Abstract: Provided is a light-transmissive battery that transmits visible light. A light-transmissive battery includes a positive electrode including an insulating transparent cover body and a positive-electrode current collector layer and a positive electrode layer sequentially stacked over the insulating transparent cover body; a negative electrode including an insulating transparent cover body and a negative-electrode current collector layer and a negative electrode layer sequentially stacked over the insulating transparent cover body; and a transparent electrolyte disposed between the positive electrode layer and the negative electrode layer that are opposed to each other. Each of the positive-electrode current collector layer, the negative-electrode current collector layer, the positive electrode layer, and negative electrode layer is formed to a thickness that allows the layer to transmit visible light.

Abstract: A battery is appropriately housed in a transparent body. A transparent body includes: a transparent body main part; a defogger that removes fog on the transparent body main part; and a battery that supplies electric power to the defogger. The battery includes: a positive electrode where a transparent positive electrode conductive film and a transparent positive electrode layer are laminated on an insulating transparent positive electrode side housing; a negative electrode where a transparent negative electrode conductive film and a transparent negative electrode layer are laminated on an insulating transparent negative electrode side housing; and a transparent electrolyte layer that is arranged between the positive electrode layer and the negative electrode layer which face each other.

Abstract: Provided is a sodium secondary battery that has visible light transparency and is excellent in flexibility. A sodium secondary battery includes: a positive electrode film that contains a material formed on a flexible transparent film substrate, the material being capable of intercalating and deintercalating sodium ions; a transparent electrolyte having sodium ion conductivity; and a negative electrode film that if formed of a material formed on a flexible transparent film substrate, the material being capable of dissolving and depositing sodium or intercalating and deintercalating sodium ions. When the positive electrode film contains a sodium source, the negative electrode film is made to have a thickness of 30 nm to 200 nm by using, as a negative electrode material, any of tin oxide, silicon oxide, titanium oxide, tungsten oxide, niobium oxide, molybdenum oxide, metal phosphide, metal sulfide, metal nitride, metal fluoride, or metal titanium composite oxide.