Novel High-Capacity Composite Anodes for the Upcycling of Spent Graphite from End-of-Life Lithium-Ion Batteries

In terms of energy storage, lithium-ion batteries are the clear solution of choice for applications ranging from consumer electronics to electric vehicles and they will remain so for decades to come. Increasing demand for batteries is a concern because there are not enough raw materials available to support this projected growth. Further, battery-grade graphite, a key component of lithium-ion batteries, is almost exclusively supplied from foreign sources. The Vehicle Technologies Office has taken special interest in technologies that focus on mitigating global supply risk by establishing work based on three foundational pieces: (1) diversifying supply chains, (2) developing material and technology substitutes, and (3) promoting recycling, reuse, and efficiency. The proposed work addresses all three of these goals by upcycling low-value recycled graphite obtained from spent lithium-ion batteries into high-capacity, high-value anode materials for use in new batteries. Though recycling of batteries is currently performed by several companies, none of their recycling methods is optimized to provide graphite that is suitable for conversion directly to electrodes, due to the high cost of removing organic and inorganic impurities. The innovation represented by the proposed work is a process to utilize impure recycled graphite to create a new high-capacity anode material. The process uses a proprietary, low-cost, inorganic, resin-based technology to create conductive ceramics. Previous work by the proponent has shown that polymer-derived ceramics, which are the result of inert gas pyrolysis of ceramic-forming polymers, can be used to encapsulate impurities and inhibit their deleterious effects on graphite performance. In Phase I, previously obtained results will be used as a foundation to develop and demonstrate a viable process for producing high-performance graphite for use in battery anodes from recycled materials obtained from multiple different sources. Electrochemical performance of the developed anode composites will be characterized, with a focus on specific capacity and first-cycle efficiency. The best-performing composite anode will be used for feasibility studies in full cells with a capacity of greater than 225 mAh. The primary benefit of this work will be the ability to use recycled graphite (designated as a critical mineral), which until now, has not been deemed economically viable due to low purity and rejuvenation cost post-recycling. The concomitant reduction in dependence on foreign sources of a critical material is of interest for national security and supply chain issues. Further, use of recycled graphite through this process promises to require less energy and simplified manufacturing scale-up compared to other approaches. Beyond Phase I, the technology can be applied to larger batteries with the eventual goal of supporting recycling and reuse of materials from and for large market consumers such as electric vehicles.