Influence of position and intensity of production-caused inhomogeneities on the spatially-resolved performance parameters and total performance of lithium-ion cells

• Applicant: Professorin Dr.-Ing. Julia Kowal
• Subject Area: Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 461805740

One way to reduce the cost of lithium-ion batteries (LIB) is to increase the throughput of the production through innovative handling processes. The unavoidable interaction between assemblies and electrodes creates uneven current density distributions in the electrodes and thus influences the performance of the LIB. In addition to defects that have already been investigated, little is known about the effects of production-related loads when handling the electrodes. Especially when designing innovative production lines, it is therefore important to clarify what influence various intensities and positions of inhomogeneities have on the performance of the LIB.The aim of this project is to investigate the (positional) influence of inhomogeneities (defects and loads) on electrodes on the LIB performance. It can be split up into two aims. The first aim is to identify the influence of inhomogeneities on LIB performance with the help of an experimentally supported equivalent circuit model (ESBM) in order to compare the influences of the inhomogeneities for the first time. The second aim is to also determine the influence of the position. For this purpose, an ESBM for spatially resolved characterization (oESBM) is developed and parameterized with the help of an innovative test cell for spatially resolved characterization. For both aims, the defects particle contamination, moisture and pinholes and the mechanical loads compression, tension and bending are examined. The aging mechanisms SEI growth and lithium plating are then forced through calendar and cyclical aging with test cells. The performance analysis focuses on Coulomb's efficiency, impedance and capacitance. The results of both aims are finally linked into an application software to enable an ageing prediction. This enables the evaluation of handling processes in production even before they are implemented.

• DFG Programme: Research Grants