Polymer coating could enable longer lasting, more powerful lithium-ion batteries for electric vehicles

Scientists at Lawrence Berkeley National Laboratory have developed a conductive polymer coating – called HOS-PFM – that could prove significant for the future of lithium-ion battery use in EVs.

Gao Liu, a senior scientist in Berkeley Lab’s Energy Technologies Area explains: ‘The HOS-PFM coating conducts both electrons and ions at the same time. This ensures battery stability and high charge/discharge rates while enhancing battery life. 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.’

Silicon and aluminium both have potentially high energy storage capacity and lightweight profiles which makes them of interest as electrode materials for lithium-ion batteries but the downside is that they wear down quickly after multiple charging cycles.

This is exactly why the research team used those materials, coated with with HOS-PFM to showcase the polymer’s conductive and adhesive properties in a lithium-ion battery setup. 

Experiments demonstrated that the HOS-PFM coating significantly prevented the silicon and aluminum-based electrodes from degrading during battery cycling, while delivering high battery capacity over 300 cycles – a performance rate on par with current state-of-the-art electrodes. And of course silicon and aluminium are both inexpensive and abundant.

Liu said: ‘The advance opens up a new approach to developing EV batteries that are more affordable and easy to manufacture. 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 lithium-ion batteries by at least 30%. 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.’ 

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

Lithium batteries are a hot topic at the moment with recent research into lithium-air batteries attracting attention. There is also a growing effort to curtail the not inconsiderable implications of throwing away 9m tonnes of lithium-ion batteries a year.