CN118281326A - Nonaqueous electrolyte and secondary battery - Google Patents

Nonaqueous electrolyte and secondary battery Download PDF

Info

Publication number
CN118281326A
CN118281326A CN202310749531.XA CN202310749531A CN118281326A CN 118281326 A CN118281326 A CN 118281326A CN 202310749531 A CN202310749531 A CN 202310749531A CN 118281326 A CN118281326 A CN 118281326A
Authority
CN
China
Prior art keywords
additive
group
phosphate
battery
dipropylethyl
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202310749531.XA
Other languages
Chinese (zh)
Inventor
胡时光
向晓霞
陈炜麟
林雄贵
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shenzhen Capchem Technology Co Ltd
Original Assignee
Shenzhen Capchem Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shenzhen Capchem Technology Co Ltd filed Critical Shenzhen Capchem Technology Co Ltd
Publication of CN118281326A publication Critical patent/CN118281326A/en
Pending legal-status Critical Current

Links

Classifications

    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Landscapes

  • Secondary Cells (AREA)

Abstract

In order to overcome the problems of insufficient high-temperature storage and high-temperature cycle performance of the existing lithium ion battery, the invention provides a non-aqueous electrolyte, which comprises a solvent, electrolyte salt and an additive, wherein the additive comprises an additive A and an additive B, and the additive A comprises the following components in percentage by weight: the additive A is selected from compounds shown in a structural formula I: the additive B is obtained by bonding a compound shown in a structural formula II with at least one of a group A or a group B: wherein in the structural formula II, an oxygen atom of a hydroxyl group is bonded with one or two of the group A and the group B, and the bonding position is represented;

Description

Nonaqueous electrolyte and secondary battery
Technical Field
The invention belongs to the technical field of batteries, and particularly relates to a nonaqueous electrolyte and a secondary battery.
Background
The lithium ion battery has the advantages of high working voltage, wide working temperature range, high energy density, no memory effect, long cycle life and the like, and is widely applied to the fields of digital consumer electronic products and new energy automobiles. In recent years, both digital batteries and power batteries tend to develop in the direction of high energy density, and in the aspect of ternary positive electrode materials commonly used in power, the development mainly tends to develop in the direction of high nickel content and high voltage, and the problem of unstable interface of the ternary positive electrode is brought about, so that a series of problems such as side reaction of electrolyte, gas production, dissolution of metal ions and the like are caused, and the performance of the battery is deteriorated.
At present, on the aspect of electrolyte, the quality of an SEI film is generally improved by adding different negative electrode film forming additives (such as vinylene carbonate, fluoroethylene carbonate, ethylene carbonate, phosphate compounds and the like), so as to solve the problems. Phosphate compounds, particularly unsaturated phosphate, serving as an anode film-forming additive can form passivation films on the surfaces of the anode and the cathode, so that the high-temperature storage performance and the cycle performance of the battery are improved, but the improvement of the high-temperature storage performance and the cycle performance is limited, and the application of the unsaturated phosphate alone as an additive of an electrolyte can not meet the market use requirement.
Disclosure of Invention
Aiming at the problems of insufficient high-temperature storage and high-temperature cycle performance of the existing lithium ion battery, the invention provides a non-aqueous electrolyte and a secondary battery.
The technical scheme adopted by the invention for solving the technical problems is as follows:
in one aspect, the present invention provides a nonaqueous electrolyte comprising a solvent, an electrolyte salt, and an additive comprising an additive a and an additive B, wherein:
the additive A is selected from compounds shown in a structural formula I:
Wherein R 6、R7、R8 is independently selected from C1-C5 alkyl or haloalkyl, C2-C5 unsaturated hydrocarbon or unsaturated halogenated hydrocarbon, and at least one of R 6、R7、R8 is unsaturated hydrocarbon or unsaturated halogenated hydrocarbon;
the additive B is obtained by bonding a compound shown in a structural formula II with at least one of a group A or a group B:
Wherein n is 0 or 1; r 1、R2、R3、R4、R5 is independently selected from an alkoxy group of H, C 1～C5, a hydroxyl group or an alkyl group containing a hydroxyl group and having a carbon number of C 1～C5, and R 1～R5 contains at least 4 hydroxyl groups;
wherein in the structural formula II, an oxygen atom of a hydroxyl group is bonded with one or two of the group A and the group B, and the bonding position is represented;
Optionally, in the additive B, the compound shown in the structural formula II contains at least 4 hydroxyl groups bonded with one or two of the groups A and B, and forms at least 2 cyclic structures containing one or two of the groups A and B.
Optionally, the additive B is selected from at least one of the following compounds:
Alternatively, the C1-C5 alkyl is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl or neopentyl; a C1-C5 haloalkyl group selected from the group consisting of a halogen substituted for one or more hydrogen elements in said C1-C5 alkyl group; the unsaturated hydrocarbon group of C2-C5 is selected from ethenyl, propenyl, allyl, butenyl, pentenyl, methylvinyl, methallyl, ethynyl, propynyl, propargyl, butynyl or pentynyl, and the unsaturated halogenated hydrocarbon group of C2-C5 is selected from the group obtained by substituting one or more hydrogen elements in the unsaturated hydrocarbon group of C2-C5 with halogen.
Optionally, the additive a is selected from at least one of the following compounds:
At least one of tripropylethyl phosphate, dipropylethyl methyl phosphate, dipropylethyl ethyl phosphate, dipropylethyl propyl phosphate, dipropylethyl trifluoromethyl phosphate, dipropylethyl-2, 2-trifluoroethyl phosphate, dipropylethyl-3, 3-trifluoropropyl phosphate, dipropylethyl hexafluoroisopropyl phosphate, triallyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl-2, 2-trifluoroethyl phosphate, diallyl-3, 3-trifluoropropyl phosphate, diallyl hexafluoroisopropyl phosphate.
Optionally, the mass percentage of the additive A is 0.01% -5% and the mass percentage of the additive B is 0.01% -10% based on 100% of the total mass of the nonaqueous electrolyte.
Optionally, the electrolyte salt is selected from lithium salts selected from at least one of LiPF6、LiBOB、LiDFOB、LiPO2F2、LiBF4、LiSbF6、LiAsF6、LiN(SO2CF3)2、LiN(SO2C2F5)2、LiC(SO2CF3)3、LiN(SO2F)2、LiClO4、LiAlCl4、LiSO3F、LiCF3SO3、Li2B10Cl10、 lower aliphatic carboxylic acid lithium salts.
Optionally, the concentration of the lithium salt is 0.1mol/L to 8mol/L.
Optionally, the solvent includes at least one of an ether solvent, a nitrile solvent, a carbonate solvent, a carboxylate solvent, and a sulfone solvent.
In another aspect, the present invention provides a secondary battery comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte as described above.
Optionally, the secondary battery is a lithium metal battery, a lithium ion battery or a lithium sulfur battery.
According to the non-aqueous electrolyte provided by the invention, the additive A and the additive B are adopted as a film forming additive combination, the additive A and the additive B can cooperatively participate in the formation of a cathode surface SEI film and an anode surface CEI film, wherein the unsaturated hydrocarbon group in the additive A can be polymerized on the cathode surface to form a phosphorus-containing SEI film in a formation stage, after the additive A is reduced, free radicals generated by P-O fracture are diffused to the surface of a positive plate to be oxidized, the CEI film can be formed on the anode surface, the problem of insufficient thermal stability exists in the film formation of the additive A is solved, the additive B is additionally added, a better reinforcing effect is achieved, the additive B has a cyclic ether and sulfate/sulfite structure, electrons can be obtained in the surfaces of a cathode material layer and an anode material layer to form a conductive interface containing lithium sulfate, and sulfate/sulfite units in the structure can be respectively subjected to homolysis to form free radicals, and further be integrated with the phosphorus-containing film and the CEI film to form stable and crosslinked membranes, and finally the battery has excellent electrochemical storage stability under high-temperature conditions.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects solved by the invention more clear, the invention is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The embodiment of the invention provides a non-aqueous electrolyte, which comprises a solvent, electrolyte salt and an additive, wherein the additive comprises an additive A and an additive B, and the additive A comprises the following components:
the additive A is selected from compounds shown in a structural formula I:
Wherein R 6、R7、R8 is independently selected from C1-C5 alkyl or haloalkyl, C2-C5 unsaturated hydrocarbon or unsaturated halogenated hydrocarbon, and at least one of R 6、R7、R8 is unsaturated hydrocarbon or unsaturated halogenated hydrocarbon;
the additive B is obtained by bonding a compound shown in a structural formula II with at least one of a group A or a group B:
Wherein n is 0 or 1; r 1、R2、R3、R4、R5 is independently selected from an alkoxy group of H, C 1～C5, a hydroxyl group or an alkyl group containing a hydroxyl group and having a carbon number of C 1～C5, and R 1～R5 contains at least 4 hydroxyl groups;
wherein in the structural formula II, an oxygen atom of a hydroxyl group is bonded with one or two of the group A and the group B, and the bonding position is represented;
Specifically, in the structural formula II, R 1、R2、R3、R4、R5 may be the same or different, and the application is not limited, and it is noted that R 1、R2、R3、R4、R5 must contain at least 4 hydroxyl functional groups. In the structural formula II, the oxygen atom of the hydroxyl group is bonded with one or two groups A and B, namely the structural formula II can be bonded with two identical groups A or two identical groups B, or can be bonded with one group A and one group B to form a functional additive of sulfate or sulfite with a five-membered ring structure or a functional additive of sulfate or sulfite with a six-membered ring structure.
According to the non-aqueous electrolyte provided by the invention, the additive A and the additive B are adopted as a film forming additive combination, the additive A and the additive B can cooperatively participate in the formation of a cathode surface SEI film and an anode surface CEI film, wherein the unsaturated hydrocarbon group in the additive A can be polymerized on the cathode surface to form a phosphorus-containing SEI film in a formation stage, after the additive A is reduced, free radicals generated by P-O fracture are diffused to the surface of a positive plate to be oxidized, the CEI film can be formed on the anode surface, the problem of insufficient thermal stability exists in the film formation of the additive A is solved, the additive B is additionally added, a better reinforcing effect is achieved, the additive B has a cyclic ether and sulfate/sulfite structure, electrons can be obtained in the surfaces of a cathode material layer and an anode material layer to form a conductive interface containing lithium sulfate, and sulfate/sulfite units in the structure can be respectively subjected to homolysis to form free radicals, and further be integrated with the phosphorus-containing film and the CEI film to form stable and crosslinked membranes, and finally the battery has excellent electrochemical storage stability under high-temperature conditions.
In some embodiments, the additive B comprises at least 4 hydroxyl groups bonded to one or both of group A and group B, and at least 2 cyclic structures comprising one or both of group A and group B are formed.
In some embodiments, the additive B is selected from at least one of the following compounds:
the above is only a preferred compound of the present invention, and does not represent a limitation of the present invention.
The person skilled in the art, knowing the structural formula of additive B, can know the method of preparation of additive B according to common general knowledge in the field of chemical synthesis. For example:
Compound 1 arabinogany disulfite can be prepared by the following method: arabinose, ethyl acetate and pyridine are placed in a reaction vessel, and thionyl chloride is added dropwise under the condition of low temperature. After reacting for several hours, filtering, washing the filtrate with saturated saline solution, separating liquid, drying the organic phase with anhydrous magnesium sulfate, carrying out suction filtration, and concentrating under reduced pressure to obtain the compound 1 arabinose disulfite.
Compound 2 arabinose disulfate can be prepared by the following method: the compound 2 arabinose disulfate is obtained by oxidizing sulfite by using oxidant such as sodium hypochlorite after the compound 1 arabinose disulfate is prepared by a preparation method of the compound 1 arabinose disulfate.
In some embodiments, the C1-C5 alkyl is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, or neopentyl; a C1-C5 haloalkyl group selected from the group consisting of a halogen substituted for one or more hydrogen elements in said C1-C5 alkyl group; the unsaturated hydrocarbon group of C2-C5 is selected from ethenyl, propenyl, allyl, butenyl, pentenyl, methylvinyl, methallyl, ethynyl, propynyl, propargyl, butynyl or pentynyl, and the unsaturated halogenated hydrocarbon group of C2-C5 is selected from the group obtained by substituting one or more hydrogen elements in the unsaturated hydrocarbon group of C2-C5 with halogen.
In some embodiments, the additive a is selected from at least one of the following compounds:
At least one of tripropylethyl phosphate, dipropylethyl methyl phosphate, dipropylethyl ethyl phosphate, dipropylethyl propyl phosphate, dipropylethyl trifluoromethyl phosphate, dipropylethyl-2, 2-trifluoroethyl phosphate, dipropylethyl-3, 3-trifluoropropyl phosphate, dipropylethyl hexafluoroisopropyl phosphate, triallyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl-2, 2-trifluoroethyl phosphate, diallyl-3, 3-trifluoropropyl phosphate, diallyl hexafluoroisopropyl phosphate.
The above is only a preferred compound of the present invention, and does not represent a limitation of the present invention.
In some embodiments, the additive A is 0.01-5% by mass and the additive B is 0.01-10% by mass, based on 100% by mass of the total nonaqueous electrolyte.
In specific embodiments, the additive a may be 0.01%, 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5% or 5% by mass based on 100% by mass of the total nonaqueous electrolyte.
In a specific embodiment, the mass percentage of the additive B may be 0.01％、0.05％、0.08％、0.1％、0.5％、0.8％、1％、1.2％、1.5％、1.8％、2％、2.2％、2.5％、2.8％、3％、3.2％、3.5％、3.8％、4％、4.5％、5％、5.5％、6％、6.5％、7％、7.5％、7.8％、8％、8.5％、9％、9.5％ or 10% based on 100% of the total mass of the nonaqueous electrolytic solution.
In a preferred embodiment, the mass percentage of the additive A is 0.01% -3% and the mass percentage of the additive B is 0.01% -5% based on 100% of the total mass of the nonaqueous electrolyte.
In the nonaqueous electrolyte, the addition amount of the additive a and the addition amount of the additive B are related to the film formation quality, and when the addition amount of either the additive a or the additive B is too low, the film formation thickness of the interfacial film is not uniform, and there is a problem that the stability is poor, the effect of better improving the high temperature performance is difficult to achieve, whereas when the addition amount of either the additive a or the additive B is too high, the side reaction in the nonaqueous electrolyte is increased, the film formation thickness of the interfacial film is increased, and the battery impedance is increased.
In various embodiments, the corresponding electrolyte salt may be selected according to the type of battery applied, and in particular, when the nonaqueous electrolyte solution is applied to a lithium ion battery, the electrolyte salt is selected from lithium salts.
In some embodiments, the electrolyte salt comprises a lithium salt selected from at least one of the lithium salts of LiPF6、LiBOB、LiDFOB、LiPO2F2、LiBF4、LiSbF6、LiAsF6、LiN(SO2CF3)2、LiN(SO2C2F5)2、LiC(SO2CF3)3、LiN(SO2F)2、LiClO4、LiAlCl4、LiSO3F、LiCF3SO3、Li2B10Cl10、 lower aliphatic carboxylic acids.
The electrolyte salt in the nonaqueous electrolyte solution is dissociated to form alkali metal ions which are deintercalated and embedded between the positive electrode and the negative electrode to complete charge and discharge circulation, the concentration of the electrolyte salt directly influences the transmission speed of the alkali metal ions, and the transmission speed of the alkali metal ions influences the potential change of the negative electrode. In the process of quick battery charging, the moving speed of alkali metal ions needs to be improved as much as possible, the formation of lithium dendrites caused by too fast negative electrode potential drop is prevented, potential safety hazards are brought to the battery, and meanwhile, the too fast attenuation of the circulating capacity of the battery can be prevented. When the content of the electrolyte salt is too low, the intercalation and deintercalation efficiency of alkali metal ions between the positive electrode and the negative electrode can be reduced, and the requirement of quick charge of the battery can not be met; when the content of the electrolyte salt is too high, the viscosity of the nonaqueous electrolyte is increased, and thus the improvement of the intercalation and deintercalation efficiency of alkali metal ions is also unfavorable, and the internal resistance of the battery is increased.
When the electrolyte salt includes a lithium salt, the concentration of the lithium salt is 0.1mol/L to 8mol/L.
In a preferred embodiment, the concentration of the lithium salt is 0.5mol/L to 2.5mol/L. Specifically, the concentration of the electrolyte salt may be 0.5mol/L、1mol/L、1.1mol/L、1.5mol/L、2mol/L、2.5mol/L、3mol/L、3.5mol/L、4mol/L、4.5mol/L、5mol/L、5.5mol/L、6mol/L、6.5mol/L、7mol/L、7.5mol/L、8mol/L.
In some embodiments, the non-aqueous organic solvent comprises at least one of an ether solvent, a nitrile solvent, a carbonate solvent, a carboxylate solvent, and a sulfone solvent.
In some embodiments, the ether solvent includes a cyclic ether or a chain ether, preferably a chain ether having 3 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms, and the cyclic ether may specifically be at least one of 1, 3-Dioxolane (DOL), 1, 4-Dioxane (DX), crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH 3 -THF), 2-trifluoromethyl tetrahydrofuran (2-CF 3 -THF), but not limited thereto; the chain ether may be, but not limited to, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether. Since the chain ether has high solvation ability with lithium ions and can improve ion dissociation properties, dimethoxymethane, diethoxymethane and ethoxymethoxymethane, which have low viscosity and can impart high ion conductivity, are particularly preferable. The ether compound may be used alone, or two or more of them may be used in any combination and ratio. The amount of the ether compound to be added is not particularly limited, and is arbitrary within a range that does not significantly impair the effect of the high-pressure lithium ion battery of the present invention.
In some embodiments, the nitrile solvent may be, but is not limited to, at least one of acetonitrile, glutaronitrile, malononitrile.
In some embodiments, the carbonate-based solvent includes a cyclic carbonate or a chain carbonate, which may be specifically but not limited to at least one of Ethylene Carbonate (EC), propylene Carbonate (PC), gamma-butyrolactone (GBL), butylene Carbonate (BC); the chain carbonate may be, but not limited to, at least one of dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), dipropyl carbonate (DPC). The content of the cyclic carbonate is not particularly limited and is arbitrary within a range that does not significantly impair the effect of the lithium ion battery of the present invention.
In some embodiments, it may also be preferable to use a chain carbonate having a fluorine atom (hereinafter simply referred to as "fluorinated chain carbonate"). The number of fluorine atoms in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less. In the case where the fluorinated chain carbonate has a plurality of fluorine atoms, these fluorine atoms may be bonded to the same carbon or may be bonded to different carbons. Examples of the fluorinated chain carbonate include fluorinated dimethyl carbonate derivatives, fluorinated ethyl methyl carbonate derivatives, and fluorinated diethyl carbonate derivatives.
The carboxylic acid ester solvent includes a cyclic carboxylic acid ester and/or a chain carbonate. Examples of the cyclic carboxylic acid ester include: at least one of gamma-butyrolactone, gamma-valerolactone and delta-valerolactone. Examples of the chain carbonate include, for example: at least one of Methyl Acetate (MA), ethyl Acetate (EA), propyl acetate (EP), butyl acetate, propyl Propionate (PP) and butyl propionate.
In some embodiments, the sulfone-based solvent includes cyclic sulfones and chain sulfones, preferably compounds having generally 3 to 6 carbon atoms, preferably 3 to 5 carbon atoms in the case of cyclic sulfones, and generally 2 to 6 carbon atoms, preferably 2 to 5 carbon atoms in the case of chain sulfones. The amount of the sulfone-based solvent to be added is not particularly limited and is arbitrary within a range that does not significantly impair the effect of the lithium ion battery of the present invention.
In a preferred embodiment, the solvent is a mixture of cyclic carbonates and chain carbonates.
Another embodiment of the present invention provides a secondary battery including a positive electrode, a negative electrode, and a nonaqueous electrolytic solution as described above.
The secondary battery adopts the non-aqueous electrolyte, so that an interface film which is uniform and stable and has better strength and toughness can be formed at an electrode interface, and the high-temperature storage and cycle performance of the secondary battery are obviously improved.
In specific embodiments, the secondary battery is a lithium metal battery, a lithium ion battery, a lithium sulfur battery, or the like.
In some embodiments, the positive electrode includes a positive electrode material layer including a positive electrode active material, and the kind and content of the positive electrode active material are not particularly limited, and may be selected according to actual needs, as long as it is a positive electrode active material or a conversion type positive electrode material capable of reversibly intercalating/deintercalating metal ions (lithium ions, etc.).
In a preferred embodiment, the secondary battery is a lithium ion battery, the positive electrode active material of which may be selected from at least one of LiFe 1-x'M'x'PO4、LiMn2-y'My'O4 and LiNi xCoyMnzM1-x-y-zO2, wherein M ' is selected from at least one of Mn, mg, co, ni, cu, zn, al, sn, B, ga, cr, sr, zr, W, V or Ti, M is selected from at least one of Fe, co, ni, mn, mg, cu, zn, al, sn, B, ga, cr, sr, zr, W, V or Ti, and 0.ltoreq.x ' < 1, 0.ltoreq.y '. Ltoreq.1, 0.ltoreq.y.ltoreq.1, 0.ltoreq.x.ltoreq.1, 0.ltoreq.z.ltoreq.1, x+y+z.ltoreq.1, and the positive electrode active material may be further selected from at least one of sulfide, selenide, halide. More preferably, the positive electrode active material may be selected from at least one of LiCoO2、LiFePO4、LiFe0.4Mn0.6PO4、LiMn2O4、LiNi0.5Co0.2Mn0.3O2、LiNi0.6Co0.2Mn0.2O2、LiNi0.7Co0.1Mn0.2O2、LiNi0.8Co0.1Mn0.1O2、LiNi0.8Co0.15Al0.05O2、LiNi0.5Co0.2Mn0.2Al0.1O2、LiNi0.9Co0.05Mn0.05O2.
In some embodiments, the positive electrode further comprises a positive electrode current collector, and the positive electrode material layer is disposed on a surface of the positive electrode current collector.
The positive current collector is selected from a metal material that can conduct electrons, preferably, the positive current collector includes at least one of Al, ni, tin, copper, stainless steel, and in a more preferred embodiment, the positive current collector is selected from aluminum foil.
In some embodiments, the positive electrode active material layer further comprises a positive electrode binder and a positive electrode conductive agent, and the positive electrode active material, the positive electrode binder and the positive electrode conductive agent are blended to obtain the positive electrode material layer.
The positive electrode binder includes thermoplastic resins such as polyvinylidene fluoride, a copolymer of vinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene, a copolymer of tetrafluoroethylene-perfluoroalkyl vinyl ether, a copolymer of ethylene-tetrafluoroethylene, a copolymer of vinylidene fluoride-trifluoroethylene, a copolymer of vinylidene fluoride-trichloroethylene, a copolymer of vinylidene fluoride-fluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, polyethylene, polypropylene, and the like; an acrylic resin; and at least one of styrene butadiene rubber.
The positive electrode conductive agent comprises at least one of conductive carbon black, conductive carbon spheres, conductive graphite, conductive carbon fibers, carbon nanotubes, graphene or reduced graphene oxide.
In some embodiments, the anode includes an anode material layer including an anode active material, and the kind and content of the anode active material are not particularly limited and may be selected according to actual requirements.
In a preferred embodiment, the secondary battery is a lithium ion battery, and the negative electrode active material of the secondary battery comprises at least one of a carbon-based negative electrode, a silicon-based negative electrode, a tin-based negative electrode and a lithium negative electrode. Wherein the carbon-based negative electrode may include graphite, hard carbon, soft carbon, graphene, mesophase carbon microspheres, and the like; the silicon-based anode may include a silicon material, an oxide of silicon, a silicon-carbon composite material, a silicon alloy material, or the like; the tin-based negative electrode may include tin, tin carbon, tin oxygen, and tin metal compounds; the lithium negative electrode may include metallic lithium or a lithium alloy. The lithium alloy may specifically be at least one of a lithium silicon alloy, a lithium sodium alloy, a lithium potassium alloy, a lithium aluminum alloy, a lithium tin alloy, and a lithium indium alloy.
In some embodiments, the negative electrode further comprises a negative electrode current collector, and the negative electrode material layer is disposed on a surface of the negative electrode current collector. The material of the negative electrode current collector may be the same as that of the positive electrode current collector, and will not be described again.
In some embodiments, the negative electrode material layer further comprises a negative electrode binder and a negative electrode conductive agent, and the negative electrode active material, the negative electrode binder and the negative electrode conductive agent are blended to obtain the negative electrode material layer. The negative electrode binder and the negative electrode conductive agent may be the same as the positive electrode binder and the positive electrode conductive agent, respectively, and will not be described again here.
In some embodiments, a separator is further included in the secondary battery, the separator being positioned between the positive electrode and the negative electrode.
The membrane can be an existing conventional membrane, and can be a ceramic membrane, a polymer membrane, a non-woven fabric, an inorganic-organic composite membrane and the like, including but not limited to a membrane such as single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP/PE, double-layer PP/PP, and three-layer PP/PE/PP.
The invention is further illustrated by the following examples.
Additive B employed in the following examples is shown in table 1 below:
TABLE 1
Example 1
The embodiment is used for explaining the preparation method of the nonaqueous electrolyte and the lithium ion battery, and comprises the following operation steps:
1) Preparation of nonaqueous electrolyte:
ethylene Carbonate (EC), diethyl carbonate (DEC) and ethylmethyl carbonate (EMC) were mixed in a volume ratio EC: DEC: emc=1:1:1, and then lithium hexafluorophosphate (LiPF 6) was added to a molar concentration of 1.1mol/L, and additives were added in amounts of the respective additive types and contents shown in table 2, based on 100% of the total weight of the nonaqueous electrolytic solution.
2) Preparation of a positive plate:
The positive electrode active material lithium nickel cobalt manganese oxide LiNi 0.6Co0.2Mn0.2O2, conductive carbon black Super-P and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 93:4:3, and then dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. And uniformly coating the slurry on two sides of an aluminum foil, drying, calendaring and vacuum drying, and welding an aluminum outgoing line by using an ultrasonic welding machine to obtain the positive plate.
3) Preparing a negative plate:
The negative electrode active material artificial graphite, conductive carbon black Super-P, binder styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) were mixed in a mass ratio of 95:1:2:2, and then dispersed in deionized water to obtain a negative electrode slurry. And uniformly coating the slurry on two sides of the copper foil, drying, calendaring and vacuum drying, and welding an aluminum outgoing line by using an ultrasonic welding machine to obtain the negative plate.
4) Preparation of the battery cell:
And placing a diaphragm between the positive plate and the negative plate, winding a sandwich structure formed by the positive plate, the negative plate and the diaphragm, flattening the winding body, putting the flattened winding body into an aluminum foil packaging bag, and baking the aluminum foil packaging bag for 48 hours at the temperature of 75 ℃ in vacuum to obtain the battery cell to be injected with the liquid.
5) And (3) filling and forming the battery cell:
In a glove box with the dew point controlled below-40 ℃, the prepared electrolyte is injected into a battery cell, and the battery cell is subjected to vacuum packaging and is kept for 24 hours.
Then the first charge is conventionally formed by the following steps: and (3) carrying out constant current charging at 0.05C for 180min, carrying out constant current charging at 0.2C to 3.95V, carrying out secondary vacuum sealing, then further carrying out constant current charging at 0.2C to 4.35V, and carrying out constant current discharging at 0.2C to 3.0V after standing at normal temperature for 24hr to obtain the LiNi 0.6Co0.2Mn0.2O2/artificial graphite lithium ion battery.
Examples 2 to 16
Examples 2 to 16 are for explaining the nonaqueous electrolytic solution and the battery thereof disclosed in the present invention, and include most of the operation steps in example 1, which are different in that:
The types and contents of additives in the preparation of the nonaqueous electrolytic solutions were different, as shown in table 2.
Comparative examples 1 to 24
Comparative examples 1 to 24 are for comparative explanation of the nonaqueous electrolytic solution and the battery thereof disclosed in the present invention, and include most of the operation steps in example 1, which are different in that:
The types and contents of additives in the preparation of the nonaqueous electrolytic solutions were different, as shown in table 2.
Performance testing
The following performance tests were performed on the lithium ion batteries prepared in examples 1 to 16 and comparative examples 1 to 24: high temperature storage Performance test
And (3) charging the lithium ion battery after formation to 4.35V at normal temperature under a constant current of 1C, charging under a constant current and constant voltage until the current is reduced to 0.05C, discharging under a constant current of 1C to 3.0V, measuring the initial discharge capacity D1 and the initial battery volume V1 of the battery, charging until the full charge is stored for 30 days in a 60 ℃ environment, discharging under 1C to 3V, and measuring the holding capacity D2, the recovery capacity D3 and the battery volume V2 after storage of the battery.
The calculation formula is as follows:
battery capacity retention (%) =retention capacity D2/initial capacity d1×100%;
Battery capacity recovery rate (%) =recovery capacity D3/initial capacity d1×100%;
volume expansion ratio (%) = (battery volume after storage V2-initial battery volume V1)/initial battery volume v1×100%;
High temperature cycle performance test
And (3) charging the lithium ion battery after formation to 4.35V at 45 ℃ with a constant current of 1C, charging with a constant current and a constant voltage until the current is reduced to 0.05C, discharging with a constant current of 1C to 3.0V, measuring the discharge capacity of the battery at the 1 st week and the initial impedance at the 1 st week, and circularly charging and discharging for 1000 weeks according to the method. The calculation formula is as follows:
capacity retention (%) = 1000 th week discharge capacity/1 st week discharge capacity x 100%;
Internal resistance increase rate (%) = (1000 th week impedance-1 st week initial impedance)/1 st week initial impedance×100%.
The test results obtained are filled in table 2.
TABLE 2
As can be seen from the test results of examples 1 to 10 and comparative examples 1 to 6 and 13 to 18, compared with the nonaqueous electrolyte which is singly used with the additive a or singly used with the additive B, the nonaqueous electrolyte which is simultaneously added with the additive a and the additive B is applied to a lithium ion battery, the high-temperature cycle performance and the high-temperature storage performance of the lithium ion battery can be more effectively improved, and a better synergistic effect between the additive a and the additive B is demonstrated, wherein the unsaturated hydrocarbon group of the additive a can be polymerized on the surface of a negative electrode to form a phosphorus-containing SEI film in a formation stage, and after the additive a is reduced, free radicals generated by P-O fracture are diffused to the surface of a positive electrode to be oxidized, and a CEI film can be formed on the surface of the positive electrode.
From the test results of examples 1 to 6, it is understood that, in the nonaqueous electrolyte provided by the invention, when the addition amount of the additive A is fixed, the high-temperature cycle capacity retention rate and the high-temperature storage capacity retention rate of the obtained lithium ion battery all show a tendency of increasing and then decreasing with the increase of the addition amount of the additive B; from the test results of examples 7 to 10, it was revealed that, when the addition amount of the additive B was fixed, the high-temperature cycle capacity retention rate and the high-temperature storage capacity retention rate of the obtained lithium ion battery also exhibited a tendency of first increasing and then decreasing as the addition amount of the additive a was increased, indicating that the addition of both the excessive additive a and the excessive additive B was not favorable for the improvement of the high-temperature stability of the interfacial film, and that when the additive a and the additive B were in a proper compounding ratio, excellent high-temperature performance of the battery could be ensured.
As can be seen from the test results of examples 11 to 16 and comparative examples 7 to 12 and 19 to 24, the electrolyte system provided by the invention adopts different types of additives A and different types of additives B for combination, and the obtained lithium ion battery has better high-temperature electrochemical performance, so that the electrolyte system provided by the invention is applicable to different additives A and additives B and has universality.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.

Claims (10)

1. A non-aqueous electrolyte comprising a solvent, an electrolyte salt, and an additive comprising additive a and additive B, wherein:
the additive A is selected from compounds shown in a structural formula I:
Wherein R 6、R7、R8 is independently selected from C1-C5 alkyl or haloalkyl, C2-C5 unsaturated hydrocarbon or unsaturated halogenated hydrocarbon, and at least one of R 6、R7、R8 is unsaturated hydrocarbon or unsaturated halogenated hydrocarbon;
the additive B is obtained by bonding a compound shown in a structural formula II with at least one of a group A or a group B:
Wherein n is 0 or 1; r 1、R2、R3、R4、R5 is independently selected from an alkoxy group of H, C 1～C5, a hydroxyl group or an alkyl group containing a hydroxyl group and having a carbon number of C 1～C5, and R 1～R5 contains at least 4 hydroxyl groups;
wherein in the structural formula II, an oxygen atom of a hydroxyl group is bonded with one or two of the group A and the group B, and the bonding position is represented;
2. The nonaqueous electrolyte according to claim 1, wherein the additive B is selected from at least one of the following compounds:
3. The nonaqueous electrolyte according to claim 1, wherein the C1-C5 alkyl group is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl and neopentyl; a C1-C5 haloalkyl group selected from the group consisting of a halogen substituted for one or more hydrogen elements in said C1-C5 alkyl group; the unsaturated hydrocarbon group of C2-C5 is selected from ethenyl, propenyl, allyl, butenyl, pentenyl, methylvinyl, methallyl, ethynyl, propynyl, propargyl, butynyl or pentynyl, and the unsaturated halogenated hydrocarbon group of C2-C5 is selected from the group obtained by substituting one or more hydrogen elements in the unsaturated hydrocarbon group of C2-C5 with halogen.
4. The nonaqueous electrolyte according to claim 1, wherein the additive a is selected from at least one of the following compounds:
At least one of tripropylethyl phosphate, dipropylethyl methyl phosphate, dipropylethyl ethyl phosphate, dipropylethyl propyl phosphate, dipropylethyl trifluoromethyl phosphate, dipropylethyl-2, 2-trifluoroethyl phosphate, dipropylethyl-3, 3-trifluoropropyl phosphate, dipropylethyl hexafluoroisopropyl phosphate, triallyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl-2, 2-trifluoroethyl phosphate, diallyl-3, 3-trifluoropropyl phosphate, diallyl hexafluoroisopropyl phosphate.
5. The nonaqueous electrolytic solution according to claim 1, wherein the content of the additive a is 0.01 to 5% by mass and the content of the additive B is 0.01 to 10% by mass based on 100% by mass of the total nonaqueous electrolytic solution.
6. The nonaqueous electrolytic solution according to claim 1, wherein the electrolyte salt is selected from lithium salts selected from at least one of LiPF6、LiBOB、LiDFOB、LiPO2F2、LiBF4、LiSbF6、LiAsF6、LiN(SO2CF3)2、LiN(SO2C2F5)2、LiC(SO2CF3)3、LiN(SO2F)2、LiClO4、LiAlCl4、LiSO3F、LiCF3SO3、Li2B10Cl10、 lower aliphatic carboxylic acid lithium salts.
7. The nonaqueous electrolytic solution according to claim 1, wherein the concentration of the lithium salt is 0.1mol/L to 8mol/L.
8. The nonaqueous electrolytic solution according to claim 1, wherein the solvent comprises at least one of an ether-based solvent, a nitrile-based solvent, a carbonate-based solvent, a carboxylate-based solvent, and a sulfone-based solvent.
9. A secondary battery comprising a positive electrode, a negative electrode and the nonaqueous electrolyte according to any one of claims 1 to 8.
10. The secondary battery according to claim 9, wherein the secondary battery is a lithium metal battery, a lithium ion battery, or a lithium sulfur battery.
CN202310749531.XA 2022-12-29 2023-06-25 Nonaqueous electrolyte and secondary battery Pending CN118281326A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202211728220 2022-12-29
CN2022117282207 2022-12-29

Publications (1)

Publication Number Publication Date
CN118281326A true CN118281326A (en) 2024-07-02

Family

ID=91635228

Family Applications (8)

Application Number Title Priority Date Filing Date
CN202310751481.9A Pending CN118281327A (en) 2022-12-29 2023-06-25 Nonaqueous electrolyte and secondary battery
CN202310749531.XA Pending CN118281326A (en) 2022-12-29 2023-06-25 Nonaqueous electrolyte and secondary battery
CN202310775980.1A Pending CN118281329A (en) 2022-12-29 2023-06-28 Nonaqueous electrolyte and secondary battery
CN202310775983.5A Pending CN118281330A (en) 2022-12-29 2023-06-28 Nonaqueous electrolyte and secondary battery
CN202310775884.7A Pending CN118281316A (en) 2022-12-29 2023-06-28 Non-aqueous electrolyte of sodium ion battery and sodium ion battery
CN202310775885.1A Pending CN118281328A (en) 2022-12-29 2023-06-28 Nonaqueous electrolyte and secondary battery
CN202310775987.3A Pending CN118281331A (en) 2022-12-29 2023-06-28 Nonaqueous electrolyte and secondary battery
CN202310776037.2A Pending CN118281332A (en) 2022-12-29 2023-06-28 Nonaqueous electrolyte and secondary battery

Family Applications Before (1)

Application Number Title Priority Date Filing Date
CN202310751481.9A Pending CN118281327A (en) 2022-12-29 2023-06-25 Nonaqueous electrolyte and secondary battery

Family Applications After (6)

Application Number Title Priority Date Filing Date
CN202310775980.1A Pending CN118281329A (en) 2022-12-29 2023-06-28 Nonaqueous electrolyte and secondary battery
CN202310775983.5A Pending CN118281330A (en) 2022-12-29 2023-06-28 Nonaqueous electrolyte and secondary battery
CN202310775884.7A Pending CN118281316A (en) 2022-12-29 2023-06-28 Non-aqueous electrolyte of sodium ion battery and sodium ion battery
CN202310775885.1A Pending CN118281328A (en) 2022-12-29 2023-06-28 Nonaqueous electrolyte and secondary battery
CN202310775987.3A Pending CN118281331A (en) 2022-12-29 2023-06-28 Nonaqueous electrolyte and secondary battery
CN202310776037.2A Pending CN118281332A (en) 2022-12-29 2023-06-28 Nonaqueous electrolyte and secondary battery

Country Status (1)

Country Link
CN (8) CN118281327A (en)

Also Published As

Publication number Publication date
CN118281331A (en) 2024-07-02
CN118281330A (en) 2024-07-02
CN118281329A (en) 2024-07-02
CN118281332A (en) 2024-07-02
CN118281316A (en) 2024-07-02
CN118281327A (en) 2024-07-02
CN118281328A (en) 2024-07-02

Similar Documents

Publication Publication Date Title
JP7055884B2 (en) Non-aqueous electrolyte solution and lithium secondary battery containing it
CN114497692B (en) Secondary battery
WO2023045948A1 (en) Secondary battery
CN114583270B (en) Lithium ion battery
US20240136577A1 (en) Secondary Battery
CN114552004A (en) Non-aqueous electrolyte and secondary battery
CN114361588B (en) Lithium ion battery
CN115117452A (en) Lithium ion battery
CN114725512A (en) Non-aqueous electrolyte and secondary battery
CN115020813A (en) Lithium ion battery
WO2022218144A1 (en) Lithium-ion battery
JP2024500789A (en) lithium ion battery
WO2024120053A1 (en) Lithium-ion battery
WO2023016412A1 (en) Non-aqueous electrolyte solution and battery
WO2023104038A1 (en) Secondary battery
WO2023016411A1 (en) Non-aqueous electrolyte solution and battery
WO2023279953A1 (en) Non-aqueous electrolyte and battery
CN118281326A (en) Nonaqueous electrolyte and secondary battery
CN117175015B (en) Nonaqueous electrolyte and battery
WO2024016897A1 (en) Non-aqueous electrolyte solution and secondary battery
CN117673462A (en) Nonaqueous electrolyte and secondary battery
CN116826170A (en) Nonaqueous electrolyte and lithium ion battery
CN117728026A (en) Lithium ion battery
CN117895075A (en) Nonaqueous electrolyte and secondary battery
CN117219854A (en) Lithium ion battery

Legal Events

Date Code Title Description
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination