Enhanced Performance of Sn4P3 Electrode Cycled in Ionic Liquid Electrolyte at Intermediate Temperature as Na‐Ion Battery Anode

Charge-discharge performances of Sn4P3 anodes for Na‐ion battery were evaluated in an ionic liquid electrolyte using N‐methyl‐N‐propylpyrrolidinium bis(fluorosulfonyl)amide at intermediate temperatures of 60 and 90 oC. At these temperatures, the anode showed extra capacities based on the full sodiation of Sn in a potential range below 0.2 V vs. Na+/Na because its slow kinetics was improved by elevating operation temperature. Under the current density of 0.1 A g-1 (0.08 C), the Sn4P3 anode at 60 oC exhibited a large capacity of 750 mA h g-1 at the 120th cycle and high Coulombic efficiencies above 99% after the 5th cycle. On the other hand, the efficiency degraded at 90 oC by the electrolyte decomposition. At 60 oC, the anode attained an excellent rate performance with capacity of 250 mA h g-1 even at 3 A g-1 (2.65 C). These results demonstrated the promising operation at intermediate temperature at around 60 oC for Sn4P3 anode in ionic liquid electrolyte.