Comparison study of electrochemical and thermal stability of Na 3 V 2 ( PO 4 ) 3 in different electrolytes under room and elevated temperature

The compatibility and reactivity between electrode materials and electrolytes is important to design safe batteries. As cathode material with guaranteed performance, the knowledge of thermal stability of the reactivity between Na3V2(PO4)3 (NVP) and carbonate-based electrolyte are still limited. Therefore, the electrochemical performance of NVP as a positive electrode material for sodium-ion batteries was tested at room temperature using coin cells with six conventional electrolytes. The results show that the charge-discharge performance of cells with different electrolytes can be ranked as cells with NaPF6 ≈ NaTFSI > NaClO4 based electrolytes. Moreover, the thermal reactivity of six kinds of electrolytes, charged NVP and their mixture was studied using accelerating rate calorimetry under elevated temperature. Thermal behaviors of NVP electrode system at elevated temperature under the condition of abundant electrolyte or electrode were clearly identified. Among the six electrolytes, the thermal stability of NVP in NaTFSI-based electrolyte was the best when more electrolyte was used, while that NaClO4 based electrolyte the best when less electrolyte was used. These results provide a basis for sodium-ion batteries using NVP as a cathode from the perspective of safety.