Electrodeposition of Conformal Ultrathin Functional Polymer Interphases

Sub-micron interphases and coatings determine surface and interfacial properties of materials, which in turn are often dominant factors in defining their performance in applications and devices. Especially in electrochemistry, interfacial processes including charge and mass transfer depend on the nanometric environment around the electrode surface, which can be tailored with functional interphases. Polymer chemistry offers a large toolbox of molecular functionalities to create coatings and interphases with desired properties, but conformal deposition of uniform ultrathin films on micro- and nanostructured electrodes in batteries, fuel cells, and electrocatalytic systems remains elusive. Hence, new coating methods are required to achieve ultrathin uniform interphases that allow for tuning and tailoring of interfacial electrochemical processes in application-relevant electrodes. Here, we present a strategy to achieve conformal ultrathin coatings of functional polymers on porous and conductive materials with arbitrarily complex architecture through a novel electrodeposition paradigm. Our fabrication method separates the controlled deposition chemistry from the polymer properties through rational molecular design, making it agnostic and applicable to many polymer compositions and functionalities. We demonstrate how deposition and molecular parameters determine the interphase properties, including molecular permeability and thickness from 10s to 100s of nanometers, which in turn enables tunability over interfacial properties under electrochemical conditions such as modulation of the double layer and activation/passivation of molecular species. We envision our process to enable novel electrochemical material, composite, and device architectures with advanced performance characteristics, and serve as tailored model systems in mechanistic studies from electrocatalysis to energy storage.