CN116404166A - Negative electrode binder, battery negative electrode containing same, lithium ion battery core and lithium ion battery - Google Patents
Negative electrode binder, battery negative electrode containing same, lithium ion battery core and lithium ion battery Download PDFInfo
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- CN116404166A CN116404166A CN202310578745.5A CN202310578745A CN116404166A CN 116404166 A CN116404166 A CN 116404166A CN 202310578745 A CN202310578745 A CN 202310578745A CN 116404166 A CN116404166 A CN 116404166A
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- lithium ion
- polyrotaxane
- ion battery
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- 239000011883 electrode binding agent Substances 0.000 title claims abstract description 67
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 54
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 50
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims abstract description 32
- 239000001768 carboxy methyl cellulose Substances 0.000 claims abstract description 32
- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims abstract description 31
- 239000008112 carboxymethyl-cellulose Substances 0.000 claims abstract description 31
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 15
- 229910052710 silicon Inorganic materials 0.000 claims description 15
- 229920003048 styrene butadiene rubber Polymers 0.000 claims description 15
- 239000010703 silicon Substances 0.000 claims description 14
- 239000003792 electrolyte Substances 0.000 claims description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 8
- 239000002033 PVDF binder Substances 0.000 claims description 8
- 239000006258 conductive agent Substances 0.000 claims description 8
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 8
- 239000007773 negative electrode material Substances 0.000 claims description 7
- 239000010405 anode material Substances 0.000 claims description 5
- 239000002131 composite material Substances 0.000 claims description 5
- 239000006183 anode active material Substances 0.000 claims description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 4
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 claims description 3
- 239000011884 anode binding agent Substances 0.000 claims description 3
- 239000011866 silicon-based anode active material Substances 0.000 claims description 3
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 2
- 229920001400 block copolymer Polymers 0.000 claims description 2
- 239000004917 carbon fiber Substances 0.000 claims description 2
- 239000002041 carbon nanotube Substances 0.000 claims description 2
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 2
- 229910021389 graphene Inorganic materials 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 239000005543 nano-size silicon particle Substances 0.000 claims description 2
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 2
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 2
- 239000002153 silicon-carbon composite material Substances 0.000 claims description 2
- 239000007858 starting material Substances 0.000 claims 1
- 239000002210 silicon-based material Substances 0.000 abstract description 12
- 230000000694 effects Effects 0.000 abstract description 7
- 229920002125 Sokalan® Polymers 0.000 description 34
- KFSLWBXXFJQRDL-UHFFFAOYSA-N peroxyacetic acid Substances CC(=O)OO KFSLWBXXFJQRDL-UHFFFAOYSA-N 0.000 description 33
- 238000002360 preparation method Methods 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 14
- 239000002174 Styrene-butadiene Substances 0.000 description 10
- 238000000034 method Methods 0.000 description 7
- 230000001070 adhesive effect Effects 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 239000011856 silicon-based particle Substances 0.000 description 6
- 239000000853 adhesive Substances 0.000 description 5
- 238000004132 cross linking Methods 0.000 description 5
- 238000007792 addition Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 2
- 239000003431 cross linking reagent Substances 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 description 2
- 239000003999 initiator Substances 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 239000003607 modifier Substances 0.000 description 2
- 229920001223 polyethylene glycol Polymers 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- XOAAWQZATWQOTB-UHFFFAOYSA-N taurine Chemical compound NCCS(O)(=O)=O XOAAWQZATWQOTB-UHFFFAOYSA-N 0.000 description 2
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 description 1
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 239000011837 N,N-methylenebisacrylamide Substances 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 1
- 239000011203 carbon fibre reinforced carbon Substances 0.000 description 1
- 125000002057 carboxymethyl group Chemical group [H]OC(=O)C([H])([H])[*] 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 238000007334 copolymerization reaction Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- JCCYXJAEFHYHPP-OLXYHTOASA-L dilithium;(2r,3r)-2,3-dihydroxybutanedioate Chemical compound [Li+].[Li+].[O-]C(=O)[C@H](O)[C@@H](O)C([O-])=O JCCYXJAEFHYHPP-OLXYHTOASA-L 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 235000010299 hexamethylene tetramine Nutrition 0.000 description 1
- 239000004312 hexamethylene tetramine Substances 0.000 description 1
- 150000002430 hydrocarbons Chemical group 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 description 1
- 229940071264 lithium citrate Drugs 0.000 description 1
- WJSIUCDMWSDDCE-UHFFFAOYSA-K lithium citrate (anhydrous) Chemical compound [Li+].[Li+].[Li+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O WJSIUCDMWSDDCE-UHFFFAOYSA-K 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- ZIUHHBKFKCYYJD-UHFFFAOYSA-N n,n'-methylenebisacrylamide Chemical compound C=CC(=O)NCNC(=O)C=C ZIUHHBKFKCYYJD-UHFFFAOYSA-N 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 230000005501 phase interface Effects 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 150000003377 silicon compounds Chemical class 0.000 description 1
- 239000002409 silicon-based active material Substances 0.000 description 1
- 239000011871 silicon-based negative electrode active material Substances 0.000 description 1
- 239000002109 single walled nanotube Substances 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 229960003080 taurine Drugs 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
-
- 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
-
- 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
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
-
- 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
-
- 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
- H01M4/134—Electrodes based on metals, Si or alloys
-
- 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
- H01M4/623—Binders being polymers fluorinated polymers
-
- 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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a negative electrode binder, a battery negative electrode comprising the negative electrode binder, a lithium ion battery core and a lithium ion battery, wherein the negative electrode binder comprises PR-PAA and carboxymethyl cellulose, the mass ratio of the PR-PAA to the carboxymethyl cellulose is (1-3) (1-2), and the PR-PAA and the carboxymethyl cellulose with specific mass ratio are selected to be matched to serve as the negative electrode binder, so that the binding capacity of the carboxymethyl cellulose and the sliding elasticity of the PR-PAA can be fully exerted, the obtained negative electrode binder has more excellent binding performance and binding effect on a silicon-based material, further the volume expansion of the silicon-based material can be better inhibited, and the cycle performance and stability of the lithium ion battery prepared by adopting the negative electrode binder are obviously improved.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a negative electrode binder, a battery negative electrode containing the negative electrode binder, a lithium ion battery core and a lithium ion battery.
Background
At present, a commercial lithium ion battery mainly uses graphite carbon-based negative electrode materials, but the theoretical specific capacity value is only 372mAh/g, and the requirement of an electric automobile on a battery with high specific capacity can not be met far. Among the numerous non-carbon based negative electrode candidate materials, silicon has received great attention in the field of batteries at its highest theoretical specific capacity value (4200 mAh/g). Although the theoretical lithium storage capacity of silicon is 11 times that of graphite, in the actual charge and discharge process, each silicon atom is combined with 4.4 lithium atoms on average, so that the volume change of a silicon anode reaches more than 300%, and the mechanical force generated by the severe volume shrinkage and expansion can lead the active material silicon to fall off from a current collector to lose electrical contact, and lead to mechanical pulverization of the silicon, and finally lead to rapid reduction of specific capacity value.
Therefore, the silicon-based negative electrode material is required to be adhered to the current collector by adopting an adhesive so as to stabilize the electrode plate structure and buffer the expansion/contraction of the electrode plate in the charge and discharge process, the adhesive of the silicon-based material is one of key factors influencing the first charge and discharge efficiency and the subsequent cycle stability of the electrode, and the adhesive with weak adhesive force cannot keep the electric contact activity between the silicon active materials, so that the first effect of the electrode is lower and the subsequent specific capacity is attenuated, and the realization of the performance of the high-energy-density battery is influenced.
Currently, the most widely used electrode binders are mainly PVDF, PAA, CMC and SBR. CN106058259a discloses a high specific capacity silicon-based negative electrode composite binder and a preparation method of a negative electrode sheet containing the binder, wherein the high specific capacity silicon-based negative electrode composite binder comprises 5-50wt% of sodium carboxymethyl cellulose, 5-30wt% of polyacrylic acid and 20-90wt% of styrene-butadiene rubber; the preparation method of the negative plate comprises the steps of glue preparation, conductive agent addition, main material addition, sieving, coating, high-temperature polymerization treatment, rolling and plate punching. The composite binder can solve the technical problem of short battery cycle life caused by huge volume change in the process of lithium ion intercalation and deintercalation of the existing silicon-based anode material.
CN111430712a discloses a preparation method of a novel silicon-based negative electrode binder of a lithium ion battery, which comprises the steps of mixing an acrylic acid monomer, a crosslinking agent and an initiator, and preparing crosslinked PAA by crosslinking polymerization under the condition of thermal initiation; and adding a grafting modifier into the crosslinked PAA, stirring and heating. The cross-linking agent is one or more of N, N-methylene bisacrylamide, polyethylene glycol or hexamethylenetetramine; the initiator is one or more of potassium persulfate, ammonium persulfate or sodium persulfate; the grafting modifier is one or more of lithium taurine, lithium acetate, lithium tartrate and lithium citrate, and the preparation method and the preparation process are simple, and the grafting crosslinking PAA adhesive with a crosslinking reticular multi-branched structure is produced by a crosslinking polymerization and grafting copolymerization method, so that the cost is low, and the large-scale production can be realized.
However, the binder provided in the prior art still has some drawbacks when applied to silicon-based materials, such as that PVDF is easy to swell when reacted with propylene carbonate in electrolyte, resulting in deformation of electrode structure and reduced binding power, thus resulting in faster capacity fade during battery cycling; while carboxyl groups (-COOH) in CMC and hydrocarbon groups (-OH) on the surface of the silicon compound can generate dehydration reaction to form stronger covalent connection and strengthen the structural integrity of the electrode, the CMC has high rigidity and low elongation at break (5-8 percent) and can not completely eliminate stress, so cracks are often generated in the repeated cycle process, and the capacity of the battery is obviously attenuated; the SBR has certain elasticity, but has weaker bonding capability, and carbon-carbon double bond degradation can occur in the charge and discharge process of the battery, so that the binder is invalid; PAA adhesive property is still acceptable, but the requirement of inhibiting the high volume expansion of the silicon negative electrode can be met by higher addition amount, and the improvement of energy density is not facilitated.
Therefore, in order to solve the above-mentioned problems, it is necessary to develop a negative electrode binder having excellent binding performance and excellent binding effect, and to achieve effective suppression of the volume expansion of a silicon-based material.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a negative electrode binder, a battery negative electrode, a lithium ion battery core and a lithium ion battery containing the negative electrode binder, wherein the negative electrode binder comprises PR-PAA and carboxymethyl cellulose with the mass ratio of (1-3) (1-2), and the two substances are matched under the specific mass ratio, so that the obtained negative electrode binder has more excellent binding performance and binding effect on a silicon-based material, further the volume expansion of the silicon-based material can be effectively inhibited, and the cycle performance and stability of the lithium ion battery prepared by adopting the negative electrode material are obviously improved.
To achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a negative electrode binder comprising PR-PAA and carboxymethyl cellulose;
and the mass ratio of PR-PAA to carboxymethyl cellulose is (1-3): (1-2), such as 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 1.2:2, 1.4:2, 1.6:2, 1.8:2, 2:2, 2.2:2, 2.4:2, 2.6:2, 2.8:2 or 3:2, etc.
The negative electrode binder provided by the invention comprises a combination of PR-PAA and carboxymethyl cellulose (CMC); PR is a supermolecule system consisting of a cyclic host molecule and a linear guest molecule penetrating through the inner cavity of the cyclic host molecule, and two ends of a chain organic substance are provided with end-capping groups for preventing the host ring from sliding down, and the ring in PR is connected with the linear PAA through covalent bonds to form PR-PAA crosslinking molecules; the ring in PR can freely move along with the volume change of the silicon particles, so that the sliding of the ring can effectively keep the particle shape of the silicon, so that the silicon particles cannot disintegrate in the continuous volume change process, and the PR has high elasticity, even if the crushed silicon particles can be bound up and then kept in a coalesced state, so that the negative electrode binder always has excellent binding performance on the silicon-based material; meanwhile, CMC is added in a matching way, carboxymethyl in the CMC can be connected with silicon particles through covalent bonds or hydrogen bonds, the connection force is strong, the shape of the silicon particles can be further kept from being damaged, and the CMC can form a coating similar to a solid electrolyte phase interface film (SEI) on the surface of the silicon particles, so that the decomposition of electrolyte can be effectively inhibited, and the cycle performance of a lithium ion battery is improved.
Furthermore, the negative electrode binder provided by the invention adopts PR-PAA and CMC to match, and the mass ratio of the PR-PAA to CMC is limited to be (1-3) (1-2), so that the obtained negative electrode binder not only can fully exert the covalent bond bonding capability of CMC, but also can exert the sliding elasticity of PR-PAA, has more excellent bonding performance and binding effect than a single component on a silicon-based material, further can effectively inhibit the volume expansion of the silicon-based material, and obviously improves the cycle performance and stability of a lithium ion battery adopting the negative electrode binder; if the amount of PR-PAA is relatively large, this will result in excessive costs, on the other hand, if the amount of PR-PAA is small, this will result in insufficient expansion binding ability of the resulting negative electrode binder to the silicon-based material.
Preferably, the PR-PAA is prepared from a material comprising polyrotaxane.
Preferably, the polyrotaxane comprises any one or a combination of at least two of linear polyrotaxane, side chain polyrotaxane or star polyrotaxane.
Preferably, the linear polyrotaxane comprises PEG-based linear segmented polyrotaxane and/or PMMA-based linear polyrotaxane.
Preferably, the polyrotaxane comprises a block copolymer polyrotaxane and/or a metal polyrotaxane.
Preferably, the number average molecular weight of the polyrotaxane is 5000 to 200000g/mol, for example 7000g/mol, 9000g/mol, 10000g/mol, 30000g/mol, 50000g/mol, 70000g/mol, 90000g/mol, or the like.
Preferably, styrene Butadiene Rubber (SBR) and/or polyvinylidene fluoride (PVDF) are further included in the negative electrode binder.
As the preferable technical scheme of the invention, the SBR is added in the negative electrode binder in a matching way, so that the flexibility of the negative electrode binder can be improved, and the cycle performance of the lithium ion battery is further improved, and the PVDF is beneficial to enhancing the wettability of the pole piece and is also beneficial to improving the cycle performance of the lithium ion battery.
Preferably, the mass ratio of PR-PAA to styrene butadiene rubber is (1-3) (0.5-1), such as 2:0.55, 2:0.6, 2:0.65, 2:0.7, 2:0.75, 2:0.8, 2:0.85, 2:0.9 or 2:0.95, etc.
Preferably, the mass ratio of PR-PAA to polyvinylidene fluoride is (1-3): (0.5-1), such as 2:0.55, 2:0.6, 2:0.65, 2:0.7, 2:0.75, 2:0.8, 2:0.85, 2:0.9 or 2:0.95, etc.
In a second aspect, the present invention provides a battery anode comprising a current collector and an anode material coated on the surface of the current collector;
the anode material includes an anode active material, a conductive agent, and the anode binder according to the first aspect.
Preferably, the mass ratio of the negative electrode active material, the conductive agent and the negative electrode binder is (94-97): 1-2.1): 2.5-6.
Wherein, the mass ratio of the negative electrode active material to the negative electrode binder can be 95:3, 95:3.5, 95:4, 95:4.5, 95:5 or 95:5.5, etc.
The mass ratio of the conductive agent to the negative electrode binder is 1.5:3, 1.5:3.5, 1.5:4, 1.5:4.5, 1.5:5 or 1.5:5.5, etc.
Preferably, the negative electrode active material includes a silicon-based negative electrode active material.
Preferably, the silicon-based anode active material comprises any one or a combination of at least two of micro silicon, nano silicon, silicon oxygen composite material or silicon carbon composite material.
Preferably, the conductive agent includes any one or a combination of at least two of conductive carbon black, carbon fiber, graphene or carbon nanotube.
In a third aspect, the present invention provides a lithium ion cell comprising a positive electrode, a battery negative electrode as described in the second aspect, and a separator.
In a fourth aspect, the present invention provides a lithium ion battery comprising a casing, an electrolyte and a lithium ion battery core according to the third aspect;
the lithium ion cell and electrolyte are sealed within the battery housing.
In a fifth aspect, the present invention provides a use of a lithium ion battery according to the fourth aspect in an electric vehicle.
Compared with the prior art, the invention has the following beneficial effects:
the negative electrode binder provided by the invention comprises a combination of PR-PAA and carboxymethyl cellulose, wherein the mass ratio of the PR-PAA to the carboxymethyl cellulose is (1-3): (1-2), and the PR-PAA and the carboxymethyl cellulose with specific mass ratios are selected to be matched as the negative electrode binder, so that the covalent bond bonding capability of CMC can be fully exerted, the sliding elasticity of the PR-PAA can be effectively exerted, and the negative electrode binder has more excellent bonding performance and binding effect on silicon-based materials than the CMC alone or the PR-PAA alone.
Detailed Description
The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
Example 1
A negative electrode binder consists of PR-PAA, CMC and SBR with the mass ratio of 2:1.5:0.75.
Example 2
A negative electrode binder consists of PR-PAA, CMC and SBR in a mass ratio of 1:1:0.5.
Example 3
A negative electrode binder consists of PR-PAA, CMC and SBR in a mass ratio of 3:1:0.5.
Example 4
A negative electrode binder consists of PR-PAA, CMC and SBR with the mass ratio of 0.5:1.5:0.75.
Example 5
A negative electrode binder consists of PR-PAA and CMC in a mass ratio of 2:1.5.
Comparative example 1
A negative electrode binder consists of CMC and SBR with a mass ratio of 1.5:0.75.
Comparative example 2
A negative electrode binder consists of PR-PAA and SBR in a mass ratio of 2:0.75.
Comparative example 3
A negative electrode binder consisting of PR-PAA.
Comparative example 4
A negative electrode binder consisting of CMC.
Application example 1
A lithium ion battery comprises a shell, electrolyte and a lithium ion battery core;
wherein, the shell is an aluminum plastic film;
the electrolyte comprises a solute and a solvent, wherein the solvent is EC and DMC with the mass ratio of 4:1, and the solute is LiPF 6 ；
The lithium ion battery cell comprises a positive electrode (an active substance is NCM 811), a battery negative electrode (composed of a silicon oxygen negative electrode, SP, single-walled carbon nanotubes and a negative electrode binder (preparation example 1) in a mass ratio of 95:1:0.05:3.95) and a separator (a 12+4 ceramic coated separator);
the preparation process of the lithium ion battery provided by the application example comprises the following steps:
(1) Stirring, coating, rolling and die cutting the anode material and the cathode material respectively to obtain an anode plate and a cathode plate respectively;
(2) And (3) laminating, spot welding, packaging and baking the positive plate, the negative plate and the diaphragm obtained in the step (1), and sequentially injecting, standing, forming, aging and capacity-dividing after electrolyte is injected to obtain the lithium ion battery.
Application example 2
A lithium ion battery was different from application example 1 only in that the negative electrode binder obtained in example 2 was used instead of the negative electrode binder obtained in example 1, and other components, amounts and preparation methods were the same as those of application example 1.
Application example 3
A lithium ion battery was different from application example 1 only in that the negative electrode binder obtained in example 3 was used instead of the negative electrode binder obtained in example 1, and other components, amounts and preparation methods were the same as those of application example 1.
Application example 4
A lithium ion battery was different from application example 1 only in that the negative electrode binder obtained in example 4 was used instead of the negative electrode binder obtained in example 1, and other components, amounts and preparation methods were the same as those of application example 1.
Application example 5
A lithium ion battery was different from application example 1 only in that the negative electrode binder obtained in example 5 was used instead of the negative electrode binder obtained in example 1, and other components, amounts and preparation methods were the same as those of application example 1.
Comparative application example 1
A lithium ion battery was different from application example 1 only in that the negative electrode binder obtained in comparative example 1 was used instead of the negative electrode binder obtained in example 1, and the other components, amounts and preparation methods were the same as those of application example 1.
Comparative application example 2
A lithium ion battery was different from application example 1 only in that the negative electrode binder obtained in comparative example 2 was used instead of the negative electrode binder obtained in example 1, and the other components, amounts and preparation methods were the same as those of application example 1.
Comparative application example 3
A lithium ion battery was different from application example 1 only in that the negative electrode binder obtained in comparative example 3 was used instead of the negative electrode binder obtained in example 1, and the other components, amounts and preparation methods were the same as those of application example 1.
Comparative application example 4
A lithium ion battery was different from application example 1 only in that the negative electrode binder obtained in comparative example 4 was used instead of the negative electrode binder obtained in example 1, and the other components, amounts and preparation methods were the same as those of application example 1.
Performance test:
(1) Cycle performance: the capacity retention rate of the obtained lithium ion battery was measured by cycling the lithium ion battery at 1C/1C for 500 weeks at a voltage of 2.75-4.2V.
The lithium ion batteries provided in application examples 1 to 5 and comparative application examples 1 to 4 were tested according to the above test scheme, and the test results are shown in table 1:
TABLE 1
From the data in table 1, it can be seen that:
the cycle capacity retention rate of the lithium ion batteries obtained in application examples 1 to 5 is 77.6 to 83.2%;
as can be seen from comparing the data of application example 1 and comparative application examples 1 to 4, the cycle capacity retention rate of the lithium ion battery prepared without adding the negative electrode binder of PR-PAA and the lithium ion battery prepared without adding the negative electrode binder of CMC are both greatly reduced;
as can be seen from comparing the data of application example 1 and application example 4, the use amount of PR-PAA is relatively low, which also affects the cycle performance of the finally obtained lithium ion battery;
finally, it can be seen from the data of application examples 1 and 5 that the cycle performance of the lithium ion battery finally obtained without adding SBR as a negative electrode binder is also reduced.
The applicant states that the present invention is described by way of the above examples as a negative electrode binder and a battery negative electrode, a lithium ion cell and a lithium ion battery comprising the same, but the present invention is not limited to the above examples, i.e. it is not meant that the present invention must be practiced in dependence on the above examples. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of raw materials for the product of the present invention, addition of auxiliary components, selection of specific modes, etc., falls within the scope of the present invention and the scope of disclosure.
Claims (10)
1. A negative electrode binder, characterized in that the negative electrode binder comprises PR-PAA and carboxymethyl cellulose;
the mass ratio of PR-PAA to carboxymethyl cellulose is (1-3) (1-2).
2. The negative electrode binder of claim 1, wherein the PR-PAA is prepared from a starting material comprising polyrotaxane;
preferably, the polyrotaxane comprises any one or a combination of at least two of linear polyrotaxane, side chain polyrotaxane and star polyrotaxane;
preferably, the linear polyrotaxane comprises PEG-based linear segmented polyrotaxane and/or PMMA-based linear polyrotaxane;
preferably, the polyrotaxane comprises a block copolymer polyrotaxane and/or a metal polyrotaxane;
preferably, the number average molecular weight of the polyrotaxane is 5000 to 200000g/mol.
3. The negative electrode binder according to claim 1 or 2, further comprising styrene-butadiene rubber and/or polyvinylidene fluoride;
preferably, the mass ratio of PR-PAA to styrene-butadiene rubber is (1-3) (0.5-1);
preferably, the mass ratio of PR-PAA to polyvinylidene fluoride is (1-3): 0.5-1.
4. A battery negative electrode, which is characterized by comprising a current collector and a negative electrode material coated on the surface of the current collector;
the anode material comprising an anode active material, a conductive agent, and the anode binder according to any one of claims 1 to 3.
5. The battery anode according to claim 4, wherein the mass ratio of the anode active material, the conductive agent, and the anode binder is (94-97): 1-2.1): 2.5-6.
6. The battery anode according to claim 4 or 5, wherein the anode active material comprises a silicon-based anode active material;
preferably, the silicon-based anode active material comprises any one or a combination of at least two of micro silicon, nano silicon, silicon oxygen composite material or silicon carbon composite material.
7. The battery anode according to any one of claims 4 to 6, wherein the conductive agent comprises any one or a combination of at least two of conductive carbon black, carbon fiber, graphene, or carbon nanotube.
8. A lithium ion cell, characterized in that it comprises a positive electrode, a battery negative electrode according to any one of claims 4 to 7 and a separator.
9. A lithium ion battery, characterized in that the lithium ion battery comprises a shell, an electrolyte and the lithium ion battery cell according to claim 8;
the lithium ion battery cell and the electrolyte are sealed within the battery housing.
10. Use of the lithium ion battery of claim 9 in an electric vehicle.
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| CN202310578745.5A CN116404166A (en) | 2023-05-22 | 2023-05-22 | Negative electrode binder, battery negative electrode containing same, lithium ion battery core and lithium ion battery |
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| CN202310578745.5A CN116404166A (en) | 2023-05-22 | 2023-05-22 | Negative electrode binder, battery negative electrode containing same, lithium ion battery core and lithium ion battery |
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