What will it take to drive electric vehicles into the mainstream? If the answer is cost and performance parity with conventional vehicles, it only means one thing: We need better batteries. Only through transformative battery breakthroughs can electric vehicles achieve their full oil displacement potential.
Unleashing the potential of the lithium-ion battery is about more than incremental increases in energy density. Stabilizing the lithium, managing thermal regulation, and discovering new cathode and anode chemistries are at the heart of improving this power system.
The most significant battery breakthroughs of recent years dramatically reduce charging time, increase range, and offer additional performance benefits. It’s essential to bear in mind that these technologies are not yet commercially available—they have yet to bridge the “valley of death” between development and commercialization.
But at the same time there is reason for optimism. After all, it only takes one commercialized technology to revolutionize the marketplace. Here are a few technologies that could do just that.
1) Lithium Sulfur
In June 2013, Oak Ridge National Labs reported a breakthrough in Lithium Sulfur batteries that are four to eight times more energy dense than lithium-ion batteries. The batteries offer a doubling of range when compared pound-for-pound with current lithium-ion batteries, and only see marginal performance degradation even after being charged more than 1,500 times. Another advantage is that sulfur is abundant and virtually free.
When the breakthrough was announced in 2013, E&E reported that the key to the breakthrough was using a liquid electrolyte:
“Scientists have been chasing the potential of lithium-sulfur batteries as a long-lasting, large-scale commercial energy storage option for decades, but with little success. In using a liquid electrolyte, as in a lithium-ion battery, the sulfur batteries could effectively conduct ions but would prematurely break down.
“By completely changing the battery design, ORNL researchers were able to switch from liquid to solid electrolytes and eliminate the issue of sulfur dissolution. Liang called the development ‘game-changing.’
’In the past, we had no way to make it work; now we have the way, and we showed that this is possible with this new material and this new design,’ he said. ‘Now battery designers, manufacturers and researchers can look into this new system, and based on the material we discovered, they can design a new series of batteries for different applications.’”
It is currently unclear how soon lithium sulfur batteries will be ready for market penetration. However, it is expected that we will see lithium sulfur battery technology incorporated into personal electronics before they are applied as a fuel source for electric vehicles.
2) Stabilizing Lithium: The Holy Grail
A team of Stanford University researchers claim to have discovered the “holy grail” in lithium-ion batteries—a way to stabilize lithium such that it can be built into the anode of batteries rather than only the electrolyte, as is currently the standard in today’s batteries.
Although lithium anodes have much higher energy densities than the graphite or silicon that are currently the industry standard, they are inherently too reactive with the lithium electrode, and are not used for safety and performance reasons. In current technologies, when a lithium anode is charging, the lithium in the anode will expand and create fissures, and form dendrites or hairlike protrusions that emerge from the anode and short-circuit the battery. Lithium anodes are also highly chemically reactive with the lithium electrolyte, and can overheat to the point of fire or even explosion.
The solution developed at Stanford involves coating the lithium anode with a protective layer of tiny carbon domes. These domes, called nanospheres, form a flexible honeycomb-like shield over the anode. The coating, only 20 nanometers thick, is strong and flexible enough to move up and down as the anode expands and contracts during the battery’s charge-discharge cycle, but doesn’t compromise the energy flows between cathode, anode, and electrode.
According to the team at Stanford, which is working with former Energy Secretary Stephen Chu, lithium has the highest potential for greater energy density in the battery anode, and the new technology is robust after hundreds of cycles. They believe this development will enable cars to cost $25,000 at initial purchase with a range of 300 miles per charge—a possibility that would put EVs with initial cost and performance parity with internal combustion engines.
3) Nanotechnology and Microbatteries
Researchers at the University of Illinois at Urbana Champaign announced in April that they had developed super-powerful microbatteries as small as a few millimeters in size, with storage capabilities many orders of magnitude greater than current batteries. According to lead researcher William King, “This is a whole new way to think about batteries. A battery can deliver far more power than anybody ever thought. In recent decades, electronics have gotten small. The thinking parts of computers have gotten small. And the battery has lagged far behind. This is a microtechnology that could change all of that. Now the power source is as high-performance as the rest of it.”
But how does it work? In short, the batteries utilize micro-sized anodes and cathodes to store and release amounts of energy many orders of magnitude greater than current technology. Currently, energy storage systems are divided into those that release power tremendously quickly—such as capacitors—but only store a small amount. Fuel cells and batteries store larger amounts of energy, but release them slowly over longer periods of time. These new batteries are capable of storing thirty times as much energy and charging “1,000 times faster than competing technologies.” The technology is said to be so groundbreaking that a cell phone could be used to jump a car.
The research team reports that they are currently working with systems integrators to commercialize their technology, and are hoping the first models will be available to consumers within 1-2 years. That’s an ambitious timeline, but if this battery technology enters the electric vehicle space, it could shatter current conceptions about the limitations of electric vehicle technology.
4) Tesla’s Metal Air
There is also the “metal air” battery—Tesla received a patent for a specific application of this battery as a secondary power source in late 2013. This exciting technology uses free-flowing oxygen as the cathode, eliminating the need for an expensive and heavy cathode cell. The battery’s primary advantage is an extremely high energy storage-to-weight ratio. According to battery guru Venkat Sninivasan, the theoretical energy density of a metal air battery is comparable to gasoline.
However, drawbacks remain, such as high costs and a potentially poor life cycle. Tesla’s primary interest in the metal air battery is using it as a backup range extender, similar to the gasoline tank in a plug-in hybrid. This version, of course, would still provide all-electric power. Market strategists believe that Tesla might be waiting on a breakthrough in metal air technology, and that the company sought the patent in anticipation of this development.
5) Thermal Batteries
While the first four developments we mentioned will take a few years at least before they are commercially viable, breakthroughs in thermal management could impact battery technology in the near term. MIT’s Technology Review reports on the development of a heating and cooling system that almost eliminates the drain on the battery. Vehicle heating and cooling systems can decrease battery range by up to 30 percent, and the impact is more severe in cold weather (think about how your phone’s battery life plummets in sub-zero external temperatures). According to MIT, the new system almost eliminates the drain caused by these systems through the following function:
“In the system, water is pumped into a low-pressure container, evaporating and absorbing heat in the process. The water vapor is then exposed to an adsorbant—a material with microscopic pores that have an affinity for water molecules. This material pulls the vapor out of the container, keeping the pressure low so more water can be pumped in and evaporated. This evaporative cooling process can be used to cool off the passenger compartment.
“As the material adsorbs water molecules, heat is released; it can be run through a radiator and dissipated into the atmosphere when the system is used for cooling, or it can be used to warm up the passenger compartment. The system requires very little electricity—just enough to run a small pump and fans to blow cool or warm air.”
These technologies may not be commercially available next month, but they certainly seem promising. Conclusion? Today’s electric vehicles and batteries are just the beginning.