“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.
As reported on Phys.org, researchers from the National University of Singapore have created a 3D printed prototype of a shoe insole that evaporates sweat faster than normal and uses the harvested moisture to generate energy:
“In our new invention, we created a novel film that is extremely effective in evaporating sweat from our skin and then absorbing the moisture from sweat. We also take this one step further—by converting the moisture from sweat into energy that could be used to power small wearable devices,” explained research team leader Assistant Professor Tan Swee Ching, who is from the NUS Department of Material Science and Engineering.
The main components of the novel thin film are two hygroscopic chemicals—cobalt chloride and ethanolamine. Besides being extremely moisture-absorbent, this film can rapidly release water when exposed to sunlight, and it can be ‘regenerated’ and reused for more than 100 times.
To make full use of the absorbed sweat, the NUS team has also designed a wearable energy harvesting device comprising eight electrochemical cells (ECs), using the novel film as the electrolyte. Each EC can generate about 0.57 volts of electricity upon absorbing moisture. The overall energy harvested by the device is sufficient to power a light-emitting diode. This proof-of-concept demonstration illustrates the potential of battery-less wearables powered using human sweat.”
This prototype is certainly interesting and has obvious potential for improving human comfort, confidence, and possibly health. It remains to be seen whether commercialization of the technology will be feasible and whether researchers develop effective ways to recycle the product at the end of its useful life. Conventional electronics are already a waste generation challenge, and wearable technology is notoriously difficult to recycle and a potential contaminant in recycling streams. Further, the incorporation of cobalt chloride in this product could prove problematic and detrimental to sustainable design, as continues to be the case for most electronics. Cobalt mining operations have been supported by child labor, so truly sustainable designs will strive to use reclaimed cobalt from the recycling of existing products for the preparation of cobalt compounds for the manufacture of new devices. It could be the case that innovations such as this one might reduce reliance on batteries, and thus reduce overall demand for cobalt, but any cobalt in a product supply chain must be scrutinized. We can only hope that the same innovativeness that leads to prototypes such as this insole can inspire researchers to continuously improve the overall sustainability of product design and end-of-life management.
Learn more:
Xueping Zhang et al, Super-hygroscopic film for wearables with dual functions of expediting sweat evaporation and energy harvesting, Nano Energy (2020). DOI: 10.1016/j.nanoen.2020.104873
Cavusoglu, AH., Chen, X., Gentine, P. et al. Potential for natural evaporation as a reliable renewable energy resource. Nat Commun8, 617 (2017). https://doi.org/10.1038/s41467-017-00581-w
“It’s not easy to make a wind turbine blade. Conventional blades require a lot of labor. They are a sandwich composed of fiberglass, sheets of balsa wood and a chemical called an epoxy thermoset resin. A heat oven is required to give blades the proper shape, strength, smoothness and flexibility to catch the wind and turn the turbine.
The new NREL blade uses most of these components, but bonds them together with a thermoplastic resin that can harden and set the blade’s shape at room temperature. It can also be reclaimed at the end of its life by heating it into a liquid resin that can then be reused to make new blades.
That minimizes the waste problem, which became more difficult in Europe after the European Union banned old blades from being dumped in landfills. The new resin is called Elium, and it’s made by Arkema Inc., a French company with offices in King of Prussia, Pa. Arkema is working with NREL to develop the recyclable blade.”
Testing has also suggested the new blade design could have a greater “damping effect,” meaning there would be reduced vibration in the wind during use, and thus, less of the noise nuisance which has been associated with wind turbines. This may also mean reduced stress on the turbine structure resulting in a longer product life.
While this is certainly a promising development, more research is needed before such blades become available for use. Experts at NREL say years of further testing may be required to assure the new blade design is capable of living up to the industry standard of enduring outdoor elements for about 30 years.
NREL researcher Robynne Murray works on a thermoplastic composite turbine blade at the Composites Manufacturing Education and Technology Facility at NREL’s Flatirons Campus. Photo by Dennis Schroeder, NREL
The Responsible Sourcing Network (RSN), is a project of the nonprofit organization As You Sow, dedicated to ending human rights abuses and forced labor associated with the raw materials found in consumer products. On October 18, 2018, RSN released its Mining the Disclosures 2018: An Investor Guide to Conflict Minerals Reporting in Year Five report, which “analyzes 206 companies’ supply chain due diligence efforts regarding conflict minerals, including tin, tantalum, tungsten, and gold, or 3TG. In the fifth consecutive year of analyzing companies’ conflict minerals compliance and reporting, the report shows that a large number of the companies’ scores stayed flat or decreased.”
According to RSN, “The technology sector outperformed all others, while laggard industries included integrated oil & gas, steel, business services, and building materials. Innovative companies showed constant improvements, including increased participation in on-the-ground initiatives, proactive risk assessments, and comprehensive risk mitigation measures. However, compared to 2017, a majority of companies’ scores that reflect alignment with the OECD’S Conflict Minerals Guidance declined. The results show a global lack of desire to improve due diligence practices over the last few years.”
“Conflict minerals” include tin, tantalum, tungsten and gold (aka 3TG). They are so called because these minerals are often sourced from the Democratic Republic of Congo (DRC), which is one of the most mineral-rich countries in the world, and in recent years, unfortunately also one of the most war-torn. Militant groups controlling mines have used violence, including murder, torture, rape and other sexual violence, forced labor and use of child soldiers, in their control of the populace to further their profit from sale of these minerals and their war efforts. Conflict minerals are used in a wide variety of electronic devices, and are also found in a variety of other products, including jewelry, dental products, tools, biocides, ammunition, medical devices, and others. For more information, see https://www.globalwitness.org/en/campaigns/conflict-minerals/ and https://en.wikipedia.org/wiki/Conflict_resource#Conflict_minerals.
Section 1502 of the Dodd-Frank Wall Street Reform and Consumer Protection Action, passed in 2010 and implemented starting in 2012 by the Securities and Exchange Commission, requires that all companies publicly traded in the the US with products containing any of the four conflict minerals report on the source of the minerals in their supply chain. This required transparency has not eliminated human rights issues associated with conflict mineral sourcing, but it has demonstrably improved conditions for Congolese miners. Before passage of the law, the UN reported that nearly every mine in Congo was controlled by armed groups. As of 2016, the independent research institute, International Peace Information Service (IPIS) found that 79% of “3T” miners surveyed in eastern Congo were working in mines where no armed group involvement had been reported. (See https://enoughproject.org/special-topics/progress-and-challenges-conflict-minerals-facts-dodd-frank-1502).
RSN cites the Trump administration’s “contempt for regulations” and threats made last year to “suspend Section 1502 of the Dodd-Frank Act” as part of the reason for the decline in corporate due diligence related to conflict minerals sourcing. “The disregard of corporate responsibility for conflict minerals during the Trump administration is concerning,” said Raphaël Deberdt, author of the Mining the Disclosures 2018 report. “The increasing neglect of the conflict minerals legislation from some companies over the past few years has been a source of human rights abuses in the Democratic Republic of the Congo. And these abuses extend beyond the 3TG sphere.”
According the RSN press release: ‘Companies involved in mineral supply chains — from mines to retailers — now face additional challenges that must be integrated into corporate risk mitigation frameworks. The increasing importance of cobalt, lithium, and nickel in the automotive and technology sectors should trigger red flags in compliance departments in a broader risk context, including environmental degradation, organizational health and safety, human rights, and community impacts. Similarly, the upcoming EU regulation will necessitate increased due diligence from importers of 3TG, not only from the Congo region, but from all conflict-affected and high-risks areas. “The results of this year’s report demonstrate the need for an increase in regulatory enforcement and investor engagement that urge companies to undertake proactive due diligence efforts,” said Patricia Jurewicz, vice president of Responsible Sourcing Network. “These programs must continuously improve to address and mitigate the evolving material risks associated with conflict mineral supply chains.” ‘
RSN further asserted that “leading companies” such as Intel, Microsoft, Apple, Qualcomm, Ford, Royal Philips, and HP “prove that taking a due diligence approach to reduce harmful impacts on the communities producing the raw materials in our electronics is an achievable and beneficial business model.”
As electronics become more ubiquitous each day, the integration of smaller electronic components into ever more products continues, and renewable energy becomes an increasingly popular strategy for addressing climate change, the ability to store and supply power efficiently and safely is all the more important. So it’s no surprise that batteries have been a hot topic in the news for the past month or so. Let’s take a moment to consider some of the highlights of recent battery-related news.
We may as well start with the well-written piece by Geoffrey A. Fowler, the Washington Post’s technology columnist, published today (9/12/18): “The problem with recycling our old tech gadgets: They explode.” This is a good article about how design choices to make electronics thinner and more portable make the recycling of electronics more difficult and dangerous. Specifically because lithium-ion batteries are being incorporated into more products and smaller products, often without an easy–or any–way to remove those batteries. This isn’t just problematic for for extending the useful life of products. The trend makes the recycling of electronics increasingly risky while simultaneously making the economic feasibility of such efforts diminish. Recyclers need more time, special equipment, and training for proper handling, and they are at greater risk of damages caused by fires. As Fowler explains: “For all their benefits at making our devices slim, powerful and easy to recharge, lithium-ion batteries have some big costs. They contain Cobalt, often mined in inhumane circumstances in places like the Congo. And when crushed, punctured, ripped or dropped, lithium-ion batteries can produce what the industry euphemistically calls a “thermal event.” It happens because these batteries short circuit when the super-thin separator between their positive and negative parts gets breached. Remember Samsung’s exploding Note 7 smartphone? That was a lithium-ion thermal event.”
Fowler visits Cascade Asset Management, an electronics scrap processor in Madison, WI, to observe the process of removing a battery from an old iPad before the device can be sent through the shredder for recycling. My take away from this article: products need to be designed not only with sleek aesthetics and portability in mind, but also the ability to easily and safely upgrade, repair, and maintain them during their useful life and then to easily and safely reclaim parts and component materials when they have reached their end of useful life. Fowler concludes “So as a gadget reviewer, let me say this clearly to the tech industry: Give up your thin obsession. We’ll happily take electronics with a little extra junk in the trunk if it means we can easily replace batteries to make them last longer – and feel more confident they won’t end up igniting a recycling inferno.” Do agree with his sentiment? Consider voicing that opinion to the manufacturers of your favorite devices, and if you’re an industrial design student, heed well the lessons you can learn from this article.
As long as we’re on the subject of “thermal events,” consider this interesting research highlighted in this article provided by the American Chemical Society : “These lithium-ion batteries can’t catch fire because they harden on impact.” ‘Lithium-ion batteries commonly used in consumer electronics are notorious for bursting into flame when damaged or improperly packaged. These incidents occasionally have grave consequences, including burns, house fires and at least one plane crash. Inspired by the weird behavior of some liquids that solidify on impact, researchers have developed a practical and inexpensive way to help prevent these fires. They will present their results today at the 256th National Meeting & Exposition of the American Chemical Society (ACS). “In a lithium-ion battery, a thin piece of plastic separates the two electrodes,” Gabriel Veith, Ph.D., says. “If the battery is damaged and the plastic layer fails, the electrodes can come into contact and cause the battery’s liquid electrolyte to catch fire.” To make these batteries safer, some researchers instead use a nonflammable, solid electrolyte. But these solid-state batteries require significant retooling of the current production process, Veith says. As an alternative, his team mixes an additive into the conventional electrolyte to create an impact-resistant electrolyte. It solidifies when hit, preventing the electrodes from touching if the battery is damaged during a fall or crash. If the electrodes don’t touch each other, the battery doesn’t catch fire. Even better, incorporating the additive would require only minor adjustments to the conventional battery manufacturing process…In the future, Veith plans to enhance the system so the part of the battery that’s damaged in a crash would remain solid, while the rest of the battery would go on working. The team is initially aiming for applications such as drone batteries, but they would eventually like to enter the automotive market. They also plan to make a bigger version of the battery, which would be capable of stopping a bullet. That could benefit soldiers, who often carry 20 pounds of body armor and 20 pounds of batteries when they’re on a mission, Veith says. “The battery would function as their armor, and that would lighten the average soldier by about 20 pounds.”
Imagine the day when lithium-ion batteries might be an asset for safety instead of a liability!
Adding powdered silica (in blue container) to the polymer layer (white sheet) that separates electrodes inside a test battery (gold bag) will prevent lithium-ion battery fires. Credit: Gabriel Veith
Writing for the HOBI International blog, Alicia Cotton recently wrote that “Innovation is making lithium-ion batteries increasingly harder to recycle.” The point of her post was that as demand for lithium-ion batteries increase, manufacturers will look to produce them with cheaper materials, adversely impacting the economic incentives for recycling these batteries. ‘According to the Royal Chemistry Society, the cost of cobalt, which is heavily used as a cathode material in all batteries, jumped from $32,500 to $81,000 in just over a year. In response, battery manufacturers have opted to redesign batteries to minimize cobalt. In May, Tesla CEO Elon Musk said the company had all but eliminated cobalt from batteries it uses in automobile and stationary batteries. However, doing so will help keep batteries cheap — as in too cheap to recycle. Without valuable contents recyclers have little incentive to capture used batteries, Kaun said.‘ This is an interesting example of trade-offs and how considerations for sustainability are rarely simple. The use of cobalt in batteries is problematic not just due to the economic cost of the material, but also due to human rights issues related to cobalt sourcing. However, this article points out that as higher value materials are phased out of design, there is a negative impact on the economics of recycling. More work is clearly needed to create recycling incentives for lithium-ion batteries moving forward, as well as developing batteries which depend less on cobalt, and improving the sustainability of the cobalt supply chain.
In another recent post for the HOBI International blog, Cotton writes that a “New Material will Triple Storage Capacity of Lithium-Ion Batteries.” “Together in a joint effort, scientists from the University of Maryland (UMD), U.S. Army Research Lab and the U.S. Department of Energy’s (DOE) have been working hard to improve the storage capacity of lithium-ion batteries. Turns out, the use of extra cobalt was the answer. The scientists believe they can triple the energy density of lithium-ion battery electrodes.” Well, that would make those batteries not only have higher storage capacity, but also create an incentive for recycling them–but then we’re looking at the issues surrounding cobalt sourcing again. What did I say about trade-offs and how sustainable solutions are rarely simple? Sigh.
And, while we’re on the subject of sustainable solutions coming in shades of grey, here’s an example of how context can be important. As someone who advocates for waste reduction, I often talk about the need for more durable, repairable, upgradable goods and a move away from disposability. I certainly like to encourage people to use rechargeable batteries instead of single-use ones where they can. But there are situations in which disposable goods might actually foster sustainability, and yes, this is even true for batteries. Another recent update from the American Chemical Society discussed “A paper battery powered by bacteria.” Consider remote areas of the world where access to electricity is a luxury, or situation in which a natural disaster or other emergency has occurred leaving an area without access to power. Think about medical devices that would be needed to help victims of a disaster, or just be part of everyday medical support in remote areas. Paper is desirable for biosensors due to its flexibility, portability, high surface area, and inexpensive nature. “Choi and his colleagues at the State University of New York, Binghamton made a paper battery by printing thin layers of metals and other materials onto a paper surface. Then, they placed freeze-dried “exoelectrogens” on the paper. Exoelectrogens are a special type of bacteria that can transfer electrons outside of their cells. The electrons, which are generated when the bacteria make energy for themselves, pass through the cell membrane. They can then make contact with external electrodes and power the battery. To activate the battery, the researchers added water or saliva. Within a couple of minutes, the liquid revived the bacteria, which produced enough electrons to power a light-emitting diode and a calculator…The paper battery, which can be used once and then thrown away, currently has a shelf-life of about four months. Choi is working on conditions to improve the survival and performance of the freeze-dried bacteria, enabling a longer shelf life.“In a related article by Jason Deign for Greentech Media, Choi noted that in these low-power, low-cost situations, the paper battery could be used and then biodegrade without special treatment. Further reporting on this innovation is available in the IEEE Spectrum.
Researchers harnessed bacteria to power these paper batteries. Credit: Seokheun Choi.
Now that you’ve read about all these innovations and the need for further innovations, you may be thinking, “Can someone please just tell what a lithium-ion battery is, the basics of how they work, and why we use them if there are so many problematic issues?!?!” Don’t worry–a recent post by Arthur Shi on the iFixit blog provides a nice overview with some links to more in-depth explanations if you’re interested.
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.
Researchers propose a new method for nanomaterial selection that incorporates environmental and functional performance, as well as cost. Credit: Steve Geringer.
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.”
