Manganese dioxide (MnO2 ) is an attractive cathode material for aqueous zinc batteries (AZBs) owing to its environmental benignity, low cost, high operating voltage, and high theoretical capacity. However, the severe dissolution of Mn2+ leads to rapid capacity decay. Herein, a self-assembled layer of amino-propyl phosphonic acid (AEPA) on the MnO2 surface, which significantly improves its cycle performance is successfully modified. Specifically, AEPA can be firmly attached to MnO2 through a strong chemical bond, forming a hydrophobic, and uniform organic coating layer with a few nanometers thickness. This coating layer can significantly inhibit the dissolution of Mn2+ by avoiding the direct contact between the electrolyte and cathode, thus enhancing the structural integrity and redox reversibility of MnO2 . As a result, the MnO2 @AEPA cathode achieves a high reversible capacity of 223 mAh g-1 at 0.5 A g-1 and a high capacity retention of 97% after 1700 cycles at 1 A g-1 . This work provides new insights in developing stable Mn-based cathodes for aqueous batteries.
Keywords: amino-propyl phosphonic acid; aqueous zinc batteries; manganese dioxide; self-assembled layers; surface coating.
© 2024 Wiley-VCH GmbH.