Mesoporous MnO2 based composite electrode for efficient alkali-metal-ion storage

The mesoporous delta-MnO2-based nanostructure is elaborately designed for overcoming the main bottleneck problems for lithium and sodium storage. Based on density functional theory, MnO2 composite possesses high binder energy and low migration barrier for energy storage, which are beneficial for improving sluggish electrochemical kinetics. Additionally, dendritic metal growth is inhibited via electrostatic force. All these merits ensure the exceptional rate and cycle performance during cycling process. Coupling MnO2 with Ni-Co-Oxide promotes homogeneous nucleation sites, guiding Li/Na metal deposition/exfoliation and suppressing dendritic lithium/sodium growth. Simultaneously, abundant grain boundaries between MnO2-C and Ni-Co-Oxide bring more enriched sites for fast ion diffusion and pseudo-capacitive storage processes. The enriched surface defects lower the impedance to achieve fast transport kinetics. Making full use of the structure, component and composition, such MnO2 based electrodes exhibit superior cycle ability and high capacity for both lithium and sodium storage. This work supplies the robust SEI design protocol and sheds new light on developing stable lithium and sodium ion batteries.