Comparative safety analysis of current and next-generation battery technologies

The global transition to sustainable energy systems demands high-performance batteries, yet the inherent safety limitations of lithium-ion batteries (LIBs)—particularly thermal runaway driven by flammable liquid electrolytes—pose critical barriers to widespread adoption in safety-critical applications. This review conducts a comprehensive, evidence-based comparative safety assessment of three pivotal battery technologies: incumbent LIBs, emerging sodium-ion batteries (SIBs), and solid-state batteries (SSBs). We establish a detailed safety baseline for LIBs, examining failure mechanisms under thermal, electrical, and mechanical abuse conditions, including thermal runaway progression (T 1 , T 2 , T 3 ), gas evolution profiles, and cell-to-cell propagation dynamics. SIBs demonstrate significant safety improvements through higher thermal runaway initiation temperatures (220–260 °C vs. 170–220 °C for NMC LIBs), reduced heat release rates, lower hydrogen content in off-gases (30 % vs. 42 % for LFP), and transformative zero-volt transport capability. SSBs, particularly oxide-based variants, represent a paradigm shift by eliminating flammable liquid electrolytes, achieving exceptional thermal stability (T 2 > 600 °C), minimal gas evolution (