PC + FEC

Figure 15 shows CVs of HOPG basal plane in the first cycle between 2.9 and 0.0 V at 0.5 mV s" in the presence of the additives. " In each solution, a distinct reduction peak appeared in the range 1.0-1.5 V in the first cycle. The peak potentials were 1.3, 1.1 and 1.0 V in PC+ VC, PC + FEC, and PC + ES, respectively. These reduction peaks disappeared in the second cycle, and hence are attributed to irreversible decomposition of the electrolyte solutions that are closely related to SEI formation. 

F. 3 Voltage profiles in the first cycle of Li/mesocarbon microbead (MCMB) half cells with 1 M LiPFa in bi-solvent and tri-solvent electrolytes containing EC, PC, FEC (labeled as MFPC in the graph), and TFPC. Reproduced with permission [106]. Copyright 2010 Elsevier... 

Considering the virtually zero solubility of LiF in nonaqueous media, McMillan et al. synthesized the fluorinated counterpart of CIEC. As expected, the shuttle phenomenon was eliminated because of the fluorination, as evidenced by the quantitative Coulombic efficiency, while a similar SEI effect was maintained, since FEC/PC mixed solvent can support reversible lithiation/delithiation of the graphitic anode materials. However, capacity was observed to fade by 37% in 200 cycles. Follow-up work on this solvent has been minimal. 

The total cost of a purification carried out by chromatography, or production cost (PC), can be divided in three different components, the fixed costs, FiC, the operating or proportional costs, CKl, and the cost of the lost feed, FeC... 

In addition to carbonate solvents, partially flnorinated organic solvents have also been developed in parallel. It has been reported the chemical and electrochanical stability of solvents could be remarkably improved by the substitution of C-H bonds with C-F bonds [439,440]. Nanbu et al. [441] found that although the ionic conductivity of fluoroethylene carbonate (FEC) electrolyte containing 1 M TEABF4 was slightly lower than the PC-based electrolyte, the specific capacitance and rate performance achieved in the FEC-based electrolyte were improved compared to the PC-based electrolyte. It was also found the solubility of TEMABF4 in the FEC could... 

Ethylene carbonate (EC) and propylene carbonate (PC) have favorable physical and electrochemical properties such as high relative permittivity, high donicity, and relatively wide potential window. The direct fluorination of EC was successfully carried out to provide 4-fluoro-l,3-dioxolan-2-one (fluoroethylene carbonate, FEC) as shown in Scheme 2.3 [20], The fluorination of EC was strongly dependent on a choice of a reaction medium and no solvent was preferred from the viewpoint of conversion. FEC was further fluorinated to give three di-fluorinated derivatives. On the other hand, FEC was also prepared from 4-chloroethylene carbonate by exchange with KF [21], FEC was tested as an electrolyte additive for rechargeable lithium cells [21, 22] and is now practically used [23, 24],... 

Several electrolyte additives have been used to form stable SEI layers and improve cyclability of silicon anodes. Doh et al. [Ill] used 5% 4-fluoroethylene carbonate (FEC) in the electrolyte of 1.0-M LiPFs in EC/DMC/EMC/PC at a volume ratio of 4 3 3 1 when investigating silicon/carbon composites formed by polyaniline carbonization. They found that the addition of FEC to the electrolyte increased the initial discharge capacity of the silicon/carbon composites when compared with the electrolyte without FEC. Choi et al. [112] reported that the... 

Figure 1.11. Gahanostatic curve of a composite Si electrode [Si/Cb/CMCJ [70/18/12J cycled in the electrolyteLiPFsinEC PC 3DMC (+1%FEC)...

The BPIX readout and control system consists of three main parts (see Sect. 7.3) the analog readout link between the modules and the FED, the digital control link between the modules and the pxFEC and the slow control link between the CCUs and the trFEC. At P5 the FED and FEC boards are installed in different VME crates in the CMS underground service room. Since one crate of electronic boards is controlled by one PC, the software used for communication is implemented as a distributed system. 

Figure 14 Variations of the discharge capacity with cycle number for natural graphite powder (NG-7) in 1 M LiClO /PC containing 3 wt% VC, FEC, and ES. Reproduced from [46] with...

Figure 17 AFM images of expanded areas (10 x 10 pm) and height profiles of HOPG basal plane surface obtained at 2.9 V after the first cycle of CV in 1 M LiClO /PC containing 3 wt% (a) VC, (b) FEC, and (c) ES. The square in each image shows the area observed by AFM in the first eycle, where the precipitates were scraped off by the AFM tip. Reproduced from [46] with permission of The American Chemical Society.

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