Expanded spinel ZnxMn2O4 induced by electrochemical activation of glucose − mediated manganese oxide for stable cycle performance in zinc − ion batteries

Abstract

Rechargeable aqueous Zn − MnOx batteries show great potential for grid − scale storage due to cost − effectiveness and high safety. However, most of MnOx cathodes suffer from irreversible phase transformation into spinel ZnMn2O4 with reduced electrochemical activity after repeated charge/discharge cycles, leading to severe capacity decay. Herein, we reveal a strategic design utilizing glucose as the mediating agent to prepare nanostructured MnO/Mn3O4 material, which can be then transformed into lattice − expanded ZnxMn2O4 nanoparticles by electrochemical activation. The expanded structure of ZnxMn2O4 allows better accommodation of Zn2+ and H+ ions and undergoes reversible lattice expansion/contraction during charge/discharge process. Therefore, the lattice − expanded ZnxMn2O4 retains 121 mAh g−1 after 2000 cycles at 1 A g−1, exhibiting stable cycle performance in comparison with the parent MnO2 (63 mAh g−1) and well − crystalline ZnMn2O4 (58 mAh g−1). Moreover, through the comparison of MnO/Mn3O4, Mn3O4/MnO2, and pure Mn3O4 samples, MnO is found to play an important role in forming lattice − expanded spinel structure during the activation process.