As time progresses, nearly all of the components in the personal electronic devices available for purchase rapidly transform, as advancements in display, camera, and processor technology enable an ongoing improvement in the user experience. One exception to this rule, however, is their batteries — lithium-ion battery technology has remained basically unchanged for several years, as the technology seems to approach the limits of the density of energy storage. Batteries composed of different materials, including graphene and lithium-metal, offer promising developments in the size and capacity of batteries for mobile devices, but technology involving these materials has not yet progressed to the point of safety and commercial viability. However, scientists around the world are dedicated to discovering breakthroughs in the field of battery technology, and one such breakthrough may have begun recently at the Pacific Northwest National Laboratory in Washington.
In this laboratory, scientists have pinpointed the cause of one of the greatest impediments to the development of lithium-metal batteries, which is the growth of microscopic needle-like structures within the material of the batteries, leading to short circuits, battery failure, and even fires. Though these structures can form in both lithium-ion and lithium-metal batteries, they are much more prevalent in the latter type of battery, halting the widespread adoption of lithium-metal in battery-powered devices. While it’s too soon to assert that this research shows the commercial and practical viability of lithium-metal battery technology, the research represents a significant advancement in the field, as it provides scientists around the world with information that could help them refine and perfect the technology.
The scientists discovered the cause of the needle formation by taking advantage of two high-resolution microscopes, an atomic force microscope and an environmental transmission electron microscope, which they used together to observe the chemical reactions that produced the needles, also known as dendrites. With this technique, they found that dendrites begin when lithium ions started to gather, or “nucleate,” on the surface of the anode. (An anode is the positively charged electrode by which electrons leave a device.) The team compared the development of these dendrites to the growth of a stalagmite on the floor of a cave.
Instead of simply suppressing the growth of dendrites, the team wanted to find the root cause of their growth and eliminate it. As such, the scientists experimented with the mix of electrolytes in the batteries to determine which ingredients led to the development of dendrites. They found that one ingredient in particular, ethylene carbonate, directly correlates with dendrite and whisker growth, and found that adding some ingredients, like cyclohexanone, prevented their growth. While ethylene carbonate enhances battery performance and is currently considered an indispensable ingredient in lithium batteries, it also leaves the battery vulnerable to damage. As such, more research is necessary to determine what ingredients, if any, can replace ethylene carbonate in potential lithium-metal batteries of the future. That being said, these initial findings may very well clear the path for the development of lithium-metal batteries and their implementation in battery-operated devices generally.
Although this research breathes life into the possibility of higher-capacity batteries in our devices, for the foreseeable future we will continue to rely on rechargeable lithium-ion batteries for the vast majority of applications. However, lithium-ion technology has proven to be a tremendous advancement in energy-storage technology, so much so that the researchers responsible for pioneering these devices recently won a Nobel Prize. Though the products have been on the market since 1991, they have since “laid the foundation of a wireless, fossil-fuel-free society, and are of the greatest benefit to humankind,” according to the Nobel committee.