Breakthrough in the research on the interface composition of the solid electrolyte of lithium batteries

　　Although lithium-ion batteries have become the mainstream of energy storage today, the molecular and atomic basic sciences of their charging and discharging are still a mystery.

　　Although lithium-ion batteries have become the mainstream of energy storage today, the molecular and atomic basic sciences of their charging and discharging are still a mystery.

　　According to a study conducted by the Argonne National Laboratory of the US Department of Energy in "NatureCatalysis", the research team has achieved a breakthrough in the chemical composition of the solid-electrolyteinterphase (SEI) between the electrode and the liquid electrolyte. Dusan Strmcnik, a chemical engineer in the Materials Science Department (MSD) of Argonne National Laboratory, said this will help improve the team’s ability to predict battery life, which is crucial for electric vehicle manufacturers.

　　Scientists have been committed to cracking the SEI of lithium-ion batteries for a long time, but they only know that SEI is formed when the battery is charged, and a thin film of thousands of millimeters thick is produced on the graphite electrode. This film can protect the interface from harmful reactions and allow lithium Ions shuttle between the electrode and the electrolyte, so for lithium-ion batteries, a good SEI is a necessary condition. Strmcnik pointed out that battery efficiency and life depend on SEI quality. If scientists can find out its chemical properties and independent composition rules, SEI can improve battery efficiency.

　　Therefore, the Argonne National Laboratory, the University of Copenhagen in Denmark, the Technical University of Munich in Germany and the BMW Group formed an international research team, and successfully solved the common chemical substance lithium fluoride (lithiumfluoride) of lithium-ion battery SEI.

　　The results of experiments and calculations indicate that the electrochemical reaction of hydrogen fluoride (hydrogenfluoride) occurs during battery charging, which transforms the electrolyte into solid lithium fluoride and generates hydrogen gas. This type of reaction is highly dependent on electrode materials such as graphite, graphene, and metals, which proves the battery catalyst The importance of.

　　The team is also developing a new method for detecting the concentration of hydrogen fluoride. Since hydrogen fluoride is a harmful substance formed by moisture and lithium salt (LiPF6), this detection method plays a key role in SEI's future scientific research. Researcher NenadMarkovic said that the research will be tested in the BMW Battery R&D Center in the future. The next step of the research is to plan to design a new lithium-ion battery technology to open up another path for today's lithium-ion batteries.