I’ve posted quite a few times now, about Lithium-Ion Batteries, without ever answering the question of how Lithium-Ion Polymer Batteries differ. And I think that I should write a posting about that subject, which this time around, will contain no links to other articles.
My previous postings assumed that standard, lithium-ion batteries are being examined, which were not of the polymer variety, but those postings did mention plenty of possible electrode materials. Well, batteries are not solely defined by their electrode materials, but are sometimes defined as much, by the choice of electrolyte which Engineers put their trust in.
In a standard, lithium-ion battery, most of the time, the electrolyte needs to be kept under pressure, in order to be liquid. In fact, this means that the standard battery variety also has a pressurized container around it, from which its electrodes are insulated electrically, but that adds bulk. The electrolytes in question are not Brønsted acids, as was once the case with lead – lead oxide batteries, but are very flammable.
In a polymer-variety battery, the electrolyte is the polymer, but the same assortment of electrode materials is still available. The favorite composition for the positive electrode seems to be lithium-iron-phosphate. Because the electrolyte is the polymer, it counts as a solid, which does not need to be kept under pressure, and through which lithium ions effuse, even though this solid is also flexible. As soon as this option presents itself, it creates advantages on two fronts:
- Energy-to-mass ratio,
(Updated 10/25/2018, 13h25 : )