CN117551055A - Electrolyte additive, preparation method thereof, nonaqueous electrolyte and alkali metal battery - Google Patents

Electrolyte additive, preparation method thereof, nonaqueous electrolyte and alkali metal battery Download PDF

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CN117551055A
CN117551055A CN202311510421.4A CN202311510421A CN117551055A CN 117551055 A CN117551055 A CN 117551055A CN 202311510421 A CN202311510421 A CN 202311510421A CN 117551055 A CN117551055 A CN 117551055A
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electrolyte
lithium
electrolyte additive
sodium
alkali metal
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谢金鑫
毛冲
杨乐文
杨富杰
张彩霞
徐尚杰
戴文梁
戴晓兵
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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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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D291/00—Heterocyclic compounds containing rings having nitrogen, oxygen and sulfur atoms as the only ring hetero atoms
    • C07D291/02—Heterocyclic compounds containing rings having nitrogen, oxygen and sulfur atoms as the only ring hetero atoms not condensed with other rings
    • 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
    • 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
    • H01M10/24—Alkaline accumulators
    • H01M10/26—Selection of materials as 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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  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
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  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Secondary Cells (AREA)

Abstract

The invention provides an electrolyte additive, a preparation method thereof, a nonaqueous electrolyte and an alkali metal battery. The electrolyte additive of the invention has a structure shown in a formula I, wherein A is + Is an alkali metal ion. The electrolyte additive is of an oxathiamine alkali metal salt structure, and in the structure, in-ring O and N, N and S or O and S have conjugation, an organic SEI film and an inorganic SEI film can be formed at an electrode/electrolyte interface, a double-layer SEI film formed by the organic SEI film and the inorganic SEI film has a synergistic effect, so that growth of metal dendrites can be effectively inhibited, and cycle performance of an alkali metal battery is improved.

Description

Electrolyte additive, preparation method thereof, nonaqueous electrolyte and alkali metal battery
Technical Field
The invention relates to the technical field of batteries, in particular to an electrolyte additive and a preparation method thereof, a nonaqueous electrolyte and an alkali metal battery.
Background
At present, lithium ion batteries are widely applied to technical products such as automobiles, mobile phones and the like. The commercial lithium ion battery mainly uses graphite as a negative electrode material, the capacity of the commercial lithium ion battery is close to the theoretical value (372 mAh/g) of the graphite, and the capacity of the lithium ion battery is difficult to be improved by treating the graphite. In order to obtain a lithium ion battery having a high capacity, a metal material having a high storage capacity characteristic by an alloying reaction with lithium, such as silicon (4200 mAh/g) and tin (990 mAh/g), is used as a negative electrode active material. However, when metals such as silicon and tin are used as the anode active material, the volume thereof expands to about 4 times during charge alloying with lithium, and is re-contracted during discharge. Since a large volume change of the electrode assembly repeatedly occurs during charge/discharge, the active material is gradually micronized and falls off from the electrode, and thus the capacity is rapidly reduced, so that it is difficult to secure stability and reliability, and thus commercialization fails. Compared with the above cathode active materials, alkali metals such as lithium metal, sodium metal and potassium metal have higher specific capacity, especially lithium metal, with theoretical specific capacity up to 3860mAh/g and electrode potential as low as-3.04V (relative toH 2 /H + ) Therefore, the development of an alkali metal battery using lithium metal as a negative electrode has attracted attention from researchers again. However, the barrier to further development of alkali metal batteries is mainly in two aspects (1) alkali metal batteries tend to generate dendrites, such as lithium dendrites, during cycling, which tend to puncture the separator film of the battery, resulting in a short circuit in the battery; (2) Dendrite surface area is big, the activity is high, easily with electrolyte violent reaction, leads to metal surface SEI membrane (interface film) to lasting reorganization, consumes electrolyte and active metal, still leads to circulation efficiency to reduce, shortens battery cycle life. Therefore, how to effectively improve the surface properties of metal electrodes and inhibit the formation of metal dendrites is an important point to be solved for further development of alkali metal batteries
Therefore, there is an urgent need for an electrolyte additive, a method of preparing the same, a nonaqueous electrolyte, and an alkali metal cell to solve the above problems.
Disclosure of Invention
The invention aims to provide an electrolyte additive and a preparation method thereof, wherein the electrolyte additive can be effectively synthesized by the preparation method, and the electrolyte additive can be applied to non-aqueous electrolyte of an alkali metal battery to effectively inhibit the growth of metal dendrites, so that the capacity and the cycle performance of the alkali metal battery are improved.
In order to achieve the above object, the first aspect of the present invention provides an electrolyte additive having a structure represented by formula one:
wherein A is + Is an alkali metal ion.
Compared with the prior art, the electrolyte additive of the invention is an oxathiolane imine alkali metal salt structure compound, the compound has conjugation between in-situ O and N, N and S or between O and S, and can form an organic SEI film with better stability by reaction at the electrode/electrolyte interface, and simultaneously O-S-N-A groups are deposited at the electrode/electrolyte interface to form A film rich in A 3 N，AN x O y ，AS x O y Inorganic SEI films of the composition. The double-layer SEI film formed by the organic SEI film and the inorganic SEI film has a synergistic effect, can effectively inhibit the growth of metal dendrites and improve the cycle performance of an alkali metal battery, so that the advantage of high energy density of an alkali metal cathode can be ensured to be exerted.
The second aspect of the present invention provides a method for preparing the electrolyte additive, comprising the steps of:
s1, chlorosulfonyl isocyanate reacts with ethylene glycol to generate oxathiolimine compounds;
and S2, carrying out substitution reaction on the oxathiolane imine compound and a metal source.
Compared with the prior art, the invention uses chlorosulfonyl isocyanate and ethylene glycol as raw materials to react to prepare an intermediate product with oxathiolimine compounds, and then the intermediate product is subjected to substitution reaction with a metal source to prepare the oxathiolimine alkali metal salt.
Specifically, in the step S1, the reaction process of chlorosulfonyl isocyanate and ethylene glycol may be represented by a reaction formula one, and the obtained product is an oxathiamine compound, which is denoted as an intermediate a:
as a preferred technical scheme, the metal source is selected from any one of lithium hydroxide, lithium carbonate, lithium methoxide, lithium ethoxide, sodium hydroxide, sodium carbonate, sodium methoxide and sodium ethoxide.
Specifically, in the step S2, the metal source is selected from lithium hydroxide, lithium carbonate, lithium methoxide and lithium ethoxide, the reaction process between the intermediate a and the metal source may be represented by the reaction formula two, and the obtained product is the electrolyte additive, and the electrolyte additive is a lithium oxathiamine salt, which is denoted as a compound 1.
Specifically, in the step S2, the metal source is selected from sodium hydroxide, sodium carbonate, sodium methoxide and sodium ethoxide, the reaction process between the intermediate a and the metal source may be represented by the following reaction formula three, and the obtained product is the electrolyte additive, and the electrolyte additive is oxathiamine sodium salt, which is denoted as compound 2.
As a preferred technical scheme, the molar ratio of the chlorosulfonyl isocyanate to the ethylene glycol is 1:1-2, specifically but not limited to 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.5, 1:1.7, 1:1.8, 1:1.9, 1:2, and the molar ratio of the oxathiamine compound to the metal source is 1:1-2, specifically but not limited to 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.5, 1:1.7, 1:1.8, 1:1.9, 1:2.
As a preferred technical scheme, S1 comprises dropwise adding chlorosulfonyl isocyanate into a toluene solution of ethylene glycol at 0 ℃, heating to 120-140 ℃ after dropwise adding, carrying out reflux reaction for 10-15 h, and carrying out aftertreatment to obtain the oxathiolimine compound. As an example, the temperature is raised to 130 ℃ after the completion of the dropwise addition, and the reaction is refluxed for 12 hours.
Specifically, the post-treatment comprises washing, extraction, drying, concentration, separation and purification. As an example, the washing is washing with a saturated sodium chloride solution; the extraction is carried out by adopting dichloromethane; the drying is to adopt anhydrous magnesium sulfate to dry the substance after the extraction and liquid separation; the concentration is reduced pressure concentration by adopting a rotary evaporator; the separation and purification are carried out by column chromatography.
As a preferred technical scheme, the S2 comprises the oxathiamine compound and the metal source, wherein the oxathiamine compound and the metal source react in absolute ethyl alcohol for 10-14 h at the temperature of 0 ℃, and the oxathiamine alkali metal salt is obtained through post-treatment. As an example, the reaction time is 12h.
Specifically, the post-treatment includes concentration and recrystallization, and the concentration is, as an example, concentration of the reaction liquid under reduced pressure using a rotary evaporator; the recrystallization is to recrystallize the concentrated solution by methylene dichloride.
The third aspect of the invention provides a nonaqueous electrolyte, which comprises a nonaqueous solvent, an electrolyte salt, and further comprises the electrolyte additive or the electrolyte additive prepared by the preparation method, wherein the mass percentage of the electrolyte additive in the nonaqueous electrolyte is 0.01% -2.00%, specifically but not limited to 0.01%, 0.05%, 0.10%, 0.50%, 1.00%, 1.20%, 1.40%, 1.60%, 1.80% and 2.00%.
As a preferred technical scheme, the electrolyte salt is any one of lithium salt and sodium salt, and the mass percentage of the electrolyte salt in the nonaqueous electrolyte solution is 8% -14%, specifically but not limited to 8%, 9%, 10%, 11%, 12%, 12.5%, 13%, 13.5% and 14%.
Specifically, the electrolyte salt corresponds to the electrolyte additive, which is, as an example, a lithium salt, and the electrolyte additive adopts compound 1; the electrolyte salt is sodium salt, and the electrolyte additive adopts a compound 2.
As a preferred embodiment, the lithium salt is, in particular but not limited to, lithium hexafluorophosphate (LiPF 6 ) Lithium hexafluoroarsenate (LiAsF) 6 ) Lithium tetrafluoroborate (LiBF) 4 ) Lithium perchlorate (LiClO) 4 ) Lithium hexafluoroantimonate (LiSbF) 6 ) Lithium difluorophosphate (LiPF) 2 O 2 ) One or more of lithium bis (oxalato) borate (LiBOB), lithium difluoro (lidadiob) borate, lithium 4, 5-dicyano-2-trifluoromethylimidazole (lidati) and lithium bis (fluorosulfonyl) imide (LiFSI).
As a preferred embodiment, the sodium salt is sodium hexafluorophosphate (NaPF) 6 ) Sodium tetrafluoroborate (NaBF) 4 ) Sodium perchlorate (NaClO) 4 ) Sodium hexafluoroarsenate (NaAsF) 6 ) Sodium hexafluoroantimonate (NaSbF) 6 ) Sodium difluorophosphate (NaPF) 2 O 2 ) Sodium 4, 5-dicyano-2-trifluoromethylimidazole (NaDTI), sodium bis (oxalato) borate (NaBOB), sodium difluoro (oxalato) borate (N)aDFOB) and sodium bis-fluorosulfonimide (NaFSI).
As a preferred technical scheme, the nonaqueous electrolyte further comprises an auxiliary agent, wherein the auxiliary agent comprises at least one of Vinylene Carbonate (VC), vinyl Ethylene Carbonate (VEC), ethylene Sulfinate (ES), 1, 3-propane sultone (1, 3-PS) and ethylene sulfonate (DTD). Vinyl Ethylene Carbonate (VEC) is preferred, and the VEC has a very low LUMO level (-0.82 eV) and can be reduced and decomposed preferentially on the surface of an alkali metal negative electrode to form a polycarbonate-rich SEI film. And the polycarbonate substance has cohesiveness and flexibility, can help the SEI film adapt to the stress caused by the volume change of the alkali metal cathode, and improves the stability of the SEI film.
As a preferred technical scheme, the mass percentage of the auxiliary agent in the nonaqueous electrolyte is 0.1% -5%, and is specifically but not limited to 0.1%, 0.2%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5% and 5.0%.
As a preferred technical scheme, the nonaqueous solvent is at least one of chain carbonate, cyclic carbonate, carboxylic ester and lactone. Preferably, the nonaqueous organic solvent is a mixture of the chain carbonate and the cyclic carbonate.
Specifically, the chain carbonate may be at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethylmethyl carbonate (EMC), methylpropyl carbonate (PMC), and ethylpropyl carbonate (PEC). By way of example, the chain carbonate may be, but is not limited to, any one or a combination of any of ethylene carbonate (PC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) to achieve a more stable cycle performance.
In particular, the cyclic carbonate may be at least one of Ethylene Carbonate (EC), propylene Carbonate (PC), fluoroethylene carbonate (FEC), butylene carbonate and pentylene carbonate, preferably fluoroethylene carbonate (FEC), which is advantageous for improving the cycle performance of the battery, probably because the introduction of fluoroethylene carbonate FEC molecules having a higher affinity for metal ions participates in the metal ion solvation shell layer, thereby reducing the metal ion desolvation energy barrier and thus reducing the polarization during the metal ion deposition and desolvation process. Meanwhile, the FEC molecules coordinated with the metal ions are preferentially decomposed on the metal surface to form an SEI film rich in fluoride salt, so that the diffusion energy barrier of the metal ions in the SEI film can be reduced, and the metal is induced to be uniformly deposited.
Specifically, the carboxylic acid ester may be at least one of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.
Specifically, the lactone may be at least one of gamma-butyrolactone, gamma-valerolactone, gamma-caprolactone, o-valerolactone and e-caprolactone.
The fourth aspect of the invention provides an alkali metal battery comprising a positive electrode material and a negative electrode material, and further comprising the above-described nonaqueous electrolyte.
As a preferred technical scheme, the negative electrode material is lithium alloy or lithium metal, and the positive electrode material is lithium cobaltate material, lithium iron phosphate material, nickel cobalt manganese oxide or nickel cobalt aluminum oxide. The lithium cobalt oxide material is lithium cobalt oxide or doped and coated modified lithium cobalt oxide, the lithium iron phosphate material is lithium iron phosphate or doped and coated modified lithium iron phosphate, and the chemical formula of the nickel cobalt manganese oxide is LiNi x Co y M (1-x-y-z) O 2 The chemical formula of the nickel cobalt aluminum oxide is LiNi x Co y Al z N (1-x-y-z) O 2 Wherein M is at least one of Mg, cu, zn, A, sn, B, ga, cr, sr, V and Ti, N is at least one of Mn, mg, cu, zn, sn, B, ga, cr, sr, V and Ti, 0.ltoreq.1, 0<y<1，0<z<1, x+y+z is less than or equal to 1. When the negative electrode material is sodium metal or sodium alloy, the positive electrode material is a composite metal oxide similar to the positive electrode of a lithium metal battery. Of course, the positive electrode material may be other materials capable of generating ion deintercalation with sodium ions.
Detailed Description
For a better description of the objects, technical solutions and advantageous effects of the present invention, the present invention 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 invention and should not be taken as limiting the present invention.
The invention may be carried out under conventional conditions or conditions recommended by the manufacturer, and the reagents or apparatus used may be conventional products available commercially without specifying the manufacturer.
First part
This section provides an electrolyte additive having a structure represented by formula one:
wherein A is + Is Li + Or Na (or) + 。
The preparation method of the electrolyte additive comprises the following steps:
s1, adding 20g of ethylene glycol into a dry 500mL three-neck flask, adding 150g of toluene serving as a solvent, placing the flask in a water bath at 0 ℃, dropwise adding 46g of chlorosulfonyl isocyanate into the flask, heating to 130 ℃ after the dropwise adding is finished to enable a reaction system to continuously reflux and react for 12 hours, washing the reaction system with saturated sodium chloride solution after the reaction is finished, extracting with dichloromethane, drying the separated solution with anhydrous magnesium sulfate, concentrating, and separating and purifying by a column chromatography mode to obtain 10g of oxathiamine compounds;
s2 10g of the intermediate and 1.4g of anhydrous lithium hydroxide (or 2.4g of anhydrous sodium hydroxide) were added to a dry 500ml three-necked flask, 100g of anhydrous ethanol was added as a solvent, and the reaction system was allowed to react in a water bath at 0℃for 12 hours. After the reaction is finished, the reaction solution is concentrated, methylene dichloride serving as a recrystallization solvent is added into the reaction solution, and the reaction mixture is filtered to obtain a target product. Wherein A is + Is Li + (i.e., the metal source is anhydrous lithium hydroxide) to yield 8.1g of the product as compound 1; a is that + Is Na (Na) + (i.e., anhydrous sodium hydroxide as the metal source) to yield 8.6g of the productCompound 2. Compound 1 and compound 2 are both white solid, and the result of nuclear magnetic resonance hydrogen spectrum is 1 H NMR (60 mhz, d-DMSO) delta 4.38 (t, j=9.6 hz, 2H), 3.81 (t, j=9.5 hz, 2H). The structures of compound 1 and compound 2 are shown below:
second part
This section is the use of electrolyte additive compound 1 of example 1 in a nonaqueous electrolyte of a lithium metal battery. The following will specifically describe the conditions for the preparation of the electrolyte of group 1 of this section, the preparation of the positive electrode, the preparation of the separator, the preparation of the negative electrode, the preparation of the lithium metal battery, and the test of the cycle performance.
(1) Preparation of electrolyte
Moisture content under argon atmosphere<In a vacuum glove box of 1ppm, methyl ethyl carbonate (EMC) and fluoroethylene carbonate (FEC) are mixed according to the weight ratio of EMC: fec=2:3 followed by 0.5g of compound 1, after dissolution and thorough stirring, 12.5g of lithium hexafluorophosphate (LiPF 6 ) And (5) uniformly mixing to obtain the electrolyte.
(2) Preparation of the Positive electrode
Lithium cobaltate LiCoO 2 The adhesive PVDF and the conductive agent SuperP are mixed according to the mass ratio of 95:1:4, uniformly mixing to prepare lithium metal 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) Preparation of separator
Polyethylene (PE) having a thickness of about 15 μm was used as the separator.
(4) Preparation of negative electrode
And compounding metal lithium onto a current collector copper foil with the thickness of about 10 mu m by a physical rolling method, regulating the pressure of a roller to cover lithium on two sides of the copper current collector, and controlling the thickness of the covered lithium to be about 35 mu m to obtain the lithium-copper composite strip negative electrode. Then after cutting pieces and slitting, the materials are placed in a glove box with dry argon atmosphere for storage.
(5) Preparation of lithium metal batteries
And stacking the positive plate, the isolating film and the lithium copper composite band negative plate in sequence, and then stacking according to the requirement. And (3) after welding the tab, placing the tab in an aluminum plastic film of an external package of the battery, injecting the prepared electrolyte into the dried bare cell, sequentially carrying out the working procedures of vacuum packaging, standing, formation (0.05C constant current is charged to 3.6V, then 0.1C constant current is charged to 3.9V), shaping, capacity testing and the like, and finally obtaining the 1Ah soft package lithium metal battery.
(6) Cycle performance
The lithium metal battery was charged and discharged at 25℃once at 0.5C/0.5C (the discharge capacity of the battery was C) 0 ) The upper limit voltage was 4.55V, and then 0.5C/0.5C charge and discharge was performed for 300 weeks under normal temperature conditions (the battery discharge capacity was C) 1 ) The capacity retention was calculated according to the following formula:
capacity retention= (C 1 /C 0 )×100％
The electrolyte formulations and cycle performance test results of groups 2 to 9 are shown in table 1, and the method of preparing the electrolyte, preparing the battery, and testing the cycle performance is the same as that of group 1.
TABLE 1
As can be seen from table 1, the lithium metal battery including the electrolyte additive compound 1 of the present invention has more excellent cycle performance.
Third part
This section is the use of electrolyte additive compound 2 prepared in example 1 in the nonaqueous electrolyte of sodium metal batteries. The following will specifically describe the conditions for the preparation of the group 1 electrolyte, the preparation of the positive electrode, the preparation of the separator, the preparation of the negative electrode, the preparation of the sodium metal battery, and the test of the cycle performance in this section.
(1) Preparation of electrolyte
Moisture content under argon atmosphere<In a vacuum glove box at 1ppm, ethyl methyl carbonate (EMC) Fluoroethylene carbonate (FEC) with weight ratio EMC: fec=2:3 followed by 0.5g of compound 2, after dissolution and thorough stirring, 12.5g of sodium hexafluorophosphate (NaPF 6 ) And (5) uniformly mixing to obtain the electrolyte.
(2) Preparation of the Positive electrode
Sodium cobaltate NaCoO 2 The adhesive PVDF and the conductive agent SuperP are mixed according to the mass ratio of 95:1:4, uniformly mixing to prepare sodium metal 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) Preparation of separator
Polyethylene (PE) having a thickness of about 15 μm was used as the separator.
(4) Preparation of negative electrode
And compounding metal sodium onto a current collector copper foil with the thickness of about 10 mu m by a physical rolling method, regulating the pressure of a roller to cover sodium on two sides of the copper current collector, and controlling the thickness of the covered sodium to be about 35 mu m to obtain the sodium-copper composite belt cathode. Then after cutting pieces and slitting, the materials are placed in a glove box with dry argon atmosphere for storage.
(5) Preparation of sodium metal battery
And stacking the positive plate, the isolating film and the sodium-copper composite belt negative plate in sequence, and then stacking according to the requirement. And (3) after welding the tab, placing the tab in an aluminum plastic film of an external package of the battery, injecting the prepared electrolyte into the dried bare cell, sequentially carrying out the working procedures of vacuum packaging, standing, formation (0.05C constant current is charged to 3.6V, then 0.1C constant current is charged to 3.9V), shaping, capacity testing and the like, and finally obtaining the soft package sodium metal battery with 1 Ah.
(6) Cycle performance
The sodium metal battery was charged and discharged at 25℃once at 0.5C/0.5C (the discharge capacity of the battery was C) 0 ) The upper limit voltage was 4.55V, and then 0.5C/0.5C charge and discharge was performed for 300 weeks under normal temperature conditions (the battery discharge capacity was C) 1 ) The capacity retention was calculated according to the following formula:
capacity retention= (C 1 /C 0 )×100％
The electrolyte formulations and cycle performance test results of groups 2 to 9 are shown in Table 2, and the method of preparing the electrolyte, preparing the battery, and testing the cycle performance are the same as those of group 1.
TABLE 2
As can be seen from table 2, the sodium metal battery including the electrolyte additive compound 2 of the present invention has more excellent cycle performance.
In conclusion, the electrolyte prepared by the invention is added and applied to an alkali metal battery, so that the cycle performance of alkali metal can be effectively improved, probably because the electrolyte additive is an oxathiolimine alkali metal salt structural compound, and the ring O and N, N and S or O and S of the compound have conjugation, react at the electrode/electrolyte interface to form an organic SEI film with better stability, and simultaneously O-S-N-A groups (A is alkali metal) are deposited at the electrode/electrolyte interface to form A film rich in A 3 N，AN x O y ，AS x O y Inorganic SEI films of the composition. The double-layer SEI film formed by the organic SEI film and the inorganic SEI film has a synergistic effect, can effectively inhibit the growth of metal dendrites, improves the cycle performance of an alkali metal battery, and shows that the electrolyte additive has a better application prospect in the alkali metal ion battery.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the present invention can be modified or substituted without departing from the spirit and scope of the technical solution of the present invention.

Claims (10)

1. An electrolyte additive characterized by having a structure represented by formula one:
wherein A is + Is an alkali metal ion.
2. A method of preparing the electrolyte additive of claim 1, comprising the steps of:
s1, chlorosulfonyl isocyanate reacts with ethylene glycol to generate oxathiolimine compounds;
and S2, carrying out substitution reaction on the oxathiolane imine compound and a metal source.
3. The method for producing an electrolyte additive according to claim 2, wherein the metal source is selected from any one of lithium hydroxide, lithium carbonate, lithium methoxide, lithium ethoxide, sodium hydroxide, sodium carbonate, sodium methoxide, and sodium ethoxide.
4. The method for preparing an electrolyte additive according to claim 2, wherein the molar ratio of the chlorosulfonyl isocyanate to the ethylene glycol is 1:1-2, and the molar ratio of the oxathiamine compound to the metal source is 1:1-2.
5. The method for preparing the electrolyte additive according to claim 2, wherein the step S1 comprises dropwise adding the chlorosulfonyl isocyanate into a toluene solution of ethylene glycol at 0 ℃, heating to 120-140 ℃ after the dropwise adding, carrying out reflux reaction for 10-15 h, and carrying out aftertreatment to obtain the oxathiolimine compound.
6. The method for preparing the electrolyte additive according to claim 2, wherein the S2 comprises the step of reacting the oxathiolimine compound and the metal source in absolute ethanol at 0 ℃ for 10-14 h, and then performing post-treatment to obtain the electrolyte additive.
7. The nonaqueous electrolyte comprises a nonaqueous solvent and electrolyte salt, and is characterized by further comprising the electrolyte additive according to claim 1 or the electrolyte additive prepared by the preparation method according to any one of claims 2-6, wherein the mass percentage of the electrolyte additive in the nonaqueous electrolyte is 0.01% -2.00%.
8. The nonaqueous electrolytic solution according to claim 7, wherein the electrolyte salt is any one of a lithium salt and a sodium salt, and the mass percentage of the electrolyte salt in the nonaqueous electrolytic solution is 8% to 14%.
9. The nonaqueous electrolytic solution of claim 7, further comprising an auxiliary agent comprising at least one of vinylene carbonate, vinyl ethylene carbonate, vinyl sulfinate, 1, 3-propane sultone and vinyl sulfonate.
10. An alkali metal battery comprising a positive electrode material and a negative electrode material, characterized by further comprising the nonaqueous electrolytic solution according to any one of claims 7 to 9.
CN202311510421.4A 2023-11-14 2023-11-14 Electrolyte additive, preparation method thereof, nonaqueous electrolyte and alkali metal battery Pending CN117551055A (en)

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