IMPROVING THE BATTERY IN THE TESLA MODEL S ELECTRIC CAR Credit: C&EN/YouTube

Elon R. Musk, the billionaire founder of PayPal and chief executive officer of the California-based car company Tesla Motors, took to an open-air stage in London recently for the U.K. launch of his new all-electric car, the Model S. During a rock-concert-like event he handed over the keys to Britain’s first Model S purchasers and told a crowd of customers, partners, and the press that anything combustion engine cars can do, the Model S can do too.

And so it can. The Model S, a stylish plug-in electric sedan, emits little more than a gentle hum as it accelerates to 60 mph in 4.2 seconds, and it will keep going without a recharge for 300 miles. What Tesla has achieved is remarkable given that most competing electric cars have a range of less than 100 miles.

But if that is the fundamental flaw of other electric cars, Tesla’s Model S has a flaw of its own: its high cost. Owing in large part to an expensive battery, Tesla is selling its 300-mile car for $80,000 in the U.S. and even more overseas, putting it out of reach of all but the wealthiest customers.

More than 150 battery developers across the globe think they have the know-how to solve the cost-performance challenge with more energy-dense materials. Like Tesla, many of the firms are testing variations on the lithium-ion battery, best known as the power source for laptops and cell phones. Others are developing batteries with cheaper ions, such as sodium, or from difficult-to-handle lithium metal and sulfur electrodes, which in theory offer a higher energy density than standard lithium-ion batteries.

Energy density, also known as specific energy, is the amount of energy stored per unit of volume or mass. Higher energy density means less raw material is required for the same available energy, making the battery potentially lower cost and lighter.

Although Tesla may have found a niche in the luxury car market, there is a risk that too many battery developers are chasing a mass electric car market that may never develop. With gasoline an order of magnitude more energy dense than electric car batteries and private financing for the sector scarce, analysts predict that many battery firms will go bankrupt in the next few years.

GOING THE DISTANCE Credit: Tesla

In their efforts to solve the technological challenge, battery developers consider the cathode to be the key to battery performance. As ions move from the anode through electrolyte and across a separator to the cathode, they generate an electric current. The more ions that the cathode can hold, the more energy the battery can store and release. Formulating novel electrolytes and replacing the graphite anode with new materials such as graphene or silicon are also options that can enhance a battery’s energy density and overall performance.

In association with the Japanese electronics giant Panasonic, Musk has extended the distance Tesla cars can travel on a single charge by developing a lithium-ion battery with cathodes made from a lithium-nickel-cobalt-aluminum formulation.

At a reported 240 Wh/kg, the energy density of Tesla’s battery is far higher than that of the nickel metal hydride (NiMH) battery used in Toyota’s Prius electric-gasoline hybrid. It is also slightly higher than that of the lithium-ion manganese spinel battery used in General Motors’ Volt hybrid and the nickel-manganese-cobalt (NMC) battery reportedly used in Nissan’s all-electric Leaf. To extend the range of the Model S beyond the competition, Tesla has installed a bigger battery: Hidden under its floor is a battery about the size of a double mattress and weighing 670 kg, about 1,500 lb.

Tesla says the battery for its Model S accounts for less than half the cost of the car. If battery technology firms can reduce battery costs by two-thirds, the electric car industry will begin to compete on price with the combustion-engine-based incumbent.

Cosmin Laslau, an analyst with Lux Research, sees this happening slowly. He predicts the electric vehicle battery market will be worth about $3.2 billion in 2023 from the sale of 230,000 vehicles, up from about 90,000 last year. The plug-in car battery market currently is worth about $2 billion. More than 80 million conventional cars are sold worldwide every year. “The window of opportunity may be closing for some older technologies like NiMH, but lithium-ion keeps growing in new directions,” Laslau says.

Musk is optimistic that even in the next few years Tesla will reduce battery costs for its cars by one-third, largely through improvements in manufacturing efficiencies and scale.

But not all automakers are interested in electric cars. Wolfgang Epple, director of research and technology for Jaguar Land Rover, remains skeptical about major battery performance improvements in the near term. The Tesla Model S battery has an energy density “equivalent to 7 L [shy of 2 gal] of fuel,” Epple told an audience recently during a lecture at London’s Imperial College. “This is currently the big inhibitor of electric cars,” he said. “I am too old to ever experience battery content the same as fuel. I fear it will take 100 or even 200 years.”

Although battery developers say they are making headway with increasing batteries’ energy density, financing in the sector has become scarce and several battery companies, such as U.S. lithium iron phosphate (LFP) battery developer A123 Systems, have gone bankrupt.

PLUGGED IN [+]Enlarge Credit: Tesla

Many more battery developers could be about to experience tougher operating conditions. Tesla and Panasonic say they plan to invest $5 billion to build a lithium-ion battery factory in the western U.S. that would have capacity to build battery power systems for 500,000 cars per year by 2020, much more than the world’s electric car market today. The firm plans to sell some of the batteries from the proposed plant to other automotive companies.

“In lithium-ion battery manufacture there will be a bloodbath,” the consulting firm IDTechEx warned in a recent report. “The handful of annual bankruptcies today will rise to tens a year. The industry will shake down to something like five volume players and perhaps 50 niche players.”

Some leading battery chemistry firms, such as the German chemical maker ­Evonik Industries, have already pared their role in the business. Evonik recently sold its shares in a lithium-ion battery cell joint venture and a finished battery joint venture to the carmaker Daimler, its partner in the start-ups. Evonik’s activities in plug-in electric cars now focus on the development of electrode materials, separator membranes, and electrolytes.

Swiss chemical company Clariant is considering an exit from LFP battery materials. In 2010, Clariant opened a 2,500-metric-ton-per-year LFP plant in Quebec at a cost of about $80 million, but it has become a loss-making business for the firm.

“The importance of LFP has decreased in the past few years,” acknowledges Clariant CEO Hariolf Kottmann. “Today there is only a special, very small market.” Kottman plans to decide later this year whether to divest or close the business, or refocus it on markets such as electric buses where LFP technology is used.

In contrast to Clariant, BASF offers battery makers a suite of materials, including electrolytes and various metal oxide and phosphate compounds for cathodes. The German company sees a strong future in the business. BASF’s cathode materials range from the established LFP and NMC technologies through to what the firm describes as the more experimental lithium metal-sulfur. In the latter batteries one of the challenges is that lithium nodules have a potential to build up and pierce the battery separation membrane with catastrophic consequences. Such factors in the past have encouraged car manufacturers to stick with safer but less energy-dense forms of lithium-ion.

Andreas Fischer, head of battery materials research for BASF, predicts that the firm’s novel high-energy and high-voltage materials will enable customers to boost the energy density of today’s state-of-the-art electric car batteries by 50% in the next few years and by another 100% within the next 10 years.

Nickel-rich cathode compounds offer potential for high energy density but require sophisticated electrolyte chemistry because of the sensitivity of the material. “Here we are making tremendous progress,” Fischer says.

BASF has a stake in the U.S. lithium-sulfur battery firm Sion Power and is also developing materials in this field. This is a next-generation project that will lead to the introduction of a lithium-sulfur battery after 2020, Fischer says. Other approaches BASF is pursuing include double-layered oxide materials. It’s also investigating how to exchange carbon anodes for silicon compounds by developing suitable electrolyte and binder systems.

More than 100 BASF research scientists are involved in the effort to develop battery materials in the U.S., Germany, China, and Japan, Fischer says. The company recently opened an R&D lab for electrolytes and anodes in Amagasaki, Japan.

SEARCHING FOR ENERGY DENSITY

BASF says it is on course to invest several hundred million dollars in the business between 2011 and 2016 and generate annual sales in excess of $500 million by 2020. The majority of its sales today are in consumer electronics such as cell phones, but that is set to switch to automotive batteries in the next few years, according to the firm.

“Clearly it is picking up in the automotive industry,” says Phillip Hanefeld, director of strategy for BASF’s battery materials business. “I am already sharpening my pencil” in anticipation of capacity expansions as the market for electric car batteries builds, he says.

Although the new technologies that BASF is developing, such as lithium-sulfur, hold the promise of far higher energy density, these are not materials that even Musk, a serial risk taker, is considering using in his cars anytime soon. Instead, he’s banking on being able to steadily improve the energy density of Tesla’s lithium-ion batteries by about 8% annually in the coming years.

“Lithium-sulfur is potentially a good solution for aircraft but not for cars,” Musk tells C&EN. “Potentially there are improvements in lithium-sulfur that could help. But it also has a charge rate and power density issue, so you can’t charge it and discharge it very fast.

“Battery chemistry is a very, very tricky thing,” Musk says. “It’s remarkable how many so-called breakthroughs you read about turn out to be nonsense.” Asked if he will stick with lithium-ion for the foreseeable future, Musk pauses for a moment. “I really don’t know anything better,” he says.

Along with giants such as BASF, some of the smallest start-up technology firms think they have that something better. Companies such as England-based Faradion, with just 10 employees and a few million dollars in funding, say they are already well advanced in developing chemistry that will provide high battery performance at low cost.

Faradion is developing a sodium-ion battery that it says is on track to be one-third cheaper than lithium-ion batteries for the same performance. The firm’s latest tests for full sodium-ion battery cells show an energy density of about 140 Wh/kg, similar to lithium-ion batteries. But improvements in materials, compound porosity, and electrode thickness, among other factors, will push that figure within the next few years to about 200 Wh/kg, according to Jerry Barker, a veteran battery materials chemist and the head of R&D for Faradion.

A key benefit for companies mass producing lithium-ion batteries is that Faradion’s sodium-ion technology is a drop-in replacement, Barker says. “No one working on the factory floor would even notice the difference if you swapped the lithium-ion battery for our sodium-ion battery,” he contends.

Another key player in sodium-ion is Sumitomo Chemical. But having studied the Japanese firm’s patents, Barker claims Faradion has created a new battery system, whereas Sumitomo has merely modified an old one. “In terms of material structure, sodium gives more freedom than lithium because of the larger size of the ion, so we thought there were better materials that we could work with,” he says.

INNER WORKINGS [+]Enlarge

Faradion’s strategy is to demonstrate its sodium-ion technology first in products where the lead time is short and brand-risk is limited, such as electric bikes. But after giving a presentation in June at a key battery meeting, Faradion is now attracting the attention of major car companies, says CEO Chris Wright.


The California-based battery maker Envia Systems learned the hard way, though, that auto industry attention doesn’t always pay off. GM, a car company that many battery start-ups would love to work with, invested in Envia in 2010, only to have a falling out with the company three years later.

Envia’s battery builds on a lithium-rich cathode technology licensed from Argonne National Laboratory. The company claims to have built on that technology and developed proprietary lithium-ion cathode compositions featuring nickel, cobalt, manganese, and lithium-manganese oxide with a high energy density validated at the R&D level. But it subsequently failed to meet the performance milestones GM set for powering a car for 200 miles on a single charge. GM canceled the deal with Envia last summer.

Envia continues to develop the technology without GM. In February it was awarded a Department of Energy grant as part of a consortium developing an electric car with a multifunctional chassis.

Taking on what is arguably even more complex chemistry than is involved in a lithium-ion battery, a handful of companies, including Sion and English start-up Oxis Energy, consider that a lithium metal anode and a sulfur-carbon cathode are the way to solve the battery challenge. Lithium-sulfur batteries have a theoretical energy density of 2,735 Wh/kg—almost five times that of traditional lithium-ion batteries.

“We are very confident that in the next few years lithium-sulfur will become competitive on price with lithium-ion,” Oxis CEO Huw Hampson-Jones says. “We are now on the cusp of product commercialization. Even today the bill of materials for us is much, much more cost-effective than lithium-ion, but what we need is volume.”

In a partnership with Lotus Engineering, Imperial College, and England’s Cranfield University, Oxis has begun developing a lithium-sulfur battery with a target energy density of 400 Wh/kg. The collaboration, which is funded partly by the U.K. government, aims to achieve its goal by late 2016.

Oxis is working with two major chemical companies to make improvements in several areas, including novel chemistry to boost the conductivity of the sulfur. Oxis is part-owned by the South African chemical giant Sasol, which injected $24 million into the start-up last year and is helping scale up the manufacturing process. It also has a partnership with France’s Arkema around the optimization of materials technology.

Hampson-Jones is confident his firm has solved the potential problem of thermal runaway, which has scared car manufacturers away from lithium-sulfur ­batteries.

ON A ROLL [+]Enlarge Credit: BASF

Oxis’s solution has been to create a stable battery featuring a passivation layer and an electrolyte with a flash point above 140 ºC for a battery operating at about 80 ºC. This makes it safer than lithium-ion, Hampson-Jones argues. Improvements to the technology have led to a “sea change in perception” among car industry executives about the material compared with a couple of years ago, he says.

Looking perhaps several years ahead, lithium-air and lithium-water batteries may also emerge. IBM is working on Battery 500, a project to develop a lithium-air battery with an energy density of about 900 Wh/kg. Instead of more traditional anodes and cathodes, the lithium-air battery would use an encapsulated lithium metal anode and an “air cathode.” The oxidation of lithium at the anode and reduction of oxygen at the cathode induces current flow.

IBM says it’s still early days for lithium-air, and the firm isn’t looking to commercialize its technology until after 2020. “The current electrolytes, which are organic solvents, are not yet stable enough for practical use,” says Winfried Wilcke, senior manager for nanoscale science and technology at IBM. Factors that IBM has to overcome include preventing the anode from reacting with the electrolyte. “Much future research will focus on alkali-metal cells, which can use untreated air, but this research is at the very early stage,” Wilcke says.

IBM’s efforts add to an already bewildering array of battery chemistries under development. “Blended cathodes take this customization even further,” Lux Research’s Laslau says, “with elemental compositions tuned for high power, high energy, or a compromise thereof.”

Battery companies are promising a lot—via many different chemistries—but automakers that need to offer dependable vehicles are understandably cautious about latching onto any supposed next big thing. Given the lack of breakthroughs so far, battery firms may have themselves to blame if they are unable to gain the full trust of car companies in their fledgling technologies.

“Every time someone says they have a breakthrough battery I say, ‘Great, send us a sample,’ ” Tesla’s Musk says. “But they never do, or they do and it turns out to be false claims.”