This course introduces students to the fundamentals of energy storage and provides a broad understanding and appreciation of various energy storage systems (ESSs). Through the course study, the students master the basic scientific principles that underpin the operation of different ESSs and the evaluation methods, gain knowledge regarding the basic energy conversion/storage process and critical technologies in different ESSs, and understand the latest research development and industrial application of different ESSs. In addition, the students need to understand the integration technology, management and application of different ESSs. The future development and concept of energy Internet will be finally introduced. Through the course study, the students are trained to have the capability of critically thinking and analyzing different ESSs.