An MIT spinout is preparing to commercialize a novel rechargeable lithium metal battery that offers double the energy capacity of the lithium ion batteries that power many of today’s consumer electronics.
Founded in 2012 by MIT alumnus and former postdoc Qichao Hu ’07, SolidEnergy Systems has developed an “anode-free” lithium metal battery with several material advances that make it twice as energy-dense, yet just as safe and long-lasting as the lithium ion batteries used in smartphones, electric cars, wearables, drones, and other devices.
The battery essentially swaps out a common battery anode material, graphite, for very thin, high-energy lithium-metal foil, which can hold more ions — and, therefore, provide more energy capacity. Chemical modifications to the electrolyte also make the typically short-lived and volatile lithium metal batteries rechargeable and safer to use. Moreover, the batteries are made using existing lithium ion manufacturing equipment, which makes them scalable.
In October 2015, SolidEnergy demonstrated the first-ever working prototype of a rechargeable lithium metal smartphone battery with double energy density, which earned them more than $12 million from investors. At half the size of the lithium ion battery used in an iPhone 6, it offers 2.0 amp hours, compared with the lithium ion battery’s 1.8 amp hours.
SolidEnergy plans to bring the batteries to smartphones and wearables in early 2017, and to electric cars in 2018.
“Industry standard is that electric vehicles need to go at least 200 miles on a single charge. We can make the battery half the size and half the weight, and it will travel the same distance, or we can make it the same size and same weight, and now it will go 400 miles on a single charge,” Qichao Hu, who co-invented the battery at MIT, told MIT News. Hu is currently the CEO of SolidEnergy.
Researchers have tried to make rechargeable lithium metal batteries for decades, with no success, Hu said. “It is kind of the holy grail for batteries,” he added. Lithium metal reacts poorly with a battery’s electrolyte—a liquid that conducts ions between the cathode (positive electrode) and the anode (negative electrode). And measures to make the batteries safer usually cost its energy performance.
The SolidEnergy team used an extremely thin lithium metal foil for the anode, that is about one-fifth the thickness of a traditional lithium metal anode and several times thinner and lighter than traditional graphite, carbon, or silicon anodes—shrinking the battery size by half. The researchers also developed a solid and liquid hybrid electrolyte solution that doesn’t need to be heated to function.
The final result was a battery with the long lasting energy of lithium metal batteries, but the safety and longevity of lithium ion batteries, Hu said.
In 2012, the SolidEnergy team won the first-place prize at the MIT $100K Entrepreneurship Competition’s Accelerator Contest, and was a finalist in the MIT Clean Energy Prize. The team also placed second at the national Clean Energy Prize competition at the White House.
In late 2012, Hu was gearing up to launch SolidEnergy, when A123 Systems, the well-known MIT spinout developing advanced lithium ion batteries, filed for bankruptcy. The landscape didn’t look good for battery companies. “I didn’t think my company was doomed, I just thought my company would never even get started,” Hu says.
But this was somewhat of a blessing in disguise: Through Hu’s MIT connections, SolidEnergy was able to use the A123’s then-idle facilities in Waltham — which included dry and clean rooms, and manufacturing equipment — to prototype. When A123 was acquired by Wanxiang Group in 2013, SolidEnergy signed a collaboration agreement to continue using A123’s resources.