Carbon nanoparticle-entrapped macroporous Mn3O4 microsphere anodes with improved cycling stability for Li-ion batteries

Abstract

Manganese oxide (Mn3O4) has garnered substantial attention as a low-cost, environment-friendly anode material. It undergoes a conversion reaction involving the formation of Li2O and metallic Mn to provide high-energy Li-ion batteries. However, its low electrical conductivity and significant volume change reduce its capacity during the initial lithiation/delithiation, hindering its practical application. To improve the cycle performance, we propose a new composite structure wherein we entrap carbon nanoparticles in macroporous Mn3O4 microspheres with a unique maze-like porous interior. We fabricate the Mn3O4/C composites using a scalable two-step process involving the thermal decomposition of MnCO3 in water vapor and mixing in a carbon-dispersed solution. The fabricated Mn3O4/C composites with varying carbon contents exhibit a high maximum discharge capacity retention of 86% after 50 cycles, compared to the 18% given by bare Mn3O4. The entrapped carbon nanoparticles improve the cycle performance both electrochemically and physically. The microstructure of the composite particles and the fabrication process developed in this study will help improve the performance of other conversion-type anode materials that suffer from cycle degradation, including inexpensive transition metal oxides and sulfides.