The Battery Analytical Investigation (BAI) Research Group, led by Dr. Bai, is part of the Department of Energy, Environmental and Chemical Engineering, in the McKelvey School of Engineering, at Washington University in St. Louis. Our group aims to obtain precision understandings of the performance-limiting mechanisms in current and emerging batteries, by combining visualized electroanalytical methods, physics-based mathematical modeling, molecular dynamics simulations, and big-data-driven diagnosis. The purpose of this methodology is to gain fundamental insights and quantitative guidance for the rational design of not only the materials but also the electrodes and the systems toward practical applications.