Green power unleashed: Plant extracts forge oxygen bridges for achieving zinc-ion battery super-longevity

Abstract

The reversibility and cycling stability of aqueous zinc-ion batteries (AZIBs) are largely limited by serious parasitic reactions and uncontrolled dendrites growth. Herein, caulis polygoni multiflori extract (CPM) has been proposed as electrolyte additive to build a convenient bridge to clear the way for Zn2+ to migrate to the zinc plate. CPM can set up "oxygen bridges" between Zn plate and Zn2+ to capture Zn2+ through O and Zn2+ coordination, effectively tuning the Zn2+ coordination environment, reducing the activity of H2O molecules to further suppress H2O-induced side reactions and protecting Zn anode from corrosion. As an ion accelerator, the CPM can not only adsorb on the anode surface to control the random diffusion of Zn2+ and induce uniform Zn2+ deposition, but also adsorb on the cathode surface to adjust an invertible MnO2/Mn2+ manganese deposition/dissolution reaction by facilitating the intercalation/dissolution processes of Zn2+ and preventing the generation of irreversible MnOOH. Consequently, the corrosion inhibition efficiency of the Zn is up to 97.2% at a CPM addition of 500 mg L−1, and the symmetric cell life is stable for 2900 h at 2 mA cm−2 and 2 mAh cm−2. The Zn||MnO2 battery with CPM achieves a higher specific capacity and capacity retention after 1000 cycles. This work provides a new pathway for the development of green and efficient electrolyte additives to accomplish a highly reversible AZIBs.