Abstract: The present disclosure relates to a method for treating an electromembrane process aqueous composition comprising sodium and/or potassium sulfate, said process comprising removing water from said electromembrane process aqueous composition under conditions suitable for substantially selectively precipitating sodium and/or potassium sulfate monohydrate.

Abstract: A film of lithium capable for example of providing the anode of a polymer electrolyte battery is produced by laminating a lithium sheet between two working rolls. At the outlet, the film remains attached to one of the two rolls up to a given point of the circumference of the latter where it forms an angle of about 90.degree. with the meeting point between the two rollers. A sufficient tension is thereafter exerted on the film, which in any case is inferior to the limit of elasticity of lithium, by pulling the film in order to detach it from the surface of the roller and usually so that the given point moves into an intermediate position between 90.degree. and the meeting point, for example about 45.degree.. The product obtained may also be used any time there is a need for a film of lithium having a thickness for example between 10 and 100 .mu.m.