Comparative Study of Binder Stability for Aqueous Lithium-Ion and Solid-Boosted Flow Batteries

The replacement of polyvinylidene fluoride (PVDF) with environmentally friendly binders offers potential advantages in the development of aqueous lithium-ion batteries (ALIBs) and flow batteries (FBs) incorporating solid charge carriers (so-called solid boosters). This study investigates the electrochemical stability of ethyl cellulose and cross-linked gluten as substitutes for PVDF in LiMn₂O₄ (LMO) cathodes for aqueous Li-ion battery electrodes and solid boosters for FBs. The millimetre-scaled solid booster beads must be easily produced on a large scale, and at the same time, their charging and discharging must be reversible over long durations under electrolyte tank conditions. The binders were tested under standardized conditions for discharge capacity and cycling stability. Our results demonstrate that ethyl cellulose and cross-linked gluten can rival the electrochemical stability of PVDF, maintaining initial discharge capacities near 100 mAh g⁻¹ at 0.2C for LMO cathodes and exhibiting reasonable capacity retention over hundreds of cycles. This work supports the feasibility of sustainable electrode processing, provides promising directions for scalable, eco-friendly electrode fabrication methods, and highlights promising binder candidates for use in aqueous energy storage systems.