Direct recycling of NMC-cathode scrap: Relithiation in aqueous solution following by low-temperature annealing

Abstract

With the rise of electric mobility, the growing demand for batteries is expected to generate a significant stock of end-of-life batteries, making recycling an interesting solution to reduce environmental impact. Here, we propose a direct regeneration process in two steps based on a hydrothermal relithiation and post-annealing at moderate temperature. Two NMC-materials went through chemical delithiation and subsequent relithiation: NMC from scrap, which is recovered with the conductive carbon from its original formulation and reference NMC for comparison. The results demonstrate that relithiation was effective during the first solution step, leading to a partially active material. The post-annealing treatment enhances electrochemical performances and the best ones are obtained for the samples annealed at 400 °C. Therefore, the results confirm that the presence of residual carbon does not impact relithiation or compromise its efficiency. The latter conserves its conductive properties after the relithiation process. However, an amount of the carbon has been lost during the second step; then this loss was compensated with an addition of fresh carbon, providing satisfactory electrochemical performances.