Multiphase Manganese Oxides with Micron Cage Structure as High-Performance Cathode Material for AZIBs

Aqueous Zinc ion batteries (AZIBs) have become one of the most prospective energy storage devices. However, Mn-based AZIBs suffer from a bottleneck, that is, Mn³⁺ disproportionation and Jahn-Teller distortion can induce Mn²⁺ dissolution and irreversible phase changes, greatly deteriorating the cycling lifetime. In this work, we report an available cooperation strategy of multiphase manganese oxides (N-Mn₃O₄/MnO) via a two-step solvothermal method to obtain an attractive cathode for AZIBs. The high reversible specific capacity and superior rate performance of this cathode result from the facile charge transfer channel and ions (Zn²⁺ and H⁺) insertion in the porous hybrids featuring phase stability behavior caused by the available synergistic effects of N-doping, heterojunction and porous micron cage. (I) the micron-cage structure is favorable for e^- and Li⁺ transfer; (II) The construction of heterostructures is beneficial to improving the electronic conductivity, because the interface effect and built-in electric field of heterostructures is capable of simultaneously accelerating the transport of ions and electrons; (III) N-C and N-Mn bonds effectively overcome the inherent activation barrier and promote the reaction kinetics. These results all demonstrate the advantages of N-Mn₃O₄/MnO of the hybrid material. The meaning of this work is to put forward a compositional and structural design strategy for the Zn-Mn system for the low-cost and high-performance aqueous rechargeable AZIBs.