With the rapid growth of electric vehicles in recent years, power batteries will usher in the first wave of decommissioning and recycling, and the promising battery recycling market is in urgent need of more cost-effective recycling technology.
Recently, Princeton university researchers have developed a low-cost, sustainable way to make new batteries from old batteries and founded a startup, Princeton NuEnergy.
Yan Chao, co-founder and CEO of Princeton NuEnergy and postdoctoral fellow in Princeton University's Department of Mechanical and Aerospace Engineering, said: "People are willing to give us idle waste batteries and receive new cathode raw materials from us to make new batteries, which is cheaper than making new batteries themselves. ”
The technique developed by the Princeton NuEnergy researchers combines expertise from different fields to solve a long-standing problem: how to convert discarded cathode materials or expensive materials containing elements such as cobalt, nickel, manganese and lithium in lithium batteries into new cathodes.
At present, the technology of recycling lithium batteries relies on harsh chemicals and high-temperature, high-energy intensive processes to break down waste batteries into elemental components. It has always been challenging for this process to scale up commercially and in an environmentally friendly way.
In contrast, Princeton NuEnergy upgrades and updates the positive electrode itself in the form of direct recycling. The team's method can restore most of the structure and composition of the used cathode, including cobalt and lithium. According to the researchers, this method of generating new cathode materials can reduce water consumption by about 70%, energy consumption and emissions by 80%.
The researchers held raw materials extracted from the recycling process
At the heart of this technology is the use of cryogenic plasma, an extremely reactive ionized gas that can be chemically reacted with to remove contaminants from the positive powder. Otherwise, handling these contaminants requires very high temperatures and breaks down the material in large quantities. The team can clean up the positive electrode material without destroying it by mechanically separating the positive and negative materials and passing the positive powder through a plasma reactor to remove contamination from the battery.
Conventional battery recycling techniques required the separation of individual elements by mechanically crushing and melting the battery material, or dissolving the battery in a strong acid. This type of acid-based technology produces a large amount of metal, which cancels out all the work originally used to produce the positive electrode. These methods are considered indirect because they simply break down the battery material into elemental components, rather than reconstructing it and regenerating it to generate a new battery material. Some lithium is lost from the cathode material during the life cycle of the used battery, so the research team added a small amount of lithium back into the recycled cathode powder to produce a material that is cheaper than the new cathode material.
"If you have a piece of dough, you can try gently kneading it and giving it a different structure, but basically leave it alone." Bruce Koel, co-founder and technical advisor at Princeton NuEnergy, explains, "You shouldn't destroy it or break it down into flour and butter. ”
At present, only about 5% of the waste lithium batteries in the United States have been recycled. According to Princeton University's U.S. Net Zero Study, trying to reach net zero emissions by the middle of this century means that the number of electric vehicles will increase from about 1 million today to 210-330 million. Electric vehicle batteries have a service life of 5-10 years, with about 3000 battery cells per vehicle (depending on the model). IHC Markit's analysis estimates that there are currently about 10 billion (about 465,000 tons) of used power batteries that need to be disposed of, and that number is expected to grow to 29 billion by 2025.
Given the boom in battery recycling, companies with competitive technologies are likely to emerge, and Princeton NuEnergy is looking to scale up production. Wistron Greentech, a Taiwanese-based company, recently launched a pilot project with which it is one of the technology companies' major waste processors.
Princeton NuEnergy is currently building a processing line at the company's Texas plant, which plans to ramp up production to at least one ton per day in 2022. A production line that was once used to recycle gold from printed circuit boards in electronics will be transformed into Princeton NuEnergy's battery recycling processing line. From gold to battery materials such as lithium and cobalt, this also reflects the transformation of current market demand.
"We think that applying this technology to a truly industrial project will be a huge opportunity that will allow us to recycle and reuse lithium batteries on a large scale." Yan Chao said.
Koel said expanding the scale of this technology can not only alleviate supply chain problems for imported minerals, but also reduce the demand for minerals in over-exploited areas, where environmental and labor problems are generally more serious. For example, cobalt, a key component of the positive electrode, is mostly produced in the Congo, where the mining industry has a large problem of child labor.
At present, the regenerative cathode developed by the team has excellent test performance in small coin cell batteries. The researchers hope to continue to improve recycling capacity within a few years and expand from consumer electronics batteries to electric vehicle batteries, and possibly even to the use of recycled materials to make full batteries.