A bio-inspired membrane of interfacial engineering in the cathode in aqueous magnesium-ion batteries

Limited by the high de-solvation energy barrier of hydrated Mg²⁺ and undesired interfacial water decomposition behavior, aqueous magnesium ion batteries normally suffer from sluggish ion transfer kinetics and drastic cathode dissolution. To overcome these obstacles, inspired by the amphiphilic structure of cell membranes, a MnO₂/carbon-based cathode composed of hydrophobic poly(3,4-ethylene-dioxythiophene) (PEDOT) and hydrophilic α-MnO₂ substrate was successfully constructed. In combination with experimental and theoretical calculations, the PEDOT layer can efficaciously enhance the conductivity for the overall electrode, reduce the de-solvation energy barrier of hydrated Mg²⁺, and inhibit the cathode dissolution, thereby boosting the performance of composite electrodes. Therefore, the as-prepared composite electrode demonstrates superior rate performance (58.4 mAh g⁻¹, 3 A g⁻¹) and enhanced long-term cycle stability (85.92 mAh g⁻¹ after 1000 cycles, 2 A g⁻¹) which is superior to the pristine α-MnO₂ cathode. Based on the bio-inspired design concept, this work will provide an innovative direction for the development of aqueous magnesium-ion batteries.