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

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. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The Co-Mn-O/C composite with a unique hollow-sphere structure shows excellent electrochemical performance, especially at the optimal Co:Mn ratio. The influence of acetic acid as a modulator on particle size and surface area further enhances the electrical properties of the Co-Mn-O/C hollow spheres.