A High Rate 1.2V Aqueous Sodium-ion Battery Based on All NASICON Structured NaTi2(PO4)3 and Na3V2(PO4)3

In this work, a new aqueous rechargeable Na-ion battery is developed based on all NASICON structured electrodes in which NaTi2(PO4)3 serves as the anode, Na3V2(PO4)3 serves as the cathode, and aqueous Na2SO4 solution serves as the electrolyte. Such a combination of cathode-anode can fulfil the theoretical working window of aqueous electrolyte, thus give rise to a high cell voltage surpassing most of the previous aqueous Na-ion batteries. The developed NaTi2(PO4)3/Na3V2(PO4)3 aqueous full cell demonstrates a flat discharge plateau at 1.2 V and can well maintain its performance at high current rates. Even at a current density of 10 A g−1, the battery discharge capacity can still reach 58 mAh g−1. Together with a high voltage, this cell configuration enables a high energy density of 29 Wh kg−1 at a power density of 5145 W kg−1. The NaTi2(PO4)3/Na3V2(PO4)3 system can be a promising low cost alternative for the current aqueous secondary batteries especially in terms of the high voltage and high power application. By controlling the cut-off voltage and adjusting the mass ratio of cathode to anode, we explored the different electrochemical performances of the aqueous full cell and identify which side of the electrode dominantly affects the cell decay at the case of full utilizing one electrode material. This investigation may present useful insight to researchers working on both aqueous batteries and NASICON-based materials.