NOVELTY - A mercury-free alkali button battery with positive pole conducting film comprises negative pole cover, negative pole calamine cream, positive piece and positive pole shell.    USE - The mercury-free alkali button battery with positive pole conducting film is useful for industrial applications.    ADVANTAGE - The mercury-free alkali button battery with positive pole conducting film has a conducting film which isolates oxidizing function of manganese dioxide for positive pole shell to reduce gas, prolong service life of battery, and improve battery storage performance. Metal negative cover is plated with an indium tin alloy layer to isolate the contact of battery negative pole calamine cream and negative pole cover; so it does not need to add mercury which prevents gas from expanding to reach mercury-free environment protection demand.    DETAILED DESCRIPTION - A mercury-free alkali button battery with positive pole conducting film comprises negative pole cover, negative pole calamine cream, positive piece and positive pole shell; membrane is set between negative pole cover and positive pole cover and has sealing cushion rubber to make negative pole cover and positive pole cover interference cooperate; positive pole shell closing opening seals edge side; inner surface of button battery metal negative pole cover (1) is plated with an indium tin alloy layer (2); negative pole calamine cream (3) composed of zinc powder, metal indium, bismuth and aluminum powder mixing uniformly is set between negative pole cover (1) and membrane (5); inner surface of positive shell (8) is coated with a conducting film (7); positive piece (6) is set between conducting film (7) and membrane (8). An INDEPENDENT CLAIM is included for the preparation method of positive pole conducting film of mercury-free alkali button battery with positive pole conducting film comprises (1) making metal steel band punch to positive pole shell (8), removing dirt, and grease; (2) inner surface of positive pole shell (8) is electrically plated with metal nickel layer; (3) preparing conducting film slurry; (4) carrying out conducting film slurry filtering on the same production line, ejecting conducting film slurry by pump, coating a conducting film on surface of electric plated metal nickel layer in positive pole shell, drying at 90 degrees C and packing finished product; where conducting film (7) comprises conducting carbon: 30-50 pts.wt. of graphite; adhesive: 5-20 pts.wt. of polyvinyl-butyral; solvent: 40-60 pts.wt. of methyl ethyl ketone or isobutanol; copper (Cu) is not greater than 0.0002%; molybdenum (Mo) is not greater than 0.0002%.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of a mercury-free alkali button battery with positive pole conducting film.    Button battery metal negative pole cover (1)    Indium tin alloy layer (2)    Negative pole calamine cream (3)    Membrane (5)    Positive piece (6)    Conducting film (7)    Inner surface of positive shell (8)