Enhanced lattice oxygen redox reversibility in cobalt-free lithium-rich Li1.2Ni0.2Mn0.6O2 cathode via Ti/Si dual modification

Lithium-rich manganese-based cathode materials, as promising candidates for next-generation high-energy–density lithium-ion batteries due to their high specific capacity (>250 mAh g−1) and cost-effectiveness, are limited by severe capacity decay and voltage fade driven by irreversible structural transitions and oxygen release during cycling. Here, we report a Ti/Si dual-element modification strategy for cobalt-free Li1.2Ni0.2Mn0.6O2 (LNMO) cathodes. The Ti/Si co-modified TS-LNMO cathode demonstrates superior structural stability and electrochemical performance. Bulk Ti4+ doping stabilizes the oxygen framework via robust Ti–O bonds and enhances the lattice oxygen redox reversibility, while an in situ formed Li2SiO3 layer suppresses interfacial side reactions, enhances lithium-ion diffusion, and prevents HF-induced erosion. As a result, the TS-LNMO cathode achieves 90 % capacity retention after 200 cycles at 0.5 C and maintains ∼80 % capacity in full cells cycled to 4.8 V. Additionally, the TS-LNMO cathode exhibits impressive rate performance even at a high rate of 5 C. This work offers an effective strategy for advancing cobalt-free, high-performance lithium-rich cathodes for sustainable energy applications.