The smartphone industry in particular and the consumer electronics segment in general is ceaselessly innovating everyday. There has been much talk lately about flexible smartphones, displays and batteries. To make a smartphone that is wholly and truly flexible, the heart of it that powers it should definitely be a flexible and reliable unit. Flexible batteries are being envisioned, designed and improvised upon as we speak.
Though the idea of a thin-film battery has been around for a while as a nebulous concept, the project has started getting into a concrete shape with the work carried out by researchers at the Korea Advance Institute of Science and Technology (KAIST). They have brought out a very promising solid state, thin-film Lithium-ion battery that claims the highest energy density ever achieved for a flexible battery.
How do they work?
Conventional Li-Ion batteries depend on a liquid electrolyte as the medium through which Lithium ions swim from one electrode to the other. This battery though, has an issue that the film separating the electrolytes may melt under heat, in which case the positive and negative terminals may come into contact causing an explosion. This may be the explanation for all those smartphones that go up in flames. In contrast, in a thin film battery, one polymer, typically polyvinylidene fluoride, functions as a glue that binds tiny conductive carbon particles to those of the metal oxide and graphite that normally compose the battery’s cathode and anode respectively. The other polymer, often polyethylene or polypropylene, serves as a barrier between the electrodes. It physically separates the battery’s positive and negative terminals to prevent the battery from short-circuiting but allows Lithium ions to shuttle back and forth between the electrodes as the battery is discharged to provide power and then recharged.
By the judicious choice of polymers and replacement of some battery components, researchers and a handful of manufacturers are now designing batteries with atypical properties such as mechanical flexibility, thus creating the so-called flexible batteries.
Advantages of flexible batteries:
Highly flexible batteries would free product designers from the constraints of rigid and predetermined forms. A smartphone might fold up in your pocket. Electronically controlled drug delivery patches could stretch around your arm. Products could take on the form best suited to the application, not the form dictated by a bulky power source. These flexible batteries also solve the problem of safety posed by the conventional Lithium-ion batteries.
One severe limitation though of the flexible batteries is the internal short circuiting that occurs during flexing. A lot of work has already gone into dealing with this and a few other problems with companies gearing up to release bendable smartphones into the market soon. Samsung with it’s YOUM OLED display and LG Display with it’s OLED panels are top contenders.