Case for secondary battery and method of manufacturing case

1. A case for a secondary battery, the case comprising:

a body configured to accommodate an electrode assembly and composed of a conductive material;

an oxide film on the body, the oxide film being on two oppositely facing-away surfaces of the body; and

a colored sealing layer on the oxide film, the colored sealing layer comprising a dye to provide the color of the colored sealing layer,

wherein the colored sealing layer is on two oppositely facing-away surfaces of the body,

wherein the colored sealing layer is composed of organic materials having a plurality of colors to provide the colored sealing layer with the plurality of colors or a plurality of patterns,

wherein:

the body comprises an aluminum plate composed of aluminum or an aluminum alloy, and

the oxide film is an aluminum oxide film formed on the aluminum plate by electrochemically treating the aluminum plate in a state where the aluminum plate is immersed in an adipic acid solution,

wherein the electrochemical treatment in the adipic acid solution is performed in which:

molarity of the adipic acid solution is in a range from about 0.5 M to about 1.5 M;

processing temperature is in a range from about 60° C. to about 80° C.; and

processing voltage is in a range from about 100 V to about 150 V

wherein the aluminum plate is mechanically hardened by thickening the aluminum oxide film with an electrochemical treatment in a boric acid solution

wherein the electrochemical treatment in the boric acid solution is performed in which:

molarity of the boric acid solution is in a range from about 0.5 M to about 2.0 M;

processing temperature is in a range from about 60° C. to about 80° C.; and

processing voltage is in a range from about 250 V to about 500 V,

wherein the oxide film is configured to increase mechanical Vickers hardness of the case, and the colored sealing layer is configured to fill pores of the oxide film,

wherein the Vickers hardness of the case is configured to be from about 350 Hv to about 450 Hv.

2. A vehicle comprising a battery comprising the case of claim 1 , wherein the vehicle is selected from the group consisting of internal combustion engine vehicles, hybrid electric vehicles, and electric vehicles.

3. The case of claim 1 , wherein the body with the oxide film and the colored sealing layer is configured to accommodate a hybrid electric vehicle or an electric vehicle.

4. The case of claim 1 , further comprising another oxide film formed between the oxide film and the colored sealing layer.