The researchers are developing game-changing solid-state battery technology, and have
made a key advance by inserting a layer of ultra-thin aluminum oxide between
lithium electrodes and a solid non-flammable ceramic electrolyte known as
garnet. Prior to this advance, there had been little success in developing
high-performance, garnet-based solid-state batteries, because the high
impedance, more commonly called resistance, between the garnet electrolyte and
electrode materials limited the flow of energy or current, dramatically
decreasing the battery's ability to charge and discharge.
The University of Maryland team has solved the problem of high impedance
between the garnet electrolyte and electrode materials with the layer of
ultrathin aluminum oxide, which decreases the impedance 300 fold. This virtually
eliminates the barrier to electricity flow within the battery, allowing for
efficient charging and discharging of the stored energy.
A new paper describing the research was published online December 19 in the
peer-reviewed journal Nature Materials.
"This is a revolutionary advancement in the field of solid-state
batteries—particularly in light of recent battery fires, from Boeing 787s to
hoverboards to Samsung smartphones," said Liangbing Hu, associate professor of
materials science and engineering and one of the corresponding authors of the
paper. "Our garnet-based solid-state battery is a triple threat, solving the
typical problems that trouble existing lithium-ion
batteries: safety, performance, and cost."
Lithium-ion batteries typically contain a liquid organic electrolyte that can
catch fire, as shown by numerous consumer electronic battery fires and even the
temporary grounding of the Boeing 787 fleet for a series of battery fires. This
fire risk is eliminated by the UMD team's use of the non-flammable garnet-based
"The work by [the University of Maryland research team] effectively solves
the lithium metal-solid electrolyte interface resistance problem, which has been
a major barrier to the development of a robust solid-state battery technology,"
said Bruce Dunn, UCLA materials science and engineering professor. Dunn, a
leading expert in energy storage materials, was not involved in this
In addition, the high stability of these garnet electrolytes enable the team
to use metallic lithium anodes, which contain the greatest possible theoretical
energy density and are considered the 'holy grail' of batteries. Combined with
high-capacity sulfur cathodes, this all solid-state battery technology offers a potentially unmatched energy density that far outperforms any
lithium-ion battery currently on the market.
"This technology is on the verge of changing the landscape of energy storage.
The broad deployment of batteries is critical to increase the flexibility of how
and when energy is used, and these solid-state batteries will both increase the safety and
decrease size, weight, and cost of batteries," said Eric Wachsman, professor and
director of the University of Maryland Energy Research Center and the other
corresponding author of the paper.
"This [finding] is of considerable interest to those working to replace the
flammable liquid electrolyte of the lithium-ion rechargeable battery with a
solid electrolyte from which a lithium anode can be plated dendrite-free
when a cell is being charged," said acclaimed lithium-ion battery pioneer John
B. Goodenough, Virginia H. Cockrell Centennial Chair in Engineering at the
University of Texas, who was unaffiliated with the study.
The paper, "Negating Interfacial Impedance in Garnet-Based Solid-State
Li-Metal Batteries," Xiaogang Han, Yunhui Gong, Kun Fu, Xingfeng He, et al., was
published online December 19 in the journal Nature Materials.