Coral-Like Hierarchical Nanostructured ZnMn₂O₄/Mn₂O₃ Composites Synthesized by Zinc-Absent Method as a High-Performance Cathode Material for Aqueous Zinc-Ion Batteries

As one of the multivalent ion batteries, the zinc ion battery has the advantages of high-volume energy density and good safety. In this paper, coral-like and nanoparticle crosslinking hierarchical nanostructured ZnMn2O4/Mn2O3 composites were successfully synthesized as cathode materials for zinc ion batteries by a simple sol-gel combined with the zinc-absent method. ZnMn2O4/Mn2O3 composites with good properties were prepared when the zinc content was 10%. The prepared ZnMn2O4/Mn2O3 composites have the morphology of coral-like and nanoparticle crosslinking and uniform particle size distribution. Compared with pure ZnMn2O4 and Mn2O3, the composites show excellent electrochemical properties. Using 0.5 M Zn(CF3SO3)2-AN/H2O (8:2) as the electrolyte, the first discharge capacity of the material can reach 170.7 mAh·g−1 at 0.05 C. After 150 cycles, the discharge capacity remained 109 mAh·g−1. The kinetic characteristic of the electrode was studied by the galvanostatic intermittent titration technique, and the electrochemical reaction mechanism was studied by ex situ XRD. It was found that the two-phase recombination improved the diffusion rate of Zn2+. In the field of aqueous zinc ion batteries, an effective modification idea is provided for the research of spinel ZnMn2O4 cathode material with low specific capacity.