Yolk–shell structured MnCo2O4.5 nanospheres for high performance lithium-ion battery anodes

Abstract

A facile approach is reported for preparing defect-rich yolk–shell MnCo₂O_4.5 nanospheres by simply tuning the Mn/Co ratio. Benefiting from their multivalent redox chemistry, Mn–Co bimetallic oxides exhibit rich electrochemically active sites as well as favorable reaction kinetics. The core–void–shell architecture enables efficient electrolyte penetration, short ion/electron transport pathways, and effective buffering of the volume variation associated with conversion reactions during repeated lithiation/delithiation. As a lithium-ion battery anode, the optimized MnCo₂O_4.5-5 sample (Co/Mn = 5 : 1) delivers a reversible capacity of 578.5 mAh g⁻¹ after 400 cycles at 2 A g⁻¹, together with excellent rate capability of 680.9 mAh g⁻¹ at 5 A g⁻¹. This work demonstrates that integrating compositional synergy and defect regulation with a mechanically adaptive yolk–shell configuration provides an effective pathway to simultaneously improve electrochemical kinetics and structural robustness, offering a promising design paradigm for high performance conversion-type anodes.