Industry and other government agencies are advancing battery, fuel cell, and electrolyzer technology to reduce costs and increase specific power. However, NASA's unique missions with extreme conditions and difficulty in replacing batteries require even greater specific power improvements in conjunction with long life and performance at extremely high or low temperatures. Predictive models, incorporating the thermodynamics and electrochemistry that dictates device performance and degradation, are needed to accelerate development and insertion of these systems. To provide this capability, CFDRC and our collaborator Dr. Partha Mukherjee, TAMU, will develop and validate detailed models that link chemical composition and elementary reaction steps with the properties and reactions of electrochemical system constituents. The proposed electrochemical models will be based on fundamental chemical and electrochemical properties of the materials, as opposed to empirical fits of observed properties for a specific battery electrode material and electrolyte mixture or fuel cell catalyst, support, and electrolyte combination. A property database and software library will be used and extended, allowing application of the developed models in performance simulators of NASA preference. The ability of the developed models to incorporate detailed thermodynamics and electrochemical kinetics of degradation processes will be demonstrated during Phase I, with extension to additional materials and validation during Phase II. The resulting models will significantly reduce the need for iterative, trial-and-error tests of new materials to accelerate development and increase confidence in projected device lifetimes.