Mn-based Li-rich layered oxides obtained by double-surface modification engineering as high performance cathode materials for lithium-ion batteries

Abstract

Lithium-rich layered oxides (LLOs) are notable for their excellent specific capacity of over 250 mA h g⁻¹ and potentially high energy density properties. However, their possible irreversible delocalization of lattice oxygen during cycling and their resulting phase transitions and structural collapses severely degrade their multiplicity performance and cycling stability. In this paper, the surface of lithium-rich manganese-based materials was dual-treated with a combination of a lithium-ion conductor Li₂O-2B₂O₃ (LBO) coating and oxygen vacancy modification, which effectively improved the multiplicity performance and cycling stability by constructing a three-dimensional channel through cladding, as well as generating a surface spinel phase in situ through vacancy treatment, which suppressed the irreversible degradation of lattice oxygen. After 100 cycles at 0.2 C, the discharge specific capacity of double-surface-modified Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ (LB-M) reached 242.8 mA h g⁻¹ with a capacity retention rate of 96.5%. Finally, the mechanism of performance enhancement was analyzed by XRD and Raman refinement and combined with the calculation of the diffusion coefficient. Double-surface modification engineering also provides a new idea for the modification of Li-rich manganese-based materials.