Battery Electrolyte Made From Wood Offers Better Conductivity
Scientists have used cellulose derived from wood as the basis for a solid electrolyte which is paper-thin and can bend and flex to absorb stress as the battery cycles, thus offering an alternative to liquid electrolytes used in current lithium batteries.
Photo Insert: The study is a stepping stone to battery technology that could help break the energy-density bottleneck and enable electric cars and planes to travel much farther without charging.
One shortcoming of the electrolytes used in lithium batteries is that they contain volatile liquids that carry a risk of fire if the device short circuits and can promote the formation of tentacle-like growths called dendrites that compromise performance, Nick Lavars reported for New Atlas.
Solid electrolytes, meanwhile, can be made from non-flammable materials, make the device less prone to dendrite formation, and might open up entirely new possibilities around battery architecture. One of these possibilities relates to the anode, one of the two electrodes, which in today's batteries is made from a mix of graphite and copper.
Some scientists see solid electrolytes as a key stepping stone to making batteries work with an anode made from pure lithium metal instead, which could help break the energy-density bottleneck and enable electric cars and planes to travel much farther without charging.
Many of the solid electrolytes developed so far have been made from ceramic materials, which are highly effective at conducting ions but don't stand up so well to stress during charging and discharging owing to their brittle nature.
Scientists from Brown University and the University of Maryland sought an alternative to this and used cellulose nanofibrils found in wood as their starting point. These wood-derived polymer tubes were combined with copper to form a solid ion conductor boasting conductivity similar to ceramics and between 10 and 100 times better than other polymer ion conductors.
According to the team, this is because the addition of copper creates space in between the cellulose polymer chains for "ion superhighways" to form, enabling the lithium ions to travel with record efficiency.