The effect of electrode layer quantity on the electrochemical performance and swelling behavior of pouch cells

With the development of electrochemical energy storage, in recent years, the capacity of commercial batteries has shown a gradually increasing trend. Coin batteries differ from commercial pouch batteries in terms of electrochemical performance and service life, and the test results are difficult to be transferred to practical applications; pouch batteries, due to the ability to provide conditions more similar to industrial applications and the need for less consumables, have become the preferred testing medium. However, the specifications of the pouch batteries still have an impact on performance, resulting in deviations in the reliability of the test results. Therefore, we investigated the evolution laws of electrochemical-mechanical properties of pouch batteries with different electrode layers. Specifically, we revealed the influence of the outermost graphite coating of the battery on its electrochemical performance through pouch batteries with different electrode layers. The fewer the number of layers, the more obvious the initial Coulomb efficiency reduction and cycle capacity loss caused by the outermost anode coating. These effects were verified by complementary X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Furthermore, the results of the stress test indicate that the layer-normalized reversible swelling force of cells at different layers decreases linearly with capacity loss and the slope remains consistent, which provides a reliable indicator for battery aging assessment.