One of the key challenges facing any battery chemistry is energy density. How does one increase energy density without compromising on safety? While this is important for all batteries in general, this is even more important for micro batteries that are to power critical sensors and implanted device. Needless to say, these batteries need to be safe – from energetic transformation events as well as from toxicity point of view. This is where the use of Solid Polymer Electrolyte comes in handy.
Typical way in which people fabricate solid polymer electrolyte to be use in Lithium batteries has been through radical initiation aided by thermal or UV radiation. While this approach provides films with sufficient quality for 2D structures, it falls short when you start employing this for 3D architectures. The coverage of electrolyte of the entirety of 3D structure is needed to utilize the electrochemically active electrode surface and thus full benefit of 3D structure is not realized with traditional methods.
This is where in-situ methods come in. Method that has been identified and reported by Muhammad E Abdelhamid et al involves the use of electrochemical polymerization. Benefits of this approach is multi fold: a) Since electropolymerization happens where electron conducting substrate is present, it ensures utilization of electrode surface by forcing ion conducting surface right there. b) The fact that the polymeric layer that is coated is insulting, the film growth is self limiting. c) Further control of thickness and morphology is obtained through potential and current control d) Avoids the addition of initiators and e) Simplifies battery fabrication process.
The team carried this out on both planar and finely controlled 10 micron diameter, 100 micron pillars and characterized the film for conductivity and compositional properties. They have shared the article that they published in Journal of Electrochemical Society through Open Access. You can learn more here..