Isoquinolinone additive, electrolyte and high-voltage lithium ion battery

Abstract

The invention belongs to the technical field of batteries, and particularly relates to an isoquinolinone additive, an electrolyte and a high-voltage lithium ion battery. Compared with the prior art, the novel additive molecule provided by the invention can be used for a high-voltage LNMO material system, the oxidation resistance and wettability of an electrolyte can be improved, and the high-voltage normal-temperature cycle performance is obviously improved; the substance with cyclic and cyano bifunctional groups reduces the decomposition effect of the electrode on the electrolyte; a CEI film with high stability is formed on the surface of the positive pole piece, so that the cycle performance of the battery can be improved; additive molecules can better improve the cycle performance of the battery through the synergistic effect of C = C double bonds and C-N triple bonds; the reaction additive, as an in-situ solid polymer, can be initiated by the initiator to polymerize in the soft package to form a layer of firm oligomer, so that the voltage resistance of the soft package battery is improved, and the reaction additive is applied to high-voltage circulation.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries, and in particular relates to an isoquinolinone additive, an electrolyte and a high-voltage lithium-ion battery. Background Art

[0002] As an energy storage technology that can be repeatedly charged and discharged, lithium-ion batteries have achieved very important and successful applications in the past 20 years, especially as a power source for various mobile electronic devices, promoting the vigorous development of industries such as communications and electronics.

[0003] At present, there are two basic routes for the development of lithium-ion batteries, one is large power batteries, and the other is small batteries in the 3C field. Regardless of the field, with the improvement of living standards, lithium-ion batteries are required to have high energy density. There are two ways to improve the energy density of lithium-ion batteries: one is to increase the specific capacity of positive and negative electrode materials; the other is to increase the delithiation potential of positive electrode materials and reduce the delithiation potential of negative electrode materials.

[0004] The deintercalation potential of the positive electrode materials of lithium-ion batteries currently used, such as spinel LiMn2O4, layered LiCoO2 and LiNiO2, is generally 4.0V, collectively referred to as 4V positive electrode materials. For example, the discharge voltage of LiCoO2 relative to the Li / Li+ electrode is about 3.7V. Compared with the positive electrode material of the same capacity of 5V, the battery energy density of 5V positive electrode material can be increased by about 35%. Therefore, the research and development of 5V high voltage positive electrode materials has also attracted more and more attention from many researchers recently.

[0005] LiNi with spinel-like crystal structure 0.5 Mn 1.5 O4 and LiMPO4 (M = Co, Ni) with olivine crystal structure are the two most promising 5V high voltage positive electrode materials. Although LiMPO4 (M = Co, Ni) with olivine structure has a higher theoretical capacity, its cycle performance still needs to be greatly improved to have a good application prospect. LiNi with spinel structure 0.5 Mn 1.5 O4 has both high voltage and good cycle performance, and its application prospects are broad.

[0006] An important factor restricting the industrialization of lithium nickel manganese oxide is that the current commercial electrolyte cannot meet its application requirements. The current commercial organic electrolyte is 1M LiPF6 dissolved in EC:DEC or EC:DMC, and its potential window Eg range is about 1V to 4.5V. However, the potential platform of high-voltage lithium nickel manganese oxide materials is around 4.7V, and its charge and discharge range is generally 3.5 to 5V, which has exceeded the potential window of current commercial organic electrolytes. Therefore, the electrolyte is easily oxidized during the charge and discharge process. In addition, when the potential is as high as about 5V during the charging process, a high concentration of highly oxidizing Mn is formed in the highly delithiated spinel particles. 4+ and Ni 4 + , and the electrolyte on the electrode surface will be constantly oxidized and decomposed, generating carbonaceous nanostructures, which are loaded onto the surface of the material to form a carbonized film. This phenomenon is particularly serious at high temperatures. The presence of this film hinders the normal deintercalation of lithium ions. As the number of cycles increases, the amount of reversible lithium intercalation will become less and less, resulting in serious capacity decay. At the same time, trace water in the electrolyte will produce protons H during the charge and discharge process, which react with the electrolyte to generate HF. HF is highly corrosive and reacts with the contacting positive electrode material to corrode the positive electrode material. In addition, the current commercial electrolytes mainly use carbonate solvents, which will undergo oxidative decomposition at a voltage of about 4.5V. Not only can a stable charge and discharge platform and high cycle efficiency not be obtained, resulting in deterioration of battery performance, but also lithium-ion batteries will swell, causing serious safety problems.

[0007] Therefore, from the perspective of practical use, the primary problem that must be solved is to prepare a high-voltage electrolyte that matches the lithium nickel manganese oxide material. Summary of the invention

[0008] In view of this, the technical problem to be solved by the present invention is to provide an isoquinolone additive, an electrolyte and a high-voltage lithium-ion battery. The isoquinolone additive is an additive molecule that can undergo in-situ polymerization. In the soft-pack battery, a layer of oligomeric compounds can be generated to work together with the SEI film to protect the positive and negative electrode materials. In addition, the electrolyte after the second injection continuously replenishes the positive and negative electrode protective layers damaged under high-voltage cycling during the cycling process, thereby improving the high-voltage cycling performance.

[0009] The present invention provides an isoquinolinone additive having a structure shown in formula (I) or formula (II):

[0010]

[0011]

[0012] Wherein, R1, R2, R3, R4 and R5 in formula (I) and formula (III) are independently selected from hydrogen, halogen atoms, C1-C20 cyano groups, sulfonic acid groups, C1-C20 sulfonyl groups, substituted or unsubstituted C1-C20 alkyl groups, substituted or unsubstituted C2-C20 alkenyl groups, substituted or unsubstituted C6-C26 aryl groups, substituted or unsubstituted C1-C20 alkoxy groups, substituted or unsubstituted C6-C26 aryloxy groups;

[0013] In formula (II), R1 is selected from C1-C20 cyano, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl;

[0014] In formula (II), R2, R3, R4 and R5 are each independently selected from hydrogen, a halogen atom, a C1-C20 cyano group, a sulfonic acid group, a C1-C20 sulfonyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C6-C26 aryl group, a substituted or unsubstituted C1-C20 alkoxy group, or a substituted or unsubstituted C6-C26 aryloxy group;

[0015] The substituents in the substituted C1-C20 alkyl, substituted C2-C20 alkenyl, substituted C6-C26 aryl, substituted C1-C20 alkoxy and substituted C6-C26 aryloxy are independently selected from one or more of halogen atoms, sulfonic acid groups, C1-C20 sulfonyl groups, C6-C26 aryl groups, C1-C20 alkoxy and C6-C26 aryloxy groups.

[0016] Preferably, in formula (I) and formula (III), R1, R2, R3, R4 and R5 are independently selected from hydrogen, halogen atoms, C1-C10 cyano groups, sulfonic acid groups, C1-C10 sulfonyl groups, substituted or unsubstituted C1-C10 alkyl groups, substituted or unsubstituted C2-C10 alkenyl groups, substituted or unsubstituted C6-C10 aryl groups, substituted or unsubstituted C1-C10 alkoxy groups, substituted or unsubstituted C6-C10 aryloxy groups;

[0017] In formula (II), R1 is selected from C1-C10 cyano, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C2-C10 alkenyl;

[0018] In formula (II), R2, R3, R4 and R5 are each independently selected from hydrogen, a halogen atom, a C1-C10 cyano group, a sulfonic acid group, a C1-C10 sulfonyl group, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C2-C10 alkenyl group, a substituted or unsubstituted C6-C10 aryl group, a substituted or unsubstituted C1-C10 alkoxy group, or a substituted or unsubstituted C6-C10 aryloxy group;

[0019] The substituents in the substituted C1-C10 alkyl, substituted C2-C10 alkenyl, substituted C6-C10 aryl, substituted C1-C10 alkoxy and substituted C6-C10 aryloxy are each independently selected from halogen atoms.

[0020] Preferably, the film-forming additive is selected from one or more of A-1 to A-6;

[0021]

[0022] The present invention also provides a method for preparing an isoquinolinone additive, comprising the following steps:

[0023] S1) reacting reactant 1 represented by formula (A) or formula (B) with reactant 2 in the presence of a catalyst to obtain reactant 3 represented by formula (C) or formula (D);

[0024] S2) reacting the reactant 3 with the reactant 4 to obtain an isoquinolinone additive;

[0025]

[0026] X is a halogen atom;

[0027] In formula (A) and formula (C), R1 is selected from hydrogen, halogen atom, C1-C20 cyano group, sulfonic acid group, C1-C20 sulfonyl group, substituted or unsubstituted C1-C20 alkyl group, substituted or unsubstituted C2-C20 alkenyl group, substituted or unsubstituted C6-C26 aryl group, substituted or unsubstituted C1-C20 alkoxy group, substituted or unsubstituted C6-C26 aryloxy group;

[0028] In formula (B) and formula (D), R1 is selected from C1-C20 cyano, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl;

[0029] R2, R3, R4 and R5 are each independently selected from hydrogen, a halogen atom, a C1-C20 cyano group, a sulfonic acid group, a C1-C20 sulfonyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C6-C26 aryl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C6-C26 aryloxy group;

[0030] The substituents in the substituted C1-C20 alkyl, substituted C2-C20 alkenyl, substituted C6-C26 aryl, substituted C1-C20 alkoxy and substituted C6-C26 aryloxy are independently selected from one or more of halogen atoms, sulfonic acid groups, C1-C20 sulfonyl groups, C6-C26 aryl groups, C1-C20 alkoxy and C6-C26 aryloxy groups.

[0031] Preferably, the catalyst comprises a palladium catalyst and an iodine salt; the molar ratio of reactant 1, reactant 2, palladium catalyst and iodine salt is (0.8-1.2):(2-3):((0.1-0.3):(0.9-1.2);

[0032] And / or, the reaction temperature in step S1) is 80°C to 120°C.

[0033] The present invention also provides an electrolyte, characterized in that it comprises the above-mentioned isoquinolinone additive.

[0034] Preferably, the mass of the isoquinolinone additive is 1% to 5% of the mass of the electrolyte;

[0035] And / or, the electrolyte further comprises an organic solvent, a lithium salt and a film-forming additive;

[0036] The mass of the organic solvent is 60% to 80% of the mass of the electrolyte;

[0037] The mass of the lithium salt is 10% to 18% of the mass of the electrolyte;

[0038] The mass of the film-forming additive is 1% to 10% of the mass of the electrolyte.

[0039] Preferably, the organic solvent is selected from one or more of organic esters, ether solvents, sulfone solvents, nitrile solvents and amide solvents; the organic ester is selected from ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethyl formate, ethyl acetate, propyl acetate, propyl propionate, γ-butyrolactone, methyl trifluoroethyl carbonate, fluoroethylene carbonate and di(2,2,2-trifluoroethylene carbonate). The ether solvent is selected from one or more of dimethyl ether, diethyl ether, methyl ethyl ether, ethylene glycol dimethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether and 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether; the sulfone solvent is selected from sulfolane; the nitrile solvent is selected from acetonitrile; the amide solvent is selected from 1-methyl-3-ethylcarbonylquinonebis(trifluoromethylsulfonyl)imide;

[0040] And / or, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium bis(trifluoromethylsulfonyl imide), lithium bis(fluorosulfonyl imide), lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium difluorobis(oxalatophosphate) and lithium tetrafluorooxalatophosphate;

[0041] And / or, the film-forming additive is selected from one or more of vinylene carbonate, lithium difluorooxalatoborate, vinyl ethylene carbonate, fluoroethylene carbonate and vinyl sulfite.

[0042] The present invention also provides a secondary injection combined electrolyte, comprising a first injection electrolyte, an initiator and a second injection electrolyte;

[0043] The first injection electrolyte and the second injection electrolyte are independently selected from the above-mentioned electrolytes.

[0044] The present invention also provides a high-voltage lithium-ion battery, comprising the above-mentioned electrolyte or the above-mentioned secondary injection combined electrolyte.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] 1) The new additive molecule provided by the present invention can be used in a high-voltage LNMO material system to solve the problem that the oxidation decomposition potential of the electrolyte cannot reach 5V. The additive molecule can improve the oxidation resistance and wettability of the electrolyte and significantly improve the high-voltage room-temperature cycle performance;

[0047] 2) The isoquinolinone additive provided by the present invention is a cyanocyclic unsaturated hydrocarbon compound, which is a substance with a cyclic and cyano bifunctional group. The cyano group is a carbon-nitrogen triple bond with strong polarity, strong electron-withdrawing properties, strong oxidation resistance, good stability on the positive electrode, and also has strong coordination ability, which can be combined with the active sites on the electrode surface to mask the active ions on the positive electrode surface and reduce the decomposition effect of the electrode on the electrolyte;

[0048] 3) The unsaturation degree of the CN triple bond of the cyano group is higher than that of the CN double bond of the carbonylquinoline, so it will be preferentially decomposed to form a CEI film with high stability on the surface of the positive electrode. The carbonylquinoline compound can react secondary on the surface of the CEI film at a high potential to form an electrolyte membrane with a certain conductivity. The use of the cyano carbonylquinoline compound additive of the present invention can improve the cycle performance of the battery;

[0049] 4) The additive molecules provided by the present invention can be synergistically reacted by the C=C double bond and the CN triple bond. The synergistic effect is mainly reflected in that the CN triple bond is preferentially decomposed to form an inorganic layer SEI, and then the C=C double bond is decomposed to form an organic layer SEI, and then the trimethylsilyl group participates in forming a new inorganic layer SEI layer. Due to the characteristics of the trimethylsilyl group, the outer SEI layer can better contact the electrolyte. Finally, this special three-layer SEI film can better improve the cycle performance of the battery;

[0050] 5) The reaction additive, as an in-situ solid polymer, can be initiated by an initiator to polymerize inside the soft pack to form a layer of solid oligomers, thereby improving the pressure resistance of the soft pack battery and being applied to high voltage cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a graph showing the test results of the oxidation decomposition potential of the additive molecules provided by the present invention. DETAILED DESCRIPTION

[0052] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0053] The present invention provides an isoquinolinone additive, characterized in that it has a structure shown in formula (I) or formula (II):

[0054]

[0055] Wherein, R1, R2, R3, R4 and R5 in formula (I) and formula (III) are each independently hydrogen, halogen, C1-C20 cyano, sulfonic acid, C1-C20 sulfonyl, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C6-C26 aryl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C6-C20 alkyl, C26 aryloxy; the substituents in the substituted C1~C20 alkyl, substituted C2~C20 alkenyl, substituted C6~C26 aryl, substituted C1~C20 alkoxy and substituted C6~C26 aryloxy are each independently one or more of halogen atoms, sulfonic acid groups, C1~C20 sulfonyl groups, C6~C26 aryl groups, C1~C20 alkoxy and C6~C26 aryloxy.

[0056] Specifically, R1, R2, R3, R4 and R5 are each independently hydrogen, a halogen atom, a C1-C10 cyano group, a sulfonic acid group, a C1-C10 sulfonyl group, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C2-C10 alkenyl group, a substituted or unsubstituted C6-C16 aryl group, a substituted or unsubstituted C1-C10 alkoxy group, or a substituted or unsubstituted C6-C16 aryloxy group; the substituents in the substituted C1-C10 alkyl group, the substituted C2-C10 alkenyl group, the substituted C6-C16 aryl group, the substituted C1-C10 alkoxy group and the substituted C6-C16 aryloxy group are each independently one or more of a halogen atom, a sulfonic acid group, a C1-C10 sulfonyl group, a C6-C16 aryl group, a C1-C10 alkoxy group and a C6-C16 aryloxy group.

[0057] More specifically, R1, R2, R3, R4 and R5 are each independently hydrogen, a halogen atom, a C1-C5 cyano group, a sulfonic acid group, a C1-C5 sulfonyl group, a substituted or unsubstituted C1-C5 alkyl group, a substituted or unsubstituted C2-C5 alkenyl group, a substituted or unsubstituted C6-C10 aryl group, a substituted or unsubstituted C1-C5 alkoxy group, or a substituted or unsubstituted C6-C10 aryloxy group; and the substituents in the substituted C1-C5 alkyl group, the substituted C2-C5 alkenyl group, the substituted C6-C10 aryl group, the substituted C1-C5 alkoxy group and the substituted C6-C10 aryloxy group are each independently one or more of a halogen atom, a sulfonic acid group, a C1-C5 sulfonyl group, a C6-C10 aryl group, a C1-C5 alkoxy group and a C6-C10 aryloxy group.

[0058] More specifically, R1, R2, R3, R4 and R5 are each independently hydrogen, a halogen atom, a C1-C3 cyano group, a sulfonic acid group, a C1-C3 sulfonyl group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C2-C3 alkenyl group, a substituted or unsubstituted C6-C10 aryl group, a substituted or unsubstituted C1-C3 alkoxy group, or a substituted or unsubstituted C6-C10 aryloxy group; and the substituents in the substituted C1-C3 alkyl group, the substituted C2-C3 alkenyl group, the substituted C6-C10 aryl group, the substituted C1-C3 alkoxy group and the substituted C6-C10 aryloxy group are each independently one or more of a halogen atom, a sulfonic acid group, a C1-C3 sulfonyl group, a C6-C10 aryl group, a C1-C3 alkoxy group and a C6-C10 aryloxy group.

[0059] In formula (II), R1 is C1-C20 cyano, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl, preferably C1-C10 cyano, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C2-C10 alkenyl, more preferably C1-C5 cyano, substituted or unsubstituted C1-C5 alkyl, substituted or unsubstituted C2-C5 alkenyl, and even more preferably C1-C3 cyano, substituted or unsubstituted C1-C3 alkyl, substituted or unsubstituted C2-C3 alkenyl.

[0060] In formula (II), R2, R3, R4 and R5 are each independently hydrogen, a halogen atom, a C1-C20 cyano group, a sulfonic acid group, a C1-C20 sulfonyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C6-C26 aryl group, a substituted or unsubstituted C1-C20 alkoxy group, or a substituted or unsubstituted C6-C26 aryloxy group; and the substituents in the substituted C1-C20 alkyl group, the substituted C2-C20 alkenyl group, the substituted C6-C26 aryl group, the substituted C1-C20 alkoxy group and the substituted C6-C26 aryloxy group are each independently selected from one or more of a halogen atom, a sulfonic acid group, a C1-C20 sulfonyl group, a C6-C26 aryl group, a C1-C20 alkoxy group and a C6-C26 aryloxy group.

[0061] Specifically, R2, R3, R4 and R5 in the formula (II) are each independently hydrogen, a halogen atom, a C1-C10 cyano group, a sulfonic acid group, a C1-C10 sulfonyl group, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C2-C10 alkenyl group, a substituted or unsubstituted C6-C16 aryl group, a substituted or unsubstituted C1-C10 alkoxy group, or a substituted or unsubstituted C6-C16 aryloxy group; the substituents in the substituted C1-C10 alkyl group, the substituted C2-C10 alkenyl group, the substituted C6-C16 aryl group, the substituted C1-C10 alkoxy group and the substituted C6-C16 aryloxy group are each independently selected from one or more of a halogen atom, a sulfonic acid group, a C1-C10 sulfonyl group, a C6-C16 aryl group, a C1-C10 alkoxy group and a C6-C16 aryloxy group.

[0062] More specifically, in the formula (II), R2, R3, R4 and R5 are each independently hydrogen, a halogen atom, a C1-C5 cyano group, a sulfonic acid group, a C1-C5 sulfonyl group, a substituted or unsubstituted C1-C5 alkyl group, a substituted or unsubstituted C2-C5 alkenyl group, a substituted or unsubstituted C6-C10 aryl group, a substituted or unsubstituted C1-C5 alkoxy group, or a substituted or unsubstituted C6-C10 aryloxy group; and the substituents in the substituted C1-C5 alkyl group, the substituted C2-C5 alkenyl group, the substituted C6-C10 aryl group, the substituted C1-C5 alkoxy group and the substituted C6-C10 aryloxy group are each independently selected from one or more of a halogen atom, a sulfonic acid group, a C1-C5 sulfonyl group, a C6-C10 aryl group, a C1-C5 alkoxy group and a C6-C10 aryloxy group.

[0063] More specifically, in the formula (II), R2, R3, R4 and R5 are each independently hydrogen, a halogen atom, a C1-C3 cyano group, a sulfonic acid group, a C1-C3 sulfonyl group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C2-C3 alkenyl group, a substituted or unsubstituted C6-C10 aryl group, a substituted or unsubstituted C1-C3 alkoxy group, or a substituted or unsubstituted C6-C10 aryloxy group; and the substituents in the substituted C1-C3 alkyl group, the substituted C2-C3 alkenyl group, the substituted C6-C10 aryl group, the substituted C1-C3 alkoxy group and the substituted C6-C10 aryloxy group are each independently selected from one or more of a halogen atom, a sulfonic acid group, a C1-C3 sulfonyl group, a C6-C10 aryl group, a C1-C3 alkoxy group and a C6-C10 aryloxy group.

[0064] The halogen atom may be any halogen atom known to those skilled in the art without any particular limitation. In the present invention, it is preferably F, Cl or Br, and more preferably Cl or F.

[0065] In the present invention, most preferably, the film-forming additive is one or more of A-1 to A-6;

[0066]

[0067] The isoquinolinone additive provided by the present invention is an in-situ solid polymer, which can be initiated by an initiator to polymerize inside the soft pack to form a layer of solid oligomers, thereby improving the pressure resistance of the soft pack battery and being applied to high voltage cycling. The general reaction equation of the polymerization reaction is:

[0068]

[0069] The present invention also provides a method for preparing the above-mentioned isoquinolinone additive, comprising the following steps: S1) reacting reactant 1 represented by formula (A) or formula (B) with reactant 2 in the presence of a catalyst to obtain reactant 3 represented by formula (C) or formula (D); S2) reacting reactant 3 with reactant 4 to obtain an isoquinolinone additive.

[0070]

[0071] X is a halogen atom, preferably F, Cl or Br, more preferably Cl.

[0072] In formula (A) and formula (C), R1 is hydrogen, a halogen atom, a C1-C20 cyano group, a sulfonic acid group, a C1-C20 sulfonyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C6-C26 aryl group, a substituted or unsubstituted C1-C20 alkoxy group, or a substituted or unsubstituted C6-C26 aryloxy group; R1 in formula (A) and formula (C) is the same as R1 in the above formula (I), and will not be repeated here.

[0073] In formula (B) and formula (D), R1 is C1-C20 cyano, substituted or unsubstituted C1-C20 alkyl, or substituted or unsubstituted C2-C20 alkenyl; R1 in formula (B) and formula (D) is the same as R1 in the above formula (II), and will not be repeated here.

[0074] R2, R3, R4 and R5 are each independently hydrogen, a halogen atom, a C1-C20 cyano group, a sulfonic acid group, a C1-C20 sulfonyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C6-C26 aryl group, a substituted or unsubstituted C1-C20 alkoxy group, or a substituted or unsubstituted C6-C26 aryloxy group; R2, R3, R4 and R5 are the same as described above and will not be repeated here.

[0075] The substituents in the substituted C1-C20 alkyl, substituted C2-C20 alkenyl, substituted C6-C26 aryl, substituted C1-C20 alkoxy and substituted C6-C26 aryloxy are independently one or more of halogen atoms, sulfonic acid groups, C1-C20 sulfonyl groups, C6-C26 aryl groups, C1-C20 alkoxy and C6-C26 aryloxy groups, preferably halogen atoms, sulfonic acid groups, C1-C10 sulfonyl groups, It is one or more of C6-C16 aryl groups, C1-C10 alkoxy groups and C6-C16 aryloxy groups, more preferably one or more of halogen atoms, sulfonic acid groups, C1-C5 sulfonyl groups, C6-C10 aryl groups, C1-C5 alkoxy groups and C6-C10 aryloxy groups, and even more preferably one or more of halogen atoms, sulfonic acid groups, C1-C3 sulfonyl groups, C6-C10 aryl groups, C1-C3 alkoxy groups and C6-C10 aryloxy groups.

[0076] Reacting reactant 1 represented by formula (A) or formula (B) with reactant 2 in the presence of a catalyst; the catalyst preferably comprises a palladium catalyst and an iodine salt; the palladium catalyst is preferably Pd-BNP (porous metal particles containing Pd); the iodine salt is preferably potassium iodide (KI); based on active substances, the molar ratio of reactant 1, reactant 2, palladium catalyst and iodine salt is preferably (0.8-1.2):(2-3):((0.1-0.3):(0.9-1.2); in some embodiments provided by the present invention, the molar ratio of reactant 1, reactant 2, palladium catalyst and iodine salt is specifically 1:2.5:0.2:1, 0.9:2:0.1:0.9, 1.2:3:0.3:1.1 or 1:2:0.3:0.9; The reaction is preferably carried out in a solvent; the solvent is an organic solvent well known to those skilled in the art without any particular limitation, and in the present invention, N,N-dimethylformamide (DMF) is preferably used; the reaction temperature is preferably 80°C to 120°C, and more preferably 90°C; the reaction is preferably carried out in an air atmosphere; the reaction time is preferably 30 to 72 hours, and most preferably 36 to 48 hours; in some embodiments provided by the present invention, the reaction time is specifically 48 hours, 36 hours or 72 hours; after the reaction is completed, it is preferably cooled to room temperature, extracted with ethyl acetate, washed with saline solution, and then the solvent is removed and purified by column chromatography to obtain reactant 3; the eluent of the column chromatography is preferably a mixture of hexane and ethyl acetate; the volume ratio of hexane to ethyl acetate is preferably 3:7.

[0077] The reactant 3 is reacted with the reactant 4 to obtain an isoquinolinone additive; the molar ratio of the reactant 3 to the reactant 4 is preferably (0.5-1.5):(2-4); in some embodiments provided by the present invention, the molar ratio of the reactant 3 to the reactant 4 is specifically 1:3, 0.5:2, 1.5:4 or 1.5:3; the reaction is preferably carried out in a protective atmosphere; the protective atmosphere is a protective atmosphere well known to those skilled in the art, and there is no special limitation, and in the present invention, nitrogen is preferably used; the reaction temperature is preferably 50°C-70°C, and more preferably 60°C; The reaction time is preferably 10 to 40 minutes, specifically 10 minutes, 20 minutes, 30 minutes or 40 minutes; after the reaction is completed, it is preferably cooled, extracted with iodomethane, the supernatant is collected, and then extracted with pentane for the second time to obtain an isoquinolinone additive; the cooling is preferably carried out in an ice bath; the cooling time is preferably 10 to 30 minutes, more preferably 15 to 25 minutes, and more preferably 20 minutes; in order to improve the purity of the product, after the pentane secondary extraction, it is preferably distilled to obtain an isoquinolinone additive that can be used as an electrolyte additive.

[0078] The present invention also provides an electrolyte, comprising the above-mentioned isoquinolone additive; the mass of the isoquinolone additive is preferably 1% to 5% of the mass of the electrolyte; in the present invention, specifically, the mass of the isoquinolone additive can be 1%, 2%, 3%, 4% or 5% of the mass of the electrolyte.

[0079] According to the present invention, the electrolyte preferably also includes an organic solvent; the mass of the organic solvent is preferably 60% to 80% of the mass of the electrolyte; the organic solvent is an organic solvent that can be used as an electrolyte solvent and is well known to those skilled in the art, and there is no special restriction. In the present invention, it is preferably one or more of organic esters, ether solvents, sulfone solvents, nitrile solvents and amide solvents; the organic ester is preferably ethylene carbonate (EC), propylene carbonate, butylene carbonate, dimethyl carbonate (DMC), diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, ethyl formate, ethyl acetate, propyl acetate, propyl propionate, γ-butyrolactone, methyl trifluoroethyl carbonate, fluoroethylene carbonate and di(2,2,2-trifluoroethyl) carbonate; the ether solvent is preferably dimethyl ether, diethyl ether, methyl ethyl ether, One or more of ethylene glycol dimethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether and 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether; the sulfone solvent is preferably cyclopentane sulfone; the nitrile solvent is preferably acetonitrile; the amide solvent is preferably 1-methyl-3-ethylcarbonylquinobis(trifluoromethylsulfonyl)imide; in the embodiments provided by the present invention, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate are specifically used as examples for explanation; the mass ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is preferably (0.5-2):(0.5-2):(0.5-2), more preferably (0.5-1.5):(0.5-1.5):(0.5-1.5), more preferably (0.8-1.2):(0.8-1.2):(0.8-1.2), and most preferably 1:1:1.

[0080] According to the present invention, the electrolyte preferably also includes a lithium salt; the mass of the lithium salt is 10% to 18% of the mass of the electrolyte; the lithium salt is a lithium salt that can be used as an electrolyte electrolyte and is well known to those skilled in the art, and there is no special restriction. In the present invention, it is preferably one or more of lithium hexafluorophosphate, lithium perchlorate, lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium bistrifluoromethylsulfonyl imide, lithium bisfluorosulfonyl imide, lithium bisoxalatoborate (LiBOB), lithium difluorooxalatoborate (LiDFOB), lithium difluorobisoxalate phosphate and lithium tetrafluorooxalate phosphate (LiPF4C2O4).

[0081] According to the present invention, the electrolyte preferably also includes a film-forming additive; the mass of the film-forming additive is preferably 1% to 10% of the mass of the electrolyte, more preferably 3% to 10%, more preferably 5% to 10%, and most preferably 8% to 10%; the film-forming additive is preferably one or more of vinylene carbonate (VC), lithium difluorooxalatoborate, vinyl ethylene carbonate (VEC), fluoroethylene carbonate (FEC) and vinyl sulfite (ES).

[0082] The electrolyte provided by the present invention can improve the situation in the prior art where the electrolyte undergoes oxidative decomposition under too high voltage, damaging the battery structure and affecting the cycle performance of the battery, and at the same time improve the safety of the lithium-ion battery.

[0083] The present invention also provides a combined electrolyte for secondary liquid injection, including a first-injected electrolyte, an initiator, and a second-injected electrolyte; the first-injected electrolyte and the second-injected electrolyte are each independently selected from the above-mentioned electrolytes.

[0084] According to the present invention, the mass ratio of the first-injected electrolyte to the second-injected electrolyte is preferably (1-3):(9-7), more preferably (1.5-2.5):(8.5-7.5), and even more preferably 2:8; the compositions of the first-injected electrolyte and the second-injected electrolyte can be the same or different, and there are no special restrictions.

[0085] According to the present invention, the mass of the initiator is preferably 0.1%-0.3% of the mass of the combined electrolyte, and more preferably 0.2%; the initiator can be any initiator well-known to those skilled in the art, and there are no special restrictions. The initiator of the present invention is preferably two types of chemical substances, azo initiators and / or peroxide initiators; the azo initiators are preferably one or more of azodiisobutyronitrile (AIBN) and azodiisopentanenitrile (ABVN); the peroxide initiators are preferably one or more of benzoyl peroxide, tert-butyl benzoyl peroxide, and methyl ethyl ketone peroxide.

[0086] The present invention also provides a method for secondary liquid injection, including the following steps: mixing the first-injected electrolyte and the initiator and injecting them into the lithium-ion battery cell, heating to initiate a polymerization reaction, then injecting the second-injected electrolyte, forming, and grading to obtain a lithium-ion battery.

[0087] The present invention also provides a high-voltage lithium-ion battery, including the above-mentioned electrolyte or the above-mentioned combined electrolyte for secondary liquid injection.

[0088] Specifically, the high-voltage lithium-ion battery includes a positive electrode, a separator, a negative electrode, and the above-mentioned electrolyte or the above-mentioned combined electrolyte for secondary liquid injection.

[0089] More specifically, the positive electrode includes a positive electrode active material; the positive electrode active material is preferably one or more of lithium cobaltate, lithium manganate, nickel cobalt manganese lithium, lithium nickel manganese oxide, lithium iron phosphate, and lithium manganese iron phosphate, more preferably lithium nickel manganese oxide (LNMO), specifically LiNi x Mn 2-x O4, 0<x<1, and more specifically x is 0.5.

[0090] More specifically, the negative electrode includes a negative electrode active material; the negative electrode active material is preferably one or more of artificial graphite, natural graphite, lithium titanate, metallic lithium, silicon-carbon composite material and silicon monoxide, more preferably artificial graphite.

[0091] More specifically, the diaphragm is preferably polypropylene, polyethylene diaphragm, polyethylene diaphragm coated with aluminum oxide on one side, and more preferably polyethylene diaphragm coated with aluminum oxide on one side.

[0092] In order to further illustrate the present invention, an isoquinolinone additive, an electrolyte and a high-voltage lithium-ion battery provided by the present invention are described in detail below in conjunction with examples.

[0093] The reagents used in the following examples are all commercially available.

[0094] Preparation Example 1: Synthesis of the isoquinolinone additive shown in A-1

[0095]

[0096] Step 1: Synthesize carbonylquinone derivative (reactant 3) by reaction, take reactant 1: reactant 2: catalyst 1: catalyst 2 = 1: 2.5: 0.2: 1 (molar mass ratio) and place it in a dry reaction tube equipped with a magnetic ball. Add 20mL DMF to the reaction mixture and stir it in a 90℃ constant temperature device until the reaction is completed. The temperature fluctuation does not exceed ±1℃ and the reaction time is 48h. After the reaction is completed, the reaction mixture is cooled to room temperature and extracted with ethyl acetate. Then the organic phase is dried with Na2SO4 and dried in vacuo. The reaction mixture is purified by silica gel column chromatography, and the eluent volume ratio of hexane: ethyl acetate is 3: 7 to obtain the desired product isocarbonylquinone derivative, i.e. reactant 3.

[0097] The yield of the product isocarbonylquinone derivative (reactant 3) is 69.55% and the purity is 95.39%.

[0098] The mass spectrometry data of reaction product 3 is TOF-MS (ESI) m / z calcd for C 13 H9ClN2O: 244.68; [M+H]+found: 244.04.

[0099] Step 2: Mix the reactants according to the molar mass ratio of reactant 3: reactant 4 = 1:3, transfer to a 50 mL glass tube preheated at 60°C for 10 min, seal the glass tube with a rubber diaphragm, and react in a nitrogen atmosphere for 20 min. Collect the reaction mixture, cool it in an ice bath, stir during the cooling process to promote cooling, and after 20 minutes, slowly extract it with iodomethane, collect the supernatant, and extract the supernatant with pentane for a second time to obtain the reaction product A-1 primary distillation product.

[0100] The final product A-1 has an initial distillation yield of 80.26% and a purity of 90.11%. After distillation, the product purity reaches 99%, and can be used as an electrolyte additive.

[0101] The mass spectrum data of product A-1 is TOF-MS (ESI) m / z calcd for C 16 H 18 N2OSi:282.42;[M+H]+found:282.12.

[0102] Preparation Example 2

[0103] Step 1: Synthesize carbonylquinone derivative (reactant 3) by reaction. According to the molar mass ratio, reactant 1: reactant 2: catalyst 1: catalyst 2 = 0.9: 2: 0.1: 0.9 is placed in a dry reaction tube equipped with a magnetic ball. 20 mL of DMF is added to the reaction mixture, and it is stirred in a 90°C constant temperature device until the reaction is completed. The temperature fluctuation does not exceed ± 1°C, and the reaction time is 36 hours. After the reaction is completed, the reaction mixture is cooled to room temperature, extracted with ethyl acetate, and then the organic phase is dried with Na2SO4 and dried in vacuo. The reaction mixture is purified by silica gel column chromatography, and the volume ratio of the eluent hexane: ethyl acetate is 3: 7 to obtain the desired product isocarbonylquinone derivative, i.e., reactant 3.

[0104] The yield of the product isocarbonylquinone derivative (reactant 3) is close to 55.65% and the purity is 93.66%.

[0105] Step 2: Mix the reactants according to the molar mass ratio of reactant 3: reactant 4 = 0.5:2, transfer to a 50mL glass tube preheated at 50°C for 10 minutes, seal the glass tube with a rubber diaphragm, and react in a nitrogen atmosphere for 10 minutes. Collect the reaction mixture, cool it in an ice bath, stir during the cooling process to promote cooling, and after 10 minutes, slowly extract it with iodomethane, collect the supernatant, and extract the supernatant with pentane for a second time to obtain the reaction product A-1 primary distillation product.

[0106] The final product A-1 has a yield of 65.22% and a purity of 86.65% after initial distillation. After distillation, the purity of the product reaches 99%, and can be used as an electrolyte additive.

[0107] Preparation Example 3

[0108] Step 1: Synthesize carbonylquinone derivative reactant 3 by reaction. According to the molar mass ratio, reactant 1: reactant 2: catalyst 1: catalyst 2 = 1.2: 3: 0.3: 1.1 is placed in a dry reaction tube equipped with a magnetic ball. 20 mL of DMF is added to the reaction mixture, and it is stirred in an open state in a 120°C constant temperature device until the reaction is completed. The temperature fluctuation does not exceed ± 1°C, and the reaction time is 72 hours. After the reaction is completed, the reaction mixture is cooled to room temperature, extracted with ethyl acetate, and then the organic phase is dried with Na2SO4 and dried in vacuo. The reaction mixture is purified by silica gel column chromatography, and the volume ratio of the eluent hexane: ethyl acetate is 3: 7 to obtain the desired product isocarbonylquinone derivative, i.e. reactant 3.

[0109] The yield of the product isocarbonylquinone derivative (reactant 3) is 60.15% and the purity is 88.65%.

[0110] Step 2: Mix the reactants according to the molar mass ratio of reactant 3: reactant 4 = 1.5:4, transfer to a 50mL glass tube preheated at 60°C for 20 minutes, seal the glass tube with a rubber diaphragm, and react in a nitrogen atmosphere for 40 minutes. Collect the reaction mixture, cool it in an ice bath, stir during the cooling process to promote cooling, and after 20 minutes, slowly extract it with iodomethane, collect the supernatant, and extract the supernatant with pentane for a second time to obtain the reaction product A-1 primary distillation product.

[0111] The final product A-1 has a yield of 49.68% after initial distillation and a purity of nearly 81.22%. After distillation, the purity of the product reaches 99% and can be used as an electrolyte additive.

[0112] Preparation Example 4

[0113] Step 1: Synthesize carbonylquinone derivatives by reaction. According to the molar mass ratio, reactant 1: reactant 2: catalyst 1: catalyst 2 = 1: 2: 0.3: 0.9 are placed in a dry reaction tube equipped with a magnetic ball. 20 mL of DMF is added to the reaction mixture, and it is stirred in an open state in a constant temperature device at 80 ° C until the reaction is completed. The temperature fluctuation does not exceed ± 1 ° C, and the reaction time is 48 hours. After the reaction is completed, the reaction mixture is cooled to room temperature, extracted with ethyl acetate, and then the organic phase is dried with Na2SO4 and vacuum dried. The reaction mixture is purified by silica gel column chromatography, and the volume ratio of eluent hexane: ethyl acetate is 3: 7 to obtain the desired product isocarbonylquinone derivative, i.e. reactant 3.

[0114] The yield of the product isocarbonylquinone derivative (reactant 3) is close to 55.36% and the purity is 91.25%.

[0115] Step 2: Mix the reactants according to the molar mass ratio of reactant 3: reactant 4 = 1.5:3, transfer to a 50 mL glass tube preheated at 70°C for 10 min, seal the glass tube with a rubber diaphragm, and react in a nitrogen atmosphere for 20 min. Collect the reaction mixture, cool it in an ice bath, stir during the cooling process to promote cooling, and after 20 minutes, slowly extract it with iodomethane, collect the supernatant, and extract the supernatant with pentane for a second time to obtain the reaction product A-1 primary distillation product.

[0116] The final product A-1 has a yield of approximately 65.39% and a purity of approximately 84.59% after initial distillation. After distillation, the product purity reaches 99%, and can be used as an electrolyte additive.

[0117] Preparation Example 5: Synthesis of the isoquinolinone additive shown in A-2

[0118]

[0119] The preparation method of reaction product A-2 is to feed materials according to the feed ratio of Preparation Example 1, by replacing reactant 2 in step 1 of Preparation Example 1 with reactant 2 in the above reaction formula. The reactants can be purchased directly, and various reaction conditions are similar.

[0120] The mass spectrum data of product A-2 is TOF-MS (ESI) m / z calcdfor C 16 H 15 F3N2OSi:336.39;[M+H]+found:336.09.

[0121] Preparation Example 6: Synthesis of the isoquinolinone additive shown in A-3

[0122]

[0123] The preparation method of reaction product A-3 is to feed materials according to the feed ratio of Preparation Example 1, by replacing reactant 1 in step 1 of Preparation Example 1 with reactant 1 in the above reaction formula. The reactants can be purchased directly, and various reaction conditions are similar.

[0124] Mass spectral data of product A-3TOF-MS(ESI)m / z calcd for C 18 H 15 NO6S:373.38;[M+H]+found:373.06.

[0125] Preparation Example 7: Synthesis of the isoquinolinone additive shown in A-4

[0126]

[0127] The preparation method of reaction product A-4 is to feed the materials according to the feeding ratio of Preparation Example 1, by replacing the reactant 1 in step 1 of Preparation Example 1 with the reactant 1 in the above reaction formula. The reactants can be purchased directly, and the various reaction conditions are similar.

[0128] Mass spectral data of product A-4 TOF-MS (ESI) m / z calcd for C 16 H 17 FN2OSi:300.41;[M+H]+found:300.11.

[0129] Preparation Example 8: Synthesis of the isoquinolinone additive shown in A-5

[0130]

[0131] The preparation method of reaction product A-5 is to feed the materials according to the feeding ratio of Preparation Example 1, by replacing the reactant 4 in step 2 of Preparation Example 1 with the reactant 4 in the above reaction formula. The reactants can be purchased directly, and the various reaction conditions are similar.

[0132] Mass spectral data of product A-5TOF-MS (ESI) m / z calcd for C 17 H 18 N2OSi:294.43;[M+H]+found:294.12.

[0133] Preparation Example 9: Synthesis of the isoquinolinone additive shown in A-6

[0134]

[0135] The preparation method of reaction product A-6 is to feed the materials according to the feeding ratio of Preparation Example 1, by replacing the reactant 1 in step 1 of Preparation Example 1 with the reactant 1 in the above reaction formula. The reactants can be purchased directly, and the various reaction conditions are similar.

[0136] Mass spectral data of product A-6 TOF-MS (ESI) m / z calcd for C 13 H9F3N2OSi:294.31;[M+H]+found:294.04.

[0137] Preparation of lithium-ion battery positive electrode:

[0138] LiNi 0.5 Mn 1.5O4, conductive carbon black, and adhesive (PVDF) were uniformly mixed in a mass ratio of 8:1:1, and a small amount of N-methyl-2-pyrrolidone (NMP) was added and ground and mixed to form a uniform paste, which was then coated on an aluminum foil substrate and dried in a constant temperature device at 100°C to obtain a positive electrode sheet (compacted density 2.42 g / cm 3 ).

[0139] Preparation of lithium-ion battery negative electrode:

[0140] Graphite, conductive carbon black, and adhesive (PVDF) were uniformly mixed in a mass ratio of 8:1:1, and a small amount of N-methyl-2-pyrrolidone (NMP) was added and ground and mixed to form a uniform paste, which was then coated on a copper foil substrate and dried in a constant temperature device at 100°C to obtain a negative electrode sheet (compacted density 1.78 g / cm 3 ).

[0141] Types of separators: The types of lithium battery separators mainly include polyolefin separators, mainly including polyethylene (PE) and polypropylene (PP), etc. The present invention preferably uses a 12 μm PP separator.

[0142] Preparation of LNMO soft pack battery:

[0143] The soft pack was prepared using a soft pack stacking machine. The soft pack had 12 layers of positive electrode and 13 layers of negative electrode. The rated capacity of the soft pack was 2.5Ah and the voltage range of the soft pack was 3.4 to 5V.

[0144] Embodiment 1:

[0145] In a glove box filled with argon (water <1ppm, oxygen <1ppm), ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1:1 to prepare a 1.4 mol / L LiPF6 electrolyte. Finally, 10wt% FEC and 1wt% isoquinolinone additives shown in A-1 were added in sequence, and the lithium ion battery electrolyte of Example 1 was obtained after stirring evenly.

[0146] Embodiment 2:

[0147] In a glove box filled with argon (water <1ppm, oxygen <1ppm), ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1:1 to prepare a 1.4 mol / L LiPF6 electrolyte. Finally, 10wt% FEC and 2wt% isoquinolinone additives shown in A-1 were added in sequence, and the lithium ion battery electrolyte of Example 2 was obtained after stirring evenly.

[0148] Embodiment 3:

[0149] In a glove box filled with argon (water <1ppm, oxygen <1ppm), ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1:1 to prepare a 1.4 mol / L LiPF6 electrolyte. Finally, 10wt% FEC and 3wt% isoquinolinone additives shown in A-1 were added in sequence, and the lithium ion battery electrolyte of Example 3 was obtained after stirring evenly.

[0150] Embodiment 4:

[0151] In a glove box filled with argon (water <1ppm, oxygen <1ppm), ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1:1 to prepare a 1.4 mol / L LiPF6 electrolyte. Finally, 10wt% FEC and 4wt% isoquinolinone additives shown in A-1 were added in sequence, and the lithium ion battery electrolyte of Example 4 was obtained after stirring evenly.

[0152] Embodiment 5:

[0153] In a glove box filled with argon (water <1ppm, oxygen <1ppm), ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1:1 to prepare a 1.4 mol / L LiPF6 electrolyte. Finally, 10wt% FEC and 3wt% isoquinolinone additives shown in A-2 were added in sequence, and the lithium ion battery electrolyte of Example 5 was obtained after stirring evenly.

[0154] Embodiment 6:

[0155] In a glove box filled with argon (water <1ppm, oxygen <1ppm), ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1:1 to prepare a 1.4 mol / L LiPF6 electrolyte. Finally, 10wt% FEC and 3wt% isoquinolinone additives shown in A-3 were added in sequence, and the lithium ion battery electrolyte of Example 6 was obtained after stirring evenly.

[0156] Embodiment 7:

[0157] In a glove box filled with argon (water <1ppm, oxygen <1ppm), ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1:1 to prepare a 1.4 mol / L LiPF6 electrolyte. Finally, 10wt% FEC and 3wt% isoquinolinone additives shown in A-4 were added in sequence, and the lithium ion battery electrolyte of Example 7 was obtained after stirring evenly.

[0158] Embodiment 8:

[0159] In a glove box filled with argon (water <1ppm, oxygen <1ppm), ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1:1 to prepare a 1.4 mol / L LiPF6 electrolyte. Finally, 10wt% FEC and 3wt% isoquinolinone additives shown in A-5 were added in sequence, and the lithium ion battery electrolyte of Example 8 was obtained after stirring evenly.

[0160] Embodiment 9:

[0161] In a glove box filled with argon (water <1ppm, oxygen <1ppm), ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1:1 to prepare a 1.4 mol / L LiPF6 electrolyte. Finally, 10wt% FEC and 3wt% isoquinolinone additives shown in A-6 were added in sequence, and the lithium ion battery electrolyte of Example 9 was obtained after stirring evenly.

[0162] Comparative Example 1:

[0163] In a glove box filled with argon (water <1ppm, oxygen <1ppm), ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1:1 to prepare a 1.4 mol / L LiPF6 electrolyte. Finally, 14 wt% FEC was added in sequence and stirred evenly to obtain the lithium ion battery electrolyte of Comparative Example 1.

[0164] Comparative Example 2:

[0165] In a glove box filled with argon (water <1ppm, oxygen <1ppm), ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1:1 to prepare a 1.4 mol / L LiPF6 electrolyte. Finally, 10wt% FEC and 3wt% molecular formula B were added in sequence, and the lithium ion battery electrolyte of Comparative Example 2 was obtained after stirring evenly.

[0166]

[0167] Table 1 Electrolyte formula

[0168] Electrolyte group Formula (mass fraction) Example 1 <![CDATA[LiPF6:EC:DMC:DEC:FEC:A-1=18:23.7:23.7:23.7:10:1]]> Example 2 <![CDATA[LiPF6:EC:DMC:DEC:FEC:A-1=18:23.3:23.3:23.3:10:2]]> Example 3 <![CDATA[LiPF6:EC:DMC:DEC:FEC:A-1=18:23:23:23:10:3]]> Example 4 <![CDATA[LiPF6:EC:DMC:DEC:FEC:A-1=18:22.7:22.7:22.7:10:4]]> Example 5 <![CDATA[LiPF6:EC:DMC:DEC:FEC:A-2=18:23:23:23:10:3]]> Example 6 <![CDATA[LiPF6:EC:DMC:DEC:FEC:A-3=18:23:23:23:10:3]]> Example 7 <![CDATA[LiPF6:EC:DMC:DEC:FEC:A-4=18:23:23:23:10:3]]> Example 8 <![CDATA[LiPF6:EC:DMC:DEC:FEC:A-5=18:23:23:23:10:3]]> Example 9 <![CDATA[LiPF6:EC:DMC:DEC:FEC:A-6=18:23:23:23:10:3]]> Comparative Example 1 <![CDATA[LiPF6:EC:DMC:DEC:FEC:A-1=18:24:24:24:14:0]]> Comparative Example 2 <![CDATA[LiPF6:EC:DMC:DEC:FEC:B=18:23:23:23:10:3]]>

[0169] Table 2 HOMO and LUMO of different additives

[0170]

[0171]

[0172] Electrolyte oxidation potential test method:

[0173] The electrolytic cell device was assembled to test the LSV data. The three-electrode system consisted of a glassy carbon electrode as a working electrode, a stainless steel electrode holding a lithium sheet as a counter electrode and a reference electrode. The amount of electrolyte only covered the stainless steel electrode holding the lithium sheet and did not exceed the lower end of the stainless steel electrode. The test voltage range was from open circuit voltage to 8V. The oxidation decomposition potential of the various additive molecules provided by the present invention was tested. The test results are as follows: Figure 1 shown.

[0174] according to Figure 1 The test results show that the oxidative decomposition potentials of A-1 to A-6 are significantly lower than those of other groups of additive molecules. This result also corresponds to the HOMO / LUMO energy levels of various additive molecules.

[0175] According to experimental data, it can be found that the oxidative decomposition potential window of carbonate electrolytes is mainly concentrated in the range of 5.0V to 5.5V, while the cyanocarbonylquinone substances proposed in the present invention will decompose in advance in the voltage range of 4.2 to 4.7V, and can form a CEI film on the surface of the positive electrode material, thereby reducing the decomposition process of the electrolyte on the positive electrode surface.

[0176] According to the experimental results, the LSV data showed that there were two oxidation decomposition peaks in the voltage range of 4.1 to 4.4 V. It is speculated that the decomposition peak with a lower decomposition voltage is the decomposition peak of cyanide, and the decomposition peak with a higher decomposition voltage is the decomposition peak of carbonylquinone. The unsaturation of the CN triple bond is higher than that of the CN double bond of carbonylquinone, so it will decompose preferentially to form a highly stable CEI film on the surface of the positive electrode.

[0177] Based on the above electrolyte electrolytic cell test data, it is speculated that cyanocarbonylquinone additives may have relatively excellent performance in the 5VLNMO / AG system. Therefore, electrical performance tests were carried out using soft packs with a rated capacity of 2.5Ah and LNMO for artificial graphite system. Both LNMO and AG are currently commercialized positive and negative electrode materials that can be purchased in large quantities. The electrolyte used is the company's own electrolyte, and various additives can also be purchased commercially.

[0178] The soft pack battery test is carried out using a Xinwei 5V6A tester, and the test process is carried out in a constant temperature room at 25°C. The soft pack injection process includes two injections in the formation stage, one injection of 20% electrolyte, and 0.2% initiator is mixed in it. The initiator is azobisisobutyronitrile (AIBN). The amount of initiator is calculated. After the polymerization is initiated, the remaining electrolyte is continued to be injected, and no secondary polymerization will be initiated. The total amount of the two injections of electrolyte is 80%. After the first injection is completed, the soft pack is placed in a 50°C oven for 24 hours to initiate polymerization. After the second injection is completed, the formation operation is carried out, the formation is completed, and the volume is divided.

[0179] The battery is formed according to the following steps: 0.1C constant current charging to 3.0V, 0.2C constant current charging to 3.3V, the formed battery is first aged, then vacuum sealed, and then capacity divided according to the following steps: 0.5C constant current discharge to 2.5V, 0.5C constant current constant voltage charging to 3.65V, constant current discharge to 2.5V, cross-current charging to 3.3V, first effect = (constant current discharge total capacity / constant current constant voltage charging capacity + formation charging capacity) × 100%.

[0180] The results are as follows. The main data include the first effect of the soft pack, the fractional capacity, and the capacity retention rate at room temperature, 1C, and 100 cycles. The three sets of data are shown in Table 3.

[0181] Table 3 Soft pack test data

[0182] First effect / % Capacity / Ah 1C, RT, 1000Clys / % Example 1 87.34％ 2.1437 69.78％ Example 2 88.54％ 2.1654 71.44％ Example 3 81.22％ 2.2275 75.46％ Example 4 85.43％ 2.2109 63.78％ Example 5 86.26％ 2.1978 68.65％ Example 6 83.08％ 2.1765 60.88％ Example 7 84.87％ 2.1628 63.09％ Example 8 81.56％ 2.1543 61.45％ Example 9 82.24％ 2.1633 65.34％ Comparative Example 1 59.88％ 2.0154 37.77％ Comparative Example 2 70.23％ 2.1132 48.55％

[0183] According to the experimental results, it can be found that the electrochemical effect of molecular formula A is currently the best, and the electrochemical performance effect of 1% addition is also better than the electrochemical performance effect of 5% addition of other types of additives.

[0184] By comparing Examples 1 to 4, it is found that the electrochemical performance of the molecular formula A with an addition amount of 5% is the best, and by comparing Example 3 with Examples 5, 6, 7, and 8, it can be seen that the performance of the molecular formula A is better than that of the other additive molecules, but the embodiments of the other additive molecules are better than the comparative examples. Therefore, it can be concluded that the trimethylsilyl-substituted cyanocarbonylquinone has a significant effect on the LNMO / AG system with a voltage of 5V, and it is verified by experiments that the performance of the molecular formula A is better than that of the cyanocarbonylquinone additive with other substituents.

[0185] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. An isoquinolinone additive, characterized in that: Having a structure shown in formula (I) or formula (II): Wherein, R1, R2, R3, R4 and R5 in formula (I) and formula (III) are independently selected from hydrogen, halogen atoms, C1-C20 cyano groups, sulfonic acid groups, C1-C20 sulfonyl groups, substituted or unsubstituted C1-C20 alkyl groups, substituted or unsubstituted C2-C20 alkenyl groups, substituted or unsubstituted C6-C26 aryl groups, substituted or unsubstituted C1-C20 alkoxy groups, substituted or unsubstituted C6-C26 aryloxy groups; In formula (II), R1 is selected from C1-C20 cyano, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl; In formula (II), R2, R3, R4 and R5 are each independently selected from hydrogen, a halogen atom, a C1-C20 cyano group, a sulfonic acid group, a C1-C20 sulfonyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C6-C26 aryl group, a substituted or unsubstituted C1-C20 alkoxy group, or a substituted or unsubstituted C6-C26 aryloxy group; The substituents in the substituted C1-C20 alkyl, substituted C2-C20 alkenyl, substituted C6-C26 aryl, substituted C1-C20 alkoxy and substituted C6-C26 aryloxy are independently selected from one or more of halogen atoms, sulfonic acid groups, C1-C20 sulfonyl groups, C6-C26 aryl groups, C1-C20 alkoxy and C6-C26 aryloxy groups.

2. The isoquinolinone additive according to claim 1, characterized in that: In formula (I) and formula (III), R1, R2, R3, R4 and R5 are each independently selected from hydrogen, a halogen atom, a C1-C10 cyano group, a sulfonic acid group, a C1-C10 sulfonyl group, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C2-C10 alkenyl group, a substituted or unsubstituted C6-C10 aryl group, a substituted or unsubstituted C1-C10 alkoxy group, or a substituted or unsubstituted C6-C10 aryloxy group; In formula (II), R1 is selected from C1-C10 cyano, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C2-C10 alkenyl; In formula (II), R2, R3, R4 and R5 are each independently selected from hydrogen, a halogen atom, a C1-C10 cyano group, a sulfonic acid group, a C1-C10 sulfonyl group, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C2-C10 alkenyl group, a substituted or unsubstituted C6-C10 aryl group, a substituted or unsubstituted C1-C10 alkoxy group, or a substituted or unsubstituted C6-C10 aryloxy group; The substituents in the substituted C1-C10 alkyl, substituted C2-C10 alkenyl, substituted C6-C10 aryl, substituted C1-C10 alkoxy and substituted C6-C10 aryloxy are each independently selected from halogen atoms.

3. The isoquinolinone additive according to claim 1, characterized in that: The film-forming additive is selected from one or more of A-1 to A-6; 4. A method for preparing an isoquinolinone additive, characterized in that: The following steps are involved: S1) reacting reactant 1 represented by formula (A) or formula (B) with reactant 2 in the presence of a catalyst to obtain reactant 3 represented by formula (C) or formula (D); S2) reacting the reactant 3 with the reactant 4 to obtain an isoquinolinone additive; X is a halogen atom; In formula (A) and formula (C), R1 is selected from hydrogen, halogen atom, C1-C20 cyano group, sulfonic acid group, C1-C20 sulfonyl group, substituted or unsubstituted C1-C20 alkyl group, substituted or unsubstituted C2-C20 alkenyl group, substituted or unsubstituted C6-C26 aryl group, substituted or unsubstituted C1-C20 alkoxy group, substituted or unsubstituted C6-C26 aryloxy group; In formula (B) and formula (D), R1 is selected from C1-C20 cyano, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl; R2, R3, R4 and R5 are each independently selected from hydrogen, a halogen atom, a C1-C20 cyano group, a sulfonic acid group, a C1-C20 sulfonyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C6-C26 aryl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C6-C26 aryloxy group; The substituents in the substituted C1-C20 alkyl, substituted C2-C20 alkenyl, substituted C6-C26 aryl, substituted C1-C20 alkoxy and substituted C6-C26 aryloxy are independently selected from one or more of halogen atoms, sulfonic acid groups, C1-C20 sulfonyl groups, C6-C26 aryl groups, C1-C20 alkoxy and C6-C26 aryloxy groups.

5. The preparation method according to claim 4, characterized in that: The catalyst comprises a palladium catalyst and an iodine salt; the molar ratio of the reactant 1, the reactant 2, the palladium catalyst and the iodine salt is (0.8-1.2):(2-3):((0.1-0.3):(0.9-1.2); And / or, the reaction temperature in step S1) is 80°C to 120°C.

6. An electrolyte, characterized in that: The invention comprises the isoquinolone additive according to any one of claims 1 to 3 or the isoquinolone additive prepared by the preparation method according to claim 4 or 5.

7. The electrolyte according to claim 6, characterized in that The mass of the isoquinolinone additive is 1% to 5% of the mass of the electrolyte; And / or, the electrolyte further comprises an organic solvent, a lithium salt and a film-forming additive; The mass of the organic solvent is 60% to 80% of the mass of the electrolyte; The mass of the lithium salt is 10% to 18% of the mass of the electrolyte; The mass of the film-forming additive is 1% to 10% of the mass of the electrolyte.

8. The electrolyte according to claim 7, characterized in that The organic solvent is selected from one or more of organic esters, ether solvents, sulfone solvents, nitrile solvents and amide solvents; the organic ester is selected from ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethyl formate, ethyl acetate, propyl acetate, propyl propionate, γ-butyrolactone, methyl trifluoroethyl carbonate, fluoroethylene carbonate and di(2,2,2-trifluoroethyl)carbonate. The ether solvent is selected from one or more of dimethyl ether, diethyl ether, methyl ethyl ether, ethylene glycol dimethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether and 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether; the sulfone solvent is selected from sulfolane; the nitrile solvent is selected from acetonitrile; the amide solvent is selected from 1-methyl-3-ethylcarbonylquinonebis(trifluoromethylsulfonyl)imide; And / or, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium bis(trifluoromethylsulfonyl imide), lithium bis(fluorosulfonyl imide), lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium difluorobis(oxalatophosphate) and lithium tetrafluorooxalatophosphate; And / or, the film-forming additive is selected from one or more of vinylene carbonate, lithium difluorooxalatoborate, vinyl ethylene carbonate, fluoroethylene carbonate and vinyl sulfite.

9. A combined electrolyte for secondary injection, characterized in that: It includes a first injection electrolyte, an initiator and a second injection electrolyte; The first injection electrolyte and the second injection electrolyte are each independently selected from the electrolyte described in any one of claims 6 to 8.

10. A high voltage lithium ion battery, characterized in that: A combined electrolyte comprising the electrolyte described in any one of claims 6 to 8 or the secondary injection electrolyte described in claim 9.

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