Cornell University engineers have developed a new structure for a typical household battery. From the classical scheme, with the spaced cathode and anode, they moved on to the most complex three-dimensional architecture, where the electrodes have an ultra-thin shape and are constantly intertwined with each other. But they do not overlap - this is how a colossal increase in power density and battery charging speed is achieved while maintaining the same dimensions.
The internal structure of a 3D battery is described by the term "gyroid" - a continuous, infinitely twisting structure in three dimensions, but at the same time it does not intersect itself anywhere. It is made of a carbon film with a thickness of several nanometers, which is close to graphene, but at the same time it is not. A 10-nm dielectric layer is deposited on the carbon anode, on top of which a sulfur cathode film is located. And all of this is embedded in PEDOT electrically conductive polymer.
The intricacies of the gyroid form a huge number of microcells with a diameter of about 40 nm, each of which can be considered as a tiny battery. They are all very tightly packed to minimize voids inside the battery, resulting in less time and energy lost in the passage of electrons during charging / discharging. The power density of the battery grows, and the charging speed drops to a matter of seconds or even fractions of a second.
The disadvantage of a 3D battery is irreversible wear, since when the sulfur cathode expands, small fragments break off from it due to the pressure on the polymer layer. Over time, this will lead to loss of contact and some areas inside the battery will become isolated. This can be called battery degradation and the research team is currently working on a solution.