Toward a low-cost high-voltage sodium aqueous rechargeable battery

Recent discovery of high-concentration electrolyte systems has opened a new avenue toward the high-voltage, safe, and low-cost aqueous rechargeable batteries. However, the need for generally high-cost organic solutes in the high-concentration electrolyte has become another major obstacle. Herein, we revisited all the commonly used low-cost solutes for high-concentration system and discovered that the use of NaClO 4 solute effectively results in a wide electrochemical stability window by suppressing water decomposition and induces stable solid-electrolyte interphase (SEI) layer formation without involving the reduction of salt anions. The SEI layer, composed of Na 2 CO 3 and Na O compounds including NaOH, guarantees the excellent electrochemical storage stability of the full-cell composed of Na 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ) cathode and NaTi 2 (PO 4 ) 3 anode for the extended period of time.…