CN116387620A - Electrolyte and battery comprising same - Google Patents

Electrolyte and battery comprising same Download PDF

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Publication number
CN116387620A
CN116387620A CN202310292219.2A CN202310292219A CN116387620A CN 116387620 A CN116387620 A CN 116387620A CN 202310292219 A CN202310292219 A CN 202310292219A CN 116387620 A CN116387620 A CN 116387620A
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electrolyte
additive
substituted
battery
unsubstituted
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王海
李素丽
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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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
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • 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

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  • 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 invention provides an electrolyte and a battery comprising the same. The electrolyte comprises a phosphazene compound containing unsaturated bonds as a first additive, the first additive can act on the surface of a positive electrode to form an interface film with low impedance and high stability, the safety performance of the battery is obviously improved, the impedance of the battery is reduced, and meanwhile, the high-temperature cycle performance of the battery can be improved, so that the battery with good safety performance, low impedance and good high-temperature cycle performance is obtained.

Description

Electrolyte and battery comprising same
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to an electrolyte and a battery comprising the electrolyte.
Background
The lithium ion battery has the characteristics of high energy density, no memory effect, high working voltage, environmental friendliness and the like, and is widely used as a power supply of a 3C digital product. Along with the rapid development of the fields of energy storage, electric automobiles, electric tools and the like, the demand of new energy markets for lithium ion batteries is continuously improved, so that the performance demand of people for lithium ion batteries is also continuously improved, and the lithium ion batteries with high safety and low impedance are the main direction of current development.
Currently, a high safety strategy is to add a safety additive while improving the stability of the solvent system in the electrolyte, but this leads to an increase in the interfacial resistance of the battery and a deterioration in the charging ability; the effective method for improving the charging capacity is to reduce the dosage of film forming additives in the electrolyte, reduce the viscosity of the solvent and improve the conductivity, but the storage and the cycle performance of the battery are affected; therefore, development of an electrolyte solution that combines low impedance and safety is an important development direction at present.
Disclosure of Invention
In order to solve the problem that the battery in the prior art cannot achieve both low impedance and safety, the invention provides an electrolyte and a lithium ion battery comprising the same. The use of the electrolyte can obtain a safe and low-impedance battery, and simultaneously, the high-temperature cycle performance of the battery is improved.
The invention aims at realizing the following technical scheme:
an electrolyte comprises electrolyte salt, an organic solvent and a functional additive, wherein the functional additive comprises a first additive, and the first additive is a phosphazene compound containing unsaturated bonds.
According to an embodiment of the present invention, the phosphazene compound containing an unsaturated bond contains at least one nitrile group (-c≡n) and a phosphorus-carbon double bond (c=p), the nitrile group being directly linked to the phosphorus-carbon double bond; preferably, the phosphazene compound containing unsaturated bond contains two nitrile groups and a phosphorus-carbon double bond, and the nitrile groups are directly connected with carbon atoms in the phosphorus-carbon double bond.
According to an embodiment of the invention, the first additive comprises at least one of the compounds of formula I:
Figure BDA0004141957300000021
wherein R1, R2 and R3 are the same or different and are independently selected from H, halogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkenyloxy; if substituted, the substituent is halogen, alkyl or cyano.
According to an embodiment of the invention, R1, R2 and R3 are identical or different and are selected, independently of one another, from H, halogen, substituted or unsubstituted C 1-12 Alkyl, substituted or unsubstituted C 1-12 Alkoxy, substituted or unsubstituted C 2-12 Alkenyl, substituted or unsubstituted C 2-12 An alkenyloxy group; in the case of substitution, the substituents are halogen, C 1-12 Alkyl or cyano.
According to an embodiment of the invention, R1, R2 and R3 are identical or different and are selected, independently of one another, from H, halogen, substituted or unsubstituted C 1-6 Alkyl, substituted or unsubstituted C 1-6 Alkoxy, substituted or unsubstituted C 2-6 Alkenyl, substituted or unsubstituted C 2-6 An alkenyloxy group; in the case of substitution, the substituents are halogen, C 1-6 Alkyl or cyano.
According to an embodiment of the invention, R1, R2 and R3 are identical or different and are selected, independently of one another, from H, halogen, substituted or unsubstituted C 1-3 Alkyl, substituted or unsubstituted C 1-3 Alkoxy, substituted or unsubstituted C 2-3 Alkenyl, substituted or unsubstituted C 2-3 An alkenyloxy group; in the case of substitution, the substituents are halogen, C 1-3 Alkyl or cyano.
According to an embodiment of the present invention, the first additive includes at least one of the following compounds A1 to A4:
Figure BDA0004141957300000031
according to an embodiment of the invention, the first additive is present in an amount of 0.1-10 wt%, preferably 0.5-3 wt%, such as 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.2wt%, 1.3wt%, 1.5wt%, 1.6wt%, 1.8wt%, 2wt%, 2.2wt%, 2.4wt%, 2.5wt%, 2.6wt%, 2.8wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5.5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%, based on the total mass of the electrolyte.
According to an embodiment of the present invention, the first additive may be obtained commercially, or may be prepared by methods known in the art.
According to an embodiment of the invention, the functional additive further comprises a second additive comprising at least one of fluoroethylene carbonate (FEC), 1, 3-Propane Sultone (PS), ethylene sulfate (DTD), propylene Sultone (PST), maleic anhydride, citraconic anhydride, succinic anhydride, succinonitrile (SN), hexadinitrile (ADN), ethyleneglycol bis (propionitrile) ether (EGBE), hexane dinitrile (HTCN).
According to an embodiment of the invention, the second additive is present in an amount of 0.1wt% to 15wt%, preferably 5wt% to 13wt%, e.g. 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.2wt%, 1.3wt%, 1.5wt%, 1.6wt%, 1.8wt%, 2wt%, 2.2wt%, 2.4wt%, 2.5wt%, 2.6wt%, 2.8wt%, 3wt%, 3.3wt%, 3.5wt%, 3.8wt%, 4wt%, 4.2wt%, 4.5wt%, 4.8wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt% based on the total mass of the electrolyte.
According to an embodiment of the invention, the electrolyte salt is selected from electrolyte lithium salts.
According to an embodiment of the invention, the electrolyte lithium salt is selected from lithium hexafluorophosphate (LiPF) 6 ) Lithium difluorophosphate (LiPF) 2 O 2 ) Difluoro lithium bis (oxalato) phosphate (LiPF) 2 (C 2 O 4 ) 2 ) Lithium tetrafluorooxalate phosphate (LiPF) 4 C 2 O 4 ) Lithium oxalate phosphate (LiPO) 2 C 2 O 4 ) Lithium bisoxalato borate (LiBOB), lithium difluorooxalato borate (LiODFB), lithium tetrafluoroborate (LiBF) 4 ) At least one of lithium bis-fluorosulfonimide (LiTFSI) and lithium bis-fluorosulfonimide (LiFSI).
According to an embodiment of the invention, the electrolyte salt is present in an amount of 10wt% to 15wt%, for example 10wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt% based on the total mass of the electrolyte.
According to an embodiment of the present invention, the organic solvent is selected from at least one of Ethylene Carbonate (EC), propylene Carbonate (PC), diethyl carbonate (DEC), ethyl Propionate (EP), propyl Propionate (PP), ethyl Acetate (EA), ethyl n-butyrate (EB) and gamma-butyrolactone (GBL).
The invention also provides a preparation method of the electrolyte, which comprises the following steps:
the electrolyte is obtained after mixing an organic solvent, an electrolyte salt, a first additive and optionally a second additive, with or without addition.
The invention also provides a battery, which comprises the electrolyte.
According to an embodiment of the invention, the battery is a lithium ion battery.
According to an embodiment of the present invention, the battery further includes a positive electrode sheet containing a positive electrode active material, a negative electrode sheet containing a negative electrode active material, and a separator.
According to an embodiment of the present invention, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on one or both side surfaces of the positive electrode current collector, the positive electrode active material layer including a positive electrode active material, a conductive agent, and a binder.
According to an embodiment of the present invention, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one or both side surfaces of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material, a conductive agent, and a binder.
According to an embodiment of the present invention, the positive electrode active material layer comprises the following components in percentage by mass: 80 to 99.8 weight percent of positive electrode active material, 0.1 to 10 weight percent of conductive agent and 0.1 to 10 weight percent of binder.
Preferably, the positive electrode active material layer comprises the following components in percentage by mass: 90 to 99.6 weight percent of positive electrode active material, 0.2 to 5 weight percent of conductive agent and 0.2 to 5 weight percent of binder.
According to an embodiment of the present invention, the negative electrode active material layer comprises the following components in percentage by mass: 80 to 99.8 weight percent of negative electrode active material, 0.1 to 10 weight percent of conductive agent and 0.1 to 10 weight percent of binder.
Preferably, the mass percentage of each component in the anode active material layer is as follows: 90 to 99.6 weight percent of negative electrode active material, 0.2 to 5 weight percent of conductive agent and 0.2 to 5 weight percent of binder.
According to an embodiment of the present invention, the conductive agent is at least one selected from conductive carbon black, acetylene black, ketjen black, conductive graphite, conductive carbon fiber, carbon nanotube, and metal powder.
According to an embodiment of the present invention, the binder is at least one selected from sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, polyethylene oxide.
According to an embodiment of the present invention, the anode active material includes nano silicon (Si), silicon oxygen (SiO) x (0<x<2) At least one of silicon carbon, artificial graphite, natural graphite, mesophase carbon microspheres, hard carbon, soft carbon, lithium metal, lithium titanate.
According to an embodiment of the present invention, the positive electrode active material is selected from lithium transition metal composite oxides selected from LiMO 2 (M＝Ni、Co、Mn)、LiMn 2 O 4 、LiMPO 4 (M＝Fe、Mn、Co)、LiNi x Mn 1-x O 2 (M＝Co、Mn)、LiNixCo y M 1-x-y O 2 Wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 1 and x+y is more than or equal to 1; wherein M is one or more of Mg, zn, ga, ba, al, fe, cr, sn, V, mn, sc, ti, nb, mo, zr, ta, W, B, F, si.
The invention has the beneficial effects that:
the invention provides an electrolyte and a battery comprising the same. The electrolyte comprises a phosphazene compound containing unsaturated bonds as a first additive, the first additive can act on the surface of a positive electrode to form an interface film with low impedance and high stability, the safety performance of the battery is obviously improved, the impedance of the battery is reduced, and meanwhile, the high-temperature cycle performance of the battery can be improved, so that the battery with good safety performance, low impedance and good high-temperature cycle performance is obtained. Specifically, compared with the traditional nitrile compound, the phosphazene compound containing unsaturated bonds has a remarkably improved low-impedance effect, theoretical calculation shows that the phosphazene compound has lower oxidation potential, oxidation reaction is easy to occur at a positive electrode to generate a low-impedance interface film rich in P, and meanwhile, the stability of the obtained low-impedance interface film is remarkably improved due to the fact that phosphorus-carbon double bonds participate in film formation. Moreover, the nitrile group in the first additive also has the effect of complexing transition metal, the dinitrile structure connected to the phosphorus-carbon double bond has a mushroom structure, the stability of the nitrile group complexing transition metal ions can be obviously improved by the dinitrile structure, compared with the stability of the conventional nitrile compound complexing transition metal ions, the stability of the complexing transition metal ions is obviously improved, the complexed transition metal ions are not easy to transfer to the negative electrode, the stability of the negative electrode can be improved, the influence on the negative electrode is avoided, and the stability of the interface between the positive electrode and the negative electrode is obviously improved in the circulation process of the battery. Under the thermal shock working condition, the carbon-phosphorus double bond is easier to break to generate a phosphorus-containing interface film, and the phosphorus-containing interface film can improve the stability of the positive electrode, so that the thermal stability of the battery is obviously improved. Compared with the prior art, the phosphazene compound containing unsaturated bonds shown in the formula I has lower impedance and better safety performance than the traditional nitrile, and simultaneously, the high-temperature cycle performance of the battery is obviously improved.
Further, since the first additive has a higher LUMO orbital, the reduction resistance of the anode is improved, and the interfacial film formed on the surface of the anode in the first charge and discharge process has low stability and poor performance. At this time, by introducing a second additive into the electrolyte, the second additive can act on the anode surface in preference to the first additive, and an interface film of high stability can be formed on the anode surface.
When the first additive and the second additive are in synergistic action, the second additive can generate stable SEI on the surface of the negative electrode in advance, and the first additive regenerates an interface film with low impedance and improved stability, so that the thermal shock performance is improved, and meanwhile, the better cycle performance and DCR performance are obtained.
In conclusion, the safe and low-impedance electrolyte and the lithium ion battery provided by the invention have the advantages of improving the high-temperature cycle performance of the battery and showing extremely high application value.
Detailed Description
The present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are illustrative only and are not to be construed as limiting the scope of the invention. All techniques implemented based on the above description of the invention are intended to be included within the scope of the invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; the reagents, materials, etc. used in the examples described below are commercially available unless otherwise specified.
In the description of the present invention, it should be noted that the terms "first," "second," and the like are used for descriptive purposes only and are not indicative or implying relative importance.
The preparation method of the lithium ion battery comprises the following steps:
[ preparation of Positive electrode sheet ]
Mixing positive active materials Lithium Cobalt Oxide (LCO), binder polyvinylidene fluoride (PVDF), conductive carbon black and single-walled carbon nanotubes according to the weight ratio of 97.2:1.5:1.2:0.1, adding N-methyl pyrrolidone (NMP), and stirring under the action of a vacuum stirrer until the mixed system forms positive slurry with uniform fluidity; uniformly coating positive electrode slurry on a current collector aluminum foil; and baking the coated aluminum foil in 5 sections of ovens with different temperature gradients, drying the aluminum foil in an oven with the temperature of 120 ℃ for 8 hours, and rolling and slitting the aluminum foil to obtain the required positive plate.
[ preparation of negative electrode sheet ]
Mixing negative electrode active material artificial graphite, thickener sodium carboxymethylcellulose (CMC-Na), binder styrene-butadiene rubber and conductive agent acetylene black according to the weight ratio of 97:1:1:1, adding deionized water, and obtaining negative electrode slurry under the action of a vacuum stirrer; uniformly coating the negative electrode slurry on a high-strength carbon-coated copper foil to obtain a pole piece; and (3) airing the obtained pole piece at room temperature, transferring the pole piece to an 80 ℃ oven for drying for 10 hours, and then rolling and slitting to obtain the negative pole piece.
[ electrolyte preparation ]
In a glove box filled with inert gas (H 2 O<10ppm，O 2 <5 ppm), ethylene carbonate, propylene carbonateThe ester and propyl propionate were mixed in a mass ratio EC: PC: pp=1:2:4, and then 13.75wt% of lithium hexafluorophosphate (LiPF) based on the total weight of the electrolyte was slowly added to the mixed solution 6 ) And (5) obtaining the basic electrolyte after the water and the free acid are detected to be qualified. The electrolytes of the respective examples and comparative examples were obtained by adding the first additive and the second additive in different amounts in table 1 to the base electrolyte.
[ manufacturing of Battery ]
And stacking the prepared positive plate, the prepared diaphragm (9-micrometer-thick PP film) and the prepared negative plate in sequence, ensuring that the diaphragm is positioned between the positive plate and the negative plate to play a role in isolation, placing the bare cell into an aluminum plastic film outer package, injecting the prepared electrolyte into a dried battery, packaging, standing, forming, shaping and capacity-dividing, and thus completing the preparation of the lithium ion soft package battery.
Examples 1 to 10 and comparative examples 1 to 3 were prepared according to the above-described preparation methods.
Table 1 composition of electrolyte solutions of the batteries of examples and comparative examples
First additive composition and addition amount Second additive composition and additive amount
Example 1 A1:0.5wt％ 8.0wt% FEC and 3.0wt% HTCN
Example 2 A1:1.0wt％ 8.0wt% FEC and 3.0wt% HTCN
Example 3 A1:2.0wt％ 8.0wt% FEC and 3.0wt% HTCN
Example 4 A1:3.0wt％ 8.0wt% FEC and 3.0wt% HTCN
Example 5 A2:1.0wt％ 8.0wt% FEC and 3.0wt% HTCN
Example 6 A3:1.0wt％ 8.0wt% FEC and 3.0wt% HTCN
Example 7 A4:1.0wt％ 8.0wt% FEC and 3.0wt% HTCN
Example 8 A4:1.0wt％ FEC:8.0wt％
Example 9 A4:1.0wt％ HTCN:3.0wt％
Example 10 A4:1.0wt％ /
Comparative example 1 / /
Comparative example 2 / 8.0wt% FEC and 3.0wt% HTCN
Comparative example 3 / 8.0wt% FEC and 4.0wt% HTCN
Test case
The lithium ion batteries and the electrolytes obtained in examples 1 to 10 and comparative examples 1 to 3 were subjected to the performance test.
(1) High temperature cycle performance test: at 45 ℃, the battery after capacity division is charged to 4.48V according to constant current and constant voltage of 3.0C, the cut-off current is 0.05C, then the battery is discharged to 3.0V according to constant current of 0.5C, the capacity retention rate at 500 weeks is calculated after 500 cycles of charge and discharge according to the circulation, and the calculation formula is as follows:
500 th cycle capacity retention (%) = (500 th cycle discharge capacity/first cycle discharge capacity) ×100%.
(2) Thermal shock performance: discharging to 3.0V at a given current of 0.2C under ambient conditions of 25 ℃; standing for 5min; charging to 4.48V at a charging current of 0.2C, and changing to 4.48V constant voltage charging when the voltage of the battery cell reaches 4.48V until the charging current is less than or equal to a given cutoff current of 0.05C; placing the battery cell into an oven after the battery cell is placed for 1h, and raising the temperature of the oven to 132+/-2 ℃ at the speed of 5+/-2 ℃/min, and stopping after the battery cell is kept for 30min, wherein the judgment standard is that the battery cell does not fire or explode.
(3) DCR (direct current impedance) test: at normal temperature (23 ℃ +/-3 ℃), constant current and voltage are carried out at 0.5 ℃ to 4.48V, the cut-off current is 0.02 ℃, then the discharge is carried out at 0.1C for 9 hours (adjusted to 10% SOC), then the discharge is carried out at 0.1C for 10 seconds, the recording end voltage V1 and the discharge at 1C for 1s are carried out, and the recording end voltage V2 is recorded;
DCR calculation formula: dcr= (V1-V2)/(1C-0.1C).
Table 2 results of performance test of the batteries of examples and comparative examples
Figure BDA0004141957300000091
From comparison of the test results of comparative examples 1 to 3 and examples 1 to 10 in Table 2, it can be seen that: the introduction of the first additive can effectively improve the high-temperature cycle performance and the safety performance of the lithium ion battery and reduce the interface impedance of the battery; the first additive can improve the high-temperature cycle performance and DCR performance of the battery in a proper addition amount range, and when the additive is excessively added, the performance improvement trend of the battery is slowed down or even the degradation trend appears, and the electronic conductivity and the ionic conductivity of the lithium ion battery are degraded due to the increase of the addition amount and the increase of the interface polarization; compared with the traditional nitrile HTCN, the first additive obviously reduces DCR, is beneficial to improving quick charge low impedance, and simultaneously, the thermal shock performance of the first additive is obviously improved compared with HTCN; in addition, the addition of the first additive also improves the thermal shock performance of the battery, and as the amount of the additive increases, the thermal shock performance of the battery improves more significantly.
Moreover, the synergistic effect of the first additive and the second additive is better, presumably because the first additive has a higher LUMO orbit, the reduction resistance of the anode is improved, the interfacial film formed on the surface of the anode in the first charge and discharge process has low stability and poor performance, when the second additive is synergistic with the second additive, the second additive can generate stable SEI on the surface of the anode in advance, the first additive regenerates into an interfacial film with low impedance and improved stability, and therefore, the thermal shock performance is improved, and meanwhile, the better cycle performance and DCR performance are obtained.
In conclusion, the safe and low-impedance electrolyte and the lithium ion battery provided by the invention have the advantages of improving the high-temperature cycle performance of the battery and showing extremely high application value.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. An electrolyte comprising an electrolyte salt, an organic solvent and a functional additive, the functional additive comprising a first additive which is a phosphazene compound containing an unsaturated bond containing at least one nitrile group (-c≡n) and a phosphorus-carbon double bond (c=p), the nitrile group being directly linked to the phosphorus-carbon double bond.
2. The electrolyte according to claim 1, wherein the phosphazene compound containing an unsaturated bond contains two nitrile groups and a phosphorus-carbon double bond, and the nitrile groups are directly connected to carbon atoms in the phosphorus-carbon double bond.
3. The electrolyte of claim 1 or 2, wherein the first additive comprises at least one of the compounds of formula I:
Figure FDA0004141957290000011
wherein R1, R2 and R3 are the same or different and are independently selected from H, halogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkenyloxy; if substituted, the substituent is halogen, alkyl or cyano.
4. The electrolyte according to claim 3, wherein R1, R2 and R3 are identical or different and are selected independently of one another from H, halogen, substituted or unsubstituted C 1-12 Alkyl, substituted or unsubstituted C 1-12 Alkoxy, substituted or unsubstituted C 2-12 Alkenyl, substituted or unsubstituted C 2-12 An alkenyloxy group; in the case of substitution, the substituents are halogen, C 1-12 Alkyl or cyano radicals。
5. The electrolyte of claim 4, wherein the first additive comprises at least one of the following compounds A1-A4:
Figure FDA0004141957290000021
6. electrolyte according to any one of claims 1-5, characterized in that the first additive is present in an amount of 0.1-10 wt%, preferably 0.5-3 wt%, based on the total mass of the electrolyte.
7. The electrolyte of any one of claims 1-6 wherein the functional additive further comprises a second additive comprising at least one of fluoroethylene carbonate (FEC), 1, 3-Propane Sultone (PS), vinyl sulfate (DTD), propylene Sultone (PST), maleic anhydride, citraconic anhydride, succinic anhydride, succinonitrile (SN), malononitrile (ADN), ethylene glycol bis (propionitrile) ether (EGBE), hexane dinitrile (HTCN).
8. Electrolyte according to claim 7, characterized in that the second additive is present in an amount of 0.1-15 wt%, preferably 5-13 wt%, based on the total mass of the electrolyte.
9. A battery comprising the electrolyte of any one of claims 1-8.
10. The battery of claim 9, further comprising a positive electrode sheet comprising a positive electrode active material, a negative electrode sheet comprising a negative electrode active material;
the negative electrode active material includes nano silicon (Si), silicon oxygen (SiO) x (0<x<2) Silicon carbon, artificial graphite, natural graphite,At least one of mesophase carbon microspheres, hard carbon, soft carbon, lithium metal and lithium titanate.
CN202310292219.2A 2023-03-23 2023-03-23 Electrolyte and battery comprising same Pending CN116387620A (en)

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