A lithium-ion cell is a complex device that contains several valuable materials. Although cathode active materials recovery is the main focus of the program, recovery of other materials is also important and offers additional benefits. The “other materials” are defined here as electrolyte components, anode materials, and metals from current collectors.
It is important to design all down-stream processing and material recovery sequences in a way that preserves integrity and assures high salvage rate and quality of all recovered materials.
Graphite and lithium compounds (electrolyte salt) are two high-value materials that are defined as critical due to their limited supply or their geographical location. By recovering these materials, we will be securing a domestic source for them, therefore reducing our foreign dependence and increasing our national security.
Metals, particularly copper recovered from current collector, provide additional revenue. By recovering additional materials, the recycling process maximizes the reuse of lithium-ion cell components and therefore tightens the closed loop, driving the overall process to profitability.
The ReCell collaboration will focus on four key areas in Recovery of Other Materials:
- Cell pre-processing: Cell disassembly and size reduction is the critical first step in LIB recycling. We plan to investigate non-aqueous shredding methods that will not deteriorate materials to be recovered later in the recycling process. Safety of the process needs to be the top priority. It is also important to explore the effects of size and size distribution of shredded materials on separation efficiency.
- Electrolyte component recovery: Electrolyte must be removed from the electrode materials to allow for further recycling processes. This can be done in several ways, including extraction with supercritical CO2, thermal drying, water washing, and solvent extraction. Of these only supercritical CO2extraction with added co-solvent or solvent extraction can recover the LiPF6, which is the most valuable component of the electrolyte.
- Solvent based delamination: The new processes to separate active material powders from current collector foils use green solvents. These are inexpensive, nontoxic, and do not cause water and/or air pollution, nor do they incur a penalty in terms of damage to active materials and current collectors. The recovery of cathodes and anodes from spent cells has high peeling-off efficiency and is cost effective, scalable, energy efficient, and environmentally friendly.
- Anode/Cathode separation: Anode material, not currently recovered, represents approximately 10% of initial cell material cost. This project will separate and recover usable anode material from black mass. Efficient production of multiple clean material streams (cathode, anode, and aluminum and copper foils) and avoiding waste disposal costs will make direct recycling more profitable.
Learn more about the individual projects in these areas in our Quarterly Reports.