In lithium-ion battery electrode processing, obtaining good wetting and adhesion of the electrode dispersion to the current collector foil is essential for achieving high capacity and good long-term performance. The surface tension of LiFePO 4 aqueous dispersions is much higher than the surface energy of untreated Al foil due to the high surface tension of water (72.8 mN/m), which causes inferior wetting during the coating step. In this work it has been shown that the surface energy of Al foil is significantly increased by corona plasma treatment. Consequently, the wetting and adhesion of the LiFePO 4 aqueous dispersion to the Al foil are dramatically improved, as evidenced by contact angle measurements, adhesion energy calculations and interfacial tension calculations. The LiFePO 4 cathodes with corona treated Al foil exhibited superior capacity (∼20 mAh/g improvement) with no increase in capacity fade at 0.5C/−0.5C cycling compared to an identical electrode without treatment.

The wetting properties of proton exchange membrane fuel cell (PEMFC) gas diffusion layers (GDLs) were quantified by surface characterization measurements and modeling of material properties. Single-fiber contact-angle and surface-energy (both Zisman and Owens–Wendt) data of a wide spectrum of GDL types are presented to delineate the effects of hydrophobic postprocessing treatments. Modeling of the basic sessile-drop contact angle demonstrates that this value only gives a fraction of the total picture of interfacial wetting physics. Polar forces contributed 10–20× less than dispersive forces to the composite wetting of GDLs. Internal water contact angles obtained from the Owens–Wendt analysis were measured at 13–19° higher than their single-fiber counterparts. An inverse relationship was found between internal contact angle and both Owens–Wendt surface energy and percent polarity of the GDL. The most sophisticated PEMFC mathematical models use either experimentally measured capillary pressures or the standard Young–Laplace capillary-pressure equation. Based on the results of the Owens–Wendt analysis, an advancement to the Young–Laplace equation was proposed for use in these mathematical models, which utilizes only solid surface energies and a fractional surface coverage of a fluoropolymer. Capillary constants for the spectrum of analyzed GDLs are presented for the same purpose.

This article reports on the interfacial behavior of large liquid-phase polycyclic aromatic hydrocarbons in pitches that are common precursors to carbon materials. Experiments were conducted to identify preferred angles of molecular orientation ("surface anchoring" states) and to measure contact angles on a variety of well-characterized substrates. The results show that the large disklike polyaromatic molecules exhibit anomalously weak noncovalent interactions with a variety of surfaces, a fact that we attribute to inhibition of dispersion forces due to geometric mismatch at the interface. It is further found that large polyaromatics prefer edge-on molecular orientation at most interfaces, a configuration that preserves internal aromatic π-π bonds at the expense of inhibited π-surface bonds. A theory of π-π bond preservation is proposed to explain many aspects of wetting, adsorption, anchoring, and supramolecular assembly in this important class of compounds, including the formation mechanism for the classic bipolar Brooks-Taylor mesocarbon spheres. The results are used to discuss the mechanisms of structure selection in carbon materials prepared at high and low temperatures. The results are also used to demonstrate a new approach for molecular engineering of carbon that employs anchoring templates to synthesize new materials with preprogrammed patterns of graphene layer orientation.

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