Tech Insights

Researchers Develop Conductive Polymer Coating to Extend EV Battery Life

March 31, 2023 by Shannon Cuthrell

Researchers from California’s Berkeley Lab unveil a new polymer coating to improve the performance and lifecycle of lithium-ion batteries for electric vehicles. 

New research out of the Lawrence Berkeley National Laboratory (Berkeley Lab) in California employs a conductive polymer coating to boost the lifecycle of lithium-ion batteries, the current industry standard used in most electric vehicles.


HOS-PFM coating in action at room temperature before heating (68 degrees Fahrenheit) and after heating at 842 degrees Fahrenheit. Image used courtesy of Jenny Nuss/Berkeley Lab


Dubbed “HOS-PFM,” the coating’s function of conducting electrons and ions simultaneously means the battery will remain stable even during high charge and discharge cycles. The coating acts as a battery adhesive capable of extending the lithium-ion battery lifecycle to 15 years, up from the current average of 10 years. 


Taken from a scanning electron microscope, images “A” and “B” show aluminum on a copper bilayer device before and after battery cycling. “C” adds the HOS-PFM coating to a tri-layer copper device, displaying its state after battery cycling. Image used courtesy of Nature Energy


How Does the Conductive Polymer Coating Work?

The study, led by Berkeley Lab’s Energy Technologies Area division with support from the U.S. Department of Energy (DOE), was published in a recent edition of Nature Energy. The abstract points out that conductive polymers have found new applications in energy storage and conversion devices. Conventional conductive polymers introduced organic functionalities to modify individual polymers’ properties, a change that comes with the drawback of limiting their scaled synthesis and applications. 

The researchers built on that conventional design with a conductive polymer with thermally processed “hierarchically ordered structures”—this is what the “HOS” refers to in HOS-PFM. The coating substantially improves charge transport properties and enables superior cycling performance with fuel cells. 

In testing the HOS-PFM on a lithium-ion battery setup at the DOE-funded Molecular Foundry and Advanced Light Source facilities, the researchers found the coating prevents degradation while delivering high capacity over 300 cycles, meeting the current performance of electrodes. 


Boosting Electric Vehicle Adoption

Berkeley Lab’s new coating technology could boost EV adoption, addressing consumers’ desires for longer-lasting battery materials. It would also help EV manufacturers better compete with traditional gas-powered cars. 


Berkeley Lab’s new coating technology could boost EV adoption. Image used courtesy of Pixabay

According to the National Renewable Energy Laboratory, electric cars must reliably perform for ten to 15 years in different climates and cycle levels to compete with conventional internal combustion engine vehicles. The federal government mandates EV manufacturers to provide an eight-year (100,000-mile) battery warranty. California’s standard extends for ten years (150,000 miles). So arises the demand for longer lasting-batteries that don’t sacrifice performance.

Cost is another benefit: Silicon and aluminum electrodes are cheap, abundant, and provide high energy storage capacity at a lower weight. Berkeley Lab’s research adds to those advantages, showing that conductive polymer coating shields the silicon and aluminum electrodes from degrading through 300 charging cycles. 

The research opens up opportunities to utilize electrodes containing up to 80% silicon, which would boost the energy density of lithium-ion batteries by 30% or more. Silicon is also cheaper than industry-standard graphite for electrodes.

The researchers plan to collaborate with companies to prepare the coating for mass manufacturing. Toyota Research Institute provided partial funding for the study, with additional support from the DOE’s Vehicle Technologies Office.