The cell exhibited excellent thermal stability and rechargeability in the 30–105 °C temperature range. It was subjected to 40 charge–discharge cycles at current densities ranging from 0.05 to 0.25 mA/cm².

Lithium-air batteries dispense with the intercalation cathode used in a lithium-ion rechargeable battery, instead using a catalytic air cathode in combination with an electrolyte and a lithium anode. Oxygen from the air is the active material for the cathode and is reduced at the cathode surface—the lithium reacts directly with the oxygen. Theoretically, with oxygen as essentially an unlimited cathode reactant source, the capacity of the battery is limited only by the lithium anode. The theoretical specific energy of the Li-air cell is 13,000 Wh/kg—the highest of any metal-air battery system. (Earlier post.)

There are numerous challenges for non-aqueous rechargeable Li-air systems, such as low rates of oxygen diffusion in the porous air cathode and the accumulation of solid reaction products on the electrode, which blocks the contact between electrolyte and air, reducing life and power. As with Li-ion batteries, there are many factors controlling the performance of a lithium-air battery, including cathode structure, anode morphology, electrolyte composition and cell assembly.

We have successfully fabricated and tested the first totally solid-state lithium-air battery, which represents a major advancement in the quest for a commercially viable, safe rechargeable battery with high energy and power densities and long cycle life.

—Binod Kumar, leader of UDRI’s electrochemical power group

In addition to increasing the battery’s energy density, the development is designed to mitigate the volatile nature of traditional lithium rechargeables, such as those used in cell phones and laptops, which can overheat and catch fire or rupture.

Kumar said that the team made and tested more than three dozen lithium-air batteries during the last year, with each exhibiting superior performance even at temperatures as high as 107 °C. As development of the technology continues, researchers will also focus on cycle life, with a goal of 4,000 cycles.

Research to develop the new lithium battery was funded in part by the Air Force Research Laboratory’s Propulsion Directorate at Wright-Patterson Air Force Base.

Resources

• Binod Kumar, Jitendra Kumar, Robert Leese, Joseph P. Fellner, Stanley J. Rodrigues, and K. M. Abraham (2010) A Solid-State, Rechargeable, Long Cycle Life Lithium–Air Battery. J. Electrochem. Soc., Volume 157, Issue 1, pp. A50-A54; doi: 10.1149/1.3256129