A New Tree-Based Material Gives Solid State Batteries a Safety Boost

Trees make everything better. Even EV batteries.
Chris Young

Trees provide the air we breathe, and now, in an interesting turn of events, they might also help to power our electronics. A team of researchers from Brown University and the University of Maryland developed a new material that can be used in solid-state batteries to improve the safety and power of traditional batteries by replacing the liquids typically used in lithium-ion cells, a press statement reveals.

The material in question is a kind of cellulose nanofibril, which takes the form of polymer nanotubes derived from wood. The researchers found that it could be combined with copper to produce a paper-thin material that has an ion conductivity between 10 and 100 times better than other polymer ion conductors.

"By incorporating copper with one-dimensional cellulose nanofibrils, we demonstrated that the normally ion-insulating cellulose offers a speedier lithium-ion transport within the polymer chains," said Liangbing Hu, a professor in the University of Maryland’s Department of Materials Science and Engineering. "In fact, we found this ion conductor achieved a record high ionic conductivity among all solid polymer electrolytes."

Reducing the global environmental impact of electronics

Though liquid electrolytes in lithium-ion batteries generally work well, they have their own problems too. Aside from the fact that they are made using toxic, flammable chemicals, they can also develop dendrites — tiny filaments of lithium metal — at high currents, leading to short circuits. Solid-state batteries don't have these problems, and their production also doesn't rely on the mining of lithium-ion, which is bad for the environment.

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The new solid electrolyte has a similar ion conductivity to other solid electrolytes made out of ceramics, and the fact that it is thin and flexible means it is not prone to cracking under stress like its ceramic alternative. "The lithium ions move in this organic solid electrolyte via mechanisms that we typically found in inorganic ceramics, enabling the record high ion conductivity," Qi said. "Using materials nature provides will reduce the overall impact of battery manufacture to our environment."

The scientists hope their work will help to enable the mass production of solid-state batteries, a technology that has the potential to improve the sustainability of battery production at the same time as giving it a massive power boost due to its higher energy density. Crucially, cellulose nanofibril is a renewable natural fiber, meaning that the production of the new electrolyte wouldn't damage the natural ecosystems from which it is derived. 

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