Electrode/electrolyte Interface Modification For Aqueous Zinc-ion Battery

Aqueous zinc-ion batteries have the characteristics of high safety,low cost and high energy density,and show great advantages in the field of large-scale energy storage.However,there are still a series of problems such as dendritic growth,slow corrosion and passivation during the charging and discharging process in the zinc anode.Additionally,Mn-based oxides as the cathode of Zn-ion battery suffer phase transformation and dissolution of manganese.Therefore,improving the electrode/electrolyte interface is of great significance to improve the Zn-ion battery performance.This thesis mainly improves the stability of the electrode/electrol-yte interface by modifying the positive electrode surface and adding different additives to the electrolyte,and then improves the overall performance of the aqueous zinc-ion battery.（1）Micron-sized three-dimensional porous Mn O_xcubes are prepared by hydrothermal method,followed by coating a layer of In₂O₃to obtain three-dimensional porous Mn O_x@In₂O₃cubes.The three-dimensional porous structure is conducive to build a channel for rapid ion transport,and the In₂O₃coating layer is conducive to inhibiting the irreversible phase transition of Mn O_xand the dissolution of manganese during the electrochemical cycling,and stabilizing the electrode/electrolyte interface.The Zn-ion battery using three-dimensional porous Mn O_x@In₂O₃cubes as the positive electrode maintains a high capacity of 260 m Ah g^-1even after 400 cycles of stable cycles at a low current density of 0.3 A g^-1.After 4000 cycles at1.8 A g^-1,t this battery remains 81 m Ah g^-1,and still shows a high reversible capacity of 73.4m Ah g^-1even at a high current density of 6.0 A g^-1.（2）Gelatin as an organic additive is added into the common electrolyte（2MZnSO₄+0.1M Mn SO₄）of zinc-ion batteries to enhance the electrode/electrolyte interface.The amide group in gelatin can be tightly adsorbed on the surface of the negative electrode,prevent the continuous deposition of Zn on the tip owing to steric hindrance,thereby protecting the negative electrode/electrolyte interface of the battery and inhibiting the growth of dendrites.At a current density of 3 m A cm^-2,the Zn|Zn symmetric battery using the electrolyte with 0.5g L^-1gelatin stably cycles for more than 1300 hours.The Zn-Mn O₂batteries using the electrolytes with 0.5 and 1.0 g L^-1gelatin stably cycle for more than 3000 times at a current density of 1.8 A g^-1.However,when the amount of gelatin is larger than 1.0 g L^-1,the deposition of Zn becomes difficult due to the adsorption of gelatin,resulting in a significant decreasing of capacity.（3）Inorganic corrosion inhibitor In₂（SO₄）₃is added into the common electrolyte（2MZnSO₄+0.1M Mn SO₄）to stabilize the Zn electrode interface and improve the electrochemical performance of the Zn-ion battery.The introduction of In³⁺slows down the corrosion of the zinc electrode and inhibits the growth of dendrites.When the current density is 0.5 m A cm^-2,the symmetrical battery with 0.5 g L^-1of In₂（SO₄）₃added into the electrolyte shows excellent cycle performance for up to 1400 hours.The Zn//Mn O_x@In₂O₃full battery has a stable cycle of more than 1000 cycles and a capacity retention rate of more than 85%at0.3 A g^-1.