Lithium-ion secondary battery

A lithium-ion secondary battery comprising a positive electrode plate, a negative electrode plate, a separator, and an electrolytic solution, wherein the positive electrode plate comprises a positive electrode current collector and a positive active material layer disposed on a surface of the positive electrode current collector and containing a positive active material, and the negative electrode plate comprises a negative electrode current collector and a negative active material layer disposed on a surface of the negative electrode current collector and containing a negative active material;

• wherein the positive active material comprises lithium iron phosphate, and the negative active material comprises graphite;
• wherein the positive electrode current collector and/or the negative electrode current collector are composite current collector, and the composite current collector comprises an organic support layer and a conductive layer disposed on at least one surface of the organic support layer;
• wherein the conductive layer has a thickness D1 of 300 nm<D1<2 μm and the organic support layer has a thickness D2 of 1 μm<D2<30 μm;
• and
• wherein the composite current collector has a thermal conductivity of 0.01 W/(m·K)˜2 W/(m·K).