Probing microstructure evolution of Si/C anode for Li-ion batteries via synchrotron transmission X-ray tomographic microscopy

Abstract

Holding great potentials as an excellent anode for Li-ion batteries, Si has received enormous attention, and its degradation theory has been enriched extensively based on various characterizations over time. To provide a more comprehensive diagnosis for current Si/C anodes, ex situ phase-contrast synchrotron transmission X-ray tomographic microscopy (TXTM) is applied to study a Si/C electrode sampled at representative cycling numbers. Through a series of data segmentations and identifications, three-dimensional Si/C electrodes are described in details with both global and localized structure features, which are rationally linked to the electrochemical characteristics as well as the previous discoveries. This successfully establishes an updated electrode-level failure process for common Si/C anodes where the electrode degradation is primarily initiated by the nonstop Si-phase pulverization with continually-expanded LixSi/electrolyte interface, and manifested as the internal void space expansion and the ever-growing electrode thickness. Bearing this in mind, multiple complementary and synergistic solutions towards limiting the intrinsic Si rupture and electrolyte decomposition should be developed to ensure a high-performance Si-based anode over long-term cycling for Li-ion battery in the near future.