“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.
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
Food waste and electronic waste are two aspects of the waste stream that present a multitude of challenges for human society. Now a team of scientists led by the Nanyang Technological University (NTU), Singapore has developed a way to use food waste–specifically orange peels–to recover precious metals from spent lithium-ion batteries for reuse in the creation of new batteries.
‘An estimated 1.3 billion tonnes of food waste and 50 million tonnes of e-waste are generated globally each year.
Spent batteries are conventionally treated with extreme heat (over 500°C) to smelt valuable metals, which emits hazardous toxic gases. Alternative approaches that use strong acid solutions or weaker acid solutions with hydrogen peroxide to extract the metals are being explored, but they still produce secondary pollutants that pose health and safety risks, or rely on hydrogen peroxide which is hazardous and unstable.
Professor Madhavi Srinivasan, co-director of the NTU Singapore-CEA Alliance for Research in Circular Economy (NTU SCARCE) lab, said: “Current industrial recycling processes of e-waste are energy-intensive and emit harmful pollutants and liquid waste, pointing to an urgent need for eco-friendly methods as the amount of e-waste grows. Our team has demonstrated that it is possible to do so with biodegradable substances.”‘
Current industrial processes for recycling batteries involve shredding the batteries and crushing them into a powdery substance. That powdery substance is either smelted at temperatures above 500 degrees Celsius to separate metals or subjected to a chemical leaching technique using a mixture of acids and hydrogen peroxide plus heat. The newly developed process substitutes orange peels instead of the acids and hydrogen peroxide typically used. The researchers oven-dried orange peels, ground them to powder, and mixed them with citric acid, a weak acid found in citrus fruits.
‘Asst Prof Tay explained: “The key lies in the cellulose found in orange peel, which is converted into sugars under heat during the extraction process. These sugars enhance the recovery of metals from battery waste. Naturally-occurring antioxidants found in orange peel, such as flavonoids and phenolic acids, could have contributed to this enhancement as well.”
Importantly, solid residues generated from this process were found to be non-toxic, suggesting that this method is environmentally sound, he added.’
The researchers were further able to use metals recovered via this process to assemble new lithium-ion batteries which displayed a charge-capacity similar to commercially available batteries. The team is hoping to further optimize the batteries they can produce in this fashion and extend their “waste-to-resource” approach to other cellulose-rich fruit and vegetable waste and other lithium-ion battery types.
“Repurposing of Fruit Peel Waste as a Green Reductant for Recycling of Spent Lithium-Ion Batteries” by Zhuoran Wu, Tanto Soh, Jun Jie Chan, Shize Meng, Daniel Meyer, Madhavi Srinivasan and Chor Yong Tay, 9 July 2020, Environmental Science & Technology. DOI: 10.1021/acs.est.0c02873
‘A typical recycling process converts large quantities of items made of a single material into more of the same. However, this approach isn’t feasible for old electronic devices, or “e-waste,” because they contain small amounts of many different materials that cannot be readily separated. Now, in ACS Omega, researchers report a selective, small-scale microrecycling strategy, which they use to convert old printed circuit boards and monitor components into a new type of strong metal coating…
Based on the properties of copper and silica compounds, Veena Sahajwalla and Rumana Hossain suspected that, after extracting them from e-waste, they could combine them to create a durable new hybrid material ideal for protecting metal surfaces.
To do so, the researchers first heated glass and plastic powder from old computer monitors to 2,732 F, generating silicon carbide nanowires. They then combined the nanowires with ground-up circuit boards, put the mix on a steel substrate then heated it up again. This time the thermal transformation temperature selected was 1,832 F, melting the copper to form a silicon-carbide enriched hybrid layer atop the steel. Microscope images revealed that, when struck with a nanoscale indenter, the hybrid layer remained firmly affixed to the steel, without cracking or chipping. It also increased the steel’s hardness by 125%. The team refers to this targeted, selective microrecycling process as “material microsurgery,” and say that it has the potential to transform e-waste into advanced new surface coatings without the use of expensive raw materials.’
Rumana Hossain, Veena Sahajwalla. Material Microsurgery: Selective Synthesis of Materials via High-Temperature Chemistry for Microrecycling of Electronic Waste. ACS Omega, 2020; 5 (28): 17062 DOI: 10.1021/acsomega.0c00485
In the March 29, 2019 edition of Resource Recycling, Jared Paben reported that researchers at the Vellore Institute of Technology in India found they could use granules of high-impact polystyrene from scrap electronics as a replacement for sand in self-compacting concrete. They also studied using fly ash from a power plant as a replacement for cement. They found HIPS and fly ash could be used at levels of up to 30 percent without significantly reducing strength, according to their paper, which was published in February in the journal Buildings. Self-compacting lightweight concrete is generally used on long-span bridges, the paper noted.
“Around 7% of the world’s gold is inside e-scrap, of which less than one-third is currently salvaged, according to project leader Professor Jason Love. One tonne of gold ore contains around up to 5 grams of pure gold. However, a tonne of discarded mobile phones easily holds 300 grams of the valuable metal, Love says. The chemical reagent pioneered by in Edinburgh effectively recovers ‘a very high purity of gold’ from various types of discarded electronics. First, the researchers place the printed circuit boards in a mild acid to dissolve metallic parts. An oily liquid containing the new reagent is then added, which allows gold to be extracted selectively from the complex mixture of metals found inside electronics. Professor Love explains that, normally, one molecule of reagent binds directly to a metal molecule. The innovative compound uses a different type of chemistry and can bind to clusters of gold molecules instead of just one. ‘This means you can use a lot less of it to recover the same amount of gold,’ he says.”
The researchers hope to find ways to recover other metals, including valuable (e.g. palladium, platinum, and neodymium), common (e.g. copper and tin), and toxic (e.g. lead and cadmium) metals. Similarly, they are interested in exploring chemical means to more effectively recover plastics from electronic scrap.
With so much positive potential, what could possibly be the downsides of 3D printing? While negative impacts might not be immediately obvious, sustainability advocates must always consider all potential impacts of a technology, product, or action, both positive and negative. The following resources are a good start for considering the often overlooked potential negative impacts of 3D printing.
The Health Effects of 3D Printing. This October 2016 article from American Libraries Magazine discusses exposure to ultrafine particles (UFPs), volatile organic compounds (VOCs), and the risks of bacterial growth in small fissures found within 3D printed objects. The authors provide some very basic tips for reducing risks to patrons and library staff members.
3-D printing: A Boon or Bane? Though a bit dated, this article by Robert Olson, a senior fellow at the Institute for Alternative Futures in Alexandria, VA, in the November/December 2013 issue of the Environmental Forum (the policy journal of the Environmental Law Institute) does a good job of outlining some of the issues that need to be considered when assessing the impacts or appropriateness of this technology. “How efficient are these technologies in the use of materials and energy? What materials are used and what are the worker exposure and environmental impacts? Does the design of printed objects reduce end-of-life options? Does more localized production reduce the carbon footprint? And will simplicity and ubiquity cause us to overprint things, just as we do with paper?“
The dark side of 3D printing: 10 things to watch. This 2014 article by Lyndsey Gilpin for Tech Republic concisely outlines ten potential negative impacts, such as the reliance on plastics, including some that may not have occurred to you, such as IP and licensing issues, bioethics, and national security. Note the mention of 3D printed guns, which have been in the news a fair amount during 2018.
3-D printer emissions raise concerns and prompt controls. This March 26, 2018 article by Janet Pelley in Chemical & Engineering News focuses on potential negative health impacts of inhaling VOCs and plastic particles. “Although the government has set workplace standards for a few of the VOCs released by 3-D printers, these are for healthy working-age adults in industrial settings such as tire or plastic manufacturing plants: None of the compounds is regulated in homes or libraries where 3-D printers might be used by sensitive populations such as children. Furthermore, researchers don’t know the identity of most of the compounds emitted by printers. “Scientists know that particles and VOCs are bad for health, but they don’t have enough information to create a regulatory standard for 3-D printers,” says Marina E. Vance, an environmental engineer at the University of Colorado, Boulder. What’s more, data from early studies of 3-D printer emissions are difficult to use in developing standards because of variability in the test conditions, says Rodney J. Weber, an aerosol chemist at Georgia Institute of Technology. Two years ago, UL, an independent safety certification company, established an advisory board and began funding research projects to answer basic questions about the amounts and types of compounds in 3-D printer emissions, what levels are safe, and how to minimize exposures, says Marilyn S. Black, a vice president at UL. The company is working to create a consistent testing and evaluation method so that researchers will be able to compare data across different labs. ‘By this fall we will put out an ANSI [American National Standards Institute] standard for measuring particles and VOCs for everyone to use,” she says. See the UL Additive Manufacturing pages“, specifically the “library” section for their currently available safety publications.
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!
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.
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.
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.”
As Paben reports, researchers from Sandia National Laboratories have developed a method to use ultrasonic waves, coupled with surfactants, to cheaply and efficiently recover gold from scrap electronics. Their experiments involved application of two different surfactants to the surface of a cell phone SIM card, which was then submerged in water. Ultrasonic waves were applied, which imploded micro-bubbles on the SIM card’s surface. Upon collapse of these micro-bubbles, micro-jets ejected gold nanoparticles from the card’s surface, and the nanoparticles were captured and stabilized by the surfactants.