A Strain-Anchoring Iodine Strategy Enables High-Performance Zinc-Iodine Microbatteries for Semi-Bionic Micro-Robots

Next-generation intelligent miniaturized systems, such as biohybrid robots, depend on lightweight and high-energy-density micro-power sources. Zinc-iodine microbatteries (ZIMBs) with high theoretical capacity and intrinsic safety are promising, yet still suffer from sluggish iodine redox kinetics and severe polyiodide shuttling under micro-electrode spatial constraints. Here, we present a strain-engineered carbon nanotube/polyvinyl alcohol hydrogel framework. The induced strain modulates the electronic structure of carbon nanotubes, activates additional iodine-anchoring sites, and lowers the Gibbs free energy of iodine redox, thereby enhancing polyiodide interfacial interaction and conversion kinetics. The resulting ZIMB delivers an ultrahigh areal capacity of 4273 µAh cm⁻² and areal energy density of 2 mW cm⁻², outperforming the best-reported zinc-based microbatteries by 2.2 times. Moreover, two serially connected ZIMBs provide 2.5 V and 1.5 mA while weighing only 56 mg, which is merely one-tenth the weight of a commercial CR1220 battery under similar discharge conditions. This system meets the stringent sub-70 mg power-source requirement for biohybrid micro-robots and successfully powers a Bluetooth-controlled microelectronic backpack, enabling real-time behavioral modulation of flying bumblebees. This work achieves a combination of high output and minimal mass that remains beyond the reach of existing solutions, advancing the development of high-performance semi-bionic micro-robots.