Wearable electronics often use lithium ion batteries, but what happens if they’re twisted or broken?

Breaking a battery can lead to all sorts of problems, including the leakage of flammable, toxic, or corrosive gases or liquids.

A new thin, flexible lithium ion battery has self-healing properties that make it a safer choice for wearable technologies.

A new family of lithium ion batteries that can overcome accidents – and heal themselves – was developed by a team from Fudan University in Shanghai, the Samsung Advanced Institute of Technology in South Korea, and the Samsung R&D Institute in China. The team was led by Yonggang Wang and Huisheng Peng.

The electrodes in these self-healing batteries consist of layers of parallel carbon nanotubes, and between the layers, the scientists embedded the necessary lithium compounds in nanoparticle form (LiMN(2)O(4) for one and LiTi(2)(PO(4))(3) for the other. Compared to conventional lithium ion batteries, the lithium compounds cannot leak from the electrodes, either while in use or after a break. The thin layer of electrodes is fixed on a substrate of self-healing polymer. Between these electrodes is a novel, solvent-free electrolyte made from a cellulose-based gel with an aqueous lithium sulfate solution embedded in it. This serves as a separation layer between the electrodes.

If the battery breaks, the broken ends need only be pressed together for a few seconds for them to self-heal. The parallel arrangement of the nanotubes allows them to come together better than the layers of disordered carbon nanotubes.