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

Abstract 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 NaTi 2 (PO 4 ) 3 nanocubes anode is engineered through a facile, low‐cost, and large‐scale hydrothermal approach. Na 0.44 MnO 2 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 NaTi 2 (PO 4 ) 3 nanocubes enables high stability and rate performance. Moreover, the adoption of deep eutectic electrolytes can minimize the Mn dissolution in the Na 0.44 MnO 2 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.