Real time characterization of the current collector's role on the electro-chemo-mechanical coupling performance of Si composite electrode

Abstract

The electro-chemo-mechanical properties of the electrode play an essential role in the lifetime and performance of lithium-ion batteries (LIBs). Large diffusion-induced stress causes degradation of mechanical properties, resulting in the fading of capacity and cycle performance. Current collector, an important component of the batteries, acts as a crucial part to the structural stability and mechanical integrity of the electrode. In this paper, the effect of current collector's thickness on the cyclic performance of silicon (Si) composite electrodes is investigated experimentally. The results demonstrate that a thicker current collector can hugely enhance the cyclic performance of Si composite electrodes. Besides, an in-situ measurement is conducted to analyze the relationship between mechanical response and cycle performance. A cantilever model is employed to extract the stress evolution within the Si composite electrode with different current collectors. Obviously, the thicker collector has strong restrictions on the electrode bending caused by the volume expansion of silicon particles, thus induce larger compressive stress. This can help maintain the structural stability of the composite electrodes and further enhance the mechanical performance and electrochemical performance of the Si based electrodes.