| 摘要 |
This lithium ion secondary battery has a positive electrode comprising a positive electrode active substance layer formed on a positive electrode collector and a negative electrode comprising a negative electrode active substance layer formed on a negative electrode collector, said positive electrode and negative electrode being layered alternately with a separator therebetween. The lithium ion secondary battery is characterized by a protective layer containing an oxide particle and a binding agent formed on the active substance layer surface of at least either the positive electrode or the negative electrode, and a water absorption rate for the protective layer that is greater than 0 and less than or equal to 0.1% under the following conditions: <Conditions> The surface of a metal foil is coated with a slurry containing the binding agent and the oxide particle, and when a fragment of the sheet has dried at 85°C until the solvent contained in the coating layer has reached 1,000 ppm or lower, the rate of mass increase in the portion excluding the metal foil between before and after drying is measured. |
