Mixed-metal MOF-derived Co–Mn–O hollow spheres as anodes for lithium storage

Abstract A Co–Mn–O/C composite is obtained by incorporating two metal ions from Co(Ac)2 and Mn(Ac)2 into a mixed-metal–organic framework (MOF) followed by high-temperature carbonization in air. The Co–Mn–O/C composite has a unique hollow-sphere structure with the shells constructed with Co–Mn–O grains embedded in an amorphous carbon matrix, which combines the advantage of efficient strain absorption and high conductivity . As a modulator, acetic acid has a large influence on the particle size and surface area of the Co–Mn–O/C hollow spheres that further affect their electrical properties, and an optimum Co:Mn ratio can result in greatly enhanced electrochemical performances. More importantly, the metallic Co nanoparticles in the Co–Mn–O/C composite also have the impact on adjusting the solid electrolyte interphase (SEI) layer, which helps in maintaining high morphological integrity and considerable electrochemical performance. At an optimum Co:Mn ratio, the Co–Mn–O/C electrode produces outstanding performance in both cycle and rate tests. A high-rate capacity of 1088.5 mAh g −1 is observed after 600 cycles at 1000 mA g−1 and a capacity of 775.9 mAh g−1 is reserved even after the current density rise to 8000 mA g−1. The Co–Mn–O/C composite is expected to serve as a low-cost and high-performance anode for lithium-ion batteries.