Dual-Modified Thermoset Polyurethane Particles as Active Organic Additives in Electrolytes for High-Performance Flexible Zinc–Air Batteries

The rapid accumulation of thermoset flexible polyurethane (TFPU) foams poses a serious challenge to the environment and human health, necessitating innovative recycling methods. Herein, an active organic additive for gel polymer electrolytes (GPEs) was designed and synthesized by grafting flexible polyurethane (PU) chains and depositing polydopamine (PDA) onto the surface of regenerated thermoset flexible PU particles (PUP), which significantly optimized the GPEs and achieved value-added recycling of thermoset flexible PU foams. Benefiting from the rigid–flexible bifunctional structure and abundant zinc-philic polar groups of the PDA@PU@PUP, the mechanical properties and ionic conductivity of the poly(vinyl alcohol) (PVA)-based GPEs were successfully balanced. The assembled flexible zinc–air batteries (FZABs) exhibited higher power density and longer room-temperature cycle life compared with pure PVA-based FZAB. Failure analysis showed that the introduction of the composite-modified PUP into the PVA matrix contributed to the redistribution of Zn2+ flux and the modulation of zinc ion solvation structure, which achieved uniform deposition of zinc and effective inhibition of side reactions. To the best of our knowledge, this is the first report on the introduction of active organic additives in PVA-based GPEs. Furthermore, this study provides an approach for sustainable recycling of thermoset flexible PU foams and an effective strategy for electrolyte optimization in advanced energy storage applications.