Carbonaceous liquid electrolytes

As a result, the acid strength of the proton is approximately equivalent to that of sulfuric acid in nonaqueous media. In view of the excellent miscibility of this anion with organic nonpolar materials, Armand et al. proposed using its lithium salt (later nicknamed lithium imide , or Lilm) in solid polymer electrolytes, based mainly on oligomeric or macro-molecular ethers. In no time, researchers adopted its use in liquid electrolytes as well, and initial results with the carbonaceous anode materials seemed promising. The commercialization of this new salt by 3M Corporation in the early 1990s sparked considerable hope that it might replace the poorly... 

It is generally accepted that no solvent is thermodynamically stable towards lithium, even carbonaceous anodes. Polymer electrolytes, owing to their solid-like nature and much lower liquid content, are less reactive than their liquid electrolyte counterparts. 

Thus, at temperatures lower than the liquid us temperature (usually above —20 °C for most electrolyte compositions).EC precipitates and drastically reduces the conductivity of lithium ions both in the bulk electrolyte and through the interfacial films in the system. During discharge, this increase of cell impedance at low temperature leads to lower capacity utilization, which is normally recoverable when the temperature rises. However, permanent damage occurs if the cell is being charged at low temperatures because lithium deposition occurs, caused by the high interfacial impedance, and results in irreversible loss of lithium ions. An even worse possibility is the safety hazard if the lithium deposition continues to accumulate on the carbonaceous surface. 

Due to the core importance of the SEI formation on carbonaceous anodes, the majority of the research activities on additives thus far aim at controlling the chemistry of the anode/electrolyte interface, although the number of publications related to this topic is rather limited as compared with the actual scale of interest by the industry. Table 9 summarizes the additives that have been described in the open literature. In most cases, the concentration of these interface-targeted additives is expected to be kept at a minimum so that the bulk properties of the electrolytes such as ion conduction and liquid ranges would not be discernibly affected. In other words, for an ideal anode additive, its trace presence should be sufficient to decouple the interfacial from bulk properties. Since there is no official standard available concerning the upper limit on the additive concentration, the current review will use an arbitrary criterion of 10% by weight or volume, above which the added component will be treated as a cosolvent instead of an additive. 

This section addresses the role of chemical surface bonding in the electrochemical oxidation of carbon monoxide, CO, formic acid, and methanol as examples of the electrocatalytic oxidation of small organics into C02 and water. The (electro)oxidation of these small Cl organic molecules, in particular CO, is one of the most thoroughly researched reactions to date. Especially formic acid and methanol [130,131] have attracted much interest due to their usefulness as fuels in Polymer Electrolyte Membrane direct liquid fuel cells [132] where liquid carbonaceous fuels are fed directly to the anode catalyst and are electrocatalytically oxidized in the anodic half-cell reaction to C02 and water according to... 

The major fraction of the submicrometer particles in polluted atmospheres is a mixture of carbonaceous compounds and inorganic salts, mainly sulfates, nitrates, and chlorides, the main cation being ammonium (e.g., Stelson and Seinfeld 1981). Due to the hygroscopic properties of the given mixture in many cases (at higher relative humidities or lower temperatures), the electrolytes will be present in liquid state (Pilinis and Seinfeld 1987). Soluble trace metal compounds attached to such particles will dissolve and the metals be present in the ionic state. After an eventual drying of the particle the metals are expected to appear as sulfates or mixed salts. 

In our LPBs, surfaces of graphite particles were modified with amorphous carbonaceous materials to avoid PC decomposition and our GPEs had comparable ionic conductivity to liquid nonaqueous electrolytes and also exhibited excellent compatibility with graphite. 

It is clear that a system that can utilize a liquid fuel directly at the fuel cell anodes would be particularly appealing in small fuel cell applications. As mentioned earlier, at this time metiianol is the only carbonaceous species that can both serve as a practical fuel and provide reasonable electrochemical performance at the fuel cell anode. Substantial research and development efforts have been directed at direct-methanol fuel cells using PEM electrolyte for more than a decade, in the context of small, field-deployable systems. 

Ionic liquids (IL) are common electrolytes for use in ionic and c acitive actuators operable in air. IL fills the porous structure of the carbonaceous electrodes and tire intercoimected porous network in the polymeric separator in-between the electrodes. IL-incorporated polymer can be required also as a binder in the electrodes. As an advantageous property, carbon nanotubes form a highly viscous gel - a so-called bucky-gel, when mixed with ionic Uquids (Fukushima et al. 2005 Fukushima et al. 2003). The bucky-gel electrodes do not requite addition of any polymeric binder, which, in turn, helps to retain good electrical conductivity along the electrodes. 

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