Lithium Supply: Could Recycling Be the Answer?

Electric car manufacturers will require an estimated 100,000 tons of lithium carbonate by 2021 to build lithium-ion (Li-ion) batteries. Establishing a reliable, diversified supply of lithium is a top priority for battery suppliers and vehicle manufacturers as well as other technology companies in the United States and Asia. The demand is growing at such a rapid rate that, according to an article on Industrial Minerals, experts say that a new lithium project needs to come online each year for the next few years.

Could recycling be part of the solution? The IM article explains that Li-ion battery recycling is uneconomical because lithium accounts for a relatively small proportion of the cost of the battery. Also, the expense of separating out a small quantity of lithium from recycled batteries, while possible in some situations, is not justified by the value of lithium gained.

At the 2016 International Battery Recycling Congress, noted speaker Alain Vassart, Secretary General of the European Battery Recycling Association (EBRA), described a number of conditions that must be met before a recycling loop for lithium can be established. These include a sufficient, constant flow of recyclable material, economically viable and competitive recycling processes, and a high price level for lithium for a stable time period in order to justify the cost of recycling.

Despite these challenges, technologies to recycle lithium are being pursued. Researchers at Worcester Polytechnic Institute (WPI) have developed a process for recycling Li-ion batteries and the production of new plug-in hybrid electric vehicle (PHEV) battery cells using the recovered cathode material. According to an article on the WPI web site, the process works with any cathode chemistry, meaning that no—or minimal—sorting is required. Commercially produced Li-ion batteries use a variety of chemistries for their cathodes, requiring recyclers to sort the batteries to avoid mixing incompatible formulations. This labor-intensive and expensive process is complicated by the difficulty of identifying the exact material used in a given battery. In the new process, the batteries are shredded and the steel, aluminum, iron, copper, and plastics are recovered and recycled. The cathode materials, lithium (Li), nickel (Ni), manganese (Mn), and cobalt (Co), are recovered and used to synthesize new cathodes with the formula LiNixMnyCozO₂. The ratio of Ni, Mn, and Co can be adjusted based on industry needs.

While lithium recycling is in the experimental stages, current efforts focus on improving the performance of Li-ion cells, for example to increase energy density, reduce weight, decrease costs, and improve recharge times. Understanding the solid-electrolyte interphase (SEI) layer on the electrodes, which is created as the cell charges and discharges, is an important part of this research. The formation and development of the SEI layer competes with the reversible lithium intercalation process, and over the lifetime of the battery the presence of the SEI will contribute to the lowering of capacity, and is a contributing factor to the ultimate failure of the cell. Controlling the SEI layer can improve cell performance. XPS depth profiling offers a way of chemically characterizing the complex mix that makes up the interphase layer, allowing an identification of the chemistries that comprise the SEI. Read Analysis of Electrode Materials for Lithium Ion Batteries describing the use of an XPS system to investigate unused and cycled cathode samples and determine variations in lithium content.