What’s beyond lithium-ion?

ESE MarApr15 Pg12 Mouser 1Mouser Electronics’ Landa Culbertson takes a look at some of the battery concepts set to power ahead in the future.

Mobile technology hinges on the availability of batteries to support it. Lightweight, cost-effective, rechargeable and providing higher energy density by far compared to the next commercial battery chemistry, lithium-ion (Li-ion) is the workhorse and standard for powering today’s mobile devices.

Developed in the 1970’s, Li-ion battery technology is however, nearing its theoretical limits and is unable to keep pace with advances in mobile technology. Not only is this demonstrated by the constant need to charge mobile devices, but also by the latest innovations to circumvent the issue and provide improved run-time, including wireless charging and mobile battery cases.

The hunt for a better battery is becoming urgent, with battery limitations gating not only consumer electronics, but also the electric car industry and related clean energy initiatives. Consequently, there has been a flurry of activity to develop new battery technologies and here are a few of the future concepts set for growth.

Tin nanocrystal Li-ion batteries

Batteries convert chemical energy into electrical energy by sharing a common carrier electron. Today’s Li-ion batteries generate power by sending Li ions from the negative electrode (anode) to the positive electrode (cathode), and the reverse during charging. The electrodes are typically made of cobalt, graphite, manganese, or nickel and do not absorb all of the Li ions. Tin is a better electrode, but tin crystals can become up to three times bigger when absorbing ions, and shrink when releasing the ions, much like a sponge. To handle the volumetric change, scientists at the Laboratory of Inorganic Chemistry at ETH Zurich and Empa are developing a nanomaterial made of tiny tin crystals which can effectively absorb and release the Li ions, thus doubling the energy capacity of the battery.

Metal-air batteries

The metal electrodes of batteries in the metal-air category react with oxygen in the air, instead of a liquid, to produce an electrical current. The most promising materials for the electrode appear to be Li and sodium, but aluminium and zinc have also been researched. In fact, zinc-air batteries, such as Renata’s ZA312-0% 40 zinc-air hearing aid battery, are already available.

Although the Li-air battery is still in its infancy, the technology holds the most promise, with five to ten times higher theoretical specific energy than Li-ion batteries. It is particularly attractive to the electric car industry. The high specific energy of Li-air batteries translates to 1,000 miles of range, compared to the existing average of 125 miles on Li-ion batteries.

Sodium-air batteries have a lower theoretical energy capacity than Li-air, but are more stable and easier to build. Tests on sodium-air batteries have also shown that they may present a higher practical energy storage capacity than Li-air.

Liquid metal batteries

Start-up, Ambri, has developed a battery that uses a molten salt electrolyte sandwiched between two layers of liquid metal. The difference in composition between the liquid-metal electrodes, one low-density negative and the other high-density positive, creates a voltage. Ambri is targeting storage applications in the power grid to make the energy system more efficient.

Other new battery concepts including Li-sulpher and sugar-powered biobatteries are among the many concepts in development. It’s a race to see which technology will succeed Li-ion, but no matter what, the consumer is sure to benefit.