SECONDARY BATTERY

Disclosed is a secondary battery including a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode, wherein the positive electrode includes a positive electrode current collector, and a positive electrode active material layer disposed on the positive electrode current collector and containing a positive electrode active material and a binder, the positive electrode active material includes a lithium cobalt oxide, the lithium cobalt oxide has a bimodal shape of average particle diameter distribution including two types of particles having a different average particle diameter, the lithium cobalt oxide includes 5,000 ppm or more of Al doping and is surface-coated with Zr, the negative electrode includes a negative electrode current collector, and a negative electrode active material layer disposed on the negative electrode current collector and containing a negative electrode active material and a binder, and the negative electrode active material includes a first negative electrode active material that is an artificial graphite having no carbon coating layer on the surface thereof, and a second negative electrode active material that is an artificial graphite having a carbon coating layer on the surface thereof.