Batteries, those irritating squares inside phones that everyone loves to hate. But while they may help gadgets cut the power cord in consumer electronics, their energy-storing abilities could help humanity transition away from fossil fuels. A slew of technologies could take those abilities to new levels.
While the likes of coal and gas are easily scaled to match grid demand, renewable energy sources like wind and solar provide power on an intermittent basis. An energy storage solution can collect the power as it’s generated, then distribute it 24 hours a day. Throw vehicle-to-grid technologies into the mix, which enable electric car batteries to plug into the grid and play the same role, and you have a comprehensive green energy storage plan.
But lithium-ion batteries can be expensive, dangerous, slow to charge, difficult to mine and hard to recycle. They cost around $156 per kilowatt-hour, a figure that adds up when placing a 100-kilowatt-hour battery into a high-end electric car. Wood Mackenzie research found global lithium-ion production reached 285 gigawatt-hours per year by November 2019. The researchers claim that’s around enough batteries to transition the eastern and central United States grid onto renewables, not quite enough for a full-blown global transition.
There are efforts on these fronts to make batteries better. Firms like Tesla are working to remove controversial elements like cobalt, while big factories like CATL are seeking to bring prices down by increasing production.
Some of the biggest energy storage breakthroughs could come from more fundamental research. Here are the coolest battery technologies set to make a splash.
6. REDOX FLOW
Picture a giant vat storing a liquid, which can hold large amounts of energy. That’s the basic idea behind a redox flow battery, an alternative approach that could enable giant, cheap batteries for grid-scale storage.
In a traditional lithium-ion battery, the active materials that store the charge are solid. The battery is filled with a liquid electrolyte solution, which enables the electrons to move around and leave the battery. Redox flow replaces the solids with a liquid alternative, while also decoupling from the electrolytes to place them in separate tanks.
James McKone, assistant professor at the University of Pittsburgh’s Swanson School of Engineering who is researching redox flow batteries, tells Inverse that the best analogy is to think about food. A lithium-ion battery is like a pre-prepared TV dinner where the energy is ready to go. Redox flow batteries are more like a giant grain silo: it’s a cheap way to store a whole lot of food, but it’ll need some processing first.
“That is expected to give several really important advantages when you implement the battery on a very large scale,” McKone says. It means a much lower cost per delivered unit of energy, a difference that gets larger with more storage as it’s just a case of making the tanks bigger.
It’s not all good news at this stage. The energy density is also much lower versus a regular battery. That’s fine for grid-scale applications, but terrible for electric cars where space and weight are a premium. Researchers have also struggled with issues like expensive fluids, which have pushed manufacturers away from scaling up production versus lithium-ion. UtilityDive reported in 2017 that 97 percent of grid-scale installations in the United States over the past two years used lithium-ion.
5. GRID-SCALE LITHIUM-ION
Making a better grid-scale battery doesn’t necessarily mean throwing out all the benefits of lithium-ion. Idaho-based Kore Power is one firm that’s focused on grid-scale lithium-ion cells, using patented chemistry to achieve similar goals.
“You want to put as much energy in a cubic meter as you can,” Lindsay Gorrill, CEO of Kore Power, tells Inverse. “So we focused on, how do we revamp the chemical composition of the cell to put as much as you can into a cubic meter.”
Kore Power, which Gorrill claims is the only firm he’s aware of fully focused on lithium-ion grid storage, can leverage a few advantages due to the unique nature of grid storage. Their rack systems reach up to the 1,500-volt range, which reduces the amount of energy loss. Gorrill also claims that, as the firm cares more about saving space than saving weight, it’s able to save suppliers money by reducing the amount of land use.
4. WATER-BASED BATTERIES
In many respects, water-based batteries are nothing new. Lead-acid batteries use water mixed with sulfuric acid as their liquid electrolyte. Water-based cells could be cheaper in terms of raw materials, safer for the environment, and from a scientific perspective could hold great promise.
“I’m very pro-water as the basis of battery technology,” McKone says, who describes them as an “underdeveloped opportunity.” The reason they have been under-explored, McKone suggests, is because lithium-ion can reach much higher voltages than current water-based batteries.
While lead-acid batteries are toxic and environmentally harmful, research into water-based cells has shown promise. A team of researchers at Stanford University in 2018 developed a manganese-hydrogen battery that could withstand 10,000 charge cycles. The cell could also store enough energy to power a 100-watt bulb for 12 hours at a cost of just one cent.
3. BIODEGRADABLE BATTERIES
Batteries can take around 100 years to decompose, and research from Texas A&M University found that only around five percent of lithium-ion cells are recycled. A biodegradable battery could make them more environmentally friendly.
Texas A&M researchers in August 2019 announced they had built a battery that used polypeptides as opposed to metal compounds. The team is hopeful that such technologies could work for wearable sensors and other applications where longevity is less of an issue.
But research in this area is otherwise limited. McKone says the prospects are “really exciting,” particularly from an environmental perspective.
“I’d even go so far as to say I would love to build a compostable battery, which is that not only does it degrade, but it actually feeds the earth when you dispose of it,” McKone says.
2. SOLID-STATE BATTERIES
These lithium-ion batteries replace the liquid electrolytes with solid components instead. That means they remove the flammable hydrocarbons, making them more suitable for electric cars. They could also store more energy: Doug Campbell, CEO of Solid Power, told Inverse in January 2018 that they could store twice the amount of energy.
While more energy and better safety seem great, they come at a cost. Solid electrolytes don’t flow through the battery so easily, which leads to longer charging times. As the electric car industry manages to reach below half an hour to recharge a car, it’s a sacrifice drivers may be unwilling to make.
“Most of the solid-state stuff that I’m aware of, I would describe it as incremental,” McKone says.
1. ALUMINUM-BASED ENERGY STORAGE
Grid-based energy storage could come from thermal heating. Sweden-based Azelio has developed a long-duration thermal battery, which heats a recycled aluminum alloy to 600 degrees Celsius. This can be transferred to a generator for on-demand, zero-emissions energy. It doesn’t use rare elements like the cobalt found in lithium-ion batteries, and the company claims it doesn’t degrade over time.
“What’s really needed out there is a way to build this decentralized renewable energy storage, and to have dispatchable renewable electricity available 24 hours a day,” Jonas Eklind, CEO of Azelio, tells Inverse.
The idea bears resemblance to concentrated solar power, where mirrors concentrate rays onto a tank that heats an internal material like molten salt. This is then stored, then used to generate steam and turn a turbine when needed. But Eklind claims Azelio’s technology, paired with traditional photovoltaic solar cells, would be more cost-efficient, particularly on the smaller scale.
Although it’s in the early stages, Azelio is developing three verification projects in Morocco, Sweden and Abu Dhabi. The goal will be to start industrial production in the summer of 2021, producing 19.6 megawatts per year.
Electric planes could be the future of aviation. In theory, they will be much quieter, cheaper, and cleaner than the planes we have today. Electric planes with a 1,000 km (620 mile) range on a single charge could be used for half of all commercial aircraft flights today, cutting global aviation’s carbon emissions by about 15%.
It’s the same story with electric cars. An electric car isn’t simply a cleaner version of its pollution-spewing cousin. It is, fundamentally, a better car: Its electric motor makes little noise and provides lightning-fast response to the driver’s decisions. Charging an electric car costs much less than paying for an equivalent amount of gasoline. Electric cars can be built with a fraction of moving parts, which makes them cheaper to maintain.
So why aren’t electric cars everywhere already? It’s because batteries are expensive, making the upfront cost of an electric car much higher than a similar gas-powered model. And unless you drive a lot, the savings on gasoline don’t always offset the higher upfront cost. In short, electric cars still aren’t economical.
Similarly, current batteries don’t pack in enough energy by weight or volume to power passenger aircrafts. We still need fundamental breakthroughs in battery technology before that becomes a reality.
Battery-powered portable devices have transformed our lives. But there’s a lot more that can batteries can disrupt, if only safer, more powerful, and energy-dense batteries could be made cheaply. No law of physics precludes their existence.
And yet, despite over two centuries of close study since the first battery was invented in 1799, scientists still don’t fully understand many of the fundamentals of what exactly happens inside these devices. What we do know is that there are, essentially, three problems to solve in order for batteries to truly transform our lives yet again: power, energy, and safety.
THERE ISN’T A ONE-SIZE-FITS-ALL LITHIUM-ION BATTERY
Every battery has two electrodes: a cathode and an anode. Most anodes of lithium-ion batteries are made of graphite, but cathodes are made of various materials, depending on what the battery will be used for. Below, you can see how different cathode materials change the way battery types perform on six measures.
The power challenge
In common parlance, people use “energy” and “power” interchangeably, but it’s important to differentiate between them when talking about batteries. Power is the rate at which energy can be released.
A battery strong enough to launch and keep aloft a commercial jet for 1,000 km requires a lot of energy to be released in very little time, especially during takeoff. So it’s not just about having lots of energy stored but also having the ability to extract that energy very quickly.
Tackling the power challenge requires us to look inside the black box of commercial batteries. It’s going to get a little nerdy, but bear with me. New battery technologies are often overhyped because most people don’t look closely enough at the details.
The most cutting-edge battery chemistry we currently have is lithium-ion. Most experts agree that no other chemistry is going disrupt lithium-ion for at least another decade or more. A lithium-ion battery has two electrodes (cathode and anode) with a separator (a material that conducts ions but not electrons, designed to prevent shorting) in the middle and an electrolyte (usually liquid) to enable the flow of lithium ions back and forth between the electrodes. When a battery is charging, the ions travel from the cathode to the anode; when the battery is powering something, the ions move in the opposite direction.
Imagine two loaves of sliced bread. Each loaf is an electrode: the left one is the cathode and the right is one the anode. Let’s assume the cathode is made up of slices of nickel, manganese, and cobalt (NMC)—one of the best in the class—and that the anode is made up of graphite, which is essentially layered sheets, or slices, of carbon atoms.
In the discharged state—i.e., after it has been drained of energy—the NMC loaf has lithium ions sandwiched between each slice. When the battery is charging, each lithium ion is extracted from between the slices and forced to travel through the liquid electrolyte. The separator acts as a checkpoint ensuring only lithium ions pass through to the graphite loaf. When fully charged, the battery’s cathode loaf will have no lithium ions left; they will all be neatly sandwiched between the slices of the graphite loaf. As the battery’s energy is consumed, the lithium ions travel back to the cathode, until there are none left in the anode. That’s when the battery needs to be charged again.
The battery’s power capacity is determined by, essentially, how fast this process happens. But it’s not so simple to turn up the speed. Drawing lithium-ions out of the cathode loaf too quickly can cause the slices to develop flaws and eventually break down. It’s one reason why the longer we use our smartphone, laptop, or electric car, the worse their battery life gets. Every charge and discharge causes the loaf to weaken that little bit.
Various companies are working on solutions to the problem. One idea is to replace layered electrodes with something structurally stronger. For example, the 100-year-old Swiss battery company Leclanché is working on a technology that uses lithium iron phosphate (LFP), which has an “olivine” structure, as the cathode, and lithium titanate oxide (LTO), which has a “spinel” structure, as the anode. These structures are better at handling the flow of lithium ions in and out of the material.
Leclanché currently uses its battery cells in autonomous warehouse forklifts, which can be charged to 100% in nine minutes. For comparison, the best Tesla supercharger can charge a Tesla car battery to about 50% in 10 minutes. Leclanché is also deploying its batteries in the UK for fast-charging electric cars. These batteries sit at the charging station slowly drawing small amounts of power over a long period from the grid until they are fully charged. Then, when a car docks, the docking-station batteries quick-charge the car’s battery. When the car leaves, the station battery starts recharging again.
Efforts like Leclanché’s show it’s possible to tinker with battery chemistries to increase their power. Still, nobody has yet built a battery powerful enough to rapidly deliver the energy needed for a commercial plane to defeat gravity. Startups are looking to build smaller planes (seating up to 12 people), which could fly on relatively lower power-dense batteries, or electric hybrid planes, where jet fuel does the hard lifting and batteries do the coasting.
But there’s really no company working in this space anywhere near commercialization. Further, the kind of technological leap required for an all-electric commercial plane will likely take decades, says Venkat Viswanathan, a battery expert at Carnegie Mellon University.
REUTERS/ALISTER DOYLE A two-seat electric plane made by Slovenian firm Pipistrel stands outside a hangar at Oslo Airport, Norway.
The energy challenge
The Tesla Model 3, the company’s most affordable model, starts at $35,000. It runs on a 50 kWh battery, which costs approximately $8,750, or 25% of the total car price.
That’s still amazingly affordable compared to not that long ago. According to Bloomberg New Energy Finance, the average global cost for lithium-ion batteries in 2018 was about $175 per kWh—down from nearly $1,200 per kWh in 2010.
The US Department of Energy calculates that once battery costs fall below $125 per kWh, owning and operating an electric car will be cheaper than a gas-powered car in most parts of the world. It doesn’t mean electric vehicles will win over gas-powered vehicles in all niches and domains—for example, long-haul trucks don’t yet have an electric solution. But it’s a tipping point where people will start to prefer electric cars simply because they will make more economical sense in most cases.
One way to get there is to increase the energy density of batteries—to cram more kWh into a battery pack without lowering its price. Battery chemist can do that, in theory, by increasing the energy density of either the cathode or the anode, or both.
The most energy-dense cathode on the way to commercial availability is NMC 811 (each digit in the number represents the ratio of nickel, manganese, and cobalt, respectively, in the mix). It’s not yet perfect. The biggest problem is that it can only withstand a relatively small number of charge-discharge life cycles before it stops working. But experts predict that industry R&D should solve the problems of the NMC 811 within the next five years. When that happens, batteries using NMC 811 will have higher energy density by 10% or more.
However, a 10% increase is not that much in the big picture.
And, while a series of innovations over the past few decades have pushed the energy density of cathodes ever higher, anodes are where the biggest energy-density opportunities lie.
Graphite has been and remains far and away the dominant anode material. It’s cheap, reliable, and relatively energy dense, especially compared to current cathode materials. But it’s fairly weak when stacked up against other potential anode materials, like silicon and lithium.
Silicon, for example, is theoretically much better at absorbing lithium ions as graphite. That’s why a number of battery companies are trying to pepper some silicon in with the graphite in their anode designs; Tesla CEO Elon Musk has said his company is already doing this in its lithium-ion batteries.
A bigger step would be to develop a commercially viable anode made completely from silicon. But the element has traits that make this difficult. When graphite absorbs lithium ions, its volume does not change much. A silicon anode, however, swells to four times its original volume in the same scenario.
Unfortunately, you can’t just make the casing bigger to accommodate that swelling, because the expansion breaks apart what’s called the “solid electrolyte interphase,” or SEI, of the silicon anode.
You can think of the SEI as a sort of protective layer that the anode creates for itself, similar to the way that iron forms rust, also known as iron oxide, to protect itself from the elements: When you leave a piece of newly forged iron outside, it slowly reacts with the oxygen in the air to rust. Underneath the layer of rust, the rest of the iron doesn’t suffer from the same fate and thus retains the structural integrity.
At the end of a battery’s first charge, the electrode forms it’s own “rust” layer—the SEI—separating the uneroded part of the electrode from the electrolyte. The SEI stops additional chemical reactions from consuming the electrode, ensuring that lithium ions can flow as smoothly as possible.
But with a silicon anode, the SEI breaks apart every time the battery is used to power something up, and reforms every time the battery is charged. And during each charge cycle, a little bit of silicon is consumed. Eventually, the silicon dissipates to the point where the battery no longer works.
Over the last decade, a few Silicon Valley startups have been working to solve this problem. For example, Sila Nano’s approach is to encase silicon atoms inside a nano-sized shell with lots of empty room inside. That way, the SEI is formed on the outside of the shell and the expansion of silicon atoms happens inside it without shattering the SEI after each charge-discharge cycle. The company, valued at $350 million, says its technology will power devices as soon as 2020.
Enovix, on the other hand, applies a special manufacturing technique to put a 100% silicon anode under enormous physical pressure, forcing it to absorb fewer lithium ion and thus restricting the expansion of the anode and preventing the SEI from breaking. The company has investments from Intel and Qualcomm, and it also expects to have its batteries in devices by 2020.
These compromises mean the silicon anode can’t reach its theoretical high energy density. However, both companies say their anodes perform better than a graphite anode. Third parties are currently testing both firms’ batteries.
TESLA In 2020, the new Tesla Roadster is set to become the first electric car that offers 1,000 km (620 miles) on a single charge.
The safety challenge
All the molecular tinkering done to pack more energy in batteries can come at the cost of safety. Ever since its invention, the lithium-ion battery has caused headaches because of how often it catches fire. In the 1990s, for example, Canada’s Moli Energy commercialized a lithium-metal battery for use in phones. But out in the real world, its batteries started catching fire, and Moli was forced to make a recall, and, eventually, file for bankruptcy. (Some of its assets were bought by a Taiwanese company and it still sells lithium-ion batteries the brand name E-One Moli Energy.) More recently, Samsung’s Galaxy Note 7 smartphones, which were made with modern lithium-ion batteries, started exploding in people’s pockets. The resulting 2016 product recall cost the South Korean giant $5.3 billion.
Today’s lithium-ion batteries still have inherent risks, because they almost always use flammable liquids as the electrolyte. It’s one of nature’s unfortunate (for us humans) quirks that liquids able to easily transport ions also tend to have a lower threshold to catching fire. One solution is to use solid electrolytes. But that means other compromises. A battery design can easily include a liquid electrolyte that’s in contact with every bit of the electrodes—making it able to efficiently transfer ions. It’s much harder with solids. Imagine dropping a pair of dice into a cup of water. Now imagine dropping those same dice into a cup of sand. Obviously, the water will touch far more surface area of the dice than the sand will.
So far, the commercial use of lithium-ion batteries with solid electrolytes has been limited to low-power applications, such as for internet-connected sensors. The efforts to scale up solid-state batteries—that is, containing no liquid electrolyte—can be broadly classified into two categories: solid polymers at high temperatures and ceramics at room temperature.
SOLID POLYMERS AT HIGH TEMPERATURES
Polymers are long chains of molecules linked up together. They’re extremely common in everyday applications—single-use plastic bags are made of polymers, for example. When some types of polymers are heated, they behave like liquids, but without the flammability of the liquid electrolytes used in most batteries. In other words, they have the high ion conductivity as a liquid electrolyte without the risks.
But they have limitations. They can only operate at temperatures above 105°C (220°F), which means they aren’t practical options for, say, smartphones. But they can be used for storing energy from the grid in home batteries, for example. At least two companies—US-based SEEO and France-based Bolloré—are developing solid-state batteries that use high-temperature polymers as the electrolyte.
CERAMICS AT ROOM TEMPERATURE
Over the last decade, two classes of ceramics—LLZO (lithium, lanthanum, and zirconium oxide) and LGPS (lithium, germanium, phosphorus sulfide)—have proven almost as good at conducting ions at room temperature as liquids.
Toyota, as well as the Silicon Valley startup QuantumScape (which raised $100 million in funding from Volkswagen last year), are both working on deploying ceramics in lithium-ion batteries. The inclusion of big players in the space is indicative that a breakthrough might be nearer than many think.
“We are quite close to seeing something real [using ceramics] in two or three years,” says Carnegie Mellon‘s Viswanathan.
A balancing act
Batteries are already big business, and the market for them keeps growing. All that money attracts a lot of entrepreneurs with even more ideas. But battery startups are difficult bets—they fizzle even more often than software companies, which are known for their high failure rate. That’s because innovation in material sciences is hard.
So far battery chemists have found that, when they try to improve one trait (say energy density), they have to compromise on some other trait (say safety). That kind of balancing act has meant the progress on each front has been slow and fraught with problems.
But with more eyes on the problem—MIT’s Yet-Ming Chiang reckons there are three times as many battery scientists in the US today than just 10 years ago—the chances of success go up. The potential of batteries remains huge, but given the challenges ahead, it’s better to look at every claim about new batteries with a good dose of skepticism.
An employee positions a Tesla Model S automobile during a battery-pack fitting at a factory in Tilburg, Netherlands. PHOTO: JASPER JUINEN/BLOOMBERG
Investors are enthusiastic about QuantumScape, developer of an electric-vehicle battery that promises more power for less cost. If the company succeeds, Tesla could face new challenges.
One of the wildest plotlines in the great 2020 electric-vehicle rally was the late-year rise ofQuantumScape,a battery startup that has yet to report any revenue.
If investors are even close to being right about its roughly $44 billion market value, they may need to worry more about the fortunes of Tesla.
QuantumScape’s shares have soared since going public in November. The company revealed promising test results for a limited version of its “solid state” battery in early December, but otherwise the stock’s meteoric ascent has been hard to explain.
Based in San Jose, Calif., and backed byVolkswagenand Bill Gates, the company now has a market value greater thanFord.Investors have gotten used to dizzying valuations for electric-vehicle startups positioning themselves as the next Tesla. With QuantumScape, the mania has reached potential suppliers too.
Solid-state batteries have long been seen as a way of breaking through performance limitations associated with today’s electric vehicles. Like your smartphone, a Tesla orBMWi3 is powered by a battery with a liquid electrolyte that carries lithium ions back and forth between the cathode and anode during charging and discharging.
The promise of solid state is to get rid of the liquid, and with it the fire risk. Moreover, “lithium-metal” cells being developed by QuantumScape, among others, combine the lithium component with the anode, further reducing bulk and potentially delivering more power at a lower cost.
This is also critical: Electric vehicles have long been held back by the relatively high cost of batteries, which makes them more expensive than combustion-engine equivalents.
Other advantages of solid state include rapid charging and longer life expectancy. QuantumScape said in December that its cell as tested could be recharged to 80% in 15 minutes and retained more than 80% of its capacity even after 800 charges. Such numbers would make owning an electric vehicle much more similar to owning a gas-powered one today.
Many in the battery industry see solid state as the most likely technology of the future. Tesla Chief ExecutiveElon Muskis a prominent exception. Solid state wasn’t among the many developments discussed in the company’s September “battery day.” Mr. Musk told analysts on the third-quarter results call that removing the conventional anode “is not as great as it may sound” in terms of delivering space savings in the cell.
Tesla’s skepticism may also be related to its own battery technology, which would likely make it harder than for others to adapt to solid state electrolytes. Tesla uses cylindrical batteries formed from rolled cells, whereas its competitors typically favor so-called prismatic batteries, in which cells can be stacked. Because solid-state cells are more brittle than liquid ones, they will be much easier to stack than to roll.
Adapting most of today’s electric-vehicle battery factories to the new technology won’t be too disruptive, says Graeme Purdy, chief executive of Ilika, a U.K.-based solid-state company that is working with Jaguar Land Rover to ensure a smooth transition. But it might be another story for Tesla. This could be the point where the company’s batteries, which have been a competitive advantage to date, turn into a competitive disadvantage.
Tesla does have time on its side, if it needs to change tack.Toyotaprobably has the most advanced solid-state batteries today: It planned to have them powering prototype vehicles at the 2020 Tokyo Olympics, which were postponed a year, and is targeting a mass-produced model by 2025.
But the technology probably won’t be cost competitive with today’s batteries until the late 2020s at the very earliest.
QuantumScape’s investors are playing a very long game. The business plan doesn’t envisage meaningful revenues before 2026.
There is also no guarantee that the company’s solution will win out over those of Toyota and others. The test results QuantumScape announced last month were for single-layer battery cells. Private U.S. startup Solid Power is already producing multi-layer solid-state batteries in a factory in Louisville, Colo. “The manufacturing challenges get exponentially harder as you move to multiple layers,” says Mark Newman, an analyst at brokerage Bernstein who focuses on the battery industry.
The valuations of companies like Tesla and QuantumScape require investors to look far into the future and assume mass disruption to the status quo. The wrinkle is that if QuantumScape’s plan works out—a big if—Tesla itself could be one of the companies most disrupted. In 2020, investors bought almost anything related to electric vehicles. This year they need to become more discerning.