Enabling Sodium Compensation, Stable CEI Formation and Fast-Charging Using Thiocarbamate Additive in NVP Cathodes.

To overcome the instability of sodium-ion cathode materials due to sodium losses and an unstable cathode electrolyte interface, the cathode additive method is an efficient approach; however, finding a cost-effective additive with a low decomposition potential remains a challenge. This work identifies a sodium salt of thiocarbamate as an appropriate sodium compensating reagent. The thiocarbamate salt was found to effectively decompose into an amorphous N, S-rich CEI at low voltage, simultaneously compensating for the sodium losses during cycling. When introduced as an additive to Na3V2(PO4)3 cathode, an addition of 10 wt.% extends the discharge capacity, charging behavior, and stability of the cathode. In the full cells, the use of the additive increases the energy density from 72.32 to 131.43 Wh kg-1, indicating great prospects of thiocarbamate functionality in revitalizing sodium-ion batteries for practical purposes.