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A two-dimensional thermal model is developed to establish a standard for the simulation of spirally wound cells. It properly deals with the geometric characteristics and the boundary conditions to avoid the distorted simulation results due to improper approximation of the spiral geometry. Furthermore, the flexible architecture makes it possible that the precision of the numerical solutions can be elevated by spending more time on calculation. According to the simulation of lithium batteries under natural convection, the hottest temperatures are in a circular region near the liquid-filled hollow core but not at the exact center. Furthermore, radiation contributes as much as 53.6% to the heat dissipation if the surface emissivity approaches unity. Adopting an air flow parallel to the cylinder axis is effective to suppress the surface temperature, but the hottest temperature inside a battery remains high if a battery has a large radius. The heat dissipation rate of an air flow perpendicular to the cylinder axis is slightly lower than that of a parallel flow, and a battery case with high thermal conductivity is suggested to maintain the temperature uniformity of a battery.

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Poly(N-vinyl-2-pyrrolidone) (PVP)-capped Pt nanoclusters were deposited on indium-tin oxide glass via a simple two-step dip-coating process. This new type of electrode was examined by atomic force microscopy, inductively coupled plasma-atomic emission spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. The results reveal that the Pt nanoclusters sized about 10-20 nm show a noticeable catalytic effect on tri-iodide reduction although they are surrounded by PVP entanglements. The new electrolyte can serve as a counter electrode in dye-sensitized solar cells (DSSCs). In addition, we have found a counter action between the nanosized effect and the hindrance effect by PVP entanglement on both catalytic kinetics and ion diffusivity. Finally, at certain PVP levels, the so-prepared electrode's performance is similar to a smooth Pt metal sheet electrode. So this process could potentially reduce manufacturing costs for DSSCs, which further enhances the feature of DSSCs in furnishing low cost solar electricity.