Short-time and ultrasensitive electroanalytical technique for electrode active materials used in secondary batteries

摘要

In this article, a short-time and ultrasensitive electrochemical approach capable of detecting subtle phase changes during the charge-discharge process is introduced. It is attained through the use of a Si microparticle electrode specially prepared using the electrophoretic deposition (EPD) method. The features of the electrode are that it is binder-free and the active material is sparsely deposited onto the electrode. Despite the scan rate being 5 to 60 times faster than the usual scan rates, the cyclic voltammograms recorded at the binder-free Si microparticle electrode in the 83.3-16.7 mol% 1-ethyl-3-methylimidazolium bis(fluorosulfonyeamide -lithium bis (fluorosulfonyl)amide ionic liquid electrolyte indicate several redox waves related to the lithiation reactions with phase transition, although it is difficult to see similar waves when using common Si composite electrodes. Codeposition of both a Si active material and acetylene black onto the current collector using the EPD method significantly improves the sensitivity and performance of the electrode. Applying this electrode to operando scanning electron microscopy visually enables a deeper understanding of the impact of the morphology variation of the Si materials on the electrode performance within a short time.