Coated anodes composition/preparation

Perhaps more important than cost is the solution to the crucial problem of interfacial contacts that always plagues homogeneous GPE films prepared from traditional approaches. Since both cathode and anode composite materials are coated on their substrates with the same PVdF—HEP copolymer as the binder, the in situ gellification following the electrolyte activation effectively fuses the three cell components into an integrated multilayer wafer without physical boundaries, so that the interfaces between anode and electrolyte or cathode and electrolyte are well extended into the porous structures of these electrodes, with close similarity to the interfaces that a liquid electrolyte would access. 

Polyaniline-nitrilic rubber composites have been prepared using rubber-coated anodes for electropolymerization. The resultant material has the mechanical properties of a crosslinked elastomer with the electrical and electro-optical properties of polyaniline. The polymer composite properties vary markedly with the electrolyte used during electropolymerization. 

Coating NiO has not been so successful. To avoid the barrier that a uniform coat of NiO with a metal could rise for the lithium transport, a composite NiO/Co-P has been synthesized with NiO particles 200 nm in size, and 30 nm thick granular plating particles of Co-P [518]. This anode delivered the discharge and charge capacities 560 and 540 mAh g, respectively, after 50 cycles at current density 100 mA g . At the higher current densities of 200, 500, and 1000 mA g, the reversible capacities were 560,480, and 270 mAh g, respectively. Among NiO/Ni composites [519-521], the best results over 50 cycles have been found on self-supported nickel-coated NiO arrays prepared by chemical bath depositiOTi of NiO flake arrays... 

The reaction mixture is filtered. The soHds containing K MnO are leached, filtered, and the filtrate composition adjusted for electrolysis. The soHds are gangue. The Cams Chemical Co. electrolyzes a solution containing 120—150 g/L KOH and 50—60 g/L K MnO. The cells are bipolar (68). The anode side is monel and the cathode mild steel. The cathode consists of small protmsions from the bipolar unit. The base of the cathode is coated with a corrosion-resistant plastic such that the ratio of active cathode area to anode area is about 1 to 140. Cells operate at 1.2—1.4 kA. Anode and cathode current densities are about 85—100 A/m and 13—15 kA/m, respectively. The small cathode areas and large anode areas are used to minimize the reduction of permanganate at the cathode (69). Potassium permanganate is continuously crystallized from cell Hquors. The caustic mother Hquors are evaporated and returned to the cell feed preparation system. 

One way to control the reactivity of the intermediates appearing is the electrolysis performance at high concentrations of substrate up to 90% of the electrolyte composition. Additionally, a good mass transport from the anode into bulk is important to avoid electrochemical incineration. For such preparative work a conceptually novel architecture is required. The two major issues are an electrolysis cell on the micro scale and avoiding nonemployed volumes by efficient stirring of the electrolyte. A micro electrolysis cell with volumes of 0.7-4 mL has been designed (Fig. 6). All components are made of Teflon or coated by this inert material. A cylindrical... 

Liu, Y, Matsumura, T, Imanishl, N., Hirano, A., Ichikawa, T, and Thkeda, Y. (2005]. Preparation and characterization of Si/C composite coated with polyaniline as novel anodes for Li-ion batteries, Electrochem. Solid St, 8, pp. A599-A602. 

Y. Liu, T. Matsumura, N. Imanishi, A. Hirano, T. Ichikawa, Y. Takeda, Preparation and Characterization of SPC Composite Coated with Polyaniline as Novel Anodes for Li-Ion Batteries. Electrochem. Solid-State Lett. 2005, 8, A599. 

Xiao, X. F., Liu, R.F., and Zheng, Y.Z. Hydoxyapatite/titanium composite coating prepared by hydrothermal-electrochemical technique. Mater. Lett., 59,1660-1664 (2005). Yang, B., Uchida, M., Kim, H. M., Zhang, X., and Kokubo, T. Preparation of bioactive titanium metal via anodic oxidation treatment. Biomaterials, 25,1003-1010 (2004). 

The composites were typically prepared by means of milling the ingredients (silicon and graphite powders) for different time intervals. In addition, some samples were coated with a layer of hard carbon deposited from a gaseous phase by means of the thermal vapor deposition (TVD) technique. The volume resistance of the silicon powder was 1,500 Q cm, while that of the carbon-coated composite was only around 100 mQ cm. Composites containing comparatively large silicon particles (>1 pm) could cycle up to 50 cycles when the insertion capacity is limited (<800 mA h g ). These improved characteristics are ascribed mainly to the continuous electric networks around the silicon particles. In contrast, particulate silicon anodes, containing only silicon and PVDF, do not show considerable reversibility and deteriorate completely in just a few cycles. 

Various series of experiments were carried out on different types of samples. All samples consisted of three layers, the Ni-YSZ substrate, Ni-YSZ anode and YSZ electrolyte. The substrates were prepared by the Coat-Mix process and warm pressing. The chemical composition is 56 wt.% NiO and 44 wt.% YSZ for both the Coat-Mix substrate and the anode. Characterization of the Ni-YSZ-cermets with respect to redox tolerance was performed at free standing samples with dimensions 50x25 mm and a thickness of 1.5. 1.0 or 0.5 mm to investigate the influence of the re-oxidation temperature, time of re-oxidation, incident air flow, substrate thickness and substrate porosity on the mechanical integrity of the substrate and other cell components. Examples of the free standing samples that were used for the tests are shown in Fig. 1. 

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