Anion Receptor Weakens ClO4- Solvation for High-Temperature Sodium-Ion Batteries

Sodium-ion batteries (SIBs) with wide operating temperature are regarded as promising candidates for large-scale energy storage systems. However, SIBs operating under elevated temperature aggravate the electrolyte decomposition with unstable cathode-electrolyte interphase (CEI), causing a rapid capacity degradation. Herein, anion receptor tris(pentafluorophenyl)borane (TPFPB) is selected as electrolyte additive to construct robust NaF-rich CEI. The strong interactions between anion and TPFPB via the electron-deficient boron atoms weaken ClO4- solvation and promote the coordination capability between solvents and Na+ cations, demonstrating greatly improved oxidative stability. Na3V2(PO4)(3) cathode in TPFPB-containing electrolyte delivers long-term stability with a capacity retention of 86.9% after 100 cycles at a high cut-off voltage of 4.2 V (vs. Na+/Na) and a high temperature of 60 degrees C. Besides, TPFPB also works well with enhanced performance over a temperature range from -30 to 60 degrees C. This study proposes a prospective method by manipulating the solvation chemistry for constructing high-temperature rechargeable SIBs.

Automated summary

In this study, tris(pentafluorophenyl)borane was used as an electrolyte additive to build a stable NaF-rich cathode-electrolyte interphase (CEI) in sodium-ion batteries. The strong interactions between the anion and TPFPB improved the oxidative stability and long-term stability of Na3V2(PO4)3 cathode at high temperatures.