Stretchable High-Power Batteries For Soft Robotics And Wearable Electronics

Stretchable batteries using sliding electrodes with high mechanical flexibility, capacity, and power performance.
Problem:
Soft robotics and stretchable electronics have widespread applications in medical devices, health monitoring, and human-machine interfaces. These devices require batteries to ensure portability, but they can often add bulk and rigidity. Current technologies employ component-level stretchability, where both electrodes and electrolytes are compliant. Developing these technologies require complex processing techniques, where component-level flexibility results in a trade-off between battery performance and stretchability. Thus, there is a need for durable, high performance stretchable batteries.
Solution:
The flexible metal-air batteries employ a sliding interface between the rigid electrodes and a highly stretchable hydrogel electrolyte. The hydrogel electrolyte conducts ion transfer between the electrodes and elongates in response to forces applied to the battery, while the electrodes retain their original shapes and slide freely on the interface. The batteries can withstand a variety of mechanical deformations while maintaining compliance and a high-power output.
Technology:
Stretchable batteries contain a sliding interface between rigid electrodes and a stretchable polymer hydrogel electrolyte. The electrodes retain their original shapes and slide between the electrolyte and the elastomeric enclosure, while the electrolyte facilitates ion transfer between the electrodes and can elongate in response to mechanical deformation. This system directly utilizes rigid commercial electrodes without additional processing. Consistent contact at the electrode-electrolyte interface optimizes the stretchable battery capacity and performance. The battery has been assessed to withstand stretching, twisting, and bending forces while consistently powering soft robot motors or sensor circuits.
Advantages:

Stretchable batteries have an energy density peak of 104 mWh cm−2, outperforming most flexible metal-air batteries
All the materials on stretchable battery electrodes contribute to the electrochemical reactions, maximizing the battery’s capacity and reducing cost
Stretchable batteries demonstrate mechanical compliance by withstanding physical deformations in soft robots
Stretchable batteries seamlessly integrate with soft robots’ onboard sensors and preserve their inherent compliance
Stretchable batteries have wide-ranging applications including wearable devices, medical devices, and other stretchable electronics

Stage of Development:

Bench Prototype

(A) Computer-Aided Design (CAD) schematic of the stretchable battery encased in an elastomeric enclosure. Rigid electrodes interact with a stretchable hydrogel electrolyte through a sliding interface. (B) Mechanical characterization of the stretchable battery. Sequential images demonstrate the stretchable battery powering three soft robotic motors at various stages: undeformed, at strain 𝜀 = 0.51, a bending angle = 180°, a twist angle of = 180°, and post-impact from a hammer over a period of 28 seconds (s).
Intellectual Property: