We've covered our fair share of flexible electronics, but as far as bendability goes, the flexible batteries developed by LG are truly raising the bar by a couple of notches. The Korean company is working on a battery that is shaped like a cable, and can be bent, tied, or even woven into fine sheets with almost no loss in discharge performance.

It's no secret that the form-factor of today's portable electronics is severely constrained by the shape of its batteries. Nowadays, manufacturers use the thinness of their devices as the main meter of their technical prowess. Removing the rigidity limitation, along with improvements in flexible display technology, could open entirely new markets and lead to a paradigm shift that will make device design an even more important factor than it is now.

Lately, researchers have tried to build flexible batteries using soft materials—polymer electrolytes, nanometer-sized materials, and flexible current collectors—often sacrificing capacity.

The Korean researchers are trying a completely new approach to develop a battery that is highly scalable, can be manufactured with a wide range of capacities, and is also extremely bendy—so much so that it could be adapted to fit nearly anywhere, freeing designers from the heavy burden of the rigidity constraint.

The team coated copper wires with nickel-tin, coiled them around a rod and stretched them, obtaining a hollow spiral, spring-like flexible anode. Finally, the anode was coupled with a lithium-ion cell. The elegance of this design is that the electrolyte can be easily injected in the battery and is easily spread throughout the electrodes. Also, more importantly, battery capacity can be simply designed by controlling the number of copper wires and the thickness of the cathode composite that wraps around them.

Preliminary tests showed the cable battery to be stable in discharge performance regardless of their degree of bending, with almost no change compared to a non-bending state. There was however some loss in capacity, which hasn't been characterized in detail just yet.

The batteries can be woven in series or in parallel to assume nearly any shape (including sheets) with finely controlled energy density. As such, they are versatile like no other battery. LG seems to be betting on this technology, and said that if it can resolve outstanding issues (mainly capacity loss and a more thorough investigation on safety), the batteries could soon hit the market and have an enormous impact on portable, wearable, and flexible electronics in the near future.

The study was published in the journal Wiley Advanced Materials.

Source: LG Chem

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