Charging an electric vehicle fast without degrading the battery has been one of the harder problems in battery research. A team at Adelaide University says it has a way through it.

Six minutes. That is how long it took their new battery cell to reach 85 percent charge, while delivering an energy density of 240.4 watt-hours per kilogram.

The result comes from a team led by Professor Shi-Zhang Qiao, an ARC Industry Laureate Fellow in the University’s School of Chemical Engineering, working alongside researchers from Imperial College London.

Why fast charging has been hard to crack

The issue with existing high-capacity batteries, silicon-anode and lithium-anode types, is that speed comes at a cost. Capacity fades quickly, and fast charging generates heat that accelerates that degradation and raises safety concerns.

“Current models also increase heat generation during fast charging, which can exacerbate battery degradation and safety risks,” Professor Qiao said. “Until now, achieving more than 90 per cent charge within 10 minutes without sacrificing energy density and cycle life has been a formidable challenge.”

Standard approaches involve reworking the electrolyte — the medium ions travel through inside the cell. But changes to the electrolyte affect the whole system and tend to compromise ionic conductivity elsewhere.

What this approach does instead

Rather than modifying the electrolyte throughout, Qiao’s team targeted only the electrode surface. The method uses sulfur vacancies as catalytic sites that attract specific anions to the battery interface during charging, promoting the formation of a compact, lithium fluoride-rich protective layer (the solid electrolyte interphase) with fast lithium-ion transport pathways built into it.

“The catalytic sites on the electrode surface attract anions to the battery interface and promote the formation of a robust inorganic protective layer, which is critical for fast charging and long-term stability,” Professor Qiao said. “Unlike traditional electrolyte engineering, which often affects the entire electrolyte system, this strategy regulates reactions only at the interface, allowing fast charging without sacrificing ionic conductivity.”

The silicon anode achieved an average coulombic efficiency — how much charge put in can be drawn back out — of approximately 99.94 percent. At 10 minutes, the cells reached 91.4 percent.

How it held up over time

After 500 consecutive six-minute charge cycles, the cells retained around 76 percent of their original capacity.

“Our test cell exhibited excellent performance, achieving about 76 percent capacity retention after 500, six-minute cycles,” Professor Qiao said in a press release. “The cells also exhibited excellent stability at 10 minutes of charging. The discovery could help enable electric vehicles that charge in minutes without sacrificing battery life or energy density.”

The team’s next step is scaling the technology and testing it under real operating conditions. Their findings are published in Nature Energy.