Multi-scale design of three-dimensional highly-conductive spherical Li-rich layered manganese oxide toward long-term stable cyclability

Abstract

The improvement of the cyclability and voltage decay of Li-rich layered manganese oxides (LLMOs) is crucial for developing Li-rich-based high energy density Li-ion batteries. However, the electron/ion transport mismatch and constant corrosion induced by the electrolyte remain huge challenges. In this work, we design a 3D highly conductive spherical structure using COMSOL simulations and synthesize a lithium silicate and graphene cocoated LLMO with high tap density by using liquid polysiloxane as the silicon source. Their synergistic effects reduce the activation energy in the lithiation/delithiation process, decrease the polarization, improve the thermal stability, and hinder the dissolution of transition metal ions in the material, thereby enhancing the electrochemical performance of the composite. After 200 cycles, the discharge capacity of the cocoated material is 212.9 mAh g−1 (91.3% capacity retention), the discharge specific energy reaches 713.5 Wh kg−1, and the discharge middle voltage increases by 0.1 V relative to the pristine sample after 200 cycles. The 3D structural design and multiscale modifications described herein greatly facilitate the commercialization of lithium-rich layered manganese oxides as cathode materials for next-generation Li-ion batteries with high energy density.