An electrode active material that realizes a high capacity density and permits takeout of a large current; and a battery that is high in energy density and realizes a large output. There is provided a battery comprising as constituents thereof at least a positive electrode, a negative electrode and an electrolyte, wherein as an electrode active material of at least one of the positive electrode and negative electrode, use is made of a polyradical compound having a partial structure of the general formula: (2) wherein each of R¹ to R³ independently is a hydrogen atom or methyl, and each of R⁴ to R⁷ independently is a C₁-C₃ alkyl.