SECONDARY BATTERY AND BATTERY MODULE, BATTERY PACK, AND ELECTRIC APPARATUS CONTAINING SECONDARY BATTERY
A secondary battery and a battery module, a battery pack, and an electric apparatus containing the secondary battery are provided. The secondary battery includes a positive electrode plate and an electrolyte. The positive electrode plate includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer includes one or more of olivine-structured lithium-containing phosphate and its modified compound. The electrolyte includes an organic solvent, and the organic solvent includes a first solvent represented by Formula 1. R 11 and R 12 in Formula 1 each are independently one of C1-C4 alkyl and C1-C4 haloalkyl. The secondary battery satisfies: mass of first solvent/rated capacity of secondary battery is ≥0.7 g/Ah; and mass of electrolyte/rated capacity of secondary battery is ≤3.5 g/Ah.
1 . A secondary battery, comprising a positive electrode plate and an electrolyte, wherein
the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer comprises one or more of olivine-structured lithium-containing phosphate and its modified compound;
the electrolyte comprises an organic solvent, and the organic solvent comprises a first solvent represented by Formula 1;
R 11 and R 12 in Formula 1 each are independently one of C1-C4 alkyl and C1-C4 haloalkyl; and
the secondary battery satisfies:
mass of first solvent/rated capacity of secondary battery is ≥0.7 g/Ah; and
mass of electrolyte/rated capacity of secondary battery is ≤3.5 g/Ah.
2 . The secondary battery according to claim 1 , wherein the secondary battery further satisfies: proportion of first solvent/(thickness of positive electrode film layer×3+0.008/porosity of positive electrode film layer) is ≥1;
the proportion of the first solvent refers to a mass percentage of the first solvent in a total mass of the organic solvent; and
the thickness of the positive electrode film layer is a thickness of a positive electrode film layer on one surface of the positive electrode current collector, which is measured in mm.
3 . The secondary battery according to claim 1 , wherein the electrolyte further comprises an additive, and reduction potential of the additive is greater than or equal to 0.8 V vs Li + /Li.
4 . The secondary battery according to claim 3 , wherein the additive comprises an organic additive, and the organic additive comprises one or more of vinylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, ethylene sulfate, and 1,3-propane sultone.
5 . The secondary battery according to claim 3 , wherein the additive comprises an inorganic additive, and the inorganic additive comprises one or more of tris(trimethylsilyl) phosphate, lithium bis(oxalate)borate, lithium bis[ethanedioato(2-)-κO1,κO2]difluorophosphate(1-), lithium tetrafluoro(oxalato)phosphate, lithium difluoro(oxalato)borate, and lithium difluorophosphate.
6 . The secondary battery according to claim 4 , wherein a mass percentage of the organic additive in a total mass of the additive is greater than or equal to 50%.
7 . The secondary battery according to claim 4 , wherein a mass percentage of the inorganic additive in the total mass of the additive is less than or equal to 50%.
8 . The secondary battery according to claim 1 , wherein
the secondary battery further comprises a negative electrode plate, the negative electrode plate comprises a negative electrode active material, and the secondary battery further satisfies: (electrolyte retention coefficient×proportion of additive)/(relative mass of negative electrode×specific surface area of negative electrode active material×0.012+electrolyte retention coefficient×proportion of first solvent×0.03) is ≥1;
the electrolyte retention coefficient refers to a quotient calculated by dividing the mass of the electrolyte by the rated capacity of the secondary battery, and is measured in g/Ah;
the proportion of the additive refers to a mass percentage of the additive in a total mass of the electrolyte;
the relative mass of the negative electrode refers to a quotient calculated by dividing the mass of the negative electrode active material in the negative electrode plate by the rated capacity of the secondary battery, and is measured in g/Ah; and
the specific surface area of the negative electrode active material is measured in m 2 /g.
9 . The secondary battery according to claim 1 , wherein the thickness of the positive electrode film layer is greater than or equal to 0.07 mm; and/or
the porosity of the positive electrode film layer is less than or equal to 50%.
10 . The secondary battery according to claim 1 , wherein the relative mass of the negative electrode is less than or equal to 2.1 g/Ah;
the specific surface area of the negative electrode active material ranges from 0.5 m 2 /g to 6.0 m 2 /g; and/or
the proportion of the additive is greater than or equal to 3%.
11 . The secondary battery according to claim 1 , wherein the proportion of the first solvent is greater than or equal to 10%.
12 . The secondary battery according to claim 1 , wherein R 11 and R 12 in Formula 1 each are independently one of methyl, ethyl, propyl, butyl, fluoromethyl, fluoroethyl, fluoropropyl, and fluorobutyl.
13 . The secondary battery according to claim 1 , wherein the first solvent represented by Formula 1 is selected from one or more of the following compounds:
14 . The secondary battery according to claim 1 , wherein the organic solvent further comprises one or more of a second solvent represented by Formula 2 and a third solvent represented by Formula 3, R 21 in Formula 2 is one of H, methyl, and ethyl, and R 31 and R 32 in Formula 3 each are independently one of methyl, ethyl, and propyl;
15 . The secondary battery according to claim 14 , wherein a mass percentage of the second solvent in a total mass of the organic solvent is greater than or equal to 10%; and/or
a mass percentage of the third solvent in the total mass of the organic solvent is greater than or equal to 0%.
16 . The secondary battery according to claim 1 , wherein the olivine-structured lithium-containing phosphate comprises one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and their respective modified compounds.
17 . A battery module, comprising the secondary battery according to claim 1 .
18 . A battery pack, comprising one of the secondary battery according to claim 1 and the battery module according to claim 17 .
19 . An electric apparatus, comprising the secondary battery according to claim 1 .