New technique incorporates lithium-bearing polymer electrolytes into microbatteries
New technique incorporates lithium-bearing polymer electrolytes into microbatteries lead image
Microelectronic devices and microelectromechanical systems have numerous applications, such as wearable electronics, robotics and biomedical fields. These miniscule electronics need equally tiny batteries, which present scientists with the challenge of developing lightweight designs with adequate energy storage and areal capacity.
Lithium ion batteries hold promise for their theoretically high energy densities and light weight, but modifications to electrochemical cells in microbatteries can compromise them.
Researchers Gao and Tenhaeff present a new way to incorporate lithium-bearing polymer electrolyte materials into microbatteries. They use a method called initiated chemical vapor deposition (iCVD) to produce thin film polyelectrolytes.
To maintain stability of the film during ion exchange process, the authors crosslinked them with ethylene glycol diacrylate. The authors proved the ion exchange process does not alter the surface chemistry and structure of graphite, and the electrochemical properties of the material are maintained.
“One important benefit in using ion exchanged polyelectrolytes is that the films are single ion conductors with near unity transference number since the polyelectrolyte backbone is immobile. This eliminates transport limitations due to salt concentration polarization of conventional salt-loaded polymer electrolytes, where the lithium salt anion also has high mobility, often with higher diffusivities than Lithium cation,” author Wyatt Tenhaeff said.
iCVD is conformal, highly controllable in terms of thickness and composition, and can deposit intractable, insoluble thin films in a single step at low temperature. iCVD also results in defect-free thin film polyelectrolytes with continuous, smooth surfaces.
The authors believe the next step is to improve conductivity through continued innovation in thin film polymer compositions.
Source: “Synthesis and characterization of thin film polyelectrolytes for solid-state lithium microbatteries,” by Yifan Gao and Wyatt E. Tenhaeff, Journal of Vacuum Science & Technology B (2019). The article can be accessed at https://doi.org/10.1116/1.5109436 .
