Construction of unique heterogeneous cobalt–manganese oxide porous microspheres for the assembly of long-cycle and high-rate lithium ion battery anodes

Abstract

Porous (Co, Mn)(Co, Mn)₂O₄-based microspheres (CM-11-Ms) and core–shell microspheres (CM-11-CSMs) were firstly synthesized via controlled pyrolysis of CoMn-precursor microspheres at different temperatures under nitrogen. During pyrolysis of the CoMn-precursor, the carbon derived from hexamethylenetetramine and polyethylene glycol transforms part of (Co, Mn)(Co, Mn)₂O₄ into MnO and Co₃O₄. As an anode for lithium ion batteries, CM-11-Ms exhibits a specific capacity of 745 mA h g⁻¹ after 650 cycles at 1 A g⁻¹, while CM-11-CSMs exhibits an enhanced lithium storage capacity of 2175.8 mA h g⁻¹ even after 1000 cycles at 1 A g⁻¹ without an evident capacity decay. The improved electrochemical properties could be attributed to the unique core–shell structure that accommodates the volume expansion during cycling, the high-rate lithiation-induced reactivation, and the synergy effects among (Co, Mn)(Co, Mn)₂O₄, Co₃O₄, and MnO.