WO2018068267A1 - 负极添加剂及含有该添加剂的极片和电化学储能装置 - Google Patents

负极添加剂及含有该添加剂的极片和电化学储能装置 Download PDF

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WO2018068267A1
WO2018068267A1 PCT/CN2016/102019 CN2016102019W WO2018068267A1 WO 2018068267 A1 WO2018068267 A1 WO 2018068267A1 CN 2016102019 W CN2016102019 W CN 2016102019W WO 2018068267 A1 WO2018068267 A1 WO 2018068267A1
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group
negative electrode
diisocyanate
substituted
compound
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PCT/CN2016/102019
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English (en)
French (fr)
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钟泽
孙成栋
冯凌云
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宁德新能源科技有限公司
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Priority to CN201680089824.8A priority Critical patent/CN109792040B/zh
Priority to PCT/CN2016/102019 priority patent/WO2018068267A1/zh
Publication of WO2018068267A1 publication Critical patent/WO2018068267A1/zh

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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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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 present application relates to the field of secondary batteries, and in particular to a negative electrode additive and a pole piece and an electrochemical energy storage device containing the same.
  • Lithium-ion batteries have advantages such as high energy density and long cycle life, and are widely used in mobile phones, notebook computers, and digital products.
  • the lithium ion battery is composed of a positive electrode, a negative electrode, a separator and an electrolyte.
  • the positive electrode and the negative electrode are separated by a separator, encapsulated in an aluminum plastic film, and injected into a certain electrolyte to form a lithium ion battery through formation, aging, and the like.
  • the positive electrode active material is usually a metal oxide such as lithium cobaltate, nickel cobalt manganese or nickel cobalt aluminum, and the negative electrode active material is graphite.
  • the pole piece processing of lithium ion batteries has gradually turned to aqueous systems, reducing the use of NMP.
  • the active material is generally graphite, it is stable in water and does not undergo chemical changes, so the water-based anode has become the current mainstream processing method.
  • sodium carboxymethyl cellulose (CMC) is usually used as a thickener and a stabilizer, and styrene-butadiene rubber (SBR) or the like is used as a negative electrode binder.
  • the positive and negative active materials are deposited on the metal foil by coating, and after drying, the active material layer is formed. At this time, the density of the active material layer is small, and the pole piece is thick, which is disadvantageous for the energy density in the lithium ion battery.
  • the roller In the process of cold pressing of the negative electrode piece, in the commonly used aqueous system, since the common CMC and SBR structures have more polar groups such as -OH and -COOH, the roller has a higher bonding force, and The graphite material is soft.
  • the primary object of the present application is to propose a negative electrode additive.
  • a second object of the present application is to provide a negative electrode tab containing the negative electrode additive.
  • a third object of the present application is to provide an electrochemical energy storage device comprising the negative electrode tab.
  • the present application relates to a negative electrode additive containing a compound having an epoxy group or an isocyanate group, and when the negative electrode additive contains a compound having an epoxy group, the epoxy group The compound contains at least two epoxy groups.
  • the epoxy group-containing compound contains at least three epoxy groups.
  • the epoxy group-containing compound has a molar mass of from 100 to 10,000 g/mol.
  • the compound having an isocyanate group contains at least two isocyanate groups.
  • the compound having an epoxy group is selected from the group consisting of:
  • the structural formula of the compound having an epoxy group is as follows:
  • R 11, R 12, R 13, R 14 are each independently selected from substituted or unsubstituted C 1 ⁇ 20 alkylene group, a substituted or unsubstituted alkenyl C 2 ⁇ 20 alkylene group;
  • R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 4 are each independently selected from substituted or unsubstituted C 1-20 alkylene, substituted or unsubstituted alkenyl C 2 ⁇ 20 alkylene group, a substituted or unsubstituted C 6 ⁇ 26 arylene group, a substituted or unsubstituted C 1 ⁇ 20 alkylene group, a substituted or unsubstituted C 6 ⁇ 26 arylene group and an acyl group At least two linked substituents;
  • the substituent is selected from the group consisting of a hydroxyl group, a carboxyl group, a halogen, a C 1-6 linear or branched alkyl group.
  • the epoxy group-containing compound is selected from the group consisting of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, pentaerythritol glycidyl ether, 1,4-butanediol Glycidyl ether, propylene glycol glycidyl ether, glycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, 4,4'-diaminodiphenylmethane tetrahydrate Glyceryl epoxy, triglycidyl p-aminophenol, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, tetraglycidyl-1,3-bis(aminomethylcyclohexane , 9,9-bis[(2,3-epoxypropoxy)phenyl]anthracen
  • the structural formula of the compound having an isocyanate group is as follows:
  • R 5 is selected from substituted or unsubstituted C 1 ⁇ 20 alkylene group, a substituted or unsubstituted C 2 ⁇ 20 alkenylene group, a substituted or unsubstituted C 6 ⁇ 26 arylene group, substituted by a substituted or unsubstituted alkylene of C 1 ⁇ 20 alkyl group, a substituted or unsubstituted C 6 ⁇ 26 are connected in at least two substituent groups of the arylene group and an acyl group;
  • the substituent is selected from the group consisting of a hydroxyl group, a carboxyl group, a halogen, a C 1-6 linear or branched alkyl group.
  • the compound having an isocyanate group is selected from the group consisting of toluene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, and dimethyl group.
  • the negative electrode tab after the addition of the negative electrode additive has a tack roll amount of less than 0.05 g/m 2 at the time of rolling.
  • the application also relates to a negative electrode tab comprising the negative electrode additive of the present application.
  • the content of the negative electrode additive in the negative electrode tab is 0.01% to 2%.
  • the negative electrode tab further comprises a slurry stabilizer selected from the group consisting of sodium carboxymethyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl hydroxyethyl cellulose, and hydroxypropyl group.
  • a slurry stabilizer selected from the group consisting of sodium carboxymethyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl hydroxyethyl cellulose, and hydroxypropyl group.
  • the slurry stabilizer has a redissolution rate of less than 50% in the negative electrode tab.
  • the negative electrode tab further contains a binder selected from the group consisting of styrene-acrylic rubber or a derivative thereof, styrene-butadiene rubber or a derivative thereof, pure propylene rubber or a derivative thereof, nitrile rubber or At least one of a derivative thereof, a chloroprene rubber or a derivative thereof.
  • a binder selected from the group consisting of styrene-acrylic rubber or a derivative thereof, styrene-butadiene rubber or a derivative thereof, pure propylene rubber or a derivative thereof, nitrile rubber or At least one of a derivative thereof, a chloroprene rubber or a derivative thereof.
  • the application also relates to an electrochemical energy storage device comprising the negative electrode tab of the present application.
  • the negative electrode additive of the present application can chemically react with a polar group such as -COOH or -OH on the surface of a slurry stabilizer (CMC) or a binder (SBR), thereby not only reducing the slurry stabilizer (CMC) in the pole piece, The amount of the reactive group of the binder (SBR), the polarity of the negative electrode slurry is lowered, and the structure of the slurry stabilizer (CMC) is changed to bond with the stainless steel roll in the rolling.
  • the negative electrode active material, the binder (SBR), and the like adhere to the surface of the roll, thereby increasing the rolling speed and improving the production efficiency.
  • the present application proposes an additive capable of improving the processing properties of the negative electrode sheet, which can be used with the negative electrode.
  • the reactive functional groups on the surface of the slurry stabilizer (CMC) and binder (SBR) contained in the slurry of the substance react to reduce the active groups of the slurry stabilizer (CMC) and the binder (SBR) in the pole piece.
  • the number of the groups, thereby reducing the adhesion of the negative electrode sheets to the rolls during rolling, can effectively suppress the sticking and falling of the negative electrode sheets during rolling, increase the rolling speed, and improve production efficiency.
  • the negative electrode additive of the present application contains a compound having an epoxy group or an isocyanate group, and when the negative electrode additive contains a compound having an epoxy group, the compound having an epoxy group is at least two epoxy groups. Polyepoxy group compounds.
  • the polyepoxy group compound has a molar mass of from 100 to 10,000 g/mol.
  • the molar mass of the polyepoxy group compound is more preferably 200 to 8000 g/mol.
  • the polyepoxy group compound contains at least three epoxy groups. Preferably, it has 2 to 6 epoxy groups, and further preferably contains 2 to 5 epoxy groups, and its structural formula is represented by Formulas 1 to 4.
  • the number of epoxy groups is larger, it is possible to react with more active groups of the slurry stabilizer (CMC) and the binder (SBR) in the negative electrode active material slurry, while reducing the amount of the additive. Increase the amount of active material to increase the energy density of the battery.
  • the compound having an isocyanate group contains at least two isocyanate groups. More preferably, it contains 2 to 6 isocyanate groups.
  • the polyepoxy group compound may be selected from the group consisting of a glycidyl ether type, a glycidyl ester type or a glycidylamine type, wherein the functional group in the glycidyl ether type is as shown in Formula II, shrinking
  • the functional group in the glyceride type is as shown in Formula III
  • the functional group in the glycidylamine type is as shown in Formula IV:
  • the polyepoxy group compound may be selected from an aliphatic epoxy resin, and the specific structural formula is as shown in Formula IA to Formula IC:
  • R 11, R 12, R 13, R 14 are each independently selected from substituted or unsubstituted C 1 ⁇ 20 alkylene group, a substituted or unsubstituted alkenyl C 2 ⁇ 20 alkylene group; substituents selected from hydroxy , carboxyl, halogen.
  • R 11 , R 12 , R 13 and R 14 are intermediate linking groups, and the epoxy groups are located on the same carbon atom or different carbon atoms of the intermediate linking group, preferably on different carbon atoms.
  • R 11, R 12, R 13, R 14 are each independently selected from substituted or unsubstituted C 6 ⁇ 20 alkylene group, a substituted or unsubstituted C 6 ⁇ 20 alkenylene.
  • the polyepoxy group compound may be selected from the group consisting of glycidyl ether type epoxy compounds, and the specific structural formula is as shown in Formula IIA to IIC:
  • the polyepoxy group compound may be selected from the group consisting of glycidyl ester type epoxy compounds, and the specific structural formula is as shown in Formula IIIA to IIIC:
  • the polyepoxy group compound may be selected from a glycidyl ester type epoxy compound, and the specific structural formula is as shown in Formula IVA:
  • R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 4 are each independently selected from substituted or unsubstituted C 1-20 alkylene groups. , a substituted or unsubstituted C 2 ⁇ 20 alkenylene group, a substituted or unsubstituted C 6 ⁇ 26 arylene group, a substituted or unsubstituted C 1 ⁇ 20 alkylene group, a substituted or unsubstituted C 6 ⁇ 26 a substituent in which at least two of an arylene group and an acyl group are bonded;
  • the substituent is selected from the group consisting of a hydroxyl group, a carboxyl group, a halogen, a C 1-6 linear or branched alkyl group.
  • R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 4 are each independently selected from substituted or unsubstituted C 6-20 alkylene groups, substituted or unsubstituted C 6 ⁇ 20 alkenylene group, a substituted or unsubstituted C 6 ⁇ 26 arylene group, a substituted or unsubstituted C 1 ⁇ 18 alkylene group, a substituted or unsubstituted C 6 ⁇ 26 arylene A substituent formed by linking at least two of the acyl groups.
  • R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 4 are intermediate linking groups, and the epoxy group is located at the same carbon atom or different from the intermediate linking group. On the carbon atom, preferably, on a different carbon atom.
  • the polyepoxy group compound is selected from the group consisting of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, pentaerythritol glycidyl ether, 1, 4 - Butanediol glycidyl ether, propylene glycol glycidyl ether, glycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, 4,4'-diamino Benzene methylene tetraglycidyl epoxy, triglycidyl p-aminophenol, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, tetraglycidyl-1,3-bis (carbam) Cyclohexane), 9,9-bis[(2,3-epoxypropyl ether, 1,4-bis(carb
  • the polyfunctional epoxy compound in the present application can be obtained by reacting NaOH and epichlorohydrin under certain conditions through the corresponding small molecule precursor, and the small molecule precursor can be selected as: bisphenol A, bisphenol F, Bisphenol S, pentaerythritol, 1,4-butanediol, propylene glycol, phthalic acid, phthalic anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydroortho Phthalic anhydride, 4,4'-diaminodiphenylmethane, p-aminophenol, 1,3-dimethylamidocyclohexane, 1,3-Diaminomethylcyclohexane, 9,9-bis(4-hydroxyphenyl)phosphonium 9,9-diphenylfluorene, 1,4-cyclohexanedimethanol, 4,4'-di Aminodiphenyl
  • polyepoxy group compound of the present application may also be selected from:
  • the structural formula of the compound having an isocyanate group is as follows:
  • R 5 is selected from substituted or unsubstituted C 1 ⁇ 20 alkylene group, a substituted or unsubstituted C 2 ⁇ 20 alkenylene group, a substituted or unsubstituted C 6 ⁇ 26 arylene group, substituted by a substituted or unsubstituted alkylene of C 1 ⁇ 20 alkyl group, a substituted or unsubstituted C 6 ⁇ 26 are connected in at least two substituent groups of the arylene group and an acyl group;
  • the substituent is selected from the group consisting of a hydroxyl group, a carboxyl group, a halogen, a C 1-6 linear or branched alkyl group.
  • R 5 is selected from substituted or unsubstituted C 6 ⁇ 20 alkylene group, a substituted or unsubstituted C 6 ⁇ 20 alkenylene group, a substituted or unsubstituted C 6 ⁇ 26 arylene group, a substituted or unsubstituted substituted C 1 ⁇ 18 alkylene group, a substituted or unsubstituted C 6 ⁇ 26 are connected in at least two substituent groups of the arylene group and an acyl group;
  • the substituent is selected from the group consisting of a hydroxyl group, a carboxyl group, a halogen, a C 1-6 linear or branched alkyl group.
  • R 5 is an intermediate linking group
  • the isocyanate groups are located on the same carbon atom or different carbon atoms of the intermediate linking group, preferably on different carbon atoms.
  • the compound having an isocyanate group is selected from the group consisting of toluene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, Dimethylbiphenyl diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, Benzyl diisocyanate, tetramethylbenzene dimethylene diisocyanate, hydrogenated benzene dimethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,4- At least one of cyclohexane diisocyanate, methylcyclohexane diisocyanate, 1,4-benzene diisocyanate
  • the alkylene group having 1 to 20 carbon atoms may be a chain alkylene group or a cycloalkylene group, and the hydrogen group on the ring of the cycloalkylene group may be substituted by an alkyl group.
  • the lower limit of the number of carbon atoms in the alkyl group is preferably 2, 3, 4, 5, and the preferred upper limit is 3, 4, 5, 6, 8, 10, 12, 14, 16, 18.
  • an alkylene group having 1 to 18 carbon atoms is selected, and more preferably, a chain alkylene group having 1 to 12 carbon atoms and a cycloalkylene group having 3 to 8 carbon atoms are selected.
  • a chain alkylene group having 1 to 8 carbon atoms and a cycloalkylene group having 5 to 7 carbon atoms are selected.
  • the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, an anthranylene group, and an anthranylene group.
  • the alkenylene group having 2 to 20 carbon atoms may be a cyclic alkenylene group or a chain alkenylene group. Further, the number of double bonds in the alkenylene group is preferably one.
  • the lower limit of the number of carbon atoms in the alkenylene group is preferably 3, 4, 5, and the preferred upper limit is 3, 4, 5, 6, 8, 10, 12, 14, 16, 18.
  • an alkenylene group having 2 to 18 carbon atoms is selected, and an alkenylene group having 2 to 12 carbon atoms is more preferably selected, and an alkenyl group having 2 to 8 carbon atoms is more preferably selected.
  • alkenyl group examples include a vinylidene group, an allylene group, a pentenylene group, a cyclohexylene group, a cyclohexylene group, and a cyclooctene group.
  • An arylene group having 6 to 26 carbon atoms such as a phenylene group, a phenylene group, an aryl group containing at least one phenylene group such as a biphenylylene group, a fused ring aromatic hydrocarbon group such as a naphthalene group, an anthracene, or a sub
  • the phenanthrene and the fused aromatic hydrocarbon group may be substituted by an alkyl group or an alkenyl group.
  • an arylene group having 6 to 22 carbon atoms is selected, and more preferably, an arylene group having 6 to 16 carbon atoms is selected, and more preferably, an arylene group having 6 to 12 carbon atoms is selected. .
  • aryl group examples include a phenylene group, a benzylidene group, a biphenyl group, a p-terphenylene group, an o-paraphenylene group, and a m-phenylene group.
  • the amount of the bonding roller of the negative electrode tab after the addition of the negative electrode additive is less than 0.05 g/m 2 at the time of rolling.
  • the amount of the adhesive roll refers to the value obtained by dividing the weight of the powder adhered on the stainless steel roll by the area of the negative electrode piece after rolling the negative electrode piece of 1000 m in a stainless steel roll having a diameter of 500 mm. The unit is in g/m 2 .
  • the amount of the bonding roller in the present application is low, and the frequency of the cleaning roller can be reduced within the same cold pressing distance, thereby simplifying the production steps and improving the production efficiency.
  • the application also relates to a negative electrode tab containing the negative electrode additive of the present application.
  • the negative electrode tab contains a slurry stabilizer and a binder; wherein the slurry stabilizer is selected from the group consisting of sodium carboxymethyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl hydroxyethyl cellulose, and hydroxypropyl cellulose. , hydroxypropyl methylcellulose, methyl cellulose, hydroxyethyl methyl cellulose, ethyl cellulose, benzyl cellulose, cyanoethyl cellulose, benzyl cyanoethyl cellulose, phenyl cellulose At least one of them.
  • the binder is at least one selected from the group consisting of styrene-acrylic rubber or a derivative thereof, styrene-butadiene rubber or a derivative thereof, pure propylene rubber or a derivative thereof, nitrile rubber or a derivative thereof, chloroprene rubber or a derivative thereof.
  • the negative electrode additive of the present application can be added at the time of preparation of the negative electrode tab slurry.
  • a negative electrode additive is further added, and the drying process is performed during slurry coating.
  • the negative electrode additive can chemically react with the slurry stabilizer, the polar group such as -COOH, -OH on the surface of the binder, and not only the amount of the active group of the slurry stabilizer and the binder in the pole piece is reduced.
  • the structure of the slurry stabilizer can be changed, the polarity of the negative electrode slurry is lowered, and the adhesion between the stainless steel roll in the rolling is lowered, and the adhesion of graphite, SBR, etc. during the rolling process can be effectively suppressed.
  • the surface of the roller increases the rolling speed and improves production efficiency.
  • the slurry stabilizer re-dissolution rate in the negative electrode tab is less than 50%.
  • the re-dissolution rate of the slurry stabilizer means that after the anode active material slurry is prepared into a pole piece, the active material layer is peeled off, sufficiently dispersed in water, and the content of the slurry stabilizer dissolved in water is measured. .
  • the specific measurement method is as follows: after the anode active material slurry is prepared into a pole piece, the active material layer is peeled off, and 10 g (containing a slurry stabilizer having a weight of M1) is dispersed in 10 g of water, and the dispersion condition is 1500 rpm. Stir for 30 min, sonicate for 15 min (100 W), centrifuge at 6000 rpm for 20 min, and take the supernatant solution, which is a re-dispersible CMC solution. Drying under reduced pressure gave a solid weight m, and the resolubilization rate of the slurry stabilizer was m/M x 100%.
  • the agent re-dissolution rate of the negative electrode tab of the present application is less than 50%, more preferably less than 25%, still more preferably less than 10%.
  • the content of the negative electrode additive in the negative electrode tab is 0.01% to 2%.
  • the addition amount is too low, the degree of bonding with the polar group is insufficient, and the improvement of the processing property is not obvious; and when the addition amount is too large, due to the surface of the slurry stabilizer (CMC) and the binder (SBR)
  • CMC slurry stabilizer
  • SBR binder
  • the application also relates to an electrochemical energy storage device comprising the negative electrode tab of the present application.
  • This embodiment provides a negative electrode additive, and the compound contained in the negative electrode additive and its properties are shown in Table 1:
  • This embodiment provides a negative electrode additive, and the compound contained in the negative electrode additive and its properties are shown in Table 2:
  • the present embodiment provides a negative electrode tab using a negative electrode additive of the present application and a lithium ion battery thereof, the lithium ion battery including a positive electrode tab, a negative electrode tab, a separator, and an electrolyte, and the positive electrode tab includes a cathode current collector and a cathode active material layer.
  • the negative electrode sheet included a negative electrode current collector and a negative electrode active material layer, and the negative electrode current collector was a copper foil having a thickness of 8 ⁇ m. According to the mass fraction, the composition of the active material layer in the negative electrode tab is as shown in Table 3:
  • artificial graphite is used as the active material of the negative electrode and Super P is used as the negative conductive agent.
  • positive electrode tab According to the weight fraction, 96.0% positive active material LiCoO 2 , 2.0% positive electrode binder polyvinylidene fluoride, 2.0% positive electrode conductive agent Super P are added to NMP, stirred evenly, coated in On both sides of a positive electrode current collector aluminum foil (thickness: 14 ⁇ m), a positive electrode sheet was obtained after drying, rolling, slitting, and welding the positive electrode ears.
  • the electrolyte includes an organic solvent and a lithium salt.
  • the organic solvent is a mixture of diethyl carbonate, dimethyl carbonate and ethylene carbonate.
  • the volume ratio of the three organic solvents is 1:1:1, lithium.
  • the salt is LiPF 6 and has a concentration of 1 mol/L.
  • Preparation of the battery winding the positive electrode piece, the negative electrode piece and the separator into a battery core, The battery is placed in an aluminum plastic film, baked and dehydrated, and then injected into the electrolyte to form and age the battery, and the corresponding lithium ion batteries B1 to B7 are obtained.
  • the negative electrode tab was prepared in the same manner as in Example 3 except that the composition of the negative electrode tab was as shown in Table 4:
  • a lithium ion battery was prepared in accordance with the method of Example 3 to obtain corresponding lithium ion batteries BD1 to BD4.
  • the negative electrode tab was prepared in the same manner as in Example 3 except that the composition of the negative electrode tab was as shown in Table 5:
  • a lithium ion battery was prepared in accordance with the method of Example 3 to obtain corresponding lithium ion batteries BD5 to BD7.
  • a 300 mm wide negative electrode sheet was taken and rolled to a certain density under fixed conditions. The rolling length is taken as 1000 m. After rolling, all the powder adhered to the roller is carefully scraped off and weighed, which is the weight of the powder adhered to the roller during rolling. The data is shown in Table 6.
  • the weight of the powder that generates the sticky roll is >30g, which is defined as the sticky roll is very serious;
  • the weight of the powder from which the sticking roller is generated is 15>30g, which is defined as the sticking roller is severe;
  • the sticking weight is defined as the stick weight of ⁇ 15g as the sticking roller is slight.
  • the lithium ion battery was charged to 4.35 V with a constant current of 0.5 C, and charged at a constant voltage to 0.05 C cutoff.
  • the 0.5C constant current discharge was cut to 3.0V, and the discharge capacity was recorded, and the capacity was 100%.
  • the lithium ion battery was charged to 4.35 V with a constant current of 1.0 C, and charged at a constant voltage to 0.05 C cutoff.
  • the lithium ion battery At normal temperature, the lithium ion battery is charged to 4.35V with a constant current of 1.5C, and the constant voltage is charged to 0.05C. 0.5C constant current discharge to 3.0V cutoff, recording discharge capacity, and calculating the percentage.
  • the lithium ion battery At normal temperature, the lithium ion battery is charged to 4.35V with a constant current of 2.0C, and the constant voltage is charged to 0.05C. 0.5C constant current discharge to 3.0V cutoff, recording discharge capacity, and calculating the percentage.
  • the battery has normal electrical properties and can improve its processability.
  • the negative electrode tab has a significant improvement in the sticking roller and the powder drop phenomenon when rolled.
  • the addition amount of the negative electrode additive reaches 0.2% or more, the improvement of the sticky roll and the falling powder has achieved a good effect, and the effect of increasing the amount is not obvious.
  • the amount of addition is too low, the degree of bonding with the polar group is insufficient, and the improvement of the processing property is not obvious; and when the amount of addition is too large, there is no further increase in the polarity of the pole piece, and Affect the energy density of the negative electrode tab and the electrical properties of the battery.
  • the amount of the binder in the comparative example is too large, although the binding force to the active material is stronger, since the binder ratio is high, the adhesion to the roller is also increased at the same time, so that the roller adheres to the roller at the time of rolling. The probability is also increased, and there is no significant improvement in the problem of the sticky roller and the powder drop during rolling, and may even deteriorate.
  • the preparation of the negative electrode tab was carried out by using the other negative electrode additives in Example 1 and Example 2.
  • the performance of the obtained lithium ion battery was similar to that of the experimental example, and is not limited herein.
  • a negative electrode tab was prepared in the same manner as in Example 3 except that the composition of the negative electrode tab was as shown in Table 9:
  • artificial graphite is used as the active material of the negative electrode and Super P is used as the negative conductive agent.
  • the lithium ion battery was prepared according to the method in Example 3, and the corresponding lithium ion battery was obtained.
  • the performance of the obtained lithium ion battery was similar to that of the experimental example, and is not limited herein.

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Abstract

一种负极添加剂及含有该添加剂的极片和电化学储能装置。所述负极添加剂中含有具有环氧基团或异氰酸酯基团的化合物，当负极添加剂中含有具有环氧基团的化合物时，具有环氧基团的化合物中含有至少两个环氧基团。所述负极添加剂可与浆料稳定剂、粘结剂表面的-COOH、-OH等极性基团发生化学反应，不仅减少极片中活性基团的数量，并可使浆料稳定剂的结构发生改变，降低了负极浆料的极性，降低了与辊压中不锈钢辊之间的粘结力，可有效抑制辊压时过程中负极活性物质、粘结剂等粘附到辊的表面，提高辊压速度，提升生产效率。

Description

负极添加剂及含有该添加剂的极片和电化学储能装置 技术领域
本申请涉及二次电池领域，具体讲，涉及一种负极添加剂及含有该添加剂的极片和电化学储能装置。
背景技术
锂离子电池具有高能量密度、长循环寿命等优点，目前已广泛用于移动电话、笔记本电脑、数码产品中。锂离子电池由正极、负极、隔离膜和电解液构成，其中正极、负极中以隔离膜隔开，封装于铝塑膜中，注入一定电解液后通过化成、老化等过程，制作成锂离子电池。其中正极活性材料常采用钴酸锂、镍钴锰、镍钴铝等金属氧化物，负极活性材料为石墨。
随着对环境和成本要求的提升，锂离子电池的极片加工过程，已逐步趋向于水性体系，减少NMP的使用。对于锂离子电池负极，由于其活性材料一般为石墨，在水中稳定存在，不发生化学变化，因此水性负极已经成为目前的主流加工方法。在水性负极极片中，通常采用羧甲基纤维素钠(CMC)作为增稠剂和稳定剂，采用丁苯橡胶(SBR)或者类似乳胶作为负极粘结剂。
锂离子电池极片加工过程中，正、负极活性材料，通过涂布的方式，沉积在金属箔材上，烘干后形成活性物质层。此时活性材料层的密度较小，极片厚，用于锂离子电池中不利于其能量密度。通常，需要采用辊压的方式，将极片压实，降低极片厚度，大大提高锂离子电池的能量密度。在负极极片冷压的过程中，在常用的水性体系中，由于常用的CMC、SBR结构中具有较多-OH、-COOH等极性基团，对辊具有较高的粘结力，且石墨材质软，在辊压时极片表面层的石墨、SBR容易粘附在辊上，造成粘辊和掉粉问题，需要降低辊压速度，且需要定期清理压辊，降低生产效率。
鉴于此，特提出本申请。
发明内容
本申请的首要发明目的在于提出一种负极添加剂。
本申请的第二发明目的在于提出一种含有该负极添加剂的负极极片。
本申请的第三发明目的在于提出一种含有该负极极片的电化学储能装置。
为了完成本申请的目的，采用的技术方案为：
本申请涉及一种负极添加剂，所述负极添加剂中含有具有环氧基团或异氰酸酯基团的化合物，当所述负极添加剂中含有具有环氧基团的化合物时，所述具有环氧基团的化合物中含有至少两个环氧基团。
优选的，所述具有环氧基团的化合物中含有至少三个环氧基团。
优选的，所述具有环氧基团的化合物的摩尔质量为100～10000g/mol。
优选的，所述具有异氰酸酯基团的化合物含有至少两个异氰酸酯基团。
优选的，所述具有环氧基团的化合物选自具有以下基团的化合物：
Figure PCTCN2016102019-appb-000001
优选的，所述具有环氧基团的化合物的结构式如下所示：
Figure PCTCN2016102019-appb-000002
Figure PCTCN2016102019-appb-000003
其中，R11、R12、R13、R14各自独立的分别选自取代或未取代的C1～20亚烷基，取代或未取代的C2～20亚烯基；
R21、R22、R23、R24、R31、R32、R33、R34、R4各自独立的分别选自取代或未取代的C1～20亚烷基，取代或未取代的C2～20亚烯基，取代或未取代的C6～26亚芳基，由取代或未取代的C1～20亚烷基、取代或未取代的C6～26亚芳基和酰基中的至少两种连接而成的取代基；
取代基选自羟基、羧基、卤素、C1～6直链或支链烷基。
优选的，所述具有环氧基团的化合物选自双酚A二缩水甘油醚、双酚F二缩水甘油醚、双酚S二缩水甘油醚、季戊四醇缩水甘油醚、1,4-丁二醇缩水甘油醚、丙二醇缩水甘油醚、苯二甲酸缩水甘油酯、四氢邻苯二甲酸二缩水甘油酯、六氢邻苯二甲酸二缩水甘油酯、4,4’-二氨基二苯甲烷四缩水甘油基环氧、三缩水甘油基对氨基苯酚、1,3-双(N,N-二缩水甘油氨甲基)环己烷、四缩水甘油-1,3-双(氨甲基环己烷)、9,9-二[(2,3-环氧丙氧基)苯基]芴、1,4-环己烷二甲醇二缩水甘油醚、四缩水甘油基-4,4’-二氨基二苯醚、四缩水甘油基-3,4’-二氨基二苯醚中的至少一种。
优选的，所述负极添加剂中含有具有异氰酸酯基团的化合物时，所述具有异氰酸酯基团的化合物的结构式如下所示：
Figure PCTCN2016102019-appb-000004
其中，R5选自取代或未取代的C1～20亚烷基，取代或未取代的C2～20亚烯基，取代或未取代的C6～26亚芳基，由取代或未取代的C1～20亚烷基、取代或未取代的C6～26亚芳基和酰基中的至少两种连接而成的取代基；
取代基选自羟基、羧基、卤素、C1～6直链或支链烷基。
优选的，所述负极添加剂中含有具有异氰酸酯基团的化合物时，所述具有异氰酸酯基团的化合物选自甲苯二异氰酸酯、二苯基甲烷二异氰酸酯、1,5-萘二异氰酸酯、二甲基联苯二异氰酸酯、六亚甲基二异氰酸酯、2,2,4-三甲基己二异氰酸酯、2,4,4-三甲基己二异氰酸酯、苯二甲基二异氰酸酯、四甲基苯二亚甲基二异氰酸酯、氢化苯二亚甲基二异氰酸酯、异佛尔酮二异氰酸酯、4,4′-二环己基甲烷二异氰酸酯、1,4-环己烷二异氰酸酯、 甲基环己烷二异氰酸酯、1,4苯二异氰酸酯、降冰片烷二异氰酸酯中的至少一种。
优选的，其特征在于，添加有所述负极添加剂后的负极极片在辊压时的粘辊量小于0.05g/m2。本申请还涉及一种含有本申请负极添加剂的负极极片。
优选的，所述负极添加剂在所述负极极片中的质量百分比含量为0.01％～2％。
优选的，所述负极极片中还含有浆料稳定剂，所述浆料稳定剂选自羧甲基纤维素钠、羟乙基纤维素、羧甲基羟乙基纤维素钠、羟丙基纤维素、羟丙基甲基纤维素、甲基纤维素、羟乙基甲基纤维素、乙基纤维素、苄基纤维素、氰乙基纤维素、苄基氰乙基纤维素、苯基纤维素中的至少一种。
优选的，所述负极极片中浆料稳定剂再溶解率小于50％。
优选的，所述负极极片中还含有粘结剂，所述粘结剂选自苯丙橡胶或其衍生物、丁苯橡胶或其衍生物、纯丙橡胶或其衍生物、丁腈橡胶或其衍生物、氯丁橡胶或其衍生物中的至少一种。
本申请还涉及一种电化学储能装置，含有本申请的负极极片。
本申请的技术方案至少具有以下有益的效果：
本申请的负极添加剂可与浆料稳定剂(CMC)、粘结剂(SBR)表面的-COOH、-OH等极性基团发生化学反应，不仅减少极片中浆料稳定剂(CMC)、粘结剂(SBR)的活性基团的数量，负极浆料的极性降低，并可使浆料稳定剂(CMC)的结构发生改变，从而与辊压中的不锈钢辊之间的粘结力降低，有效抑制辊压时过程中负极活性物质、粘结剂(SBR)等粘附到辊的表面，提高辊压速度，提升生产效率。
下面结合具体实施例，进一步阐述本申请。应理解，这些实施例仅用于说明本申请而不用于限制本申请的范围。
具体实施方式
本申请提出了一种能够改善负极极片加工性能的添加剂，可与负极活 性物质浆料中含有的浆料稳定剂(CMC)、粘结剂(SBR)等表面的活性官能团发生反应，减少极片中浆料稳定剂(CMC)、粘结剂(SBR)的活性基团的数量，从而降低负极极片在辊压时与辊的粘结力，可以有效抑制辊压时负极极片粘辊和掉粉，提高辊压速度，提升生产效率。本申请的负极添加剂中含有具有环氧基团或异氰酸酯基团的化合物，当负极添加剂中含有具有环氧基团的化合物时，具有环氧基团的化合物为含有至少两个环氧基团的多环氧基团化合物。
作为本申请负极添加剂的一种改进，多环氧基团化合物的摩尔质量为100～10000g/mol。如果化合物的分子量过大，则粘度过大，不易在水性负极活性物质浆料中进行分散，且反应效率较低；多环氧基团化合物的摩尔质量进一步优选为200～8000g/mol。
作为本申请负极添加剂的一种改进，多环氧基团化合物中含有至少三个环氧基团。优选的，含有2～6个环氧基团，进一步优选的，含有2～5个环氧基团，其结构通式如式1～式4所示。当环氧基团的个数越多，则能够与负极活性物质浆料中更多的浆料稳定剂(CMC)、粘结剂(SBR)的活性基团进行反应，同时减少添加剂的使用量，增加活性物质的用量，从而提高电池的能量密度。
Figure PCTCN2016102019-appb-000005
Figure PCTCN2016102019-appb-000006
作为本申请负极添加剂的一种改进，具有异氰酸酯基团的化合物含有至少两个异氰酸酯基团。进一步优选含有2～6个异氰酸酯基团。
作为本申请负极添加剂的一种改进，多环氧基团化合物可选自缩水甘油醚型、缩水甘油酯型或缩水甘油胺型，其中缩水甘油醚型中的官能团为如式II所示，缩水甘油酯型中的官能团为如式III所示，缩水甘油胺型中的官能团为如式IV所示：
Figure PCTCN2016102019-appb-000007
作为本申请负极添加剂的一种改进，多环氧基团化合物可选自脂肪族型环氧树脂，具体结构式如式IA～式IC所示：
Figure PCTCN2016102019-appb-000008
其中，R11、R12、R13、R14各自独立的分别选自取代或未取代的C1～20亚烷基，取代或未取代的C2～20亚烯基；取代基选自羟基、羧基、卤素。
其中，R11、R12、R13、R14作为中间连接基团，环氧基团位于中间连接基团的同一个碳原子或不同的碳原子上，优选的，位于不同的碳原子上。
优选的，R11、R12、R13、R14各自独立的分别选自取代或未取代的C6～ 20亚烷基，取代或未取代的C6～20亚烯基。
作为本申请负极添加剂的一种改进，多环氧基团化合物可选自缩水甘油醚型环氧化合物，具体结构式如式IIA～式IIC所示：
Figure PCTCN2016102019-appb-000009
作为本申请负极添加剂的一种改进，多环氧基团化合物可选自缩水甘油酯型环氧化合物，具体结构式如式IIIA～式IIIC所示：
Figure PCTCN2016102019-appb-000010
作为本申请负极添加剂的一种改进，多环氧基团化合物可选自缩水甘油酯型环氧化合物，具体结构式如式IVA所示：
Figure PCTCN2016102019-appb-000011
在以上通式中，R21、R22、R23、R24、R31、R32、R33、R34、R4各自独立的分别选自取代或未取代的C1～20亚烷基，取代或未取代的C2～20亚烯基，取代或未取代的C6～26亚芳基，由取代或未取代的C1～20亚烷基、取代或未取代的C6～26亚芳基和酰基中的至少两种连接而成的取代基；
取代基选自羟基、羧基、卤素、C1～6直链或支链烷基。
优选的，R21、R22、R23、R24、R31、R32、R33、R34、R4各自独立的分别选自取代或未取代的C6～20亚烷基，取代或未取代的C6～20亚烯基，取代或未取代的C6～26亚芳基，由取代或未取代的C1～18亚烷基、取代或未取代的C6～26亚芳基和酰基中的至少两种连接而成的取代基。
其中，R21、R22、R23、R24、R31、R32、R33、R34、R4作为中间连接基团，环氧基团位于中间连接基团的同一个碳原子或不同的碳原子上，优选的，位于不同的碳原子上。
作为本申请负极添加剂的一种改进，多环氧基团化合物选自双酚A二缩水甘油醚、双酚F二缩水甘油醚、双酚S二缩水甘油醚、季戊四醇缩水甘油醚、1,4-丁二醇缩水甘油醚、丙二醇缩水甘油醚、苯二甲酸缩水甘油酯、四氢邻苯二甲酸二缩水甘油酯、六氢邻苯二甲酸二缩水甘油酯、4,4’-二氨基二苯甲烷四缩水甘油基环氧、三缩水甘油基对氨基苯酚、1,3-双(N,N-二缩水甘油氨甲基)环己烷、四缩水甘油-1,3-双(氨甲基环己烷)、9,9-二[(2,3-环氧丙氧基)苯基]芴、1,4-环己烷二甲醇二缩水甘油醚、四缩水甘油基-4,4’-二氨基二苯醚、四缩水甘油基-3,4’-二氨基二苯醚中的至少一种。
本申请中的多官能团环氧化合物，可以通过相应的小分子前躯体，与NaOH、环氧氯丙烷在一定条件下反应得到，其小分子前躯体可选为：双酚A、双酚F、双酚S、季戊四醇、1,4-丁二醇、丙二醇、苯二甲酸、苯二甲酸酐、四氢邻苯二甲酸、四氢邻苯二甲酸酐、六氢邻苯二甲酸、六氢邻苯二甲酸酐、4,4'-二氨基二苯甲烷、对氨基苯酚、1，3-二甲酰胺基环己烷、 1,3-二氨甲基环己烷、9,9-双(4-羟苯基)芴9,9-二苯基芴、1,4-环己烷二甲醇、4,4’-二氨基二苯醚、3,4’-二氨基二苯醚。
除以上具体化合物外，本申请中多环氧基团化合物还可选自：
Figure PCTCN2016102019-appb-000012
作为本申请负极添加剂的一种改进，当负极添加剂中含有具有异氰酸酯基团的化合物时，具有异氰酸酯基团的化合物的结构式如下所示：
Figure PCTCN2016102019-appb-000013
其中，R5选自取代或未取代的C1～20亚烷基，取代或未取代的C2～20亚烯基，取代或未取代的C6～26亚芳基，由取代或未取代的C1～20亚烷基、取代或未取代的C6～26亚芳基和酰基中的至少两种连接而成的取代基；
取代基选自羟基、羧基、卤素、C1～6直链或支链烷基。
优选的，R5选自取代或未取代的C6～20亚烷基，取代或未取代的C6～20亚烯基，取代或未取代的C6～26亚芳基，由取代或未取代的C1～18亚烷基、取代或未取代的C6～26亚芳基和酰基中的至少两种连接而成的取代基；
取代基选自羟基、羧基、卤素、C1～6直链或支链烷基。
其中，R5作为中间连接基团，异氰酸酯基团位于中间连接基团的同一个碳原子或不同的碳原子上，优选的，位于不同的碳原子上。
作为本申请负极添加剂的一种改进，当负极添加剂中含有具有异氰酸酯基团的化合物时，具有异氰酸酯基团的化合物选自甲苯二异氰酸酯、二苯基甲烷二异氰酸酯、1,5-萘二异氰酸酯、二甲基联苯二异氰酸酯、六亚甲基二异氰酸酯、2,2,4-三甲基己二异氰酸酯、2,4,4-三甲基己二异氰酸酯、 苯二甲基二异氰酸酯、四甲基苯二亚甲基二异氰酸酯、氢化苯二亚甲基二异氰酸酯、异佛尔酮二异氰酸酯、4,4′-二环己基甲烷二异氰酸酯、1,4-环己烷二异氰酸酯、甲基环己烷二异氰酸酯、1,4苯二异氰酸酯、降冰片烷二异氰酸酯中的至少一种。
在本申请的上述通式中：
碳原子数为1～20的亚烷基，亚烷基可为链状亚烷基，也可为环亚烷基，位于环亚烷基的环上的氢可被烷基取代，所述亚烷基中碳原子数优选的下限值为2，3，4，5，优选的上限值为3，4，5，6，8，10，12，14，16，18。优选地，选择碳原子数为1～18的亚烷基，进一步优选地，选择碳原子数为1～12的链状亚烷基，碳原子数为3～8的环亚烷基，更进一步优选地，选择碳原子数为1～8的链状亚烷基，碳原子数为5～7的环亚烷基。作为亚烷基的实例，具体可以举出：亚甲基、亚乙基、亚丙基、亚丁基、亚戊基、亚己基、亚庚基、亚辛基、亚壬基、亚癸基。
碳原子数为2～20的亚烯基可为环状亚烯基，也可为链状亚烯基。另外，亚烯基中双键的个数优选为1个。所述亚烯基中碳原子数优选的下限值为3，4，5，优选的上限值为3，4，5，6，8，10，12，14，16，18。优选地，选择碳原子数为2～18的亚烯基，进一步优选地，选择碳原子数为2～12的亚烯基，更进一步优选地，选择碳原子数为2～8的烯基。作为烯基的实例，具体可以举出：亚乙烯基、亚烯丙基、亚戊烯基、亚环己烯基、亚环庚烯基、亚环辛烯基。
碳原子数为6～26的亚芳基，例如亚苯基、亚苯烷基、至少含有一个亚苯基的芳基如亚联苯基、亚稠环芳烃基如亚萘、亚蒽、亚菲均可，联苯基和稠环芳烃基还可被烷基或是烯基所取代。优选地，选择碳原子数为6～22的亚芳基，进一步优选地，选择碳原子数为6～16的亚芳基，更进一步优选地，选择碳原子数为6～12的亚芳基。作为芳基的实例，具体可以举出：亚苯基、亚苄基、联苯基、对甲亚苯基、邻甲亚苯基、间甲亚苯基。
作为本申请负极添加剂的一种改进，添加负极添加剂后的负极极片在辊压时的粘辊量小于0.05g/m2。在本申请中，粘辊量是指用直径为500mm 不锈钢辊在对1000米长的负极极片进行辊压后，不锈钢辊上所粘有的粉体的重量除以负极极片面积所得的值，单位以g/m2计。本申请中的粘辊量低，在相同的冷压距离内，可减少清理辊的频率，从而可简化生产步骤，提高生产效率。
本申请还涉及一种负极极片，其中含有本申请的负极添加剂。负极极片中含有浆料稳定剂和粘结剂；其中，浆料稳定剂选自羧甲基纤维素钠、羟乙基纤维素、羧甲基羟乙基纤维素钠、羟丙基纤维素、羟丙基甲基纤维素、甲基纤维素、羟乙基甲基纤维素、乙基纤维素、苄基纤维素、氰乙基纤维素、苄基氰乙基纤维素、苯基纤维素中的至少一种。粘结剂选自苯丙橡胶或其衍生物、丁苯橡胶或其衍生物、纯丙橡胶或其衍生物、丁腈橡胶或其衍生物、氯丁橡胶或其衍生物中的至少一种。
作为本申请负极极片的一种改进，可在负极极片浆料的制备时，加入本申请的负极添加剂。例如，在水性负极极片浆料的搅拌过程中，在含有石墨、浆料稳定剂、粘结剂、水的混合浆料的基础上，再加入负极添加剂，在浆料涂布时烘干过程中，负极添加剂可与浆料稳定剂、粘结剂表面的-COOH、-OH等极性基团发生化学反应，不仅减少极片中浆料稳定剂、粘结剂的活性基团的数量，并可使浆料稳定剂的结构发生改变，负极浆料的极性降低，与辊压中的不锈钢辊之间的粘结力降低，可以有效抑制辊压时过程中石墨、SBR等粘附到辊的表面，提高辊压速度，提升生产效率。
作为本申请负极极片的一种改进，负极极片中浆料稳定剂再溶解率小于50％。本申请中，浆料稳定剂的再溶解率是指当负极活性物质浆料制备成极片后，再将活性物质层剥离，充分分散于水中，测定再溶解于水中的浆料稳定剂的含量。
具体的测定方法为：指当负极活性物质浆料制备成极片后，再将活性物质层剥离，称量10g(其中含有重量为M1的浆料稳定剂)分散到10g水中，分散条件为1500rpm搅拌30min，超声15min(100W)，在6000rpm下离心20min，取上层清液，即为可再次分散的CMC溶液。减压下烘干，所得到固体重量m，浆料稳定剂的再溶解率＝m/M×100％。本申请负极极片的剂再溶解率小于50％，更优选小于25％，更优选小于10％。
作为本申请负极极片的一种改进，负极添加剂在负极极片中的质量百分比含量为0.01％～2％。而当其添加量过低，与极性基团的结合程度不够，对加工性能的改善不明显；而当其添加量过大，由于浆料稳定剂(CMC)、粘结剂(SBR)表面极性基团数量有限，添加过多负极添加剂时会有富余部分，对极片极性的降低无进一步增加的趋势，且还会影响负极极片的能量密度，且会影响电池性能。
本申请还涉及一种电化学储能装置，含有本申请的负极极片。
实施例1
本实施例提供一种负极添加剂，该负极添加剂中含有的化合物及其性质如表1所示：
表1：
Figure PCTCN2016102019-appb-000014
实施例2
本实施例提供一种负极添加剂，该负极添加剂中含有的化合物及其性质如表2所示：
表2：
编号 化合物 异氰酸酯基个数
1 甲苯二异氰酸酯 2
2 二苯基甲烷二异氰酸酯 2
3 1,5‐萘二异氰酸酯 2
4 二甲基联苯二异氰酸酯 2
5 六亚甲基二异氰酸酯 2
6 苯二甲基二异氰酸酯 2
7 2,2,4‐三甲基己二异氰酸酯 2
8 四甲基苯二亚甲基二异氰酸 2
9 甲基环己烷二异氰酸酯 2
10 1,4‐环己烷二异氰酸酯 2
11 4,4′‐二环己基甲烷二异氰酸酯 2
12 降冰片烷二异氰酸酯 2
实施例3
本实施例提供使用本申请负极添加剂的负极极片及其锂离子电池，锂离子电池包括正极极片、负极极片、隔离膜和电解液，正极极片包括正极集流体和正极活性物质层。
负极片包括负极集流体和负极活性物质层，负极集流体是铜箔，厚度为8μm。按照质量分数，负极极片中活性物质层的组成如表3所示：
表3：
Figure PCTCN2016102019-appb-000015
Figure PCTCN2016102019-appb-000016
其中：负极活性物质选用人造石墨，负极导电剂选用Super P。
锂离子电池的制备：
1、正极极片的制备：按重量分数计，将96.0％正极活性物质LiCoO2、2.0％正极粘结剂聚偏氟乙烯、2.0％正极导电剂Super P加入NMP中，搅拌均匀，涂覆在正极集流体铝箔(厚度为14μm)的两面上，经过干燥、辊压、分切、焊接正极耳后得到正极片。
2、负极极片的制备：按表3所示的组分，加入蒸馏水中搅拌均匀，涂覆在铜箔上，涂覆在负极集流体铜箔(厚度为10μm)的两面上；经过干燥、辊压、分切、焊接负极耳后得到负极片。
3、电解液的制备：电解液包括有机溶剂和锂盐，有机溶剂为碳酸二乙酯、碳酸二甲酯、碳酸乙烯酯的混合物，三种有机溶剂的体积比为1:1:1，锂盐为LiPF6，浓度为1mol/L。
4、电池的制备：将正极极片、负极极片以及隔离膜卷绕成电芯，将 电芯置于铝塑膜中，烘烤除水，再注入电解液，对电芯进行化成和老化，得到相应的锂离子电池B1～B7。
对比例1：
按照实施例3中的方法制备负极极片，区别在于负极极片的组成如表4所示：
表4：
Figure PCTCN2016102019-appb-000017
按照实施例3中的方法制备锂离子电池，得到相应的锂离子电池BD1～BD4。
对比例2：
按照实施例3中的方法制备负极极片，区别在于负极极片的组成如表5所示：
表5：
Figure PCTCN2016102019-appb-000018
Figure PCTCN2016102019-appb-000019
按照实施例3中的方法制备锂离子电池，得到相应的锂离子电池BD5～BD7。
实验例
本申请实施例中锂离子电池的性能测试的检测方法为：
(1)负极片辊压时粘辊量
取300mm宽的负极片，在固定条件下辊压到一定的密度。辊压长度取1000m，辊压后，仔细将辊上粘附的所有粉体刮下，称重，即为辊压时粘附在辊上的粉料重量。数据见表6。
其中，以发生粘辊的粉料重量为>30g定义为粘辊非常严重；
以发生粘辊的粉料重量为15>30g定义为粘辊严重；
以发生粘辊的粉料重量为<15g定义为粘辊轻微。
(2)极片中可再次溶解的CMC浓度
取辊压后的负极极片，将表面的活性材料刮下，称量10g分散到10g水中，1500rpm搅拌30min，超声15min(100W)，在6000rpm下离心20min，取上层清液，即为可再次分散的CMC溶液。减压下烘干，所得到固体重量m，为可再次分散的CMC，计算可再次分散的CMC溶液浓度为m/10(wt％)。数据见表7。
(3)锂离子电池的放电倍率性能测试
常温下，将锂离子电池以0.5C恒流充电到4.35V，恒压充电至0.05C截止。0.5C恒流放电至3.0V截止，记录放电容量，以此容量为100％。
常温下，将锂离子电池以1.0C恒流充电到4.35V，恒压充电至0.05C截止。0.5C恒流放电至3.0V截止，记录放电容量，计算百分比。
常温下，将锂离子电池以1.5C恒流充电到4.35V，恒压充电至0.05C截止。0.5C恒流放电至3.0V截止，记录放电容量，计算百分比。
常温下，将锂离子电池以2.0C恒流充电到4.35V，恒压充电至0.05C截止。0.5C恒流放电至3.0V截止，记录放电容量，计算百分比。
数据见表8。
表6：负极片的粘辊粉料重量
电池编号 辊上粘附的粉料重量g 粘辊严重程度
BD1 42.7 非常严重
BD2 40.1 非常严重
BD3 39.2 非常严重
BD4 38.5 非常严重
BD5 33.2 非常严重
BD6 13.7 轻微
BD7 19.2 严重
B1 28.8 严重
B2 11.5 轻微
B3 9.7 轻微
B4 10.4 轻微
B5 9.9 轻微
B6 10.7 轻微
B7 11.5 轻微
表7：极片中可再次溶解的CMC浓度
Figure PCTCN2016102019-appb-000020
Figure PCTCN2016102019-appb-000021
表8：电池放电倍率性能
电池编号 0.5C 1.0C 1.5C 2.0C
BD1 100.00％ 93.95％ 79.33％ 54.80％
BD2 100.00％ 93.89％ 79.15％ 54.47％
BD3 100.00％ 93.37％ 77.51％ 51.60％
BD4 100.00％ 92.96％ 76.27％ 49.47％
BD5 100.00％ 93.83％ 78.96％ 54.14％
BD6 100.00％ 92.21％ 74.01％ 45.75％
BD7 100.00％ 92.61％ 75.22％ 47.72％
B1 100.00％ 92.67％ 79.34％ 55.43％
B2 100.00％ 92.31％ 79.07％ 54.76％
B3 100.00％ 91.95％ 77.42％ 52.53％
B4 100.00％ 90.31％ 75.96％ 50.38％
B5 100.00％ 92.95％ 78.70％ 54.67％
B6 100.00％ 91.86％ 78.79％ 54.95％
B7 100.00％ 91.31％ 79.09％ 55.81％
如上表数据所示，将本申请中的添加剂应用于锂离子电池的负极极片中时，电池电性能正常，可改善其加工性能。添加本申请的负极添加剂后，负极极片在辊压时，粘辊、掉粉现象有明显的改善。
当对比例中使用仅含有一个环氧基团的化合物时，由于环氧基团较少，反应能力差，与浆料稳定剂(CMC)、粘结剂(SBR)反应效率更低，因此对辊压时粘辊、掉粉改善效果较差。
当负极添加剂的添加量达到0.2％以上时，对粘辊、掉粉的改善已经达到较好的效果，增加用量效果不明显。而当其添加量过低，与极性基团的结合程度不够，对加工性能的改善不明显；而当其添加量过大，对极片极性的降低无进一步增加的趋势，且还会影响负极极片的能量密度及电池的电性能。
通过添加改善加工的水性负极添加剂，CMC表面活性基团参与反应，CMC的水溶性降低，可再次分散到水中的CMC的量大大降低。
当对比例中粘合剂用量过大时，虽然对活性物质的粘结力更强，但是由于粘合剂比例高，对辊的粘结力也同时增加，因此辊压时粘附在辊上的几率也增加，对辊压时的粘辊、掉粉问题无明显改善，甚至可能恶化。
采用实施例1和实施例2中的其他负极添加剂进行负极极片的制备，获得的锂离子电池的性能与实验例相似，限于篇幅，不再赘述。
实施例4
按照实施例3中的方法制备负极极片，区别在于负极极片的组成如表9所示：
表9：
Figure PCTCN2016102019-appb-000022
Figure PCTCN2016102019-appb-000023
其中：负极活性物质选用人造石墨，负极导电剂选用Super P。
按照实施例3中的方法制备锂离子电池，得到相应的锂离子电池，获得的锂离子电池的性能与实验例相似，限于篇幅，不再赘述。
本申请虽然以较佳实施例公开如上，但并不是用来限定权利要求，任何本领域技术人员在不脱离本申请构思的前提下，都可以做出若干可能的变动和修改，因此本申请的保护范围应当以本申请权利要求所界定的范围为准。

Claims (16)

  1. 一种负极添加剂，其特征在于，所述负极添加剂中含有具有环氧基团或异氰酸酯基团的化合物，当所述负极添加剂中含有具有环氧基团的化合物时，所述具有环氧基团的化合物中含有至少两个环氧基团。
  2. 根据权利要求1所述的负极添加剂，其特征在于，所述具有环氧基团的化合物中含有至少三个环氧基团。
  3. 根据权利要求1所述的负极添加剂，其特征在于，所述具有环氧基团的化合物的摩尔质量为100～10000g/mol。
  4. 根据权利要求1所述的负极添加剂，其特征在于，所述具有异氰酸酯基团的化合物含有至少两个异氰酸酯基团。
  5. 根据权利要求1所述的负极添加剂，其特征在于，所述具有环氧基团的化合物选自具有以下基团的化合物：
    Figure PCTCN2016102019-appb-100001
  6. 根据权利要求1所述的负极添加剂，其特征在于，所述具有环氧基团的化合物的结构式如下所示：
    Figure PCTCN2016102019-appb-100002
    Figure PCTCN2016102019-appb-100003
    其中，R11、R12、R13、R14各自独立的分别选自取代或未取代的C1～20亚烷基，取代或未取代的C2～20亚烯基；
    R21、R22、R23、R24、R31、R32、R33、R34、R4各自独立的分别选自取代或未取代的C1～20亚烷基，取代或未取代的C2～20亚烯基，取代或未取代 的C6～26亚芳基，由取代或未取代的C1～20亚烷基、取代或未取代的C6～26亚芳基和酰基中的至少两种连接而成的取代基；
    取代基选自羟基、羧基、卤素、C1～6直链或支链烷基。
  7. 根据权利要求1所述的负极添加剂，其特征在于，所述具有环氧基团的化合物选自双酚A二缩水甘油醚、双酚F二缩水甘油醚、双酚S二缩水甘油醚、季戊四醇缩水甘油醚、1,4-丁二醇缩水甘油醚、丙二醇缩水甘油醚、苯二甲酸缩水甘油酯、四氢邻苯二甲酸二缩水甘油酯、六氢邻苯二甲酸二缩水甘油酯、4,4’-二氨基二苯甲烷四缩水甘油基环氧、三缩水甘油基对氨基苯酚、1,3-双(N,N-二缩水甘油氨甲基)环己烷、四缩水甘油-1,3-双(氨甲基环己烷)、9,9-二[(2,3-环氧丙氧基)苯基]芴、1,4-环己烷二甲醇二缩水甘油醚、四缩水甘油基-4,4’-二氨基二苯醚、四缩水甘油基-3,4’-二氨基二苯醚中的至少一种。
  8. 根据权利要求1所述的负极添加剂，其特征在于，所述负极添加剂中含有具有异氰酸酯基团的化合物时，所述具有异氰酸酯基团的化合物的结构式如下所示：
    Figure PCTCN2016102019-appb-100004
    其中，R5选自取代或未取代的C1～20亚烷基，取代或未取代的C2～20亚烯基，取代或未取代的C6～26亚芳基，由取代或未取代的C1～20亚烷基、取代或未取代的C6～26亚芳基和酰基中的至少两种连接而成的取代基；
    取代基选自羟基、羧基、卤素、C1～6直链或支链烷基。
  9. 根据权利要求1所述的负极添加剂，其特征在于，所述负极添加剂中含有具有异氰酸酯基团的化合物时，所述具有异氰酸酯基团的化合物选自甲苯二异氰酸酯、二苯基甲烷二异氰酸酯、1,5-萘二异氰酸酯、二甲基联苯二异氰酸酯、六亚甲基二异氰酸酯、2,2,4-三甲基己二异氰酸酯、2,4,4-三甲基己二异氰酸酯、苯二甲基二异氰酸酯、四甲基苯二亚甲基二异氰酸酯、氢化苯二亚甲基二异氰酸酯、异佛尔酮二异氰酸酯、4,4′-二环己基甲烷二异氰酸酯、1,4-环己烷二异氰酸酯、甲基环己烷二异氰酸酯、1,4苯二异氰酸酯、降冰片烷二异氰酸酯中的至少一种。
  10. 根据权利要求1～9任一所述的负极添加剂，其特征在于，添加有所述负极添加剂后的负极极片在辊压时的粘辊量小于0.05g/m2。
  11. 一种含有如权利要求1～10任一所述负极添加剂的负极极片。
  12. 根据权利要求11所述的负极极片，其特征在于，所述负极添加剂在所述负极极片中的质量百分比含量为0.01％～2％。
  13. 根据权利要求11所述的负极极片，其特征在于，所述负极极片中还含有浆料稳定剂，所述浆料稳定剂选自羧甲基纤维素钠、羟乙基纤维素、羧甲基羟乙基纤维素钠、羟丙基纤维素、羟丙基甲基纤维素、甲基纤维素、羟乙基甲基纤维素、乙基纤维素、苄基纤维素、氰乙基纤维素、苄基氰乙基纤维素、苯基纤维素中的至少一种。
  14. 根据权利要求13所述的负极极片，其特征在于，所述负极极片中浆料稳定剂再溶解率小于50％。
  15. 根据权利要求11所述的负极极片，其特征在于，所述负极极片中还含有粘结剂，所述粘结剂选自苯丙橡胶或其衍生物、丁苯橡胶或其衍生物、纯丙橡胶或其衍生物、丁腈橡胶或其衍生物、氯丁橡胶或其衍生物中的至少一种。
  16. 一种电化学储能装置，其特征在于，所述电化学储能装置中含有如权利要求11～15中任一权利要求所述的负极极片。
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