Built-in extinguishers can prevent battery fires and explosions

Researchers have designed a working prototype of a lithium metal battery equipped with a built-in fire extinguisher, which is activated if the battery overheats.

Lithium metal batteries are currently in limited use but have huge potential because they can store ten times as much energy as lithium-ion batteries. They deliver high energy density, which means they can store large amounts of energy relative to their size. This makes them ideal for electric vehicles, portable electronics and plenty of other energy-hungry devices.

Risk of fires and explosions

However, there is a problem. These types of batteries use lightweight lithium metal anodes and high-voltage nickel-rich oxide cathodes, a setup that can produce flammable gases. If these gases build up in a battery, they can cause fires or explosions.

To tackle this, Ying Zhang and colleagues at the Institute of Chemistry, Chinese Academy of Sciences, incorporated a flame-retardant polymer into the cathode of their prototype lithium metal battery.

Published in Proceedings of the National Academy of Sciences, the researchers exposed the prototype battery and a standard lithium metal battery to gradually increasing temperatures, starting at 50 °C. When temperatures exceeded 100°C, both batteries began to overheat.

However, in the prototype, the special polymer started to break down and release chemicals (flame-inhibiting radicals) that acted like mini fire extinguishers. Specifically, they suppressed reductive reactions at the anode that are responsible for generating flammable gases.

When temperatures rose beyond 120 °C, the standard battery overheated to 1,000 °C within 13 minutes and burst into flames. Meanwhile, under the same experimental conditions, the prototype with the flame-retardant polymer reached a peak temperature of 220 °C and did not catch fire or explode.

“This smart gas management strategy enhances both thermal safety and electrochemical stability, offering a transformative pathway to fire-safe Li metal batteries for advanced energy storage applications,” explained the researchers in their paper.

Safer batteries

If this fire-suppressing technology proves successful on a large scale, it could be a game changer for safer batteries in everything from portable electronics and medical devices to grid storage and electric vehicles. By reducing the risk of fires, this breakthrough could also encourage more people to switch their gas-guzzling cars for electric ones, as safety concerns are one reason some people remain hesitant.

Additionally, with a few modifications, the flame-retardant material can be incorporated into batteries using existing battery production methods, which could help speed up their rollout and acceptance.

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