Microporous electrode

In plastic Li-ion batteries, 20 wt% of dibulyl phthalate is added to the electrode composition to be molded and later to be extracted with diethyl ether. This results in the desired microporous electrode. ... 

As is the case with fuel cells, depolarized cathodes have been considered for years but have not yet found wide commercial use in the chlor-alkali indusby. Reports of work in the 1970s and 1980s [117,118] described the use of solid-polymer electrolyte systems. Microporous electrodes are necessary for electrical continuity in these cells, and the cathode reaction takes place in the interior of the gas-diffiision electrode. Operating deficiencies include the gradual penetration of gas channels by caustic solution and the possibility of bulk flow of catholyte into the gas side of the electrodes. Section 17.2.2.2 describes more recent work that addresses these deficiencies. The first conunercial applications are beginning to appear. 

Deng H, Mao H, Liang B, Shen Y, Lu Z, Xu H (1996) Aggregation and the photoelectric behavior of tetrasulfonated phthalocyanine adsorbed on a TiOj microporous electrode. J Photochem Photobiol A 99 71-74... 

Separator s a physical barrier between the positive and negative electrodes incorporated into most cell designs to prevent electrical shorting. The separator can be a gelled electrolyte or a microporous plastic film or other porous inert material filled with electrolyte. Separators must be permeable to ions and inert in the battery environment. 

The thin backweb, typically 0.2 mm thick with a porosity of 60 percent yields excellent electrical resistance values of 50 rafl cm2, permitting further optimization of high-performance battery constructions. These require very thin electrodes due to the overproportionally increasing polarization effects at higher current densities and consequently also low distances most modern versions have separators only 0.6 mm thick. Such narrow spacings enforce microporous separation ... 

Table 12 shows the physicochemical data of separators used in open stationary batteries. Since the emphasis is on low acid displacement, low electrical resistance, and high chemical stability, the phenolic resin-resorcinol separator is understandably the preferred system, even though polyethylene separators, especially at low backweb, are frequently used. For large electrode spacing and consequently high separation thickness, microporous as well as sintered... 

Batteries with gelled electrolyte have been shown to require a separator in the conventional sense, to secure spacing of the electrodes as well as to prevent any electronic shorts the latter is achieved by microporous separators. An additional important criterion is minimal acid displacement, since these batteries — in comparison with batteries with liquid electrolyte — lack the electrolyte volume share taken up by gelling and by the cracks. 

Battery makers sometimes view separators with disdain the separator is needed but does not actively contribute to battery operation. Consequently, very little work (relative to that on electrode materials and electrolytes) is directed towards characterizing separators. In fact, development efforts are under way to displace microporous membranes as battery separators and instead to use gel electrolytes or polymer electrolytes. Polymer electrolytes, in particular, promise enhanced safety by elimi-... 

Dasgupta and Jacobs [29] patented a concept of using a gel layer in combination with a microporous membrane. The gel layer acts as an adhesive bridge between separator and electrodes, just as in the flat pack Zn/MnC cell [30], The microporous membrane (for example, Celgard membrane) provides excellent mechanical... 

EC, electrode cells EC, filling chambers SP, silicon packings C, rectangular capillary M, microporous PTFE membranes E, platinum planar electrodes S, stoppers [68. ... 

Fignre 27.3 shows a typical spectroelectrochemical cell for in sitn XRD on battery electrode materials. The interior of the cell has a construction similar to a coin cell. It consists of a thin Al203-coated LiCo02 cathode on an aluminum foil current collector, a lithium foil anode, a microporous polypropylene separator, and a nonaqueous electrolyte (IMLiPFg in a 1 1 ethylene carbonate/dimethylcarbonate solvent). The cell had Mylar windows, an aluminum housing, and was hermetically sealed in a glove box. 

Electrochemical capacitors are power storage devices, whose performance is based on the charge accumulation from an electrolytic solution through electrostatic attraction by polarized electrodes. The capacitance of this system is directly proportional to the electrode surface, therefore carbons are very efficient for this application because of various possibilities of their modification and creation of a controlled pore size distribution [1-3]. The electrostatic attraction of ions takes place mainly in micropores, however, the presence of mesopores is necessary for efficient... 

High porosity carbons ranging from typically microporous solids of narrow pore size distribution to materials with over 30% of mesopore contribution were produced by the treatment of various polymeric-type (coal) and carbonaceous (mesophase, semi-cokes, commercial active carbon) precursors with an excess of KOH. The effects related to parent material nature, KOH/precursor ratio and reaction temperature and time on the porosity characteristics and surface chemistry is described. The results are discussed in terms of suitability of produced carbons as an electrode material in electric double-layer capacitors. 

Recent reports describe the use of various porous carbon materials for protein adsorption. For example, Hyeon and coworkers summarized the recent development of porous carbon materials in their review [163], where the successful use of mesoporous carbons as adsorbents for bulky pollutants, as electrodes for supercapacitors and fuel cells, and as hosts for protein immobilization are described. Gogotsi and coworkers synthesized novel mesoporous carbon materials using ternary MAX-phase carbides that can be optimized for efficient adsorption of large inflammatory proteins [164]. The synthesized carbons possess tunable pore size with a large volume of slit-shaped mesopores. They demonstrated that not only micropores (0.4—2 nm) but also mesopores (2-50 nm) can be tuned in a controlled way by extraction of metals from carbides, providing a mechanism for the optimization of adsorption systems for selective adsorption of a large variety of biomolecules. Furthermore, Vinu and coworkers have successfully developed the synthesis of... 

O. Ikeda, M. Ohtani, T. Yamaguchi, and A. Komura, Direct electrochemistry of cytochrome c at a glassy carbon electrode covered with a microporous alumina membrane. Electrochim. Acta 43, 833—839 (1998). 

Kavan, L. Rathousky, J. Gratzel, M. Shklover, V. Zukal, A. 2001. Mesoporous thin filmTi02 electrodes. Microporous Mesoporous Mater. 44 653-659. 

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