Better Batteries With Carbon NanotubesMay 31 2020
Lithium batteries have been around for decades. It powers all our modern gadgetry, from cellphones to cars. These batteries are made from lithium, which is a highly abundant, low-cost metal. Despite its ubiquity, lithium batteries have one specific disadvantage – they lose charge capacity rather quickly.
Typical lithium batteries last for 300-500 charges before performance deteriorates. At that point, the battery would lose about 20% of its charge capacity. This loss of capacity continues until the battery practically becomes useless.
The degradation is caused by a natural process. As lithium batteries charge and discharge, dendrites form on the negative terminal (anode). As they grow, these tentacle-like dendrites penetrate the electrolyte layer and reach the positive terminal (cathode), damaging the battery permanently.
This problem is what Rice University chemist James Tour aimed to solve. His lab team used carbon nanotubes to coat the anode of a lithium battery. The team then subjected this battery and a control battery, which did not have the nanotube film, to 580 charge cycles. Afterwards, they compared microscope images of the two batteries.
The researchers found out that the carbon nanotube film effectively stopped the growth of dendrites in the experimental battery. They further reported that the battery retained 99.8% of its Coulombic efficiency, which is a measure of how well electrons flow.
In practical terms, this means that a nanotube-coated lithium battery lasts much longer than ordinary ones. This technology can then pave the way for longer-lasting, and even safer, batteries.