Synergistic effect of high concentration sodium bis(fluorosulfonyl)imide electrolyte and fluorinated ethylene carbonate enabling stability and high-rate performance of Na metal batteries

[Display omitted] •High concentration electrolyte exhibited superior thermal, electrochemical stability, Al corrosion inhibition.•The synergistic effect of high concentration electrolyte NaFSI/DME (2:1 wt ratio) and FEC additive could extend noticeable cycle life of batteries.•The cycling performances of Na3V2(PO4)3 cathodes at high-rate were dramatically improved in NaFSI/DME (2:1) FEC 3 wt%. Sodium metal anodes-based batteries have been widely attracted owing to their advantages like high specific capacity, abundant resources, de-alloying with copper. Herein, we demonstrate a high concentration electrolyte of NaFSI and DME (2:1 wt ratio) with FEC 3 wt% additive enabling a high-rate performance sodium metal batteries using Na3V2(PO4)3 cathode up to 400 cycles. The novel electrolyte system exhibits superior thermal, electrochemical stability, inhibits Al corrosion, and improves cycling performance. The Na3V2(PO4)3 cathodes could deliver an initial discharge capacity of 93.1 mAhg−1, capacity retention of 76.4 % after 400 cycles, and Coulombic efficiency is over 90% during cycling test.