Micro/nanostructured MnCo2O4.5 anodes with high reversible capacity and excellent rate capability for next generation lithium-ion batteries

Abstract

Lithium-ion batteries have already achieved great success in consumer electronics. However, the electrochemical characteristics of the existing electrodes have constrained their widespread applications in electric vehicles, which need technical demands of high energy density and fast charging. Thus, it is highly desirable to explore high-performance electrodes with high reversible capacity and excellent rate capability. In this study, micro/nanostructured MnCo2O4.5 anodes were synthesized by hydrothermal treatment with the presence of positively charged poly(diallyldimethylammonium chloride). Physicochemical property studies suggested that the as-prepared MnCo2O4.5 of 2–5 µm in diameter was mainly composed of numerous nanoneedles, which were further comprised of many inter-connected nanoparticles. Also, poly(diallyldimethylammonium chloride) played the key roles as morphology controlling agent for the formation of the unusual MnCo2O4.5 crystal phase. The unique properties of micro/nanostructured MnCo2O4.5 including multi-scale dimensions, mesoporous structure, and multivalent states guaranteed the superior electrochemical characteristics in the repeated charge-discharge cycles. When evaluated as anodes for electrochemical lithium storage, high reversible capacity and good cycling performance were demonstrated with a current density of 500 mA g−1 over 200 cycles. Even when tested at relatively high current densities of 1000, 2000 and 3000 mA g−1, the average reversible capacities were also achieved at about 1441, 1213 and 966 mAh g−1, respectively. The achieved electrochemical characteristics of MnCo2O4.5 anodes were proved to be better than many binary transition metal oxides or comparable with high-capacity Si-based anodes. Overall, this study demonstrated micro/nanostructured MnCo2O4.5 as potential high-performance anodes for practical applications of next generation lithium-ion batteries.