The cotton-based microfluidic Al-air batteries automatically deliver the electrolyte by the capillary force, available as the power supply for microelectronic devices. However, among these Al-air batteries, only one side of the Al anode participates in anodic reactions, wasting the anode and decreasing the anodic utility. To address the issues and gain a compact battery, the cotton-based Al-air battery with the double-side reactive anode is presented. It is comprised of the two air-breathing cathodes, two cotton channels and one anode. This battery shows a high specific capacity of 2856 mA h g−1 at 10 mA cm−2 current density, corresponding to the anodic utility of 95.8 %. At 3.5 mg cm−2 catalyst loading and 4 mol L−1 NaOH, the battery performance is optimal, with the peak power density of 28.0 ± 0.1 mW cm−2 and the limiting current density of 81.0 ± 4.1 mA cm−2. To further simplify the battery, the electrolyte container and absorbent pad are removed, and the electrolyte is non-flowing. The peak power densities of the batteries with or without the flowing electrolytes are almost the same. Finally, the stacks connected from the two batteries in series with and without the flowing electrolytes can light 63 and 50 light-emitting diodes.