The availability of low-cost but intermittent renewable electricity (e.g., derived from solar and wind) underscores the grand challenge to store and dispatch energy so that it is available when and where it is needed. Redox-active materials promise the efficient transformation between electrical, chemical, and thermal energy, and are at the heart of carbon-neutral energy cycles. Understanding design rules that govern materials chemistry and architecture holds the key towards rationally optimizing technologies such as batteries, fuel cells, electrolyzers, and novel thermodynamic cycles. Electrochemical and chemical reactions involved in these technologies span diverse length and time scales, ranging from Ångströms to meters and from picoseconds to years. As such, establishing a unified, predictive framework has been a major challenge. The central question unifying our research is: “can we understand and engineer redox reactions at the levels of electrons, ions, molecules, particles and devices using a bottom-up approach?” Our approach integrates novel synthesis, fabrication, characterization, modeling and analytics to understand molecular pathways and interfacial structure, and to bridge fundamentals to energy storage and conversion technologies by establishing new design rules.