| abstract |
An object of the present invention is to provide a novel sulfur-based positive electrode active material that can greatly improve the cycle capability of a lithium ion secondary battery, a positive electrode including the positive electrode active material, and a lithium ion secondary battery including the positive electrode. The sulfur-based positive electrode active material includes: a carbon skeleton, a polymer derived from a monomer unit having at least one hetero atom-containing portion; and sulfur, when the carbon skeleton is formed from the polymer by heat treatment Incorporated into the carbon skeleton. |