“The idea is to simplify how solar energy is harvested and stored,” says Michael De Volder, a mechanical engineer at the University of Cambridge who led the work. If the team can improve the efficiency and lifetime of the hybrid device, its cost will likely be lower than combining solar cells and batteries. “For the price of a battery, you get both functionalities,” he says.
This low cost could make it suitable for off-grid uses and for regions of the world that lack access to affordable energy.
The workhorse of the new light-rechargeable battery is a cathode made of vanadium pentoxide nanofibers. The material stores lithium ions and also harvests light to generate paired electrons and positive charges, or holes. The researchers mixed the nanofibers with poly(3-hexylthiophene-2,5-diyl) (P3HT) that blocks the movement of holes, and graphene oxide that aids electron transport.”
A glass window on the cathode side of a coin cell allows light to reach the nanofibers. This new device is more efficient than previously developed light-rechargeable batteries and can be recharged for over 200 cycles. Though the efficiency of this battery is still too low for practical use, researchers hope to explore alternatives to vanadium pentoxide to improve efficiency.
From the May 1, 2018 edition of Science Daily: “Engineered nanomaterials hold great promise for medicine, electronics, water treatment, and other fields. But when the materials are designed without critical information about environmental impacts at the start of the process, their long-term effects could undermine those advances. A team of researchers hopes to change that.
In a study published in Nature Nanotechnology, Yale researchers outline a strategy to give materials designers the tools they need to make the necessary assessments efficiently and at the beginning of the design process. Engineers traditionally focus on the function and cost of their products. Without the information to consider long-term environmental impacts, though, it is difficult to predict adverse effects. That lack of information means that unintended consequences often go unnoticed until long after the product has been commercialized. This can lead to hastily replacing the material with another that proves to have equally bad, or even worse, effects. Having materials property information at the start of the design process could change that pattern. “As a researcher, if I have limited resources for research and development, I don’t want to spend it on something that’s not going to be viable due to its effects on human health,” said Julie Zimmerman, professor of chemical & environmental engineering and co-senior author of the study. “I want to know now, before I develop that product.” To that end, the researchers have developed a database that serves as a screening tool for environmentally sustainable material selection. It’s a chart that lists nanomaterials and assesses each for properties such as size, shape, and such performance characteristics as toxicity and antimicrobial activity. Mark Falinski, a PhD student and lead author of the study, said this information would allow researchers to weigh the different effects of the material before actually developing it.”
The database created by the research team also allows other researchers to enter information to improve the material selection framework. It includes engineered nanomaterials and conventional alternatives with human health and environmental metrics for all materials.
The research team includes scientists affiliated with Yale University, the University of Illinois at Chicago, City University of Hong Kong, and the University of Pittsburgh.
Read the referenced article in Nature Nanotechnology at https://www.nature.com/articles/s41565-018-0120-4. [Mark M. Falinski, Desiree L. Plata, Shauhrat S. Chopra, Thomas L. Theis, Leanne M. Gilbertson, Julie B. Zimmerman. A framework for sustainable nanomaterial selection and design based on performance, hazard, and economic considerations. Nature Nanotechnology, 2018; DOI: 10.1038/s41565-018-0120-4]
To learn more about the potential environmental and health impacts of nanotechnology, see the following:
Watch for Nanotechnology Environmental Health and Safety: Risks, Regulation, and Management, Third Edition, edited by Matthew Hull and Diana Bowman, due out in August 2018. See https://www.elsevier.com/books/nanotechnology-environmental-health-and-safety/hull/978-0-12-813588-4. This book “includes real-world case studies, wherever practical, to illustrate specific issues and scenarios encountered by stakeholders positioned on the frontlines of nanotechnology-enabled industries. Each case study will appeal and resonate with laboratory scientists, business leaders, regulators, service providers and postgraduate researchers.”