Enhancing Heat Dissipation Through Binders by Percolation

In this study, we explore a novel approach to enhance thermal management in Lithium-ion batteries (LIBs) by modifying binder additives. In LIBs, the binder constitutes only 2–5% of an electrode’s mass yet plays a vital role in battery performance. Poly(vinylidene difluoride) (PVDF) is commonly used for its stability, binding ability, and electrolyte absorption. However, as an insulator, PVDF requires conductive additives, such as carbon black, to create electron pathways. Carbon black increases electrical conductivity but has a low thermal conductivity (0.1–0.5 W/m-K), which limits heat dissipation. While other studies have used graphene-based additives to improve thermal conductivity, such approaches face challenges with cost and fabrication complexity. In this study, we introduce indium powder, a metal additive with superior thermal (86 W/m-K) and electrical conductivity (1.2x10^7 S/m), as a scalable and efficient alternative to carbon black. Additionally, by applying a hot press, we reduce the interfacial thermal resistance between indium particles to induce percolation. In this work, we prepare a series of PVDF samples mixed with indium particles and carbon black with varying concentrations. We then annealed the samples by hot-pressing. We then measure the thickness of the samples by scanning electron microscopy (SEM), electrical conductivity by the four-point method, and thermal conductivity by time-domain thermoreflectance (TDTR). We find that carbon black increases electrical conductivity and show a rapid rise at the percolation threshold, but it has a minimal effect on thermal conductivity. In contrast, indium significantly enhances both thermal and electrical conductivity. It achieves up to 3–4 times greater thermal conductivity compared to carbon black. This study demonstrates that indium offers a viable and effective option for binder additives, supporting both heat dissipation and electrical performance, thus paving the way for more efficient and longer-lasting LIBs.