Hydroxyl-rich multifunctional polysaccharide electrolyte additive for highly reversible aqueous zinc-ion batteries

Aqueous zinc-ion batteries have emerged as highly promising energy storage devices due to their high theoretical capacity, low cost, and high safety. However, they still suffer from dendrite growth and parasitic side reactions caused by reactive aqueous electrolytes, which not only compromise reversibility but may also lead to internal short circuits, severely limiting practical applications. Herein, inulin (INU), a hydroxyl-rich polysaccharide, is proposed as a multifunctional electrolyte additive. Experimental and density functional theory calculations reveal that INU molecules effectively disrupt the original hydrogen-bond network, facilitating Zn2+ desolvation and rapid migration, thereby effectively resisting hydrogen evolution reaction, Zn corrosion, and by-products formation. Additionally, INU preferentially adsorbs on the Zn(002) crystal plane, forming a hydrophobic protective layer and guiding uniform Zn2+ deposition, thus inhibiting random dendritic growth. The presence of INU also effectively retards the dissolution process of V2O5. As a result, the Zn||Zn symmetric cell assembled with INU-3 electrolyte achieves an extended cycling life of 2400 h at a current density of 0.5 mA cm−2 and an areal capacity of 0.5 mAh cm−2. Furthermore, the Zn||V2O5 full cell exhibits a high capacity of 386.0 mAh g−1 at 0.5 A g−1 and a high capacity retention of 55.26% at 8 A g−1. The full cell maintains remarkable capacity retention of 73% after 500 cycles at 1 A g−1 and 91% after 1000 cycles at 3 A g−1. This work inspires the study of electrolyte additives for aqueous zinc-ion batteries.