Electric vehicle adoption faces hurdles, and one of the most significant is performance degradation in cold weather. Slow charging speeds and reduced range during winter months are well-documented frustrations. Now, researchers at the University of Michigan have engineered a potential solution using modifications to the battery manufacturing process.
Published in the journal Joule, their study demonstrates a method to achieve significantly faster charging at low temperatures (down to -10°C / 14°F) without compromising the battery’s energy density – the key factor determining driving range.
Standard lithium-ion batteries rely on the movement of lithium ions through a liquid electrolyte between the anode and cathode. Low temperatures impede this ionic movement, slowing down both discharge (power delivery) and charge rates. While thicker electrodes have increased overall capacity for longer range, they exacerbate the problem of slow ion diffusion, particularly in the cold.
The U-M team, led by Associate Professor Neil Dasgupta, developed a synergistic approach:
– Laser-Ablated 3D Structures: Previously, the team improved room-temperature charging by using lasers to create micro-channels (around 40 microns) within the graphite anode. These channels act as highways, facilitating faster lithium-ion transport deep into the thick electrode structure.
– Artificial Solid-Electrolyte Interphase (SEI): The critical bottleneck for cold charging was identified as the native SEI layer – a chemical layer that forms where the electrode meets the electrolyte. This layer becomes highly resistive at low temperatures, hindering ion transfer and promoting unwanted lithium plating (metallic lithium depositing on the surface), which damages the battery and reduces capacity. To overcome this, the team applied an ultra-thin (approx. 20 nm) glassy coating of lithium borate-carbonate. This artificial interface allows efficient ion transport even when cold, preventing plating.
Combining the 3D structured anodes with the nanocoating yielded remarkable results. The modified battery cells demonstrated:
– 500% faster charging at -10°C compared to baseline cells.
– Excellent capacity retention: 97% capacity maintained after 100 fast-charge cycles at low temperatures.
“We envision this approach as something that EV battery manufacturers could adopt without major changes to existing factories,” stated Dasgupta. Manoj Jangid, a co-author, added that preventing plating is key to maintaining energy capacity during fast charging.
This research directly confronts consumer hesitancy highlighted by recent surveys showing decreased likelihood to purchase EVs, partly due to winter performance concerns. The widely reported issues during the January 2024 cold snap underscore the need for solutions like this.
With follow-on funding aimed at factory-ready processes and commercialization efforts underway via Arbor Battery Innovations (which has licensed the channel technology), this U-M innovation represents a significant step towards making EVs practical and reliable in all climates.
