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Using alternative materials could help reduce the mining of lithium and other minerals for battery manufacturing
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- Author: Chris Baraniuk
- Roll, BBC Future
November 25, 2023
But on a street in India, a bank selfservice machine continues to work fine and distributes money to people. Thanks in part to the burning cotton.
This machine has a backup battery that contains carbon from carefully burned cotton.
“The specific process is a secret, to tell the truth,” says Inketsu Okina, head of intelligence at Japanese battery maker PJP Eye.
And he’s not kidding. “The temperature is a secret and the atmosphere is a secret. The pressure is a secret,” he continues cautiously.
Okina says it is necessary to reach a high temperature more than 3,000°C. And that 1kg of cotton produces 200g of carbon. Since each battery cell requires only 2g, the company’s batch of cotton purchased in 2017 is still used today, he said.
Batteries consist of three basic components: two electrodes and an electrolyte in between.
One of the electrodes becomes positively charged and is called cathode, while the electrode with negative charge is called anode.
During use, charged particles called ions flow through the electrolyte from the anode to the cathode. This flow allows electrons to move along the wires of the circuit connected to the battery.
In the batteries that PJP Eye developed with researchers at Kyushu University in Fukuoka, Japan, carbon is used to form the anode one of the two electrodes between which the ions, the charged particles in the batteries, flow.
Ions move in one direction when charging a battery and in the opposite direction when operating a device.
Most batteries use graphite as an anode, but PJP Eye argues its approach is more sustainable because anodes can be made from cotton waste from the textile industry.
With huge demand for batteries expected in the coming years, driven by the rise of electric vehicles and largescale energy storage systems, researchers and companies have been frantically developing potential alternatives to today’s common graphite and lithiumion batteries.
Like PJP Eye, they argue that we could use much more sustainable and readily available materials for battery production.
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The increasing demand for electric vehicles requires the development of sustainable materials to produce batteries
Environmental damage
Lithium mining can have significant environmental impacts. Extracting the metal requires large amounts of water and energy and the process can leave large traces in the ground.
Recovered lithium is often transported long distances from the mining site to be refined in countries such as China. And graphite is also extracted from nature or made from fossil fuels, both of which have negative impacts on the environment.
“It’s very easy to imagine how large the carbon footprint could be when mining and transporting battery material,” said Sam Wilkinson, analyst at market intelligence and analytics firm S&P Global Commodity Insights.
Another example is cobalt, which is used in many lithiumion batteries. The metal is predominantly mined in the Democratic Republic of Congo and there are reports of dangerous working conditions in that country.
From seawater to organic waste to natural pigments, there is a long list of possible natural alternatives that are much more readily available. The hard part is proving that they can actually compete with the batteries on the market that seem so essential in our world full of devices.
PJP Eye also suggests the possibility of improving battery performance and making it more environmentally friendly.
“The surface area of our carbon is larger than that of graphite,” says Okina. He describes how the anode chemistry of his Cambrian brand singlecarbon battery enables charging up to ten times faster than existing lithiumion batteries.
The battery’s cathode is made of a “base metal” oxide. Okina doesn’t say exactly what this metal is, but it includes copper, lead, nickel and zinc, which are easier to extract and less reactive than alkali metals like lithium.
The company says it is developing a dual carbon electrode battery where both electrodes are made of plantbased carbon. The technology is based on research by researchers at Kyushu University, but the battery is not expected to be available until 2025.
The ability to quickly charge a battery doesn’t make much of a difference for a bank selfservice machine, but for electric vehicles it is important if you want to refuel to continue your journey.
Okina mentions that the Chinese company Goccia, in collaboration with the Japanese company Hitachi, has developed an electric bike with a PJP Eye battery that is available for sale in Japan. Okina states that the bike’s top speed is 50 km/h. h and you can travel a distance of 70 km on a single charge.
But it is far from the only battery that uses carbon from biowaste. Stora Enso in Finland has developed a battery anode that uses carbon from lignin, a binding polymer found in trees.
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Lithium mining causes severe environmental damage and often alters the entire local landscape
Cotton can also be used in place of the electrolyte that allows ions to flow between the cathode and anode, potentially creating solidstate batteries that are more stable than those available today, according to some researchers.
But there are those who imagine larger and potentially inexhaustible sources of energy in nature.
According to Stefano Passerini, deputy director of the Helmholtz Institute in Ulm, Germany, the planet’s vast oceans represent a “virtually unlimited” supply of battery material.
He and his colleagues, in a paper published in May 2022, described the design of a battery that transfers sodium ions from seawater to build a deposit of the metal sodium. To do this, the team designed a special polymer electrolyte from which sodium ions can pass.
Here, seawater acts as a cathode or positively charged electrode. However, there is no anode because sodium does not acquire a negative charge. It only accumulates in neutral form.
Passerini says excess solar or wind energy can be used to accumulate sodium, which can remain there until needed.
“If you need the energy, you can reverse the process and generate electricity,” he explains, describing how the metal would simply be returned to the ocean.
However, there are difficulties with this process. In short, sodium, much like lithium, reacts energetically when it comes into contact with water. In Passerini’s words: “They’re having a lot of fun.”
It is therefore essential to ensure that no seawater enters the sodium deposit to prevent a catastrophe.
This possibility led other researchers to look for a material that occurs naturally in our bones and teeth, among many other sources, as a safer alternative to cathodes: calcium.
For example, it can be combined with silicon to help transport calcium ions to future batteries.
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Electric vehicles and energy storage systems are expected to drive demand for batteries in the coming years
The list of materials that could power batteries in the future is getting stranger and stranger.
George John of the City University of New York in the United States and his colleagues have long been researching the potential of biological pigments called quinones, found in plants and other organisms, for use as battery electrodes.
They even had promising results with a molecule derived from henna the dye used in tattoos, which is derived from the henna tree Lawsonia inermis.
“This is our dream,” says John. “We want to produce a sustainable battery.”
One of the obstacles, in his opinion, is the strong solubility of the natural henna molecule. When used as a cathode, it gradually dissolves into a liquid electrolyte.
But by combining four henna molecules and adding lithium, John explains, it is possible to create a recyclable material with a much more resilient crystal structure.
“As crystallinity increases, solubility decreases,” he explains.
John adds that the battery designs he and his colleagues have developed may not have enough capacity to power electric vehicles, but one day they could be used in small portable devices perhaps for measuring blood sugar levels in diabetics or other indicators, for example .
Other researchers are exploring the use of various materials, such as corn waste and melon seed rinds, to create novel battery electrodes. However, the challenge could be to produce on a large scale to meet the industry’s increasing demand.
In fact, the ongoing challenge for any alternative battery material is always to meet the expected extraordinary increase in demand.
If we continue to use today’s lithium and graphite battery technology, the world will need around two million tons of graphite per year by 2030 to satisfy the growing battery industry, according to estimates by analyst Max Reid of the consulting firm Wood Mackenzie.
Currently annual consumption is 700,000 tons.
“Demand will actually triple,” he says. This is partly why alternatives to graphite must meet this high standard. “It will be incredibly difficult for any new material to reach this scale.”
According to engineer and battery scientist Jill Pestana from California, USA, who currently works as an independent consultant, changing manufacturing processes and abandoning graphite would be very costly and potentially a major commercial risk.
She is skeptical about using biowaste for carbon anodes because the sources of this waste may not always be very environmentally friendly. This is the case, for example, in a tree plantation with poor biodiversity management.
On the other hand, in markets where consumers are clearly concerned about the sustainability of the products they purchase, alternative battery materials from appropriate sources may have a greater opportunity regardless of whether the batteries are made from carbon derived from biowaste or other possible materials becomes more sustainable substance.
“The public can play an important role and really drive these efforts forward,” Pestana emphasizes.