Enhancing structural integrity and performance of Li-Rich Mn-based cathode materials via multi-component surface engineering

Abstract

High energy density Li-rich Mn-based cathode materials (LMR) are the research hotspot of cathode materials for new generation of Li-ion batteries. Unlike the conventional cationic oxidation/reduction reaction mechanism, the ultrahigh specific capacity of this material primarily stems from the participation of partial lattice oxygen in the electrochemical reaction. However, the accompanying irreversible oxygen release can lead to structural transformation and interfacial side reactions, thereby accelerating voltage and capacity decay. Therefore, we constructed a surface multicomponent integration strategy integrating oxygen vacancies, spinel/layered heterostructures, and carbon nano-coatings through a scalable carboxymethyl cellulose (CMC)-assisted interfacial engineering strategy. This surface multi-component modified layer is perfectly compatible with the main structure, effectively stabilizes the surface structure, avoids direct contact between the main structure of the material and the electrolyte, reduces side reactions between the electrode surface and the electrolyte, inhibits the formation of the inert cathode electrolyte interface (CEI), and reduces the dissolution of the transition metal ions during the cycling. In addition, spinel phases with 3D Li-ion diffusion channels and carbon nano-coatings with fast electron conduction paths effectively improve the electronic and ionic conductivity of the electrode material surface. Electrochemical performance tests show that the initial coulombic efficiency of the surface-modified material is increased from 72.6 % to 86.2 %, and the capacity retention is 80.7 % after 300 cycles at 1 C rate, and the rate performance is also significantly improved, which indicates that this surface multicomponent integration strategy effectively improves the comprehensive electrochemical performance of the material.