Electrolyte Coatings for 3D Microbatteries
New battery architectures which are miniturized for micro applications while optimized for both energy and power densities
Typical 2D lithium-ion batteries consist of three superimposed layers: anode, electrolyte-separator, and cathode. As these layers are reduced to the thin-film regime, batteries must cover areas more than 1cm2 for sufficient energy capacity. Minimizing area by growing thicker electrodes results in lowered power-density from sluggish ion-transport. To reach the micro-scale in battery area as well, we must leave the 2D-film model and create 3D batteries from anode or cathode post-arrays. These high aspect ratio electrodes require the development of a conformal coating which can perform all of the duties of a solid electrolyte. The film must be pinhole-free, electrically insulating, and ionically conducting.
The project is being approached collaboratively from many angles, with our group working on plasma-phase deposition of polyethyleneoxide-like electrolyte films, which are insulating and can be intercalated with lithium ions. An instrument for plasma deposition was designed and constructed in-house. Currently, reaction parameters for control over film-thickness and electrochemistry are being investigated, and the resulting films are in analysis for thier chemical composition (XPS), ion-affinity (impedance spectroscopy), and conformallity at the nano-scale (SEM and AFM).