-NCM). Consequently, MT-NCM achieves remarkable high-rate cycling performance, retaining 88.04% of its initial capacity at 5 C and superior discharge capacity over 175 mA h g−1 even at 10 C. This work highlights the potential of optimizing the kinetic-mechanical properties of Ni-rich cathodes, providing a viable approach for the development of XFC LIBs with improved durability for EV applications.