Researchers at China’s University of Hong Kong have taken a significant step towards safer lithium-ion batteries. They have altered the composition of the electrolyte in a prototype battery, and suppressed overheating after nail penetration. This progress bodes well for a class of batteries plagued by rare, but alarming lithium-ion battery fires.
Why Safe Lithium-Ion Batteries Are Critical
Lithium-ion batteries are everywhere we go in our world of batteries, on account of their high voltage and long lives. But we do need a way to achieve these benefits within a safe design. The current shortcoming is obstructing the roll out of electric vehicles, that could otherwise significantly reduce global warming over time.
However, and here’s the catch, the current generation of lithium-ion batteries may overheat when damaged, or if they are defective. The average battery in this class can dramatically overheat by a factor of 500°C / 950°F, under those circumstances.
When the Hong Kong scientists trialed their revolutionary electrolyte in the laboratory, something dramatic happened. When they conducted a nail penetration simulating battery damage, the temperature inside the battery increased by a mere 3.5°C / 38°F.
How the Scientists Made This Remarkable Improvement
The team from China’s University of Hong Kong discovered an ion association in electrolytes that lowered the temperature inside lithium-ion batteries. This is a technical term for a chemical reaction, whereby ions of opposite electric charge come together in solution to form a distinct chemical entity.
The scientists realized that this meant they could theoretically keep lithium-ion battery temperatures below thermal runaway criticality. They achieved a giant step towards safer lithium-ion batteries, when they replaced some of the solvent in the electrolyte with a different material.
Their novel solvent – which they call lithium bis(fluorosulfonyl)imide – only bonds with the existing solvent at high temperatures. Thus it does not appear to affect normal lithium-ion battery performance, while shutting the door firmly on thermal runaway!
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