PC-based solutions

The main conclusions from this study are that the electron-drawing fluorine substituent produces a decrease in the association constant by a factor of about 3 for PC-based solutions and of 5.5 for solutions in DME [81] (cf. also Fig. 5). The consequence is an increase in the maximum of conductivity by about 30 percent (PC) and about 80 percent (DME). 

Modern factory and industrial automation is more flexible and open and meant towards higher productivity. These systems replace conventional relay or solid state control systems, with extensive use of open programmable electronics in all types of scalable and demanding solutions. Modem safety integrated safety-related controllers of various designs with a variety of hardware and software architectures, including PC-based solutions, cover all sectors and types of factory automations. Associated standards for factory automations are ... 

Charge and Discharge Characteristics of Graphite Anode in EC- and PC-Based Solutions... 

These include chloroethylene carbonate (Cl-EC), vinylene carbonate (VC), ethylene sulfite (ES), propylene sulfite (PS), fluoroethylene sulfite (EEC), a-bromo-y-butyrolactone, methyl chloroformate, f-butylene carbonate (f-BC), and 12-crown (12-C-4). In addition to these additives, co-solvents, such as dimethylsulfoxide (DMSO), diethoxymethane (DEM), dimethoxymethane (DMM), and diethoxyethane (DEE) are also effective for stable SEI formation in PC-based solutions. The molecular structures of these additives and co-solvents are summarized in Figure 13. It seems that all these additives give stable SEI layers on graphite surface ... 

Figure 13 SEI-forming ability of various cyclic carbonates, and effective additives and co-solvents in PC based solutions. (O) good SEI-forming ability (X) poor SEI-forming ability.

The additives that have been reported so far to be effective to form stable SEI in PC-based solutions are classified into two groups. One is a group of additives that decomposed at potentials higher than 0.9 V before cointercalation of PC takes place. VC, EEC, ES and other halogenated carbonates belong to this group. The other is ethers that preferentially solvate lithium ion and suppress co-intercalation of PC. 

Many efforts have been dedicated to find proper additives to PC-based solutions that would enable practical applications of PC. Some successes have been reported, including the addition of chloroethylene carbonate (CEC), other... 

Thermodynamic analysis indicates that (S)nLP(VC) (S = EC and PC n = 1, and 2) could be generated through the addition reactions of the LC(S) (n = 1-3 S = EC and PC) clusters with the VC molecule in EC/PC-based solutions, as a small amount of VC is introduced. To explore the reasons behind the functioning mechanism of VC as an efficient additive of EC/PC-solutions which greatly improves the reversible capacity of LlBs, reductive decompositions of the clusters (S)nLi (VC) are investigated. 

Table 3 also shows that two acetylene (CH CH) involved reactions, 8 and 9, are rather less favorable than ethylene gas evolution reactions. It is safe to conclude that for the VC-containing EC(PC)-based solutions the amount of ethylene (propylene) gas might be less than that for VC-free solution, and that CO could be generated due to the presence of VC. 

Another interesting feature is that VC and ES, two well-defined additives to PC/EC solutions in Li-ion batteries, have approximately 5 kcal/mol lower binding energy with Lf than EC and PC. This indicates that incorporating specific additives to the EC/PC-based solutions, can somewhat suppress cointercalation of solvent molecules. This is consistent with the recent... 

It is also of interest to note that ethers cosolvent or addtioves to PC-based solutions, such as DMM and DME, have quiter higher binding energies with Li than PC and EC. It tells us that such solvents preferentially solvate Li and solvent co-intercalation may happen as they are present, which may prevent co-intercalation of PC and thereby suppress exfoliation of graphite layer for PC-based solutions. ... 

Remarks on the failure of PC and the efficiency of VC for the SEl layer formation in EC/PC-based solutions 272... 

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