“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.
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.
Learn more:
“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
On Thursday, January 23, 2020, the US EPA Sustainable Materials Management (SMM) Web Academy will present Safe Packaging and Transportation of Lithium Batteries for Recycling: What You Need to Know. The speaker will be Jordan Rivera of the US Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA).
From the SMM web pages:
“Lithium batteries are key to our modern connected world, from our cellphones and computers to our cars (and not just electric cars) and have an increasing role in storing electricity for the electric grid. But, used lithium batteries aren’t exactly like the used alkaline or lead acid batteries that many are used to working with. Because of the battery’s level of charge and the materials that are inside of it, special preparation is needed when shipping these batteries to a refurbisher or recycler. On this webinar participants will learn how to prevent, reduce or eliminate risks of fire or explosions from the improper packaging, marking, labeling, or recycling of lithium batteries.
This SMM webinar will be hosted by the U.S. Environmental Protection Agency and led by a subject matter expert from the Hazardous Materials Safety Assistance Team under the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA). The webinar will focus on the safe transportation of lithium batteries for recycling and the applicable regulations that must be followed by battery shippers. It is designed for individuals in the battery recycling industry who need a working knowledge of the regulations, or who provide training to their employees on the applicable regulations. They will include an overview on the latest regulatory requirements on proper lithium battery packaging, marking, and labeling and as well as a basic understanding of how to apply the Hazardous Materials Regulations.”
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.
