Abstract: After the suggestion of “rocking chair rechargeable lithium battery” concept by Armand M at 1972, fundamental research on Li-ion batteries has passed 43 years. Deep and comprehensive understandings on materials, electrochemical reaction mechanism, thermodynamics and kinetics of lithium storage, structure evolution, surface and interface reactions, safety and mechanical properties have been achieved continuously, which promote the development of Li-ion batteries and lead to its commercialization. Currently,demandings on improving the performances and extending to broad applications are still very strong. Therefore, it is expected that basic research will be more helpful to provide better solutions, have more precise understandings on the relationship between properties and performances as well as the failure mechanism during fabrication and service, in addition to identify the effects of all creative strategies based on reliable scientific analysis. Moreover, the basic research on Li-ion batteries also enrich the knowledge of solid state electrochemistry, solid state ionics, energy materials, energy physics and nanoscience. As the last paper in this series, scientific problems, new tendency, difficulties, directions and tools for the fundamental research on lithium ion batteries are summarized briefly.

Key words: lithium-ion batteries, fundamental research