Higher energy volumes can be stored in electromagnetic, chemical, and mechanical forms, while smaller units can be easily stored and used via EES devices (Venkatesan et al. 2022; Mitali et al. . Electrochemical energy conversion and storage (EECS) technologies have aroused worldwide interest as a consequence of the rising demands for renewable and clean energy. As a sustainable and clean technology, EECS has been among the most valuable options for meeting increasing energy requirements. . NLR is researching advanced electrochemical energy storage systems, including redox flow batteries and solid-state batteries. Electric vehicle applications require batteries with high energy density and fast-charging capabilities. . ostatic adsorption or Faradaic intercalation. Here the authors propose that the storage mechanism is a continuous transition between the two phenomena depending on the ext transition metal oxide lithium-ion batteries? Energy2, 16208 (2017). charge Q is stored. So the system converts the electric energy into the stored chemical energy in charging process. through the external circuit. . The chapter starts with an introduction of the general characteristics and requirements of electrochemical storage: the open circuit voltage, which depends on the state of charge; the two ageing effects, calendaric ageing and cycle life; and the use of balancing systems to compensate for these. .