An improved N-N dimethylacetamide-based non-flammable molecular crowding electrolyte using NaOTf for cobalt-based prussian blue//hard carbon aqueous solution battery.

Aqueous sodium-ion batteries (ASIBs) are promising for large-scale electrical energy storage (LSEES) applications due to their cost and safety advantages. However, the low voltage stabilization window of water (∼1.23 V) and the lack of cathode with high specific capacity and long cycle life have limited their development. Cobalt-based Prussian blue analogues (NaCoPBAs) have the advantage of high theoretical specific capacity but short cycle life. Recently, the molecular crowding electrolyte (MCE) strategy has been proposed to improve the electrolyte voltage stability window (ESW) of electrolytes, in this work, we report an improved xMC (x: ratio, MC: molecular crowding agent) electrolyte that uses N-N dimethylacetamide (DMAC) as the molecular crowding agent and NaOTf as the advanced salt with an ESW of 2.65 V and excellent nonflammability. The side reactions of the NaCoPBA//Hard Carbon (HC) full-cell active material are improved with the aid of the electrolyte. Capacity retention of 75 % after 600 cycles with excellent cycling stability. These results demonstrate that this advanced MCE strategy can be utilized for practical applications designed for safety, high specific capacity and long cycle (ASIB).