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Electrochromic materials are able to change the optical properties persistently and reversibly by an extemal voltage [1].NiO is one of the most well-known electrochromicmaterial because of its high optical modulation, fast switchingbetween colored and bleached states, good cyclic reversibility,memory effect and low cost[2].Normally, the approaches for producing electrochromic NiO films include sputtering [3], electrodeposition [4], chemical bath deposition(CBD) [5], spray pyrolysis [6].Among these techniques, the sol-gel process is low-cost and can be used to prepare large area films.It is easy to add different material components using the sol-gel technique and it has a low thermal budget in layer or device production[7].In addition, the sol-gel process offers good approaches to the synthesis of oxide materials.Starting from molecular precursors, an oxide network is obtained via inorganic polymerization reactions.These reactions mainly occur in solutions and the term "sol-gel processing" is often broadly used to describe the synthesis of inorganic oxides by wet chemical methods[8].We report on NiO films synthesized by sol-gel method.Depending on different annealing temperatures, the structural, morphological, optical and electrochemical properties of NiO films have been investigated in detail.Amorphous NiO films annealed at lowerannealedtemperature have higher electrochromic activity as well as poor reversibility.The lower crystallinity film exhibits a noticeable electrochromic performance, such as the highest optical modulation, cycling durability, relatively fastelectrochromic response time.All these analyses provide an excellent methodof sol-gel for preparing the electrochromic NiO film in a low-cost way.