Choi, Yong SeokPharr, MattKang, Chan SoonSon, Seoung-BumKim, Seul ChamKim, Kee-BumRoh, HyunchulLee, Se-HeeOh, Kyu HwanVlassak, Joost2015-09-022014Choi, Yong Seok, Matt Pharr, Chan Soon Kang, Seoung-Bum Son, Seul Cham Kim, Kee-Bum Kim, Hyunchul Roh, Se-Hee Lee, Kyu Hwan Oh, and Joost J. Vlassak. 2014. “Microstructural Evolution Induced by Micro-Cracking During Fast Lithiation of Single-Crystalline Silicon.” Journal of Power Sources 265 (November): 160–165. doi:10.1016/j.jpowsour.2014.04.124.0378-7753http://nrs.harvard.edu/urn-3:HUL.InstRepos:22068311We report observations of microstructural changes in {100} and {110} oriented silicon wafers during initial lithiation under relatively high current densities. Evolution of the microstructure during lithiation was found to depend on the crystallographic orientation of the silicon wafers. In {110} silicon wafers, the phase boundary between silicon and LixSi remained flat and parallel to the surface. In contrast, lithiation of the {100} oriented substrate resulted in a complex vein-like microstructure of LixSi in a crystalline silicon matrix. A simple calculation demonstrates that the formation of such structures is energetically unfavorable in the absence of defects due to the large hydrostatic stresses that develop. However, TEM observations revealed micro-cracks in the {100} silicon wafer, which can create fast diffusion paths for lithium and contribute to the formation of a complex vein-like LixSi network. This defect-induced microstructure can significantly affect the subsequent delithiation and following cycles, resulting in degradation of the electrode.en-USLithium-ion batteriesSiliconMicrostructureNon-uniform lithiationMicro-crackJournal Article2015-08-28YS Choi, M Pharr, CS Kang, SB Son, SC Kim, KB Kim, H Roh, SH Lee, KH Oh, JJ Vlassak2015-09-0210.1016/j.jpowsour.2014.04.124