The Sure Bet
But here is the rub—recycling has some real advantages over mining virgin ores for use in batteries. Mining is a form of gambling. Mining companies use explosives and fossil-fuel-powered heavy equipment to extract ore from the ground. They then crush the ore and subject it to powerful acids to pull out the desired metals, which must be further chemically treated and purified. The waste materials left behind must be separated from the acids and then stored indefinitely as tailings and spoils. The mining bet is that the ore will contain enough of the desired metals (usually in several hundred parts per million) to make the extraction process profitable.
Recycling, on the other hand, is a sure thing. The amount and quality of each of the desired metals are precisely known, based upon the feedstock of spent batteries that are being recycled. The concentrations of the materials in the feedstock is akin to that of a highly enriched ore. It may not be easy to extract the desirable materials from the battery cells, but the amount of return is easy to establish and, unlike mining, the profits don’t vary based upon the feedstock that is coming out of the ground.
It Isn’t Easy
Not that recycling lithium-ion batteries is particularly easy. Lithium-ion batteries are not designed to be disassembled and, as the need for higher energy density to create better vehicle range has increased, cells have become increasingly compact and are constructed in a variety of shapes and sizes. Battery packs also contain wiring (usually copper), sensors, and circuit boards that are part of battery management systems.
There are several accepted ways to recycle lithium-ion batteries. Pyrometallurgy facilities use a high-temperature melting-and-extraction, or smelting, a process that is similar to ones used in the mining industry. Furnaces run near 1,500 °C, recovering cobalt, nickel, and copper, but not lithium, aluminum, or any plastic and organic compounds, which burn away. It is an expensive process, in large part due to the need to treat the emission of toxic fluorine compounds released as gases during the burning of the electrolytes and plastic materials.
A chemical leaching process, called hydrometallurgy extracts and separates cathode metals below 100 °C and can also recover lithium and copper, and other transition metals. Hydrometallurgy is practiced commercially in China and is a less energy-intensive alternative with lower costs, but the need for caustic reagents such as hydrochloric, nitric, and sulfuric acids, and hydrogen peroxide, increasing environmental issues.
Early in 2019, the US Department of Energy (DOE) started its ReCell Advanced Battery Recycling Center, headquartered at Argonne National Laboratory. ReCell includes some 50 researchers based at six national laboratories and universities, and includes battery and automotive equipment manufacturers, materials suppliers, and other industry partners.
The ReCell team is investigating direct recycling methods for recovering and reusing battery materials without costly processing. One approach calls for removing the electrolyte by freezing it with supercritical carbon dioxide, then crushing the cell and separating the components physically. This can be done based on density differences. According to information from ReCell, “Direct recycling is the recovery, regeneration, and reuse of battery components directly without breaking down the chemical structure. By maintaining the process value in the original battery components, a lower-cost re-constituted material can be supplied to battery manufacturers. This will in turn help reduce the cost of EV batteries and drive up the value in recycling EV batteries.” The direct process also avoids acids and harsh reagents, making it more environmentally viable.
It’s important to remember that materials aren’t used up inside a battery. The recycled metals can be reused in a new battery without any reduction of quality or performance. The expensive battery materials for the cathode can even be supplied in a form that allows them to be used in new battery production with very little additional processing.
Planning for the Future
One observation from ReCell and other recycling research is the need to design future lithium-ion battery cells with recycling in mind. Presently, the push for maximum energy density, charging speed, and low-cost has hindered the growth of lithium-ion battery recycling.