WO2021259084A1 - Binder having high ionic conductivity, and lithium ion battery containing same - Google Patents

Binder having high ionic conductivity, and lithium ion battery containing same Download PDF

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WO2021259084A1
WO2021259084A1 PCT/CN2021/099786 CN2021099786W WO2021259084A1 WO 2021259084 A1 WO2021259084 A1 WO 2021259084A1 CN 2021099786 W CN2021099786 W CN 2021099786W WO 2021259084 A1 WO2021259084 A1 WO 2021259084A1
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binder
lithium
pole piece
butadiene
hsch
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PCT/CN2021/099786
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French (fr)
Chinese (zh)
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储霖
李素丽
陈伟平
李俊义
徐延铭
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珠海冠宇电池股份有限公司
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Publication of WO2021259084A1 publication Critical patent/WO2021259084A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • 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

Definitions

  • the invention relates to a binder for a lithium ion battery and a lithium ion battery containing the binder, belonging to the technical field of lithium ion batteries, in particular to the field of binders for lithium ion batteries.
  • the binder in lithium ion battery not only plays the role of bonding between the active material layers, but also can be used for the bonding between the active material layer and the pole piece substrate. It plays an important role and is one of the important components of the battery.
  • PVDF polyvinylidene fluoride
  • SBR butadiene copolymer
  • the present invention provides a binder with high ion conductivity and lithium containing the binder.
  • the use of ion conductive polymers as binders in the present invention can significantly improve the transmission efficiency of lithium ion batteries, thereby improving the cycle performance of lithium ion batteries, and also help to improve the formation of SEI film, avoiding the occurrence of lithium ion battery cycles.
  • the phenomenon of declining capacity is greatly improved.
  • the ionic conductivity of the binder is greatly improved compared with the SBR binder, and the normal temperature cycle, rate performance, and low temperature performance of the lithium ion battery using the binder are also significantly improved.
  • a binder includes at least one styrene-butadiene modified polymer, the modified polymer includes a side chain whose end group is -COOLi or -SO 3 Li, and the side chain The chain is connected to the main chain through a sulfur atom at the other end.
  • the side chain is connected to the carbon atom on the butadiene polymerization unit on the main chain through the sulfur atom at the other end, and the carbon atom is the carbon-carbon double bond in the butadiene polymerization unit before modification. Of one carbon.
  • the structural formula of the side chain is *-SR 1 -R 2 , * represents the connection end to the main chain;
  • R 1 is a substituted or unsubstituted alkylene group, and the substituent may be selected from an aryl group;
  • R 2 It is -COOLi or -SO 3 Li.
  • the unmodified styrene-butadiene polymer is a styrene-butadiene random copolymer (SBR) and a styrene-butadiene block copolymer (SBS).
  • SBR styrene-butadiene random copolymer
  • SBS styrene-butadiene block copolymer
  • the modified polymer has a structure represented by the following formula (1) or formula (2):
  • R 1 is a substituted or unsubstituted C 1-36 alkylene group, and the substituent may be selected from an aryl group;
  • R 2 is -COOLi or -SO 3 Li;
  • m is an integer between 1 and 10,000, n is an integer between 1 and 10000.
  • the binder further includes water-soluble lithium cellulose, and the added amount of the water-soluble lithium cellulose is 0-80% of the mass of the modified polymer.
  • the peel strength of the adhesive is 50 N/m or more; and/or the ionic conductivity of the adhesive is 4 ⁇ 10 -4 -5 ⁇ 10 -4 S ⁇ cm -1 .
  • the present invention provides a pole piece, which includes the above-mentioned adhesive.
  • the pole piece is prepared by coating a slurry on one or both sides of the current collector, and the slurry includes 0.5-5 wt% of the above-mentioned binder.
  • the present invention provides a lithium ion battery, which includes the above-mentioned pole piece.
  • the present invention provides a binder with high ionic conductivity and a lithium ion battery containing the binder.
  • the binder of the present invention includes at least one polymer, and the polymer includes a terminal group of -COOLi or -SO. 3 Li side chain, the -COOLi or -SO 3 Li contained in the side chain of the polymer can dissociate lithium ions, so that the binder becomes a conductive polymer under the action of an electric field.
  • the introduction of carboxyl or sulfonic acid anions can enhance the bonding strength of the binder and increase the cycle life of the lithium ion battery.
  • Fig. 1 is a schematic diagram of the structure of the adhesive peel strength test device of the present invention.
  • Fig. 2 is a graph showing the EIS test results of the electrochemical impedance of Examples 1-7 and Comparative Example 1 of the present invention.
  • the present invention provides a binder, the binder includes at least one styrene-butadiene modified polymer, and the modified polymer includes a terminal group of -COOLi or -SO 3
  • the side chain of Li is connected to the main chain through a sulfur atom at the other end.
  • the side chain is connected to the carbon atom on the butadiene polymerization unit on the main chain through the sulfur atom at the other end, and the carbon atom is the carbon in the butadiene polymerization unit before modification.
  • the structural formula of the side chain is *-SR 1 -R 2 , * represents the connection end to the main chain;
  • R 1 is a substituted or unsubstituted alkylene group, and the substituent may be selected from aryl groups. ⁇ ;
  • R 2 is -COOLi or -SO 3 Li.
  • the alkylene group may be a linear alkylene group substituted or unsubstituted with an aryl group, a branched alkylene group substituted or unsubstituted with an aryl group, and a cycloalkylene group substituted or unsubstituted with an aryl group.
  • the aryl group is phenyl
  • the carbon atoms of the alkylene group may be 1-36, and preferably 1-20, such as 1-12, such as 1-6, such as 1, 2, 3, 4, 5, or 6.
  • the side chain is introduced through the click reaction of a mercapto group and an alkenyl group.
  • the unmodified styrene-butadiene polymer is a substance known to those skilled in the art.
  • it may be a random copolymer of styrene-butadiene (SBR) or styrene-butadiene block copolymer (SBS), specifically, for example, styrene-butadiene rubber, or styrene-butadiene rubber emulsion (SBR emulsion), the The SBR emulsion is commercially available products, such as Zeon BM400B, BM480.
  • the modified polymer has a structure represented by the following formula (1) or formula (2):
  • R 1 is a C 1-36 alkylene group
  • R 2 is -COOLi or -SO 3 Li
  • m is an integer between 1 and 10,000
  • n is an integer between 1 and 10,000.
  • the m is an integer between 1 and 5000, and n is an integer between 1 and 2000.
  • the modified polymer having the structure represented by formula (1) or formula (2) is a block copolymer or a random copolymer.
  • the R 1 is a C 1-20 alkylene group.
  • the R 1 is -CH 2 -, -CH 2 CH 2 -, -CH 2 CH(CH 3 )-, -CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2- , -CH 2 CH(CH 2 CH 3 )-, -CH 2 CH 2 CH(CH 3 )-, -CH 2 C(CH 3 ) 2 -, -CH 2 CH(CH 3 )CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH(CH 2 CH 3 )-, -CH 2 CH 2 CH(CH 2 CH 3 )-, -CH 2 CH 2 CH(CH 2 CH 3 )-, -CH 2 CH 2 CH(CH 2 CH 3 )-, -CH 2 (CH 2 ) 4 CH 2 -, -CH 2 (CH 2 ) 5 CH 2 -, -CH 2 (CH 2 ) 6 CH 2 -, -CH 2
  • the number of carbon atoms is too large and the carbon chain is too long (the number of carbon atoms is greater than 36, such as greater than 20), water soluble The performance is not good, and the reactivity of the sulfhydryl group is reduced.
  • the binder further includes water-soluble lithium cellulose.
  • the water-soluble lithium cellulose is selected from at least one of carboxymethyl cellulose lithium, carboxyethyl cellulose lithium, hydroxymethyl cellulose lithium, hydroxyethyl cellulose lithium or hydroxypropyl cellulose lithium One, preferably lithium carboxymethyl cellulose.
  • the added amount of the water-soluble lithium cellulose is 0-80% of the mass of the modified polymer, such as 0%, 1%, 5%, 10%, 15%, 20% , 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%.
  • the peel strength of the adhesive is 50 N/m or more, for example, 50-80 N/m.
  • the ionic conductivity of the binder is 4 ⁇ 10 -4 -5 ⁇ 10 -4 S ⁇ cm -1 .
  • the binder is an emulsion binder.
  • the solid content of the emulsion binder is 30-60% by weight, preferably 40-50% by weight.
  • the viscosity of the emulsion binder is 10-1000 mPa ⁇ s, preferably 300-500 mPa ⁇ s.
  • the pH of the emulsion binder is 6-8.
  • the present invention also provides a method for preparing the above-mentioned adhesive, and the method includes the following steps:
  • the styrene-butadiene polymer is mixed with mercapto carboxylic acid or mercapto sulfonic acid, click reaction occurs, and the modified polymer is prepared by further acid-base neutralization reaction; or,
  • the mercaptocarboxylic acid or sulfonic acid is neutralized by acid and base to obtain the mercaptocarboxylate lithium salt or mercaptosulfonate lithium salt, and then the styrene-butadiene polymer is mixed with mercaptocarboxylate lithium salt or mercaptosulfonate lithium salt , A click reaction occurs, and the modified polymer is prepared.
  • the method includes the following steps:
  • n and m are as described above.
  • the method includes the following steps:
  • n and m are as described above.
  • step (1) after the polymer represented by formula (3) is mixed with mercaptocarboxylic acid or mercaptosulfonic acid, a click reaction can occur, and the mercaptocarboxylic acid or mercaptosulfonic acid The mercapto group in is added to the unsaturated double bond in the polymer represented by formula (3).
  • the mercapto carboxylic acid is a C 1-36 mercapto carboxylic acid, for example, the mercapto carboxylic acid is a C 1-20 mercapto carboxylic acid,
  • the mercapto carboxylic acid is HSCH 2 COOH, HSCH 2 CH 2 COOH, HSCH 2 CH(CH 3 )COOH, HSCH 2 CH 2 CH 2 COOH, HSCH 2 CH 2 CH 2 CH 2 COOH, HSCH 2 CH(CH 2 CH 3 )COOH, HSCH 2 CH 2 CH(CH 3 )COOH, HSCH 2 C(CH 3 ) 2 COOH, HSCH 2 CH(CH 3 )CH 2 COOH, HSCH 2 CH 2 CH 2 CH 2 CH 2 COOH, HSCH 2 CH(CH 2 CH 2 CH 3 )COOH, HSCH 2 CH 2 CH(CH 2 CH 3 )COOH, HSCH 2 CH 2 CH(CH 2 CH 3 )COOH, HSCH 2 CH 2 CH(CH 2 CH 3 )COOH, HSCH 2 (CH 2 ) 4 CH
  • the mercapto sulfonic acid is C 1-36 mercapto acid
  • mercapto sulfonic acid is, for example, a C 1-20 mercapto sulfonic acid
  • the mercaptosulfonic acid is HSCH 2 SO 3 H, HSCH 2 CH 2 SO 3 H, HSCH 2 CH(CH 3 )SO 3 H, HSCH 2 CH 2 CH 2 SO 3 H, HSCH 2 CH 2 CH 2 CH 2 SO 3 H, HSCH 2 CH(CH 2 CH 3 )SO 3 H, HSCH 2 CH(CH 2 CH 3 )SO 3 H, HSCH 2 C(CH 3 ) 2 SO 3 H, HSCH 2 CH( CH 3 )CH 2 SO 3 H, HSCH 2 CH 2 CH 2 CH 2 SO 3 H, HSCH 2 CH(CH 2 CH 2 CH 3 )SO 3 H, HSCH 2 CH(CH 2 CH 2 CH 3 )SO 3 H, HSCH 2 CH 2 CH(CH 2 CH 3 )SO 3 H, HSCH 2 CH 2 CH(CH 2 CH 3 )
  • step (1) specifically includes the following steps:
  • reaction time is 5-48h, preferably 6-24h.
  • the temperature of the reaction is 20-100°C, preferably 30-50°C.
  • the stirring speed is 300-1000 rpm, preferably 500-800 rpm.
  • the inert gas is high-purity nitrogen or argon.
  • the photoinitiator is a free radical photoinitiator or an ionic photoinitiator.
  • the free radical photoinitiator is selected from benzoin ethers, xanthones, sulfide-containing benzophenones, anthraquinone, benzophenone and its derivatives, thioxanthone and dialkoxy At least one of acetophenone;
  • the ionic photoinitiator is selected from the group consisting of diaryl iodide, ferrocene salt, triaryl sulfide, diaryliodonium copper salt, phenacyl methyl pyridine At least one of oxalates.
  • the added amount of the mercapto carboxylic acid or the mercapto sulfonic acid is 0.2-10 wt% of the polymer mass represented by formula (3), preferably 1-5 wt%, for example, 1 wt%, 2 wt%, 3 wt% %, 4wt%, 5wt%.
  • the added amount of the photoinitiator is 0.05-0.5 wt% of the mass of the mercapto carboxylic acid or the mercapto sulfonic acid, for example, 0.05 wt%, 0.07 wt%, 0.09 wt%, 0.1 wt%, 0.15 wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, 0.5wt%.
  • the alkaline reagent is selected from lithium carbonate or lithium hydroxide, wherein the molar amount of lithium carbonate is the mercaptocarboxylic acid or the The molar amount of the mercaptosulfonic acid is 1/2-6/11, and the molar amount of the lithium hydroxide is equal to the molar amount of the mercaptocarboxylic acid or the mercaptosulfonic acid.
  • step (2) specifically includes the following steps: dispersing the product of step (1) in water, adding alkaline reagents under stirring conditions, and performing acid-base neutralization reaction.
  • the temperature of the acid-base neutralization reaction is 10-50°C, preferably 20-30°C.
  • the stirring speed is 300-1000 rpm, preferably 500-800 rpm.
  • the alkaline reagent can be added directly or in the form of an aqueous solution of the alkaline reagent, and the concentration of the aqueous solution of the alkaline reagent is 1-10% by weight, preferably 3-5% by weight.
  • step (a) specifically includes the following steps: dissolving mercaptocarboxylic acid or mercaptosulfonic acid in water, adding alkaline reagents under stirring conditions, and performing acid-base neutralization reaction.
  • the temperature of the acid-base neutralization reaction is 10-50°C, preferably 20-30°C.
  • the stirring speed is 300-1000 rpm, preferably 500-800 rpm.
  • the alkaline reagent can be added directly or in the form of an aqueous solution of the alkaline reagent, and the concentration of the aqueous solution of the alkaline reagent is 1-10% by weight, preferably 3-5% by weight.
  • step (b) after the polymer represented by formula (3) is mixed with the lithium salt of mercaptocarboxylic acid or the lithium salt of mercaptosulfonic acid, a click reaction can occur, and the mercapto group The mercapto group in the lithium salt of carboxylic acid or the lithium salt of mercaptosulfonic acid is added to the unsaturated double bond in the polymer represented by formula (3).
  • step (b) specifically includes the following steps:
  • reaction time is 5-48h, preferably 6-24h.
  • the temperature of the reaction is 20-100°C, preferably 30-50°C.
  • the stirring speed is 300-1000 rpm, preferably 500-800 rpm.
  • the inert gas is high-purity nitrogen or argon.
  • the photoinitiator is a free radical photoinitiator or an ionic photoinitiator.
  • the free radical photoinitiator is selected from benzoin ethers, xanthones, sulfide-containing benzophenones, anthraquinone, benzophenone and its derivatives, thioxanthone and dialkoxy At least one of acetophenone;
  • the ionic photoinitiator is selected from the group consisting of diaryl iodide, ferrocene salt, triaryl sulfide, diaryliodonium copper salt, phenacyl methyl pyridine At least one of oxalates.
  • the added amount of the lithium salt of mercaptocarboxylic acid or the lithium salt of mercaptosulfonic acid is 0.2-10wt% of the polymer mass represented by formula (3), preferably 1-5wt%, for example, 1wt %, 2wt%, 3wt%, 4wt%, 5wt%.
  • the added amount of the photoinitiator is 0.05-0.5wt% of the mass of the lithium salt of mercaptocarboxylic acid or the lithium salt of mercaptosulfonic acid, for example, 0.05wt%, 0.07wt%, 0.09wt% , 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, 0.5wt%.
  • the present invention provides a pole piece, which includes the above-mentioned adhesive.
  • the pole piece is prepared by coating a slurry on one or both sides of the current collector, and the slurry includes an active substance, an additive, and the above-mentioned binder.
  • the slurry includes 0.5-5% by weight of the above-mentioned binder, preferably 0.8-2.5% by weight of the above-mentioned binder, and preferably 1.5-2.5% by weight of the above-mentioned binder.
  • the pole piece is, for example, a positive pole piece or a negative pole piece.
  • the current collector is single-gloss aluminum foil, double-gloss aluminum foil or porous aluminum foil
  • the active material in the slurry is lithium iron phosphate, ternary cathode material, cobalt acid
  • the additive is a conductive agent
  • the conductive agent is at least one of graphite, carbon black, acetylene black, graphene, and carbon nanotubes.
  • the current collector is single-gloss copper foil, double-gloss copper foil or porous copper foil
  • the active material in the slurry is artificial graphite, natural graphite, and mesophase.
  • the additives are conductive agents and dispersants
  • the conductive agents are graphite, carbon black, acetylene black, and graphite
  • At least one of alkene and carbon nanotubes, and the dispersant is sodium carboxymethyl cellulose or lithium carboxymethyl cellulose.
  • the method for preparing the positive pole piece includes the following steps:
  • the method for preparing the negative pole piece includes the following steps:
  • the present invention proposes a lithium ion battery, which includes the above-mentioned pole piece.
  • the positive pole piece, the negative pole piece and the separator are assembled into electric cores by winding or lamination commonly used in the industry, and then encapsulated by aluminum plastic film, and then sequentially baked and injected into electrolysis.
  • Lithium-ion battery is obtained through the steps of liquid, chemical conversion and two sealing.
  • the capacity retention rate after 500 cycles of the 0.5C charge and discharge system at a normal temperature of 25° C. is 93% or more.
  • the lithium ion battery with the above pole piece can further reduce the internal resistance of the battery, so that the lithium ion battery has better rate performance, low temperature performance, and long cycle performance.
  • the high ion conductivity binder of the present invention is used to make lithium ion battery pole pieces according to the pole piece production process commonly used in the industry.
  • the lithium ion battery includes a positive pole piece, a negative pole piece, a separator and an electrolyte, which are assembled into an aluminum-plastic film flexible packaging battery.
  • the peel strength involved in the following examples is measured by the following method:
  • the viscosity involved in the following examples is measured by a common digital display rotary viscometer.
  • the electrochemical impedance EIS involved in the following examples is measured by the following method:
  • the above-mentioned adhesive was tested, and the conductivity was 4.4 ⁇ 10 -4 S ⁇ cm -1 .
  • the negative active material silicon-based/graphite composite negative electrode material SiOx/C, gram capacity is 400mAh/g
  • the high ionic conductivity binder prepared above sodium carboxymethyl cellulose and conductive carbon black
  • a uniformly dispersed negative electrode slurry is obtained, which contains 96.5wt% of silicon-based/graphite composite negative electrode material, 1.5wt% of the above-prepared high ionic conductivity binder, and 1wt% of carboxymethyl fiber Sodium, 1wt% conductive carbon black
  • the solid content of the negative electrode slurry is 45wt%
  • the viscosity is 3500-5500mPa ⁇ s.
  • the negative electrode slurry is passed through a 150-mesh gauze, it is evenly coated on both sides of the copper foil, dried at 80-130°C for 4 hours, and compacted by a roller press with a compaction density of 1.5-1.7g/cm 3 to obtain Negative pole piece.
  • the solid content contains 96.5wt% lithium cobaltate and 1.5wt% PVDF and 2wt% conductive carbon black, the solid content of the positive electrode slurry is 68wt%, and the viscosity is 21505 mPa ⁇ s.
  • the positive electrode slurry is evenly coated on both sides of the aluminum foil, dried at 100-130° C. for 4 hours, and compacted by a roller press with a compaction density of 2.8-3.5 g/cm 3 to obtain positive pole pieces.
  • the positive electrode sheet, the negative electrode sheet and the separator (PP/PE/PP composite film, thickness 9 ⁇ m, porosity 41%) are wound into a battery core, then baked, injected with electrolyte, formed, and sealed to obtain a lithium ion battery.
  • the above-mentioned adhesive was tested and the conductivity was 4.3 ⁇ 10 -4 S ⁇ cm -1 .
  • the above-mentioned adhesive was tested, and the conductivity was 4.2 ⁇ 10 -4 S ⁇ cm -1 .
  • the above-mentioned adhesive was tested, and the conductivity was 4.6 ⁇ 10 -4 S ⁇ cm -1 .
  • the above-mentioned adhesive was tested, and the conductivity was 4.8 ⁇ 10 -4 S ⁇ cm -1 .
  • the above-mentioned adhesive was tested, and the conductivity was 4.7 ⁇ 10 -4 S ⁇ cm -1 .
  • the above-mentioned adhesive was tested, and the conductivity was 4.9 ⁇ 10 -4 S ⁇ cm -1 .
  • Example 2 Other operations are the same as in Example 1, except that the sodium carboxymethyl cellulose is replaced with the same amount of lithium carboxymethyl cellulose during the preparation of the negative electrode slurry, and the other conditions are the same.
  • Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the negative electrode compounding process uses commercial non-modified SBR (Zeon's BM-480, the conductivity is 2.1 ⁇ 10 -4 S ⁇ cm -1 ), and other conditions are the same .
  • test items include rate performance (rate discharge), low temperature performance (0°C charge, -20°C discharge), and cycle retention.
  • rate performance rate discharge
  • low temperature performance (0°C charge, -20°C discharge)
  • cycle retention 0°C charge, -20°C discharge
  • Rate performance Discharge the fully charged battery at 0.2C/0.5C/1.0C/1.5C/2.0C to the cut-off voltage, and calculate the capacity retention rate (capacity retention rate compared to 0.2C discharge), which is 0.5C /0.2C, 1.0C/0.2C, 1.5C/0.2C, 2C/0.2C.
  • Low temperature performance 0°C charging: put the battery in a 0°C oven, charge at 0.1C, discharge at 0.2C, charge and discharge 10 times, dissecting and observe the surface state of the negative pole piece after fully charged off.
  • Discharge at -20°C Place the fully charged battery in a low temperature box at -20°C and discharge at 0.2C to calculate the discharge capacity.
  • Cycle retention rate 500 cycles of charge and discharge at 0.5C at room temperature 25°C, calculate the capacity retention rate after 500 cycles.
  • the modified SBR of the present invention introduces carboxyl or sulfonic acid groups through click chemistry, and then neutralizes them with acid and alkali to turn them into lithium carboxylate or lithium sulfonate, which brings extreme The peel strength of the sheet is improved.
  • the lithium carboxylate salt or the lithium sulfonate salt can dissociate free lithium ions, which facilitates the transmission of lithium ions.
  • the use of modified SBR can reduce the electrochemical impedance. Therefore, compared with the unmodified SBR, the battery using the binder of the present invention has better rate performance, low temperature performance and cycle life.
  • FIG. 2 is a graph of the EIS test results of the electrochemical impedance of Examples 1-8 and Comparative Example 1 of the present invention. It can be seen from Figure 2 that when Z" is 0, the abscissa corresponds to the ohmic impedance, the diameter of the first semicircular arc corresponds to the SEI film impedance Rsei, and the second semicircular arc corresponds to Rsei.
  • the abscissa value of is the charge transfer impedance Rct, but usually Rsei and Rct have no obvious boundary and will overlap to form a large semi-circular arc. So in general, the diameter and the two semi-circular arcs are collectively referred to as electrochemical impedance.

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Abstract

The present invention provides a binder having high ionic conductivity, and a lithium ion battery containing same. The binder of the present invention contains at least one polymer, the polymer comprises a side chain having an end group of -COOLi or -SO3Li, and Li ions can be dissociated from the -COOLi or-SO3Li contained in the side chain of the polymer, so that the binder becomes a conductive polymer under the action of an electric field. The ionic conductivity of the lithium ion battery is greatly improved, the transmission speed of Li ions can be increased, and a certain transmission capability can still be provided even at a low temperature. Compared with existing unmodified SBR, the binder has higher ionic conductivity, rate performance, and low temperature performance. On the other hand, due to the introduction of carboxyl or sulfonate negative ions, the bonding strength of the binder can be enhanced, and the cycle life of the lithium ion battery is prolonged.

Description

一种高离子电导率的粘结剂及含有该粘结剂的锂离子电池Binder with high ion conductivity and lithium ion battery containing the binder 技术领域Technical field
本发明涉及一种锂离子电池用粘结剂及含有该粘结剂的锂离子电池，属于锂离子电池技术领域，具体属于锂离子电池用粘结剂领域。The invention relates to a binder for a lithium ion battery and a lithium ion battery containing the binder, belonging to the technical field of lithium ion batteries, in particular to the field of binders for lithium ion batteries.
背景技术Background technique
锂离子电池中的粘结剂作为一种聚合物，既起到活性材料层间的粘结作用，又可以用于活性材料层与极片基材之间的粘结，在电池的制造和性能方面起重要作用，是电池的重要组分之一。As a kind of polymer, the binder in lithium ion battery not only plays the role of bonding between the active material layers, but also can be used for the bonding between the active material layer and the pole piece substrate. It plays an important role and is one of the important components of the battery.
目前使用最多的粘结剂是聚偏氟乙烯(PVDF)，苯乙烯与丁二烯的共聚物(SBR)。其中PVDF多采用油性有机试剂(N-甲基吡咯烷酮)作为溶剂，但这会带来环境污染的问题；水系的SBR类的乳液型粘结剂在环保方面显现出更大优势，但由其组成的电极体系却存在锂离子传输能力受限等问题，仍需改进。The most commonly used binders are polyvinylidene fluoride (PVDF), styrene and butadiene copolymer (SBR). Among them, PVDF mostly uses oily organic reagents (N-methylpyrrolidone) as solvents, but this will cause environmental pollution problems; water-based SBR emulsion binders show greater advantages in environmental protection, but they are composed of them However, there are problems with the limited lithium ion transmission capacity of the electrode system, which still needs to be improved.
发明内容Summary of the invention
为了改善现有技术的不足，特别是现有技术中SBR类粘结剂的锂离子传输能力弱的问题，本发明提供了一种高离子电导率的粘结剂及含有该粘结剂的锂离子电池，本发明使用离子导电聚合物作为粘结剂可以显著提高锂离子电池的传输效率，从而提高锂离子电池的循环性能，也有助于改善SEI膜的形成，避免随着锂离子电池循环出现容量不断下降的现象。同时所述粘结剂的离子电导率相较于SBR类粘结剂有大幅提高，且使用所述粘结剂的锂离子电池的常温循环、倍率性能、低温性能也得到较明显的改进。In order to improve the shortcomings of the prior art, especially the weak lithium ion transport capability of the SBR binder in the prior art, the present invention provides a binder with high ion conductivity and lithium containing the binder. For ion batteries, the use of ion conductive polymers as binders in the present invention can significantly improve the transmission efficiency of lithium ion batteries, thereby improving the cycle performance of lithium ion batteries, and also help to improve the formation of SEI film, avoiding the occurrence of lithium ion battery cycles. The phenomenon of declining capacity. At the same time, the ionic conductivity of the binder is greatly improved compared with the SBR binder, and the normal temperature cycle, rate performance, and low temperature performance of the lithium ion battery using the binder are also significantly improved.
本发明目的是通过如下技术方案实现的：The purpose of the present invention is achieved through the following technical solutions:
一种粘结剂，所述粘结剂包括至少一种苯乙烯-丁二烯改性聚合物，所述 改性聚合物包括端基为-COOLi或-SO 3Li的侧链，所述侧链通过另一端的硫原子与主链相连。 A binder, the binder includes at least one styrene-butadiene modified polymer, the modified polymer includes a side chain whose end group is -COOLi or -SO 3 Li, and the side chain The chain is connected to the main chain through a sulfur atom at the other end.
根据本发明，所述侧链通过另一端的硫原子与主链上的丁二烯聚合单元上的碳原子相连，所述碳原子为改性前丁二烯聚合单元中的碳碳双键中的一个碳。According to the present invention, the side chain is connected to the carbon atom on the butadiene polymerization unit on the main chain through the sulfur atom at the other end, and the carbon atom is the carbon-carbon double bond in the butadiene polymerization unit before modification. Of one carbon.
根据本发明，所述侧链的结构式为*-S-R 1-R 2，*表示与主链的连接端；R 1为取代或未取代的亚烷基，取代基可以选自芳基；R 2为-COOLi或-SO 3Li。 According to the present invention, the structural formula of the side chain is *-SR 1 -R 2 , * represents the connection end to the main chain; R 1 is a substituted or unsubstituted alkylene group, and the substituent may be selected from an aryl group; R 2 It is -COOLi or -SO 3 Li.
根据本发明，未改性的苯乙烯-丁二烯类聚合物是苯乙烯-丁二烯的无规共聚物(SBR)，苯乙烯-丁二烯的嵌段共聚物(SBS)。According to the present invention, the unmodified styrene-butadiene polymer is a styrene-butadiene random copolymer (SBR) and a styrene-butadiene block copolymer (SBS).
根据本发明，所述改性聚合物具有如下式(1)或式(2)所示的结构：According to the present invention, the modified polymer has a structure represented by the following formula (1) or formula (2):
Figure PCTCN2021099786-appb-000001
Figure PCTCN2021099786-appb-000001
其中，所述R 1为取代或未取代的C 1-36的亚烷基，取代基可以选自芳基；R 2为-COOLi或-SO 3Li；m为1-10000之间的整数，n为1-10000之间的整数。 Wherein, the R 1 is a substituted or unsubstituted C 1-36 alkylene group, and the substituent may be selected from an aryl group; R 2 is -COOLi or -SO 3 Li; m is an integer between 1 and 10,000, n is an integer between 1 and 10000.
根据本发明，所述的粘结剂还包括水溶性纤维素锂，所述水溶性纤维素锂的加入量为所述改性聚合物质量的0-80％。According to the present invention, the binder further includes water-soluble lithium cellulose, and the added amount of the water-soluble lithium cellulose is 0-80% of the mass of the modified polymer.
根据本发明，所述粘结剂的剥离强度为50N/m以上；和/或，所述粘结剂的离子电导率为4×10 -4-5×10 -4S·cm -1。 According to the present invention, the peel strength of the adhesive is 50 N/m or more; and/or the ionic conductivity of the adhesive is 4×10 -4 -5×10 -4 S·cm -1 .
本发明提供了一种极片，所述极片包括上述的粘结剂。The present invention provides a pole piece, which includes the above-mentioned adhesive.
根据本发明，所述极片是通过在集流体一侧或两侧表面涂覆浆料制备得到的，所述浆料包括0.5-5wt％的上述的粘结剂。According to the present invention, the pole piece is prepared by coating a slurry on one or both sides of the current collector, and the slurry includes 0.5-5 wt% of the above-mentioned binder.
本发明提供了一种锂离子电池，所述锂离子电池包括上述的极片。The present invention provides a lithium ion battery, which includes the above-mentioned pole piece.
本发明的有益效果：The beneficial effects of the present invention:
本发明提供了一种高离子电导率的粘结剂及含有该粘结剂的锂离子电池，本发明的粘结剂包括至少一种聚合物，该聚合物包括端基为-COOLi或-SO 3Li的侧链，所述聚合物的侧链中含有的-COOLi或-SO 3Li能够解离出锂离子，使所述粘结剂在电场作用下变成了可导电的聚合物，大幅度提高了锂离子电池的离子电导率，其可以加速Li离子的传输速度，甚至在低温下也能有一定的传输能力。相比于现有的未改性的SBR，其具有较高的离子电导率、倍率性能和低温性能。另一方面由于还引入了羧基或磺酸负离子，可以增强粘结剂的粘接强度，提高了锂离子电池的循环寿命。 The present invention provides a binder with high ionic conductivity and a lithium ion battery containing the binder. The binder of the present invention includes at least one polymer, and the polymer includes a terminal group of -COOLi or -SO. 3 Li side chain, the -COOLi or -SO 3 Li contained in the side chain of the polymer can dissociate lithium ions, so that the binder becomes a conductive polymer under the action of an electric field. This greatly increases the ion conductivity of the lithium-ion battery, which can accelerate the transmission speed of Li ions, and has a certain transmission capacity even at low temperatures. Compared with the existing unmodified SBR, it has higher ionic conductivity, rate performance and low temperature performance. On the other hand, the introduction of carboxyl or sulfonic acid anions can enhance the bonding strength of the binder and increase the cycle life of the lithium ion battery.
附图说明Description of the drawings
图1为本发明的粘结剂的剥离强度测试装置的结构示意图。Fig. 1 is a schematic diagram of the structure of the adhesive peel strength test device of the present invention.
图2为本发明的实施例1-7和对比例1的电化学阻抗EIS测试结果图。Fig. 2 is a graph showing the EIS test results of the electrochemical impedance of Examples 1-7 and Comparative Example 1 of the present invention.
具体实施方式detailed description
[高离子电导率的粘结剂][Binder with high ionic conductivity]
如前所述，本发明提供一种粘结剂，所述粘结剂包括至少一种苯乙烯-丁二烯改性聚合物，所述改性聚合物包括端基为-COOLi或-SO 3Li的侧链，所述侧链通过另一端的硫原子与主链相连。 As mentioned above, the present invention provides a binder, the binder includes at least one styrene-butadiene modified polymer, and the modified polymer includes a terminal group of -COOLi or -SO 3 The side chain of Li is connected to the main chain through a sulfur atom at the other end.
在一个具体的实施方式中，所述侧链通过另一端的硫原子与主链上的丁二烯聚合单元上的碳原子相连，所述碳原子为改性前丁二烯聚合单元中的碳碳双键中的一个碳。In a specific embodiment, the side chain is connected to the carbon atom on the butadiene polymerization unit on the main chain through the sulfur atom at the other end, and the carbon atom is the carbon in the butadiene polymerization unit before modification. One carbon in the carbon double bond.
在一个具体的实施方式中，所述侧链的结构式为*-S-R 1-R 2，*表示与主链的连接端；R 1为取代或未取代的亚烷基，取代基可以选自芳基；R 2为-COOLi 或-SO 3Li。 In a specific embodiment, the structural formula of the side chain is *-SR 1 -R 2 , * represents the connection end to the main chain; R 1 is a substituted or unsubstituted alkylene group, and the substituent may be selected from aryl groups.基; R 2 is -COOLi or -SO 3 Li.
示例性地，所述亚烷基可以是芳基取代或未取代的直链亚烷基、芳基取代或未取代的支链亚烷基、芳基取代或未取代的环亚烷基。Exemplarily, the alkylene group may be a linear alkylene group substituted or unsubstituted with an aryl group, a branched alkylene group substituted or unsubstituted with an aryl group, and a cycloalkylene group substituted or unsubstituted with an aryl group.
示例性地，所述芳基为苯基。Illustratively, the aryl group is phenyl.
示例性地，所述亚烷基的碳原子可以为1-36，还优选为1-20，如1-12，如1-6，如1、2、3、4、5或6。Exemplarily, the carbon atoms of the alkylene group may be 1-36, and preferably 1-20, such as 1-12, such as 1-6, such as 1, 2, 3, 4, 5, or 6.
在一个具体的实施方式中，所述侧链是通过巯基与烯基的点击反应引入的。In a specific embodiment, the side chain is introduced through the click reaction of a mercapto group and an alkenyl group.
在一个具体的实施方式中，未改性的苯乙烯-丁二烯类聚合物是本领域技术人员已知的物质，示例性地，其可以是苯乙烯-丁二烯的无规共聚物(SBR)或苯乙烯-丁二烯的嵌段共聚物(SBS)，具体的，例如可以是苯乙烯-丁二烯橡胶，还例如为苯乙烯-丁二烯橡胶乳液(SBR乳液)，所述的SBR乳液为市售易得的产品，如瑞翁BM400B、BM480。In a specific embodiment, the unmodified styrene-butadiene polymer is a substance known to those skilled in the art. Illustratively, it may be a random copolymer of styrene-butadiene ( SBR) or styrene-butadiene block copolymer (SBS), specifically, for example, styrene-butadiene rubber, or styrene-butadiene rubber emulsion (SBR emulsion), the The SBR emulsion is commercially available products, such as Zeon BM400B, BM480.
在一个具体的实施方式中，所述改性聚合物具有如下式(1)或式(2)所示的结构：In a specific embodiment, the modified polymer has a structure represented by the following formula (1) or formula (2):
Figure PCTCN2021099786-appb-000002
Figure PCTCN2021099786-appb-000002
其中，所述R 1为C 1-36的亚烷基，R 2为-COOLi或-SO 3Li；m为1-10000之间的整数，n为1-10000之间的整数。 Wherein, the R 1 is a C 1-36 alkylene group, R 2 is -COOLi or -SO 3 Li; m is an integer between 1 and 10,000, and n is an integer between 1 and 10,000.
在一个具体的实施方式中，所述m为1-5000之间的整数，n为1-2000之间的整数。In a specific embodiment, the m is an integer between 1 and 5000, and n is an integer between 1 and 2000.
在一个具体的实施方式中，具有式(1)或式(2)所示结构的改性聚合物为嵌段共聚物或为无规共聚物。In a specific embodiment, the modified polymer having the structure represented by formula (1) or formula (2) is a block copolymer or a random copolymer.
在一个具体的实施方式中，所述R 1为C 1-20亚烷基。示例性地，所述R 1为-CH 2-，-CH 2CH 2-，-CH 2CH(CH 3)-，-CH 2CH 2CH 2-，-CH 2CH 2CH 2CH 2-，-CH 2CH(CH 2CH 3)-，-CH 2CH 2CH(CH 3)-，-CH 2C(CH 3) 2-，-CH 2CH(CH 3)CH 2-，-CH 2CH 2CH 2CH 2CH 2-，-CH 2CH(CH 2CH 2CH 3)-，-CH 2CH 2CH(CH 2CH 3)-，-CH 2CH 2CH 2CH(CH 3)-，-CH 2(CH 2) 4CH 2-，-CH 2(CH 2) 5CH 2-，-CH 2(CH 2) 6CH 2-，-CH 2(CH 2) 7CH 2-，-CH 2(CH 2) 8CH 2-，-CH 2(CH 2) 9CH 2-，-CH 2(CH 2) 10CH 2-，-CH 2(CH 2) 11CH 2-，-CH 2(CH 2) 12CH 2-，-CH 2(CH 2) 13CH 2-，-CH 2(CH 2) 14CH 2-，-CH 2(CH 2) 15CH 2-，-CH 2(CH 2) 16CH 2-，-CH 2(CH 2) 17CH 2-，-CH 2(CH 2) 18CH 2-，1,4-亚环己基，1,3-亚环戊基。其中，所述R 1的碳原子数越多，能够赋予改性聚合物更好的机械性能，但碳原子数过多，碳链过长(碳原子数目大于36，如大于20)时，水溶性不好，巯基的反应活性降低。 In a specific embodiment, the R 1 is a C 1-20 alkylene group. Exemplarily, the R 1 is -CH 2 -, -CH 2 CH 2 -, -CH 2 CH(CH 3 )-, -CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2- , -CH 2 CH(CH 2 CH 3 )-, -CH 2 CH 2 CH(CH 3 )-, -CH 2 C(CH 3 ) 2 -, -CH 2 CH(CH 3 )CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH(CH 2 CH 2 CH 3 )-, -CH 2 CH 2 CH(CH 2 CH 3 )-, -CH 2 CH 2 CH 2 CH(CH 3 )-,-CH 2 (CH 2 ) 4 CH 2 -, -CH 2 (CH 2 ) 5 CH 2 -, -CH 2 (CH 2 ) 6 CH 2 -, -CH 2 (CH 2 ) 7 CH 2- , -CH 2 (CH 2 ) 8 CH 2 -, -CH 2 (CH 2 ) 9 CH 2 -, -CH 2 (CH 2 ) 10 CH 2 -, -CH 2 (CH 2 ) 11 CH 2 -,- CH 2 (CH 2 ) 12 CH 2 -, -CH 2 (CH 2 ) 13 CH 2 -, -CH 2 (CH 2 ) 14 CH 2 -, -CH 2 (CH 2 ) 15 CH 2 -, -CH 2 (CH 2 ) 16 CH 2 -, -CH 2 (CH 2 ) 17 CH 2 -, -CH 2 (CH 2 ) 18 CH 2 -, 1,4-cyclohexylene, 1,3-cyclopentylene. Wherein, the more carbon atoms of R 1 are, the better mechanical properties can be imparted to the modified polymer. However, when the number of carbon atoms is too large and the carbon chain is too long (the number of carbon atoms is greater than 36, such as greater than 20), water soluble The performance is not good, and the reactivity of the sulfhydryl group is reduced.
在一个具体的实施方式中，所述的粘结剂还包括水溶性纤维素锂。In a specific embodiment, the binder further includes water-soluble lithium cellulose.
具体的，所述水溶性纤维素锂选自羧甲基纤维素锂、羧乙基纤维素锂、羟甲基纤维素锂、羟乙基纤维素锂或羟丙基纤维素锂中的至少一种，优选为羧甲基纤维素锂。Specifically, the water-soluble lithium cellulose is selected from at least one of carboxymethyl cellulose lithium, carboxyethyl cellulose lithium, hydroxymethyl cellulose lithium, hydroxyethyl cellulose lithium or hydroxypropyl cellulose lithium One, preferably lithium carboxymethyl cellulose.
研究发现，水溶性纤维素锂中的羟基之间以及羟基与本发明的改性聚合物中的羧基或磺酸基之间能形成氢键作用，有助于高效三维网状结构的生成，同时由于水溶性纤维素锂中也可以解离出Li离子，从而能够进一步提升粘结剂的电导率。因此，水溶性纤维素锂的加入能够进一步提高该粘结剂的导电性和粘附性，优化其电化学性能。Studies have found that hydrogen bonds can be formed between the hydroxyl groups in the water-soluble lithium cellulose and between the hydroxyl groups and the carboxyl or sulfonic acid groups in the modified polymer of the present invention, which helps to form a high-efficiency three-dimensional network structure. Since Li ions can also be dissociated from the water-soluble lithium cellulose, the conductivity of the binder can be further improved. Therefore, the addition of water-soluble lithium cellulose can further improve the conductivity and adhesion of the binder, and optimize its electrochemical performance.
在一个具体的实施方式中，所述水溶性纤维素锂的加入量为所述改性聚合物质量的0-80％，如0％、1％、5％、10％、15％、20％、25％、30％、35％、40％、45％、50％、55％、60％、65％、70％、75％、80％。In a specific embodiment, the added amount of the water-soluble lithium cellulose is 0-80% of the mass of the modified polymer, such as 0%, 1%, 5%, 10%, 15%, 20% , 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%.
在一个具体的实施方式中，所述粘结剂的剥离强度为50N/m以上，例如 为50-80N/m。In a specific embodiment, the peel strength of the adhesive is 50 N/m or more, for example, 50-80 N/m.
在一个具体的实施方式中，所述粘结剂的离子电导率为4×10 -4-5×10 -4S·cm -1。 In a specific embodiment, the ionic conductivity of the binder is 4×10 -4 -5×10 -4 S·cm -1 .
在一个具体的实施方式中，所述粘结剂为乳液型粘结剂。In a specific embodiment, the binder is an emulsion binder.
在一个具体的实施方式中，所述乳液型粘结剂的固含量为30-60wt％，优选为40-50wt％。In a specific embodiment, the solid content of the emulsion binder is 30-60% by weight, preferably 40-50% by weight.
在一个具体的实施方式中，所述乳液型粘结剂的粘度为10-1000mPa·s，优选为300-500mPa·s。In a specific embodiment, the viscosity of the emulsion binder is 10-1000 mPa·s, preferably 300-500 mPa·s.
在一个具体的实施方式中，所述乳液型粘结剂的pH值为6-8。In a specific embodiment, the pH of the emulsion binder is 6-8.
[高离子电导率的粘结剂的制备方法][Preparation method of binder with high ionic conductivity]
如前所述，本发明还提供上述粘结剂的制备方法，所述方法包括如下步骤：As mentioned above, the present invention also provides a method for preparing the above-mentioned adhesive, and the method includes the following steps:
将苯乙烯-丁二烯类聚合物与巯基羧酸或巯基磺酸混合，发生点击反应，进一步通过酸碱中和反应，制备得到所述改性聚合物；或者，The styrene-butadiene polymer is mixed with mercapto carboxylic acid or mercapto sulfonic acid, click reaction occurs, and the modified polymer is prepared by further acid-base neutralization reaction; or,
将巯基羧酸或磺酸通过酸碱中和反应得到巯基羧酸锂盐或巯基磺酸锂盐，再将苯乙烯-丁二烯类聚合物与巯基羧酸锂盐或巯基磺酸锂盐混合，发生点击反应，制备得到所述改性聚合物。The mercaptocarboxylic acid or sulfonic acid is neutralized by acid and base to obtain the mercaptocarboxylate lithium salt or mercaptosulfonate lithium salt, and then the styrene-butadiene polymer is mixed with mercaptocarboxylate lithium salt or mercaptosulfonate lithium salt , A click reaction occurs, and the modified polymer is prepared.
在一个具体的实施方式中，所述方法包括如下步骤：In a specific embodiment, the method includes the following steps:
(1)将式(3)所示的聚合物与巯基羧酸或巯基磺酸混合，发生点击反应；(1) Mixing the polymer represented by formula (3) with mercapto carboxylic acid or mercapto sulfonic acid to cause a click reaction;
(2)加入碱性试剂，进行酸碱中和反应，制备得到所述改性聚合物；(2) Add alkaline reagents, carry out acid-base neutralization reaction, and prepare the modified polymer;
Figure PCTCN2021099786-appb-000003
Figure PCTCN2021099786-appb-000003
其中，n和m的定义如上所述。Among them, the definitions of n and m are as described above.
在一个具体的实施方式中，所述方法包括如下步骤：In a specific embodiment, the method includes the following steps:
(a)将巯基羧酸或巯基磺酸与碱性试剂混合，进行酸碱中和反应；(a) Mixing mercapto carboxylic acid or mercapto sulfonic acid with alkaline reagents to carry out acid-base neutralization reaction;
(b)加入式(3)所示的聚合物，进行点击反应，制备得到所述改性聚合物；(b) Adding the polymer represented by formula (3) and performing a click reaction to prepare the modified polymer;
Figure PCTCN2021099786-appb-000004
Figure PCTCN2021099786-appb-000004
其中，n和m的定义如上所述。Among them, the definitions of n and m are as described above.
在一个具体的实施方式中，步骤(1)中，所述式(3)所示的聚合物在与巯基羧酸或巯基磺酸混合后，可以发生点击反应，将巯基羧酸或巯基磺酸中的巯基加成到式(3)所示的聚合物中的不饱和双键上。In a specific embodiment, in step (1), after the polymer represented by formula (3) is mixed with mercaptocarboxylic acid or mercaptosulfonic acid, a click reaction can occur, and the mercaptocarboxylic acid or mercaptosulfonic acid The mercapto group in is added to the unsaturated double bond in the polymer represented by formula (3).
在一个具体的实施方式中，步骤(1)和步骤(a)中，所述的巯基羧酸为C 1-36的巯基羧酸，例如的巯基羧酸为C 1-20的巯基羧酸，示例性地，所述的巯基羧酸为HSCH 2COOH，HSCH 2CH 2COOH，HSCH 2CH(CH 3)COOH，HSCH 2CH 2CH 2COOH，HSCH 2CH 2CH 2CH 2COOH，HSCH 2CH(CH 2CH 3)COOH， HSCH 2CH 2CH(CH 3)COOH，HSCH 2C(CH 3) 2COOH，HSCH 2CH(CH 3)CH 2COOH，HSCH 2CH 2CH 2CH 2CH 2COOH，HSCH 2CH(CH 2CH 2CH 3)COOH，HSCH 2CH 2CH(CH 2CH 3)COOH，HSCH 2CH 2CH 2CH(CH 3)COOH，HSCH 2(CH 2) 4CH 2COOH，HSCH 2(CH 2) 5CH 2COOH，HSCH 2(CH 2) 6CH 2COOH，HSCH 2(CH 2) 7CH 2COOH，HSCH 2(CH 2) 8CH 2COOH，HSCH 2(CH 2) 9CH 2COOH，HSCH 2(CH 2) 10CH 2COOH，HSCH 2(CH 2) 11CH 2COOH，HSCH 2(CH 2) 12CH 2COOH，HSCH 2(CH 2) 13CH 2COOH，HSCH 2(CH 2) 14CH 2COOH，HSCH 2(CH 2) 15CH 2COOH，HSCH 2(CH 2) 16CH 2COOH，HSCH 2(CH 2) 17CH 2COOH，HSCH 2(CH 2) 18CH 2COOH，4-巯基环己基甲酸，3-巯基环戊基甲酸。 In a specific embodiment, in step (1) and step (a), the mercapto carboxylic acid is a C 1-36 mercapto carboxylic acid, for example, the mercapto carboxylic acid is a C 1-20 mercapto carboxylic acid, Exemplarily, the mercapto carboxylic acid is HSCH 2 COOH, HSCH 2 CH 2 COOH, HSCH 2 CH(CH 3 )COOH, HSCH 2 CH 2 CH 2 COOH, HSCH 2 CH 2 CH 2 CH 2 COOH, HSCH 2 CH(CH 2 CH 3 )COOH, HSCH 2 CH 2 CH(CH 3 )COOH, HSCH 2 C(CH 3 ) 2 COOH, HSCH 2 CH(CH 3 )CH 2 COOH, HSCH 2 CH 2 CH 2 CH 2 CH 2 COOH, HSCH 2 CH(CH 2 CH 2 CH 3 )COOH, HSCH 2 CH 2 CH(CH 2 CH 3 )COOH, HSCH 2 CH 2 CH 2 CH(CH 3 )COOH, HSCH 2 (CH 2 ) 4 CH 2 COOH, HSCH 2 (CH 2 ) 5 CH 2 COOH, HSCH 2 (CH 2 ) 6 CH 2 COOH, HSCH 2 (CH 2 ) 7 CH 2 COOH, HSCH 2 (CH 2 ) 8 CH 2 COOH, HSCH 2 ( CH 2 ) 9 CH 2 COOH, HSCH 2 (CH 2 ) 10 CH 2 COOH, HSCH 2 (CH 2 ) 11 CH 2 COOH, HSCH 2 (CH 2 ) 12 CH 2 COOH, HSCH 2 (CH 2 ) 13 CH 2 COOH, HSCH 2 (CH 2 ) 14 CH 2 COOH, HSCH 2 (CH 2 ) 15 CH 2 COOH, HSCH 2 (CH 2 ) 16 CH 2 COOH, HSCH 2 (CH 2 ) 17 CH 2 COOH, HSCH 2 (CH 2 ) 18 CH 2 COOH, 4-mercaptocyclohexyl carboxylic acid, 3-mercaptocyclopentyl carboxylic acid.
在一个具体的实施方式中，步骤(1)和步骤(a)中，所述的巯基磺酸为C 1-36的巯基磺酸，例如的巯基磺酸为C 1-20的巯基磺酸，示例性地，所述的巯基磺酸为HSCH 2SO 3H，HSCH 2CH 2SO 3H，HSCH 2CH(CH 3)SO 3H，HSCH 2CH 2CH 2SO 3H，HSCH 2CH 2CH 2CH 2SO 3H，HSCH 2CH(CH 2CH 3)SO 3H，HSCH 2CH 2CH(CH 3)SO 3H，HSCH 2C(CH 3) 2SO 3H，HSCH 2CH(CH 3)CH 2SO 3H，HSCH 2CH 2CH 2CH 2CH 2SO 3H，HSCH 2CH(CH 2CH 2CH 3)SO 3H，HSCH 2CH 2CH(CH 2CH 3)SO 3H，HSCH 2CH 2CH 2CH(CH 3)SO 3H，HSCH 2(CH 2) 4CH 2SO 3H，HSCH 2(CH 2) 5CH 2SO 3H，HSCH 2(CH 2) 6CH 2SO 3H，HSCH 2(CH 2) 7CH 2SO 3H，HSCH 2(CH 2) 8CH 2SO 3H，HSCH 2(CH 2) 9CH 2SO 3H，HSCH 2(CH 2) 10CH 2SO 3H，HSCH 2(CH 2) 11CH 2SO 3H，HSCH 2(CH 2) 12CH 2SO 3H，HSCH 2(CH 2) 13CH 2SO 3H，HSCH 2(CH 2) 14CH 2SO 3H，HSCH 2(CH 2) 15CH 2SO 3H，HSCH 2(CH 2) 16CH 2SO 3H，HSCH 2(CH 2) 17CH 2SO 3H，HSCH 2(CH 2) 18CH 2SO 3H，4-巯基环己基磺酸，3-巯基环戊基磺酸。 In a specific embodiment, step (1) and the step (a), the mercapto sulfonic acid is C 1-36 mercapto acid, mercapto sulfonic acid is, for example, a C 1-20 mercapto sulfonic acid, Exemplarily, the mercaptosulfonic acid is HSCH 2 SO 3 H, HSCH 2 CH 2 SO 3 H, HSCH 2 CH(CH 3 )SO 3 H, HSCH 2 CH 2 CH 2 SO 3 H, HSCH 2 CH 2 CH 2 CH 2 SO 3 H, HSCH 2 CH(CH 2 CH 3 )SO 3 H, HSCH 2 CH 2 CH(CH 3 )SO 3 H, HSCH 2 C(CH 3 ) 2 SO 3 H, HSCH 2 CH( CH 3 )CH 2 SO 3 H, HSCH 2 CH 2 CH 2 CH 2 CH 2 SO 3 H, HSCH 2 CH(CH 2 CH 2 CH 3 )SO 3 H, HSCH 2 CH 2 CH(CH 2 CH 3 )SO 3 H, HSCH 2 CH 2 CH 2 CH(CH 3 )SO 3 H, HSCH 2 (CH 2 ) 4 CH 2 SO 3 H, HSCH 2 (CH 2 ) 5 CH 2 SO 3 H, HSCH 2 (CH 2 ) 6 CH 2 SO 3 H, HSCH 2 (CH 2 ) 7 CH 2 SO 3 H, HSCH 2 (CH 2 ) 8 CH 2 SO 3 H, HSCH 2 (CH 2 ) 9 CH 2 SO 3 H, HSCH 2 (CH 2 ) 10 CH 2 SO 3 H, HSCH 2 (CH 2 ) 11 CH 2 SO 3 H, HSCH 2 (CH 2 ) 12 CH 2 SO 3 H, HSCH 2 (CH 2 ) 13 CH 2 SO 3 H, HSCH 2 (CH 2 ) 14 CH 2 SO 3 H, HSCH 2 (CH 2 ) 15 CH 2 SO 3 H, HSCH 2 (CH 2 ) 16 CH 2 SO 3 H, HSCH 2 (CH 2 ) 17 CH 2 SO 3 H, HSCH 2 (CH 2 ) 18 CH 2 SO 3 H, 4-mercaptocyclohexylsulfonic acid, 3-mercaptocyclopentylsulfonic acid.
在一个具体的实施方式中，步骤(1)中，具体包括如下步骤：In a specific embodiment, step (1) specifically includes the following steps:
将商品化的SBR乳液装入反应瓶，加入巯基羧酸或巯基磺酸，加入光引发剂，在惰性气体保护下进行搅拌，紫外光光照下发生反应。Put the commercial SBR emulsion into the reaction flask, add mercapto carboxylic acid or mercapto sulfonic acid, add photoinitiator, stir under the protection of inert gas, and react under ultraviolet light.
其中，所述反应的时间为5-48h，优选为6-24h。Wherein, the reaction time is 5-48h, preferably 6-24h.
其中，所述反应的温度为20-100℃，优选为30-50℃。Wherein, the temperature of the reaction is 20-100°C, preferably 30-50°C.
其中，所述搅拌的速度为300-1000rpm，优选为500-800rpm。Wherein, the stirring speed is 300-1000 rpm, preferably 500-800 rpm.
其中，所述的惰性气体为高纯氮气或者氩气。Wherein, the inert gas is high-purity nitrogen or argon.
其中，所述的光引发剂为自由基光引发剂或离子型光引发剂。Wherein, the photoinitiator is a free radical photoinitiator or an ionic photoinitiator.
其中，所述的自由基光引发剂选自安息香醚类、占吨酮、含硫醚二苯甲酮类、蒽醌、二苯甲酮及其衍生物、硫杂蒽酮及二烷氧基苯乙酮中的至少一种；所述的离子型光引发剂选自二芳基碘化物、二茂铁盐、三芳基硫化物、二芳基碘鎓铜盐中、苯甲酰甲基吡啶草酸盐中的至少一种。Wherein, the free radical photoinitiator is selected from benzoin ethers, xanthones, sulfide-containing benzophenones, anthraquinone, benzophenone and its derivatives, thioxanthone and dialkoxy At least one of acetophenone; the ionic photoinitiator is selected from the group consisting of diaryl iodide, ferrocene salt, triaryl sulfide, diaryliodonium copper salt, phenacyl methyl pyridine At least one of oxalates.
其中，所述巯基羧酸或所述巯基磺酸的加入量为式(3)所示的聚合物质量的0.2-10wt％，优选为1-5wt％，示例地，1wt％，2wt％，3wt％，4wt％，5wt％。Wherein, the added amount of the mercapto carboxylic acid or the mercapto sulfonic acid is 0.2-10 wt% of the polymer mass represented by formula (3), preferably 1-5 wt%, for example, 1 wt%, 2 wt%, 3 wt% %, 4wt%, 5wt%.
其中，所述光引发剂的加入量为所述巯基羧酸或所述巯基磺酸质量的0.05-0.5wt％，示例地，0.05wt％，0.07wt％，0.09wt％，0.1wt％，0.15wt％，0.2wt％，0.25wt％，0.3wt％，0.35wt％，0.4wt％，0.45wt％，0.5wt％。Wherein, the added amount of the photoinitiator is 0.05-0.5 wt% of the mass of the mercapto carboxylic acid or the mercapto sulfonic acid, for example, 0.05 wt%, 0.07 wt%, 0.09 wt%, 0.1 wt%, 0.15 wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, 0.5wt%.
在一个具体的实施方式中，步骤(2)和步骤(a)中，所述碱性试剂选自碳酸锂或者氢氧化锂，其中，所述碳酸锂的摩尔量为所述巯基羧酸或所述巯基磺酸摩尔量的1/2-6/11，所述氢氧化锂的摩尔量与所述巯基羧酸或所述巯基磺酸的摩尔量相等。In a specific embodiment, in step (2) and step (a), the alkaline reagent is selected from lithium carbonate or lithium hydroxide, wherein the molar amount of lithium carbonate is the mercaptocarboxylic acid or the The molar amount of the mercaptosulfonic acid is 1/2-6/11, and the molar amount of the lithium hydroxide is equal to the molar amount of the mercaptocarboxylic acid or the mercaptosulfonic acid.
在一个具体的实施方式中，步骤(2)中，具体包括如下步骤：将步骤(1)的产物分散在水中，搅拌条件下加入碱性试剂，进行酸碱中和反应。In a specific embodiment, step (2) specifically includes the following steps: dispersing the product of step (1) in water, adding alkaline reagents under stirring conditions, and performing acid-base neutralization reaction.
其中，所述酸碱中和反应的温度为10-50℃，优选为20-30℃。Wherein, the temperature of the acid-base neutralization reaction is 10-50°C, preferably 20-30°C.
其中，所述搅拌的速度为300-1000rpm，优选为500-800rpm。Wherein, the stirring speed is 300-1000 rpm, preferably 500-800 rpm.
其中，所述碱性试剂可以是直接加入，也可以是通过碱性试剂的水溶液的形式加入，所述碱性试剂的水溶液的浓度为1-10wt％，优选为3-5wt％。Wherein, the alkaline reagent can be added directly or in the form of an aqueous solution of the alkaline reagent, and the concentration of the aqueous solution of the alkaline reagent is 1-10% by weight, preferably 3-5% by weight.
在一个具体的实施方式中，步骤(a)中，具体包括如下步骤：将巯基羧酸或巯基磺酸溶于水中，搅拌条件下加入碱性试剂，进行酸碱中和反应。In a specific embodiment, step (a) specifically includes the following steps: dissolving mercaptocarboxylic acid or mercaptosulfonic acid in water, adding alkaline reagents under stirring conditions, and performing acid-base neutralization reaction.
其中，所述酸碱中和反应的温度为10-50℃，优选为20-30℃。Wherein, the temperature of the acid-base neutralization reaction is 10-50°C, preferably 20-30°C.
其中，所述搅拌的速度为300-1000rpm，优选为500-800rpm。Wherein, the stirring speed is 300-1000 rpm, preferably 500-800 rpm.
其中，所述碱性试剂可以是直接加入，也可以是通过碱性试剂的水溶液的形式加入，所述碱性试剂的水溶液的浓度为1-10wt％，优选为3-5wt％。Wherein, the alkaline reagent can be added directly or in the form of an aqueous solution of the alkaline reagent, and the concentration of the aqueous solution of the alkaline reagent is 1-10% by weight, preferably 3-5% by weight.
在一个具体的实施方式中，步骤(b)中，所述式(3)所示的聚合物在与巯基羧酸的锂盐或巯基磺酸的锂盐混合后，可以发生点击反应，将巯基羧酸的锂盐或巯基磺酸的锂盐中的巯基加成到式(3)所示的聚合物中的不饱和双键上。In a specific embodiment, in step (b), after the polymer represented by formula (3) is mixed with the lithium salt of mercaptocarboxylic acid or the lithium salt of mercaptosulfonic acid, a click reaction can occur, and the mercapto group The mercapto group in the lithium salt of carboxylic acid or the lithium salt of mercaptosulfonic acid is added to the unsaturated double bond in the polymer represented by formula (3).
在一个具体的实施方式中，步骤(b)中，具体包括如下步骤：In a specific embodiment, step (b) specifically includes the following steps:
将商品化的SBR乳液装入反应瓶，加入巯基羧酸的锂盐或巯基磺酸的锂盐，加入光引发剂，在惰性气体保护下进行搅拌，紫外光光照下发生反应。Put the commercial SBR emulsion into the reaction flask, add the lithium salt of mercaptocarboxylic acid or the lithium salt of mercaptosulfonic acid, add a photoinitiator, stir under the protection of inert gas, and react under ultraviolet light.
其中，所述反应的时间为5-48h，优选为6-24h。Wherein, the reaction time is 5-48h, preferably 6-24h.
其中，所述反应的温度为20-100℃，优选为30-50℃。Wherein, the temperature of the reaction is 20-100°C, preferably 30-50°C.
其中，所述搅拌的速度为300-1000rpm，优选为500-800rpm。Wherein, the stirring speed is 300-1000 rpm, preferably 500-800 rpm.
其中，所述的惰性气体为高纯氮气或者氩气。Wherein, the inert gas is high-purity nitrogen or argon.
其中，所述的光引发剂为自由基光引发剂或离子型光引发剂。Wherein, the photoinitiator is a free radical photoinitiator or an ionic photoinitiator.
其中，所述的自由基光引发剂选自安息香醚类、占吨酮、含硫醚二苯甲酮类、蒽醌、二苯甲酮及其衍生物、硫杂蒽酮及二烷氧基苯乙酮中的至少一种；所述的离子型光引发剂选自二芳基碘化物、二茂铁盐、三芳基硫化物、二芳基碘鎓铜盐中、苯甲酰甲基吡啶草酸盐中的至少一种。Wherein, the free radical photoinitiator is selected from benzoin ethers, xanthones, sulfide-containing benzophenones, anthraquinone, benzophenone and its derivatives, thioxanthone and dialkoxy At least one of acetophenone; the ionic photoinitiator is selected from the group consisting of diaryl iodide, ferrocene salt, triaryl sulfide, diaryliodonium copper salt, phenacyl methyl pyridine At least one of oxalates.
其中，所述巯基羧酸的锂盐或所述巯基磺酸的锂盐的加入量为式(3)所示的聚合物质量的0.2-10wt％，优选为1-5wt％，示例地，1wt％，2wt％，3wt％，4wt％，5wt％。Wherein, the added amount of the lithium salt of mercaptocarboxylic acid or the lithium salt of mercaptosulfonic acid is 0.2-10wt% of the polymer mass represented by formula (3), preferably 1-5wt%, for example, 1wt %, 2wt%, 3wt%, 4wt%, 5wt%.
其中，所述光引发剂的加入量为所述巯基羧酸的锂盐或所述巯基磺酸的锂盐质量的0.05-0.5wt％，示例地，0.05wt％，0.07wt％，0.09wt％，0.1wt％，0.15wt％，0.2wt％，0.25wt％，0.3wt％，0.35wt％，0.4wt％，0.45wt％，0.5wt％。[极片及其制备]Wherein, the added amount of the photoinitiator is 0.05-0.5wt% of the mass of the lithium salt of mercaptocarboxylic acid or the lithium salt of mercaptosulfonic acid, for example, 0.05wt%, 0.07wt%, 0.09wt% , 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, 0.5wt%. [Pole piece and its preparation]
如前所述，本发明提供了一种极片，所述极片包括上述的粘结剂。As mentioned above, the present invention provides a pole piece, which includes the above-mentioned adhesive.
在一个具体的实施方式中，所述极片是通过在集流体一侧或两侧表面涂覆浆料制备得到的，所述浆料包括活性物质、添加剂和上述的粘结剂。In a specific embodiment, the pole piece is prepared by coating a slurry on one or both sides of the current collector, and the slurry includes an active substance, an additive, and the above-mentioned binder.
示例性地，所述浆料包括0.5-5wt％的上述的粘结剂，优选包括0.8-2.5wt％的上述的粘结剂，还优选包括1.5-2.5wt％的上述的粘结剂。Exemplarily, the slurry includes 0.5-5% by weight of the above-mentioned binder, preferably 0.8-2.5% by weight of the above-mentioned binder, and preferably 1.5-2.5% by weight of the above-mentioned binder.
在一个具体的实施方式中，所述极片例如是正极极片或是负极极片。In a specific embodiment, the pole piece is, for example, a positive pole piece or a negative pole piece.
在一个具体的实施方式中，正极极片中，所述的集流体为单光面铝箔、双光面铝箔或多孔铝箔，浆料中的活性物质为磷酸铁锂、三元正极材料、钴酸锂中的至少一种，添加剂为导电剂，导电剂为石墨、炭黑、乙炔黑、石墨烯、碳纳米管中的至少一种。In a specific embodiment, in the positive pole piece, the current collector is single-gloss aluminum foil, double-gloss aluminum foil or porous aluminum foil, and the active material in the slurry is lithium iron phosphate, ternary cathode material, cobalt acid At least one of lithium, the additive is a conductive agent, and the conductive agent is at least one of graphite, carbon black, acetylene black, graphene, and carbon nanotubes.
在一个具体的实施方式中，负极极片中，所述的集流体为单光面铜箔、双光面铜箔或多孔铜箔，浆料中的活性物质为人造石墨、天然石墨、中间相碳球、氧化硅、纳米硅粉、氧化亚硅、硅碳、掺硅石墨、钛酸锂中的至少一种，添加剂为导电剂和分散剂，导电剂为石墨、炭黑、乙炔黑、石墨烯、碳纳米管中的至少一种，分散剂为羧甲基纤维素钠或羧甲基纤维素锂。In a specific embodiment, in the negative electrode sheet, the current collector is single-gloss copper foil, double-gloss copper foil or porous copper foil, and the active material in the slurry is artificial graphite, natural graphite, and mesophase. At least one of carbon balls, silicon oxide, nano silicon powder, silicon oxide, silicon carbon, silicon-doped graphite, lithium titanate, the additives are conductive agents and dispersants, and the conductive agents are graphite, carbon black, acetylene black, and graphite At least one of alkene and carbon nanotubes, and the dispersant is sodium carboxymethyl cellulose or lithium carboxymethyl cellulose.
在一个具体的实施方式中，所述正极极片的制备方法包括如下步骤：In a specific embodiment, the method for preparing the positive pole piece includes the following steps:
(1)将正极活性物质(例如钴酸锂96.2wt％)、导电剂(例如炭黑2wt％)、上述的粘结剂(1.8wt％)混合均匀，得到正极浆料；(1) Mix the positive electrode active material (for example, lithium cobalt oxide 96.2% by weight), the conductive agent (for example, carbon black 2% by weight), and the above-mentioned binder (1.8% by weight) uniformly to obtain a positive electrode slurry;
(2)将正极浆料涂覆在集流体的表面，烘烤后即得到正极极片。(2) The positive electrode slurry is coated on the surface of the current collector, and the positive electrode piece is obtained after baking.
在一个具体的实施方式中，所述负极极片的制备方法包括如下步骤：In a specific embodiment, the method for preparing the negative pole piece includes the following steps:
(1)将负极活性物质(例如石墨96.5wt％)、导电剂(例如炭黑1wt％)、分散剂(羧甲基纤维素钠1wt％)、上述的粘结剂(1.5wt％)混合均匀，得到负极浆料；(1) Mix the negative electrode active material (for example, graphite 96.5wt%), conductive agent (for example, carbon black 1wt%), dispersant (sodium carboxymethyl cellulose 1wt%), and the above-mentioned binder (1.5wt%) evenly. , To obtain the negative electrode slurry;
(2)将负极浆料涂覆在集流体的表面，烘烤后即得到负极极片。(2) The negative electrode slurry is coated on the surface of the current collector, and the negative electrode piece is obtained after baking.
[锂离子电池][Lithium Ion Battery]
如上所述，本发明提出了一种锂离子电池，所述锂离子电池包括上述的 极片。As described above, the present invention proposes a lithium ion battery, which includes the above-mentioned pole piece.
在一个具体的实施方式中，将正极极片、负极极片和隔膜通过行业内通用的卷绕或者叠片式组装成电芯，再通过铝塑膜进行封装，再依次经过烘烤、注入电解液、化成、二封工序即得到锂离子电池。In a specific embodiment, the positive pole piece, the negative pole piece and the separator are assembled into electric cores by winding or lamination commonly used in the industry, and then encapsulated by aluminum plastic film, and then sequentially baked and injected into electrolysis. Lithium-ion battery is obtained through the steps of liquid, chemical conversion and two sealing.
在一个具体的实施方式中，常温25℃下，以0.5C充放电制度循环500次后的容量保持率为93％以上。In a specific embodiment, the capacity retention rate after 500 cycles of the 0.5C charge and discharge system at a normal temperature of 25° C. is 93% or more.
其中，加入上述极片的锂离子电池能够进一步降低电池的内阻，从而使得锂离子电池具有更好的倍率性能、低温性能、长循环性能。Among them, the lithium ion battery with the above pole piece can further reduce the internal resistance of the battery, so that the lithium ion battery has better rate performance, low temperature performance, and long cycle performance.
将本发明的高离子电导率的粘结剂按本行业通用的极片生产工艺制作锂离子电池极片。所述的锂离子电池包括正极极片、负极极片、隔膜和电解液，组装成铝塑膜软包装电池。The high ion conductivity binder of the present invention is used to make lithium ion battery pole pieces according to the pole piece production process commonly used in the industry. The lithium ion battery includes a positive pole piece, a negative pole piece, a separator and an electrolyte, which are assembled into an aluminum-plastic film flexible packaging battery.
下文将结合具体实施例对本发明做更进一步的详细说明。应当理解，下列实施例仅为示例性地说明和解释本发明，而不应被解释为对本发明保护范围的限制。凡基于本发明上述内容所实现的技术均涵盖在本发明旨在保护的范围内。Hereinafter, the present invention will be further described in detail with reference to specific embodiments. It should be understood that the following embodiments are only illustrative and explanation of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the foregoing contents of the present invention are covered by the scope of the present invention.
下述实施例中所使用的实验方法如无特殊说明，均为常规方法；下述实施例中所用的试剂、材料等，如无特殊说明，均可从商业途径得到。The experimental methods used in the following examples are conventional methods unless otherwise specified; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial sources.
下述实施例中涉及到的剥离强度是采用如下方法测试得到的：The peel strength involved in the following examples is measured by the following method:
将负极浆料涂覆于集流体(如铜箔)表面，经过干燥、冷压制成极片，将制备完成的极片裁剪为20×100mm尺寸的测试试样，备用；将极片用双面胶粘接需要测试的那一面，并用压辊压实，使之与极片完全贴合；试样的双面胶的另外一面粘贴于不锈钢表面，将试样一端反向弯曲，弯曲角度为180°；采用高铁拉力机测试，将不锈钢一端固定于拉力机下方夹具，试样弯曲末端固定于上方夹具，调整试样角度，保证上下端位于垂直位置，然后以50mm/min的速度拉伸试样，直到试样全部从基板剥离，记录过程中的位移和作用力， 认为受力平衡时的力为极片的剥离强度，装置示意图1所示。Coat the negative electrode slurry on the surface of the current collector (such as copper foil), dry and cold press to form pole pieces, and cut the prepared pole pieces into test specimens with a size of 20×100mm for use; use double-sided pole pieces Glue the side that needs to be tested, and compact it with a pressing roller to make it fit the pole piece completely; the other side of the double-sided tape of the sample is pasted on the stainless steel surface, and one end of the sample is reversely bent at a bending angle of 180 °; Use the high-speed rail tensile machine to test, fix one end of the stainless steel to the fixture below the tensile machine, and fix the bent end of the specimen to the upper fixture, adjust the angle of the specimen to ensure that the upper and lower ends are in the vertical position, and then stretch the specimen at a speed of 50mm/min , Until the sample is completely peeled off from the substrate, record the displacement and force during the process, and consider the force when the force is balanced to be the peel strength of the pole piece, as shown in Figure 1 of the device.
下述实施例中涉及到的粘度是利用常见的数显式旋转粘度计测量得到的。The viscosity involved in the following examples is measured by a common digital display rotary viscometer.
下述实施例中涉及到的电化学阻抗EIS是采用如下方法测试得到的：The electrochemical impedance EIS involved in the following examples is measured by the following method:
(1)制作单片软包半电池：将得到的负极极片，在85℃下烘干，冲成61*42mm的极片，另外将锂片充成63*45mm的极片，中间为16μm隔膜基膜，然后组装制成软包半电池，注液后常温静置24h，然后上夹板待测试；(1) Make a single-chip soft-pack half-cell: dry the obtained negative pole piece at 85°C and punch it into a 61*42mm pole piece. In addition, charge the lithium piece into a 63*45mm pole piece with a middle size of 16μm. Separator base film, then assembled into a soft-pack half-cell, after filling it, let it stand at room temperature for 24 hours, and then put it on the splint for testing;
(2)EIS测试：频率范围1-500KHz，振幅：5mV。(2) EIS test: frequency range 1-500KHz, amplitude: 5mV.
下述实施例中涉及到的电导率的是采用如下方法测试得到的：The electrical conductivity involved in the following examples is measured by the following method:
(1)制作扣式对称电池：将适量乳液型粘结剂涂覆于铜箔上，在85℃下烘干，剥离后测量粘结剂膜的厚度，然后将膜片制成对称电池，另一边为铜箔，中间不加隔膜，注液后常温静置24h，然后热压使界面充分接触(0.2MPa，60℃，1min)；(1) Making a button-type symmetric battery: Coat an appropriate amount of emulsion adhesive on copper foil, dry at 85°C, measure the thickness of the adhesive film after peeling, and then make the membrane into a symmetrical battery. One side is copper foil with no diaphragm in the middle. After liquid injection, let it stand at room temperature for 24 hours, and then hot press to make the interface fully contact (0.2MPa, 60℃, 1min);
(2)EIS测试：频率范围1-500KHz，振幅：5mV；(2) EIS test: frequency range 1-500KHz, amplitude: 5mV;
(3)粘结剂的离子电导率σ＝L/(RA)，A表示粘结剂膜的面积，L表示膜的厚度，其中R由EIS测出得到的欧姆阻抗。(3) The ionic conductivity of the adhesive σ=L/(RA), A represents the area of the adhesive film, L represents the thickness of the film, and R is the ohmic impedance measured by EIS.
实施例1Example 1
高离子电导率的粘结剂的制备：Preparation of high ionic conductivity binder:
(1)取500g商品化的瑞翁BM-480型号的SBR乳液(固含量为45wt％)置于反应烧瓶中，机械搅拌800rpm，升温至35℃，保温30min，通入氮气，加入5g的巯基乙酸、0.005g的2-羟基-2-甲基-1-苯基丙酮，紫外灯照射，反应24h，降温至25℃。(1) Take 500g of commercial Zeon BM-480 SBR emulsion (solid content of 45wt%) into the reaction flask, mechanically stir at 800rpm, heat up to 35°C, keep for 30min, blow in nitrogen, and add 5g of mercapto group Acetic acid, 0.005g of 2-hydroxy-2-methyl-1-phenylacetone, irradiated with ultraviolet lamp, reacted for 24h, and cooled to 25°C.
(2)将1.3g的氢氧化锂溶于水中，配制成浓度为5wt％的氢氧化锂水溶液，滴加到步骤(1)的反应体系中，调至pH为7，继续搅拌2h，得到高离子电导率的粘结剂，粘度为450mPa·s。(2) Dissolve 1.3 g of lithium hydroxide in water to prepare an aqueous solution of lithium hydroxide with a concentration of 5 wt%, add it dropwise to the reaction system of step (1), adjust to pH 7, and continue stirring for 2 hours to obtain high The binder with ionic conductivity has a viscosity of 450mPa·s.
对上述粘结剂进行测试，电导率为4.4×10 -4S·cm -1。 The above-mentioned adhesive was tested, and the conductivity was 4.4×10 -4 S·cm -1 .
负极极片的制备：Preparation of negative pole piece:
将负极活性物质硅基/石墨复合负极材料(SiOx/C，克容量为400mAh/g)、上述制备得到的高离子电导率的粘结剂、羧甲基纤维素钠和导电炭黑分散在去离子水中，搅拌后得到均匀分散的负极浆料，其中包含96.5wt％的硅基/石墨复合负极材料、1.5wt％的上述制备得到的高离子电导率的粘结剂、1wt％羧甲基纤维素钠、1wt％的导电炭黑，负极浆料的固体含量为45wt％，粘度为3500-5500mPa·s。将负极浆料过150目纱网后，均匀地涂覆在铜箔两面，经过80-130℃干燥4h，利用辊压机对其压实，压实密度为1.5-1.7g/cm 3，得到负极极片。 The negative active material silicon-based/graphite composite negative electrode material (SiOx/C, gram capacity is 400mAh/g), the high ionic conductivity binder prepared above, sodium carboxymethyl cellulose and conductive carbon black are dispersed in the After stirring in ionized water, a uniformly dispersed negative electrode slurry is obtained, which contains 96.5wt% of silicon-based/graphite composite negative electrode material, 1.5wt% of the above-prepared high ionic conductivity binder, and 1wt% of carboxymethyl fiber Sodium, 1wt% conductive carbon black, the solid content of the negative electrode slurry is 45wt%, and the viscosity is 3500-5500mPa·s. After the negative electrode slurry is passed through a 150-mesh gauze, it is evenly coated on both sides of the copper foil, dried at 80-130°C for 4 hours, and compacted by a roller press with a compaction density of 1.5-1.7g/cm 3 to obtain Negative pole piece.
正极极片的制备：Preparation of positive pole piece:
将正极活性物质钴酸锂、粘结剂PVDF和导电炭黑分散在N-甲基吡咯烷酮，搅拌后得到均匀分散的正极浆料，其中固体成分包含96.5wt％的钴酸锂、1.5wt％的PVDF和2wt％的导电炭黑，正极浆料的固体含量为68wt％，粘度为21505mPa·s。将正极浆料均匀地涂覆在铝箔两面，经过100-130℃干燥4h，利用辊压机对其压实，压实密度为2.8-3.5g/cm 3，得到正极极片。 Disperse the positive electrode active material lithium cobaltate, the binder PVDF and conductive carbon black in N-methylpyrrolidone, and stir to obtain a uniformly dispersed positive electrode slurry. The solid content contains 96.5wt% lithium cobaltate and 1.5wt% PVDF and 2wt% conductive carbon black, the solid content of the positive electrode slurry is 68wt%, and the viscosity is 21505 mPa·s. The positive electrode slurry is evenly coated on both sides of the aluminum foil, dried at 100-130° C. for 4 hours, and compacted by a roller press with a compaction density of 2.8-3.5 g/cm 3 to obtain positive pole pieces.
锂离子电池的制备：Preparation of Lithium Ion Battery:
将正极片、负极片和隔膜(PP/PE/PP复合膜，厚度9μm，孔隙率为41％)卷绕成电芯，然后烘烤、注入电解液、化成、二封后得到锂离子电池。The positive electrode sheet, the negative electrode sheet and the separator (PP/PE/PP composite film, thickness 9 μm, porosity 41%) are wound into a battery core, then baked, injected with electrolyte, formed, and sealed to obtain a lithium ion battery.
实施例2Example 2
其他操作同实施例1，区别仅在于：高离子电导率的粘结剂：Other operations are the same as in Example 1, the only difference is: the binder with high ionic conductivity:
(1)取500g商品化的瑞翁BM-480型号的SBR乳液(固含量为45wt％)置于反应烧瓶中，机械搅拌800rpm，升温至35℃，保温30min，通入氮气，加入10g的3-巯基丙酸、0.0125g的二芳基碘鎓盐，紫外灯照射，反应28h，降温至25℃。(1) Take 500g of commercial Zeon BM-480 SBR emulsion (with a solid content of 45wt%) in a reaction flask, mechanically stir at 800 rpm, raise the temperature to 35°C, keep for 30 minutes, and add 10 g of 3 -Mercaptopropionic acid, 0.0125g of diaryliodonium salt, irradiated with ultraviolet lamp, reacted for 28h, and cooled to 25°C.
(2)将2.26g的氢氧化锂溶于水中，配制成浓度为5wt％的氢氧化锂水溶液，滴加到步骤(1)的反应体系中，调至pH为7，继续搅拌2h，得到高离子电导率的粘结剂，粘度为480mPa·s。(2) Dissolve 2.26g of lithium hydroxide in water to prepare an aqueous solution of lithium hydroxide with a concentration of 5wt%, add it dropwise to the reaction system of step (1), adjust to pH 7, and continue to stir for 2h to obtain high The binder with ionic conductivity has a viscosity of 480mPa·s.
对上述粘结剂进行测试，电导率为4.3×10 -4S·cm -1。 The above-mentioned adhesive was tested and the conductivity was 4.3×10 -4 S·cm -1 .
实施例3Example 3
其他操作同实施例1，区别仅在于：高离子电导率的粘结剂：Other operations are the same as in Example 1, the only difference is: the binder with high ionic conductivity:
(1)取500g商品化的瑞翁BM-480型号的SBR乳液(固含量为45wt％)置于反应烧瓶中，机械搅拌800rpm，升温至35℃，保温30min，通入氮气，加入5g的4-巯基丁酸、0.003g的2-羟基-2-甲基-1-苯基丙酮，紫外灯照射，反应24h，降温至25℃。(1) Take 500g of commercial Zeon BM-480 SBR emulsion (with a solid content of 45wt%) in a reaction flask, mechanically stir at 800 rpm, raise the temperature to 35°C, keep for 30 minutes, blow in nitrogen, and add 5 g of 4 -Mercaptobutyric acid, 0.003g of 2-hydroxy-2-methyl-1-phenylacetone, irradiated with a UV lamp, reacted for 24h, and cooled to 25°C.
(2)将1g的氢氧化锂溶于水中，配制成浓度为5wt％的氢氧化锂水溶液，滴加到步骤(1)的反应体系中，调至pH为7，继续搅拌2h，得到高离子电导率的粘结剂，粘度为330mPa·s。(2) Dissolve 1g of lithium hydroxide in water to prepare an aqueous solution of lithium hydroxide with a concentration of 5wt%, add it dropwise to the reaction system of step (1), adjust to pH 7, and continue to stir for 2h to obtain high ions The conductivity of the binder has a viscosity of 330mPa·s.
对上述粘结剂进行测试，电导率为4.2×10 -4S·cm -1。 The above-mentioned adhesive was tested, and the conductivity was 4.2×10 -4 S·cm -1 .
实施例4Example 4
其他操作同实施例1，区别仅在于：高离子电导率的粘结剂：Other operations are the same as in Example 1, the only difference is: the binder with high ionic conductivity:
(1)取500g商品化的瑞翁BM-480型号的SBR乳液(固含量为45wt％)置于反应烧瓶中，机械搅拌800rpm，升温至35℃，保温30min，通入氮气，加入5g的6-巯基己酸、0.0025g的二芳基碘鎓盐，紫外灯照射，反应24h，降温至25℃。(1) Take 500g of commercial Zeon BM-480 SBR emulsion (solid content of 45wt%) and place it in the reaction flask, mechanically stir at 800rpm, raise the temperature to 35°C, keep for 30min, and add nitrogen gas, and add 5g of 6 -Mercaptohexanoic acid, 0.0025g of diaryliodonium salt, irradiated with ultraviolet lamp, reacted for 24h, and cooled to 25°C.
(2)将0.8g的氢氧化锂溶于水中，配制成浓度为5wt％的氢氧化锂水溶液，滴加到步骤(1)的反应体系中，调至pH为7，继续搅拌2h，得到高离子电导率的粘结剂，粘度为445mPa·s。(2) Dissolve 0.8 g of lithium hydroxide in water to prepare an aqueous solution of lithium hydroxide with a concentration of 5 wt%, add it dropwise to the reaction system of step (1), adjust to pH 7, and continue to stir for 2 hours to obtain high The binder with ionic conductivity has a viscosity of 445 mPa·s.
对上述粘结剂进行测试，电导率为4.6×10 -4S·cm -1。 The above-mentioned adhesive was tested, and the conductivity was 4.6×10 -4 S·cm -1 .
实施例5Example 5
其他操作同实施例1，区别仅在于：高离子电导率的粘结剂：Other operations are the same as in Example 1, the only difference is: the binder with high ionic conductivity:
(1)取500g商品化的瑞翁BM-480型号的SBR乳液(固含量为45wt％)置于反应烧瓶中，机械搅拌800rpm，升温至35℃，保温30min，通入氮气，加入5g的2-巯基乙磺酸、0.002g的2-羟基-2-甲基-1-苯基丙酮，紫外灯照射，反应24h，降温至25℃。(1) Take 500g of commercial Zeon BM-480 SBR emulsion (with a solid content of 45wt%) in a reaction flask, mechanically stir at 800 rpm, raise the temperature to 35°C, keep for 30 minutes, and add nitrogen gas, and add 5 g of 2 -Mercaptoethanesulfonic acid, 0.002g of 2-hydroxy-2-methyl-1-phenylacetone, irradiated with ultraviolet light, reacted for 24h, and cooled to 25°C.
(2)将0.84g的氢氧化锂溶于水中，配制成浓度为5wt％的氢氧化锂水溶液，滴加到步骤(1)的反应体系中，调至pH为7，继续搅拌2h，得到高离子电导率的粘结剂，粘度为480mPa·s。(2) Dissolve 0.84 g of lithium hydroxide in water to prepare an aqueous solution of lithium hydroxide with a concentration of 5 wt%, add it dropwise to the reaction system of step (1), adjust to pH 7, and continue stirring for 2 hours to obtain high The binder with ionic conductivity has a viscosity of 480mPa·s.
对上述粘结剂进行测试，电导率为4.8×10 -4S·cm -1。 The above-mentioned adhesive was tested, and the conductivity was 4.8×10 -4 S·cm -1 .
实施例6Example 6
其他操作同实施例1，区别仅在于：高离子电导率的粘结剂：Other operations are the same as in Example 1, the only difference is: the binder with high ionic conductivity:
(1)取500g商品化的瑞翁BM-480型号的SBR乳液(固含量为45wt％)置于反应烧瓶中，机械搅拌800rpm，升温至35℃，保温30min，通入氮气，加入10.5g的3-巯基-1-丙磺酸、0.004g的苯甲酰甲基吡啶草酸盐，紫外灯照射，反应25h，降温至25℃。(1) Take 500g of commercial Zeon BM-480 SBR emulsion (with a solid content of 45wt%) in a reaction flask, mechanically stir at 800 rpm, raise the temperature to 35°C, keep it for 30 minutes, and add 10.5g of nitrogen. 3-mercapto-1-propanesulfonic acid, 0.004g of phenacylpyridine oxalate, irradiated with ultraviolet light, reacted for 25h, and cooled to 25°C.
(2)将1.41g的碳酸锂溶于水中，配制成浓度为1wt％的氢氧化锂水溶液，滴加到步骤(1)的反应体系中，调至pH为7，继续搅拌3h，得到高离子电导率的粘结剂，粘度为490mPa·s。(2) Dissolve 1.41 g of lithium carbonate in water to prepare a lithium hydroxide aqueous solution with a concentration of 1% by weight, add it dropwise to the reaction system of step (1), adjust to pH 7, and continue to stir for 3 hours to obtain high ions The conductivity of the binder has a viscosity of 490mPa·s.
对上述粘结剂进行测试，电导率为4.7×10 -4S·cm -1。 The above-mentioned adhesive was tested, and the conductivity was 4.7×10 -4 S·cm -1 .
实施例7Example 7
其他操作同实施例1，区别仅在于：高离子电导率的粘结剂：Other operations are the same as in Example 1, the only difference is: the binder with high ionic conductivity:
(1)取500g商品化的瑞翁BM-480型号的SBR乳液(固含量为45wt％)置 于反应烧瓶中，机械搅拌800rpm，升温至35℃，保温30min，通入氮气，加入12g的4-巯基-1-丁磺酸、0.003g的二芳基碘鎓盐，紫外灯照射，反应25h，降温至25℃。(1) Take 500g of commercial Zeon BM-480 SBR emulsion (with a solid content of 45wt%) in a reaction flask, mechanically stir at 800 rpm, raise the temperature to 35°C, keep for 30 minutes, blow in nitrogen, and add 12g of 4 -Mercapto-1-butanesulfonic acid, 0.003g of diaryliodonium salt, irradiated with a UV lamp, reacted for 25h, and cooled to 25°C.
(2)将1.69g的碳酸锂溶于水中，配制成浓度为1wt％的氢氧化锂水溶液，滴加到步骤(1)的反应体系中，调至pH为7，继续搅拌3h，得到高离子电导率的粘结剂，粘度为448mPa·s。(2) Dissolve 1.69 g of lithium carbonate in water to prepare a lithium hydroxide aqueous solution with a concentration of 1% by weight, add it dropwise to the reaction system of step (1), adjust to pH 7, and continue to stir for 3 hours to obtain high ions The conductivity of the binder has a viscosity of 448mPa·s.
对上述粘结剂进行测试，电导率为4.9×10 -4S·cm -1。 The above-mentioned adhesive was tested, and the conductivity was 4.9×10 -4 S·cm -1 .
实施例8Example 8
其他操作同实施例1，区别仅在于，负极浆料配制过程中将羧甲基纤维素钠替换为等量的羧甲基纤维素锂，其他条件一样。Other operations are the same as in Example 1, except that the sodium carboxymethyl cellulose is replaced with the same amount of lithium carboxymethyl cellulose during the preparation of the negative electrode slurry, and the other conditions are the same.
对上述粘结剂进行测试，电导率为4.85×10 -4S·cm -1。 The above-mentioned adhesive was tested, and the conductivity was 4.85×10 -4 S·cm -1 .
对比例1Comparative example 1
对比例1与实施例1不同之处在于，负极配料过程使用的是商用非改性的SBR(瑞翁的BM-480，电导率为2.1×10 -4S·cm -1)，其他条件一样。 The difference between Comparative Example 1 and Example 1 is that the negative electrode compounding process uses commercial non-modified SBR (Zeon's BM-480, the conductivity is 2.1×10 -4 S·cm -1 ), and other conditions are the same .
测试例1Test case 1
对实施例和对比例制备得到的电池进行性能测试，测试项目包括倍率性能(倍率放电)、低温性能(0℃充电、-20℃放电)和循环保持率，测试过程如下：Perform performance tests on the batteries prepared in the Examples and Comparative Examples. The test items include rate performance (rate discharge), low temperature performance (0°C charge, -20°C discharge), and cycle retention. The test process is as follows:
倍率性能(倍率放电)：将满电电池分别在0.2C/0.5C/1.0C/1.5C/2.0C放电至截止电压，计算容量保持率(比0.2C放电的容量保持率)，即0.5C/0.2C，1.0C/0.2C，1.5C/0.2C，2C/0.2C的值。Rate performance (rate discharge): Discharge the fully charged battery at 0.2C/0.5C/1.0C/1.5C/2.0C to the cut-off voltage, and calculate the capacity retention rate (capacity retention rate compared to 0.2C discharge), which is 0.5C /0.2C, 1.0C/0.2C, 1.5C/0.2C, 2C/0.2C.
低温性能：0℃充电：将电池静置在0℃烘箱中，以0.1C充电、0.2C放电，充放电10次，满电下台后解剖观察负极极片表面状态。-20℃放电：将满电电 池静置在-20℃的低温箱中，以0.2C放电，计算放电容量。Low temperature performance: 0℃ charging: put the battery in a 0℃ oven, charge at 0.1C, discharge at 0.2C, charge and discharge 10 times, dissecting and observe the surface state of the negative pole piece after fully charged off. Discharge at -20°C: Place the fully charged battery in a low temperature box at -20°C and discharge at 0.2C to calculate the discharge capacity.
循环保持率：常温25℃下，以0.5C充放电循环500次，计算500次后的容量保持率。Cycle retention rate: 500 cycles of charge and discharge at 0.5C at room temperature 25°C, calculate the capacity retention rate after 500 cycles.
以上测试结果如下表1至表2所示：The above test results are shown in Table 1 to Table 2:
表1实施例1-8和对比例1制备得到的电池的倍率性能Table 1 Rate performance of the batteries prepared in Examples 1-8 and Comparative Example 1
Figure PCTCN2021099786-appb-000005
Figure PCTCN2021099786-appb-000005
表2实施例1-8和对比例1制备得到的电池的低温性能及循环保持率Table 2 Low-temperature performance and cycle retention rate of the batteries prepared in Examples 1-8 and Comparative Example 1
Figure PCTCN2021099786-appb-000006
Figure PCTCN2021099786-appb-000006
表3实施例1-8和对比例1制备得到的极片的剥离强度Table 3 Peel strength of pole pieces prepared in Examples 1-8 and Comparative Example 1
Figure PCTCN2021099786-appb-000007
Figure PCTCN2021099786-appb-000007
从上述数据可以看出，采用本发明的改性SBR通过点击化学反应引入羧基或磺酸基，再通过酸碱中和使其变为羧酸锂盐或磺酸锂盐，这样带来了极片剥离强度的提升，另外羧酸锂盐或磺酸锂盐能解离出自由锂离子，有助于锂离子的传输，从图2可以看出，使用改性SBR能够降低电化学阻抗。所以相 对于未改性的SBR，采用本发明的粘结剂的电池，有更好的倍率性能、低温性能及循环寿命。It can be seen from the above data that the modified SBR of the present invention introduces carboxyl or sulfonic acid groups through click chemistry, and then neutralizes them with acid and alkali to turn them into lithium carboxylate or lithium sulfonate, which brings extreme The peel strength of the sheet is improved. In addition, the lithium carboxylate salt or the lithium sulfonate salt can dissociate free lithium ions, which facilitates the transmission of lithium ions. It can be seen from Figure 2 that the use of modified SBR can reduce the electrochemical impedance. Therefore, compared with the unmodified SBR, the battery using the binder of the present invention has better rate performance, low temperature performance and cycle life.
图2为本发明的实施例1-8和对比例1的电化学阻抗EIS测试结果图。从图2中可以看出，当Z”为0时，横坐标对应的值为欧姆阻抗，第一个半圆弧的直径对应的横坐标值为SEI膜阻抗Rsei，第二个半圆弧对应的横坐标值为电荷转移阻抗Rct，但是通常Rsei与Rct无明显界限，会重合形成一个大的半圆弧。所以总的来说将两个半圆弧的的直径和统称为电化学阻抗。可以明显看出改性的SBR组装的单片软包半电池(实施例1-8)的电化学阻抗(1.5-1.75Ω)比未改性的SBR组装的单片软包半电池(对比例1)的电化学阻抗(2Ω)小，另外实施例8对比实施例1可以发现在搭配羧甲基纤维素锂使用时，电化学阻抗能进一步降低。FIG. 2 is a graph of the EIS test results of the electrochemical impedance of Examples 1-8 and Comparative Example 1 of the present invention. It can be seen from Figure 2 that when Z" is 0, the abscissa corresponds to the ohmic impedance, the diameter of the first semicircular arc corresponds to the SEI film impedance Rsei, and the second semicircular arc corresponds to Rsei. The abscissa value of is the charge transfer impedance Rct, but usually Rsei and Rct have no obvious boundary and will overlap to form a large semi-circular arc. So in general, the diameter and the two semi-circular arcs are collectively referred to as electrochemical impedance. It can be clearly seen that the electrochemical impedance (1.5-1.75Ω) of the monolithic soft-pack half-cell assembled by the modified SBR (Examples 1-8) is higher than that of the monolithic soft-pack half-cell assembled by the unmodified SBR (comparative example). The electrochemical impedance (2Ω) of 1) is small. In addition, the comparison of Example 8 and Example 1 shows that when used with lithium carboxymethyl cellulose, the electrochemical impedance can be further reduced.
以上，对本发明的实施方式进行了说明。但是，本发明不限定于上述实施方式。凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。In the foregoing, the embodiments of the present invention have been described. However, the present invention is not limited to the above-mentioned embodiment. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

  1. 一种粘结剂，其中，所述粘结剂包括至少一种苯乙烯-丁二烯改性聚合物，所述改性聚合物包括端基为-COOLi或-SO 3Li的侧链，所述侧链通过另一端的硫原子与主链相连。 A binder, wherein the binder includes at least one styrene-butadiene modified polymer, and the modified polymer includes a side chain whose end group is -COOLi or -SO 3 Li, and The side chain is connected to the main chain through a sulfur atom at the other end.
  2. 根据权利要求1所述的粘结剂，其中，所述侧链通过另一端的硫原子与主链上的丁二烯聚合单元上的碳原子相连，所述碳原子为改性前丁二烯聚合单元中的碳碳双键中的一个碳。The adhesive according to claim 1, wherein the side chain is connected to the carbon atom on the butadiene polymerization unit on the main chain through the sulfur atom at the other end, and the carbon atom is the butadiene before modification. One carbon in the carbon-carbon double bond in the polymerization unit.
  3. 根据权利要求1或2所述的粘结剂，其中，所述侧链的结构式为*-S-R 1-R 2；其中，*表示与主链的连接端；R 1为取代或未取代的亚烷基，取代基为芳基；R 2为-COOLi或-SO 3Li。 The adhesive according to claim 1 or 2, wherein the structural formula of the side chain is *-SR 1 -R 2 ; wherein * represents the connection end to the main chain; R 1 is a substituted or unsubstituted sub Alkyl, the substituent is aryl; R 2 is -COOLi or -SO 3 Li.
  4. 根据权利要求1-3任一项所述的粘结剂，其中，未改性的苯乙烯-丁二烯类聚合物是苯乙烯-丁二烯的无规共聚物或苯乙烯-丁二烯的嵌段共聚物。The adhesive according to any one of claims 1 to 3, wherein the unmodified styrene-butadiene polymer is a random copolymer of styrene-butadiene or styrene-butadiene的block copolymers.
  5. 根据权利要求1-4任一项所述的粘结剂，其中，所述改性聚合物具有如下式(1)或式(2)所示的结构：The binder according to any one of claims 1 to 4, wherein the modified polymer has a structure represented by the following formula (1) or formula (2):
    Figure PCTCN2021099786-appb-100001
    Figure PCTCN2021099786-appb-100001
    其中，所述R 1为取代或未取代的C 1-36的亚烷基，取代基为芳基；R 2为-COOLi或-SO 3Li；m为1-10000之间的整数，n为1-10000之间的整数。 Wherein, the R 1 is a substituted or unsubstituted C 1-36 alkylene group, and the substituent is an aryl group; R 2 is -COOLi or -SO 3 Li; m is an integer between 1 and 10,000, and n is An integer between 1-10000.
  6. 根据权利要求1-5任一项所述的粘结剂，其中，所述的粘结剂还包括水溶性纤维素锂，所述水溶性纤维素锂的加入量为所述改性聚合物质量的0-80％。The binder according to any one of claims 1 to 5, wherein the binder further comprises water-soluble lithium cellulose, and the added amount of the water-soluble lithium cellulose is the mass of the modified polymer Of 0-80%.
  7. 根据权利要求1-6任一项所述的粘结剂，其中，所述粘结剂的剥离强度 为50N/m以上；和/或，所述粘结剂的离子电导率为4×10 -4-5×10 -4S·cm -1。 The adhesive according to any one of claims 1 to 6, wherein the peel strength of the adhesive is 50 N/m or more; and/or the ionic conductivity of the adhesive is 4×10 − 4 -5×10 -4 S·cm -1 .
  8. 一种极片，其中，所述极片包括权利要求1-7任一项所述的粘结剂。A pole piece, wherein the pole piece comprises the adhesive according to any one of claims 1-7.
  9. 根据权利要求8所述的极片，其中，所述极片是通过在集流体一侧或两侧表面涂覆浆料制备得到的，所述浆料包括0.5-5wt％的上述的粘结剂。The pole piece according to claim 8, wherein the pole piece is prepared by coating a slurry on one or both sides of the current collector, and the slurry includes 0.5-5 wt% of the above-mentioned binder .
  10. 一种锂离子电池，所述锂离子电池包括权利要求8或9所述的极片。A lithium ion battery comprising the pole piece according to claim 8 or 9.
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