Constructing a robust Li-rich Mn-based oxide cathode by tailoring redox couples via multifunctional Bi2O3 modification

Due to the remarkable high energy density and high operating voltage, lithium-rich layered oxides (LLOs) are emerging as one of the most promising candidates for high-specific-energy cathode materials . However, the poor cycling stability and severe voltage degradation are key barriers, which limit their practical application. In this paper, Bi 2 O 3 modified Li 1.2 Mn 0.6 Ni 0.2 O 2 (LMO@BO) is developed to address these challenges. The uniform and dense coating is constructed on the surface of LMO, which utilizes number of oxygen vacancies in its crystal structure to mediate the release of O 2 and mitigate the irreversible loss of lattice oxygen, further suppress the phase transformation during the cycling process. Specifically, the specific discharge capacity of the LMO@BO cathode maintains 197.9 mAh g −1 at 1C with capacity retention rate of 96.3 % after 200 cycles(vs. unmodified LMO with capacity of 147.5 mAh g −1 and retention rate of 80.1 %. Meanwhile, a small amount of Bi 3+ is doped into the bulk phase to broaden the Li  +  migration channel, resulting in an efficient Li + diffusion. Overall, Bi 2 O 3 modified LMO sample is conducive to meeting the requirements of high energy density for lithium-ion batteries applications.