▎ 摘　　要

NOVELTY - Method for preparing fluorine-free MXene by electrochemical etching method involves (a) taking two MAXs as a working electrode and a counter electrode, soaking in a mixed aqueous solution of hydroxide and chloride, applying voltage, and stirring, (b) collecting black precipitate in the solution by centrifugal washing, ultrasonically processing under the protection condition of ice water bath and inert gas, (c) centrifuging and washing for multiple times until the upper layer liquid is black, and (d) freezing and drying the black layer liquid to obtain at least one layer or a single layer MXene. The MAX is titanium-aluminum carbide, vanadium-aluminum carbide and/or molybdenum-aluminum carbide. The hydroxide is lithium hydroxide, sodium hydroxide or potassium hydroxide. The chloride is lithium chloride, sodium chloride or potassium chloride. USE - Method useful for preparing fluorine-free MXene such as graphene-like structure of twodimensional transition metal carbide by electrochemical etching method, useful in electrochemical energy storage, electromagnetic shielding, and sensor. ADVANTAGE - The method provides fluoride-free MXene by using electrochemical etching method without using fluorine-containing reagent, organic solvent and organic intercalating agent. The etching process is carried out at room temperature, and the etching time is short. The obtained MXene and nano-cellulose and carbon nano-fiber filtering film, and the specific capacitance is 249.9 F/g. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for an assembly method of super capacitor.