Towards High-Performance Aqueous Sodium Ion Batteries: Constructing Hollow NaTi₂(PO₄)₃@C Nanocube Anode with Zn Metal-Induced Pre-Sodiation and Deep Eutectic Electrolyte

The aqueous rechargeable sodium-ion battery (ARSIB) is considered to be the most promising candidate for large-scale energy storage applications, due to its low cost, safety, and eco-friendliness. However, the poor cycle life and low energy density of ARSIB impede its practical applications. In this context, hollow NaTi₂(PO₄)₃ nanocubes anode is engineered through a facile, low-cost, and large-scale hydrothermal approach. Na_0.44MnO₂ cathode delivers a high capacity of 75.16 mAh g⁻¹ with the compensation of sodium ions by the zinc metal-induced pre-sodiation of the anode in a deep eutectic electrolyte. The well-designed structure in hollow carbon-coated NaTi₂(PO₄)₃ nanocubes enables high stability and rate performance. Moreover, the adoption of deep eutectic electrolytes can minimize the Mn dissolution in the Na_0.44MnO₂ cathode. When coupling the cathode and anode, the as-assembled ARSIB with a deep eutectic electrolyte exhibits an ultralong cycle life up to 3500 cycles (with capacity retention of 90%), an ultrahigh energy density of 50.0 Wh kg⁻¹, and superior rate capability (maximum power density of 1500 W kg⁻¹). This ARSIB represents an alternative promising candidate for large-scale electrochemical energy storage.