Lithium hexafluorophosphate LiPF

Most liquid electrolytes used in commercial lithium-ion cells are nonaqueous solutions, in which roughly 1 mol dm of lithium hexafluorophosphate (LiPF ) salt is dissolved in a mixture of carbonate solvents selected from cyclic carbonates, e.g., ethylene carbonate (EC) and propylene carbonate (PC), and linear carbonates, e.g., dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), as listed in Table 2.1 [1]. 

The standard composition of an electrolyte in LlBs is a mixture of cycUc carbonates (such as ethylene carbonate (EC) and propylene carbonate (PC)) and chain carbonates (such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC abbreviated as MEC below), and diethyl carbonate (DEC)), to which about 1 mol/L of a lithium salt (such as lithium hexafluorophosphate (LiPF )) is added. Ube Industries, Ltd. discovered that if small amounts of impurities exist in the electrolyte, decomposition current generated from the impurities begins to flow, which leads to the formation of undesirable thick SET This spurred the development of a pioneering high-grade purification process for the base electrolyte in 1997 [16]. High purity is a key feature of functional electrolytes developed by Ube Industries, Ltd. and enables production of transparent and chemically stable electrolytes, in contrast to the conventional electrolytes which were less stable and brown owing to its low purity (Fig. 3.1). 

Another key battery component is the electrolyte. While many possible electrolytes are being developed, we have selected lithium hexafluorophosphate (LiPFe) in a solvent of EC and DMC. Little information exists on the production of LiPFe, so its impact, although estimated on the basis of data presented by Espinosa et al. [12], is somewhat uncertain. Given the potentially harmfiil nature of the compound, it is of interest to consider what its fate may be during the battery recycling process, which we address in Section 4. 

Before most of the DSC studies, including the one discussed below, the materials are charged to a desired voltage in the electrochemical coin cells (the name refers to their approximate size and shape several models exist) against Li/Li+ anode (half-cells). After the disassembly of the cell, the cathode is taken out and washed in an organic solvent to remove traces of lithium hexafluorophosphate (LiPFe), dried, and loaded into the DSC pan. 

Lithium hexafluorophosphate LiPF, 151.9 HjO (15ppm) HE (lOOppm) Most commonly used... 

Lithium hexafluorophosphate (LiPFs) is the most frequently used salt in commercially available secondary lithium-ion batteries. As mentioned above, liPFe moderately fulfills most of the required properties. LiPFg is up to now one of the most eflflcient salts in lithium-ion batteries. Its conductivity is similar to that of LiAsFfi in blends of organic solvents (e.g., 10.7 mS-cm in 1 M EC/DMC at ambient temperature [80]). 

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