Effect of Electrolyte Composition on SEI Properties

The properties of SEI electrodes, the growth rate of the SEI, the mechanism of dissolution and deposition, and the effects of various factors on SEI conductivity have been addressed elsewhere [1, 2] space limitations do not permit their repetition here. 

The interfacial phenomena in LiX/PE systems were studied extensively by Scro-sati and co-workers [3, 53, 130]. They found that the high-frequency semicircle in the impedance spectrum of LiC104/ P(EO)8 electrolyte (EO = ethylene oxide), 

Sloop and Lerner [132] showed that SEI formation can be affected by treatment of the cross-linked polymer, poly-[oxymeth-ylene oligo(oxyethylene)] (PEM) with an alkylating agent. Cross-linked films of PEM do not form a stable interface with lithium however, upon treatment with methyl iodide, / Ej stabilizes at 2000 Hem 1. Such an SEI is characterized by low conductivity, from 10 to 10 Q-Icm2, which is linear over the temperature range of 25-85 °C. 

An extensive study of the fundamental processes taking place in Li/CPE inter- 

The interfacial properties of gel electrolytes containing ethylene carbonate immobilized in a polyacrylonitrile (PAN) matrix with a lithium (bis)trifluoromethane sulfonimide (LiTFSI) salt have been studied 1139]. SEI stability appeared to be strongly dependent on the LiTFSI concentration. A minimum value of / SE1 of about 1000 Qcm2 was obtained after 200h 

The order of the interfacial resistance of the SEI on lithium covered by native fdm in ImolL LiX/PC solutions was determined by Aurbach and Zaban [20 25] from Nyquist plots. For the different salts, the order of was LiPF LiBp4 LiS03CF3 LiAsFg LiNCSOj CF3)2 LiBr, LiC104 [20]. The values for LiPF /PC and LiN(S02CF3)2/PC were about 800 and 23Qcm, respectively. The resistivity of the film was found to be directly proportional to the salt concentration, and the presence of CO2 in solutions considerably reduced the interfacial resistance. 

Such an SEI is characterized by low conductivity, from 10 to 10 Q cm, which is linear over the temperature range of 25-85 °C. 

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Effect of Electrolyte Composition on SEI Properties 16.4.3.1 Lithium Electrode... 

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