Water-based sodium-ion battery electrolyte, preparation method thereof and water-based sodium-ion battery

The invention discloses a water-based sodium-ion battery electrolyte, a water-based sodium-ion battery and a preparation method of the water-based sodium-ion battery. The preparation method comprises the following steps: firstly, weighing soluble sodium salt, adding the soluble sodium salt into deionized water, and heating and stirring until the soluble sodium salt is completely dissolved; secondly, adding the electrolyte additive and the surfactant until the electrolyte additive and the surfactant are completely dissolved; thirdly, adding the prepared electrolyte into a soft package battery consisting of thick-film positive and negative electrode plates prepared by a dry-method thick-film preparation process, so that the first-circle discharge capacity of the soft package battery is 13mAh, the capacity retention ratio is 85% when a sodium manganate and sodium titanium phosphate soft package battery system circulates for the 300th circle, the first coulombic efficiency is 97%, and the second-time coulombic ef