State of the Art of Lithium-Ion Pouch Cells in Automotive Applications: Cell Teardown and Characterization

Abstract

A large-format pouch cell with a nominal capacity of 78 Ah from the Volkswagen ID.3 was disassembled and analyzed to characterize the state of the art of industrial-scale cells in automotive applications. The cell components were separated from each other, geometrically measured, and weighed to quantify the volume and weight fractions from electrode to cell level. Material samples from the electrodes were characterized by scanning electron microscopy (SEM), elemental analysis, and mercury porosimetry. Half cells were built post mortem and assessed in electrochemical tests. The results revealed a stacked cell of laminated electrode layers. The cathode showed a bi-modal particle distribution and its active material ranged with LiNi0.65Mn0.2Co0.15O2 in between NMC622 and NMC811. Silicon-free graphite was used as the anode active material. Over 75% of the cell mass and over 81% of the cell volume directly contribute with its active material to the specific energy of 268 Wh kg−1 and energy density of 674 Wh L−1 at cell level. 91% of the anode and 93% of the cathode were utilized in the pristine cell, respectively. In charge rate tests, the anode was identified as the limiting electrode. The results provide valuable insights into the state of the art of automotive lithium-ion batteries and serve as a reference for scientific research.