Abstract: A method for selectively removing Li from an input material comprising Li and one or more transition metals, comprising the steps of: contacting said input material with a leaching medium comprising formic acid; and leaching Li from the input material to form a leachate; wherein the concentration of formic acid in the leaching medium is at least 70 wt. %.

Abstract: A method is described for recycling nickel from waste battery material. The method includes providing waste battery material comprising a nickel-containing oxide, reducing the nickel in the waste battery material to the zero oxidation state to provide a reduced waste battery material, reacting the reduced waste battery material with carbon monoxide to form Ni(CO)4, and reacting the Ni(CO)4 with a source of sulfate to form NiSO4. The NiSO4 product is useful as a nickel feedstock in various processes which require a nickel source, including processes which prepare new battery materials.