In sewing, strings of various thickness and stiffness are used for piping, a type of trim inserted into a seam to define the edges or style lines of a garment or bag.
A team of researcher at LG Chem seems to add another function to the piping: they developed a Li-Ion battery in string form just a few millimeter thick, is bendable and can even be knotted without compromising it’s battery function.
The energy storage technology is based on Li-Ion chemistry just like conventional Li-Po batteries only twisted into a round, fine string instead in a flat, geometrical form factor.
Thin strands of nickel and tin coated copper wires form the anode. The researcher then spin the coated copper wires into metal yarn, wrap it around a rod to form a spring shape which functions as structural element of the string battery as well as the anode.
The cathode is formed from a lithium cobalt oxide coated aluminum wire wrapped around the anode yarn. Liquid electrolyte is poured down the middle of the spiral shaped wires to activate the chemical reaction. The electrodes are covered and sealed off with a protective insulation layer on the outside.
All this sounds very interesting and I can already imagine the many usage areas in the wearable technology field. The battery capacity will most likely depend on the length and diameter of the string, giving quite some creative room for a reasonable, sizable power supply completely integrated in garments and bags.
When will we get string cable batteries? In about 5 years according to Je Young Kim, general manager of battery R&D at LG Chem.