Abstract

Ni-rich layered oxide LiNi0.91Co0.06Al0.03O2 (NCA91) with high specific capacity has emerged as a leading cathode candidate for advanced lithium-ion batteries (LIBs). Nevertheless, increase in Ni content triggers structural instability and fast capacity degradation, which severely impedes the practical application of Ni-rich materials. Herein, a comprehensive study is conducted to explore the structural evolution and electrochemical behaviors of NCA91 cathodes with precisely tuned Li/TMs (transition metals) molar ratios spanning from 1.01 to 1.07. Results reveal that the NCA91 electrode with an optimal Li/TMs ratio of 1.03 exhibits outstanding structural integrity, coupled with remarkable cycling durability and rate capability. Specifically, the cathode with Li/TMs = 1.03 retains 88% of its initial capacity after 100 cycles at 1 C, and maintains ~130 mAh g−1 even at 10 C. This work establishes a quantitative structure–composition–performance correlation that offers critical design principles for developing ultrahigh-nickel cathode materials.

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