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• Article
• Published: 02 December 2021

A non-flammable hydrous organic electrolyte for sustainable zinc batteries

A non-flammable hydrous organic electrolyte for sustainable zinc batteries | Nature Sustainability

Abstract

Aqueous zinc (Zn) batteries have long been considered a potentially more sustainable alternative to lithium-ion batteries because of their better environmental compatibility, enhanced safety and cost advantage. However, in the presence of an aqueous electrolyte, the Zn anode is poised to undergo dendrite failure, corrosion and hydrogen evolution, all of which resonate with each other leading to fast performance degradation. Here, in a break from the current aqueous battery path, we report a low-cost hydrous organic electrolyte involving a hydrated Zn(BF₄)₂ salt and an ethylene glycol solvent, which not only promotes the in situ formation of a favourable ZnF₂ passivation layer to protect Zn from dendrite growth and side reactions but also embraces excellent non-flammability. Remarkably, the present Zn anode sustains a long-term cycling over 4,000 h at a current density of 0.5 mA cm⁻² with a high Coulombic efficiency of 99.4% and shows an areal capacity as high as 5 mAh cm⁻². Equally intriguingly, the electrolyte can run across a wide temperature range from −30 °C to 40 °C without seriously compromising performance. The Zn//V₂O₅ full cells with our electrolyte also perform much better in terms of capacity retention than a device with an aqueous ZnSO₄ electrolyte. Our findings suggest a promising direction for developing electrolyte solutions for practical Zn batteries which combine safety, performance and sustainability.

Move over Lithium, Zinc batteries are here | by Vineeth Venugopal | Mar, 2022 | Medium

Move over Lithium, Zinc batteries are here

New development promises a new age of Zinc batteries

Zinc batteries are often touted as promising alternatives to Lithium batteries (as are Sodium, Potassium, and a bunch of others).

However, they suffer from a number of problems — one of which is that very thin needle-like structures start forming from the electrode and grow into the electrolyte. At some point, they will short circuit the battery, effectively making it useless.

(Lithium batteries also have this problem).

The other issue with Zinc batteries is that they react with water in the electrolyte releasing hydrogen.

But they also have many advantages — such as high energy density, and specific capacity — due to which we keep trying to make them work.

Now researchers in China have come up with a solution in the form of a new organic electrolyte that is made from ethylene glycol and zinc tetrafluoroborate hydrate (Zn(BF4)2).

They form a ZnF2 protective layer that guards against needle formation (technically called dendrites).

The layer also suppresses side reactions.

The resulting hydrous Zn(BF4)2/EG electrolyte is non-flammable and works over a wide temperature range, from -30°C to 40°C.

The electrode can be cycled for over 4000 hours at a current density of 0.5 mA/cm2 and Coulombic efficiency of 99.4%.

This could be the beginning of a new set of safe, high-performance, and sustainable batteries.

cheers.