TY - JOUR
T1 - Direct Visualization of the Solid Electrolyte Interphase and Its Effects on Silicon Electrochemical Performance
AU - Sina, Mahsa
AU - Alvarado, Judith
AU - Shobukawa, Hitoshi
AU - Alexander, Caleb
AU - Manichev, Viacheslav
AU - Feldman, Leonard
AU - Gustafsson, Torgny
AU - Stevenson, Keith J.
AU - Meng, Ying Shirley
N1 - Funding Information:
This research was supported by the Office of Vehicle Technologies, U.S. Department of Energy under Contract No. DE-AC02-05CH11231, Subcontract No. 7073923 under the Advanced Battery Materials Research (BMR) Program. The Rutgers HIM is supported by NSF grant DMR-1126468. M.S. and J.A. contributed equally to this work. M.S. acknowledges Rutgers IAMDN and UCSD NCMIR for the use of electron microscopy facilities. J.A. would like to thank Dr. Hugo Celio and Dr. Anthony Dylla for their thoughtful discussions concerning these experiments. M.S. and J.A. would like to thank Emil Kim for the authorized use of table of contents figure. Y.S.M. would like to thank Ford URP program for partial support of her effort on this project.
PY - 2016/10/19
Y1 - 2016/10/19
N2 - Fluoroethylene carbonate (FEC) as an electrolyte additive can considerably improve the cycling performance of silicon (Si) electrodes in Li-ion batteries. However, the fundamental mechanism for how FEC contributes to solid electrolyte interphase (SEI) morphological changes and chemical composition is not well understood. Here, scanning transmission electron microscopy coupled with electron energy loss spectroscopy gives a comprehensive insight as to how FEC affects the SEI evolution in terms of composition and morphology throughout electrochemical cycling. In the first lithiation cycle, the electrode cycled in ethylene carbonate (EC): diethylene carbonate (DEC) forms a porous uneven SEI composed of mostly Li2CO3. However, the electrode cycled in EC/DEC/FEC is covered in a dense and uniform SEI containing mostly LiF. Interestingly, the intrinsic oxide layer (Li x SiO y) is not observed at the interface of electrode cycled in EC/DEC/FEC after 1 cycle. This is consistent with fluoride anion formation from the reduction of FEC, which leads to the chemical attack of any silicon-oxide surface passivation layer. Furthermore, surface sensitive helium ion microscopy and X-ray photoelectron spectroscopy techniques give further insights to the SEI composition and morphology in both electrodes cycled with different electrolytes.
AB - Fluoroethylene carbonate (FEC) as an electrolyte additive can considerably improve the cycling performance of silicon (Si) electrodes in Li-ion batteries. However, the fundamental mechanism for how FEC contributes to solid electrolyte interphase (SEI) morphological changes and chemical composition is not well understood. Here, scanning transmission electron microscopy coupled with electron energy loss spectroscopy gives a comprehensive insight as to how FEC affects the SEI evolution in terms of composition and morphology throughout electrochemical cycling. In the first lithiation cycle, the electrode cycled in ethylene carbonate (EC): diethylene carbonate (DEC) forms a porous uneven SEI composed of mostly Li2CO3. However, the electrode cycled in EC/DEC/FEC is covered in a dense and uniform SEI containing mostly LiF. Interestingly, the intrinsic oxide layer (Li x SiO y) is not observed at the interface of electrode cycled in EC/DEC/FEC after 1 cycle. This is consistent with fluoride anion formation from the reduction of FEC, which leads to the chemical attack of any silicon-oxide surface passivation layer. Furthermore, surface sensitive helium ion microscopy and X-ray photoelectron spectroscopy techniques give further insights to the SEI composition and morphology in both electrodes cycled with different electrolytes.
KW - electron energy loss spectroscopy
KW - fluoroethylene carbonate
KW - scanning transmission electron microscopy
KW - solid electrolyte interphases
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U2 - 10.1002/admi.201600438
DO - 10.1002/admi.201600438
M3 - Article
AN - SCOPUS:84991666784
VL - 3
JO - Advanced Materials Interfaces
JF - Advanced Materials Interfaces
SN - 2196-7350
IS - 20
M1 - 1600438
ER -