Comparison of NaNi1/3Fe1/3Mn1/3O2 and Na4Fe3(PO4)2(P2O7) cathode sodium-ion battery behavior under overcharging induced thermal runaway

It is expected that the safety characteristics of sodium-ion batteries are higher than that of lithium-ion batteries, but the response of sodium-ion batteries with different material systems under thermal runaway is still lacking in-depth analysis. In this study, the thermal runaway characteristics of NaNi1/3Fe1/3Mn1/3O2 and Na4Fe3(PO4)2(P2O7) cathode pouch sodium-ion batteries are compared. First, thermal runaway experiments analyze the electro-thermal–mechanical-gas response of the two kinds of sodium-ion batteries. Based on this, the sodium plating and gas generation process under overcharge conditions are analyzed using coin batteries and in-situ cells coupled with optical microscopy. By combining the macro and micro characteristics at different stages of thermal runaway, this study elucidates the thermal runaway characteristics and corresponding causes of the two kinds of cathode material sodium-ion batteries. The results provide a foundation for subsequent research on the materials of sodium-ion batteries and methods for monitoring thermal runaway.