Developing Plasmonic Imaging Technique to Understand Battery Solid Electrolyte Interface Formation and Li Nucleation in-Situ

Abstract

During the operation of lithium-ion battery (LIB), a solid electrolyte interface (SEI) layer forms on the anode electrode materials due to side reactions with the electrolyte solvent and salt. It is essential to the performance of LIBs and it decides the initial capacity loss, self-discharge characterizstics, cycle life and safety. Therefore to understand the SEI formation is extremely important for battery research. Currently, most of characterization methods of SEI are based on electron microscope, although powerful, it is difficulty to directly map the SEI formation in-situ. We have developed a novel plasmonic imaging technique to image the local SEI formation and measure the electrochemical reaction of the anode electrodes. Unlike conventional electrochemistry that measures the electrical current from entire electrode, the plasmonic-based electrochemical microscope (PECM) technique is based on sensitive imaging of surface plasmonic signal caused by electrochemical reaction, which is measured optically, thus allowing for fast and non-invasive imaging of electrode processes. PECM can image localized chemical reactions on the electrode surface ins-situ, this information will be extremely important for us to understand SEI formation and electrochemical reaction on the anode electrode. The electrochemical reaction will always be accompanied by a conversion of the chemical species between oxidized and reduced states, and plasmonic imaging is extremely sensitive to the species generated (or consumed) on electrode materials. Therefore, the PECM has great potential to characterize the local electrochemical reactions and energy storage process.