A Solid‒Liquid Synergy Strategy Enables High-Performance Pouch Sodium-Ion Batteries Over a Wide-Temperature Range of -30 °C To 60 °C

Abstract

Abstract:A “solid‒liquid synergy” strategy is first developed to design functional multicomponent electrolytes and successfully achieve extreme temperature performance of NaNi0.33Fe0.33Mn0.33O2 (NFM)/hard carbon (HC) sodium-ion batteries (SIBs) over a wide range from -30 °C to 60 °C. Unlike well-known multicomponent electrolytes, coupling sodium difluorophosphate (NaDFP) with tris(trimethylsilyl) phosphate (TMSP) or tris(trimethylsilyl) borate (TMSB) reasonably enhances the wide-temperature performance of pouch SIBs because of the optimized solvation structure and synergistically formed interfacial films. The cycling stability is considerably improved under room and cold conditions, the capacity retention after 350 cycles increases from 0% to 92%, and even stable cycling performance at 1 C (1 C = 900 mA) can be obtained at -10 °C. The discharge capacity at -30 °C and the capacity retention after storage at 60 °C are also greatly improved. Furthermore, the functional mechanisms of different NaDFP- and TM-based combinations under extreme temperature conditions are analyzed, and the results demonstrate that P-based (B-based) combinations are more suitable for high/low temperature requirements. In addition to the obtained functional electrolytes, this work provides new insight for designing functional multicomponent electrolytes.

Keywords: Keywords: Sodium-ion battery, functional electrolyte, extreme-temperature performance, electrolyte‒electrode interfaces, pouch cells.