Aerosol monitoring of ultrafine particles and airborne carbon nanotube release during mechanical recycling processes of nanomaterial-containing lithium-ion batteries

Mechanical processing of lithium-ion batteries (LIBs) can unintentionally release ultrafine particles (UFPs), including carbon nanotubes (CNTs), raising occupational health and nanosafety concerns. This study presents an aerosol measurement approach during the comminution of nanomaterial-containing LIBs, using the example of LiFePO4 cells. OPS and SMPS were used to measure the size of airborne nanoparticles over a range of three orders of magnitude. This was complemented by nanofibre-specific sampling and Raman-based Identifier C2 analysis for CNTs, enabling the differentiation between single- and multi-wall CNTs. Shredding (<1 cm) and milling (<0.5 mm) led to both UFP and CNT release, resulting in number concentrations below 1000 particles per cm3. However, particle counts alone were insufficient to assess CNT exposure, necessitating selective, chemistry-specific monitoring of respirable CNTs. This laboratory study demonstrates that CNT concentrations can exceed the recommended limit of exposure of 1 µg/m³, underscoring the need for CNT-specific monitoring and method validation, particularly in industrial manufacturing and recycling settings of emerging battery technologies. Mechanical recycling of lithium-ion batteries can release ultrafine particles and carbon nanotubes, posing occupational health and safety concerns. Here, the authors developed and validated an aerosol monitoring approach to simultaneously detect and quantify ultrafine particles and airborne carbon nanotubes released during lithium-ion battery comminution.