Structural engineering of nickel-rich cathode material for improved cycling performance of lithium-ion batteries

Nickel-rich cathodes (NRCs) hold great promise for next-generation high-energy lithium-ion batteries (LIBs) due to high specific energy and low cost. However, the higher Ni content exacerbates the instability issues associated with structural degradation and side reactions during electrochemical cycling. Herein, we demonstrate the possibility of preparing NRCs, typically LiNi0.9Co0.05Mn0.05O2 (NCM9055), with much-improved mechanical and chemical stability based on the surface coating of the hydroxide precursors. Specifically, a conformal nanoshell containing both Al3+ and W6+ was first deposited around the precursor particles, and the following high-temperature lithiation produced the targeted NCM9055 with favorable structural features, where Al3+ existed as a bulk dopant to enhance the structural stability while the high-valent W6+ promoted the microstructural evolution into radially-architectured elongated primary particles. Such a structural engineering benefiting from the Al3+/W6+ co-modification endowed the prepared NCM9055 cathode (NCM9055-AlW) with much-improved cycling stability, as revealed by a high-capacity retention of 98.0% after 100 cycles (tested at 0.5 C, 4.3 V) as compared to only 79.0% for the pristine cathode without Al3+/W6+. The NCM9055-15AlW cathode also showed a high-rate capability with extraordinary structural stability against mechanical failure. Our study highlighted the enormous potential of precursor multi-element treatment as an effective tool in structural refinement of NRCs to circumvent their stability challenge for their applications in high-energy LIBs.