A team of scientists has found a way to make use of an unusual material in next-generation batteries: Wood. The team from Brown University has developed a tree-derived material to be used in solid-state batteries, which are safer and less environmentally damaging than current batteries.
Current generation lithium-ion batteries, like those used in phones, computers, and electronic vehicles, use volatile liquids as electrolytes. These electrolytes conduct lithium ions between the positive and negative electrodes of a battery. Liquid electrolytes do this job well, but they are toxic and can be dangerous. If the battery experiences a short circuit, for example, the liquid can combust and the battery can catch fire. This isn’t usually a problem in everyday use, but it has led to the recall of some batteries which have been incorrectly manufactured.
To make batteries safer, researchers are developing solid-state batteries, in which a solid material is used as an electrolyte instead. A solid, non-flammable material would be safer to use and potentially less environmentally damaging to produce. Most of the current research into solid electrolytes has involved ceramics, which conduct ions very well but which are brittle and can easily crack or break.
The Brown team has developed a material to be used as a solid electrolyte which is composed of a combination of copper and polymer tubes that are derived from wood and are called cellulose nanofibrils. The polymer material the researchers developed is extremely thin and flexible, like a sheet of paper, which makes it easier to use in manufacturing. Yet its ion conductivity is as good as thicker, more brittle materials like ceramics.
“The lithium ions move in this organic solid electrolyte via mechanisms that we typically found in inorganic ceramics, enabling the record high ion conductivity,” said co-author Yue Qi, a professor at Brown’s School of Engineering, in a statement. “Using materials nature provides will reduce the overall impact of battery manufacture to our environment.”
The researchers say they hope this development will help make solid-state batteries commonly available to improve safety in consumer electronics.
The research is published in the journal Nature.
