Advanced Materials Will Transform the Lithium Battery Market

As popular as they are, however, lithium-ion batteries have significant limitations. Storage capacity and energy density are still limited—for example, cell phones typically last only a day and electric cars cannot go much beyond 300 miles on a single charge. These batteries also rely on unstable materials that, if damaged or defective, can catch fire or explode, causing serious damage. Lithium-ion batteries also use heavy metals that are toxic and hazardous to the environment. Supplies of lithium and cobalt, two key chemical components, are also dwindling, creating price volatility. Some cobalt is also produced in less-stable countries, causing supply chain risks as well.

New Materials, Better Batteries

To meet consumer demands, researchers are working to improve the safety, efficiency, and storage capacity of rechargeable lithium-ion batteries, largely by developing new materials for the electrodes and the electrolyte, the solution that carries the lithium ions back and forth between the electrodes, creating electricity.

The most common electrode chemistries are lithium-cobalt oxide for the cathode and graphite for the anode. Not only do scientists want to improve existing battery chemistries, they want to find metal alloys and other materials that improve energy capacity and performance that are also easy to manufacture, at lower cost. Promising discoveries include:

• Lithium-sulfur batteries. Scientists at Monash University in Australia have developed a lithium-sulfur battery with the potential to double the range of an electric vehicle or power a cell phone for up to five days, on a single charge, compared to standard lithium-ion batteries. “These batteries are also extremely low-cost to manufacture, using water-based processes, and can lead to significant reductions in environmentally hazardous waste,” states lead researcher Matthew Hill.

• Lithium-silicon batteries. This alternative type of lithium-ion battery uses silicon, a plentiful and inexpensive material, for the anode, instead of graphite, boosting battery performance by up to 40% compared to standard lithium-ion batteries. Silanano is a technology start-up company that is commercializing this product, with significant investment from major automotive companies such as BMW.

• Manganese-titanium electrodes. Engineers at Yokohama National University have developed a new electrode material that boosts the performance of lithium-ion batteries. A mixture of lithium, oxygen, manganese and titanium nanoparticles allows the battery to disperse more charge over a longer time period. “Titanium and manganese are also abundant elements, meaning we can make cost-effective lithium batteries, without nickel and cobalt ions,” says researcher Naoaki Yabuuchi.

Improved Safety

Instead of using flammable liquid electrolytes, another approach is making electrolytes from more inert materials that are less likely to combust, but still carry the lithium ions back and forth efficiently.

Aqueous batteries, for example, rely on water-based electrolytes that are nonflammable and nontoxic, but historically have been unable to hold enough charge to be effective. However, researchers at Johns Hopkins University Applied Physics Laboratory have created a lithium salt-polymer electrolyte that can triple the electric potential of aqueous batteries from around 1.2 volts to 4 volts, which is comparable with commercial lithium-ion batteries. Because these batteries are also flexible and very durable, they could also be incorporated into fabrics or wearable electronics.

Electrolytes can also be made from nonflammable solid materials.

Ionic Materials, a Woburn, MA-based company, has developed an ionically conductive, fire-retardant solid polymer that can replace the liquid electrolyte in a lithium-ion battery. The material is flexible, low-cost, and durable, eliminating safety risks while boosting battery capacity and performance.

“By eliminating liquids, these new batteries will enable substantial improvements in energy density, cost, and safety, and make possible the use of chemistries that have been considered ‘the holy grail’ for batteries,” says Ionic Materials CEO Mike Zimmerman.

Moving Beyond Lithium

Researchers believe that traditional lithium-ion battery technology is nearing its limits in terms of energy density and storage capacity. Scientists are working to improve existing batteries by creating new lithium composite chemistries, as well as methods for improving storage capacity and speed. For example, scientists at WMG at the University of Warwick have developed a new process that allows current lithium-ion batteries to be charged up to five times faster by monitoring battery temperature.

Battery specialists are also developing new chemistries and nanostructures for batteries that do not involve lithium at all. For example, Rensselaer Polytechnic Institute researchers have created a potassium-based battery that performs nearly as well as a lithium-ion battery; an added benefit is that potassium is an abundant and inexpensive material compared to traditional lithium and heavy-metal chemistries.

These and other R&D advancements will help meet both industrial and consumer demands for more powerful, longer-lasting and safer next-generation batteries to power our energy needs in the future.