Expandable Fast Li-Ion Diffusion Network of Li-Rich Mn-Based Oxides via Single-Layer LiCo(Ni)O₂ Segregation.

Abstract

Li-rich Mn-based cathode materials exhibit a remarkable reversible specific capacity exceeding 250 mAh g^-1, positioning them as the preferred choice for the next generation of high-energy density lithium-ion battery cathode materials. However, their inferior rate and cycling performance pose significant challenges. In this context, a Li-rich material incorporating an expanded fast Li-ion diffusion network has been successfully synthesized. This advancement involves the introduction of a single-layer of LiCo(Ni)O₂ with high Li-ion diffusion coefficients into the crystal structure of Li-rich cathode, thereby enhancing the rate performance, achieving an impressive capacity of 212 mAh g^-1 at 5 C. Furthermore, the single-layer LiCo(Ni)O₂ can effectively isolates Li₂MnO₃ phase domains, thereby enhancing the structural stability during the anion redox process, consequently extending the electrochemical stability limits. Operating within a voltage range of 2.1-4.6 V, the capacity retention reaches 80% after 400 cycles, with a voltage decay of merely 0.74 mV per cycle. This innovative utilization of an expanded fast Li-ion diffusion network provides invaluable insights that will guide the development of strategies aimed at unlocking rate capability in layered oxide cathode materials.