CN117039156A - Secondary battery electrolyte and secondary battery - Google Patents

Secondary battery electrolyte and secondary battery Download PDF

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Publication number
CN117039156A
CN117039156A CN202311073254.1A CN202311073254A CN117039156A CN 117039156 A CN117039156 A CN 117039156A CN 202311073254 A CN202311073254 A CN 202311073254A CN 117039156 A CN117039156 A CN 117039156A
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lithium
secondary battery
battery electrolyte
additive
carbonate
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Inventor
王霹霹
毛冲
王晓强
黄秋洁
欧霜辉
井光辉
戴晓兵
冯攀
韩晖
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Huainan Saiwei Electronic Materials Co ltd
Hefei Saiwei Electronic Materials Co ltd
Zhuhai Smoothway Electronic Materials Co Ltd
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Huainan Saiwei Electronic Materials Co ltd
Hefei Saiwei Electronic Materials Co ltd
Zhuhai Smoothway Electronic Materials Co Ltd
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Priority to CN202311073254.1A priority Critical patent/CN117039156A/en
Publication of CN117039156A publication Critical patent/CN117039156A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Secondary Cells (AREA)

Abstract

The application discloses a secondary battery electrolyte and a secondary battery, wherein the secondary battery electrolyte comprises lithium salt, an organic solvent and an additive, and the additive is a compound shown in a structural formula 1 or a structural formula 2:wherein R is 1 ～R 4 Each independently selected from hydrogen, halogen, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 unsaturated bond, silane compound. The secondary battery electrolyte adopts the compound as an additive, can form a stable interfacial film at the interface, and is favorable for improving the circulation and high-temperature performance; meanwhile, the additive contains an N-Si structure, so that the circulation stability of the electrolyte is further improved; and Si atoms in the N-Si structure can effectively absorb fluorineIons form pentavalent silane intermediate, and are further converted into fluorinated silane-based compound, and the fluorinated silane-based compound participates in the formation of SEI film at the negative electrode, reduces the impedance of an interfacial film, reduces internal resistance and improves the rate capability of the secondary battery.

Description

Secondary battery electrolyte and secondary battery
Technical Field
The application belongs to the technical field of lithium ion batteries, and particularly relates to secondary battery electrolyte and a secondary battery.
Background
Ternary medium-high nickel material LiNi x Co y Mn z O 2 (x+y+z＝1，x>0.6 Has the advantages of high working voltage, large capacity, low cost, no toxicity and the like, and is a preferable material for the anode of a Lithium Ion Battery (LIBs). However, the ternary medium-high nickel material can have structural change under higher working voltage, and meanwhile, the electrolyte and the high-activity Ni 4+ Side reactions occur between the two, which cause oxidative decomposition of the electrolyte, thus preventing commercial application thereof. In order to improve the structural stability and electrochemical performance of the ternary middle-high nickel cathode material, the stability of the electrolyte should also be considered.
Commercial lithium ion battery electrolytes are typically made from 1M LiPF 6 Is dissolved in a mixed solvent of cyclic and linear carbonates. LiPF (LiPF) 6 Is widely used due to its high ionic conductivity, good oxidation resistance and good compatibility with aluminum current collectors. However, liPF 6 Has low thermal stability, and can react with trace water to form PF 5 And acidic compounds such as HF. These acidic compounds may reduce the stability of the SEI and HF may cause dissolution of metal ions in the cathode material, which is a great detriment to battery performance. Therefore, under the condition of high voltage, the ternary middle-high nickel anode material pair promotes LiPF in the electrolyte 6 Is very important in the stability of the battery. On the other hand, the common organic solvent of the electrolyte is a carbonate solvent, also called as carbonate electrolyte, and is extremely easy to be catalyzed and oxidized by ternary middle-high nickel cathode materials under high voltage, so that the electrolyte is decomposed, and the cycle performance and the high-temperature performance are attenuated.
Therefore, there is a need to develop a method for stabilizing LiPF 6 But also can resist high-voltage electrolyte, thereby realizing excellent exertion of the electric performance of the lithium ion battery and solving the defects of the prior art.
Disclosure of Invention
Aiming at the defects of the prior art, the application solves the technical problems by seeking to adopt a special additive in the electrolyte, wherein the additive acts in the electrolyte, can reduce the surface activity of the positive electrode material under the high-voltage condition to inhibit the oxidative decomposition of the electrolyte, and can also stabilize the electrolyte.
In order to achieve the above object, the present application provides a secondary battery electrolyte comprising a lithium salt, an organic solvent, and an additive, the additive being a compound represented by structural formula 1 or structural formula 2:
wherein R is 1 ～R 4 Each independently selected from hydrogen, halogen, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 unsaturated bond, silane compound.
Compared with the prior art, the secondary battery electrolyte adopts the compound shown in the structural formula 1 or the structural formula 2 as the additive, and the nitrogen-containing heterocycle ring-opening polymerization in the structural additive can be utilizedThe interface membrane is combined at the interface to form a stable interface membrane, and the interface membrane has a good conductive lithium ion channel, thereby being beneficial to improving the circulation and high-temperature performance; meanwhile, the additive contains an N-Si structure, the silane group functional group can effectively capture F ions from HF, and the N atom can be combined with LiPF 6 Decomposition to yield the strong Lewis acid PF 5 Formation of coordination complexes to improve LiPF 6 Dissociation degree of (c) and reduction of ion pair LiPF 6 The formation of the electrolyte improves the circulation stability of the electrolyte; meanwhile, si atoms in the N-Si structure of the structure can effectively absorb fluorine ions to form a pentavalent silane intermediate, the intermediate can be further converted into a fluorinated silane-based compound, the substance can further participate in the formation of an SEI film at a negative electrode, the impedance of an interface film is reduced, the internal resistance is reduced, and the rate capability of a secondary battery (lithium ion battery) is improved.
Wherein, C1-C6 alkyl represents alkyl or silane group with 1-6 carbon atoms, alkyl can be chain alkyl, can also be cycloalkyl, hydrogen located on the ring of cycloalkyl can be substituted by alkyl, and as an example, alkyl can be but not limited to methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, cyclohexyl and the like.
Wherein the unsaturated bond of C1-C6 represents a hydrocarbon group having 1-6 carbon atoms, and may be a cyclic alkenyl group or an alkenyl group. Further, the hydrocarbyl group may be, but is not limited to, alkenyl, alkynyl, nitrile, and the like. By way of example, alkenyl groups include, but are not limited to, ethenyl, propenyl, 1-propenyl, isopropenyl, 2-butenyl, 1, 3-butadienyl, and the like. Illustratively, alkynyl groups include, but are not limited to, ethynyl, 2-propynyl, 1 dimethyl-2-propynyl, and the like.
The silane compound may be a cyclic silane group or a chain silane group. Further, the silane groups may be, but are not limited to, trimethylsilyl, diethylvinylsilyl, tripropylsilyl, and (3-cyanopropyl) dimethylsilyl, and the like.
In some embodiments, the additive is selected from at least one of compounds 1 to 6:
preferably, the additive is selected from compound 4, which has a better effect on the stability of the electrolyte due to the more N-Si structure of compound 4.
In some embodiments, the mass of the additive is 0.2-4% of the total mass of the electrolyte, and further, the mass of the additive is 0.5-3% of the total mass of the electrolyte. By way of example, the mass of the additive may be 0.1%, 0.3%, 0.5%, 0.8%, 1.2%, 1.5%, 2%, 2.5%, 3% of the total mass of the electrolyte, but is not limited to the recited values, and other non-recited values within this range are equally applicable.
In some embodiments, the lithium salt is selected from lithium hexafluorophosphate (LiPF 6 ) Lithium perchlorate (LiClO) 4 ) Lithium tetrafluoroborate (LiBF) 4 ) Lithium methylsulfonate (LiCH) 3 SO 3 ) Lithium triflate (LiCF) 3 SO 3 ) Lithium bis (trifluoromethylsulfonyl) imide (LiN (CF) 3 SO 2 ) 2 ) Lithium dioxaborate (LiBOB), lithium difluorooxalato borate (LiDFOB), lithium difluorophosphate (LiPO) 2 F 2 ) Lithium difluorobis (oxalato) phosphate (LiDFBP), lithium difluorosulfonimide (LiLSI), lithium bistrifluoromethylsulfonimide (LiTFSI), lithium fluorosulfonate (LiSO) 2 F) Lithium diphosphate (LiPO) 2 F 2 ) And at least one of lithium lower aliphatic carboxylate. As an example, the lithium salt is lithium hexafluorophosphate or lithium tetrafluoroborate.
In some embodiments, the mass of the lithium salt is 5-30% of the total mass of the electrolyte, further, the mass of the lithium salt is 6-20% of the total mass of the electrolyte, and preferably, the mass of the lithium salt is 8-18% of the total mass of the electrolyte. By way of example, the mass of lithium salt is 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18% of the total mass of the electrolyte, but is not limited to the recited values, and other non-recited values within this range are equally applicable.
In some embodiments, the organic solvent is selected from at least one of carbonates, carboxylates, ethers, and heterocyclic compounds. For example, the nonaqueous organic solvent is selected from at least one of cyclic carbonates, chain carbonates, cyclic esters, chain esters, cyclic ethers, chain ethers, sulfone compounds, sulfoxide compounds, and ionic liquids. Further, the carbonates may be, but are not limited to, chain carbonates, cyclic carbonates. As examples, cyclic carbonates such as: ethylene Carbonate (EC), propylene Carbonate (PC), butylene Carbonate (BC), pentylene carbonate, vinylene Carbonate (VC) or derivatives thereof. In some embodiments, the organic solvent is at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl Methyl Carbonate (EMC), and Propylene Carbonate (PC). In some embodiments, the organic solvent is a carboxylate solvent, which includes a cyclic carboxylate and/or a chain carbonate, which may include, but is not limited to: at least one of gamma-butyrolactone, gamma-valerolactone and delta-valerolactone; as the chain carbonate, specific ones may include, but are not limited to: 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 organic solvent is an ether solvent, including cyclic or chain ethers, which may include, but are not limited to, 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); the chain ether may specifically include, but is not limited to, at least one of dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether.
In some embodiments, the electrolyte of the present application further comprises an auxiliary agent selected from at least one of ethylene carbonate, fluoroethylene carbonate, ethylene sulfite, 1,3 propane sultone, 1, 3-propane sultone, 1, 4-butane sultone, ethylene sulfate, succinic anhydride, maleic anhydride, 2-methyl maleic anhydride, 2-propynyl methyl carbonate, tetravinyl silane, triallyl isocyanurate, hexamethylene diiso-nitrile, phenanthroline, p-phenylene diisocyanate, 2, 4-toluene diisocyanate, N-phenyl bis (trifluoromethanesulfonyl) imide, vinyl disulfate, phenyl methane sulfonate, vinyl disulfate, propylene bisspiro sulfate, hydroquinone difluorosulfonate, triallyl phosphate, tripropyl phosphate, 2, 4-butane sultone, isocyanatoethyl methacrylate, methylene methane disulfonate, tris (trimethylsilyl) borate, tris (trimethylsilyl) phosphate, tris (vinyldisilane) phosphate. Illustratively, the auxiliary agent is fluoroethylene carbonate (FEC), and the addition of the auxiliary agent is beneficial to film formation so as to improve the electrochemical performance of the lithium ion battery.
In some embodiments, the mass of the auxiliary agent accounts for 1-10.0% of the total mass of the electrolyte, further, the mass of the auxiliary agent accounts for 1.5-8% of the total mass of the electrolyte, and preferably, the mass of the auxiliary agent accounts for 2-6% of the total mass of the electrolyte. Illustratively, the auxiliary agent comprises 2%, 2.5%, 3%, 4%, 4.5%, 5%, 5.5%, 6.0% of the total electrolyte mass, but is not limited to the recited values, and other non-recited values within the range are equally applicable.
Correspondingly, the application also provides a secondary battery which comprises a positive electrode, a negative electrode and the secondary battery electrolyte. The secondary battery comprises, but is not limited to, a lithium ion battery, when the secondary battery electrolyte is used in the secondary battery, good high-low temperature discharge performance can be still realized when the highest charging voltage is 4.4V, the rate capability is improved, and the cycle life of the battery is obviously prolonged.
In some embodiments, the positive electrode active material may include at least one of the following materials: olivine structured lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (e.g., liCoO) 2 ) Lithium nickel oxide (e.g. LiNiO 2 ) Lithium manganese oxide (e.g. LiMnO 2 、LiMn 2 O 4 ) Lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (structure such as LiNi x Co y Mn (1-x-y) M z O 2 Wherein 0.6.ltoreq.x<0.9，x+y<1，0≤z<0.08, M is at least one of Al, mg, zr and Ti). Examples of olivine structured lithium-containing phosphates may include, but are not limited to, lithium iron phosphate (e.g., liFePO 4 (also referred to as LFP for short)), a composite of lithium iron phosphate and carbon, a composite of lithium manganese phosphate (e.g., liMnPO 4), a composite of lithium manganese phosphate and carbon, a composite of lithium manganese phosphate, lithium manganese phosphate and carbon.
In some embodiments, the negative electrode active material includes 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.
Detailed Description
For a better description of the objects, technical solutions and advantageous effects of the present application, the present application will be further described with reference to specific examples. It should be noted that the following implementation of the method is a further explanation of the present application and should not be taken as limiting the present application.
Example 1
(1) Preparation of electrolyte:
mixing Ethylene Carbonate (EC), diethyl carbonate (DEC) and ethylmethyl carbonate (EMC) according to the mass ratio of EC: DEC: EMC=2:1:1 to obtain 80.5g of organic solvent, mixing, and adding 14g of lithium hexafluorophosphate (LiPF 6 ) After complete dissolution of the lithium salt, 5g of fluoroethylene carbonate (FEC) and 0.5g of additive compound are added1。
(2) Preparation of a positive plate:
ternary material LiNi of nickel cobalt lithium manganate 0.6 Co 0.2 Mn 0.2 Zr 0.03 O 2 Uniformly mixing a conductive agent SuperP, an adhesive PVDF and a Carbon Nano Tube (CNT) according to a mass ratio of 97.5:1.5:1:1 to prepare lithium ion battery anode slurry with certain viscosity, coating the mixed slurry on two sides of an aluminum foil, and drying and rolling to obtain the anode plate.
(3) Preparing a negative plate:
mixing artificial graphite and silicon according to the mass ratio of 90:10, preparing slurry with a conductive agent SuperP, a thickening agent CMC and an adhesive SBR (styrene butadiene rubber emulsion) according to the mass ratio of 95:2:1:2, uniformly mixing, coating the mixed slurry on two sides of a copper foil, drying, and rolling to obtain a negative plate, thus preparing the negative plate of the lithium ion battery meeting the requirements.
(4) Preparation of a lithium ion battery:
and (3) manufacturing the positive electrode, the diaphragm and the negative electrode into square battery cells in a lamination mode, packaging by adopting polymers, filling the prepared lithium ion battery nonaqueous electrolyte, and manufacturing the lithium ion battery with the capacity of 1000mAh through the working procedures of formation, capacity division and the like.
The electrolyte compositions of examples 2 to 9 and comparative example 1 are shown in table 1, and the procedure for preparing the electrolyte and the lithium ion battery is the same as in example 1.
Table 1 electrolyte compositions of examples and comparative examples
The lithium ion batteries prepared in examples 1 to 9 and comparative example 1 were subjected to a normal temperature cycle test, a high temperature storage test, a low temperature discharge test, and an electrolyte storage acid value stability, respectively, according to the following test conditions, and the test results are shown in tables 2 and 3.
Normal temperature cycle test：
The lithium ion battery is charged and discharged at the normal temperature (25 ℃) at 1.0C/1.0C (the discharge capacity of the battery is C) 0 ) The upper limit voltage was 4.4V, and then charging and discharging at 1.0C/1.0C was performed for 500 weeks under normal temperature conditions (the discharge capacity of the battery was C) 1 )；
Capacity retention= (C 1 /C 0 )*100％
High temperature cycle test：
The lithium ion battery is charged and discharged at 1.0C/1.0C once under the condition of high temperature (45 ℃) (the discharge capacity of the battery is C) 0 ) The upper limit voltage was 4.4V, and then charging and discharging at 1.0C/1.0C was performed for 300 weeks under normal temperature conditions (the battery discharge capacity was C) 1 )；
Capacity retention= (C 1 /C 0 )*100％
High temperature storage test：
Lithium ion batteries were charged and discharged at 0.3C/0.3C once (the discharge capacity of the battery was recorded as C) at normal temperature (25 ℃ C.) 0 ) The upper limit voltage is 4.4V; placing the battery in a 60 ℃ oven for 15d, taking out the battery, placing the battery in a 25 ℃ environment, discharging at 0.3C, and recording the discharge capacity as C 1 The method comprises the steps of carrying out a first treatment on the surface of the The lithium ion battery was then charged and discharged once at 0.3C/0.3C (the discharge capacity of the battery was recorded as C) 2 )；
Capacity retention= (C 1 /C 0 )*100％
Capacity recovery rate= (C 2 /C 0 )*100％
Low temperature discharge test：
Lithium ion batteries were charged and discharged at 0.3C/0.3C once (the discharge capacity of the battery was recorded as C) at normal temperature (25 ℃ C.) 0 ) The upper limit voltage is 4.4V; placing the battery in an oven at-20 ℃ for 4 hours, discharging the battery at 0.3C, and recording the discharge capacity as C 1 The cut-off voltage was 3.0V,
capacity retention rate＝(C 1 /C 0 )*100％
Table 2 results of performance tests of lithium ion batteries of examples and comparative examples
TABLE 3 acid number stability test results of electrolyte
As is clear from Table 2, the electrolyte of comparative example 1 does not contain additives, and has unsatisfactory high-temperature storage performance, high-temperature cycle performance and low-temperature discharge performance, whereas the lithium ion batteries prepared from the electrolytes of examples 1 to 9 have good high-temperature storage performance, cycle performance and low-temperature discharge performance. The secondary battery electrolyte adopts the compound shown in the structural formula 1 or the structural formula 2 as an additive, and can form a stable interfacial film at an interface by means of ring-opening polymerization of a nitrogen-containing heterocycle in the structural additive, and the interfacial film has a good lithium ion conduction channel, thereby being beneficial to improving the circulation and high-temperature performance; meanwhile, the additive contains an N-Si structure, the silane group functional group can effectively capture F ions from HF, and the N atom can be combined with LiPF 6 Decomposition to yield the strong Lewis acid PF 5 Formation of coordination complexes to improve LiPF 6 Dissociation degree of (c) and reduction of ion pair LiPF 6 The formation of the electrolyte improves the circulation stability of the electrolyte; meanwhile, si atoms in the N-Si structure of the structure can effectively absorb fluorine ions to form a pentavalent silane intermediate, the intermediate can be further converted into a fluorinated silane-based compound, the substance can further participate in the formation of an SEI film at a negative electrode, the impedance of an interface film is reduced, the internal resistance is reduced, and the rate capability of a secondary battery (lithium ion battery) is improved.
As is also apparent from table 2, the hydrogen radical functional group can improve the high temperature storage performance, but the normal temperature, high temperature cycle and low temperature discharge performance are all deteriorated as is apparent from comparison of example 1 and example 3. As can be seen from comparison of example 1 with example 4, compound 4 has more N-Si structure, and thus has better storage properties at normal temperature and high temperature than compound 1. As can be seen from comparison of examples 1, 7 and 8, the compound 1 has relatively good comprehensive properties at 1%, thin film formation at 0.5% and relatively thick film formation at 2%, which are detrimental to the performance of the battery.
From Table 3, it is understood that the acid value stability of the electrolyte solution stored after the addition of the compounds 1 to 6 in examples 1 to 6 was significantly improved and maintained at a relatively low level as compared with comparative example 1. It is further understood that the acid value stability of example 4 is significantly improved, since compound 4 has more N-Si structure, which has a better effect on the stability of the electrolyte, and the improvement of the acid value stability upon storage is most remarkable.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present application and not for limiting the scope of the present application, and although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solution of the present application without departing from the spirit and scope of the technical solution of the present application.

Claims (10)

1. The secondary battery electrolyte comprises lithium salt, an organic solvent and an additive, and is characterized in that the additive is a compound shown in a structural formula 1 or a structural formula 2:
wherein R is 1 ～R 4 Each independently selected from hydrogen, halogen, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 unsaturated bond, silane compound.
2. The secondary battery electrolyte according to claim 1, wherein the alkyl group is selected from at least one of methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, and cyclohexyl.
3. The secondary battery electrolyte according to claim 1, wherein the unsaturated bond is a hydrocarbon group selected from at least one of an alkenyl group, an alkynyl group, and a nitrile group.
4. The secondary battery electrolyte according to claim 1, wherein the silane compound is at least one selected from the group consisting of trimethylsilyl, diethylvinylsilyl, tripropylsilyl, and (3-cyanopropyl) dimethylsilyl.
5. The secondary battery electrolyte according to claim 1, wherein the additive is at least one selected from the group consisting of compounds 1 to 6:
6. the secondary battery electrolyte according to claim 1, wherein the mass of the additive is 0.2 to 4% of the total mass of the electrolyte.
7. The secondary battery electrolyte according to claim 1, wherein the lithium salt is at least one selected from the group consisting of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium methylsulfonate, lithium trifluoromethylsulfonate, lithium bistrifluoromethylsulfonimide, lithium dioxaborate, lithium difluorooxalato borate, lithium difluorophosphate, lithium difluorobisoxalato phosphate, lithium bistrifluoromethylsulfonimide and lithium bistrifluoromethylsulfonimide, lithium fluorosulfonate, lithium diphosphate and lithium lower aliphatic carboxylate.
8. The secondary battery electrolyte according to claim 1, wherein the organic solvent is at least one selected from the group consisting of ethylene carbonate, dimethyl carbonate, diethyl carbonate, methylethyl carbonate, propylene carbonate, butyl acetate, γ -butyrolactone, propyl propionate, ethyl propionate, and ethyl butyrate.
9. The secondary battery electrolyte according to claim 1, further comprising an auxiliary agent selected from at least one of vinylene carbonate, fluoroethylene carbonate, ethylene sulfite, 1,3 propane sultone, 1, 3-propenesulfonic acid lactone, 1, 4-butane sultone, ethylene sulfate, succinic anhydride, maleic anhydride, 2-methyl maleic anhydride, 2-propynyl methyl carbonate, tetravinyl silane, triallyl isocyanurate, hexamethylenediisonitrile, phenanthroline, terephthal-isocyanate, 2, 4-toluene diisocyanate, N-phenyl bis (trifluoromethanesulfonyl) imide, vinyl disulfate, phenyl methanesulfonate, vinyl disulfate, propylene bisspiro sulfate, hydroquinone difluorosulfonate, triallyl phosphate, tripropyl phosphate, 2, 4-butane sultone, isocyanatoethyl methacrylate, methylene methane disulfonate, tris (trimethylsilane) borate, tris (trimethylsilane) phosphate, tris (vinyl disilane) phosphate.
10. A secondary battery comprising a positive electrode and a negative electrode, characterized by further comprising the secondary battery electrolyte as claimed in any one of claims 1 to 9.
CN202311073254.1A 2023-08-24 2023-08-24 Secondary battery electrolyte and secondary battery Pending CN117039156A (en)

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