RMIT researchers have developed a proton battery, which works via a reversible process splitting water to store energy as solid-state hydrogen.
The prototype, developed by RMIT, is the first working example of a battery based on this technology and, according to the university, could ultimately be scaled up to serve similar functions to lithium-ion technology – such as EV and large-scale storage.
Key to the battery’s importance is its reliance on cheap and abundant materials – primarily carbon, when questions are already arising over the supply potential of several materials commonly used in Li-ion technology.
“The proton battery is one among many potential contributors towards meeting this enormous demand for energy storage. Powering batteries with protons has the potential to be more economical than using lithium ions, which are made from scare resources,” says lead researcher John Andrews.
“Carbon, which is the primary resource used in our proton battery, is abundant and cheap compared to both metal hydrogen-storage alloys, and the lithium needed for rechargeable lithium ion batteries,” he adds.
The prototype battery, described in the International Journal Hydrogen Energy, has an active surface area of 5.5cm² and charges by conducting protons produced by water splitting in a fuel cell through the cell membrane, where they bond directly with storage material, with the aid of applied voltage. During discharge, the process is reversed; hydrogen atoms pass back through the cell membrane to combine with oxygen and electrons to reform water.
According to RMIT, the proton battery is far more energy efficient than existing hydrogen storage technologies, and their prototype was able to store a similar amount of energy to commercially available lithium-ion batteries. In testing, the battery could store close to 1 weight-percentage (wt%) of hydrogen and discharged 0.8 wt%. The maximum cell voltage was 1.2 V.
“Future work will now focus on further improving performance and energy density through use of atomically-thin layered carbon-based materials such as graphene,” continues Andrews, “with the target of a proton battery that is truly competitive with lithium-ion batteries firmly in sight.”