CN118040059A - Electrolyte and application thereof - Google Patents

Electrolyte and application thereof Download PDF

Info

Publication number
CN118040059A
CN118040059A CN202410441664.5A CN202410441664A CN118040059A CN 118040059 A CN118040059 A CN 118040059A CN 202410441664 A CN202410441664 A CN 202410441664A CN 118040059 A CN118040059 A CN 118040059A
Authority
CN
China
Prior art keywords
electrolyte
substituted
unsubstituted
cyano
additive
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.)
Granted
Application number
CN202410441664.5A
Other languages
Chinese (zh)
Other versions
CN118040059B (en
Inventor
金飘
章毓坚
崔屹
刘婵
侯敏
曹辉
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.)
Shanghai Ruipu Energy Co Ltd
Rept Battero Energy Co Ltd
Original Assignee
Shanghai Ruipu Energy Co Ltd
Rept Battero Energy 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 Shanghai Ruipu Energy Co Ltd, Rept Battero Energy Co Ltd filed Critical Shanghai Ruipu Energy Co Ltd
Priority to CN202410441664.5A priority Critical patent/CN118040059B/en
Publication of CN118040059A publication Critical patent/CN118040059A/en
Application granted granted Critical
Publication of CN118040059B publication Critical patent/CN118040059B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • 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

Landscapes

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

Abstract

The invention relates to an electrolyte and application thereof, wherein the electrolyte comprises a combination of a solvent, lithium salt and an additive; the additive comprises a combination of a sulfate additive, lithium tetrafluoroborate and fluoroethylene carbonate; the sulfate additive comprises at least one compound with a structure shown in the following formula I. The electrolyte provided by the invention can effectively inhibit gas production of the battery, and simultaneously can ensure that the battery has good high-temperature cycle performance, high-temperature storage performance and low-temperature multiplying power performance.

Description

Electrolyte and application thereof
Technical Field
The invention belongs to the technical field of secondary batteries, and particularly relates to electrolyte and application thereof.
Background
The silicon-based negative electrode has huge volume change and low self conductivity in the charge and discharge process, so that the battery capacity is quickly attenuated, the silicon-based negative electrode material is unstable in structure and easy to react with electrolyte chemically and electrochemically, and as the silicon content is increased, the silicon-based negative electrode expands more obviously, the electrode material is damaged and electrolyte is decomposed more seriously, so that the battery performance is attenuated more rapidly.
The electrolyte typically consists of a solvent, a lithium salt, and additives, wherein the additives are closely related to the performance of the battery. CN116613302a discloses a lithium ion secondary battery comprising a negative electrode sheet and an electrolyte, the electrolyte comprising fluoroethylene carbonate (FEC) which is an important negative electrode film forming additive for silicon systems, but FEC is unstable, structurally, FEC is reduced at the negative electrode, loses F at the negative electrode, and decomposes into a substance having a structure similar to Vinylene Carbonate (VC), which migrates to the positive electrode where decomposition (VC-like) occurs at a higher voltage, generating gas. In addition, the SEI film formed by FEC is unstable and is easy to break during the silicon expansion process, and the SEI film needs to be repaired by continuously consuming film forming additives.
Silicon itself has low conductivity and poor dynamic properties, resulting in poor rate capability of the battery. Conventional high temperature additives, such as PST, tripropylester phosphate (TPP), VES, 2-fluoropyridine, etc., are mostly high in resistance, and can hinder lithium ion transmission, resulting in deterioration of the silicon system cycle performance.
Therefore, there is a need for developing an electrolyte solution that can suppress the generation of gas in a battery and that can give the battery a good combination of high-temperature cycle performance, high-temperature storage performance and low-temperature rate performance.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide the electrolyte and the application thereof, and through screening and compounding of each component of the electrolyte, the gas production of the battery can be reduced, and meanwhile, the battery has good high-temperature cycle performance, high-temperature storage performance and low-temperature multiplying power performance.
To achieve the purpose, the invention adopts the following technical scheme:
In a first aspect, the present invention provides an electrolyte comprising a combination of a solvent, a lithium salt, and an additive; the additive comprises a combination of a sulfate additive, lithium tetrafluoroborate and fluoroethylene carbonate; the sulfate additive comprises at least one compound with a structure shown as the following formula I:
A formula I;
Wherein R 1、R2、R3、R4 is each independently selected from any one of a hydrogen atom, halogen, cyano, substituted or unsubstituted C1-C6 straight or branched alkyl, substituted or unsubstituted C1-C6 alkoxy, L 1 -OC (=O) -, substituted or unsubstituted C2-C6 alkenyl, substituted or unsubstituted C2-C6 alkynyl, L 2-C(=O)-L3 -, C6-C12 aryl, C3-C6 tertiary amino, C3-C6 siloxane, C3-C12 heteroaryl, amide, CN-O-or isocyanate group.
L 1、L2 is independently selected from any one of C1-C5 straight chain or branched alkyl.
L 3 is selected from any one of C1-C5 straight chain or branched chain alkylene.
The substituted groups in R 1、R2、R3、R4 are each independently selected from at least one of halogen, cyano, isocyanate, C3-C6 tertiary amino, amide, C3-C6 silyl or C3-C6 siloxane groups.
In the invention, the sulfate additive with the structure shown in the formula I firstly reacts with the surface of the negative electrode to generate an inner SEI (solid electrolyte interphase) with sulfate-rich inorganic matters and alkyl organic matters, and further, lithium tetrafluoroborate (LiBF 4) induces fluoroethylene carbonate (FEC) to defluorinate to form an outer SEI containing Li xBFy or Li xBOyFz, high-elasticity polymer (VC) and high-content LiF. The SEI film with the alternation of the organic matters and the inorganic matters shows remarkably enhanced mechanical stability and ion conductivity, which can effectively relieve the volume change of the Si negative electrode and promote the stable circulation of the lithium ion battery. The stable SEI film can adapt to the volume change of silicon and keep the stability of the electrode structure. Meanwhile, the existence of LiBF 4 can promote the film formation of FEC, reduce the migration of FEC to the positive electrode, inhibit the generation of HF, reduce the generation of decomposition products capable of generating gas, and further inhibit the generation of gas, thereby maintaining the good high-temperature cycle performance and storage performance of the battery; in addition, the sulfate additive with the structure of formula I is polycyclic sulfate, has stable structure, can form an interfacial film rich in sulfate components at the positive electrode, and can effectively inhibit gas production; the lithium tetrafluoroborate can form a film on the positive electrode to protect the positive electrode; however, the polycyclic sulfate has a slightly complex structure and slightly poor low-temperature performance, and the battery can give consideration to the low-temperature rate performance through the coordination of lithium tetrafluoroborate which has better stability at high temperature and better low-temperature performance.
In the present invention, each of the C1-C6 may be independently C1, C2, C3, C4, C5 or C6.
The C6-C12 may each independently be C6, C7, C8, C9, C10, C11 or C12.
The C3-C12 may each independently be C3, C4, C5, C6, C7, C8, C9, C10, C11 or C12.
The C3-C6 may each independently be C3, C4, C5, C6.
The C1-C5 may each independently be C1, C2, C3, C4, C5.
The halogen in the invention comprises F, cl, br or I.
The C1-C6 straight or branched alkyl group illustratively includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl and the like.
The C1-C6 alkoxy is a monovalent group formed by linking O with a straight or branched alkyl group as set forth above.
The C6-C12 aryl group comprises phenyl, biphenyl, naphthyl and the like.
The C3-C12 heteroaryl group includes pyridyl, pyrazinyl, imidazolyl, furyl, thienyl and the like.
The C3-C6 siloxane groups illustratively include trimethylsiloxane groups, triethoxysiloxane groups, and the like.
The following is a preferred technical scheme of the present invention, but not a limitation of the technical scheme provided by the present invention, and the following preferred technical scheme can better achieve and achieve the objects and advantages of the present invention.
As a preferred embodiment, any one of R 1 and R 3 is selected from any one of cyano, substituted or unsubstituted C1-C6 alkoxy, CN-O-, substituted or unsubstituted C2-C6 alkenyl, substituted or unsubstituted C2-C6 alkynyl, and the other is a hydrogen atom; the substituted group is selected from at least one of cyano, isocyanate or C3-C6 siloxane groups.
Unsaturated substituents such as cyano, alkenyl and alkynyl can enhance the reducibility of sulfate additives, which is advantageous for forming a stable SEI film at the anode.
Preferably, any one of R 1 and R 3 is selected from any one of cyano, CN-O-, vinyl or ethynyl, and the other is a hydrogen atom.
Preferably, any one of R 2 and R 4 is selected from any one of halogen, cyano, substituted or unsubstituted C1-C6 alkoxy, CN-O-, substituted or unsubstituted C1-C6 linear or branched alkyl, C3-C6 siloxane or isocyanate groups, the other is hydrogen atom; the substituted group is selected from at least one of cyano, isocyanate or C3-C6 siloxane groups.
Acid-removing and water-removing groups such as cyano, C3-C6 siloxane groups and isocyanate groups are beneficial to stabilizing the positive electrode (with acid-removing and water-removing and positive electrode film-forming functions), enhancing the stability of the positive electrode and effectively inhibiting the gas production of the positive electrode.
Preferably, any one of R 2 and R 4 is selected from any one of fluorine, cyano, CN-O-, methyl, methoxy, -O-Si (CH 3)3 or isocyanate), and the other is a hydrogen atom.
Preferably, the sulfate additive is selected from any one or a combination of at least two of the following compounds:
；
Preferably, the sulfate additive is 0.1-2% (e.g., 0.2%, 0.3%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 1.9%, etc.), and more preferably 0.1-1% by mass of the electrolyte.
Preferably, the mass percentage of lithium tetrafluoroborate in the electrolyte is 0.1 to 2% (e.g., 0.2%, 0.3%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 1.9%, etc.), and more preferably 0.1 to 1%.
Preferably, the mass percentage of fluoroethylene carbonate in the electrolyte is 2-20%, for example, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20% and the like.
Preferably, the solvent comprises a combination of at least two of Ethylene Carbonate (EC), propylene Carbonate (PC), ethylmethyl carbonate (EMC), dimethyl carbonate (DMC) or diethyl carbonate (DEC).
Preferably, the mass percentage of the solvent in the electrolyte is 60-80%, for example, 60%, 61%, 62%, 63%, 65%, 66%, 68%, 69%, 70%, 72%, 74%, 76%, 78% or 80% and the like.
Preferably, the lithium salt comprises a combination of LiFSI and LiPF 6.
Preferably, the mass percentage of LiFSI in the electrolyte is 3-9.5%, for example, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5% or 9%, etc.
Preferably, the mass percentage of the lithium salt in the electrolyte is 7-16%, for example, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or 16% or the like.
In a second aspect, the present invention provides a secondary battery comprising a positive electrode sheet, a silicon-containing negative electrode sheet and an electrolyte as described in the first aspect.
Preferably, the positive electrode active material of the positive electrode sheet is one or more of lithium nickel manganese cobalt ternary material, lithium cobalt oxide (LiCoO 2), lithium iron phosphate (LiFePO 4), lithium manganese iron phosphate (LiMnFePO 4) and doping and/or cladding modified compounds thereof.
Preferably, the negative active material of the silicon-containing negative electrode sheet includes a combination of graphite and a silicon-carbon composite material.
Preferably, the mass percentage of the silicon-carbon composite material in the anode active material is 5-50%, for example, may be 5.5%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 25%, 30%, 35%, 40%, 50%, etc.
Preferably, the silicon-carbon composite material contains 5-30% of silicon by mass percent.
Compared with the prior art, the invention has the following beneficial effects:
The electrolyte provided by the invention can inhibit gas production of the battery, and simultaneously can ensure that the battery has good high-temperature cycle performance, high-temperature storage performance and low-temperature rate performance, wherein the gas production of the battery after high-temperature storage is 1.5-2.9mL, the number of high-temperature cycles is 1565-2302, the capacity retention rate after high-temperature storage is 88.25-95.32%, and the capacity retention rate in a low-temperature rate test is 75.17-81.62%.
Detailed Description
To facilitate understanding of the present invention, examples are set forth below. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
The sources of some of the components in the examples and comparative examples are shown in Table 1:
TABLE 1
Example 1
An electrolyte in which the solvent is 12wt.% EC,12wt.% PC,53.5wt.% EMC, the lithium salt is 13.5wt.% (wherein LiFSI is 5wt.%, liPF 6 is 8.5 wt.%), the compound i-5 is 0.5wt.%, the lithium tetrafluoroborate is 0.5wt.%, and the FEC is 8wt.%, based on 100wt.% of the mass of the electrolyte.
Example 2
An electrolyte in which the solvent is 16wt.% EC,8wt.% PC,50.9wt.% EMC, the lithium salt is 15.5wt.% (wherein LiFSI is 3wt.%, liPF 6 is 12.5 wt.%), the compound i-8 is 0.3wt.%, the lithium tetrafluoroborate is 0.3wt.%, and the FEC is 9wt.%, based on 100wt.% of the mass of the electrolyte.
Example 3
An electrolyte in which the solvent was 4.2% wt. ec,16.9% wt. pc, 55.4% wt. EMC, lithium salt was 14.5% wt. (where LiFSI was 7%, liPF 6 was 7.5% wt.), compound i-13 was 1.0% wt., lithium tetrafluoroborate was 1.0% wt., and FEC was 7% wt., based on 100% wt. of the electrolyte.
Example 4
An electrolyte was different from example 1 only in that the compound I-5 was replaced with the compound I-6 in equal amounts, and the remaining components and amounts were the same as in example 1.
Example 5
An electrolyte was different from example 1 only in that the compound I-5 was replaced with the compound I-18 in equal amounts, and the remaining components and amounts were the same as in example 1.
Example 6
An electrolyte was different from example 1 only in that the compound I-5 was replaced with the compound I-4 in equal amounts, and the remaining components and amounts were the same as in example 1.
Example 7
An electrolyte was different from example 1 only in that the same amount of Compound I-5 was replaced with Compound I-21, and the remaining components and amounts were the same as those of example 1.
Example 8
An electrolyte in which the solvent is 12wt.% EC,12wt.% PC,53.95wt.% EMC, the lithium salt is 13.5wt.% (where LiFSI is 5%, liPF 6 is 8.5 wt.%), the compound i-5 is 0.05wt.%, the lithium tetrafluoroborate is 0.5wt.%, and the FEC is 8wt.%, based on 100wt.% of the mass of the electrolyte.
Example 9
An electrolyte in which the solvent is 12% wt. ec,12% wt. pc, 52.8% wt. EMC, the lithium salt is 13.5wt.% (wherein LiFSI is 5%, liPF 6 is 8.5 wt.%) compound i-5 is 1.2wt.%, lithium tetrafluoroborate is 0.5wt.%, and FEC is 8wt.%, based on 100wt.% of the electrolyte.
Example 10
An electrolyte in which the solvent was 12% wt. ec,12% wt. pc, 51.8% wt. EMC, the lithium salt was 13.5wt.% (wherein LiFSI was 5%, liPF 6 was 8.5 wt.%) and the compound i-5 was 2.2wt.%, lithium tetrafluoroborate was 0.5wt.%, and FEC was 8wt.%, based on 100wt.% of the electrolyte.
Example 11
An electrolyte was different from example 1 only in that the compound I-5 was replaced with the compound I-1 in equal amounts, and the remaining components and amounts were the same as in example 1.
Example 12
An electrolyte was different from example 1 only in that the compound I-5 was replaced with the compound I-19 in equal amounts, and the remaining components and amounts were the same as in example 1.
Comparative example 1
An electrolyte was different from example 1 only in that lithium tetrafluoroborate was replaced with lithium difluorooxalato borate in equal amounts, and the remaining components and amounts were the same as in example 1.
Comparative example 2
An electrolyte, based on 100wt.% of the electrolyte, in which the solvent is 12wt.% EC,12%wt.PC,54wt wt.% EMC, the lithium salt is 13.5wt.% (where LiFSI is 5%, liPF 6 is 8.5 wt.%), compound i-5 is 0.5wt.%, and FEC is 8wt.%, i.e., no lithium tetrafluoroborate is added.
Comparative example 3
An electrolyte, based on 100wt.% of the electrolyte, the electrolyte contains 12wt.% of ec,12wt.% of PC,54wt.% of EMC, 13.5wt.% of lithium salt (wherein LiFSI is 5%, liPF 6 is 8.5 wt.%), 0.5wt.% of lithium tetrafluoroborate and 8wt.% of FEC, i.e. no sulfate additive having the structure shown in formula i is added.
Comparative example 4
An electrolyte in which the solvent was 12% by weight ec, 12% by weight PC, 54.5% by weight EMC, 13.5% by weight lithium salt (wherein LiFSI was 5%, liPF 6 was 8.5% by weight) and FEC was 8% by weight, based on 100% by weight of the electrolyte.
Application example 1
A secondary battery comprising a positive electrode sheet, a silicon-containing negative electrode sheet, and the electrolyte provided in example 1;
The preparation method of the positive plate comprises the following steps:
The positive electrode material comprises, based on 100wt.% of the total mass of the positive electrode material, 97.5wt.% of LiNi 90Co5.5Mn3.5Al1O2 positive electrode active substance, 1.5wt.% of Super P-conductive agent and 1.0wt.% of polyvinylidene fluoride binder; mixing the components, adding an N-methyl pyrrolidone solvent, uniformly mixing to obtain positive electrode slurry, coating the positive electrode slurry on the surface of a carbon-coated aluminum foil, drying, and slicing to obtain a positive electrode plate;
The preparation method of the silicon-containing negative plate comprises the following steps:
Mixing graphite, a silicon-carbon composite material (purchased from Lanxi Zhiden New energy materials Co., ltd., model S0310), a Super P conductive agent, polyacrylic acid and styrene-butadiene latex according to a mass ratio of 85.6:9.5:1.2:3:0.7, adding deionized water, uniformly stirring to obtain negative electrode slurry, coating the negative electrode slurry on the surface of a copper foil, drying, and slicing to obtain a negative electrode plate;
The positive electrode sheet, the silicon-containing negative electrode sheet, the electrolyte provided in example 1 and the separator were assembled into a secondary battery, and the secondary battery was then formed at 45 ℃ (the formation step was that 0.05C was charged to 3.0V, 0.1C was charged to 3.4V, and then 0.2C was charged to 3.7V), and after the formation was completed, aging and capacity division were performed to obtain the secondary battery.
Application examples 2 to 12 and application comparative examples 1 to 4
A secondary battery differing from application example 1 only in the kind of the positive electrode active material or the electrolyte, and the other component amounts, process parameters and steps are the same as those of application example 1.
The compositions of the secondary batteries provided in application examples 1 to 12 and application comparative examples 1 to 4 are shown in the following table 2:
TABLE 2
Performance testing
(1) High temperature cycle performance:
Charging the secondary battery into a 45 ℃ incubator at constant current of 1C to 4.2V, charging at constant voltage of 4.2V to 0.05C, and discharging the secondary battery at constant current of 1C to 2.5V, wherein the charging and discharging cycle process is recorded, and the initial discharge capacity is recorded; capacity retention= (remaining discharge capacity/initial discharge capacity) ×100%, the number of cycles at which the secondary battery capacity retention rate was 80% was recorded;
(2) High temperature storage performance:
Charging the secondary battery to 4.2V at 25 ℃ with constant current of 1C, charging to 0.05C at constant voltage of 4.2V, and then discharging to 2.5V with constant current of 1C, which is recorded as a charge-discharge cycle process, recording initial discharge capacity C 0, placing the secondary battery into a 60 ℃ oven after full charge again, standing for 2h at normal temperature after 30 days of storage, discharging to 2.8V with 1C, recording the residual discharge capacity of the battery at the moment, and calculating to obtain final battery capacity retention rate, wherein the battery capacity retention rate= (residual discharge capacity/initial discharge capacity) ×100%;
(3) Gas production after high temperature storage:
The method for testing the volume of the secondary battery comprises the following steps: placing a beaker containing deionized water on an electronic balance, recording the indication m 1 of the electronic balance at the moment, fixing a secondary battery in mid-air by using a clamp of an iron stand, slowly immersing the secondary battery in the beaker containing ionized water downwards until the secondary battery is completely immersed in the deionized water, recording the indication m 2 of the electronic balance at the moment, and calculating the battery volume V= (m 2-m1)×g/(ρH2O multiplied by P) according to the formula mg=ρ H2O VP. Wherein ρ H2O is the density of deionized water, g is the gravity coefficient, P is a standard atmospheric pressure, V is the volume of the secondary battery;
By adopting the volume testing method, the battery volume V 1 of the secondary battery before high-temperature storage is calculated, then the volume V 2 of the secondary battery after high-temperature storage is calculated, and the gas yield of the battery after high-temperature storage=V 2-V1;
The method for high-temperature storage is the same as the method (2);
(4) Low temperature rate capability:
The secondary battery was charged to 4.2V at 25 ℃ with a constant current of 1C, charged to 0.05C at a constant voltage of 4.2V, and then discharged to 2.8V with a constant current of 1C, which is recorded as a charge-discharge cycle process, the initial discharge capacity was recorded, the lithium ion battery was placed in an oven at-10 ℃ after full charge again, left standing for 10 hours, discharged to 2.5V at 2C, the remaining discharge capacity of the battery at this time was recorded and the final battery capacity retention rate was calculated to be the battery capacity retention rate= (remaining discharge capacity/initial discharge capacity) ×100%.
The secondary batteries provided in application examples 1 to 12 and application comparative examples 1 to 4 were subjected to performance tests according to the above-described test methods, and the test results are shown in table 3:
TABLE 3 Table 3
It can be seen from application examples 1-7 that in different systems, the positive electrode active material has good effect of selecting proper substituent groups on the substituent groups of the additive in the electrolyte, for example, cyano groups have remarkable effect of complexing transition metal stable positive electrodes in a LiCoO 2 system, isocyanate groups can be subjected to electrochemical polymerization in LiMn 0.5Fe0.5PO4, formation of SEI films is promoted, acid removal and water removal are achieved, and the effect is good. The unsaturated substituent groups (cyano, alkenyl and alkynyl) can enhance the reducibility of the additive, are favorable for forming a stable SEI film on a negative electrode, and the acid removal and dehydration base (cyano, siloxane base and isocyanate base) is favorable for stabilizing a positive electrode (with acid removal and dehydration and positive electrode film forming functions), enhancing the stability of the positive electrode and effectively inhibiting the gas production of the positive electrode.
As can be seen from application examples 1 and 5, in the structure of the compound i-18, the halogen substituent can participate in the film formation of the negative electrode, so as to form a low-impedance SEI film containing LiF, which is favorable for lithium ion transmission, and the low-temperature rate performance of the battery is slightly improved, however, the halogen substituent is unstable at high temperature and is easy to defluorinate at high temperature to generate HF, so that the high-temperature cycle performance and the high-temperature storage performance of the battery are deteriorated.
As can be seen from application examples 1 and 6, the structure of the compound i-4 has excessive double bond substituents, and although the positive electrode is formed with a film, the effect of suppressing gas generation is remarkable, the negative electrode is liable to form a thicker SEI film, the internal resistance of the battery is increased, the lithium ion transmission is difficult, and the cycle and low-temperature rate performance are also reduced.
As can be seen from application examples 1 and 7, the trimethylsiloxane substituent and LiBF 4 in the structures of the compounds I-21 can form a film at the positive electrode and the negative electrode, and the negative electrode SEI film contains a compound with a unique structure of B-O-Si, so that the stability of an interface can be maintained in a circulating process and the continuous growth of the SEI film caused by the volume expansion of Si can be inhibited. However, too many trimethylsiloxane substituents tend to form a film on the positive electrode, which results in too thick a film on the positive electrode, increases the internal resistance of the battery, and makes lithium ion transport difficult and deteriorates the high-temperature cycle performance.
As can be seen from application examples 1 and 8-10, the electrolyte has too little additive, and the formed interface film is unstable and has poor effect; excessive additives can cause thicker film formation at the interfaces of the positive electrode and the negative electrode, have larger impedance, and are unfavorable for lithium ion transmission, so that the cycle performance of the battery is reduced.
As can be seen from application examples 1 and 11-12, the compound i-1 has poor overall reducibility, cannot form stable SEI on the negative electrode, does not contain a group for stabilizing the positive electrode, cannot sufficiently protect the positive electrode, and thus has slightly poor performance; the structure of the compound I-19 contains more F atoms, and the compound I-19 is easy to generate HF at high temperature due to the more F atoms, so that the dissolution of the transition metal element of the positive electrode and the decline of the battery capacity are caused.
As can be seen from application examples 1 to 10 and comparative examples 1 to 4, the introduction of lithium tetrafluoroborate and the sulfate-based additive having the structure of formula I can generate a low-resistance and firm SEI film containing B, S, F components at the negative electrode, so that the low-temperature performance of the battery system is significantly improved, the reaction of FEC with the negative electrode can be suppressed, the decomposition of FEC is reduced, and thus the decomposition products that can generate gas are not generated, and further the generation of gas is suppressed. In addition, liBF 4 is stable at high temperature, and the sulfate additive with the structure of formula I can form stable CEI containing inorganic salt components at the positive electrode, so that side reaction between the positive electrode and electrolyte is reduced, gas generation is inhibited, and high-temperature performance of the battery is further improved.
The applicant states that the detailed process equipment and process flows of the present invention are described by the above examples, but the present invention is not limited to, i.e., does not mean that the present invention must be practiced in dependence upon, the above detailed process equipment and process flows. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of raw materials for the product of the present invention, addition of auxiliary components, selection of specific modes, etc., falls within the scope of the present invention and the scope of disclosure.

Claims (10)

1. An electrolyte comprising a combination of a solvent, a lithium salt, and an additive;
The additive comprises a combination of a sulfate additive, lithium tetrafluoroborate and fluoroethylene carbonate;
the sulfate additive comprises at least one compound with a structure shown as the following formula I:
；
I
Wherein each R 1、R2、R3、R4 is independently selected from any one of a hydrogen atom, halogen, cyano, substituted or unsubstituted C1-C6 straight or branched alkyl, substituted or unsubstituted C1-C6 alkoxy, L 1 -OC (=O) -, substituted or unsubstituted C2-C6 alkenyl, substituted or unsubstituted C2-C6 alkynyl, L 2-C(=O)-L3 -, C6-C12 aryl, C3-C6 tertiary amino, C3-C6 siloxane, C3-C12 heteroaryl, amide, CN-O-, or isocyanate group;
l 1、L2 is independently selected from any one of C1-C5 straight chain or branched alkyl;
L 3 is selected from any one of C1-C5 straight chain or branched chain alkylene;
The substituted groups in R 1、R2、R3、R4 are each independently selected from at least one of halogen, cyano, isocyanate, C3-C6 tertiary amino, amide, C3-C6 silyl or C3-C6 siloxane groups.
2. The electrolyte according to claim 1, wherein any one of R 1 and R 3 is selected from any one of cyano, substituted or unsubstituted C1-C6 alkoxy, CN-O-, substituted or unsubstituted C2-C6 alkenyl, substituted or unsubstituted C2-C6 alkynyl, and the other is a hydrogen atom;
The substituted group is selected from at least one of cyano, isocyanate or C3-C6 siloxane groups.
3. The electrolyte according to claim 1, wherein any one of R 2 and R 4 is selected from any one of halogen, cyano, substituted or unsubstituted C1-C6 alkoxy, CN-O-, substituted or unsubstituted C1-C6 linear or branched alkyl, C3-C6 siloxane group, or isocyanate group, the other being a hydrogen atom;
The substituted group is selected from at least one of cyano, isocyanate or C3-C6 siloxane groups.
4. The electrolyte of claim 1, wherein the sulfate-based additive is selected from any one or a combination of at least two of the following compounds:
；；
；
；；；；。
5. the electrolyte according to claim 1, wherein the mass percentage of the sulfate-based additive in the electrolyte is 0.1-2%.
6. The electrolyte according to claim 1, wherein the mass percentage of lithium tetrafluoroborate in the electrolyte is 0.1-2%;
the mass percentage of fluoroethylene carbonate in the electrolyte is 2-20%.
7. The electrolyte of claim 1, wherein the solvent comprises a combination of at least two of ethylene carbonate, propylene carbonate, ethylmethyl carbonate, dimethyl carbonate, or diethyl carbonate;
The mass percentage of the solvent in the electrolyte is 60-80%.
8. The electrolyte of claim 1 wherein the lithium salt comprises a combination of LiFSI and LiPF 6;
the mass percentage of LiFSI in the electrolyte is 3-9.5%;
The mass percentage of the lithium salt in the electrolyte is 7-16%.
9. A secondary battery comprising a positive electrode sheet, a silicon-containing negative electrode sheet, and the electrolyte according to any one of claims 1 to 8.
10. The secondary battery according to claim 9, wherein the negative electrode active material of the silicon-containing negative electrode sheet comprises a combination of graphite and a silicon-carbon composite material.
CN202410441664.5A 2024-04-12 2024-04-12 Electrolyte and application thereof Active CN118040059B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202410441664.5A CN118040059B (en) 2024-04-12 2024-04-12 Electrolyte and application thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202410441664.5A CN118040059B (en) 2024-04-12 2024-04-12 Electrolyte and application thereof

Publications (2)

Publication Number Publication Date
CN118040059A true CN118040059A (en) 2024-05-14
CN118040059B CN118040059B (en) 2024-07-02

Family

ID=90997286

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202410441664.5A Active CN118040059B (en) 2024-04-12 2024-04-12 Electrolyte and application thereof

Country Status (1)

Country Link
CN (1) CN118040059B (en)

Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102646847A (en) * 2012-02-17 2012-08-22 深圳新宙邦科技股份有限公司 Lithium ion secondary battery and electrolyte thereof
CN104600364A (en) * 2015-02-06 2015-05-06 宁德新能源科技有限公司 Electrolyte and lithium ion battery applying same
JP2015195135A (en) * 2014-03-31 2015-11-05 三井化学株式会社 Nonaqueous electrolyte for battery and lithium secondary battery
CN105655642A (en) * 2016-03-30 2016-06-08 宁德时代新能源科技股份有限公司 Electrolyte and high-nickel anode lithium ion battery containing same
CN107017433A (en) * 2016-01-28 2017-08-04 宁德新能源科技有限公司 Nonaqueous electrolytic solution and lithium ion battery
JP2018092778A (en) * 2016-12-02 2018-06-14 日立化成株式会社 Lithium ion secondary battery
CN109755635A (en) * 2019-01-18 2019-05-14 杉杉新材料（衢州）有限公司 A kind of battery electrolyte additive that taking into account high temperature performance, electrolyte and nickelic ternary lithium ion battery
CN110336076A (en) * 2019-06-19 2019-10-15 东莞东阳光科研发有限公司 Lithium-ion battery electrolytes and lithium ion battery
CN110386916A (en) * 2019-07-23 2019-10-29 常熟市常吉化工有限公司 A kind of synthetic method of cyclic sulfates
CN110854433A (en) * 2019-11-15 2020-02-28 欣旺达电动汽车电池有限公司 Electrolyte and electrochemical device
CN111834671A (en) * 2020-07-27 2020-10-27 香河昆仑化学制品有限公司 Electrolyte suitable for silicon-carbon cathode and lithium ion battery
EP3872914A1 (en) * 2020-02-28 2021-09-01 SK Innovation Co., Ltd. Electrolyte for lithium secondary battery and lithium secondary battery including the same
CN114597492A (en) * 2021-04-12 2022-06-07 深圳市研一新材料有限责任公司 Nonaqueous electrolyte solution and lithium ion battery using same
WO2023088234A1 (en) * 2021-11-19 2023-05-25 浙江省化工研究院有限公司 Lithium ion battery electrolyte solution and lithium ion battery
CN117790898A (en) * 2022-09-29 2024-03-29 浙江蓝天环保高科技股份有限公司 Lithium ion battery electrolyte and lithium ion battery containing same

Patent Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102646847A (en) * 2012-02-17 2012-08-22 深圳新宙邦科技股份有限公司 Lithium ion secondary battery and electrolyte thereof
JP2015195135A (en) * 2014-03-31 2015-11-05 三井化学株式会社 Nonaqueous electrolyte for battery and lithium secondary battery
CN104600364A (en) * 2015-02-06 2015-05-06 宁德新能源科技有限公司 Electrolyte and lithium ion battery applying same
CN107017433A (en) * 2016-01-28 2017-08-04 宁德新能源科技有限公司 Nonaqueous electrolytic solution and lithium ion battery
CN105655642A (en) * 2016-03-30 2016-06-08 宁德时代新能源科技股份有限公司 Electrolyte and high-nickel anode lithium ion battery containing same
JP2018092778A (en) * 2016-12-02 2018-06-14 日立化成株式会社 Lithium ion secondary battery
CN109755635A (en) * 2019-01-18 2019-05-14 杉杉新材料（衢州）有限公司 A kind of battery electrolyte additive that taking into account high temperature performance, electrolyte and nickelic ternary lithium ion battery
CN110336076A (en) * 2019-06-19 2019-10-15 东莞东阳光科研发有限公司 Lithium-ion battery electrolytes and lithium ion battery
CN110386916A (en) * 2019-07-23 2019-10-29 常熟市常吉化工有限公司 A kind of synthetic method of cyclic sulfates
CN110854433A (en) * 2019-11-15 2020-02-28 欣旺达电动汽车电池有限公司 Electrolyte and electrochemical device
EP3872914A1 (en) * 2020-02-28 2021-09-01 SK Innovation Co., Ltd. Electrolyte for lithium secondary battery and lithium secondary battery including the same
CN111834671A (en) * 2020-07-27 2020-10-27 香河昆仑化学制品有限公司 Electrolyte suitable for silicon-carbon cathode and lithium ion battery
CN114597492A (en) * 2021-04-12 2022-06-07 深圳市研一新材料有限责任公司 Nonaqueous electrolyte solution and lithium ion battery using same
WO2023088234A1 (en) * 2021-11-19 2023-05-25 浙江省化工研究院有限公司 Lithium ion battery electrolyte solution and lithium ion battery
CN117790898A (en) * 2022-09-29 2024-03-29 浙江蓝天环保高科技股份有限公司 Lithium ion battery electrolyte and lithium ion battery containing same

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
HENRIK GULYAS 等: "A new route for the synthesis of amphiphilic and water-soluble ligands: monoand di-tertiary phosphines having an alkylene sulfate chain", CHEM. COMMUN., 1 January 1997 (1997-01-01), pages 2385 - 2386 *
JUN MING等: ""New Insight on the Role of Electrolyte Additives in Rechargeable Lithium Ion Batteries"", 《ACS ENERGY LETT.》, vol. 4, 8 October 2019 (2019-10-08), pages 2613 *
张晓妍等: "动力电池电解液用添加剂的研究进展", 储能科学与技术, vol. 7, no. 3, 31 May 2018 (2018-05-31), pages 405 - 417 *
陈人杰等: "有机硼酸锂盐及亚硫酸酯类功能电解质材料", 化学进展, vol. 23, no. 2, 31 March 2011 (2011-03-31), pages 382 - 389 *

Also Published As

Publication number Publication date
CN118040059B (en) 2024-07-02

Similar Documents

Publication Publication Date Title
CN109921092B (en) Non-aqueous electrolyte of silicon-based negative electrode lithium ion battery and silicon-based negative electrode lithium ion battery containing electrolyte
CN109888389B (en) Ternary lithium ion battery non-aqueous electrolyte and high-nickel ternary lithium ion battery containing electrolyte
CN109193029B (en) High-nickel ternary lithium ion battery non-aqueous electrolyte and high-nickel ternary lithium ion battery containing electrolyte
CN109860709B (en) Electrolyte for improving low-temperature performance of lithium ion battery and lithium ion battery containing electrolyte
CN111244546B (en) Electrolyte for lithium ion battery suitable for quick charging and lithium ion battery
CN110391457B (en) Electrolyte and lithium ion battery
CN113517470A (en) High-nickel high-voltage ternary lithium ion battery non-aqueous electrolyte and lithium ion battery
CN111525192A (en) Lithium ion battery non-aqueous electrolyte and lithium ion battery
CN114512721B (en) Non-aqueous electrolyte of lithium ion battery and lithium ion battery
CN111029655A (en) Lithium ion battery electrolyte and lithium ion battery containing same
CN112448033A (en) High-voltage lithium ion battery electrolyte and long-cycle-life high-voltage lithium ion battery
CN112216862A (en) High-nickel ternary lithium ion battery electrolyte and ternary lithium ion battery
CN112290089A (en) Lithium ion battery non-aqueous electrolyte solution and lithium ion battery
CN111668551B (en) Electrolyte matched with silicon-carbon negative electrode material lithium ion battery
CN116344937A (en) Lithium ion battery and electrolyte thereof
CN108206299B (en) Lithium ion battery and electrolyte thereof
CN111106387A (en) Electrolyte and lithium ion battery
CN112310475A (en) Lithium ion battery non-aqueous electrolyte and lithium ion battery
CN112290090A (en) High-nickel ternary lithium ion battery non-aqueous electrolyte and battery containing electrolyte
CN114039094A (en) Non-aqueous electrolyte of lithium ion battery and lithium ion battery
CN112271335A (en) Electrolyte of lithium ion battery suitable for high-nickel cathode material and lithium ion battery
CN118040059B (en) Electrolyte and application thereof
CN115832434A (en) Lithium ion battery electrolyte and lithium ion battery containing same
CN111048836B (en) Electrolyte and lithium ion battery
CN115775918A (en) High-nickel ternary lithium ion battery non-aqueous electrolyte and lithium ion battery containing electrolyte

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant