The jump from 2,600 milliampere-hours to 3,000, seen in the upgraded Samsung Galaxy S7, led reviewers to note a huge difference in battery life. Now industry watchers are anticipating the S8 may see even more dramatic changes that extend battery life for up to a week, thanks to a nanotechnology breakthrough by South Korean researchers. Professor Gyeong Man Choi of the Pohang University of Science and Technology and his student Kun Joong Kim have developed a miniaturized solid oxide fuel cell (SOFC) that represents a revolutionary improvement over today’s lithium-ion batteries.
This exciting development is just one example of how nanotechnology is revolutionizing smartphone battery life. Here’s a look at some of the ways researchers are applying nanotechnology to super-charge smartphone batteries:
Shrinking Battery Architecture
Nanotechnology is helping researchers understand the causes of battery decay as well as how to prevent it. Texas A&M researcher Sarbajit Banerjee has discovered that trapped electrodes contribute to the breakdown of lithium-ion batteries. You can visualize the flow of electrons through a battery as flowing water, Banerjee explains. As this water flows, some electrons start to get trapped by lithium ions, forming charged puddles. These puddles accumulate over time, making batteries less efficient after each recharge, until eventually they are too unstable for practical use.
Banerjee says that one way to slow this decay is by using nanotechnology to shrink battery architectures. This can accelerate the uptake and release of lithium ions, reducing the formation of charge puddles.
Making Electrode Surface Area Bigger
Another team financed by Samsung is taking a different approach to improving batteries. Israeli company StoreDot has accelerated battery recharging by coating electrodes with small artificial protein “nanodots” to build “nanotubes.” Covering electrodes in nanodots increases their reactive surface area, multiplying their capacity. In 2015, StoreDot demonstrated that a battery charger using nanotubes could recharge a Samsung smartphone in 26 seconds. Samsung and StoreDot are now working on applying this technology to rapidly recharge electric car batteries, with advances in car battery research doubling to advance smartphone batteries at the same time.
A Chinese-funded Czech company, HE3DA, is doing research along similar lines. HE3DA’s approach focuses on using nanotechnology to transform flat electrodes into more three-dimensional shapes with more surface area. This allows the electrodes to absorb more energy during the charging process, increasing charging capacity. Making an electrode ten times larger would enable ten times more energy to be stored per charge.
Building Better Electrodes
Where some nanotechnology researchers are trying to increase electrode surface area, researchers like Gyeong Man Choi are trying to build better electrodes. Traditionally, silicon has been used to build supporting structures in small oxide fuel cells, but this yields low durability due to a mismatch between the thermal properties of silicon and battery electrolyte fluids. Gyeong’s method uses nano-porous stainless steel, which is much stronger, more thermally durable and highly stable during oxidation/reduction reactions. By combining this nano-steel with electrodes of minimal heat capacity and thin-film electrolytes, Gyeong’s team has been able to improve battery performance and durability. The result is a smartphone that only needs to be charged once a week.
Samsung has also experimented with growing graphene, a nano-thin form of carbon, over silicon anodes to preserve their shape. Other researchers at Stanford University have developed a method that uses silicon nanowires, which can expand and contract to absorb lithium ions and release them. Combining these nanowires into nanoclusters forms an egg-like protective shell around silicon nanoparticles, preventing reactions that cause anode decay. The nanowires can also be shielded in graphene to allow greater power absorption. The resulting battery can store up to 40 percent more energy than lithium-ion batteries and retain 97 percent of its capacity after 1,000 charges. Stanford’s researchers are also experimenting with using lithium metal instead of silicon, as well as using titanium dioxide shells to encase sulfur in cathodes.