While the Li-ion battery is initially built from a conventional anode/separator/cathode/ separator stack, the spine-inspired design involves cutting strips that extends from a common backbone, then wrapping those strips around their connecting backbone, forming thicker stacks flexibly connected to one another.
The result described in a paper titled "Bioinspired, Spine-Like, Flexible, Rechargeable Lithium-Ion Batteries with High Energy Density" published in the Advanced Materials journal shares some similarities with a spinal column. The thick stacks (with a high energy density) are akin to the vertebra in the spine, while the thin unwound backbone connecting all the stacks could be compared with the soft marrow of the spinal cord, the whole assembly remaining flexible.
In their paper, the researchers describe a LiCoO2/graphite flexible cell, which, although non-optimized, boasted an energy density of 242Wh L−1 including the package, nearly on par (over 86%) with that of conventional prismatic cells, but with the added flexibility. Under various mechanical tests (flexing and twisting at 90º), the fabricated samples exhibited stable charge/discharge cycles, even under continuous dynamic load.