A transmission electron microscopy study of crack formation and propagation in electrochemically cyc-资料下载-阿美特克科学仪器部-普林斯顿及输力强电化学

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A transmission electron microscopy study of crack formation and propagation in electrochemically cyc

阅读：3038 发布时间：2014-9-2

Subsurface defects and local compositional changes that occurred in graphite anodes subjected to cyclic

voltammetry tests (vs. Li/Li+, using an electrolyte consisting of 1 M LiClO4 in a 1:1 volumetric mixture

of ethylene carbonate and 1,2-dimethoxy ethane) were investigated using high-resolution transmission

electron microscopy (HR-TEM). Cross-sections of anodes prepared by focused ion beam (FIB) milling

indicated that graphite layers adjacent to solid electrolyte (SEI)/graphite interface exhibited partial

delamination due to the formation of interlayer cracks. The SEI layer formed on the graphite surface consisted

of Li2CO3 that was identified by

{1 1 0}

and

{0 0 2}

crystallographic planes. Lithium compounds,

LiC6, Li2CO3 and Li2O, were observed on the surfaces of separated graphite layers. Deposition of these cointercalation

compounds near the crack tip caused partial closure of propagating graphite cracks during

electrochemical cycling, and possibly reduced the crack growth rate. Graphite fibres that were observed

to bridge crack faces likely provided an additional mechanism for the retardation of crack propagation.