Observing electrolyte motion in commercial cylindrical Li-ion cells using ultrasound imaging

Journal of Power Sources, vol. 671, pp. 239455

Abstract

Cylindrical Li-ion cells, increasingly adopted in electric vehicles, pose geometry-driven challenges for scanning acoustic microscopy (SAM). While SAM for flat cell formats is well established, spatial ultrasound imaging of cylindrical cells is under explored. We present a compact rotational ultrasound scanner that leverages cylindrical symmetry to generate two-dimensional angle–height images in both through-transmission and reflection using two opposing single-element transducers. To our knowledge, this is the first rotational ultrasound system that provides through-transmission imaging of cylindrical Li-ion cells and the first single-element reflection images that can be directly linked to large-scale internal structures such as current collector tabs. Early-time gating of the first arrival (through) and late gating of the first front-wall echo (reflection) suppresses circumferential and creeping waves, restoring interpretable contrast. We validate the platform on aluminum reference dummies and demonstrate spatial imaging on three 26650 cells. The scanner produces interpretable angle–height maps in through-transmission and reflection that localize tabs, reveal orientation- and state-of-charge dependent electrolyte redistribution, and highlight stable attenuation features linked to internal mechanical conditions. Co-registration with X-ray CT provides a common angular frame and anchors acoustic contrasts in the underlying structure, establishing ultrasound as a practical complement to existing battery Non-destructive testing (NDT).

Authors 6

1. Tobias Röhmel corresponding Aachen Center for Ageing Chair for Electrochemical Energy Conversion and Storage Systems Institute for Power Electronics and Electrical Drives (ISEA)

   Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Center for Ageing, Reliability and Lifetime Prediction for Electrochemical and Power Electronic Systems (CARL), RWTH Aachen University, Campus-Boulevard 89, Aachen, 52070, Germany

   Chair for Electrochemical Energy Conversion and Storage Systems, Institute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University, Campus-Boulevard 89, Aachen, 52074, Germany

   Jülich Aachen Research Alliance, JARA-Energy, Templergraben 55, Aachen, 52056, Germany

2. Morian Sonnet Aachen Center for Ageing Chair for Electrochemical Energy Conversion and Storage Systems Institute for Power Electronics and Electrical Drives (ISEA)

   Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Center for Ageing, Reliability and Lifetime Prediction for Electrochemical and Power Electronic Systems (CARL), RWTH Aachen University, Campus-Boulevard 89, Aachen, 52070, Germany

   Chair for Electrochemical Energy Conversion and Storage Systems, Institute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University, Campus-Boulevard 89, Aachen, 52074, Germany

   Jülich Aachen Research Alliance, JARA-Energy, Templergraben 55, Aachen, 52056, Germany

3. Gereon Karsten Stahl Aachen Center for Ageing Chair for Electrochemical Energy Conversion and Storage Systems Institute for Power Electronics and Electrical Drives (ISEA)

   Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Center for Ageing, Reliability and Lifetime Prediction for Electrochemical and Power Electronic Systems (CARL), RWTH Aachen University, Campus-Boulevard 89, Aachen, 52070, Germany

   Chair for Electrochemical Energy Conversion and Storage Systems, Institute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University, Campus-Boulevard 89, Aachen, 52074, Germany

   Jülich Aachen Research Alliance, JARA-Energy, Templergraben 55, Aachen, 52056, Germany

4. Duc Minh Nguyen Aachen Center for Ageing Chair for Electrochemical Energy Conversion and Storage Systems Institute for Power Electronics and Electrical Drives (ISEA)

   Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Center for Ageing, Reliability and Lifetime Prediction for Electrochemical and Power Electronic Systems (CARL), RWTH Aachen University, Campus-Boulevard 89, Aachen, 52070, Germany

   Chair for Electrochemical Energy Conversion and Storage Systems, Institute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University, Campus-Boulevard 89, Aachen, 52074, Germany

   Jülich Aachen Research Alliance, JARA-Energy, Templergraben 55, Aachen, 52056, Germany

5. Tim Falkenstein Aachen Center for Ageing Chair for Electrochemical Energy Conversion and Storage Systems Institute for Power Electronics and Electrical Drives (ISEA)

   Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Center for Ageing, Reliability and Lifetime Prediction for Electrochemical and Power Electronic Systems (CARL), RWTH Aachen University, Campus-Boulevard 89, Aachen, 52070, Germany

   Chair for Electrochemical Energy Conversion and Storage Systems, Institute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University, Campus-Boulevard 89, Aachen, 52074, Germany

   Jülich Aachen Research Alliance, JARA-Energy, Templergraben 55, Aachen, 52056, Germany

6. Dirk Uwe Sauer Aachen Center for Ageing Chair for Electrochemical Energy Conversion and Storage Systems Institute for Power Electronics and Electrical Drives (ISEA)

   Forschungszentrum Jülich · Helmholtz-Institute Münster · Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Center for Ageing, Reliability and Lifetime Prediction for Electrochemical and Power Electronic Systems (CARL), RWTH Aachen University, Campus-Boulevard 89, Aachen, 52070, Germany

   Chair for Electrochemical Energy Conversion and Storage Systems, Institute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University, Campus-Boulevard 89, Aachen, 52074, Germany

   Helmholtz Institute Münster (HI MS), IMD-4, Forschungszentrum Jülich, Jülich, 52425, Germany

   Jülich Aachen Research Alliance, JARA-Energy, Templergraben 55, Aachen, 52056, Germany