Construction of a robust cathode protection layer inspired by the wet adhesion behavior of mussels towards high-performance aqueous zinc-ion batteries†

Abstract

Constructing artificial layers is an effective strategy to enhance the cathode performance of aqueous zinc-ion batteries (AZIBs). However, inferior adhesion between the artificial layer and the cathode falls short of meeting the practical application requirements of the device. In nature, mussels demonstrate stable wet adhesion to various substrates owing to their secretion of dopamine species. Inspired by this unique mechanism, a unique polydopamine (PDA) layer was decorated onto MnO₂ nanorods via in situ chemical polymerization and a PDA-coated MnO₂ (PDMO) composite electrode was obtained. Theoretical computations and experimental analysis revealed that the PDA layer improved the conductivity of the electrode, restrained the adsorption behavior of the active H₂O molecules, and boosted the de-solvation process of hydrated Zn²⁺ owing to its robust adhesion property, abundant zincophilic groups, and engineered hydrophobicity. Therefore, the as-prepared PDMO cathode exhibited prominent electrochemical capabilities, such as a desirable rate performance (125 mA h g⁻¹ at 4 A g⁻¹) and long-term cycling stability (157 mA h g⁻¹ after 3500 cycles at 2 A g⁻¹), offering significant competitiveness with previously reported Mn-based cathodes. Meanwhile, the as-assembled PDMO‖Zn pouch cell successfully drove the electronic devices and exhibited enhanced cycling capability. This work integrates a bio-inspired design into battery system design and provides a bright direction towards AZIBs.