Facile fabrication of mesoporous Ag-doped γ-MnO2 nanowires with rich oxygen defects for boosting performance of aqueous Zn-ion batteries

Abstract

In recent years, the aqueous zinc-ion batteries (AZIBs) have attracted a remarkable attention due to their low cost, abundance, low toxicity and high safety. MnO2 is considered a potential electrode for AZIBs owing to its high theoretical capacity and abundance. However, MnO2 suffers a challenging issue of poor cyclability. Herein, mesoporous Ag-doped γ-MnO2 nanowires were fabricated for the first time by a facile room temperature co-precipitation method under the assistance of Ag+ and investigated electrochemically as cathode for AZIBs. The as-obtained sample electrode delivers a remarkable discharge specific capacity of 978 mAh g-1 at the 65th cycle at a current rate of 0.1 C to be steady at 804 mAh g-1 after 150 cycles and exhibits an excellent rate capability at high C-rate due to the surface-controlled capacitive process of the electrochemical reaction, which is attributed to the unique structure of Ag-doped γ-MnO2 nanowires with rich oxygen defects and crystal water for more active sites and stable structure. This work offers aspiration for the future cathode material engineering as AZIBs.