Untethered, dynamically deformable soft robots hold great potential for exploring extreme environments, such as space and deep sea, as well as for human-friendly technologies, including wearable electronics. A great challenge in soft robotics is the development of energy storage devices with shapes adaptable to their applications.
The research team at the Korea Institute of Machinery and Materials (KIMM) Department of Nano-Mechanics has developed a flexible, stretchable battery that bends and stretches like a snake. The ability to mimic the behavior of the creature’s individual scales could lead a snake-inspired battery to find its way into the world of soft robotics, wearable electronics, or other applications where flexibility is an important attribute.
The KIMM research team developed the highly stretchable battery with excellent stability and performance by fabricating the mechanical meta-structure mimicking a snake’s scale. Unlike conventional wearable devices, in which the device’s frame and the battery are combined in a tight formation, this new technology enables flexible movement by connecting several small, hard batteries in a scale-like structure.
To achieve this, the engineers used small, hexagonal lithium-ion battery cells resembling a snake scale that was electrically connected with polymer and copper material that used a hinge mechanism to fold and unfold. The shape of each battery cell was carefully optimized to achieve high capacity per unit size. The KIMM team has also worked to ensure battery safety by minimizing the deformation of the materials it is made of. This design also facilitates economical mass-production because the battery can be made by cutting and folding flexible electrodes with a manufacturing process inspired by the art of origami.
The team’s tests showed that the stretchable lithium battery could maintain its performance even if it was bent out of shape and stretched 90% for more than 36,000 cycles.
Thanks to these unique capabilities, the battery is suitable for applications such as search and rescue robots that need to access narrow spaces blocked off by obstacles during such disaster situations or multifunctional soft robots with artificial muscles. The snake-inspired battery cells could also prove useful in energy storage devices for those found in rehabilitation medical devices for the elderly and the sick who need physical assistance.
In the future, the team hopes to develop technology that can increase the storage capacity of soft energy storage devices.