Method for recovering lithium and method for processing lithium ion secondary battery

A method for recovering lithium, for recovering lithium from a lithium ion secondary battery, the method comprising:

• thermally treating a lithium ion secondary battery having a residual voltage higher than or equal to 80% of a nominal voltage, to obtain a thermally treated product;
• pulverizing the thermally treated product, to obtain a pulverized product;
• and
• recovering lithium from the pulverized product;
• wherein
• the thermally treating comprises:
• heating the lithium ion secondary battery to 350° C. or higher and 430° C. or lower while being placed in a storing container,
• igniting the lithium ion secondary battery during a first stage of heat supply in which a first amount of heat is supplied to the lithium ion secondary battery, and
• once the lithium ion secondary battery ignites, starting a second stage of heat supply that supplies a second amount of heat to the lithium ion secondary battery, the second amount of heat being at a level that is less than or equal to 50% of the first amount of heat;
• wherein
• the storage container has an opening and an openable and closable lid, where a total area of the opening is less than or equal to 12.5% of the total surface area of the storing container with the proviso that the opening is sized to allow a hypoxic atmosphere to form in the storage container during the thermally treating.