Exploring the feasibility of sodium alginate as a binder in aqueous zinc-ion batteries incorporating α-MnO2 nanorod cathodes

Batteries with good stability and capacity are required to maximize the role of electrical energy storage. The use of a binder is essential for maintaining the structural integrity of the electrodes and optimizing battery performance. Polyvinylidene fluoride (PVDF) has been a commonly used binder; however, its high toxicity and the expensive solvent (N-methyl-2 pyrrolidone) used in its processing pose concerns. In this study, we show that as an alternative to replace PVDF, to some extent, sodium alginate (SA) demonstrates better electrochemical performance owing to its cross-linking with Zn2+ ions, which maintains the stability of the a-MnO2 electrode in zinc-ion batteries (ZIBs). The strong and reversible chemical bonding of the binder with the active material causes the binder to fill the cracks occurring during electrochemical cycling and self-repairing these cracks upon cycling. After prolonged cycling, the electrode with SA as the binder exhibited better stability than that with PVDF. Furthermore, the rate capability test also suggested that the electrode with the SA binder recovered well after cycling at high current rates. This study highlights the potential of SA as an alternative, self-healing, and environmentally friendly binder for aqueous ZIB applications, thereby opening avenues for maximizing its usage in energy-storage systems.