Production of metal-based thin foils

Abstract

A method for producing metal-based thin foils is provided, which includes the steps of extruding a metal through an extruder to form a preliminary foil, cooling the preliminary foil in a coolant bath, and rolling the preliminary foil in a rolling system containing at least two rollers to form a metal-based thin foil.

Claims

1. A process for the production of thin metal-based foils, comprising the acts of: providing an extruder, a coolant bath, and a rolling system comprising at least two rollers; extruding a metal through the extruder to form a preliminary foil, wherein the preliminary foil has a thickness from 100 to 150 m; cooling the preliminary foil in the coolant bath containing liquid nitrogen at a temperature between 63 K and 77 K; and then rolling the preliminary foil at least once in the rolling system comprising at least two rollers to form a thin metal-based foil with a thickness from 5 to 80 m, wherein during rolling, the preliminary foil is kept below its tear threshold by increasing the temperature of the center of the foil, wherein the rolling system is cooled by the same coolant used in the coolant bath, and wherein the rolling system is not immersed in the coolant bath.

2. The process according to claim 1, wherein the thin metal-based foil is a foil selected from the group consisting of an alkali metal, an alkaline earth metal, an alloy of alkali metal and an alloy of alkaline earth metal.

3. The process according to claim 2, wherein the thin metal-based foil is a lithium-based foil.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 is a diagram of a process for the rolling of an ultra-thin lithium foil.

DETAILED DESCRIPTION

(2) FIG. 1 shows a lithium ingot (1), which is extruded in a heated extruder (2). A preliminary foil (3) is thus obtained with thickness from 100 to 150 m. This preliminary foil can be directly the extrudate of the extruder, or the extrudate of the extruder can be subjected to a preliminary rolling process for initial thickness reduction in order to achieve the thickness mentioned. The aim is to obtain, from the preliminary foil, an ultra-thin foil with final thickness from 5 to 80 m. For this purpose, the preliminary foil is passed by means of rollers through a bath (4) with liquid nitrogen at a temperature of 77 K. The preliminary foil is then fed into a roll system (5) for rolling under the pressure exerted by the rollers to form a thin foil (6). The roll pressure and the roll speed here are selected in a manner such that the pressure exerted by the rolls at all times during rolling is not sufficiently high to break the cold foil. It is moreover necessary that at all times during rolling the foil is kept below its tear threshold by increasing the temperature of the center of the lithium foil during rolling and by controlling the pressure exerted by the rolls. The pressures that can be applied to the cold foil, or to the foil with temperature slowly increasing again in its center, are however sufficiently high to obtain a thin foil (6) with final thickness from 5 to 80 m which has not broken and has not torn, and which can be wound by a winder (7). The precise pressures and roll speeds that can be applied must be determined empirically on the basis of the rolls used and their radii and surfaces.

(3) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.