Could dual-ion batteries be a game changer for EVs?

Electric vehicles are fast becoming popular as climate change is emerging as one of the biggest concerns in today’s world. The focus now is on how to make electric vehicles cover more ground in a single charge and generate enough power for a smooth and quick run.

Researchers are working on developing more efficient battery technologies with high-storage capacity and the least cost. On this front, one of the emerging and highly interesting research fields is the dual-ion battery (DIB). Dual-ion batteries are emerging as one of the promising technologies for sustainable energy storage and have low costs. They have potential for large-scale stationary storage of electricity. Even though the research work is in nascent stages, various combinations of electrodes and electrolytes are being used to increase the voltage output of the battery.

Dual-ion batteries are being developed by a joint project from groups in the US and Germany to push the technology further. The group is working under the leadership of Pacific Northwest National Laboratory (PNNL) in the US and the University of Münster in Germany. They fabricated a ‘zinc metal aqueous dual-ion battery’ consisting of a zinc anode, a natural graphite cathode and a concentrated bisalt aqueous electrolyte. It proved to be effective, but more work is required to optimise the whole process.

Lithium versus dual-ion batteries

No doubt, lithium-ion (Li-ion) batteries play a bigger role today for energy storage purposes. They are also already in mature stages of development. Currently, performance-wise, DIBs have only one-third capacity compared to lithium-ion batteries. Li-ion batteries also possess the highest energy densities. But they have a strong drawback: they cannot be deployed in the long term due to the scarcity of cobalt and lithium sources in the Earth’s crust. Therefore, DIBs, based on a different combination of chemistries, are generating interest due to their potential for high-efficiency energy storage and material availability as well as the excellent safety attached to them.

How do DIBs work?

DIBs are based on the working mechanism that involves the storage of cations and anions separately in the anode and cathode during the charging/discharging process. The cations and anions in dual-ion batteries are active and move in parallel from the electrolyte to anode and cathode, respectively.

DIBs can operate on a number of chemistries. Graphite is used as both electrodes and different combinations of organic salts and lithium salts are used as electrolytes. Researchers are actively experimenting with different combinations of electrolytes and electrodes to develop a battery free of lithium and other chemical elements.

Research on DIBs

Research on DIBs is still in its nascent stage. The main objective of the research is to develop a stationary storage facility that is low cost and does not involve metals like lithium, nickel and cobalt. Reasons for this are easy to understand — all these resources are becoming increasingly hard to get. So, a battery with graphite that is a DIB will be more sustainable and cost-effective in the long run.

Currently, Li-ion batteries possess one of the highest energy densities. While lithium batteries provide high energy, their size can remain smaller.

The mechanism used in DIBs will make them suitable for high-power applications using moderately high energy. This makes them useful in any high-energy storage application whether they are EVs or local utility systems. The size of the battery may not fit in mobile or other gadgets, though.

Challenges before DIBs

Despite the merits and practical applications of DIBs, there are still several negative issues that are hindering their adoption. These include limited capacity and cyclic stability, which triggers the development of suitable electrode materials. However, some strategies are being devised for further development of DIBs in the future.

DIBs can still hold a lot of energy, and if researchers are successful they can find a use for DIBs for electric vehicles and a good substitute for lithium-ion batteries.

Image credit: ©stock.adobe.com/au/Blue Planet Studio

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