A secondary battery comprising a positive electrode plate, a negative electrode plate, a separator and an electrolyte, the positive electrode plate comprising a positive electrode current collector and a positive electrode film layer coated on at least one surface of the positive electrode current collector and containing a positive electrode active material, the negative electrode plate comprising a negative electrode current collector and a negative electrode film layer coated on at least one surface of the negative electrode current collector and containing a negative electrode active material, characterized in that: the positive electrode active material comprises one or more of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide; the negative active material comprises a silicon-based material; and the secondary battery satisfies the following formula I: 2 ≤ AF / AE − 1 / CE / CF − 1 ≤ 7 in which CF represents a unit cell volume as measured when the positive electrode active material is prepared into a button battery and the button battery is charged to 100% SOC at a rate of 0.05C; CE represents a unit cell volume as measured when the positive electrode active material is prepared into a button battery and the button battery is discharged to 0% SOC at a rate of 0.05C; AF represents a volume of the negative electrode active material particles as measured when the silicon-based material is prepared into a single-particle battery, and the single-particle battery is charged to 100% SOC at a rate of 0.5C; and AE represents a volume of the negative electrode active material particles as measured when the silicon-based material is prepared into a single-particle battery, and the single-particle battery is discharged to 0% SOC at a rate of 0.5C; wherein the silicon-based material is present in the negative electrode active material in a mass percentage of 15% to 30%. the positive electrode active material comprises one or more of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide; the negative active material comprises a silicon-based material; and the secondary battery satisfies the following formula I: 2 ≤ AF / AE − 1 / CE / CF − 1 ≤ 7 in which CF represents a unit cell volume as measured when the positive electrode active material is prepared into a button battery and the button battery is charged to 100% SOC at a rate of 0.05C; CE represents a unit cell volume as measured when the positive electrode active material is prepared into a button battery and the button battery is discharged to 0% SOC at a rate of 0.05C; AF represents a volume of the negative electrode active material particles as measured when the silicon-based material is prepared into a single-particle battery, and the single-particle battery is charged to 100% SOC at a rate of 0.5C; and AE represents a volume of the negative electrode active material particles as measured when the silicon-based material is prepared into a single-particle battery, and the single-particle battery is discharged to 0% SOC at a rate of 0.5C; wherein the silicon-based material is present in the negative electrode active material in a mass percentage of 15% to 30%. CF represents a unit cell volume as measured when the positive electrode active material is prepared into a button battery and the button battery is charged to 100% SOC at a rate of 0.05C; CE represents a unit cell volume as measured when the positive electrode active material is prepared into a button battery and the button battery is discharged to 0% SOC at a rate of 0.05C; AF represents a volume of the negative electrode active material particles as measured when the silicon-based material is prepared into a single-particle battery, and the single-particle battery is charged to 100% SOC at a rate of 0.5C; and AE represents a volume of the negative electrode active material particles as measured when the silicon-based material is prepared into a single-particle battery, and the single-particle battery is discharged to 0% SOC at a rate of 0.5C; wherein the silicon-based material is present in the negative electrode active material in a mass percentage of 15% to 30%.