Self-Healable and Degradable Polycaprolactone-Based Polymeric Binders for Lithium-Ion Batteries

Abstract

Self-healing polymers can repair damage caused by external stimuli or cracks, making them ideal for enhancing material stability. However, the utilization of nonbiodegradable materials in many of these polymers raises significant environmental concerns. To address this issue, our study focuses on the development of self-healing, degradable polymers using polycaprolactone (PCL). Biodegradable polymers, such as PCL, have emerged as potential candidates for reducing plastic waste and mitigating environmental pollution. In this work, we synthesized three amine-terminated PCLs through a three-step process and subsequently reacted them with isophorone diisocyanate to produce urea-linked PCLs (PCLn-IUs). We examined the self-healing ability of PCLn-IUs and observed an increase in the self-healing capability with higher urea bond contents. Furthermore, we investigated the potential of employing PCLn-IUs as a replacement binder for graphite anodes in lieu of the conventional nonbiodegradable binder in lithium-ion batteries (LIBs), aiming to leverage the advantage of self-healing properties in binder materials. Remarkably, electrodes based on PCL12-IU demonstrated exceptional performance at high C-rates, achieving 90% capacity retention at 2C vs. 0.5C. Our findings underscore the significant potential of self-healing and biodegradable PCLn-IUs as binders for LIBs, highlighting their suitability for addressing environmental concerns in battery technology.