Researchers at the University of Maryland (UMD) Energy Research Center and A. James Clark School of Engineering are developing solid-state battery technology, and report they have made an advance by inserting a layer of ultra-thin aluminum oxide between lithium electrodes and a solid non-flammable ceramic electrolyte known as garnet. They say this development will help in the effort to produce batteries that are safe, powerful and affordable.

Prior to this advance, the researchers say 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, decreasing the battery's ability to charge and discharge.

The team solved the problem of high impedance with the layer of aluminum oxide, which decreases the impedance 300 fold, they say. This virtually eliminates the barrier to electricity flow within the battery, allowing for efficient charging and discharging of the stored energy.

A paper describing the research was published online in the journal Nature Materials.

They say that 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 solid-state electrolyte.

In addition, the high stability of these garnet electrolytes enables the team to use metallic lithium anodes, which contain the greatest possible theoretical energy density. Combined with high-capacity sulfur cathodes, this all solid-state battery technology offers an energy density that could outperform any lithium-ion battery currently on the market, the research team says.

Researchers say that 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 the size, weight, and cost of batteries.