CN118146250A - Polysiloxane boric acid pinacol ester compound, preparation method thereof, electrolyte, lithium ion battery and power utilization device - Google Patents

Polysiloxane boric acid pinacol ester compound, preparation method thereof, electrolyte, lithium ion battery and power utilization device Download PDF

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Publication number
CN118146250A
CN118146250A CN202410271784.5A CN202410271784A CN118146250A CN 118146250 A CN118146250 A CN 118146250A CN 202410271784 A CN202410271784 A CN 202410271784A CN 118146250 A CN118146250 A CN 118146250A
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China
Prior art keywords
electrolyte
pinacol ester
acid pinacol
lithium
polysiloxaneboronic
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CN202410271784.5A
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Inventor
赵志刚
蒋世用
何海平
张灵志
骆萱
陈程
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Gree Electric Appliances Inc of Zhuhai
Guangzhou Institute of Energy Conversion of CAS
Gree Altairnano New Energy Inc
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Gree Electric Appliances Inc of Zhuhai
Guangzhou Institute of Energy Conversion of CAS
Gree Altairnano New Energy Inc
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Priority to CN202410271784.5A priority Critical patent/CN118146250A/en
Publication of CN118146250A publication Critical patent/CN118146250A/en
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    • 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

Abstract

The application relates to the field of electrochemical energy storage, and discloses a polysiloxaneboronic acid pinacol ester compound, a preparation method thereof, electrolyte, a lithium ion battery and an electric device. The polysiloxaneboronic acid pinacol ester compound is a structural compound shown in a formula 1 or a formula 2; the polysiloxaneboronic acid pinacol ester compound is used as an electrolyte additive of the lithium ion battery, has the effect that a conventional film forming additive is preferentially oxidized to form a film by an electrolyte solvent, reduces side reaction of an interface between the electrolyte and a positive electrode material, and protects the structural integrity of the positive electrode material; and can effectively inhibit lithium salt in the electrolyte from being hydrolyzed, and effectively improve the cycle life, the multiplying power performance and the specific discharge capacity of the battery.

Description

Polysiloxane boric acid pinacol ester compound, preparation method thereof, electrolyte, lithium ion battery and power utilization device
Technical Field
The application relates to the field of electrochemical energy storage, in particular to a polysiloxaneboronic acid pinacol ester compound, a preparation method thereof, electrolyte, a lithium ion battery and an electric device.
Background
The lithium ion battery has the characteristics of high energy density, long cycle life, wide working temperature range and the like, and is widely applied to specific application scenes such as hybrid electric vehicles, pure electric vehicles, portable equipment, energy storage and the like. In order to adapt to the development of new energy industry and electric automobiles, the lithium ion battery needs to develop towards the direction of long cycle life.
The electrolyte is an indispensable part of the lithium ion battery and is an important bridge for connecting the anode and the cathode to realize ion transmission. The lithium ion battery electrolyte consists of lithium salt (such as lithium hexafluorophosphate and the like) and electrolyte solvent (such as carbonate solvents of dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate and the like). The film forming additive is added in the electrolyte, and the additive can be oxidized to form a film on the surface of the electrode in preference to the solvent of the electrolyte, so that the electrolyte is prevented from directly contacting with the anode material, the electrode material is protected to be stable in structure, and the cycle life of the battery is further prolonged.
However, hydrolysis of lithium salts in the electrolyte can cause the system to produce hydrofluoric acid. On one hand, hydrofluoric acid can corrode the electrode, damage CEI film already formed on the surface of the electrode, influence the stability of the electrode material structure; on the other hand, hydrofluoric acid can generate irreversible chemical reaction with active lithium ions in the battery, and limited active lithium ions in the battery are consumed to generate LiF precipitation, so that the irreversible capacity loss of the battery is increased and the cycle life of the battery is shortened finally.
The conventional film-forming additive generally only performs electrode protection on the surface of the electrode in preference to the film-forming by the solvent oxidation of the electrolyte, and has no definite effect on the hydrolysis of lithium salt in the electrolyte. Therefore, there is a strong need to develop new electrolyte additives for inhibiting the hydrolysis of lithium salts of the electrolyte, thereby stabilizing the structure of the electrolyte and the cathode material and prolonging the cycle life of the lithium ion battery.
Disclosure of Invention
In view of the above, the application aims to provide a polysiloxaneboronic acid pinacol ester compound and a preparation method thereof, so that the polysiloxaneboronic acid pinacol ester compound can inhibit the hydrolysis of lithium salt of electrolyte, effectively improve the cycle life, the rate capability and the specific discharge capacity of a battery, and simultaneously has a film forming function and protects the electrode material structure.
Another object of the present application is to provide an electrolyte, a lithium ion battery and an electric device based on the polysiloxaneboronic acid pinacol ester compound of the present application.
In order to achieve the above object, as a first aspect of the present application, there is provided a polysiloxaneboronic acid pinacol ester compound which is a structural compound represented by formula 1 or formula 2:
Wherein each R 1、R2、R3、R4、R5、R6、R7 is independently selected from the group consisting of a linear or branched alkyl group of C 1-C5, a linear or branched alkoxy group of C 1-C5; n 1 is an integer from 0 to 5, Z is a linear or branched alkylene group of C 1-C5.
Alternatively, the R 1、R2、R3、R4、R5、R6、R7 is independently selected from the group consisting of a linear alkyl group of C 1-C3, a linear alkoxy group of C 1-C3; n 1 is an integer from 1 to 3, Z is a linear or branched alkylene group of C 1-C3.
Further alternatively, the structural compound shown in formula 1 comprises any one or more of the following compounds:
Further alternatively, the structural compound represented by formula 2 comprises any one or more of the following compounds:
as a second aspect of the present application, there is provided a method for preparing the polysiloxaneboronic acid pinacol ester compound, comprising:
The polysiloxane and double bond boric acid pinacol ester are subjected to hydrosilation reaction under the catalysis of a catalyst, and the polysiloxane boric acid pinacol ester compound is prepared.
Alternatively, the process may be carried out in a single-stage, the polyalkoxysilahydride is 1,3, 5-heptamethyl trisiloxane or 1,3, 5-heptamethyltrisiloxane; the double bond pinacol borate is vinyl boric acid pinacol ester or propenyl boric acid ortho-di-tertiary alcohol ester.
As a third aspect of the present application, there is provided an electrolyte comprising any one or more of an electrolyte lithium salt, a solvent and the polysiloxaneboronic acid pinacol ester compound of the present application.
Optionally, the electrolyte lithium salt is selected from any one or more of lithium hexafluorophosphate, lithium perchlorate, lithium dioxalate borate, lithium difluorooxalate borate, lithium bistrifluoromethylsulfonimide, lithium bistrifluorosulfonylimide and their corresponding metal sodium salts; the solvent is selected from any one or more of carbonic acid ester solvents.
As a fourth aspect of the present application, there is provided a lithium ion battery comprising the electrolyte according to the present application.
As a fifth aspect of the present application, there is provided an electric device comprising the lithium ion battery of the present application.
The polysiloxaneboronic acid pinacol ester compound is used as an electrolyte additive of the lithium ion battery, has the effect that a conventional film forming additive is preferentially oxidized to form a film by an electrolyte solvent, reduces side reaction of an interface between the electrolyte and a positive electrode material, and protects the structural integrity of the positive electrode material; and can effectively inhibit lithium salt in the electrolyte from being hydrolyzed, and effectively improve the cycle life, the multiplying power performance and the specific discharge capacity of the battery.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a undue limitation;
FIG. 1 shows a nuclear magnetic resonance hydrogen spectrum of a compound of example 1 of the present invention;
FIG. 2 shows a nuclear magnetic resonance spectrum of the compound of example 1 of the present invention;
FIG. 3 shows a nuclear magnetic silica spectrum of the compound of example 1 of the present invention;
FIG. 4 shows a nuclear magnetic resonance boron spectrum of the compound of example 1 of the present invention;
FIG. 5 shows a nuclear magnetic resonance hydrogen spectrum of the compound of example 2 of the present invention;
FIG. 6 shows a nuclear magnetic resonance spectrum of the compound of example 2 of the present invention;
FIG. 7 shows a nuclear magnetic silica spectrum of the compound of example 2 of the present invention;
FIG. 8 shows a nuclear magnetic resonance boron spectrum of the compound of example 2 of the present invention;
FIG. 9 shows a nuclear magnetic resonance hydrogen spectrum of the compound of example 3 of the present invention;
FIG. 10 shows a nuclear magnetic resonance spectrum of the compound of example 3 of the present invention;
FIG. 11 shows a nuclear magnetic silica spectrum of the compound of example 3 of the present invention;
FIG. 12 shows a nuclear magnetic resonance boron spectrum of the compound of example 3 of the present invention;
FIG. 13 shows a comparative hydrolyzability test of different electrolytes; wherein legend example 4 represents the compound of example 1 + LBE301 base electrolyte; comparative example 1 represents an LBE301 base electrolyte;
FIG. 14 shows a linear scan of different electrolytes; wherein legend example 4 represents the compound of example 1 + LBE301 base electrolyte; comparative example 1 represents an LBE301 base electrolyte;
FIG. 15 shows normal temperature cycle performance testing of different LMO/Li batteries; wherein legend example 4 shows a battery using the compound of example 1 + LBE301 base electrolyte; comparative example 1 shows a battery using only LBE301 base electrolyte;
FIG. 16 shows high temperature cycle performance tests for different LMO/Li batteries; wherein legend example 4 shows a battery using the compound of example 1 + LBE301 base electrolyte; comparative example 1 shows a battery using only LBE301 base electrolyte;
FIG. 17 shows high temperature cycle performance tests for different LMO/LTO cells; wherein legend example 4 shows a battery using the compound of example 1 + LBE301 base electrolyte; comparative example 1 shows a battery using only LBE301 base electrolyte;
FIG. 18 shows high temperature rate performance tests for different LMO/Li batteries; wherein legend example 4 shows a battery using the compound of example 1 + LBE301 base electrolyte; comparative example 1 shows a battery using only LBE301 base electrolyte;
FIG. 19 shows impedance testing of different LMO/Li cells; wherein legend example 4 shows a battery using the compound of example 1 + LBE301 base electrolyte; comparative example 1 shows a battery using only LBE301 base electrolyte;
FIG. 20 shows high temperature performance tests of different 2.22Ah-LMO/LTO pouch cells; wherein legend example 4 shows a battery using the compound of example 1 + LBE301 base electrolyte; comparative example 1 shows a battery using only LBE301 base electrolyte.
Detailed Description
The application discloses a polysiloxaneboronic acid pinacol ester compound, a preparation method thereof, electrolyte, a lithium ion battery and an electric device, and the polysiloxaneboronic acid pinacol ester compound can be realized by appropriately improving process parameters by a person skilled in the art based on the content of the polysiloxaneboronic acid pinacol ester compound. It is expressly noted that all such similar substitutions and modifications will be apparent to those skilled in the art, and are deemed to be included in the present application. While the products and processes of the present application have been described in terms of preferred embodiments, it will be apparent to those skilled in the relevant art that the application can be practiced and practiced with modification and alteration and combination of the products and processes described herein without departing from the spirit and scope of the application. It will be apparent that the described embodiments are some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
It should be noted that, in this document, relational terms such as "first" and "second," "step 1" and "step 2," and "(1)" and "(2)" and the like, if any, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Meanwhile, the embodiments of the present application and features in the embodiments may be combined with each other without collision.
In a first aspect of the present application, there is provided a polysiloxaneboronic acid pinacol ester compound which is a structural compound represented by formula 1 or formula 2:
Wherein each R 1、R2、R3、R4、R5、R6、R7 is independently selected from the group consisting of a linear or branched alkyl group of C 1-C5, a linear or branched alkoxy group of C 1-C5; n 1 is an integer from 0 to 5, Z is a linear or branched alkylene group of C 1-C5. The alkylene may be an alkylene group formed by removing two H atoms from the same C atom, or may be an alkylene group formed by removing one H atom from two different C atoms, for example, an alkylene group of C 2, which may have the following two structures:
In certain embodiments of the application, the R 1、R2、R3、R4、R5、R6、R7 is independently selected from the group consisting of C 1-C3 linear alkyl (e.g., methyl, ethyl, n-propyl, etc.), C 1-C3 linear alkoxy (e.g., methoxy, ethoxy, n-propoxy, etc.); n 1 is an integer from 1 to 3 (e.g., 1,2, 3), Z is a straight or branched alkylene group of C 1-C3 (e.g., methylene, ethylene, 1, 2-ethylene, propylene, 1, 2-propylene, 1, 3-propylene, etc.).
In other embodiments of the application, each of said R 1、R2、R3、R4、R5、R6、R7 is selected from methyl; n 1 is 1; z is methylene, ethylene, 1, 2-ethylene, propylene, 1, 2-propylene, 1, 3-propylene.
In certain embodiments of the present application, the structural compound of formula 1 comprises any one or more of the following compounds:
in certain embodiments of the present application, the structural compound of formula 2 comprises any one or more of the following compounds:
In a second aspect of the present application, there is provided a method for preparing the polysiloxaneboronic acid pinacol ester compound, comprising:
The polysiloxane and double bond boric acid pinacol ester are subjected to hydrosilation reaction under the catalysis of a catalyst, and the polysiloxane boric acid pinacol ester compound is prepared.
Wherein, according to the position difference of hydrogen atoms in the polyalkoxysilane, the compounds with the structures of the formula 1 and the formula 2 are synthesized correspondingly, and the reaction routes of the two are respectively as follows:
The catalyst may be selected to catalyze the hydrosilation reaction of a hydrosilylation reaction with an unsaturated olefin, such as transition metal (Pt, pd, rh, ru, ir, etc.) catalysts, including [ RhCl (PPh 3)3 ] and [ { Rh (μ -Cl) (cod) } 2 ], etc., using chloroplatinic acid-isopropanol (1:1 by volume) catalysts or Karstedt's catalysts in certain embodiments of the application, and in other embodiments of the application, the catalyst is added in a molar amount of 0.1 to 1 times the molar amount of the double bond pinacol borate.
In certain embodiments of the application, the hydrosilation reaction is performed under a protective atmosphere, such as an inert gas atmosphere; the hydrosilation reaction temperature is 40-130 ℃, the reaction temperature is higher than 130 ℃, the reaction system temperature is too high, the side reaction is too much to reduce the product yield, the temperature is lower than 40 ℃, the reaction system temperature is too low, and the activation energy required by the reaction cannot be reached despite the catalyst. The reaction time of the hydrosilation reaction is generally 4-24 hours, and the reaction progress can be monitored in real time until the reaction is complete; in the hydrosilation reaction, the reaction mole ratio of the double bond boric acid pinacol ester to the polyalkoxy silane is 1:1.0-1.1.
In certain embodiments of the present application, the polyalkoxysilahydride is 1,3, 5-heptamethyl trisiloxane or 1,3, 5-heptamethyltrisiloxane; the double bond pinacol borate is vinyl boric acid pinacol ester or propenyl boric acid ortho-di-tertiary alcohol ester.
In a third aspect of the present application, there is provided an electrolyte comprising an electrolyte lithium salt, a solvent, a polysiloxaneboronic acid pinacol ester compound of the present application. When the polysiloxaneboronic acid pinacol ester compound is used as an additive, the polysiloxaneboronic acid pinacol ester compound can be oxidized and decomposed in preference to a commercial carbonate solvent, a layer of uniform and compact protective film is formed on the surface of the positive electrode material, the side reaction of an electrolyte and the interface of the positive electrode material is reduced, and the structural integrity of the positive electrode material is protected. Of particular importance, the polysiloxaneboronic acid pinacol ester compound of the present application also inhibits the formation of hydrofluoric acid from lithium salt hydrolysis in the electrolyte, thereby protecting the electrode from structural stability and extending the battery life.
In certain embodiments of the application, the polysiloxaneboronic acid pinacol ester compound is used in an amount of 0.1% to 5% by weight of the total mass of lithium salt and solvent, and the concentration of the lithium salt in the electrolyte is 0.5 to 1.5mol/L.
In certain embodiments of the application, the electrolyte lithium salt is selected from any one or more of lithium hexafluorophosphate (LiPF 6), lithium dioxalate borate (LiBOB), lithium difluorooxalate borate (liodb), lithium perchlorate (LiClO 4), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiFSI), and their corresponding metal sodium salts;
in certain embodiments of the application, the solvent is selected from any one or more of the carbonate solvents. The carbonate solvents include, but are not limited to, ethylene Carbonate (EC), propylene Carbonate (PC), butylene Carbonate (BC), fluoroethylene carbonate (FEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), methylpropyl carbonate (MPC), diphenyl carbonate (DPhC). In other embodiments of the application, the solvent is a mixed solvent of ec+dmc+emc, preferably in a volume ratio of 1:1:1.
In a fourth aspect of the application, there is provided a lithium ion battery comprising the electrolyte of the application. In certain embodiments of the application, the lithium ion battery comprises the electrolyte, a positive electrode sheet, a negative electrode sheet, a separator and a housing. In still other embodiments of the present application, a button cell is provided that includes a negative electrode casing, a negative electrode tab, an electrolyte, a separator, a positive electrode tab, a gasket, a tab, and a positive electrode casing.
In certain embodiments of the present application, the positive electrode sheet comprises a positive electrode active material, a conductive agent, a binder, and a metal foil, and the negative electrode sheet comprises a negative electrode active material, a conductive agent, a binder, and a metal foil; in other embodiments of the application, the positive/negative electrode active material: conductive agent: the mass ratio of the binder is (90-95): 1-5. In still other embodiments of the present application, the positive electrode active material may use lithium iron phosphate (LFP), ternary materials (NMC, NCA), lithium Manganate (LMO), lithium Cobaltate (LCO), etc., the negative electrode active material may use graphite, lithium titanate, metallic lithium, silicon-based negative electrode, etc., the conductive agent is acetylene black (Super P), the binder is polyvinylidene fluoride (PVDF), vinylidene fluoride/hexafluoropropylene copolymer or styrene-butadiene rubber (SBR), the metallic foil is copper foil or aluminum foil, and the separator is selected from polyethylene, polypropylene or a mixture of both having high wettability to an electrolyte.
In a fifth aspect of the present application, there is provided an electric device comprising the lithium ion battery of the present application, which may be various devices driven using lithium ion batteries, including but not limited to electric bicycles, electric vehicles, balance cars, flatcars, aircrafts, lighting equipment, home appliances, and the like.
In each of the comparative experiments provided by the present application, unless otherwise specified, other experimental conditions, materials, etc. were kept consistent to allow for comparability, except for the differences noted in each group. In addition, the materials used in the present application are all commercially available.
The application provides a polysiloxaneboronic acid pinacol ester compound, a preparation method thereof, an electrolyte, a lithium ion battery and an electric device.
Example 1: synthesis of Polysiloxaneboronic acid pinacol ester Compounds HTDBS (Compound of formula 9) and HTDBS2 (Compound of formula 11) in a 100mL three-necked round bottom flask under Ar atmosphere, vinyl boronic acid pinacol ester (25 g,162 mmol) and Karstedt's catalyst (1.2 g,121 mmol) were added slowly dropwise 1,3, 5-heptamethyltrisiloxane (39.8 g,179 mmol), and after the addition was completed, the reaction was carried out at 40℃for 12h to give the crude product. The crude product was subjected to multiple reduced pressure distillations to give the polysiloxaneboronic acid pinacol esters HTDBS and HTDBS2 (1:2 mass ratio of the two) at 110 ℃/1.6 mmHg. HTDBS1 and HTDBS are isomers of each other.
HTDBS1：1H-NMR(400 MHz,CDCl3)δ1.25(s,12H),0.74(m,2H),0.51(m,2H),0.09(s,15H),0.01(s,6H);13C-NMR(100 MHz,CDCl3)δ82.59,25.61,9.94,5.21,1.73,-1.32;29Si-NMR(79 MHz,CDCl3)δ6.64,-20.91;11B-NMR(128 MHz,CDCl3)δ34.37.
HTDBS2：1H-NMR(400 MHz,CDCl3)δ1.23(s,12H),1.02(d,3H),0.31(q,1H),0.10(s,15H),0.05(s,6H);13C-NMR(100 MHz,CDCl3)δ82.31,24.71,8.73,8.21,1.73,-0.71;29Si-NMR(79 MHz,CDCl3)δ6.45,-23.30;11B NMR(128MHz,CDCl3)δ34.37.
The nuclear magnetic 1H-NMR、13C-NMR、29 Si-NMR and 11 B-NMR are shown in FIGS. 1-4.
Example 2: synthesis of Polysiloxaneboronic acid pinacol ester Compound HTDPS (Compound of formula 3) in a 100mL three-necked round bottom flask under Ar atmosphere, propenyl boric acid ortho-di-tert-alcohol ester (16.76 g,0.1 mol), catalytic amount of chloroplatinic acid and isopropanol were added first, 1,3, 5-heptamethyltrisiloxane (22.3 g,0.1 mol) was slowly added dropwise, and after the addition was completed, the reaction was carried out at 70℃for 6 hours to obtain a crude product. The crude product was subjected to multiple reduced pressure distillations to give the polysiloxaneboronic acid pinacol ester (HTDPS), b.p.:118 ℃ C./2.1 mmHg.
HTDPS：1H-NMR(400MHz,CDCl3)δ1.48-1.44(m,2H),1.24(s,12H),0.85-0.82(t,J＝7.6HZ,2H),0.6-0.56(m,2H),0.09(s,9H),0.06(s,6H),0.02(s,6H);13C-NMR(100MHz,CDCl3)δ82.75,24.79,21.53,17.87,15.31,1.78,1.23,0.21;29Si-NMR(79MHz,CDCl3)δ6.53,6.34,-21.79;11B NMR(128MHz,CDCl3)δ34.06.
The nuclear magnetic 1H-NMR、13C-NMR、29 Si-NMR and 11 B-NMR are shown in FIGS. 5-8.
Example 3: synthesis of Polysiloxaneboronic acid pinacol ester Compound HTMDPS (Compound of formula 10) in a 25mL three-necked round bottom flask under Ar atmosphere, acrylic boric acid orthodi-tert-alcohol ester (1.51 g,9 mmol), catalytic amount of chloroplatinic acid and isopropanol were added first, 1,3, 5-heptamethyltrisiloxane (2 g,9 mmol) was slowly added dropwise, and after completion of the dropwise addition, the reaction was carried out at 70℃for 6 hours to obtain a crude product. The crude product was subjected to multiple distillation under reduced pressure to give the polysiloxaneboronic acid ester compound (HTMDPS), b.p. 110 ℃ C./1.43 mmHg.
HTMDPS：1H-NMR(400MHz,CDCl3)δ1.48-1.41(m,2H),1.24(s,12H),0.82(t,J＝7.6Hz,2H),0.52-0.46(m,2H),0.08(s,18H),-0.01(s,3H);13C-NMR(100MHz,CDCl3)δ82.77,24.82,20.77,17.78,1.84,-0.24;29Si-NMR(79MHz,CDCl3)δ6.73,-21.61;11B NMR(128MHz,CDCl3)δ34.07.
The nuclear magnetic 1H-NMR、13C-NMR、29 Si-NMR and 11 B-NMR are shown in FIGS. 9-12.
Example 4: electrolyte, pole piece and buckling preparation
1. Electrolyte solution
The base electrolyte used was LBE301, configured as 1mol/L LiPF 6/EC+DMC+EMC (volume ratio 1:1:1), purchased from Shanghai owl energy technologies Co. And adding the prepared polysiloxaneboronic acid pinacol ester compound serving as an additive into the basic electrolyte according to the mass fraction of 0.5-1%, and fully stirring for later use.
2. Pole piece
Mixing an active material, a conductive agent, a binder, and a solvent, positive/negative electrode active material: conductive agent: the mass ratio of the binder is (90-95): (1-5): (1-5), the slurry is coated on an aluminum foil current collector and dried in an oven to prepare the pole piece. According to the method, a positive pole piece and a negative pole piece are respectively manufactured.
The anode material is LMO; the negative electrode material is lithium titanate; the conductive agent is acetylene black; the binder may be vinylidene fluoride (PVDF) and vinylidene fluoride/hexafluoropropylene copolymers; the solvent is N-methyl pyrrolidone; the separator is made of polyethylene, polypropylene or a mixture of polyethylene and polypropylene with high electrolyte wettability.
3. Buckling assembly
The assembly of the CR2025 button cell was completed in a glove box filled with high purity argon. The method comprises the steps of assembling a negative electrode shell, a negative electrode plate, electrolyte, a diaphragm, electrolyte, a positive electrode plate, a gasket, an elastic piece and a positive electrode shell in sequence. And (3) after the just-packaged battery is placed into the sealed sealing pocket in the glove box, transferring the battery to a manual button cell sealing machine to complete battery packaging. And after the battery is assembled, placing the battery at room temperature of 25 ℃ for 12 hours to obtain the lithium manganate button battery.
Experimental example:
(1) Electrolyte testing
The compound of example 1 + LBE301 base electrolyte and LBE301 base electrolyte were each added with 3000ppmH 2 O and stored at 25 ℃ for three days before nuclear magnetism was measured. The LBE301 base electrolyte (comparative example 1 in the legend) in FIG. 13 clearly shows the signal peaks of the electrolyte hydrolysates PO 2F2-, HF, liF. While the presence of the above three peaks was not observed in the compound of example 1 + LBE301 base electrolyte (illustrated as example 4), it was demonstrated that the polysiloxaneboronic acid pinacol ester compound of the present application was effective in inhibiting the hydrolysis of lithium hexafluorophosphate.
Fig. 14 shows the comparison of the linear scan curves of the electrolyte, and the change of the current curve of the compound of example 1+ LBE301 base electrolyte over that of the LBE301 base electrolyte, shows that the polysiloxaneboronic acid pinacol ester compound can be oxidized and decomposed in advance of the electrolyte, and a protective film is formed on the surface of the positive electrode.
(2) The electrochemical performance of the electricity buckle (illustrated as comparative example 1) made with reference to example 4 using LBE301 base electrolyte as a comparison, and the electricity buckle (illustrated as example 4) made with reference to example 4 using the compound of example 1 of the present application as an additive, were compared as follows:
Fig. 15, 16 and 17 are cyclic tests assembled into CR2025 button LMO/Li half-cells and LMO/LTO full-cells. The button cell is charged and discharged in a new Wei workstation, and the LMO/Li half cell and the LMO/LTO full cell are charged and discharged in the voltage ranges of 3-4.3V and 0.01-3V respectively by using 1C constant current. The initial discharge capacity of the LMO/LTO full cell using the compound of example 1+ LBE301 base electrolyte at a high temperature of 55℃was found to be 137.8mAh/g, which is substantially equivalent to that of the LMO/LTO full cell using the LBE301 base electrolyte alone. However, the capacity retention rate of the LMO/LTO full cell after 300 circles of high temperature 1C is improved to 49.2% compared with 34.3% of the comparative example, and the capacity retention rate is improved by about 15%.
Fig. 18 is a high temperature rate performance test of CR2025 button LMO/Li half-cell at high temperature, the cell using the compound of example 1+ LBE301 base electrolyte showed higher discharge capacity at higher rates 5C, 10C than the cell using LBE301 base electrolyte alone, demonstrating better rate performance.
Fig. 19 is a graph showing the impedance test (300 turns) of a CR2025 button LMO/Li half-cell, which shows that the cell using the compound of example 1 + LBE301 base electrolyte significantly reduces the surface film impedance of the positive electrode material.
FIG. 20 is a graph showing the capacity retention of a 2.22Ah pouch cell assembled from LMO/LTO material, cycled 420 cycles at a current density of 55℃ -2C, with a capacity retention of 90.6% for the LMO/LTO pouch cell using the compound of example 1+ LBE301 base electrolyte, significantly higher than 83.9% for the cell using the LBE301 base electrolyte alone.
By combining the performance tests in the aspects, the polysiloxaneboronic acid pinacol ester compound can be used as an additive of an electrolyte, can inhibit lithium salt in the electrolyte besides the conventional functions of film formation and electrode structure stability protection, prevent the formed CEI film from being damaged by hydrofluoric acid generated by hydrolysis, and effectively improve the cycle life, the rate capability and the specific discharge capacity of a battery.
The foregoing is only a specific embodiment of the application to enable those skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A polysiloxaneboronic acid pinacol ester compound characterized in that it is a structural compound represented by formula 1 or formula 2:
Wherein each R 1、R2、R3、R4、R5、R6、R7 is independently selected from the group consisting of a linear or branched alkyl group of C 1-C5, a linear or branched alkoxy group of C 1-C5; n 1 is an integer from 0 to 5, Z is a linear or branched alkylene group of C 1-C5.
2. The polysiloxaneboronic acid pinacol ester compound according to claim 1, wherein R 1、R2、R3、R4、R5、R6、R7 is independently selected from the group consisting of C 1-C3 straight chain alkyl, C 1-C3 straight chain alkoxy; n 1 is an integer from 1 to 3, Z is a linear or branched alkylene group of C 1-C3.
3. The polysiloxaneboronic acid pinacol ester compound according to claim 1, wherein the structural compound represented by formula 1 comprises any one or more of the following compounds:
4. The polysiloxaneboronic acid pinacol ester compound according to claim 1, wherein the structural compound represented by formula 2 comprises any one or more of the following compounds:
5. A process for the preparation of a polysiloxaneboronic acid pinacol ester compound according to claim 1 comprising:
The polysiloxane and double bond boric acid pinacol ester are subjected to hydrosilation reaction under the catalysis of a catalyst, and the polysiloxane boric acid pinacol ester compound is prepared.
6. The method according to claim 5, wherein, the polyalkoxysilahydride is 1,3, 5-heptamethyl trisiloxane or 1,3, 5-heptamethyltrisiloxane; the double bond pinacol borate is vinyl boric acid pinacol ester or propenyl boric acid ortho-di-tertiary alcohol ester.
7. An electrolyte comprising any one or more of a lithium salt of an electrolyte, a solvent, and a pinacol ester compound of a polysiloxaneboronic acid as defined in any one of claims 1 to 4.
8. The electrolyte of claim 6, wherein the electrolyte lithium salt is selected from any one or more of lithium hexafluorophosphate, lithium perchlorate, lithium dioxalate borate, lithium difluorooxalate borate, lithium bistrifluoromethylsulfonimide, lithium bisfluorosulfonylimide, and their corresponding metal sodium salts; the solvent is selected from any one or more of carbonic acid ester solvents.
9. A lithium ion battery comprising the electrolyte of any one of claims 7-8.
10. An electrical device comprising the lithium ion battery of claim 9.
CN202410271784.5A 2024-03-11 2024-03-11 Polysiloxane boric acid pinacol ester compound, preparation method thereof, electrolyte, lithium ion battery and power utilization device Pending CN118146250A (en)

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