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Electric vehicle batteries could get big boost with new polymer coating

Electric vehicle batteries could get big boost with new polymer coating
Berkeley Lab researchers demonstrated that the HOS-PFM coating significantly prevents aluminum-based electrodes from degrading during battery cycling while delivering high battery capacity over 300 cycles. From left: Scanning electron microscope images of aluminum on a copper bilayer device before battery cycling (Figure A) and after (Figure B). Figure C shows a copper tri-layer device with HOS-PFM coating after battery cycling. Credit: Nature Energy (2023). DOI: 10.1038/s41560-022-01176-6

Scientists at Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a conductive polymer coating—called HOS-PFM—that could enable longer lasting, more powerful lithium-ion batteries for electric vehicles.

"The advance opens up a new approach to developing EV batteries that are more affordable and easy to manufacture," said Gao Liu, a senior scientist in Berkeley Lab's Energy Technologies Area.

The HOS-PFM coating conducts both electrons and ions at the same time. This ensures battery stability and high charge/discharge rates while enhancing . The coating also shows promise as a battery adhesive that could extend the lifetime of a lithium-ion battery from an average of 10 years to about 15 years, Liu added.

To demonstrate HOS-PFM's superior conductive and , Liu and his team coated aluminum and with HOS-PFM, and tested their performance in a lithium-ion battery setup.

Silicon and aluminum are promising for lithium-ion batteries because of their potentially high energy storage capacity and lightweight profiles. But these cheap and abundant materials quickly wear down after multiple charge/discharge cycles.

The HOS-PFM conductive binder is made of a nontoxic polymer that transforms at the atomic level in response to heat. Before heating: At room temperature (20 degrees Celsius), alkyl end-chains (black squiggly lines) on the PFM polymer chain limit the movement of lithium ions (red circles). After heating: When heated to about 450 degrees Celsius (842 degrees Fahrenheit), the alkyl end-chains melt away, creating vacant “sticky” sites (blue squiggly lines) that “grab” onto silicon or aluminum materials at the atomic level. PFM's polymer chains then self-assemble into spaghetti-like strands called “hierarchically ordered structures” or HOS. Like an atomic expressway, the HOS-PFM strands allow lithium ions to hitch a ride with electrons (blue circles). These lithium ions and electrons move in synchronicity along the aligned conductive polymer chains. Credit: Jenny Nuss/Berkeley Lab

During experiments at the Advanced Light Source and the Molecular Foundry, the researchers demonstrated that the HOS-PFM coating significantly prevents silicon- and aluminum-based electrodes from degrading during battery cycling while delivering high battery capacity over 300 cycles, a performance rate that's on par with today's state-of-the-art electrodes.

The results are impressive, Liu said, because silicon-based lithium-ion cells typically last for a limited number of charge/discharge cycles and calendar life. The researchers recently described these findings in the journal Nature Energy.

The HOS-PFM coating could allow the use of electrodes containing as much as 80% silicon. Such high silicon content could increase the energy density of by at least 30%, Liu said. And because silicon is cheaper than graphite, the standard material for electrodes today, cheaper batteries could significantly increase the availability of entry-level electric vehicles, he added.

The team next plans to work with companies to scale up HOS-PFM for mass manufacturing.

More information: Formation of hierarchically ordered structures in conductive polymers to enhance the performances of lithium-ion batteries, Nature Energy (2023). DOI: 10.1038/s41560-022-01176-6

Journal information: Nature Energy
Citation: Electric vehicle batteries could get big boost with new polymer coating (2023, March 7) retrieved 27 February 2024 from https://techxplore.com/news/2023-03-electric-vehicle-batteries-big-boost.html
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