batteries

A solid electrolyte gives lithium-sulfur batteries ludicrous endurance

batteries, chemistry, electrolyte, lithium battery, lithium-sulfur battery, Science, solid electrolyte / Kris Guyer / January 17, 2025

Sulfur can store a lot more lithium but is problematically reactive in batteries.

If you weren’t aware, sulfur is pretty abundant. Credit: P_Wei

Lithium may be the key component in most modern batteries, but it doesn’t make up the bulk of the material used in them. Instead, much of the material is in the electrodes, where the lithium gets stored when the battery isn’t charging or discharging. So one way to make lighter and more compact lithium-ion batteries is to find electrode materials that can store more lithium. That’s one of the reasons that recent generations of batteries are starting to incorporate silicon into the electrode materials.

There are materials that can store even more lithium than silicon; a notable example is sulfur. But sulfur has a tendency to react with itself, producing ions that can float off into the electrolyte. Plus, like any electrode material, it tends to expand in proportion to the amount of lithium that gets stored, which can create physical strains on the battery’s structure. So while it has been easy to make lithium-sulfur batteries, their performance has tended to degrade rapidly.

But this week, researchers described a lithium-sulfur battery that still has over 80 percent of its original capacity after 25,000 charge/discharge cycles. All it took was a solid electrolyte that was more reactive than the sulfur itself.

When lithium meets sulfur…

Sulfur is an attractive battery material. It’s abundant and cheap, and sulfur atoms are relatively lightweight compared to many of the other materials used in battery electrodes. Sodium-sulfur batteries, which rely on two very cheap raw materials, have already been developed, although they only work at temperatures high enough to melt both of these components. Lithium-sulfur batteries, by contrast, could operate more or less the same way that current lithium-ion batteries do.

With a few major exceptions, that is. One is that the elemental sulfur used as an electrode is a very poor conductor of electricity, so it has to be dispersed within a mesh of conductive material. (You can contrast that with graphite, which both stores lithium and conducts electricity relatively well, thanks to being composed of countless sheets of graphene.) Lithium is stored there as Li₂S, which occupies substantially more space than the elemental sulfur it’s replacing.

Both of these issues, however, can be solved with careful engineering of the battery’s structure. A more severe problem comes from the properties of the lithium-sulfur reactions that occur at the electrode. Elemental sulfur exists as an eight-atom ring, and the reactions with lithium are slow enough that semi-stable intermediates with smaller chains of sulfur end up forming. Unfortunately, these tend to be soluble in most electrolytes, allowing them to travel to the opposite electrode and participate in chemical reactions there.

This process essentially discharges the battery without allowing the electrons to be put to use. And it gradually leaves the electrode’s sulfur unavailable for participating in future charge/discharge cycles. The net result is that early generations of the technology would discharge themselves while sitting unused and would only survive a few hundred cycles before performance decayed dramatically.

But there has been progress on all these fronts, and some lithium-sulfur batteries with performance similar to lithium-ion have been demonstrated. Late last year, a company announced that it had lined up the money needed to build the first large-scale lithium-sulfur battery factory. Still, work on improvements has continued, and the new work seems to suggest ways to boost performance well beyond lithium-ion.

The need for speed

The paper describing the new developments, done by a collaboration between Chinese and German researchers, focuses on one aspect of the challenges posed by lithium-sulfur batteries: the relatively slow chemical reaction between lithium ions and elemental sulfur. It presents that aspect as a roadblock to fast charging, something that will be an issue for automotive applications. But at the same time, finding a way to limit the formation of inactive intermediate products during this reaction goes to the root of the relatively short usable life span of lithium-sulfur batteries.

As it turns out, the researchers found two.

One of the problems with the lithium-sulfur reaction intermediates is that they dissolve in most electrolytes. But that’s not a problem if the electrolyte isn’t a liquid. Solid electrolytes are materials that have a porous structure at the atomic level, with the environment inside the pores being favorable for ions. This allows ions to diffuse through the solid. If there’s a way to trap ions on one side of the electrolyte, such as a chemical reaction that traps or de-ionizes them, then it can enable one-way travel.

Critically, pores that favor the transit of lithium ions, which are quite compact, aren’t likely to allow the transit of the large ionized chains of sulfur. So a solid electrolyte should help cut down on the problems faced by lithium-sulfur batteries. But it won’t necessarily help with fast charging.

The researchers began by testing a glass formed from a mixture of boron, sulfur, and lithium (B₂S₃ and Li₂S). But this glass had terrible conductivity, so they started experimenting with related glasses and settled on a combination that substituted in some phosphorus and iodine.

The iodine turned out to be a critical component. While the exchange of electrons with sulfur is relatively slow, iodine undergoes electron exchange (technically termed a redox reaction) extremely quickly. So it can act as an intermediate in the transfer of electrons to sulfur, speeding up the reactions that occur at the electrode. In addition, iodine has relatively low melting and boiling points, and the researchers suggest there’s some evidence that it moves around within the electrolyte, allowing it to act as an electron shuttle.

Successes and caveats

The result is a far superior electrolyte—and one that enables fast charging. It’s typical that fast charging cuts into the total capacity that can be stored in a battery. But when charged at an extraordinarily fast rate (50C, meaning a full charge in just over a minute), a battery based on this system still had half the capacity of a battery charged 25 times more slowly (2C, or a half-hour to full charge).

But the striking thing was how durable the resulting battery was. Even at an intermediate charging rate (5C), it still had over 80 percent of its initial capacity after over 25,000 charge/discharge cycles. By contrast, lithium-ion batteries tend to hit that level of decay after about 1,000 cycles. If that sort of performance is possible in a mass-produced battery, it’s only a slight exaggeration to say it can radically alter our relationships with many battery-powered devices.

What’s not at all clear, however, is whether this takes full advantage of one of the original promises of lithium-sulfur batteries: more charge in a given weight and volume. The researchers specify the battery being used for testing; one electrode is an indium/lithium metal foil, and the other is a mix of carbon, sulfur, and the glass electrolyte. A layer of the electrolyte sits between them. But when giving numbers for the storage capacity per weight, only the weight of the sulfur is mentioned.

Still, even if weight issues would preclude this from being stuffed into a car or cell phone, there are plenty of storage applications that would benefit from something that doesn’t wear out even with 65 years of daily cycling.

Nature, 2025. DOI: 10.1038/s41586-024-08298-9 (About DOIs).

John is Ars Technica’s science editor. He has a Bachelor of Arts in Biochemistry from Columbia University, and a Ph.D. in Molecular and Cell Biology from the University of California, Berkeley. When physically separated from his keyboard, he tends to seek out a bicycle, or a scenic location for communing with his hiking boots.

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Simple voltage pulse can restore capacity to Li-Si batteries

batteries, chemistry, electrochemistry, lithium, Science, silicon / Mike M. / October 19, 2024

The new work, then, is based on a hypothetical: What if we just threw silicon particles in, let them fragment, and then fixed them afterward?

As mentioned, the reason fragmentation is a problem is that it leads to small chunks of silicon that have essentially dropped off the grid—they’re no longer in contact with the system that shuttles charges into and out of the electrode. In many cases, these particles are also partly filled with lithium, which takes it out of circulation, cutting the battery’s capacity even if there’s sufficient electrode material around.

The researchers involved here, all based at Stanford University, decided there was a way to nudge these fragments back into contact with the electrical system and demonstrated it could restore a lot of capacity to a badly degraded battery.

Bringing things together

The idea behind the new work was that it could be possible to attract the fragments of silicon to an electrode, or at least some other material connected to the charge-handling network. On their own, the fragments in the anode shouldn’t have a net charge; when the lithium gives up an electron there, it should go back into solution. But the lithium is unlikely to be evenly distributed across the fragment, making them a polar material—net neutral, but with regions of higher and lower electron densities. And polar materials will move in an uneven electric field.

And, because of the uneven, chaotic structure of an electrode down at the nano scale, any voltage applied to it will create an uneven electric field. Depending on its local structure, that may attract or repel some of the particles. But because these are mostly within the electrode’s structure, most of the fragments of silicon are likely to bump into some other part of electrode in short order. And that could potentially re-establish a connection to the electrode’s current handling system.

To demonstrate that what should happen in theory actually does happen in an electrode, the researchers started by taking a used electrode and brushing some of its surface off into a solution. They then passed a voltage through the solution and confirmed the small bits of material from the battery started moving toward one of the electrodes that they used to apply a voltage to the solution. So, things worked as expected.

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Grid-scale batteries: They’re not just lithium

batteries, chemistry, Science / Rejus Almole / September 21, 2024

A shipping container labeled with a battery symbol, set among wind turbines and solar panels.

As power utilities and industrial companies seek to use more renewable energy, the market for grid-scale batteries is expanding rapidly. Alternatives to lithium-ion technology may provide environmental, labor, and safety benefits. And these new chemistries can work in markets like the electric grid and industrial applications that lithium doesn’t address well.

“I think the market for longer-duration storage is just now emerging,” said Mark Higgins, chief commercial officer and president of North America at Redflow. “We have a lot of… very rapid scale-up in the types of projects that we’re working on and the size of projects that we’re working on. We’ve deployed about 270 projects around the world. Most of them have been small off-grid or remote-grid systems. What we’re seeing today is much more grid-connected types of projects.”

“Demand… seems to be increasing every day,” said Giovanni Damato, president of CMBlu Energy. Media projections of growth in this space are huge. “We’re really excited about the opportunity to… just be able to play in that space and provide as much capacity as possible.”

New industrial markets are also becoming active. Chemical plants, steel plants, and metal processing plants have not been able to deploy renewable energy well so far due to batteries’ fire hazards, said Mukesh Chatter, co-founder and CEO of Alsym Energy. “When you already are generating a lot of heat in these plants and there’s a risk of fire to begin with, you don’t want to deploy any battery that’s flammable.”

Chatter said that the definition of long-duration energy storage is not agreed upon by industry organizations. Still, there are a number of potential contenders developing storage for this market. Here, we’ll look at Redflow, CMBlu Energy, and BASF Stationary Energy Storage.

Zinc-bromine batteries

Redflow has been manufacturing zinc-bromine flow batteries since 2010, Higgins said. These batteries do not require the critical minerals that lithium-ion batteries need, which are sometimes from parts of the world that have unsafe labor practices or geopolitical risks. The minerals for these zinc-bromine batteries are affordable and easy to obtain.

Flow batteries contain liquid or gaseous electrolytes that flow through cells from tanks, according to the International Flow Battery Forum website:

The interconversion of energy between electrical and stored chemical energy takes place in the electrochemical cell. This consists of two half cells separated by a porous or an ion-exchange membrane. The battery can be constructed of low-cost and readily available materials, such as thermoplastics and carbon-based materials. Many parts of the battery can be recycled. Electrolytes can be recovered and reused, leading to low cost of ownership.

Building these can be quite different from other batteries. “I would say that our manufacturing process is much more akin to… an automotive manufacturing process than to [an] electronics manufacturing process… like [a] lithium-ion battery,” Higgins said. “Essentially, it is assembling batteries that are made out of plastic tanks, pumps, fans, [and] tubing. It’s a flow battery, so it’s a liquid that flows through the system that goes through an electrical stack that has cells in it, which is where most of Redflow’s intellectual property resides. The rest of the battery is all… parts that we can obtain just about anywhere.”

The charging and discharging happen inside an electrical stack. In the stack, zinc is plated onto a carbon surface during the charging process. It is then dissolved into the liquid during the discharging process, Higgins said.

The zinc-bromine electrolyte is derived from an industrial chemical that has been used in the oil and gas sector for a long time, Higgins added.

This battery cannot catch fire, and all of its parts are recyclable, Higgins told Ars. “You don’t have any of the toxic materials that you do in a lithium-ion battery.” The electrolyte liquid can be reused in other batteries. If it’s contaminated, it can be used by the oil and gas industry. If the battery leaks, the contents can be neutralized quickly and are subsequently not hazardous.

“Right now, we manufacture our batteries in Thailand,” Higgins said. “The process and wages are all fair wages and we follow all relevant environmental and labor standards.” The largest sources of bromine come from the Dead Sea or within the United States. The zinc comes from Northern Europe, the United States, or Canada.

The batteries typically use an annual maintenance program to replace components that wear out or fail, something that’s not possible with many other battery types. Higgins estimated that two to four years down the road, this technology will be “completely competitive with lithium-ion” from a cost perspective. Some government grants have helped with the commercialization process.

Grid-scale batteries: They’re not just lithium Read More »

US grid adds batteries at 10x the rate of natural gas in first half of 2024

batteries, Energy, green, natural gas, nuclear, renewable energy, Science, solar, Sustainability, Wind / Kris Guyer / August 26, 2024

In transition —

By year’s end, 96 percent of the US’s grid additions won’t add carbon to the atmosphere.

John Timmer – Aug 26, 2024 5: 41 pm UTC

While solar power is growing at an extremely rapid clip, in absolute terms, the use of natural gas for electricity production has continued to outpace renewables. But that looks set to change in 2024, as the US Energy Information Agency (EIA) has run the numbers on the first half of the year and found that wind, solar, and batteries were each installed at a pace that dwarfs new natural gas generators. And the gap is expected to get dramatically larger before the year is over.

Solar, batteries booming

According to the EIA’s numbers, about 20 GW of new capacity was added in the first half of this year, and solar accounts for 60 percent of it. Over a third of the solar additions occurred in just two states, Texas and Florida. There were two projects that went live that were rated at over 600 MW of capacity, one in Texas, the other in Nevada.

Next up is batteries: The US saw 4.2 additional gigawatts of battery capacity during this period, meaning over 20 percent of the total new capacity. (Batteries are treated as the equivalent of a generating source by the EIA since they can dispatch electricity to the grid on demand, even if they can’t do so continuously.) Texas and California alone accounted for over 60 percent of these additions; throw in Arizona and Nevada, and you’re at 93 percent of the installed capacity.

The clear pattern here is that batteries are going where the solar is, allowing the power generated during the peak of the day to be used to meet demand after the sun sets. This will help existing solar plants avoid curtailing power production during the lower-demand periods in the spring and fall. In turn, this will improve the economic case for installing additional solar in states where its production can already regularly exceed demand.

Wind power, by contrast, is running at a more sedate pace, with only 2.5 GW of new capacity during the first six months of 2024. And for likely the last time this decade, additional nuclear power was placed on the grid, at the fourth 1.1 GW reactor (and second recent build) at the Vogtle site in Georgia. The only other additions came from natural gas-powered facilities, but these totaled just 400 MW, or just 2 percent of the total of new capacity.

Enlarge / Wind, solar, and batteries are the key contributors to new capacity in 2024.

The EIA has also projected capacity additions out to the end of 2024 based on what’s in the works, and the overall shape of things doesn’t change much. However, the pace of installation goes up as developers rush to get their project operational within the current tax year. The EIA expects a bit over 60 GW of new capacity to be installed by the end of the year, with 37 GW of that coming in the form of solar power. Battery growth continues at a torrid pace, with 15 GW expected, or roughly a quarter of the total capacity additions for the year.

Wind will account for 7.1 GW of new capacity, and natural gas 2.6 GW. Throw in the contribution from nuclear, and 96 percent of the capacity additions of 2024 are expected to operate without any carbon emissions. Even if you choose to ignore the battery additions, the fraction of carbon-emitting capacity added remains extremely small, at only 6 percent.

Gradual shifts on the grid

Obviously, these numbers represent the peak production of these sources. Over a year, solar produces at about 25 percent of its rated capacity in the US, and wind at about 35 percent. The former number will likely decrease over time as solar becomes inexpensive enough to make economic sense in places that don’t receive as much sunshine. By contrast, wind’s capacity factor may increase as more offshore wind farms get completed. For natural gas, many of the newer plants are being designed to operate erratically so that they can provide power when renewables are under-producing.

A clearer sense of what’s happening comes from looking at the generating sources that are being retired. The US saw 5.1 GW of capacity drop off the grid in the first half of 2024, and aside from a 0.2 GW of “other,” all of it was fossil fuel-powered, including 2.1 GW of coal capacity and 2.7 GW of natural gas. The latter includes a large 1.4 GW natural gas plant in Massachusetts.

But total retirements are expected to be just 7.5 GWO this year—less than was retired in the first half of 2023. That’s likely because the US saw electricity use rise by 5 percent in the first half of 2025, based on numbers the EIA released on Friday (note that this link will take you to more recent data a month from now). It’s unclear how much of that was due to weather—a lot of the country saw heat that likely boosted demand for air conditioning—and how much could be accounted for by rising use in data centers and for the electrification of transit and appliances.

That data release includes details on where the US got its electricity during the first half of 2024. The changes aren’t dramatic compared to where they were when we looked at things last month. Still, what has changed over the past month is good news for renewables. In May, wind and solar production were up 8.4 percent compared to the same period the year before. By June, they were up by over 12 percent.

Given the EIA’s expectations for the rest of the year, the key question is likely to be whether the pace of new solar installations is going to be enough to offset the drop in production that will occur as the US shifts to the winter months.

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Electric vehicle battery fires—what to know and how to react

batteries, battery fires, Cars, EVs, syndication, Tesla / Mike M. / August 24, 2024

sick burns —

It’s very rare, but lithium-ion batteries in electric vehicles can catch fire.

Reece Rogers, wired.com – Aug 24, 2024 11: 17 am UTC

Enlarge / The battery pack of a Volkswagen ID. Buzz electric microbus on the assembly line during a media tour of the Volkswagen AG multipurpose and commercial vehicle plant in Hannover, Germany, on Thursday, June 16, 2022.

Lithium-ion battery fires can be intense and frightening. As someone who used to repair second-hand smartphones, I’ve extinguished my fair share of flaming iPhones with punctured lithium-ion batteries. And the type of smartphone battery in your pocket right now is similar to what’s inside of electric vehicles. Except, the EV battery stores way more energy—so much energy that some firefighters are receiving special training to extinguish the extra-intense EV flames that are emitted by burning EV batteries after road accidents.

If you’ve been reading the news about EVs, you’ve likely encountered plenty of scary articles about battery fires on the rise. Recently, the US National Transportation Safety Board and the California Highway Patrol announced they are investigating a Tesla semi truck fire that ignited after the vehicle struck a tree. The lithium-ion battery burned for around four hours.

Does this mean that you should worry about your personal electric vehicle as a potential fire hazard? Not really. It makes more sense to worry about a gas-powered vehicle going up in flames than an electric vehicle, since EVs are less likely to catch fire than their more traditional transportation counterparts.

“Fires because of battery manufacturing defects are really very rare,” says Matthew McDowell, a codirector of Georgia Tech’s Advanced Battery Center. “Especially in electric vehicles, because they also have battery management systems.” The software keeps tabs on the different cells that comprise an EV’s battery and can help prevent the battery from being pushed beyond its limits.

How do electric vehicle fires happen?

During a crash that damages the EV battery, a fire may start with what’s called thermal runaway. EV batteries aren’t one solid brick. Rather, think of these batteries as a collection of many smaller batteries, called cells, pressed up against each other. With thermal runaway, a chemical reaction located in one of the cells lights an initial fire, and the heat soon spreads to each adjacent cell until the entire EV battery is burning.

Greg Less, director of the University of Michigan’s Battery Lab, breaks down EV battery fires into two distinct categories: accidents and manufacturing defects. He considers accidents to be everything from a collision that punctures the battery to a charging mishap. “Let’s take those off the table,” says Less. “Because, I think people understand that, regardless of the vehicle type, if you’re in an accident, there could be a fire.”

While all EV battery fires are hard to put out, fires from manufacturing defects are likely more concerning to consumers, due to their seeming randomness. (Think back to when all those Samsung phones had to be recalled because battery issues made them fire hazards.) How do these rare issues with EV battery manufacturing cause fires at what may feel like random moments?

It all comes down to how the batteries are engineered. “There’s some level of the engineering that has gone wrong and caused the cell to short, which then starts generating heat,” says Less. “Heat causes the liquid electrolyte to evaporate, creating a gas inside the cell. When the heat gets high enough, it catches fire, explodes, and then propagates to other cells.” These kinds of defects are likely what caused the highly publicized recent EV fires in South Korea, one of which damaged over a hundred vehicles in a parking lot.

How to react if your EV catches fire

According to the National Fire Prevention Agency, if an EV ever catches fire while you’re behind the wheel, immediately find a safe way to pull over and get the car away from the main road. Then, turn off the engine and make sure everyone leaves the vehicle immediately. Don’t delay things by grabbing personal belongings, just get out. Remain over 100 feet away from the burning car as you call 911 and request the fire department.

Also, you shouldn’t attempt to put out the flame yourself. This is a chemical fire, so a couple buckets of water won’t sufficiently smother the flames. EV battery fires can take first responders around 10 times more water to extinguish than a fire in a gas-powered vehicle. Sometimes the firefighters may decide to let the battery just burn itself out, rather than dousing it with water.

Once an EV battery catches fire, it’s possible for the chemical fire to reignite after the initial burn dies down. It’s even possible for the battery to go up in flames again days later. “Both firefighters and secondary responders, such as vehicle recovery or tow companies, also need to be aware of the potential for stranded energy that may remain in the undamaged portions of the battery,” says Thomas Barth, an investigator and biomechanics engineer for the NTSB, in an emailed statement. “This energy can pose risks for electric shock or cause the vehicle to reignite.”

Although it may be tempting to go back into the car and grab your wallet or other important items if the flame grows smaller or goes out for a second, resist the urge. Wait until your local fire department arrives to assess the overall situation and give you the all clear. Staying far away from the car also helps minimize your potential for breathing in unhealthy fumes emitted from the battery fire.

How could EV batteries be safer?

In addition to quick recalls and replacements of potentially faulty lithium-ion batteries, both researchers I spoke with were excited about future possibilities for a different kind of battery, called solid-state, to make EVs even more reliable. “These batteries could potentially show greater thermal stability than lithium-ion batteries,” says McDowell. “When it heats up a lot, it may just remain pretty stable.” With a solid-state battery, the liquid electrolyte is no longer part of battery cells, removing the most flammable aspect of battery design.

These solid-state batteries are already available in some smaller electronics, but producing large versions of the batteries at vast scale continues to be a hurdle that EV manufacturers are working to overcome.

This story originally appeared on wired.com.

Electric vehicle battery fires—what to know and how to react Read More »

Electric eels inspire novel “jelly” batteries for soft robotics, wearables

batteries, biomimicry, electric eels, Science / Paul Patrick / July 17, 2024

Soft and stretchy —

Another team built a lithium-ion battery with electrolyte layer that expands by 5,000%.

Jennifer Ouellette – Jul 17, 2024 6: 01 pm UTC

closeup of colorful strand held between fingers being stretched — Enlarge / Researchers have developed soft, stretchable “jelly batteries” that could be used for wearable devices or soft robotics.

University of Cambridge

Inspired by the electric shock capabilities of electric eels, scientists have developed a soft, stretchable “jelly” battery ideal for wearable devices or soft robotics, according to a new paper published in the journal Science Advances. With further testing in living organisms, the batteries might even be useful as brain implants for targeted drug delivery to treat epilepsy, among other conditions.

As previously reported, the electric eel produces its signature electric discharges—both low and high voltages, depending on the purpose for discharging—via three pairs of abdominal organs composed of modified muscle cells called electrocytes, located symmetrically along both sides of the eel. The brain sends a signal to the electrocytes, opening ion channels and briefly reversing the polarity. The difference in electric potential then generates a current, much like a battery with stacked plates.

Vanderbilt University biologist and neuroscientist Kenneth Catania is one of the most prominent scientists studying electric eels these days. He has found that the creatures can vary the degree of voltage in their electrical discharges, using lower voltages for hunting purposes and higher voltages to stun and kill prey. Those higher voltages are also useful for tracking potential prey, akin to how bats use echolocation. One species, Volta’s electric eel (Electrophorus voltai), can produce a discharge of up to 860 volts. In theory, if 10 such eels discharged at the same time, they could produce up to 8,600 volts of electricity—sufficient to power 100 light bulbs.

Mimicking Mother Nature

For soft robotics or wearable electronics applications, soft and stretchy devices with tissue-like electronic properties are required. However, “It’s difficult to design a material that is both highly stretchable and highly conductive since those two properties are normally at odds with one another,” said co-author Stephen O’Neill of the University of Cambridge. “Typically, conductivity decreases when a material is stretched.” So he and his colleagues decided to model their jelly battery design on the layered structure of the electric eel’s electrocytes. Whereas conventional electronics employ rigid materials with electrons to carry the charges, this battery would use ions as charge carriers, like the electric eels.

Enlarge / The self-healing jelly batteries can stretch to over 10 times their original length without affecting their conductivity.

University of Cambridge

Hydrogels—3D polymer networks composed of 60 percent water—were the obvious choice since they confer the ability to precisely control mechanical properties and can mimic human skin. They are usually made of neutrally charged polymers, but O’Neill et al. added a charge to their polymers, altering the salt component to make them sticky enough to squish together into multiple layers. This builds up a larger energy potential.

The stickiness of the hydrogels comes from the reversible bonds that form between the different layers, thanks to barrel-shaped molecules that act a bit like “molecular handcuffs,” per the authors. So, the jelly batteries can stretch without separating the layers and without any loss of conductivity. Furthermore, “We can customize the mechanical properties of the hydrogels so they match human tissue,” said co-author Oren Scherman. “Since they contain no rigid components such as metal, a hydrogel implant would be much less likely to be rejected by the body or cause the build-up of scar tissue.” That makes them promising for future biomedical applications.

Another stretchy battery

Enlarge / This lithium-ion battery has entirely stretchable components and stable charging and discharging capacity over time.

Shi Wang et al., ACS Energy Letters, 2024

In related research, a new paper published in the journal ACS Energy Letters described the fabrication of a lithium-ion battery with stretchable components, including an electrolyte layer that can expand by 5,000 percent. The battery can retain its charge storage capacity after nearly 70 charge/discharge cycles. Rather than using a liquid electrolyte, a team of Chinese scientists incorporated the electrolyte into a polymer layer fused between two flexible electrode films.

The electrodes consisted of a thin film of conductive paste embedded with silver nanowires, carbon black, and lithium-based cathode or anode materials onto a plate. They applied a layer of flexible polydimethylsiloxane (used in contact lenses) on top of the paste, followed by a lithium salt, highly conductive liquid, and stretchy polymer ingredients. When zapped with light, all those components formed a solid rubber-like stretchy layer that could still transport lithium ions. This was topped with another electrode film, and the entire device was then sealed in a protective coating. This battery had a roughly six times higher average charge capacity at a fast-charging rate than a similar device with a traditional liquid electrolyte.

Science Advances, 2024. DOI: 10.1126/sciadv.adn5142 (About DOIs).

ACS Energy Letters, 2024. DOI: 10.1021/acsenergylett.4c01254 (About DOIs).

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TDK claims insane energy density in solid-state battery breakthrough

batteries, solid state batteries, syndication, TDK, Tech / Mike M. / June 17, 2024

All charged up —

Apple supplier says new tech has 100 times the capacity of its current batteries.

Financial Times – Jun 17, 2024 1: 35 pm UTC

man wearing headphones — Enlarge / TDK says its new ceramic materials for batteries will improve the performance of small consumer electronics devices such as smartwatches and wireless headphones

Japan’s TDK is claiming a breakthrough in materials used in its small solid-state batteries, with the Apple supplier predicting significant performance increases for devices from wireless headphones to smartwatches.

The new material provides an energy density—the amount that can be squeezed into a given space—of 1,000 watt-hours per liter, which is about 100 times greater than TDK’s current battery in mass production. Since TDK introduced it in 2020, competitors have moved forward, developing small solid-state batteries that offer 50 Wh/l, while rechargeable coin batteries using traditional liquid electrolytes offer about 400 Wh/l, according to the group.

“We believe that our newly developed material for solid-state batteries can make a significant contribution to the energy transformation of society. We will continue the development towards early commercialisation,” said TDK’s chief executive Noboru Saito.

The batteries set to be produced will be made of an all-ceramic material, with oxide-based solid electrolyte and lithium alloy anodes. The high capability of the battery to store electrical charge, TDK said, would allow for smaller device sizes and longer operating times, while the oxide offered a high degree of stability and thus safety. The battery technology is designed to be used in smaller-sized cells, replacing existing coin-shaped batteries found in watches and other small electronics.

The breakthrough is the latest step forward for a technology industry experts think can revolutionize energy storage, but which faces significant obstacles on the path to mass production, particularly at larger battery sizes.

Solid-state batteries are safer, lighter and potentially cheaper and offer longer performance and faster charging than current batteries relying on liquid electrolytes. Breakthroughs in consumer electronics have filtered through to electric vehicles, although the dominant battery chemistries for the two categories now differ substantially.

The ceramic material used by TDK means that larger-sized batteries would be more fragile, meaning the technical challenge of making batteries for cars or even smartphones will not be surmounted in the foreseeable future, according to the company.

Kevin Shang, senior research analyst at Wood Mackenzie, a data and analytics firm, said that “unfavorable mechanical properties,” as well as the difficulty and cost of mass production, are challenges for moving the application of solid-state oxide-based batteries into smartphones.

Industry experts believe the most significant use case for solid-state batteries could be in electric cars by enabling greater driving range. Japanese companies are in the vanguard of a push to commercialize the technology: Toyota is aiming for as early as 2027, Nissan the year after and Honda by the end of the decade.

Car manufacturers are focused on developing sulfide-based electrolytes for long-range electric vehicles, an alternative kind of material to the oxide-based material that TDK has developed.

However, there is still skepticism about how quickly the much-hyped technology can be realized, particularly the larger batteries needed for electric vehicles.

Robin Zeng, founder and chief executive of CATL, the world’s biggest electric vehicle battery manufacturer, told the Financial Times in March that solid-state batteries did not work well enough, lacked durability and still had safety problems. Zeng’s CATL originated as a spin-off from Amperex Technology, or ATL, which is a subsidiary of TDK and is the world’s leading producer of lithium-ion batteries.

TDK, which was founded in 1935 and became a household name as a top cassette tape brand in the 1960s and 1970s, has lengthy experience in battery materials and technology.

It has 50 to 60 percent global market share in the small-capacity batteries that power smartphones and is targeting leadership in the medium-capacity market, which includes energy storage devices and larger electronics such as drones.

The group plans to start shipping samples of its new battery prototype to clients from next year and hopes to be able to move into mass production after that.

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