LAUSR

Abstract Aging of lithium-ion pouch cells causes significant cell thickness growth and can consequently lead to high loads onto the cell stack and module frame in automotive application. In order to investigate force evolution and its interaction with aging, cells must be cycled under mechanically representative bracing conditions. Known test setups for single-cell testing from literature fail to meet important requirements. A realistic module stiffness must be simulated by highly plane parallel plates to achieve a homogeneous load onto the cell. The cell shall be sufficiently and homogeneously cooled. Additionally, the realistic bracing procedure as in industrial assembly and simultaneous measurements of cell displacement and force must be conducted. This paper presents the design and validation of a pneumatic cell press which meets all of the above requirements and is able to universally simulate the stress-strain characteristics of any module by feedback control. The homogeneity requirements were scrutinized by two-dimensional temperature and pressure measurements. Small deformations of the setup under loads of up to 45 kN are measured and corrected for. Several cycles of an automotive cell under constant force and module stiffness simulation of 300 kN mm−1 show strong nonlinear initial and subsequent continual linear cell thickness growth.