The role of electrochemistry in the direct recycling of lithium-ion batteries

The increasing demand for lithium-ion batteries, driven by their widespread use in electronic devices and electric vehicles, has raised concerns regarding their recycling and end-of-life management. Batteries contain valuable and potentially hazardous materials, necessitating efficient recovery strategies. In this context, direct recycling has emerged as a promising approach, enabling the regeneration of cathode active materials (CAMs) for reuse in new batteries, with reduced energy consumption and minimal environmental impact. Among recycling strategies, electrochemical methods stand out for their efficiency in recovering critical materials via electrodeposition or ion insertion, generating minimal waste and reducing reagent consumption. In this work, the CAM from NMC-type lithium-ion batteries (Li₁Ni₀.₆Mn₀.₂Co₀.₂O₂, NMC622) was re-lithiated using chronopotentiometry as the electrochemical technique. The re-lithiation process was systematically optimized by evaluating the effects of lithium salt concentration, applied current density, temperature, and stirring conditions. After lithium insertion, the material underwent a heat treatment at 600 °C to restore its original crystalline structure. X-ray diffraction (XRD) analysis confirmed that the regenerated CAM recovered the characteristic layered structure of commercial NMC622, with matching peak positions. Analysis of the I₀₀₃/I₁₀₄ intensity ratio revealed an increase in Li–Ni cation mixing compared with the pristine reference, indicating that while the global layered structure was restored, some degree of internal disorder remained. These results highlight the potential of electrochemical re-lithiation as a sustainable strategy for the recovery and regeneration of degraded lithium-ion cathodes, contributing to circular economy approaches in battery materials management.