Research Objective and Approach, This research effort focuses on the application of thin, passive surface coatings to engineer the stability of nanoporous silicon materials and activate them as stable electrodes for electrochemical energy storage and conversion devices. Silicon combines earth abundance, low mass density, high achievable bulk conductivity, and easily manufactured nanoporous architectures making it ideal for such applications despite reactivity in electrochemical environments that renders it unusable for stable electrochemical devices. The approach of this research will be to apply gas-phase deposition techniques to coat thin films of stable materials including graphene, metal oxides, and metal nitrides, onto three-dimensional nanoporous silicon. This allows the silicon-electrolyte interface stability to be engineered while still preserving the controllable structure and surface area achieved with nanoporous silicon. Electrochemical stability and energy storage capability of these materials will be assessed using the development and testing of porous silicon-based high power electric double-layer capacitor devices. This research approach will then adopt a plants-to-power storage theme where silicon materials derived directly from plant matter or agricultural waste will be transformed into materials exhibiting stable electrochemical performance due to the application of controlled thin-film surface coatings.
Benefits to Society, If successful, the benefit of this research program will be the design of new materials with direct impact on grid-scale and portable energy systems. Transformation of abundant silicon-containing resources into energy devices enables low-cost, grid scale systems imperative to future energy sustainability. The use of processed natural resources to develop electrochemical solar cells, capacitors, and desalination systems collectively represent a sustained route toward basic resources of water and energy that will be transformative for low-income or third-world countries. Direct integration of silicon energy devices into excess silicon in photovoltaics, sensors, or electronics will enable more efficient electronics and portable technology in addition to the broader crosscutting societal impact of innovation in the surface engineering of silicon nanomaterials. Furthermore, the PI and Co-PI will participate and lead local and national outreach programs including the Vanderbilt Summer Academy, Vanderbilt students volunteering for science, and the Boy Scouts of America Engineering Explorers to engage K-12 students in order to strengthen and diversify a future STEM workforce.
