An object of the present invention is to provide a phycocyanin pigment composition insoluble in water and provide food, cosmetics, a coating material or a printing marker for pharmaceuticals or agricultural chemicals, a stationery product, a writing tool, a printing ink, an inkjet ink, a metal ink, a paint, a plastic coloring agent, a color toner, a fluorescent labeling agent, a fluorescent probe, or a chemical sensor, each containing the pigment composition. It was found that the phycocyanin pigment composition containing phycocyanin and a metal or a metal compound was insoluble in water, and thus the present invention was accomplished.

An object of the present invention is to provide a phycocyanin pigment composition insoluble in water and provide food, cosmetics, a coating material or a printing marker for pharmaceuticals or agricultural chemicals, a stationery product, a writing tool, a printing ink, an inkjet ink, a metal ink, a paint, a plastic coloring agent, a color toner, a fluorescent labeling agent, a fluorescent probe, or a chemical sensor, each containing the pigment composition. It was found that the phycocyanin pigment composition containing phycocyanin and a metal or a metal compound was insoluble in water, and thus the present invention was accomplished.

A method for producing lithiated pyomelanin (LPM), sodiated pyomelanin (SPM) and potassiated pyomelanin (PPM) is provided. A method is also provided for improving the safety of lithium-ion (Li-ion), sodium-ion (Na-ion) and potassium-ion (K-ion) batteries. The method employs using LPM, SPM or PPM in the negative compartment (anode) of the batteries. These LPM Li-ion, SPM Na-ion and PPM K-ion batteries have decreased tendencies to overheat and/or explode.