The Kynix Blog - Battery

Researchers have developed a prototype of a next-generation lithium-sulphur battery which takes its inspiration in part from the cells lining the human intestine. The batteries, if commercially developed, would have five times the energy density of the lithium-ion batteries used in smartphones and other electronics.The new design, by researchers from the University of Cambridge, overcomes one of the key technical problems hindering the commercial development of lithium-sulphur batteries, by preventing the degradation of the battery caused by the loss of material within it. The results are reported in the journal Advanced Functional Materials.Working with collaborators at the Beijing Institute of Technology, the Cambridge researchers based in Dr Vasant Kumar's team in the Department of Materials Science and Metallurgy developed and tested a lightweight nanostructured material which resembles villi, the finger-like protrusions which line the small intestine. In the human body, villi are used to absorb the products of digestion and increase the surface area over which this process can take place.In the new lithium-sulphur battery, a layer of material with a villi-like structure, made from tiny zinc oxide wires, is placed on the surface of one of the battery's electrodes. This can trap fragments of the active material when they break off, keeping them electrochemically accessible and allowing the material to be reused."It's a tiny thing, this layer, but it's important," said study co-author Dr Paul Coxon from Cambridge's Department of Materials Science and Metallurgy. "This gets us a long way through the bottleneck which is preventing the development of better batteries."A typical lithium-ion battery is made of three separate components: an anode (negative electrode), a cathode (positive electrode) and an electrolyte in the middle. The most common materials for the anode and cathode are graphite and lithium cobalt oxide respectively, which both have layered structures. Positively-charged lithium ions move back and forth from the cathode, through the electrolyte and into the anode.The crystal structure of the electrode materials determines how much energy can be squeezed into the battery. For example, due to the atomic structure of carbon, each carbon atom can take on six lithium ions, limiting the maximum capacity of the battery.Sulphur and lithium react differently, via a multi-electron transfer mechanism meaning that elemental sulphur can offer a much higher theoretical capacity, resulting in a lithium-sulphur battery with much higher energy density. However, when the battery discharges, the lithium and sulphur interact and the ring-like sulphur molecules transform into chain-like structures, known as a poly-sulphides. As the battery undergoes several charge-discharge cycles, bits of the poly-sulphide can go into the electrolyte, so that over time the battery gradually loses active material.The Cambridge researchers have created a functional layer which lies on top of the cathode and fixes the active material to a conductive framework so the active material can be reused. The layer is made up of tiny, one-dimensional zinc oxide nanowires grown on a scaffold. The concept was trialled using commercially-available nickel foam for support. After successful results, the foam was replaced by a lightweight carbon fibre mat to reduce the battery's overall weight."Changing from stiff nickel foam to flexible carbon fibre mat makes the layer mimic the way small intestine works even further," said study co-author Dr Yingjun Liu.This functional layer, like the intestinal villi it resembles, has a very high surface area. The material has a very strong chemical bond with the poly-sulphides, allowing the active material to be used for longer, greatly increasing the lifespan of the battery."This is the first time a chemically functional layer with a well-organised nano-architecture has been proposed to trap and reuse the dissolved active materials during battery charging and discharging," said the study's lead author Teng Zhao, a PhD student from the Department of Materials Science & Metallurgy. "By taking our inspiration from the natural world, we were able to come up with a solution that we hope will accelerate the development of next-generation batteries."For the time being, the device is a proof of principle, so commercially-available lithium-sulphur batteries are still some years away. Additionally, while the number of times the battery can be charged and discharged has been improved, it is still not able to go through as many charge cycles as a lithium-ion battery. However, since a lithium-sulphur battery does not need to be charged as often as a lithium-ion battery, it may be the case that the increase in energy density cancels out the lower total number of charge-discharge cycles."This is a way of getting around one of those awkward little problems that affects all of us," said Coxon. "We're all tied in to our electronic devices - ultimately, we're just trying to make those devices work better, hopefully making our lives a little bit nicer."Reference:KY605-ML-621S/ZTNKY605-MS412FE-FL26EKY605-MS518SE-FL35E

A molecule that transports oxygen in blood could be key to developing the next generation of batteries, and in a way that's environmentally friendly.Lithium-oxygen (Li-O2) batteries have emerged in recent years as a possible successor to lithium-ion batteries—the industry standard for consumer electronics—due to their potential for holding a charge for a very long time. Electronic devices would go for weeks without charging, for instance; electric cars could travel four to five times longer than the current standard.But before this could happen, researchers need to make the Li-O2 batteries efficient enough for commercial application and prevent the formation of lithium peroxide, a solid precipitate that covers the surface of the batteries' oxygen electrodes. One obstacle is finding a catalyst that efficiently facilitates a process known as oxygen evolution reaction, in which lithium oxide products decompose back into lithium ions and oxygen gas.The Yale lab of Andre Taylor, associate professor of chemical and environmental engineering, has identified a molecule known as heme that could function as a better catalyst. The researchers demonstrated that the heme molecule improved the Li-O2 cell function by lowering the amount of energy required to improve the battery's charge/discharge cycle times.The results appear Oct. 19 in Nature Communications. The lead author is Won-Hee Ryu, a former postdoctoral researcher in Taylor's lab, who is now an assistant professor of chemical and biological engineering at Sookmyung Women's University in South Korea.The heme is a molecule that makes up one of the two parts of a hemoglobin, which carries oxygen in the blood of animals. Used in an Li-O2 battery, Ryu explained, the molecule would dissolve into the battery's electrolytes and act as what's known as a redox mediator, which lowers the energy barrier required for the electrochemical reaction to take place."When you breathe in air, the heme molecule absorbs oxygen from the air to your lungs and when you exhale, it transports carbon dioxide back out," Taylor said. "So it has a good binding with oxygen, and we saw this as a way to enhance these promising lithium-air batteries."The researchers added that their discovery could help reduce the amount of animal waste disposal."We're using a biomolecule that traditionally is just wasted," said Taylor. "In the animal products industry, they have to figure out some way to dispose of the blood. Here, we can take the heme molecules from these waste products and use it for renewable energy storage."By using recyclable biowaste as a catalyst material, the technology is both effective and could be preferential in developing green energy applications.Reference:ML-621S/ZTNMS412FE-FL26EMS518SE-FL35E 

 Samsung's recall of 2.5 million Galaxy Note 7 phones after several dozen caught fire and exploded may stem from a subtle manufacturing error, but it highlights the challenge electronics makers face in packing ever more battery power into ever thinner phones, while rushing for faster release dates.Announcing the recall on Sept. 2, Samsung confirmed dozens of cases where Note 7 batteries caught fire or exploded, mostly while charging. It plans a software update that will cap battery recharging at 60 percent capacity to help minimize risks of overheating. But it is urging owners to keep the phones turned off until they can get them replaced, beginning Monday.U.S. safety regulators stepped in Thursday with an official recall, saying Samsung's voluntary efforts were inadequate. Though Samsung promised replacement devices, the U.S. Consumer Product Safety Commission said U.S. customers would be eligible for refunds if they choose. Replacements are expected in stores by next Wednesday.The Note 7 debuted to rave reviews in August thanks to its speed, new software features and—not least—the estimated nine hours it would run between charges. But all that power comes at a price: Users began reporting the phones were catching fire or exploding, in one case incinerating the SUV it had been left in.Aviation authorities in the U.S., Australia and Europe have urged passengers not to use or charge Note 7s while flying and not to put them in checked baggage. On Monday, Canada issued an official recall.Koh Dong-jin, Samsung's mobile president, said in announcing the recall on Sept. 2 that an investigation turned up a "tiny error" in the manufacturing process for the faulty batteries in the Note 7s that was very difficult to identify. The end of the pouch-shaped battery cell had some flaws that increased the chance of stress or overheating, he explained.That kind of manufacturing error is unimaginable for top-notch battery makers with adequate quality controls, said Park Chul Wan, a former director of the next generation battery research center at the state-owned Korea Electronics Technology Institute.Samsung and other experts should search for factors outside the battery cells that could have led to overheating, he said."If Koh's argument is right, that makes Samsung SDI a third-rate company," Park said. "But it does not appear to be a simple battery problem."Time also is a factor in marketing and making the phones.In 2015, Samsung moved up its unveiling of its new Galaxy Note model to August from September, seeking a leg up on Apple's September iPhone upgrades.Before the issue of battery explosions emerged, supplies were not keeping pace with demand for the Note 7.Samsung has not recalled Note 7s sold in China, but the company has refused to say which of its two battery suppliers made the faulty batteries or clarify whose batteries are used in which Note 7 smartphones. The company also refused comment on South Korean media reports that it has stopped using batteries from Samsung SDI, one of its two suppliers, in the Note 7.C.W. Chung, an analyst at Nomura Securities in Seoul, cited SDI officials in estimating that about 70 percent of the batteries for the Galaxy Note 7 smartphones came from SDI.The other 30 percent are thought to have been supplied by Amperex Technology Ltd., a Chinese-based manufacturer that reportedly also is a main supplier of batteries for the iPhone.Problems with lithium batteries have afflicted everything from laptops to Tesla cars to Boeing's 787 jetliner, though having so many lithium-ion battery fires in a short time is unheard of, Park said.The batteries are ubiquitous in consumer electronic devices, favored by manufacturers because they are lightweight and pack much more energy into a small space than other power cells.But storing so much energy in a tiny space, with combustible components separated by ultra-thin walls, makes them susceptible to overheating if exposed to high temperatures, damage or flaws in manufacturing. If the separators fail, a chemical reaction can quickly escalate out of control.That's what happened with the Note 7, Samsung's Koh explained."The flaw in the manufacturing process resulted in the negative electrodes and the positive electrodes coming together," he told reporters in Seoul.It is unclear how Samsung failed to discover the battery problem before launching the Note 7. It confirmed delays in shipments for extra quality tests weeks later, in late August, after photos of charred phones began popping up on social media.South Korean experts suggested Samsung may have been so ambitious with the Note 7's design that it compromised safety."There was no choice but to make the separator (between positive and negative anodes) thin because of the battery capacity," said Lee Sang-yong, a professor at Ulsan National Institute of Science and Technology who worked more than a decade at LG Chem, a leading lithium battery maker. Thicker separators can improve safety but will not necessarily prevent all overheating issues, he said.Doh Chil-Hoon, head of the state-run Korea Electrotechnology Research Institute's battery research division, said that based on the limited information provided by Samsung, he believes the push to increase battery power was part of the problem."Even with a small manufacturing mistake, if there had been enough elements to ensure safety, it would not explode," Doh said. "It is a roundabout way of admitting weak safety."The Note 7 phones have a powerful 3,500 milliampere hour battery, whereas the Galaxy S7 smartphone, which has a slightly smaller body than the Note 7, features a 3,000 mAh battery. So does the Note 5, launched in 2015.Apple does not provide information on the iPhone's battery capacity in milliampere hours. But two research firms that specialize in analyzing tech gadgets and their components said the battery in the iPhone 6S Plus is 2,750mAh. The size of the battery in the newly released iPhone 7 is not yet known.The 3,500 mAh battery in the Samsung Note 7 is "one of the highest, if not the highest, capacity battery we've seen in a phone," said Wayne Lam, an industry analyst at IHS Markit Technology.Lam said he thinks the Note 7 battery problem resulted from weak controls in manufacturing, not a poor or unsafe design.A spokeswoman at iFixit, which publishes repair guides for electronic gadgets, offered a similar view. "We don't think any internal design changes in the Note 7 are responsible for the exploding batteries—more likely just a manufacturing defect," IFixit's Kay-Kay Clapp said in an email.Apple has tweaked hardware and software it developed itself to make iPhones use power more efficiently, while Samsung has increased the capacity of the batteries in its phones.That can be done without increasing size by adjusting components or changing the production process, Lam said."You have two different trajectories, with Samsung packing in more energy density, versus Apple trying to trim it down by optimizing everything else," he said, adding that the two rivals are "constantly locked in this arms race of improving and one-upping."While Apple and Samsung are using built-in batteries for their premium phones, LG Electronics, Samsung's smaller South Korean rival, has opted for a replaceable, 3,200 mAh capacity battery for its new premium, jumbo screen smartphone, the V20.LG chose to make the phone thinner and allow customers to extend battery life by swapping out batteries."The security of the battery isn't directly related to whether the battery is replaceable or not," Cho Joon-ho, head of LG's mobile business, told reporters. "But we make efforts to secure safety with quality controlling tests beforehand."  

Chemists at the University of Waterloo have developed a long-lasting zinc-ion battery that costs half the price of current lithium-ion batteries and could help enable communities to shift away from traditional power plants and into renewable solar and wind energy production.Professor Linda Nazar and her colleagues from the Faculty of Science at Waterloo made the important discovery, which appears in the journal, Nature Energy.The battery uses safe, non-flammable, non-toxic materials and a ph-neutral, water-based salt. It consists of a water-based electrolyte, a pillared vanadium oxide positive electrode and an inexpensive metallic zinc negative electrode. The battery generates electricity through a reversible process called intercalation, where positively-charged zinc ions are oxidized from the zinc metal negative electrode, travel through the electrolyte and insert between the layers of vanadium oxide nanosheets in the positive electrode. This drives the flow of electrons in the external circuit, creating an electrical current. The reverse process occurs on charge.The cell represents the first demonstration of zinc ion intercalation in a solid state material that satisfies four vital criteria: high reversibility, rate and capacity and no zinc dendrite formation. It provides more than 1,000 cycles with 80 per cent capacity retention and an estimated energy density of 450 watt-hours per litre. Lithium-ion batteries also operate by intercalation—of lithium ions—but they typically use expensive, flammable, organic electrolytes."The worldwide demand for sustainable energy has triggered a search for a reliable, low-cost way to store it," said Nazar, a Canada Research Chair in Solid State Energy Materials and a University Research Professor in the Department of Chemistry. "The aqueous zinc-ion battery we've developed is ideal for this type of application because it's relatively inexpensive and it's inherently safe."The global market for energy storage is expected to grow to $25 billion in the next 10 years. The bonus for manufacturers is they can produce this zinc battery at low cost because its fabrication does not require special conditions, such as ultra-low humidity or the handling of flammable materials needed for lithium ion batteries."The focus used to be on minimizing size and weight for the portable electronics market and cars," said Dipan Kundu, a postdoctoral fellow in Nazar's lab and the paper's first author. "Grid storage needs a different kind of battery and that's given us license to look into different materials."Water in the electrolyte not only facilitates the movement of zinc ions, it also swells the space between the sheets, like tiers of a wedding cake, giving the zinc just enough room to enter and leave the positive structure as the battery cycles. The electrode material's nano-scale dimensions and the battery's high-conductivity aqueous electrolyte also improve its cycling life and response times.Together with researchers at the Joint Center for Energy Storage Research in the U.S., Nazar's team is also investigating multivalent ion intercalation batteries based on Mg2+ in non-aqueous electrolytes. They were the first to report highly reversible Mg cycling in the TiS2 thiospinel and layered sulfides, which represent the first new highly functional Mg insertion materials reported in more than 15 years. Their papers appeared in Energy & Environmental Science and ACS Energy Letters earlier this year. 

Harvard researchers have identified a whole new class of high-performing organic molecules, inspired by vitamin B2, that can safely store electricity from intermittent energy sources like solar and wind power in large batteries.The development builds on previous work in which the team developed a high-capacity flow battery rechargreable that stored energy in organic molecules called quinones and a food additive called ferrocyanide. That advance was a game-changer, delivering the first high-performance, non-flammable, non-toxic, non-corrosive, and low-cost chemicals that could enable large-scale, inexpensive electricity storage.While the versatile quinones show great promise for flow batteries, Harvard researchers continued to explore other organic molecules in pursuit of even better performance. But finding that same versatility in other organic systems has been challenging."Now, after considering about a million different quinones, we have developed a new class of battery electrolyte material that expands the possibilities of what we can do," said Kaixiang Lin, a Ph.D. student at Harvard and first author of the paper. "Its simple synthesis means it should be manufacturable on a large scale at a very low cost, which is an important goal of this project."Flow batteries store energy in solutions in external tanks—the bigger the tanks, the more energy they store. In 2014, Michael J. Aziz, the Gene and Tracy Sykes Professor of Materials and Energy Technologies at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), Roy Gordon, the Thomas Dudley Cabot Professor of Chemistry and Professor of Materials Science, Alán Aspuru-Guzik, Professor of Chemistry and their team at Harvard replaced metal ions used as conventional battery electrolyte materials in acidic electrolytes with quinones, molecules that store energy in plants and animals. In 2015, they developed a quinone that could work in alkaline solutions alongside a common food additive.In this most recent research, the team found inspiration in vitamin B2, which helps to store energy from food in the body. The key difference between B2 and quinones is that nitrogen atoms, instead of oxygen atoms, are involved in picking up and giving off electrons.."They have high stability and solubility and provide high battery voltage and storage capacity. Because vitamins are remarkably easy to make, this molecule could be manufactured on a large scale at a very low cost.""We designed these molecules to suit the needs of our battery, but really it was nature that hinted at this way to store energy," said Gordon, co-senior author of the paper. "Nature came up with similar molecules that are very important in storing energy in our bodies."The team will continue to explore quinones, as well as this new universe of molecules, in pursuit of a high-performing, long-lasting and inexpensive flow battery. 

Wearables and IoT gadgets, featuring smart functions in much smaller form factors, pose battery challenges and headaches by their small size. ARM has made moves that might change the story of battery life of many wearables and other small devices, with its recent acquisition of two companies. Reports on Friday about ARM focused on its having acquired two low-power wireless communications companies.The technology could extend the battery life of Internet of Things (IoT) devices, including wearables, by up to 60 per cent (compared to radio hardware that operates at 1.2 volts), said Daily Telegraph technology reporter Sophie Curtis. ("ARM claims that the Cordio radio technology system, operating below one volt, can extend battery life by 60 per cent, compared to radio hardware that operates at 1.2 volts," said the report. The two companies, Sunrise Micro Devices and Wicentric, said Curtis, will form the basis of its new Cordio portfolio. The result could brighten the picture for the development of low-power wireless communications for power-hungry devices.Aatif Sulleyman in TrustedReviews similarly observed how "Much of the power consumed by wearables is used up while communicating with other devices, such as smartphones. ARM wants to make this process less draining."ARM describes Cordio as a family of standards-based, low-power radio IP solutions. Each Cordio solution includes a pre-qualified, self-contained radio block, related link layer firmware, stack and profiles. It also carries guidelines for design, test, integration, qualification, and application development. ARM said semiconductor companies can benefit by having access to sub-volt radio solutions.Sunrise Micro Devices, said ARM, focuses on radio IP solutions and provides "a pre-qualified, self-contained radio block and related firmware to simplify radio deployment." Central to SMD radios is native sub-one volt operation. "Operating below one volt enables the radio to run much longer on batteries or harvested energy." Wicentric focuses on providing Bluetooth Smart software solutions. Curtis said Wicentric's Bluetooth Smart software solutions will run on the sub-one volt radios and help ease power consumption too.Paul Buckley in EE/Times said, "ARM is keen to make the Cordio solutions efficient enough to be powered using energy harvesting and sees SMD's sub-one volt Bluetooth radio IP as a vital ingredient in the design armory."The Cordio radio IP is being promoted as a fully integrated platform which includes transceiver, baseband, and link layer (LL) subsystem including firmware. The subsystem, said ARM, provides an "energy efficient, timing-independent interface to the host processor, enabling easy implementation of the stack and application layers. In addition, the subsystem intelligently controls the sleep and wake-up times of the host processor leading to lower system-wide power consumption."ARM said that "Core to all Cordio radio hardware is native sub-volt operation. Operating below 1 Volt enables the radio to 'sip' energy from a battery, thus greatly extending the device's life. In addition, it makes it easier to run without batteries by using energy harvesting technologies."In the bigger picture, "ARM is gradually building up a suite of IoT-focused solutions," said Buckley, "that address key stumbling blocks associated with developing commercially viable IoT products."