Journal
ENERGY & ENVIRONMENTAL SCIENCE
Volume 14, Issue 9, Pages 4882-4889Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/d1ee01678d
Keywords
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Funding
- Key-Area Research and Development Program of Guangdong Province [2020B090919001]
- National Natural Science Foundation of China [21802065, 22078144]
- Shenzhen Clean Energy Research Institute [CERI-KY-2019-003]
- Shenzhen Key Laboratory of Solid State Batteries [ZDSYS20180208184346531]
- Guangdong Innovative and Entrepreneurial Research Team Program [2019ZT08C044]
- Shenzhen Science and Technology Program [KQTD20190929173815000]
- Shenzhen DRC project [[2018]1433]
- Development and Reform Commission of Shenzhen Municipality
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The microstructure of the solid electrolyte interface on graphite was revealed using cryo-transmission electron microscopy, showing that additives can stabilize and reduce the thickness of the solid electrolyte interface, preventing further exfoliation of the graphite surface.
Revealing the atomic structures of the solid electrolyte interphase (SEI) is challenging due to its sensitivity to electron beam and environmental factors such as moisture and oxygen. Here, we unveiled the atomic structures and phase distribution of the fragile solid electrolyte interphase (SEI) on graphite using ultra-low-dosage and aberration-corrected cryo-transmission electron microscopy (cryo-TEM). It is known that propylene carbonate electrolyte can exfoliate a graphite anode and damage its structural integrity. Surprisingly, ethylene carbonate-diethyl carbonate can also damage the surface of the graphite anode by exfoliation even with an initial formation protocol of constant-current charging (0.05C) for three hours and then 0.1C for another 3 hours at 45 degrees C: we hypothesize that the exfoliated graphene layers embedded in the SEI enhance local electron channeling, which induces an ever-growing, thick SEI layer with randomly distributed graphene, Li2O, and Li2CO3 nano-crystals. Using the same formation protocol but with 1 wt% vinylene carbonate (VC), triphenyl phosphate (TPP), or ethylene sulfate (DTD) or 10 wt% monofluoroethylene carbonate (FEC) as the additive is found to cause solid deposition prior to the graphite exfoliation instability, which generates a stable and thin SEI (<90 nm) on the graphite surface which prevents further exfoliation of graphite and rapidly suppresses the decomposition of electrolyte in the later cycles. When using a slower formation protocol including 2 cycles between 3.0 and 4.2 V at a rate of 0.01C at room temperature, graphite exfoliation is dramatically reduced, but is still observable initially.
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