New technology hopes to promote the recycling of lithium batteries

One of the difficulties faced by lithium battery recycling is that the cost of the material itself is low, and the cost of the recycling process is not low. A new technology hopes to promote the recycling of lithium batteries by further reducing costs and using environmentally friendly ingredients.

A new processing technology that restores the used cathode material to its original state can further save the recycling cost of lithium-ion batteries. The technology was developed by nanoengineers at the University of California San Diego (University of California San Diego) and is more environmentally friendly than the methods used today. It uses more environmentally friendly ingredients, reducing energy consumption by 80% to 90%, while reducing greenhouse gas emissions by 75%.

In a paper published in 'Joule' on November 12, the researchers introduced the results of this research in detail.

For cathodes made of lithium iron phosphate (LFP for short), the effect of this treatment technology is particularly ideal. LFP cathode batteries are cheaper than other lithium-ion batteries because they do not use precious metal materials such as cobalt or nickel. The service life of LFP batteries is also longer and safer. They are widely used in power tools, electric buses and power grids. Tesla Model3 also chose LFP batteries.

'In view of the above advantages, LFP batteries will have a competitive advantage over other lithium-ion batteries on the market.' said Zheng Chen, professor of nanoengineering at UC San Diego.

Is there any problem? 'The recycling of this kind of battery is not cost-effective.' Chen said, 'It is in the same dilemma as plastics-the material itself is very cheap, but the recycling method is not cheap.'

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The new recycling technology developed by Chen and his team can reduce these costs. This technology can work at low temperatures (60 to 80 degrees Celsius) and ambient pressure, so it consumes less electricity than other methods. In addition, the chemicals it uses, such as lithium salt, nitrogen, water, and citric acid, are cheap and mild in nature.

PanpanXu, the first author of the study and a postdoctoral researcher in Chen’s laboratory, said: “The entire process of reuse is carried out under very safe conditions, so we do not Any special safety precautions or special equipment. This is the reason why our battery recycling cost is low.'

First, the researchers repeatedly recycle the LFP battery until the battery loses half. Energy storage capacity. Subsequently, they disassembled the battery, collected the cathode powder in it, and soaked it in a solution containing lithium salt and citric acid. Next, they washed the solution with water and heated it after the powder was dry.

Researchers used these powders to make new cathodes, which were tested in both coincell and pouchcell. Their electrochemical properties, chemical composition and structure are completely restored to their original state.

As the battery continues to be recycled, the cathode will undergo two important structural changes, resulting in its performance degradation. The first is the loss of lithium ions, which creates cavities in the cathode structure. Secondly, when iron ions and lithium ions in the crystal structure exchange positions, another structural change occurs. Once this change occurs, the position of the ion can no longer be easily switched back, so the lithium ion will be trapped and can no longer circulate in the battery.

The treatment method proposed in this study first replenishes lithium ions, allowing iron and lithium ions to easily switch back to the original site, thereby restoring the cathode structure. The second step is achieved by using citric acid, which acts as a reducing agent and can provide electrons to another substance. It transfers electrons to iron ions, reducing the positive charge it carries. This minimizes electron repulsion, prevents iron ions from moving back to the original position in the crystal structure, and releases lithium ions back into the circulation.

Although the total energy consumption of this recycling technology is lower, the researchers said that further research is still needed to understand the logistical issues of collecting, transporting, and disposing of a large number of batteries .

'The next challenge is to figure out how to optimize these logistics processes.' Chen said, 'This will bring our recycling technology one step closer to industrial applications.'