Soiling of solar module cover glass can significantly reduce the module power output. Coatings can be applied to the cover glass surface to reduce adhesion and make the surfaces easier to clean. These coatings should be resilient and resistant to environmental damage. A hydrophobic anti-soiling coating was exposed to a variety of environmental and abrasion stress tests. The hydrophobic performance of the coating was measured by monitoring the water contact angle and the water roll off angle after exposure to a range of environmental and mechanical stress tests. The coating was shown to be highly resistant to damp heat and thermal cycling. However, it was degraded by UV exposure and damaged during abrasion tests. The coating was also exposed to outdoor testing to compare the laboratory results with real performance degradation.

Soiling of solar module cover glass is a serious problem for solar asset managers. It causes a reduction in power output due to attenuation of the incident light, and reduces the return on investment. Regular cleaning is required to mitigate the effect but this is a costly procedure. The application of transparent hydrophobic, anti-soiling coatings to the cover glass is a promising solution. These coatings have low surface energy and contaminants do not adhere well. Even if soiling does remain on the coated surface, it is much more easily removed during cleaning. The performance of the coatings is determined using the water contact angle and roll-off angle measurements. However, although hydrophobic coatings hold out great promise, outdoor testing revealed degradation that occurs surprisingly quickly. In this study, we report on results using laboratory-based damp heat and UV exposure environmental tests. We used SEM surface imaging and XPS surface chemical analysis to study the mechanisms that lead to coating degradation. Loss of surface fluorine from the coatings was observed and this appeared to be a major issue. Loss of nanoparticles was also observed. Blistering of surfaces also occurs, leading to loss of coating material. This was probably due to the movement of retained solvents and was caused by insufficient curing. This mechanism is avoidable if care is taken for providing and carrying out carefully specified curing conditions. All these symptoms correlate well with observations taken from parallel outdoor testing. Identification of the mechanisms involved will inform the development of more durable anti-soiling, hydrophobic coatings for solar application.

Thermal runaway is a major safety concern in the applications of Li-ion batteries, especially in the electric vehicle (EV) market. A key component to mitigate this risk is the separator membrane, a porous polymer film that prevents physical contact between the electrodes. Traditional polyolefin-based separators display significant thermal shrinkage (TS) above 100 °C, which increases the risk of battery failure; hence, suppressing the TS up to 180 °C is critical to enhancing the cell's safety. In this article, we deposited thin-film coatings (less than 10 nm) of aluminum oxide by atomic layer deposition (ALD) on three different types of separator membranes. The deposition conditions and the plasma pretreatment were optimized to decrease the number of ALD cycles necessary to suppress TS without hindering the battery performance for all of the studied separators. A dependency on the separator composition and porosity was found. After 100 ALD cycles, the thermal shrinkage of a 15 μm thick polyethylene membrane with 50% porosity was measured to be below 1% at 180 °C, with ionic conductivity >1 mS/cm. Full battery cycling with NMC532 cathodes demonstrates no hindrance to the battery's rate capability or the capacity retention rate compared to that of bare membranes during the first 100 cycles. These results display the potential of separators functionalized by ALD to enhance battery safety and improve battery performance without increasing the separator thickness and hence preserving excellent volumetric energy.

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Soiling is a serious problem for asset managers since it reduces the power output of solar modules and the costs of maintenance adversely affects the return on investment. Hydrophobic, anti-soiling coatings offer a potential solution to this problem. However, module cleaning can cause damage to the coatings through abrasion. Abrasion resistance tests have been carried out on candidate anti-soiling coatings with differing chemistry, cured and deposited at different conditions. In this work, we have studied the effects of linear abrasion and washability to assess the susceptibility of anti-soiling coatings to abrasion damage. Preliminary results indicate that great care must be taken over the choice of cleaning materials used. The results also confirm that rigorous laboratory testing of coatings is necessary before they are deployed at scale in the field for solar applications.

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