The University of Maryland has rolled out an innovative solid lithium battery, which, with the size of only a stamp, consists of millions of 3D micro-batteries.

Despite its minuscule size, each 3D micro-battery has sufficient surface area to accommodate nano-battery layers, resulting in satisfactory energy and power density. The university's Energy Frontier Research Center (NEES) pointed out that different from traditional flat-thin-film solid battery, 3D micro-batter can store more energy, plus more power, in the same space.

Lithium battery comprises anode, cathode, and electrolyte, which is the medium for lithium ions traveling between the former two, the larger the contact surface of anode /cathode and electrolyte, the faster the moving speed of ions and the shorter the time for them to reach the other electrode. Therefore, the larger the surface area the higher the energy density of batteries, a reason for many scientists have been scrambling to invent 3D batteries, which turns out to be a tall order, as evidenced by failure of scientists to break through the bottleneck and commercialize the technology over the past 10 years.  

Photo courtesy of《ACS NANO》

To break the bottleneck, NEES researchers drilled deep holes as small as spider silk on silica sheets and then heated electrodes, solid electrolyte, and current collector via atomic-layer deposition before plating them, in the form of single atomic membrane, on substrate surface and inside holes one layer after another.

Such a method can assure coverage of every hole on a silica sheet, expanding the surface area of batteries, while thin battery layers can boost power density. Keith Gregorczyk, assistant research scientist at NEES, noted that the research shows that energy and power density would increase along with expansion of surface area.

Another major merit of the battery is its solid electrolyte, different from traditional lithium battery which contains flammable liquid electrolyte. Gary Rubloff, major researcher, pointed out that similar to IC chips, the technology's process can be incorporated into various equipment directly, including health sensors and mobile phones.

Although lithium battery has emerged as the mainstream energy storage technology, boasting extensive applications, such as mobile phones, 3C products, electric cars, or large-scale energy-storage facilities, safety of its electrolyte has been a lingering concern. The new energy will contribute to the solution of the problem, facilitating the production of safe and lightweight batteries. Result of the research has been published on "ACS NANO."

References:

• A New Dimension for Batteries
• Three-Dimensional Solid-State Lithium-Ion Batteries Fabricated by Conformal Vapor-Phase Chemistry

(First photo courtesy of Pixabay, written by Daisy Chuang)