22 Jun 2015
Aiming to completely overhaul the lithium-ion battery industry, MIT-based scientist Yet-Ming Chiang on Monday publicly unveiled his latest startup, called 24M.
The company uses a novel battery composition based on a semi-solid material that eliminates much of the bulk of conventional lithium-ion batteries—which are typically made up mostly of inactive, non-energy-storing materials—while dramatically increasing the energy density. Chiang and 24M CEO Throop Wilder also say that they can reduce the time needed to make a battery by 80 percent and the cost by 30 to 50 percent.
After five years of research and development, 24M has raised $50 million in funding from Charles River Ventures, North Bridge Venture Partners, and its strategic partners, along with a $4.5 million grant from the U.S. Department of Energy. It has strategic partnerships with the Japanese heavy-industry giant IHI and from PTT, the formerly state-owned Thai oil and gas company, which is increasingly moving into alternative energy.
Since a 2011 paper in the journal Advanced Energy Materials previewed 24M’s technology, the company has received a large amount of press coverage for a stealth-mode startup, including articles in this publication as well as a long, adulatory profile on the website Quartz. The company calls its new battery “the most significant advancement in lithium-ion technology since its debut more than 20 years ago.”
That would be a remarkable accomplishment, with the potential to drive the electric-vehicle market to a new level and accelerate the spread of renewable energy. But 24M faces a challenge that many previous companies with promising technology have failed to solve: how to revolutionize a manufacturing industry with huge amounts of capital sunk into extensive existing capacity.
Yet-Ming Chiang is personally familiar with this quandary: he was one of the founders of A123, the lithium-ion startup that received nearly a quarter of a million dollars in funding from the U.S. government, went public in the largest IPO of 2009, and filed for bankruptcy in 2012. A123 was done in by an EV market that grew slower than expected and by its close relationship with EV maker Fisker, which itself failed in 2013 and was purchased by the Chinese auto parts company Wanxiang Group. But it also stumbled in trying to compete with more established battery makers such as LG and Panasonic.
Chiang acknowledges the dilemma: “In the last decade, there have been a lot of new lithium-ion plants built, and the EV market has not materialized to fill these factories.”
Now, energy storage demand is soaring—for vehicles, for power grids, and for residences with distributed renewable generation, such as rooftop solar arrays. Capacity in the United States is expected to more than triple this year, and rapid growth will continue through the end of the decade, according to GTM Research.
That means that demand for a less expensive, more efficient technology should be robust. But the building boom of the previous decade means there’s also excess manufacturing capacity available to supply that market. LG Chem’s plant in Holland, Michigan, which makes batteries for the Chevrolet Volt and the Cadillac ELR, currently operates at about 30 percent of capacity, according to CEO Prabhakar Patil.
And established players are already increasing their output. Mercedes-Benz parent company Daimler, for instance, announced late last year it will invest 100 million euros ($113 million) to expand its lithium-ion manufacturing capacity through its subsidiary Deutsche ACCUmotive.
Then there’s the Gigafactory. Tesla’s giant Nevada plant will produce 35 gigawatt-hours’ worth of batteries a year, dwarfing any previous manufacturing ventures for lithium-ion batteries.
Meanwhile, improvements in the manufacturing of conventional lithium-ion batteries are reducing the cost per kilowatt-hour of existing systems—even as research into next-generation chemistries, such as lithium-sulfur and lithium-air, continues at institutions around the world.
In short, 24M is attempting to transform a worldwide manufacturing industry in which established players with deep pockets are investing hundreds of millions in the expansion of existing processes. That’s a tough road even for a startup with a novel and exciting technology.
Chiang and CEO Wilder are undeterred. “This is the next great mega-market,” says Wilder. “To quote Elon Musk, the world is going to need multiple gigafactories.”
Extremely small batteries built inside nanopores show that properly scaled structures can use the full theoretical capacity of the charge storage material. The batteries are part of assessing the basics of ion and electron transport in nanostructures for energy storage. These nanobatteries delivered their stored energy efficiently at high power (fast charge and discharge) and for extended cycling.
Precise structures can be constructed to assess the fundamentals of ion and electron transport in nanostructures for energy storage and to test the limits of three-dimensional nanobattery technologies.
Nanostructured batteries, when properly designed and built, offer promise for delivering their energy at much higher power and longer life than conventional technology. To retain high energy density, nanostructures (such as nanowires) must be arranged as dense “nanostructure forests,” producing three-dimensional nanogeometries in which ions and electrons can rapidly move. Researchers have built arrays of nanobatteries inside billions of ordered, identical nanopores in an alumina template to determine how well ions and electrons can do their job in such ultrasmall environments.
The nanobatteries were fabricated by atomic layer deposition to make oxide nanotubes for ion storage inside metal nanotubes for electron transport, all inside each end of the nanopores. The tiny nanobatteries work extremely well: they can transfer half their energy in just a 30 second charge or discharge time, and they lose only a few percent of their energy storage capacity after 1000 cycles. Researchers attribute this performance to rational design and well-controlled fabrication of nanotubular electrodes to accommodate ion motion in and out and close contact between the thin nested tubes to ensure fast transport for both ions and electrons.
This work was performed at the University of Maryland and was supported by the Nanostructures for Electrical Energy Storage (NEES) Center, an Energy Frontier Research Center funded by the DOE Office of Science, Office of Basic Energy Sciences.
- Chanyuan Liu, Eleanor I. Gillette, Xinyi Chen, Alexander J. Pearse, Alexander C. Kozen, Marshall A. Schroeder, Keith E. Gregorczyk, Sang Bok Lee, Gary W. Rubloff. An all-in-one nanopore battery array. Nature Nanotechnology, 2014; 9 (12): 1031 DOI: 10.1038/nnano.2014.247
- Paul V. Braun, Ralph G. Nuzzo. Batteries: Knowing when small is better. Nature Nanotechnology, 2014; 9 (12): 962 DOI: 10.1038/nnano.2014.263
A new semiliquid battery developed by researchers at The University of Texas at Austin has exhibited encouraging early results, encompassing many of the features desired in a state-of-the-art energy-storage device. In particular, the new battery has a working voltage similar to that of a lithium-ion battery, a power density comparable to that of a supercapacitor, and it can maintain its good performance even when being charged and discharged at very high rates.
The researchers, led by Assistant Professor Guihua Yu, along with Yu Ding and Yu Zhao, at UT Austin, have published their paper on the new membrane-free, semiliquid battery in a recent issue of Nano Letters. The researchers explain that the battery is considered “semiliquid” because it uses a liquid ferrocene electrolyte, a liquid cathode, and a solid lithium anode.
“The greatest significance of our work is that we have designed a semiliquid battery based on a new chemistry,” Yu told Phys.org. “The battery shows excellent rate capability that can be fully charged or discharged almost within one minute while maintaining good energy efficiency and reasonable energy density, representing a promising prototype liquid redox battery with both high energy density and power density for energy storage.”
The battery is designed for applications in two of the biggest areas of battery technology: hybrid electric vehicles and energy storage for renewable energy resources.
As shown in the figure above, the battery’s high power density (1400 W/L) and good energy density (40 Wh/L) put it in the uniquely favorable position of combining a power density that is as high as that of current supercapacitors with an energy density on par with those of state-of-the-art redox flow batteries and lead-acid batteries, though slightly lower than that of lithium-ion batteries. This combination is especially attractive for electric vehicles, where the power density corresponds to top speed and the energy density to the vehicle’s range per charge.
The researchers also report in their paper that the new battery has a high capacity (137 mAh/g) and a high capacity retention of 80% for 500 cycles.
The researchers attribute the battery’s good performance in large part to its liquid electrode design that enables its high rate capability, which is basically a measure of how fast the battery operates. The ions can move through the liquid battery very rapidly compared to in a solid battery, and the redox reactions in which the electrons are transferred between electrodes also occur at very high rates in this particular battery. For comparison, the values used to measure these rates (the diffusion coefficient and the reaction constant) are orders of magnitude greater in the new battery than in most conventional flow batteries.
Although the battery looks very promising so far, the researchers note that more work still needs to be done, in particular regarding the lithium anode.
“The potential weakness of this battery is the lithium anode in terms of long-term stability and safety,” Yu said. “More advanced lithium anode protection is required to fully suppress self-discharge. We suppose that other metals like zinc and magnesium may also function as the anode for such a battery as long as the electrolyte compatibility is resolved. We also expect that other organometallic compounds with multi-valence-state metal centers (redox centers) may also function as the anode, which eventually would make the battery fully liquid.”
In the future, the researchers plan to test the long-term durability of the battery, especially its lithium anode, under realistic operating conditions. In addition, the researchers want to find a way to increase the solubility of ferrocene in order to further increase the energy density to compete with current lithium-ion batteries while maintaining its very high power density.
More information: Yu Ding, et al. “A Membrane-Free Ferrocene-Based High-Rate Semiliquid Battery.” Nano Letters. DOI: 10.1021/acs.nanolett.5b01224
Tesla is launching the home battery business partly because it’s already making vehicle batteries—and as a result it can benefit from the economies of scale that come from making both. Another reason is that the market for storage is expected to grow in concert with the use of solar power. Tesla needs both electric vehicles and solar power to boom if it hopes to fulfill the projected output from a vast $5 billion battery “gigafactory” it’s building in Nevada.
“The obvious problem with solar power is that the sun does not shine at night,” Tesla CEO Elon Musk said at the unveiling of the new batteries at the company’s design studio in Hawthorne, California, yesterday. “We need to store the energy that is generated during the day so you can use it at night.”
A number of solar companies now offer batteries to accompany their solar panels (see “Solar Power, and Somewhere to Store It”). Although just a tenth of a percent of U.S. homes now get power from rooftop solar panels combined with energy storage, such systems could account for 3 percent of homes by 2018, according to Greentech Media Research.
Tesla’s residential battery, called Powerwall, will be available in several months and will come in two sizes, a seven-kilowatt-hour battery system that costs $3,000 and a slightly larger 10-kilowatt-hour system for $3,500. The larger battery would keep an average-sized home running for a day. It is unclear what the cost of installation would be.
Tesla expects that many sales will come from commercial customers who pay a variable rate of electricity over the course of a day based on demand. Such customers already see significant reductions in their energy bills by drawing on stored electricity during periods of peak energy demand.
In the near term, the market for home energy storage will depend on how states regulate homeowners’ ability to buy and sell electricity. Net metering, currently available in 43 states, allows residential customers to sell excess generation back to their utility company at retail rates. The policies are being challenged by utility companies that say it undermines their ability to recoup grid infrastructure costs. But as long as net metering continues, consumers will have little need to buy an energy storage system because they can sell the excess solar power they generate rather than store it, says Jay Stein, an analyst with energy consulting company E Source. “I don’t see any financial payoff for them to buy batteries,” he says.
Most utilities that offer net metering, however, also allow residential customers to buy and sell electricity at rates that vary throughout the day based on demand. Battery storage would allow such people to maximize the value of the electricity they sell back to the utility.
“There are some arbitrage values emerging,” says Karl Rábago, executive director of the Pace Energy and Climate Center in White Plains, New York. “If I could export selectively, using a storage device, I might beget higher value for my generation.”
Home energy storage will make more sense in the years to come. Residential and commercial solar-plus-storage systems will offer a clear cost advantage over electricity from the grid throughout the United States by 2030, according to a recent report by the Rocky Mountain Institute, an energy research and consulting group.
Tesla’s Nevada gigafactory, which it’s building with Panasonic, will have an annual production capacity of 35 gigawatt-hours by 2020, more than all the lithium-ion batteries produced globally in 2013.
Such a large investment in what is still a niche market is risky, but Tesla claims that the new factory will cut battery costs by 30 percent when it begins operations, as early as 2016. Tesla’s biggest challenge will likely be filling enough orders for the output. By 2020, the plant will be able to produce enough batteries for half a million electric vehicles per year. Last year, Tesla sold around 20,000 cars.