“This is an entirely new approach to manufacturing battery cathodes, which results in batteries with previously unobtainable forms and functionalities,” claimed Illinois Professor Paul Braun.
The team pointed out that traditional lithium-ion battery cathodes use lithium-containing powders formed at high temperatures. The powder is mixed with gluelike binders and other additives into a slurry, which is spread on a thin sheet of aluminium foil and dried. The slurry layer needs to be thin, so the batteries are limited in how much energy they can store.
The glue also limits performance. “The glue is not active. It doesn’t contribute anything to the battery and it gets in the way of electricity flowing in the battery,” said Hailong Ning, director of R&D at Xerion. “You have all this inactive material taking up space inside the battery, while the whole world is trying to get more energy and power from the battery.”
The researchers’ solution was to electroplate lithium materials directly onto the aluminium foil. This, the team claims, provides 30% more energy than a conventional cathode, as well as charging more quickly.
“This method opens the door to flexible and 3D battery cathodes, since electroplating involves dipping the substrate in a liquid bath to coat it,” said Nanjing Professor Huigang Zhang.
The researchers demonstrated the technique on carbon foam, as wel as on foils and surfaces with different textures, shapes and flexibility. “These designs are impossible to achieve by conventional processes,” said Prof Braun. “But what’s really important is that it’s a high-performance material and nearly solid. By using a solid electrode, rather than a porous one, you can store more energy in a given volume. At the end of the day, people want batteries to store a lot of energy.”
