Getting inspiration from human spine, researchers at Columbia University in the U.S. have developed a prototype of a highly efficient, lithium-ion battery that demonstrates remarkable flexibility while providing high energy density and stable storage. The makers of the battery claim their new invention could “greatly advance the commercialization of flexible devices.”

This team of engineering researchers was led by Yang Yuan, assistant professor of materials science and engineering at Columbia University School of Engineering and Applied Science. According to the team, they got inspiration from human spine, which is mechanically robust despite being highly flexible and distortable. It is because of the soft marrow components in the spine that interconnect hard vertebra parts. Researchers used the human spine model to create a flexible, lithium battery with a similar structure.

The prototype developed by the team features thick, rigid stacks of electrodes (“vertebrae”) to store energy. These electrodes are present around a thin, flexible part (“marrow”) that connects the stacks of electrodes together, and makes the whole battery flexible. To fabricate the battery, multiple layers of electrodes are first cut into a specific shape, and then strips extending out are wound around the backbone to create a spine-like structure.

Inspired by the human spine, @CUSEAS's Yuan Yang designs a flexible lithium battery. https://t.co/xRe5PjoRtc via @inversedotcom — ColumbiaScience (@ColumbiaScience) January 31, 2018

According to Yang, the energy density demonstrated by their prototype is “one of the highest reported so far.”

“As the volume of the rigid electrode part is significantly larger than the flexible interconnection, the energy density of such a flexible battery can be greater than 85 percent of a battery in standard commercial packaging,” Yang explains.

After cycling, the battery was disassembled to find out the morphological change of electrode materials. Researchers found that the positive electrode was in perfect shape with no obvious peeling or cracking from the aluminum foil.

Continuous flexing or twisting of the battery during discharge revealed no interruption in the voltage curve. When researchers cycled the battery in the flexed state higher current densities, the capacity retention was found to be quite high (84% at 3C, the charge in 1/3 of an hour). The battery also successfully passed a harsh dynamic mechanical load test.

“Our spine-like design is much more mechanically robust than are conventional designs,” Yang says. “We anticipate that our bio-inspired, scalable method to fabricate flexible Li-ion batteries could greatly advance the commercialization of flexible devices.”

Yang says they are now optimizing the design of their battery and improving its performance.

The study was supported by startup funding from Columbia University, and the NSF MRSEC program through Columbia in the Center for Precision Assembly of Superstratic and Superatomic Solids (DMR-1420634) and sponsored by the China Scholarship Council (CSC) graduate scholarship.

The detailed findings of the study titled “Bio-inspired, spine-like flexible rechargeable lithium-ion batteries with high energy density” were published in Advanced Materials.