Over the last couple of years, lithium and its use in rechargeable batteries has taken the mining industry by storm. 

It has become the veritable must-have commodity and its position in the resources community looks set for the immediate future at least.

Lithium-ion batteries are used in a number of everyday items, including mobile phones, electric cars, laptops and cameras, though there have been instances of safety concerns surrounding them, showcased last year when a number of Samsung Note 7 smart phones burst into flames within weeks of their release to the public.

Other issues with the batteries include the cost of production and the limited lifespan before they lose recharge capacity, although estimates put this time at around three years for a standard mobile phone battery, exceeding the typical cycle of model updates from manufacturers.

With there being some issues with the current king of the battery world, the question needs to be asked; are there are any contenders to the throne?

Pursuit Minerals seems to think so, releasing a statement in September 2017 suggesting zinc could be at the heart of the next mining boom in Queensland.

The company’s reasoning stemmed from research into Zinc-bromine (Zn-br) and Zinc-air (Zn-air) batteries. Both of these products are cheaper to produce and have the potential for better longevity than Lithium-ion, and research suggests they will not have the same safety issues.

“Ultimately, both Zn-br and Zn-air batteries have better cycle rates, better energy retention and could be better in the longer term, so I think it’s going to be a development that needs to be looked at,” Pursuit Minerals Managing Director Jeremy Read told National Mining Chronicle.

In America, EnZinc is producing a third type of rechargeable zinc battery. Under an award from the US Advanced Research Projects Agency-Energy, and working with the US Naval Research Laboratory, which developed the technology, EnZinc has developed a zinc metal sponge.

This sponge structure allows the battery to charge and discharge without dendrite growth, allowing the creation of a zinc battery equivalent to lithium-ion batteries, but at a cost more like a lead acid battery, and safer than both, according to EnZinc Founder Michael Burz.

Zn-air batteries have actually been in the battery market since the 1930s, used in hearing, medical and railway signal devices, but as they are a primary battery they can only be used once.

University of Sydney Faculty of Engineering and Information Technologies Professor Yuan Chen said research was being done to achieve the rechargability of Zn-air batteries.

“In order to recharge Zn-air batteries, we need to inverse the reaction to turn zinc oxide into zinc and release oxygen during recharging,” he said. “People have used expensive platinum and iridium oxide catalysts to achieve this, but there are limited such precious metals on Earth.

“Our research is to develop high-performance, bi-functional oxygen catalysts which can reduce oxygen during discharge of Zn-air batteries and generate oxygen during charging.”

Once the rechargability of the Zn-air batteries is fully developed, Professor Yuan Chen foresees Zn-air batteries as being a more sustainable and cost-effective energy storage system than Li-ion batteries.

“Theoretically, their energy density is five times larger than current Li-ion batteries, meaning they can last longer,” he said. “Zinc is more stable in the air compared to lithium, so your batteries won’t catch fire so easily. Zinc is also much cheaper than lithium, so the batteries will become cheaper.

“It took more than 20 years to develop lithium-ion batteries into successful commercial products. We hope to see commercial rechargeable Zn-air batteries in 10 years.”

Another tick for zinc’s cause is its ubiquity. Mr Burz said it was the fourth-most mined metal on the planet. 

“If zinc-based batteries were used for all the gas-powered cars and all the electric vehicles produced last year, it would have used only four per cent of the world’s annual zinc production,” he said.

On the flip side, over the last couple of years there has been a zinc production deficit.

Mr Read said this year and next year were predicted to produce similar results, meaning the stockpiles of zinc were being eroded at a rapid rate.

“The issue is a lot of the predictions for the supply and demand for zinc going forwards don’t take into account any significant use of zinc with the emerging energy sector,” he said.

“Our market is so finely tuned at the moment, a small disruption in terms of increased consumption into the new technology could have a disproportionately large effect on the price cycle.”

Issues with zinc?

Although the benefits of zinc appear to be many, there are a couple of issues that need to be ironed out if zinc-based batteries are going to pose a serious threat to the current rechargeable battery king.

One such issue is the power density zinc-based batteries are currently able to produce. The voltage capacity is around 1.6V, similar to alkaline batteries, while lithium-ion batteries produce 3.4V. This means zinc-based batteries would need a battery pack with more cells. 

This, combined with struggles with energy per unit volume or watt hours per litre, is why Mr Burz said the best usage for zinc-based batteries was in larger products like cars or grid storage.

“For very small devices like cell phones, Li-ion is better. But for larger products where large amounts of energy require lithium batteries to have auxiliary sub-systems added to the battery to control the temperature and ensure safety, then the zinc battery is competitive,” Mr Burz said.

Ultimately, whether zinc-based batteries are able to overcome the lithium-ion kingpin remains to be seen, and there will need to be a lot more research into the technology before the outcome is clear.

Mr Read said the discussion about whether lithium-ion or zinc-based batteries were a better alternative would happen and be resolved in the next couple of years.

“Personally I think it will happen a lot more quickly than people expect,” he said.

“I think we’re in the midst of the start of an energy revolution. There’s no doubt in my mind that over the next decade, how energy is produced, transmitted, stored and used is going to become fundamentally different to what it is now.

“There will be a number of technologies that will emerge out of that as the preferred ways of storing and moving energy around, and we hope zinc will have a fair part to play in that going forwards.”