Polypyrrole-intercalation tuning lamellar structure of V2O5·nH2O boosts fast zinc-ion kinetics for aqueous zinc-ion battery

The layered structure of vanadium oxide is an ideal cathode material for aqueous rechargeable zinc-ion batteries (ARZIBs) owing to its tunable structures, high specific capacity and high energy density. It has been shown that the regulation of the layer spacing of the layered vanadium oxide can effectively improve the electrochemical performance of ARZIBs. Most of the literatures have adjusted the layer spacing by chemical pre-insertion of metal ions and the expanded layer spacing is very limited. However, other guests, like polymer, might play a critical role in tuning the lamellar structure of vanadium oxides showing fast Zn-ion kinetics for ARZIBs. Herein, a two-step synthesis is developed to insert the conductive polymer polypyrrole (PPy) into the vanadium oxide layers, resulting in a layer spacing up to 14.0 Å. Large interlayer spacing is beneficial to the rapid (de)intercalation of zinc ions, leading to greatly promote the electrochemical performance of V2O5·nH2O (VOH). The Zn//PPy/VOH battery has an advanced specific capacity up to 383 mAh·g−1 at 0.1 A g−1 and a steady cycle performance. This strategy of pre-insertion of conducting polymer into the host material provides a novel synthesis scheme for the use of vanadium oxide as cathode material for ARZIBs.