Lithium ion power battery electrolyte and lithium ion secondary battery

Abstract

The invention discloses a lithium ion power battery electrolyte and a lithium ion secondary battery. The electrolyte comprises the following components in percentages by weight: 10% to 20% of a lithium salt mixture, 73% to 88.5% of a high voltage resistant organic solvent, 0.5% to 3% of a stabilizer and 1% to 4% of an auxiliary additive. The lithium salt of the electrolyte in the invention is composed of various lithium salts, and due to the synergistic effect of the various lithium salts, the stability of lithium hexafluorophate is improved; a nitriles solvent, a sulfones solvent and a fluorinated solvent with higher heat stability and higher oxidation potential are contained in the organic solvent, so that the electrolyte can work at relatively high temperature and voltage; the stabilizer is added into the electrolyte, water in the electrolyte can be absorbed, the generation of HF in the electrolyte is reduced, and an SEI film of the battery can be compacter and stabler through the introduction of a film-forming additive, so that the battery has preferable cycle performance.

Description

technical field

[0001] The invention relates to the technical field of lithium batteries, in particular to a lithium-ion power battery electrolyte and a lithium-ion secondary battery. Background technique

[0002] Lithium-ion batteries have gradually become the first choice for power batteries because of their high specific energy and high specific power, but they also have certain safety problems. Under some conditions, they may catch fire or even explode. It is caused by instability under conditions such as overcharge and high temperature, so it is particularly important to use a more stable electrolyte for power batteries. At present, the main components of commonly used power battery electrolytes are lithium salts, organic solvents and additives. The lithium salts used are mainly lithium hexafluorophosphate, and the organic solvents are mainly carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Class solvents, and common additives are ...

Examples

Embodiment 1

[0030] The electrolytic solution for a power battery provided in this embodiment includes a lithium salt mixture, a high-pressure-resistant organic solvent, a stabilizer and auxiliary additives, and the lithium salt mixture is based on lithium hexafluorophosphate (LiPF 6 ): Lithium bisfluorosulfonyl imide (LiFSI): Lithium difluorooxalate borate: Lithium difluorophosphate = 0.6:0.4:0.2:0.1 molar ratio, the lithium salt mixture accounts for 15% of the mass of the electrolyte, organic solvent Ethylene carbonate, ethyl methyl carbonate and sulfolane are mixed in a mass ratio of 3:5:2, and the organic solvent accounts for 80.2% of the mass of the electrolyte. The flame retardant is potassium perfluorobutanesulfonate (PNB), which accounts for 0.8% of the electrolyte mass, and the positive and negative electrode film-forming additives are ethylene carbonate (VEC), which accounts for 1% of the electrolyte mass, The stabilizer is heptamethyldisilazane, which accounts for 3% of the mass...

Embodiment 2

[0034] The electrolytic solution for a power battery provided in this embodiment includes a lithium salt mixture, a high-pressure-resistant organic solvent, a stabilizer and auxiliary additives, and the lithium salt mixture is based on lithium hexafluorophosphate (LiPF 6 ): bisfluorosulfonimide Lithium (LiFSI): lithium difluorooxalate borate: lithium difluorophosphate = 0.6:0.4:0.2:0.1 molar ratio to form a lithium salt mixture accounting for 15% of the mass of the electrolyte. Described organic solvent is that propylene carbonate, dimethyl carbonate, adiponitrile are mixed with the ratio of 3:5:2 in mass ratio, and the 79.8% flame retardant that organic solvent accounts for electrolyte quality is trimethyl phosphite, It accounts for 3% of the mass of the electrolyte, the positive and negative film-forming additives are ammonium perfluorooctanoate (APC), which accounts for 0.7% of the mass of the electrolyte, and the stabilizer is heptamethyldisilazane, which accounts for 0.7% ...

Embodiment 3

[0038] The electrolytic solution for a power battery provided in this embodiment includes a lithium salt mixture, a high-voltage resistant organic solvent, a stabilizer and auxiliary additives, and the lithium salt mixture is made of lithium hexafluorophosphate (LiPF 6 ): Lithium bisfluorosulfonyl imide (LiFSI): Lithium difluorooxalate borate: Lithium difluorophosphate=0.6:0.4:0.2:0.1 molar ratio composition The lithium salt mixture accounts for 15% of the mass of the electrolyte. The organic solvent is a mixed solvent mixed with ethylene carbonate, diethyl carbonate and hexafluoroisopropyl ethyl ether in a mass ratio of 2.5:6:1.5, the organic solvent accounts for 81% of the mass of the electrolyte, and the flame retardant is hexamethylphosphorus Nitrile, which accounts for 2% of the mass of the electrolyte, positive and negative film-forming additives are isocyanates, which account for 1.5% of the mass of the electrolyte, stabilizers are hexamethyldisilazane, which account for...

technical field

[0001] The invention relates to the technical field of lithium batteries, in particular to a lithium-ion power battery electrolyte and a lithium-ion secondary battery. Background technique

[0002] Lithium-ion batteries have gradually become the first choice for power batteries because of their high specific energy and high specific power, but they also have certain safety problems. Under some conditions, they may catch fire or even explode. It is caused by instability under conditions such as overcharge and high temperature, so it is particularly important to use a more stable electrolyte for power batteries. At present, the main components of commonly used power battery electrolytes are lithium salts, organic solvents and additives. The lithium salts used are mainly lithium hexafluorophosphate, and the organic solvents are mainly carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Class solvents, and common additives are ...

Examples

Embodiment 1

[0030] The electrolytic solution for a power battery provided in this embodiment includes a lithium salt mixture, a high-pressure-resistant organic solvent, a stabilizer and auxiliary additives, and the lithium salt mixture is based on lithium hexafluorophosphate (LiPF 6 ): Lithium bisfluorosulfonyl imide (LiFSI): Lithium difluorooxalate borate: Lithium difluorophosphate = 0.6:0.4:0.2:0.1 molar ratio, the lithium salt mixture accounts for 15% of the mass of the electrolyte, organic solvent Ethylene carbonate, ethyl methyl carbonate and sulfolane are mixed in a mass ratio of 3:5:2, and the organic solvent accounts for 80.2% of the mass of the electrolyte. The flame retardant is potassium perfluorobutanesulfonate (PNB), which accounts for 0.8% of the electrolyte mass, and the positive and negative electrode film-forming additives are ethylene carbonate (VEC), which accounts for 1% of the electrolyte mass, The stabilizer is heptamethyldisilazane, which accounts for 3% of the mass...

Embodiment 2

[0034] The electrolytic solution for a power battery provided in this embodiment includes a lithium salt mixture, a high-pressure-resistant organic solvent, a stabilizer and auxiliary additives, and the lithium salt mixture is based on lithium hexafluorophosphate (LiPF 6 ): bisfluorosulfonimide Lithium (LiFSI): lithium difluorooxalate borate: lithium difluorophosphate = 0.6:0.4:0.2:0.1 molar ratio to form a lithium salt mixture accounting for 15% of the mass of the electrolyte. Described organic solvent is that propylene carbonate, dimethyl carbonate, adiponitrile are mixed with the ratio of 3:5:2 in mass ratio, and the 79.8% flame retardant that organic solvent accounts for electrolyte quality is trimethyl phosphite, It accounts for 3% of the mass of the electrolyte, the positive and negative film-forming additives are ammonium perfluorooctanoate (APC), which accounts for 0.7% of the mass of the electrolyte, and the stabilizer is heptamethyldisilazane, which accounts for 0.7% ...

Embodiment 3

[0038] The electrolytic solution for a power battery provided in this embodiment includes a lithium salt mixture, a high-voltage resistant organic solvent, a stabilizer and auxiliary additives, and the lithium salt mixture is made of lithium hexafluorophosphate (LiPF 6 ): Lithium bisfluorosulfonyl imide (LiFSI): Lithium difluorooxalate borate: Lithium difluorophosphate=0.6:0.4:0.2:0.1 molar ratio composition The lithium salt mixture accounts for 15% of the mass of the electrolyte. The organic solvent is a mixed solvent mixed with ethylene carbonate, diethyl carbonate and hexafluoroisopropyl ethyl ether in a mass ratio of 2.5:6:1.5, the organic solvent accounts for 81% of the mass of the electrolyte, and the flame retardant is hexamethylphosphorus Nitrile, which accounts for 2% of the mass of the electrolyte, positive and negative film-forming additives are isocyanates, which account for 1.5% of the mass of the electrolyte, stabilizers are hexamethyldisilazane, which account for...

Images