A pilot study in Japan has proven the possibility of rechargeable air batteries as an energy source. With further advancement and refinement, such batteries may be able to overcome the problems attached to existing metal batteries and become a mainstay.
In our highly technologically dependent society, batteries can be considered a necessity. Name a piece of technology, and its functioning will most likely be the result of batteries. Batteries are compact sources of energy that work as a mediator between an electric supply and an electronic device. There are two types of batteries: primary and secondary batteries. Primary batteries are non-rechargeable and are used in appliances such as torches or remote controls. Meanwhile, secondary batteries are most commonly found in items that are rechargeable, such as mobile phones. Regardless, they work the same way. Essentially, batteries are made up of three components: a cathode (positive terminal), an anode (negative terminal), and an electrolyte that connects them together. In existing batteries, the cathode and anode are usually metals, while the electrolyte is a liquid.
Electricity in batteries is generated by chemical reactions that occur within them, hence the term electrochemical energy. The anode reacts with electrolytes, producing electrons. Simultaneously, the reaction between the cathode and the electrolyte allows the cathode to accept these released electrons. This transfer of electrons can then be harvested for electrical power.
Commercially available secondary batteries are problematic due to their negative environmental impacts and reduced efficiency over multiple uses. This lowered efficiency is usually attributed to the formation of dendrites, or projections of metal, that can build up and shorten battery life. Hence, there has been a great demand for batteries with high capacity, durability, environmental compatibility, and low cost.
One of the efforts that have been made to overcome the problems associated with metal batteries is the development of a rechargeable air battery. However, scientists in the field have been faced with numerous stumbling blocks. Firstly, developed hybrid metal-air batteries are unstable and usually accompanied by issues of high resistance, leaching, or combustion. To overcome this problem, scientists tried replacing metal with organic molecules. Although the results were promising, these batteries still use liquid electrolytes, which come with safety concerns.
With this, researchers from Japan have taken the challenge of constructing an all-solid-state rechargeable air battery (SSAB) that comprises organic molecules as electrodes and a proton-conducive polymer (Nafion) as the electrolyte. The team, led by Professor Kenji Miyatake from Waseda University and the University of Yamanashi, published their novel invention in Angewandte Chemie International Edition.
To evaluate the efficiency of SSAB, the authors investigated its charge/discharge performance, rate characteristics, and cyclability. Although the SSAB was functional, they found that SSAB’s performance was nowhere near as good as that of existing batteries or even metal-air batteries. For instance, the charge/discharge cyclability of the SSAB was not very satisfactory, with a discharge capacity of only 44% remaining after 30 cycles. On the plus side, unlike batteries that use metals as electrodes, SSAB did not deteriorate in the presence of water and oxygen.
As a pilot study, the authors were able to prove the concept of SSAB experimentally. Hence, although its performance is still primitive, SSAB holds promise as the next generation battery technology. To illustrate, minor tweaking of the materials by the researchers resulted in a significant improvement in the capacity of SSAB. Hence, with the goal of improving their device and making it commercially available, the authors will continue to experiment with the materials they use to improve the stability and effectiveness of SSAB.
Overall, SSAB could be the replacement for the problematic metal batteries that currently exist on the market. Given their potential, further advancement in SSAB is certain. Such technology will have the power to extend the battery life of small electronic gadgets, especially smartphones, while remaining in line with the worldwide goal of becoming a carbon-free society. [APBN]
Source: Yonenaga et al. (2023). All‐Solid‐State Rechargeable Air Batteries Using Dihydroxybenzoquinone and Its Polymer as the Negative Electrode. Angewandte Chemie International Edition, e202304366. https://doi.org/10.1002/anie.202304366