Ultra-low-Dosage Lignin-Derived PHU-Enhanced PVDF Binders for High-Performance Lithium Metal Batteries

Lithium metal batteries (LMBs) have emerged as a pivotal next-generation energy storage technology due to their exceptional theoretical energy density. Their development faces fundamental challenges from conventional poly(vinylidene fluoride) (PVDF) binders, including high crystallinity, insufficient adhesion, and poor interfacial compatibility with electrode active materials. In this work, we developed a convenient one-pot strategy to enhance the performance of the traditional PVDF binder by using lignin-derived polyhydroxyurethane (PHU). The ultra-low-dosage (1 wt %) lignin-derived PHU-modified PVDF binder (LP1) effectively enhanced the flexible amorphous domains and interfacial adhesion, leading to significantly improved Li+ transport and cyclic stability. The electrode with LP1 binder exhibited a substantially higher Li+ diffusion coefficient of 3.47 × 10–14 cm2 s–1 than that of the PVDF binder (2.05 × 10–15 cm2 s–1). The LP1-based battery demonstrated a capacity retention of 93.8% after 400 cycles at 1C compared to the 82.5% of the PVDF-based battery. This work not only establishes a foundation for the application of lignin-derived binders but also provides important guidance for binder design toward next-generation binder systems in advanced LMBs.