After an introductory reminder of safety concerns pertaining to early rechargeable battery technologies, this review discusses current understandings and challenges of advanced sodium-ion batteries. Sodium-ion technology is now being marketed by industrial promoters who are advocating its workable capacity, as well as its use of readily accessible and cheaper key cell components. Often claimed to be safer than lithium-ion cells, currently only limited scientifically sound safety assessments of sodium-ion cells have been performed. However, the predicted sodium-ion development roadmap reveals that significant variants of sodium-ion batteries have entered or will potentially enter the market soon. With recent experiences of lithium-ion battery failures, sodium-ion battery safety management will constitute a key aspect of successful market penetration. As such, this review discusses the safety issues of sodium-ion batteries, presenting a twofold innovative perspective: (i) in terms of comparison with the parent lithium-ion technology making use of the same working principle and similar flammable non-aqueous solvent basis, and (ii) anticipating the arrival of innovative sub-chemistries at least partially inspired from successive generations of lithium-ion cells. The authors hope that the analysis provided will assist concerned stakeholders in the quest for safe marketing of sodium-ion batteries.

After an introductory reminder of safety concerns pertaining to early rechargeable battery technologies, this review discusses current understandings and challenges of sodium-ion batteries. Sodium-ion technology is now being marketed by industrial promoters who are advocating its workable capacity, use of readily accessible and cheaper key cell components. Often claimed to be safer than lithium-ion cells, currently only limited scientific-sound safety assessment of sodium-ion cells has been performed. However, the predicted sodium-ion development roadmap reveals that significant variants of sodium-ion batteries will potentially enter the market in the near future. With recent experiences of lithium-ion battery failures, sodium-ion battery safety management will constitute a key aspect of successful market penetration. As such this review discusses the safety issues of sodium-ion batteries presenting a twofold innovative perspective: i) in terms of comparison with the parent lithium-ion technology making use of the same working principle and similar flammable non-aqueous solvent basis and ii) anticipating the arrival of innovative sub-chemistries at least partially inspired from successive generations of lithium-ion cells. The authors do hope that the analysis provided will assist the concerned stakeholders in the quest for safe marketing of sodium-ion batteries.

Sodium-ion batteries are emerging as supplementary technology to lithium-ion batteries. This study focuses on investigating the thermal stability of Na3V2(PO4)2F3 (NVPF) || hard carbon (HC) sodium-ion cells through the lens of Solid Electrolyte Interphase. Differential Scanning Calorimetry demonstrated a clear increase in SEI stability formed with improved electrolyte formulations (NaFSI and additives). At cell level, Accelerating Rate Calorimetric tests were performed on pristine versus aged batteries. Ramp heating analysis revealed consistent thermal behavior, with SEI degradation initiating near 155 °C and thermal runaway (TR) triggering around 210 °C in both pristine and aged batteries. However, Heat Wait Search analysis on aged cells exhibited less severe TR compared to pristine batteries. The higher onset temperature observed in aged batteries was attributed to enhanced thermal stability of the re-formed SEI, while the reduced thermal severity was proven to be unlinked to the lower energy density.