World's first! China achieves major breakthrough in sodium‑ion batteries, completely blocking thermal runaway

Breakthrough with a polymerizable non‑flammable electrolyte

Researchers at the Institute of Physics, Chinese Academy of Sciences (中国科学院物理研究所), together with Zhongke Haina (中科海钠) and led by Hu Yongsheng (胡勇胜), have reportedly developed a polymerizable non‑flammable electrolyte (PNE) that prevents thermal runaway in ampere‑hour‑level sodium‑ion cells. IT Home (IT之家) and a Nature Energy paper titled "Thermal runaway‑free ampere‑hour‑level Na‑ion battery via polymerizable non‑flammable electrolyte" report that the team achieved complete suppression of thermal runaway in 3.5 Ah steel‑cased cylindrical cells — no smoke, no fire, no explosion — even when exposed to 300°C or subjected to a nail‑penetration test.

Technically, the group built a dual‑salt system using NaBF4 as the primary salt and NaPF6 as an auxiliary interfacial regulator to solve hard‑carbon anode compatibility. The electrolyte uses triethyl phosphate (TEP) as a non‑flammable base that undergoes rapid thermally triggered polymerization at high temperature to form a solid barrier layer. That layer isolates mechanical and chemical cross‑talk between anode and cathode and, the authors say, halts the cascade reactions that cause thermal runaway.

Performance, industrial prospects and geopolitical context

Importantly, the advance reportedly comes without sacrificing performance: the cells maintain a wide operating temperature range (‑40°C to 60°C), remain stable above 4.3 V, and a high‑energy pouch prototype reached about 211 Wh/kg (cell basis) while still surviving penetration testing. It has been reported that the materials used are mature industrial products, which the authors argue gives the approach strong potential for rapid scaling and commercialization.

Why does this matter to Western readers? Sodium‑ion chemistry uses abundant, low‑cost sodium rather than lithium, and improved safety at ampere‑hour scale could make these cells attractive for grid storage and lower‑cost electric vehicles. The breakthrough arrives against a backdrop of intense global competition over battery supply chains and growing Chinese emphasis on domestic alternatives amid export controls and technology restrictions. Reportedly, commercialization hurdles remain, but this paper marks a significant step toward safer, scalable sodium‑ion batteries.