A lithium-ion battery has been hacked to charge itself when it is flexed or compressed, a breakthrough that could lead to a class of small, portable electronics that stay charged without ever being plugged in.
To do it, researchers at the Georgia Institute of Technology removed the barrier that normally separates the two electrodes in a lithium-ion battery and replaced it with a nanotube film with piezoelectric properties.
Piezoelectric devices typically convert movement into electricity such as this electricity-generating backpack. In a totally separate second step, that electricity can then be converted into chemical energy, which is what happens when you charge a battery.
By placing the material between the battery electrodes, the mechanical energy is converted directly to chemical energy, completely bypassing the need to generate electricity at all.
“The device basically acts as a hybrid generator-battery unit, or in other words, a self-charging power cell,” Phys.org explains.
The hybrid battery was described in a recent issue of the journal Nano Letters.
To prove the concept, the team stuck one of their coin-size batteries on the bottom of a shoe. They found that walking could generate enough energy to charge the battery.
Next up for the team is scaling up the technology so that it can charge batteries with high a enough voltages to be useful for portable gadgets.