Cell scaffold blood-brain-barrier. (Credit: A. Marino/ Smart Bio-Interfaces, IIT Pontedera)

A team of engineers has developed a prototype Li-ion battery that obtains both good flexibility and high-energy density. It allows remarkable flexibility, high energy density, and stable voltage no matter how it is flexed or twisted.

The team cut the conventional anode/separator/cathode/separator stacks into long strips with multiple “branches” extending out 90 degrees from the “back-bone.” The team then wrapped each branch around the backbone to form thick stacks for storing energy, like vertebrae in a spine. With this integrated design, the battery’s energy density is limited only by the longitudinal percentage of vertebra-like stacks compared with the whole length of the device, which can easily reach over 90 percent.

The battery shows stable capacity upon cycling, as well as a stable voltage profile no matter how it is flexed or twisted. After cycling, the team found that the positive electrode was intact with no obvious cracking or peeling from the aluminum foil, confirming the mechanical stability of their design.

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