Engineers are looking to put lithium-ion batteries on a diet, as reducing their weight will improve the range and operating costs of electric vehicles (EVs). An opportunity to replace weighty and costly copper and aluminum components in these power sources has been explored by U.S. Oak Ridge National Laboratory (ORNL) researchers.

A carbon fiber-carbon nanotube polymer-based composite was developed and tested as an alternative to the weighty metals commonly used in battery current collectors. These alternative materials offer high thermal and electrical conductivities in addition to the requisite mechanical properties.

The aligned fibers work together with a thin film of carbon nanotubes to enhance directional and uniform current flow. Experiments conducted at medium-fast battery charging rates demonstrated that nodes fabricated with the novel current collector performed as well as or better than those equipped with standard copper foil. Lower charge resistance and enhanced rate capability were documented for the re-designed components compared with copper-based anodes.

The carbon polymer material described in the Journal of Energy Storage is also less susceptible to corrosion and can stretch more easily for roll-to-roll manufacturing of electrodes. Most importantly, the carbon-based current collectors weighed in at less than 1.5 mg/cm², offering a less hefty replacement for the commonly used copper foil tipping the scales at 8.7 mg/cm². This reduction in weight is also expected to improve gravimetric energy density.