The rapid change of modern life and industry in the recent decades has witnessed the revolutionary development of electrochemical energy storage technologies, such as batteries and capacitors. For example, batteries evolved from heavy and bulky lead-acid ones that stores very little energy to light Li-ion batteries that could power up an entire vehicle. However, recently, further development of electrochemical energy storage has come to a halt and encountered a number of grand challenges, such as a lack of energy density, shortage of supply of key elements, and safety issues. Such stagnant development is because of a lack of understanding of critical chemical processes that are responsible for these key problems. This direction focuses on the design and application of advanced spectroscopic approaches to resolve the critical chemical processes, such as intercalation/conversion mechanism, phase change/structure transformation, kinetic processes, and surface phenomena. Such methodology will be applied for a wide range of energy storage applications battery/capacitor types. The ultimate goal is to bring up scientific solutions that resolve the current critical changes in the field energy storage.