Advancing aqueous zinc-ion battery performance with pullulan through preferential adsorption on zinc anode surfaces and enhanced zinc ion desolvation
Aqueous zinc-ion batteries (AZIBs) have emerged as a prominent contender in energy storage devices, largely due to their substantial theoretical capacity, and competitive cost. Nevertheless, the uncontrollable proliferation of zinc dendrites and the emergence of parasitic side effects present a significant challenge to the practical implementation of AZIBs. Herein, a novel low-cost and environmentally friendly electrolyte additive, pullulan polysaccharide (PLL), was incorporated into a common ZnSO 4 electrolyte to stabilize the Zn anode of high-performance AZIBs. Experimental and theoretical calculations demonstrated that PLL can modulate the interaction of Zn 2+ with H 2 O molecules, reducing the number of H 2 O molecules around Zn 2+ and thereby facilitating the desolvation of Zn 2+ . Furthermore, the PLL molecules adsorbed on the surface of the zinc anode formed a protective layer that permitted the uniform deposition of Zn 2+ . As anticipated, the cycle life of the Zn//Cu asymmetric cells using 2M ZnSO 4 + 1 wt% PLL as the electrolyte exceeded 3700 cycles, with a high average Coulombic Efficiency of 99 %. The Zn//Zn symmetric cell with PLL as the electrolyte exhibited excellent cycling stability, demonstrating prolonged operational longevity that exceeded 1200 h. Furthermore, full cells with PLL additive displayed enhanced long-term durability when coupled with sodium vanadate (NVO) cathode.
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