Abstract: A lithium ion secondary battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer is provided. The positive electrode layer includes a positive electrode current collector layer and a positive electrode active material layer. Positive electrode active material layer includes a positive electrode active material. The negative electrode layer includes a negative electrode current collector layer and a negative electrode active material layer. The negative electrode active material layer includes a negative electrode active material. Solid electrolyte layer between the positive and negative electrode active material layers includes a solid electrolyte. At least one of a ratio of a particle diameter of the solid electrolyte to a particle diameter of the positive electrode active material and a ratio of the particle diameter of the solid electrolyte to a particle diameter of the negative electrode active material is in the range of 1/10 to 1/3.

Abstract: A provided lithium ion secondary battery includes a pair of electrodes and a solid electrolyte layer. The solid electrolyte layer is provided between the pair of electrodes and includes titanium aluminum lithium phosphate. At least one of the pair of electrodes includes vanadium lithium phosphate. At least one of the pair of electrodes includes at least one constituent of titanium and aluminum. The amount of the at least one constituent existing on a side opposite to the solid electrolyte layer is smaller than the amount of the at least one constituent existing on the solid electrolyte layer side.

Abstract: A lithium ion secondary battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer is provided. The positive electrode layer includes a positive electrode current collector layer and a positive electrode active material layer. The positive electrode active material layer includes a positive electrode active material. The negative electrode layer includes a negative electrode current collector layer and a negative electrode active material layer. The negative electrode active material layer includes a negative electrode active material. The solid electrolyte layer between the positive and negative electrode active material layers includes a solid electrolyte. At least one of a ratio of a particle diameter of the solid electrolyte to a particle diameter of the positive electrode active material and a ratio of the particle diameter of the solid electrolyte to a particle diameter of the negative electrode active material ranges from 3.0 to 10.0.