Researchers Achieve 5X Faster EV Charging in Freezing Weather

The adverse effects of cold temperatures on electric-vehicle (EV) battery performance are well known. Current EV batteries store and release power through the movement of lithium ions back and forth between electrodes via a liquid electrolyte. Cold temperatures slow down this movement of ions, reducing both battery power as well as the charging rate.

However, a new technique offers a promising alternative that effectively addresses these limitations.

In the past, to extend range, automakers increased the thickness of the electrodes they use in battery cells. But these solutions have only made things worse by further limiting fast-charging capabilities and providing less power for a given battery weight.

Enabling high-energy-density lithium-ion batteries that can charge in less time would accelerate public acceptance of electric vehicles. “Charging an EV battery takes 30 to 40 minutes even for aggressive fast charging, and that time increases to over an hour in the winter. This is the pain point we want to address,” said Neil Dasgupta, University of Michigan associate professor of mechanical engineering and materials science and author of the study published in Joule.

Carving a New Path in Battery Electrode Manufacturing

A new strategy for manufacturing battery electrodes is said to enable charging in 10 minutes in temperatures as cold as −10°C. The strategy employs a modified manufacturing process for EV batteries, developed by University of Michigan scientists, that could enable high battery-powered range and fast charging in cold weather.

The research alters the battery’s structure and adjusts the chemical reactions that occur during charging. These modifications work to combat the thickening of the electrolyte liquid caused by cold weather, which slows down the movement of lithium ions and extends charging times.

 “We envision this approach as something that EV battery manufacturers could adopt without major changes to existing factories,” said Dasgupta.

Prof. Dasgupta and his team developed a strategy that integrates 3D electrode architectures with an artificial solid-electrolyte interphase (SEI) using atomic layer deposition of a solid electrolyte (Li₃BO₃-Li₂CO₃). These modifications enhanced both mass transport and interfacial kinetics under low temperatures and fast charging, increasing the accessible capacity of thick electrodes (>3 mAh/cm²).

Maintaining Capacity After 100 Fast Charges

The structure and coating demonstrated by the team prevented the formation of performance-hindering lithium plating on the battery’s electrodes. As a result, batteries with these modifications keep 97% of their capacity even after being fast-charged 100 times at very cold temperatures.

At a 6C rate and a temperature of −10°C, these integrated electrodes enabled a >500% increase in accessible capacity and >97% capacity retention after 100 cycles without Li plating.

Previously, Dasgupta’s team improved battery-charging capability by creating pathways — roughly 40 µm in size — in the anode, the electrode that receives lithium ions during charging. Drilling through the graphite by blasting it with lasers enabled the lithium ions to find places to lodge faster, even deep within the electrode, ensuring more uniform charging.

This sped up room-temperature charging significantly, but cold charging was still inefficient. The team identified the problem: the chemical layer that forms on the surface of the electrode from reacting with the electrolyte. Dasgupta compared this behavior to butter: You can get a knife through it whether it’s warm or cold, but it’s a lot harder when it’s cold. If you try to fast charge through that layer, lithium metal will build up on the anode like a traffic jam.

Material Dramatically Boosts Cold-Weather Charging

Scientists applied a thin layer of lithium borate-carbonate — approximately 20 nm thick — to the battery. This material proved instrumental in increasing charging efficiency by 500% in cold weather. These structural modifications not only accelerated ion flow, but also prevented detrimental side reactions, ensuring the battery performs optimally even in icy conditions.

The team applied for patent protection with the assistance of U-M Innovation Partnerships. Arbor Battery Innovations has licensed and is working to commercialize the technology. Dasgupta and the University of Michigan have a financial interest in Arbor Battery Innovations.

Follow-on work to develop factory-ready processes is funded by the Michigan Economic Development Corporation through the Michigan Translational Research and Commercialization (MTRAC) Advanced Transportation Innovation Hub.