An All-Solid-State Carbon-Air Battery Reaching an Output Power over 10 W and a Specific Energy of 3600 Wh kg-1

Abstract Carbon-air batteries have a very high theoretical specific energy. However, they have not been given sufficient attention because of the challenges associated with optimizing the battery design and making it rechargeable. Here we report a novel carbon-air battery stack based on solid oxide electrolyte which enables high operating temperature. The battery is composed of a tubular membrane electrode assembly (MEA), with a solid oxide electrolyte layer sandwiched between two porous electrodes, and carbon powder filled inside the MEA tube. By introducing a row of holes along the length direction of the MEA tube for current collection, the performance of the battery can be significantly enhanced because of shortened current paths. By using a removable quartz plug to stuff the open end of the MEA tube, the battery becomes mechanically rechargeable. Several batteries can be assembled into a stack by connecting the batteries in electrical series through the holes for current collection. A 3-battery-stack operating at 800 °C displays an output power of 11.0 W, corresponding to ∼160 mW cm-2. With an overall carbon powder of ∼10 g, the stack discharges at 0.5 A and ∼2.75 V for 26 h, revealing a specific energy of ∼3600 Wh kg-1, which is significantly higher than those of the state-of-the-art metal-air batteries.