Stretchable Metal‐Air Batteries Through Sliding Electrodes

Soft robots and wearable technologies benefit significantly from stretchable batteries, yet the rigid nature of high‐capacity electrodes creates large trade‐offs in battery performance and stretchability. This study introduces a new approach for realizing stretchable batteries by allowing the electrodes to slide along a stretchable electrolyte. When the sliding‐electrodes battery is stretched, the forces are transmitted through the hydrogel electrolyte and elastomeric enclosure, while the rigid electrodes slide relative to the hydrogel to maintain interfacial contact. The sliding‐electrodes approach allows 100% of the unstretched battery area to be covered by thick electrodes so that the battery areal capacity and power are improved by up to 10X of prior stretchable designs. Three metal‐air batteries achieve areal capacities of up to 104 mWh cm−2. Further mechanical testing, electrochemical characterization, and integration into soft robotic systems demonstrate the potential of these stretchable batteries in practical applications. The sliding‐electrodes battery can stably power multiple servo motors and sensing circuits under stretching, twisting, bending, and after impact. This research introduces a method for realizing stretchable batteries whereby the electrodes slide along a stretchable electrolyte. The design allows thick and rigid electrodes to cover the entire area of the unstretched battery which enhances areal capacity and power. The stretchable metal‐air batteries power soft robots and actuators while being stretched, twisted, and hammered.