Mitigated lattice distortion and oxygen loss of Li-rich layered cathode materials through anion/cation regulation by Ti4+-substitution

Lithium-rich layered cathode material (LLM) can meet the requirement of power lithium-ion energy storage devices due to the great energy density. However, the de/intercalation of Li+ will cause the irreversible loss of lattice oxygen and trigger transition metal (TM) ions migrate to Li+ vacancies, resulting in capacity decay. Here we brought Ti4+ in substitution of TM ions in Li1.2Mn0.54Ni0.13Co0.13O2, which could stabilize structure and expand the layer spacing of LLM. Moreover, optimized Ti-substitution can regulate the anions and cations of LLM, enhance the interaction with lattice oxygen, increase Ni3+ and Co3+, and improve Mn4+ coordination, improving reversibility of oxygen redox activation, maintaining the stable framework and facilitating the Li+ diffusion. Furthermore, we found 5% Ti-substitution sample delivered a high discharge capacity of 244.2 mAh/g at 50 mA/g, an improved cycling stability to 87.3% after 100 cycles and enhanced rate performance. Thereby Ti-substitution gives a new pathway to achieve high reversible cycle retention for LLMs.