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Rechargeable Proton Battery Demonstrated

Researchers have demonstrated for the first time a working rechargeable “proton battery” that could reconfigure how we power our homes, vehicles and devices. The battery is environmentally friendly and could store more energy than current lithium-ion batteries.

Potential applications for the proton battery include household storage of electricity from solar photovoltaic panels, just like Tesla’s lithium-ion Powerwall battery. With some modifications and scaling up, proton battery technology may also be used for medium-scale storage on electricity grids like South Australia’s new giant lithium battery, as well as to power electric vehicles.

The prototype proton battery uses a carbon electrode as a hydrogen store, coupled with a reversible fuel cell. During charging, protons produced by water splitting in the reversible fuel cell are conducted through the cell membrane and directly bond with the storage material with the aid of electrons supplied by the applied voltage, without forming hydrogen gas.

This process is reversed to produce electricity: hydrogen atoms are released from the storage and lose an electron to become protons once again. These protons then pass back through the cell membrane, where they combine with oxygen and electrons from the external circuit to re-form water.

A potential advantage of the proton battery is much higher energy efficiency than conventional hydrogen systems, making it comparable to lithium-ion batteries. The losses associated with hydrogen gas evolution and splitting back into protons are eliminated.

“As the world moves towards inherently-variable renewable energy to reduce greenhouse emissions and tackle climate change, requirements for electrical energy storage will be gargantuan, says lead researcher Prof John Andrews of RMIT University. “Powering batteries with protons has the potential to be more economical than using lithium ions, which are made from scare resources. 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.”

The researchers’ experiments showed that their small proton battery, with an active inside surface area of only 5.5 cm2 (smaller than a 20¢ coin), was able to store as much energy per unit mass as commercially-available lithium-ion batteries before the battery had even been optimised. “Future work will now focus on further improving performance and energy density through the use of atomically-thin layered carbon-based materials such as graphene, with the target of a proton battery that is truly competitive with lithium-ion batteries firmly in sight,” Andrews said.

The research has been partly funded by the Australian Defence Science and Technology Group and the US Office of Naval Research Global, and has been reported in the International Journal of Hydrogen Energy (https://goo.gl/6i5kJk).