Scientists Design Lithium-air Batteries for Commercial Use in EVs, Drones

The demand for the development of rechargeable batteries with high energy densities has been increasing in recent years. Although lithium-air batteries represent great potential theoretically to be employed in electric vehicles, drones and other storage applications that demand high energy, they haven’t yet demonstrated the requisite efficiency and cycle performance to be commercialised for practical use. To resolve this issue, a team of researchers working at Japan’s National Institute for Materials Science has fabricated a rechargeable lithium-air battery.

To start with, li-ion batteries (LiBs), which have been used since 1991, have responded well to market needs, but the energy density of conventional LiBs does not meet the requirements of advanced energy storage devices, such as next-generation vehicles and flying objects, including drones and unmanned aerial vehicles, which slowly charge during the day and discharge overnight.

Lithium-air Batteries (LABs), on the other hand, which have the potential to achieve energy densities two to five times higher than those of LiBs, are potential candidates for next-generation rechargeable batteries for the above-mentioned application field, the scientists explain.

In the last few decades, there has been huge progress in Lithium–air batteries (LABs) technology from the view point of materials science, such as the development of a stable electrolyte against oxygen reactive species, the hierarchical porous carbon electrode, and the protective layer of lithium metal electrodes.

“Although the superior cycle performance of LABs has been widely reported in the literature in the field of academia, their commercialization has not been achieved yet. In fact, most of the current research mainly focuses on the evaluation of individual components at the material level, and only a few studies have evaluated the cell level performance of Lithium-air Batteries (LABs) under practical conditions with the appropriate technological parameters,” say the scientists.

Even for next-generation rechargeable batteries other than LAB, such large gaps between academia and industry in the research activity have been pointed out. In their mini-review article, the scientists explicate the crucial factors required for realizing LABs with high practical energy density based on the results of energy density simulations. In addition, the criteria for evaluating materials are proposed for correctly predicting their potential at the practical cell level.

In their research, the scientists delve into the key technology for realizing LABs with high energy density at the practical cell level. They state that the energy density estimation of LABs reported in the literature revealed that the cell level energy density of most of the LABs was less than 50 W h kg−1 because the cell contains an excess amount of electrolyte and/or the cell is operated at relatively small areal capacity conditions.

The researchers find that to achieve an energy density higher than 300 W h kg−1, which surpasses the level of conventional LiBs, the ratio of amount of electrolyte against the areal capacity (E/C, g A−1 h−1) should be controlled to be less than 5 g A−1 h−1.

For rechargeable battery systems equipped with a lithium metal electrode, such as lithium/NMC and lithium/sulfur, recent studies have investigated the cell level performance under practical conditions with the appropriate technological parameters . As results, the specific issues in practical cell design have been widely recognized in their research community, resulting in the close collaboration between academia and industry.

Even for the research development of LABs, advanced studies in academia should be performed under appropriate technological parameters to accurately predict the possibility of using LABs at the practical cell level, conclude the scientists.

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