Liu, H.; Li, Y.; Deng, B.; Li, H.; Hua, W.; Wong, D.; Xiang, W.; Xiao, Y.; Knapp, M.; Ehrenberg, H.; Indris, S.: Balancing the structural order - redox chemistry via lithium content for stable layered oxide cathodes. Chemical Engineering Journal 536 (2026), p. 175773/1-9
10.1016/j.cej.2026.175773
Abstract:
The electrochemical performance of layered transition-metal oxides is highly sensitive to lithium content, yet the underlying structural and redox mechanisms remain elusive. Here we systematically investigated this relationship using a series of Li1+x[Ni0.5Mn0.5]1 xO2 cathodes with tunable lithium content (x = 0, 0.05, 0.10, 0.15, 0.20). Increasing lithium content concertedly reduces lattice parameters, suppresses cation mixing, promotes the formation of honeycomb superstructure, and drives the evolution of superstructure units from LiMn6 to LiNiMn5. In parallel, the surface atomic structure evolves from fully disordered to partially disordered and ultimately to an ordered layered arrangement. Despite these structural improvements, higher lithium content is associated with a marked increase in irreversible oxygen redox activity, as revealed by combined spectroscopic and electro-chemical analyses. Together, these findings establish lithium content as a key parameter governing the balance between structural order and redox reversibility. By optimizing this trade-off, we demonstrate a high-performance Li1.1Ni0.45Mn0.45O2 cathode that delivers a specific capacity of 228.0 mAh g 1 with 90.4% capacity retention after 100 cycles. Our findings provide valuable insights into the chemical composition design of high-energy-density, layered cathodes.