Comprehensive Analysis of Float Current Behavior and Calendar Aging Mechanisms in Lithium‐Ion Batteries

Batteries & Supercaps, vol. 9

Abstract

Aiming to quantify degradation currents from solid electrolyte interphase formation () and gain of active lithium due to cathode lithiation (), resulting from electrolyte decomposition, the float current behavior of lithium‐ion batteries is investigated with different cathode materials. The float current, , represents the recharge current required to maintain the cell at a fixed potential during calendar aging. This current arises as lithium is irreversibly consumed at the anode or inserted into the cathode, shifting the electrode potentials. To account for the asymmetric response of the electrodes, a voltage‐dependent scaling factor, , is introduced, derived from the slopes of the electrode‐specific voltage curves. Using this factor in combination with measured float currents and capacity loss rates from check‐up tests, and is quantified at 30 °C across various float voltages. Although the and capacity data are limited to 30 °C, the model is extended to a range of 5–50 °C using only float current measurements. The results show that using capacity loss rates alone underestimate and that , contributes significantly to the observed float current at elevated voltages, indicating that cathode lithiation plays an increasingly important role in high‐voltage calendar aging.

Authors 4

1. Mohamed Azzam corresponding Aachen Chair for Electrochemical Energy Conversion and Storage Systems Institute for Power Electronics and Electrical Drives (ISEA) Chair for Electrochemical Energy Conversion and Storage Systems Institute for Power Electronics and Electrical Drives (ISEA)

   Technische Hochschule Ingolstadt · RWTH Aachen University

   Affiliation as printed

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

   Research Group Electromobility and Learning Systems Technische Hochschule Ingolstadt D‐85049 Ingolstadt Germany

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

   Research Group Electromobility and Learning Systems, Technische Hochschule Ingolstadt, D-85049 Ingolstadt, Germany

2. Dirk Uwe Sauer Aachen Chair for Electrochemical Energy Conversion and Storage Systems Institute for Power Electronics and Electrical Drives (ISEA) Institute for Power Generation and Storage Systems (PGS) E.ON ERC Chair for Electrochemical Energy Conversion and Storage Systems Institute for Power Electronics and Electrical Drives (ISEA) Institute for Power Generation and Storage Systems (PGS)

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

   Affiliation as printed

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

   Helmholtz Institute Münster (HI MS), IEK 12 Forschungszentrum Jülich 52425 Jülich Germany

   Institute for Power Generation and Storage Systems (PGS) E.ON ERC RWTH Aachen University Mathieustrasse 10 52074 Aachen Germany

   Jülich Aachen Research Alliance JARA‐Energy Templergraben 55 52056 Aachen Germany

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

   Institute for Power Generation and Storage Systems (PGS), E.ON ERC, RWTH Aachen University, Mathieustrasse 10, 52074 Aachen, Germany

3. Christian Endisch

   Technische Hochschule Ingolstadt

   Affiliation as printed

   Research Group Electromobility and Learning Systems Technische Hochschule Ingolstadt D‐85049 Ingolstadt Germany

   Research Group Electromobility and Learning Systems, Technische Hochschule Ingolstadt, D-85049 Ingolstadt, Germany

4. Meinert Lewerenz

   Technische Hochschule Ingolstadt

   Affiliation as printed

   Research Group Electromobility and Learning Systems Technische Hochschule Ingolstadt D‐85049 Ingolstadt Germany

   Research Group Electromobility and Learning Systems, Technische Hochschule Ingolstadt, D-85049 Ingolstadt, Germany