A green water-induced spinel heterostructure interface enabling high performance lithium and manganese rich oxides

Abstract

Lithium and manganese rich oxides (LMROs) are promising candidates for next-generation high-energy lithium-ion batteries. However, intrinsic problems associated with low initial coulombic efficiency and inferior rate capability impede the commercial application of LMROs. A conformal and uniform surface coating on LMROs can effectively suppress these drawbacks. In this work, we propose a mild and green method to introduce a spinel heterostructure layer on the surface of LMROs via a simple Li⁺/H⁺ ion exchange reaction in pure H₂O. The transformed spinel heterostructure layer is intimately integrated with the bulk core and displays better structural stability and high diffusion dynamic kinetics for Li⁺, which contributes to sustaining superior electrochemical performances. The modified LMRO delivers a high initial coulombic efficiency of 87.1%, specific capacity of 150 mA h g⁻¹ at 1.6 A g⁻¹ and 89% capacity retention after 200 cycles at 0.5C, while they are 78.5%, 127 mA h g⁻¹ and 79% for the original LMRO. The method is controllable, cost-effective, and environmentally friendly, and has great potential for commercial application. This work also proposes a new viewpoint for uncovering the mechanism of introducing spinel components into LMROs through a hydrothermal process.