Selective ion transport in assembled graphene oxide-modified separator and the novel intra-series architecture for improved aqueous batteries

Aqueous batteries, as one of the most promising candidates in large-scale energy storage, have attracted comprehensive attention owing to their high safety and low cost. Nevertheless, their poor lives are mainly caused by undesired side reactions and carrier transport due to the high solvent power and high proton activity of water. Herein, a strategy based on the separator design is developed to enhance the cycling stability of aqueous batteries. In this way, an assembled graphene oxide (GO) film is introduced to modify glass fiber separator, which can only allow alkali metal ions to pass through with the intercept of multivalent cations. Based on the design, the dissolution and destruction of sodium Prussian blue (PB-Na) are suppressed for achieving the long-life aqueous sodium-ion batteries (SIBs), providing a high capacity retention of 78.76% after 10,000 cycles at a current density of 2.0 A/g. Furthermore, the assembled GO film also enables a novel intra-series architecture with the combined mechanism of bipolar plate capacitor and battery for providing the extra capacity of electric double layer capacitor (EDLC). Independent from the optimization of electrode and electrolyte, the strategy based on the separator design would provide a new perspective for improving the performance of electrochemical energy storage system.