Diatomite-Based Hybrid Electrolyte for Improving Reversibility of Cathode/Anode Interface Reaction in Zn-MnO2 Batteries

Abstract

The cyclic stability of aqueous zinc-manganese batteries (ZMBs) is greatly restricted by the side reaction of the anode and the irreversibility of the cathode. In this work, a solid-liquid hybrid electrolyte mixing by traditional ZnSO₄-based electrolyte and diatomite (denoted as Dtm) is proposed that exhibits good compatibility and reversibility in both the anode interface and the cathode interface. The abundant hydroxyl groups at the anode interface disturb the hydrogen bond network of water molecule, which weakens the corrosion of the active water to Zn anode. Moreover, the negatively charged surface of diatomite is able to regulate the electric field at the anode interface to promote the uniform deposition of Zn ion as well as inhibit the formation of Zn hydroxyl sulfate (ZHS) at the anode interface. As a result, Zn||Zn symmetric battery with Dtm achieves a stable cycling for 2500 h at 1 mA cm⁻²/1 mAh cm⁻², while Zn||MnO₂ battery can achieve a stable cycle time of 500 cycles at current densities of 0.2 and 0.5 A g⁻¹ with capacities of 228 and 177.6 mAh g⁻¹, respectively. The Dtm provides new ideas for electrolyte screening for high-performance aqueous ZMBs.