Lithium metal batteries have far greater energy storage capacity than current lithium-ion batteries, offering up to ten times the energy. They are ideal for electric vehicles, medical devices, and portable electronics. However, their great potential comes with serious risks — they can overheat and explode. The problem stems from the battery components: the lithium metal anode and high-voltage nickel-rich oxide cathode produce flammable gases. When these gases accumulate, even slight overheating can trigger fire or explosion.
Now, researchers at the Institute of Chemistry of the Chinese Academy of Sciences have developed a lithium metal battery with a built-in flame retardant. Its prototype contains a polymer that releases flame-retardant chemicals when the temperature rises, acting like a miniature fire extinguisher. The researchers embedded the flame-retardant polymer directly into the battery cathode. The material remains stable at normal operating temperatures. When the battery temperature exceeds 100°C, the polymer decomposes and releases free radicals that inhibit chemical reactions at the anode — reactions that typically generate flammable gases.
To test the system, the research team compared the prototype with a standard lithium metal battery under identical conditions, gradually increasing the temperature starting from 50°C. At 100°C, both batteries began to overheat, but only the prototype activated its built-in flame suppression mechanism. The difference became clear above 120°C: the standard battery reached 1000°C and caught fire within 13 minutes, while the prototype reached a peak of 220°C without catching fire or exploding.
In the paper, the researchers explained that this intelligent gas management strategy enhances thermal safety and electrochemical stability, providing a transformative pathway for fireproof lithium metal batteries in advanced energy storage applications.
The addition of this flame-retardant polymer may change perceptions of lithium metal batteries, especially in the electric vehicle sector. Safety is one of the main concerns for consumers switching from gasoline cars to electric vehicles. If this technology is successfully promoted, it could alleviate these concerns.
The battery industry can also benefit in manufacturing. The researchers noted that only minor modifications to existing production methods are needed to incorporate the fire-extinguishing material. This means companies can adopt the upgrade without overhauling their current processes. This compatibility can accelerate real-world testing and commercial promotion.
Although lithium metal batteries currently have limited use, this breakthrough may help push them toward mainstream adoption. Safety risks have long restricted their application. The study, published in the Proceedings of the National Academy of Sciences, demonstrates a possible way forward. Safer batteries could pave the way for more powerful energy storage across various fields without the risk of fire. This prototype combines high energy density with built-in safety, offering a vision of the future where performance does not require sacrificing peace of mind.
