A hydrogen atom deprived of an electron becomes a proton, an ion or particle with a positive charge. This is the lightest and most mobile positively charged particle in the Universe, on the basis of which it is possible to create a more capacious and powerful battery than lithium-ion. Therefore, scientists are faced with the task of developing better electrodes – anodes and cathodes – for proton batteries in order to gradually abandon the use of rare, fire-hazardous and expensive lithium.
Image source: UNSW Chemistry
Researchers from Australia, representing the Department of Chemistry at the University of New South Wales (UNSW Chemistry) and the Australian Nuclear Science and Technology Organization (ANSTO), have successfully developed and tested an organic material capable of storing protons, and used it to create a rechargeable proton battery in the laboratory.
As scientists note, in the modern world there are no anodes and cathodes with suitable characteristics for use in proton batteries. For their development, they took as a basis the compound tetrachlorobenzoquinone (TCBQ), which includes four chlorine groups. This compound consists of light molecules, but has a mediocre redox potential range. For a battery, the redox potential of the anode should be as negative as possible in order to enhance the transfer of electrons, and the cathode should be as positive as possible. Thus, pure TCBQ was not suitable and its structure had to be modified.
During the experiments, the scientists replaced four chlorine groups with four amino groups, turning TCBQ into a tetraaminobenzoquinone (TABQ) molecule. The addition of amino groups significantly improved the anode’s ability to store protons and reduced its redox potential range. Today, TABQ synthesis remains expensive, but the use of large quantities of lightweight elements will make development cost-effective in the future.
«“We have created a new low-molecular material with a large capacity for storing protons,” say the authors of the study. “Using this material, we have successfully developed an all-organic proton battery that is effective at both room temperature and sub-zero temperatures.”
The prototype proton battery withstood 3,500 cycles of full charging followed by complete discharge of the capacity. It also demonstrated high capacity and stable performance in cold conditions, making it a promising solution for renewable energy storage.
«The electrolyte in a lithium-ion battery consists of a lithium salt and a solvent that is highly flammable and causes serious concern, the authors write. “In our case, both electrodes are made of organic molecules, and there is an aqueous solution between them, which makes our battery light, safe and affordable.”
Finally, the new material solves the problem of safely transporting hydrogen. Molecular hydrogen is chemically active, whereas in the form of ions it is in a stable form. The proton-rich material can be safely transported to the desired location without fear of hydrogen leaks.