Comparative study on ternary spinel cathode Zn–Mn–O microspheres for aqueous rechargeable zinc-ion batteries

We demonstrate the cation ratio-controlled synthesis of ZnMn₂O₄ and Zn_1.67Mn_1.33O₄ aggregated microspheres. The carbonate precursor was synthesized by a solvothermal reaction, and then completely converted to oxide by calcination at 600 °C with a controlled cationic ratio. The prepared ternary oxide has a nanoparticle-aggregated morphology and uniform size distribution. The electrochemical properties were investigated by cyclic voltammetry and constant current charge-discharge measurements. The Zn_1.67Mn_1.33O₄ electrode reveals better performance for Zn²⁺ storage than the other, delivering 175 mA h g⁻¹ after 40 cycles. After the electrochemical test, ex situ analysis was conducted to identify the Zn²⁺ storage mechanisms. From these results, we confirm that the Zn_1.67Mn_1.33O₄ cathode is a promising Zn²⁺ storage material for environmental friendly aqueous rechargeable Zn-ion batteries.