A method of manufacturing lithium or lithium alloy anodes for electrochemical cells by an extrusion process wherein a lithium or lithium alloy ingot is formed into a thin sheet. The method is adapted to extrude thin sheet having a width exceeding the diameter of the lithium or lithium alloy ingot and enables the extrusion of lithium or lithium alloy thin sheets with more than one lithium or lithium alloy ingot. The invention also provides a die assembly adapted to allow adjustment and fine tuning of a die aperture while the extrusion process of a lithium or lithium alloy ingot is being carried out.