The big problem with nowadays’ batteries is that they charge and discharge slowly. They can be made to charge and discharge faster at the price of their shortened lifetime, but that’s not a solution at all. Supercapacitors may offer fast charge/discharge rates, but their capacity is just not very high. A hybrid of these two would be perfect.
Paul Braun, from the University of Illinois, has developed a three-dimensional cathode that may just be the solution for fast-charging batteries. “This system that we have gives you capacitor-like power with battery-like energy,” said Braun, a professor of materials science and engineering. “Most capacitors store very little energy. They can release it very fast, but they can’t hold much. Most batteries store a reasonably large amount of energy, but they can’t provide or receive energy rapidly. This does both.”
Unlike lithium-ion or nickel metal hydride batteries, whose capacity lowers as they are used in high loads, Braun’s batteries do not manifest that way. He created a thin porous film that allows any battery technology to use it and that has both a high capacity and allows for large currents to get in or out of it.
The battery electrodes that Braun has invented make it possible for a laptop to be charged in as little as a few minutes or phones that could charge in seconds, let alone electric cars, that could juice themselves in the same time you’d need to fill the gas tank.
The secret for Braun’s electrodes is coating a surface with tiny spheres packed tightly together to form a lattice. This method has been proved to be both efficient and cheap, since they place themselves automatically. Then, the space between the spheres is filled with metal, they then melt (or dissolve) the spheres, and get a porous three-dimensional porous metal scaffold. Through a process called electropolishing the surface of the scaffold is uniformly etched and the pored enlarged.
The obtained porous scaffold is then coated with a thin film of the active electrode material, which allows a fast electron diffusion. The small interconnects formed between the active material which fills the “bubbles” in the frame ensures that the lithium ions can move quickly through the structure.
Braun says this technology can be adapted to any kind of battery “This is not linked to one very specific kind of battery, but rather it’s a new paradigm in thinking about a battery in three dimensions for enhancing properties.”
If this work is properly funded and developed, in a few years we’ll have 5 minutes-charging cars, ultra-quick laptop chargers and mobile phone independence we don’t even realize could be possible today.