The Polymer Society of Korea

Abstract

One effective strategy for increasing energy density in lithium-ion batteries is to employ high-specific-capacity active materials. In this regard, silicon-based materials (e.g., Si, SiO_x, and Si/C), which offer substantially higher specific capacity than conventional graphite, are promising candidates for high-energy-density cell design. However, the severe volume change of Si-based active materials during lithiation/delithiation induces mechanical degradation in the electrode, including crack formation and interfacial delamination, which critically undermines long-term cycling stability.
Increasing stack pressure can suppress microstructural evolution in the electrode and effectively mitigate such mechanical degradation. Nevertheless, excessively high operating pressure, on the order of several hundred kPa, may cause plastic deformation of polymeric separators, leading to pore clogging and consequently severe limitations in ionic transport.
In this study, we systematically investigate the correlation between the electrochemical behavior of SiO_x electrodes and the mechanical deformation of polyethylene separators as a function of operating pressure. Based on this coupled electrochemical–mechanical analysis, we propose an optimal pressure window for the stable operation of high-energy-density silicon-based electrodes.