Lithium ions do not travel alone inside a charging battery. They carry solvent molecules with them, and that movement can leave an electrode short of the liquid it needs. 

University of Maryland researchers have now redesigned an electrolyte to tackle this overlooked obstacle to faster charging. The team tested the chemistry in a four-amp-hour pouch cell, reaching 80 percent charge in 12.8 minutes and 90 percent in 14.7 minutes. The research offers a route toward shorter EV charging stops by changing battery chemistry.

Led by researcher Chang-Xin Zhao in Distinguished University Professor Chunsheng Wang’s laboratory, the work addresses a practical challenge: bringing charging times closer to the minutes drivers spend filling a gasoline tank. The researchers now aim to reduce that wait further, to around 10 minutes.

During charging, lithium ions move from a battery’s positive electrode to its negative electrode through the electrolyte. Along the way, they pick up solvent molecules and pull them in the same direction.

At slower charging speeds, the solvent can flow back into the porous positive electrode, replenishing what has moved away. When charging accelerates, however, that return flow struggles to keep pace. The electrode begins to dry out, and charging slows markedly.

The phenomenon, known as electro-osmotic drag, was already familiar to researchers studying fuel cells. Its role in lithium-ion batteries had been overlooked until the Maryland-led study.

Previous approaches to faster charging have focused on altering electrode structures. Those changes can reduce the energy a battery holds, creating a trade-off the team wanted to avoid.

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