Soft X-ray emission spectroscopy finds plenty of room in exploring lithium-ion batteries

A wide range of advanced characterization tools has been exploited for energy issues. Soft X-ray emission spectroscopy (SXES) equipped with electron microscopy as an emerging analysis tool has made its debut in energy storage recently. The emergence of SXES provides powerful opportunities to explain the energy storage mechanisms, especially in the field of silicon-based anode for lithium-ion batteries. Herein, we summarize the SXES principles, development process and the unique advantages of SXES as well as coupling with other techniques. We further put forward our reasonable outlook for the development and application of SXES that will serve widely in materials science. IMPACT STATEMENT This review pioneers a themed application of the emerging soft X-ray emission spectroscopy, herein mechanistic insight into lithium ion batteries.