The rapid development of flexible and wearable devices has given manufacturers and consumers higher and higher requirements for highly efficient flexible batteries. However, the flexible lithium-ion battery is not an emerging concept, but its development is still under study stage. Recently, Columbia University based on the concept of the human spine, developed a flexible lithium-ion battery, and the battery storage efficiency, energy density and flexibility than in previous batteries even higher.
The cell is made of a lithium cobalt oxide cathode, a graphite anode, and copper and aluminum collectors and a polyethylene support membrane. The internal material is similar to the spine discs and ligaments, whether it is elongated or twists and turns can have a stable voltage, so the battery can be used for wearable technology, flexible devices and displays.
At present, major manufacturers have similar technologies, such as Japan’s Panasonic, South Korea KAIST and LG also have R & D-related lithium-ion battery. Yuan Yang, an assistant professor who leads the team, said the battery’s energy density is currently the highest at 242 Wh / L, about 86.1% of the standard battery.
The battery prototype is designed using the spine model, the thick and hard electrode wound on flexible parts and to store energy, the concept is somewhat similar to the spinal cord wound on the bone marrow above, and this design allows the battery has a better Flexibility. Yang said that as the battery is a bionic design, it has passed the rigorous mechanical load test. Now the research team is optimizing the design and improving performance, hoping to become the first generation of flexible commercial lithium-ion battery.
The team cut the traditional anode, cathode, and separator into strips that resemble multiple branches that extend from the backbone and then wind them around the backbone to create a stack with energy-storing effects. This integrated battery design allows energy density to easily reach 90%.
The team said that the battery can still be cycled to charge and discharge even in a flexed condition, and that the discharge capacity of the battery can be kept at 94% after 100 repeated charge and discharge cycles. Yang pointed out that even after a thousand times the distortion and reverse, the battery performance will not decay. Flexible batteries can be used on smartphones and tablets, and even smart clothes and smart glass, but the research team also pointed out that the complexity of technology and applications increases costs.