Austrian researchers have created a laboratory-scale, solid-state oxygen-ion battery based on mixed ionic electronic conduction (MIEC), a special class of non-flammable electroceramic materials. The energy density of the battery is about 30% of the energy density of lithium-ion batteries, but it is claimed to achieve a longer service life.
Scientists aim to show that MIEC perovskite-type oxides, electroceramic materials commonly used in solid oxide fuel and electrolysis cells, can be used to make a solid-state oxygen-ion battery that operates at 350-500C. .
“These oxygen-ion batteries may offer certain advantages over other battery technologies such as (lithium-ion), sodium-sulfur or ZEBRA batteries,” the researchers said. “Consisting only of solid, non-flammable oxides, they pose much less of a safety risk in the event of a device failure. In addition, they can be made from mostly abundant elements, and in particular are not dependent on critical elements such as cobalt or lithium.
The team used a ceramic material called yttria stabilized zirconia (YSZ) and MIEC thin-film electrodes as model cells. These ceramic materials can absorb and release doubly negatively charged oxygen ions. With an electric voltage, the oxygen ions move from one ceramic material to another, after which they can be made to travel back, creating an electric current.
“This is very similar to lithium-ion battery electrodes, which store electrical energy by changing their lithium content. Essentially, voltage-controlled oxygen stoichiometric changes correspond to the charging/discharging of chemical capacitance, thereby preventing self-discharge via atmospheric oxygen exchange,” the researchers explained.
Crucially, they believe that exchanging oxygen with the atmosphere in the other direction can lead to very long battery life.
“The oxygen-ion battery can be regenerated without problems: If oxygen is lost due to side reactions, the loss can simply be compensated with oxygen from the surrounding air,” said TU Wien.
The academics made full cells of solid-state oxide batteries by connecting two electrodes with different oxygen addition potentials and used them to predict the performance of an optimized solid-state oxide-ion battery.
The results show volume energy densities up to 140 mW h cm-3, which corresponds to about 30 percent of the volumetric energy density of current lithium-ion batteries, according to the researchers. DC measurements of the cell showed a capacity of up to 120 mA h cm-3 with a cell voltage of 0.6 V at 350 – 400 C. Both electrodes showed cyclic performance with Faraday efficiencies above 99%.
“If you need a large energy storage unit for temporary storage of, for example, solar or wind energy, an oxygen-ion battery can be an excellent solution,” researcher Alexander Schmid said. “If you build an entire building full of energy storage modules, lower energy density and higher operating temperature are not decisive. But the strengths of our battery would be particularly important there: long life, the possibility to manufacture large quantities of these materials without rare elements, and the fact that these batteries do not have a fire hazard.
The authors shared their findings in “Rechargeable Oxide-Ion Batteries Based on Mixed Conducting Oxide Electrodes,” published recently Advanced energy materials. They have filed a patent application for their invention.
