With demand for energy storage solutions expected to go nowhere but up in the coming years, improving the performance of batteries, and reducing the environmental of their manufacture, are important areas of research.
Lithium-ion batteries are expected to remain the mainstream solution for energy storage for the foreseeable future, and much of the research in the field is focused on alternative materials and chemistries for these and other metal-ion batteries. But there are plenty of alternative battery types, and proton batteries represent one of the newer, less explored paths to a better performing battery.
The first working proton battery was demonstrated by scientists at Australia’s Royal Melbourne Institute of Technology in 2018. The concept is essentially a reversible hydrogen fuel cell: During charging, protons produced by water splitting are conducted through a cell membrane and into a storage material. And in discharging, the process is reversed to reform water.
Scientists at Uppsala University in Sweden chose to work on the proton battery concept thanks to the potential to design batteries that don’t rely on rare, expensive or otherwise problematic materials. “A great many of the batteries manufactured today have a major environmental impact, not least due to the mining of the metals used in them,” explained Uppsala University’s Christian Strietzel. “The point of departure for our research has therefore been to develop a battery built from elements commonly found in nature and that can be used to create organic battery materials.”
The proton battery developed by the Uppsala team is described in An all-organic proton battery energized for sustainable energy storage, published in Angewandte Chemie. The group worked with two organic molecule groups – quinones and thiophenes – as electrode materials, with an acidic aqueous solution as the electrolyte.
The battery can be charged at a constant voltage, and reached its full capacity of 60 milliamp-hours per gram within 100 seconds, which the group says would make it ideal for integration with a PV installation. After 500 cycles, the battery retained 85% of its initial performance, and was shown to retain these favorable characteristics at temperatures down to -24 C.