Understanding Solid-State Direct Recycling of Ni-rich Layered Positive Electrodes

With ever-increasing production volumes of lithium ion batteries (LIBs), the worldwide quantity of end-of-life (EoL) electric vehicle (EV) LIBs is expected to be 3.6 to 5.3 million metric tons until 2030. In order to meet legislative regulations, and reduce environmental and health risks, effective recycling strategies are crucial. Direct recycling, i.e. the direct reuse of battery components without breaking down the chemical structure, is a closed-loop approach allowing the reduction of costs, energy consumption and greenhouse gas emissions during recycling. Compared to well-known low- to mid-Ni layered oxides, LiFePO3 (LFP) and LiCoO2 (LCO), the promising Ni-rich layered oxides are supposed to be even more prone to severe morphological and structural degradation during charge/discharge cycling, making direct recycling particularly challenging. Here, spent cathode active material, i.e. LiNi0.83Co0.12Mn0.05O2 (NCM-831205), is directly recycled via re-lithiation and reconstruction. Re-lithiation is performed via a solid-state reaction with lithium hydroxide monohydrate under oxygen atmosphere at 800 °C, i.e. mimicking original synthesis procedures of pristine Ni-rich NCM. In the directly recycled powders, polycrystallinity and high tap density are maintained, and the evolution of particle size and shape, specific surface area, crystal structure at the surface and in the bulk, and lithium content, are explored. Pristine-original performance is reached for 100 cycles in graphite-based full-cells and remaining issues including possible strategies are highlighted. In summary, the current status of direct recycling is reviewed, presented experimental results are contextualized and economic feasibility is discussed. Figure 1