These researchers promise a chlorine battery with unprecedented efficiency

Li-SOCl2 batteries are known for their endurance, capacity, low discharge rate, but also for their main weakness: they do not recharge. Not long ago, American scientists said they had found a solution to recharge them.

Chlorine chemistry is not stable enough

Lithium thionyl chloride (Li-SOCl2) batteries are commercially available. Very durable, they also have a large capacity and a very low discharge rate compared to li-on batteries. Usually we find them in the industrial sector, more precisely in the equipment of long-term applications. Unfortunately, these batteries were not designed to recharge, a shame at a time when the ecological impact of devices is at the heart of all concerns.

It must be said that the chemistry of chlorine sorely lacks stability to allow charge (and discharge) cycles. However, lithium (or sodium) chloride is transformed into chlorine, a substance whose reactivity is too high to return to its basic state. Thus, Li-SOCl2 batteries face limits which in theory do not really make them a product of the future.

However, these limits could fall, as explained by researchers at Stanford University (United States) in their study published in the journal Nature on August 25, 2021. The team of scientists is currently experimenting with a way to stabilize the chemistry chlorine and thus allow the Li-SOCl2 batteries to be recharged.

Surprising promises

This solution is based on a new electrode, made of porous carbon. However, this carbon absorbs erratic chlorine molecules and stores them safely. The goal ? Convert these molecules back to sodium. Obviously, the project is still in its infancy, but the promises are high. Already, the battery on which the researchers are working allows 200 cycles of charge and discharge. However, it is a question of constant progress, despite the fact that we are still very far from the 500 to 1000 cycles allowed by conventional li-on batteries.

Stanford experimentation battery rechargeCredit: Stanford University

In a statement, the researchers say that the Li-SOCl2 battery in question will offer an energy density of 1,200 mAh per gram when recharged. However, this value is surprising and gives hope of multiplying by six the standard of the usual batteries currently equipping most of our everyday devices.

Obviously, there is still a long way to go. Going from simple experimentation to large-scale production usually takes several years. In the meantime, people with smartphones can dream of a future where everyone can charge their device only once a week.

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