Reza Montazami and co-workers, Iowa State University, Ames, Iowa, USA, have fabricated a fully transient lithium ion battery that dissolves in water in half an hour.

The battery was made of polyvinyl alcohol (PVA) composites, carbon black, a cellulose-based electrolyte spacer, and typical electrode materials. The large number of hydroxyl groups in PVA allow the polymer to swell by over 150 % in water. Sucrose was added to the PVA layer to enhance water penetration and decrease the time it takes for the PVA layer to fully swell. Swelling of the PVA layer fragmented the rest of the electrode, leading to its deconstruction. After the initial fragmentation, the electrode materials quickly break down into milli/micrometer size particles.

The battery has a potential of 2.53 V, which is double that of previously reported transient electrodes. The battery was used to power a basic calculator with a threshold voltage around 1 V for around 15 minutes.

Transient electronics operate over a typically short and well-defined period and undergo fast and, ideally, complete self-deconstruction and vanish when transiency is triggered. They have a wide range of potential applications including those in healthcare, biomedical devices, environmental sensing/monitoring, green electronics, military and homeland security.

• Physical-chemical hybrid transiency: A fully transient li-ion battery based on insoluble active materials,
  Yuanfen Chen, Reihaneh Jamshidi, Kathryn White, Simge Çınar, Emma Gallegos, Nastaran Hashemi, Reza Montazami,
  J. Polym. Sci., Part B: Polym. Phys. 2016.
  DOI: 10.1002/polb.24113