LITHIUM-ION SECONDARY BATTERY

The present invention provides a lithium-ion secondary battery, which comprises a positive electrode plate, a negative electrode plate, a separator and an electrolyte. The positive electrode plate comprises a positive current collector and a positive film, the positive film is provided on at least one surface of the positive current collector and comprises a positive active material, and that the positive active material of the positive film is one or more selected from a group consisting of LiFe1-yMnyPO4 and a doping and/or coating modified compound thereof, wherein 0≤y≤1, and the lithium-ion secondary battery satisfies a relationship: 3.5≤(m×C)/(ρ×Cap)≤6.5, m represents a total mass of the electrolyte inside the formated battery with a unit of g, ρ represents a density of the electrolyte with a unit of g/cm3, C represents a concentration of the lithium salt in the electrolyte with a unit of mol/L, Cap represents a rated capacity of the battery with a unit of Ah.