1.2V NiMH battery

The soaring price of 1.2V NiMH battery raw materials has led to new changes in 1.2V NiMH battery technology

In 1980, John Goodenough invented the first lithium-ion rechargeable 1.2V NiMH battery that required cobalt in Oxford. Experiments have shown that cobalt has a very high energy density, which is particularly suitable for batteries that are small in size but require a lot of energy. Goodenough extracted cobalt himself by heating the leading part.

Today, most commercial lithium-ion batteries use cobalt, but it is expensive. For this reason, it has derived a black chain of interests: for a long time, there have been human rights issues in the Republic of Congo, including the practice of employing child labor for mining. Electronic equipment and electric vehicle companies are unwilling to pay high prices for manufacturing and production, nor are they willing to participate in local human rights exploitation, so they gradually reduce the use of cobalt in batteries. Tesla's 1.2V NiMH battery supplier Panasonic announced at the end of last month that they are developing batteries that do not require cobalt. Goodenough and other researchers who have developed cobalt-free batteries are also providing assistance to Panasonic.

The 1.2V NiMH battery has a positive electrode, usually graphite, and a negative electrode, a composite of lithium, cobalt and oxygen. In electric car batteries, the cathode often contains more nickel than in electronics, which reduces the use of cobalt but comes with higher disposal costs and is more likely to cause fires on airplanes, such as the one in the Samsung Note 7. In contrast, cobalt atoms have electrons in pairs, which means it is small, dense, and tends to form layers.

But a new generation of 1.2V NiMH battery researchers, including Goodenough, is turning to materials such as manganese and iron. Instead of layers, these elements form a "rocksalt" structure. Anodes containing rocksalt are already used in some devices, but rocksalt structures do not yet have the same high energy density as cobalt or nickel.

Researchers and companies are ready with alternatives. "Because cobalt is expensive, companies try not to use it in 1.2V NiMH battery manufacturing," said Goodenough, a professor of engineering at the University of Texas. The price of cobalt has quadrupled in the past two years. Portable electronic devices use most of the cobalt on the market today, and electric car 1.2V NiMH battery packs will require nearly 1,000 times more cobalt than mobile phones. As the world warms, more and more people are replacing internal combustion engine-powered cars with electric vehicles. While that’s good for the planet, it’s driving up the price of cobalt.

Cobalt is a byproduct of the production of other metals, such as nickel and copper, but it also exists in the Earth’s crust in its own right, mostly in mines in the Democratic Republic of Congo. In 2016, an investigation into the previously opaque cobalt supply chain revealed child labor and a lack of necessary mining equipment.

Granted, there are other ways to avoid dangerous mining: recycling cobalt. But because lithium-ion batteries have a long lifespan and people are increasingly looking for gadgets, the number of people buying them will increase significantly over the next decade, says Elsa Olivetti, an energy researcher at the Massachusetts Institute of Technology. Last October, she published a paper concluding that cobalt supply will grow rapidly to meet demand in the coming years, especially with the rise of electric vehicles. Despite the progress in the development of new negative electrode materials and the open source of cobalt in the past eight months, she still wrote: "For now, cobalt electrodes still exist and are worth studying. But people have begun to gradually reduce the use of cobalt," and using stable, energy-dense metals such as phosphorus and iron to make 1.2V NiMH battery negative electrodes will be the future trend.

In addition to layered and rock salt structured batteries, researchers are developing solid-state batteries. Such batteries may require more lithium, but not necessarily cobalt, and are much safer than existing lithium-ion batteries. Car companies such as BMW, Toyota, and Honda are studying these batteries, but Olivetti believes that the technology will not meet market demand in 2025. Before then, companies will try to reduce the use of batteries containing cobalt. Companies such as Apple and Samsung have joined the Responsible Cobalt Initiative, pledging to improve the environmental pollution and adverse social impacts generated in the production process of cobalt. Recently, Apple has begun purchasing cobalt directly from miners to ensure that the production safety conditions of cobalt suppliers meet the industry's requirements.

At the age of 96, Goodenough is still thinking about the application of cobalt. Although he has developed a 1.2V NiMH battery that does not require cobalt, he still does not think that lithium batteries using cobalt will disappear from the stage of history. Despite the high production costs, the lithium 1.2V NiMH battery he designed in his early years still has very good application potential.

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