Electroplating delivers high energy batteries
Image: Electron micrograph cross-section of aluminum foil plated with lithium cobalt oxide, a common material in lithium-ion batteries. [Hailong Ning and Jerome Davis III, Xerion Advanced Battery]
Researchers at the US-based University of Illinois, Xerion Advanced Battery and Nanjing University, China, have developed a method for electroplating lithium-ion battery cathodes.
The technique delivers high-quality, high-performance battery materials, opening the door to flexible and solid-state batteries.
"This is an entirely new approach to manufacturing battery cathodes, which resulted in batteries with previously unobtainable forms and functionalities," highlights Professor Paul Braun, Director of the Frederick Seitz Materials Research Lab at Illinois.
Traditional lithium-ion battery cathodes use powders mixed with glue-like binders to form a slurry that is spread on a thin sheet of aluminum foil and dried.
But as Braun's colleague, Hailong Ning, Director of Research and Development at Xerion Advanced Battery, points out: "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."
"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," he adds.
Given this, the researchers have developed a general low-temperature (260°C) molten salt electrodeposition method to directly electroplate the Li-ion battery cathode materials onto aluminium foil.
During electroplating, a pulsed waveform is applied between the working and the reference electrodes; the researchers discovered that pulsed deposition forms higher-quality material on the planar electrodes than constant current or voltage deposition.
What's more, pulsed deposition also allows the researchers to infill the 3D structured electrodes.
Illinois Professor Paul Braun and Hailong Ning, Director of Research and Development at Xerion Advanced Battery have led a research team that has developed a method for directly electroplating lithium-ion battery cathodes. [L. Brian Stauffer]
Thanks to the lack of glue, an electroplated cathode packs in 30 percent more energy than a conventional cathode, claim the researchers.
The cathode can also charge and discharge faster, as the current passes directly through the electrode, without having to traverse the inactive glue or slurry's porous structure.
The researchers have demonstrated the technique on carbon foam as well as foils and surfaces with different textures, shapes and flexibility, opening the door to .
"This method opens the door to flexible and three-dimensional battery cathodes, since electroplating involves dipping the substrate in a liquid bath to coat it," says Professor Huigang Zhang from Nanjing University.
"These designs are impossible to achieve by conventional processes," adds Braun. "But what's really important is that it's a high-performance material and that it's 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," he concludes.
Research is published in Science Advances.