The electrolytic conductivities and limiting reduction and oxidation potentials for various organic liquid electrolytes based on quaternary onium salts have been measured to find better electrolytes for electrical double-layer capacitors. An electrolyte composed of tetraethylammonium cation, tetrafluoroborate anion, and propylene carbonate solvent showed well-balanced performance of high electrolytic conductivity, a wide stable potential window and resistance to hydrolysis. Among quaternary onium salts, triethylmethylammonium, ethylmethylpyrrolidinium, and tetramethylenepyrrolidinium tetrafluoroborate salts exhibited higher electrolytic conductivity than the conventional tetraethylammonium salt due to their much greater solubility.Ref. 25.

The limiting reduction and oxidation potentials and electrolytic conductivities of new quaternary ammonium salts were examined for electrochemical capacitor applications, whose anions have already been tested as lithium salts for lithium battery applications. The anodic stability was in the following order

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Electrolytic conductivities of lithium salts have been measured in equimolar mixtures of pr_o~vlene carbonate and either ethyl methyl carbonate or 1,2-dimethoxyethane at 25~ over a salt concentration range of 10 -~ to 10 3 mol dm 3. The limiting molar eonduetivities and association constants were calculated from the expanded Fuoss-Hsia equation. The Walden product of lithium ion was not enhanced by the addition of ethyl methyl carbonate as observed in the ease of 1,2-dimethoxyethane, due to the lack of specific solvation. LiPF6 and Li(CF3SO2),N in the propylene carbonate-ethyl methyl carbonate mixed solvent formed solvent-separated ion pairs, which resulted in decreased ion association. This work is a part of our systematic study ~-6 on the transport properties of nonaqueous electrolytes. Our previous study 5 on the conductometric analysis of lithium salts including LiC10~, LiBF4, LiPF6, LiAsF6, LiCF~SO3, Li(CF3SO~_)2N, and LiC~FgSO3 in propylene carbonate (PC) and ~-butyrolactone (GBL) is extended into mixtures of PC and either ethyl methyl carbonate (EMC) or 1,2-dimethoxyethane (DME).Mixed solvent systems such as LiC]O4/PC + DME and LiBF4/GBL + DME have a long history of use as nonaqueous electrolytes in primary Li/MnO2 and Li/(CF~)~ batteries because the addition of the ether increases the electrolytic conductivity due to its low viscosity. ;'8 However, ether solvents are often replaced with linear esters and carbonates, e.g., methyl formate (MF), methyl acetate (MA), dimethyl carbonate (DMC), and diethyl carbonate (DEC), because 4 V rechargeable lithium (ion) batteries using an Li~CoO2 cathode require solvents much more stable toward oxidation. 9-u Properties of ethylene carbonate (EC)-based electrolytes ~2-1~ and PC-based electrolytes ~'t~ containing these linear esters and carbonates have been investigated.Conduetometrie analysis on lithium salts in MF, ~;.,8 MA, ~9 and DMC 20 in the dilute range has been reported by by Salomon et aI., however, there is no report on mixed ABSTRACT We report studies of lithium insertion in a variety of organic precursors pyrolyzed below 1000~ These include two types of petroleum pitch, polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polypheny]ene sulfide (PPS), and epoxy novolac resin (ENR). Each of these materials shows reversible specific capacities for lithium of between 550 and 900 mAh/g when treated near 700~ The majority of this high capacity shows large hysteresis; that is the lithium is inserted near 0 V (vs. lithium metal) and removed near 1 V. Furthermore, the amount of capacity showing large hysteresis is well correlated to the hydrogen to carbon atomic ratio of the samples. As the pitch, PVC and PVDF samples are heated above 700~ the H/C ratio and the specific capacity decrease proportionally, suggesting that the hydrogen in these samples plays an important role. The PPS and ENR samples behave differently; as they are heated above 700~ the high capacity is maintained as H/C is reduced, although the voltage profile changes dramatically to one without sig...

In lithium ion battery composite anodes that are derived from graphite particles bound together by a polymeric binder of 5-7 wt %, it is well-known that the type and content of the binder influence the formation of a solid electrolyte interphase and the electrochemical behavior. However, the nature of the interaction between the graphite particles and binder has not been extensively studied. We describe here the interaction of poly(vinylidene fluoride) (PVDF) with graphite based on the characteristics of the precursor slurry and the surface chemistry and morphology of the final composite anodes. The slurry was characterized by dynamic viscosity measurements and the solid composite by atomic force microscopy, lateral force microscopy, electron probe X-ray microanalysis, and X-ray photoelectron spectroscopy. The final film properties correlate with the suspension viscosity, which varies over 6 orders of magnitude for eight different carbon samples. In the composite film, PVDF preferentially deposits on the edges and grain boundaries of the graphite particles with a maximum of 40% of the surface of graphite being covered by the polymer. We correlate an increase in the homogeneity of the PVDF distribution in the final composite film with an increase in the slurry viscosity and interpret this observation in terms of PVDF/graphite interaction.