The printed electronics technology can be used to efficiently construct smart devices and is dependent on functional inks containing well-dispersed active materials. Two-dimensional (2D) materials are promising functional ink candidates due to their superior properties. However, the majority 2D materials can disperse well only in organic solvents or in surfactant-assisted water solutions, which limits their applications. Herein, we report a lithium (Li)- ion exchange method to improve the dispersity of the Na₂W₄O₁₃ nanosheets in pure water. The Li-ionexchanged Na₂W₄O₁₃ (Li_xNa_{2 – x}W₄O₁₃) nanosheets show highly stable dispersity in water with a zeta potential of – 55 mV. Moreover, this aqueous ink can be sprayed on various substrates to obtain a uniform Li_xNa_{2 – x}W₄O₁₃ nanosheet film, exhibiting an excellent electrochromic performance. A complementary electrochromic device containing aLi_xNa_{2 – x}W₄O₁₃ nanosheet film as an electrochromic layer and Prussian white (PW) as an ion storage layer exhibits a large optical modulation of 75% at 700 nm, a fast switching response of less than 2 s, and outstanding cyclic stability. ThisNa₂W₄O₁₃-based aqueous ink exhibits considerable potential for fabricating large-scale and flexible electrochromic devices, which would meet the practical application requirements.