For battery manufacturers, recycling design is not a priority, but solutions do exist. Recycling lithium-ion devices is technically feasible, but improving the business case is necessary before it can begin.
The increasingly serious challenges of lithium-ion battery recycling should be addressed at the design stage. To date, manufacturers have focused more on safety, power density, and recyclability.
Researchers from the University of Leicester, Newcastle and Birmingham, the Faraday Institute, the ReCell Centre and Argonne National Laboratory examined the product design and published their findings in “The Importance of Lithium-ion Battery Recycling Design,” a commentary published in Green Chemistry.
For any material to be circular, it is important to reduce the number of components, to have lower costs for secondary processes (recycling) compared to primary processes (raw material extraction), to have simple purification processes, to have valuable components, and to have collection and recycling isolation mechanisms. This will also be helpful if the material is not recycled, as this often necessitates recycling when the material has a significant environmental impact.
Lead-acid batteries meet these design requirements, which explains why recycling rates are close to 100% in Japan, the United States, and most of Europe, with recycling mechanisms recovering over 98% of the total battery mass.
The similar density values of the cathode and current collector in lithium batteries make such methods impractical. Therefore, lithium-ion devices rely on methods such as redox reactions, solubility, or the use of electrostatic and magnetic properties to separate the materials that make up the battery.
The lack of labeling is another major obstacle to an effective recycling system. Unlike lead-acid batteries, lithium-ion devices have a variety of chemistry and structures, such as NCA, NMC, LMO, LCO, and LFP batteries, all of which can be combined into different chemistry. Batteries can also come in pouch, prismatic, or cylindrical forms, which are then welded into modules and assembled into groups.
A UK-US research team stated that there are no global standards for battery labeling, and it's crucial to clearly indicate the equipment's composition to recyclers. As a result, hydrometallurgy—involving crushing and acid treatment—has become commonplace in lithium-ion battery recycling, replacing the energy-intensive smelting and pyrometallurgical processes preceding acid processing. Hydrometallurgy requires pretreatment, effluent disposal, and proper dismantling, rather than simply "crushing."
The arrangement of batteries and modules within a battery pack varies (sometimes even within a single EV manufacturer's fleet), presenting another hurdle for recyclers. The organization of lithium-ion devices comes at the cost of maximizing safety and battery life, but also at the expense of recyclability.
The higher the number of cells, the lower the proportion of active and valuable materials in the battery weight. The increased number of cells also complicates the opening and separation steps, adding to recycling costs. The Tesla Model S electric vehicle (EV) with an 85kWh battery pack contains 16 modules, each with 444 battery cells, for a total of 7,104 cylindrical battery cells per vehicle.
The authors of the paper in *Green Chemistry* wrote, "When dismantling is slow and costly, the only recycling method becomes pyrometallurgy, which is both expensive and inefficient. Therefore, recycling is in a 'capture 22' situation, where battery and battery pack design controls the recycling strategy."
Manually disassembling the packaging and modules to extract individual cells is the preferred method for recycling pure materials, but it takes much longer than shredding. The countless combinations of battery and battery pack designs exacerbate this delay, making automated disassembly virtually impossible.
Researchers suggest the battery may also feature a robust busbar instead of the flexible cables currently used to connect modules. Such a structure would allow cells to connect directly to the busbar without requiring modules, and would make it easier for robots to detach the cells from the busbar. Adding breakpoints or other opening mechanisms would further facilitate easier access to and separation of the cell components.
Researchers say that separating electrode materials without shredding them could reduce recycling costs by up to 70% compared to purchasing virgin materials. Anglo American states that comprehensive labeling, a simplified overall structure, an easy-to-open design, and reversible adhesives and binders will solve most of the lithium-ion battery recycling problems.
Scholars have also offered suggestions on how to formulate such regulations, suggesting that expanding manufacturers' responsibilities and obligations to recycle end-of-life products will prompt engineers to adopt a "recycling design" approach.
