A new lithium-ion battery design developed by researchers in China may represent a major leap forward in battery safety. Their innovation significantly reduces the risk of thermal runaway—a dangerous chain reaction that can cause batteries to overheat, catch fire, or even explode.
Why Thermal Runaway Happens
Traditional lithium-ion batteries can reach temperatures exceeding 500 °C when damaged, overcharged, or affected by manufacturing defects. These events cause negatively charged ions (anions) to break their bonds with lithium, releasing large amounts of heat. Because these batteries are used in everything from EVs to laptops and power tools, mitigating that risk is critical.
A New Electrolyte Strategy
The research team discovered that ion association within the electrolyte plays a key role in how thermal runaway begins. By adjusting the electrolyte’s composition, they were able to delay the onset of this reaction by about 94 °C—a huge safety improvement.
Their approach uses a “solvent-relay strategy” that:
- Encourages stable SEI (solid electrolyte interphase) formation at normal operating temperatures.
- Triggers dissociation only at higher temperatures, preventing uncontrolled reactions.
- Uses lithium bis(fluorosulfonyl)imide to stabilize ion bonds and suppress anion decomposition.
Real-World Safety Testing
To validate the design, the team performed nail penetration tests on 1.1 Ah pouch cells. The results were striking:
- New electrolyte: temperature rise of just 3.5 °C
- Conventional electrolyte: temperature rise of 555.2 °C
The cells also maintained strong performance, operating at 4.5 V and delivering a cycle life of over 4,000 hours with around 82% capacity retention after 1,000 cycles.
A Safer Future for Lithium-Ion
This solvent-relay strategy could pave the way for safer lithium-ion batteries without compromising energy density or longevity. If adopted commercially, it could have far-reaching implications for electric vehicles, consumer electronics, and energy storage systems.
“This study elucidates the critical influence of ion association on thermal runaway and establishes an effective strategy to achieve prolonged cycle life, high cut-off voltage, and enhanced safety,” the authors note in their paper.
Reference: Yue Sun et al, “Designing safe and long-life lithium-ion batteries via a solvent-relay strategy,” Nature Energy (2025). DOI: 10.1038/s41560-025-01888-5.
