Method for manufacturing a steel strip or sheet for a battery case and battery case made therefrom

A method for manufacturing a steel strip for a battery case, wherein the method comprises:

• providing a Ni-plated steel strip, and
• applying a graphene coating on one or both sides of the Ni-plated steel strip by a continuous roll-to-roll process, wherein the continuous roll-to-roll process is operated fully continuously by joining a leading edge of a coil of Ni-plated steel strip to a trailing edge of the preceding coil of Ni-plated steel strip in a joining section before entering the step of fast heating of the Ni-plated steel strip and separating the Ni-plated steel strip after cooling the graphene coated Ni-plated steel strip to produce coils of graphene coated Ni-plated steel strips, comprising the following consecutive steps:
• fast heating at a heating rate of at least 50° C./s, of the Ni-plated steel strip in an inert, non-oxidising or reducing atmosphere in a heating section to a heat soak temperature of between 400 to 850° C.;
• holding the Ni-plated steel strip in the heat soak section at the heat soak temperature;
• projecting an inert, non-oxidising or reducing gas carrier comprising a graphene precursor on the heated Ni-plated steel strip in the heat soak section to produce an adhering graphene coating layer on the Ni-plated steel strip wherein the deposition growth time for the graphene coating layer is in the range of 0.10 seconds to 60 seconds;
• cooling the graphene coated Ni-plated steel strip in a cooling section wherein the cooling medium is inert or reducing with respect to graphene;
• post-processing the graphene coated Ni-plated steel strip.