The work of the team is described in a recent paper, Physical–chemical hybrid transiency: A fully transient li-ion battery based on insoluble active materials, published in the Journal of Polymer Science, Part B: Polymer Physics. The team refers to the process as “physical-chemical hybrid transiency”. Basically, the self-deconstructing lithium-ion battery can maintain a potential of up to 2.5 volts (that’s enough to power a basic function calculator) and then once submerged in water the soluble components will dissolve within approximately 30 minutes.
The team created the transient battery using eight layers, including a cathode and an anode, and layers of a poly-vinyl alcohol (PVA) based polymer to form a small battery cell that is one millimeter thick, five millimeters long and six millimeters wide. When the battery is submerged within water, the polymer casing begins to swell and dissolve away. Although the battery doesn’t completely disappear, the nanoparticles themselves do not degrade, however the electrodes will break during the dissolution process.
“Unlike conventional electronics thatare designed to last for extensive periods of time, a key and unique attribute of transient electronics is to operate over a typically short and well-defined period, and undergo fast and, ideally, complete self-deconstruction and vanish when transiency is triggered,”
The transient battery was subject to electrochemical testing and impedance measurements where the internal resistance of the unit measured at “frequencies between 1.0E5 and 0.1 Hz and a potential difference (DV) of 10 mV” (Journal of Polymer Science, Part B: Polymer Physics, 2016). The team determined that the active materials used in their process are most suitable for secondary cell batteries. However, batteries constructed as primary cell can withstand initial and periodic charging and discharging but it will result in reduced tranciency due to chemical reactions of the elements. The research further indicates that it is possible to apply this process to a larger scale battery however the time for dissolution of materials is dependent on the size of the battery (i.e. the larger the battery, the longer the dissolution process).
This new transient battery could serve a variety of functions including military operations and hardware security applications, as well as dissoluble medical implants or even environmental sensors. We believe this new technology also shows potential to one day help reduce electronic waste and improve the conditions in places like Agbogbloshie, a massive landfill of electronic materials, devices, and equipment are illegally disposed of.
