CN113921895A - Lithium iron phosphate battery and preparation method thereof - Google Patents
Lithium iron phosphate battery and preparation method thereof Download PDFInfo
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- CN113921895A CN113921895A CN202111151638.1A CN202111151638A CN113921895A CN 113921895 A CN113921895 A CN 113921895A CN 202111151638 A CN202111151638 A CN 202111151638A CN 113921895 A CN113921895 A CN 113921895A
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- battery
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- iron phosphate
- negative electrode
- current collector
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- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 title claims description 74
- 238000002360 preparation method Methods 0.000 title description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 33
- 239000011889 copper foil Substances 0.000 claims abstract description 33
- 239000000853 adhesive Substances 0.000 claims abstract description 30
- 230000001070 adhesive effect Effects 0.000 claims abstract description 30
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000010439 graphite Substances 0.000 claims abstract description 20
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 20
- 229910021385 hard carbon Inorganic materials 0.000 claims abstract description 19
- 239000007773 negative electrode material Substances 0.000 claims abstract description 19
- 239000002131 composite material Substances 0.000 claims abstract description 16
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 16
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 14
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 claims abstract 2
- 239000000463 material Substances 0.000 claims description 51
- 238000003825 pressing Methods 0.000 claims description 32
- 239000011888 foil Substances 0.000 claims description 28
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 27
- 229910052782 aluminium Inorganic materials 0.000 claims description 27
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 24
- 239000011230 binding agent Substances 0.000 claims description 20
- 238000007646 gravure printing Methods 0.000 claims description 19
- 238000004804 winding Methods 0.000 claims description 14
- 239000002033 PVDF binder Substances 0.000 claims description 12
- 239000013543 active substance Substances 0.000 claims description 12
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 12
- 239000007767 bonding agent Substances 0.000 claims description 2
- 238000003475 lamination Methods 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 229910000398 iron phosphate Inorganic materials 0.000 claims 3
- 239000007774 positive electrode material Substances 0.000 abstract description 5
- 238000004132 cross linking Methods 0.000 abstract description 4
- 239000005955 Ferric phosphate Substances 0.000 abstract 1
- 229940032958 ferric phosphate Drugs 0.000 abstract 1
- 229910000399 iron(III) phosphate Inorganic materials 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 13
- 238000012360 testing method Methods 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 11
- 239000010405 anode material Substances 0.000 description 5
- 239000010406 cathode material Substances 0.000 description 4
- 238000009830 intercalation Methods 0.000 description 4
- 241000784732 Lycaena phlaeas Species 0.000 description 3
- 239000011229 interlayer Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 125000004122 cyclic group Chemical group 0.000 description 2
- 230000002687 intercalation Effects 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 238000011179 visual inspection Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000010410 dusting Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000007787 solid Substances 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
- 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
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
-
- 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
-
- 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
- H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
-
- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
-
- 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
- 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
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- 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
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/661—Metal or alloys, e.g. alloy coatings
-
- 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
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The invention discloses a lithium ion battery of ferric phosphate, belonging to the technical field of lithium ion batteries, wherein graphite and hard carbon are used as a composite negative electrode material, a negative current collector is a copper foil printed by a gravure, the positive and negative electrode materials and the current collector are in a cross-linking state, and two adhesives of SBR and L133 are combined for use to increase the bonding strength of the positive and negative electrode materials and the current collector.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium iron phosphate battery for raw material silver powder.
Background
A lithium ion battery is a secondary battery (rechargeable battery) that mainly operates by movement of lithium ions between a positive electrode and a negative electrode, during charging and discharging, Li+ Intercalation and deintercalation to and from two electrodes: upon charging, Li+From the positive poleDe-intercalation, and intercalating the electrolyte into a negative electrode which is in a lithium-rich state; the opposite is true during discharge.
The negative electrode plate used in the current market is mainly prepared from graphite, and the graphite has high gram capacity, low price and convenient production and processing, so the negative electrode plate is a conventional negative electrode material of the lithium ion battery. The hard carbon is used as a novel negative electrode material in recent years, compared with graphite, the gram capacity is lower, but because the interlayer spacing is larger than that of the graphite, lithium ions are easy to be deintercalated in the negative electrode material, and the negative electrode material cannot deform greatly to cause shedding.
In addition, the adhesive adopted by the lithium ion battery negative electrode also has a great influence on the efficiency of the battery, the adhesives used in the current market comprise two types, namely a water-based adhesive and an oil-based adhesive, wherein the water-based adhesive comprises SBR and L133 commonly, when the L133 is selected as the adhesive, when the energy density of the battery is pursued, the coating surface density of a pole piece is increased, the thickness of the pole piece is increased, the flexibility of the pole piece is reduced, the pole piece is brittle and easy to crack, and the electrical property of the battery is influenced; when SBR is selected as the adhesive, the cycle life of the prepared battery is not ideal, so that the two adhesives are combined for use, the advantages of the two adhesives can be effectively combined, the flexibility of the pole piece can be improved, the processing performance is facilitated, and the long-life characteristic of L133 can be kept.
The current collectors of lithium ion batteries are also key parts of lithium ion batteries, the current collectors used in the current market are aluminum foils and copper foils with different thicknesses and are solid foils, and the adoption of hollow reticular aluminum foils and reticular copper foils in the current collectors of the lithium ion batteries is not reported yet. The method is characterized in that the anode and cathode materials and the current collector are in a cross-linking state, so that the bonding strength of the anode and cathode materials and the current collector is increased, the conductivity is improved, and the internal resistance of the battery is reduced. In the prior art, a gravure printing process is mainly applied to an anode current collector aluminum foil in the preparation of a lithium iron phosphate battery, and mainly aims to solve the problem of low conductivity of a lithium iron phosphate anode material.
Disclosure of Invention
The invention aims to provide a lithium iron phosphate battery which uses graphite and hard carbon as a composite negative material, uses a negative current collector which is a gravure copper foil, enables the positive and negative materials and the current collector to be in a cross-linking state, and combines SBR and L133 adhesive to increase the bonding strength of the positive and negative materials and the current collector.
The invention provides a lithium iron phosphate battery which mainly comprises the following components:
the positive electrode of the lithium iron phosphate battery is made of 5% of conductive carbon black, 4% of binder PVDF and 91% of aluminum foil current collector, the thickness of the aluminum foil current collector is 16 microns, the active substance of the positive electrode of the battery is lithium iron phosphate, and the thickness of a pole piece of the positive electrode of the battery is 100-140 microns after cold pressing;
the material of the lithium iron phosphate battery negative electrode comprises a graphite and hard carbon composite material in an amount of 93%, conductive carbon black in an amount of 3%, CMC in an amount of 1.6%, a bonding agent prepared by mixing L133 and SBR in an amount of 2.4%, and a gravure printing copper foil current collector with the thickness of 8-10 microns, wherein the thickness of a pole piece of the battery negative electrode material after cold pressing is also 100-140 microns; the content of L133 in the adhesive accounts for 0-2.4% of the material of the battery cathode, and correspondingly, the content of SBR accounts for 2.4-0% of the material of the battery cathode;
the diaphragm of the lithium iron phosphate battery is a PP/PE/PP three-layer diaphragm with a winding or lamination structure, and the design capacity of the battery is 50-110 Ah.
Further, the copper foil current collector for gravure printing is a net-shaped copper foil.
Preferably, the thickness of the pole piece of the positive electrode material of the battery is 105um after cold pressing; the content of L133 in the adhesive accounts for 1.6% of the material of the battery negative electrode, correspondingly, the content of SBR accounts for 0.8% of the material of the battery negative electrode, the thickness of the copper foil current collector for gravure printing is 8um, and the thickness of a pole piece of the material of the battery negative electrode after cold pressing is 112 um; the diaphragm is of a winding structure, and the design capacity of the battery is 80 Ah.
The thickness of the pole piece of the battery anode is 120um after cold pressing; the content of L133 in the adhesive accounts for 0.4% of the material of the battery negative electrode, correspondingly, the content of SBR accounts for 2.0% of the material of the battery negative electrode, the thickness of the copper foil current collector for gravure printing is 10um, and the thickness of a pole piece of the material of the battery negative electrode is 115um after cold pressing; the diaphragm is of a laminated structure, and the design capacity of the battery is 100 Ah.
More preferably, the ratio of the content of L133 to the content of SBR in the binder is 1: 1.
Compared with the prior art, the lithium iron phosphate battery provided by the invention has the following advantages:
1. according to the lithium iron phosphate battery provided by the invention, the anode and cathode materials and the current collector are in a cross-linking state, so that the bonding strength of the anode and cathode materials and the current collector is increased, the conductivity is improved, and the internal resistance of the battery is reduced.
2. According to the lithium iron phosphate battery provided by the invention, the SBR and the L133 are combined for use, so that the advantages of the SBR and the L133 can be effectively combined, the flexibility of a pole piece can be improved, the processing performance is facilitated, and the long-life characteristic of the L133 can be maintained.
3. According to the lithium iron phosphate battery provided by the invention, graphite and hard carbon are used as a composite negative electrode material, the negative electrode current collector is a copper foil printed by a gravure, so that the adhesion strength of a membrane and the copper foil is enhanced, and the lithium ions are easier to de-embed in the negative electrode by combining a larger interlayer distance between the hard carbon, so that the cycle life of the battery is prolonged.
Detailed Description
The technical solutions for achieving the objects of the present invention are further illustrated by the following specific examples, and it should be noted that the technical solutions claimed in the present invention include, but are not limited to, the following examples.
Example 1
As a first specific embodiment of the present invention, the lithium iron phosphate battery provided in this example mainly includes the following components:
the positive material of the lithium iron phosphate battery comprises 5% of conductive carbon black, 4% of binder PVDF and 91% of aluminum foil current collector, the thickness of the aluminum foil current collector is 16um, the active substance of the positive electrode of the battery is lithium iron phosphate, and the thickness of the positive electrode of the battery is 120um after cold pressing.
The material of the lithium iron phosphate battery negative electrode comprises 93% of graphite and hard carbon composite material, 3% of conductive carbon black, 1.6% of CMC, 1.2% of L133 adhesive, 1.2% of SBR adhesive and a gravure printing copper foil current collector with the thickness of 8um, and the thickness of a pole piece of the battery negative electrode material is also 115um after cold pressing.
The diaphragm of the lithium iron phosphate battery is a PP/PE/PP three-layer diaphragm adopting a winding structure, and the design capacity of the battery is 100 Ah.
Example 2
As a second specific embodiment of the present invention, the lithium iron phosphate battery provided in this example mainly includes the following components:
the positive material of the lithium iron phosphate battery comprises 5% of conductive carbon black, 4% of binder PVDF and 91% of aluminum foil current collector, the thickness of the aluminum foil current collector is 16um, the active substance of the positive electrode of the battery is lithium iron phosphate, and the thickness of the positive electrode of the battery is 120um after cold pressing.
The material of the lithium iron phosphate battery negative electrode comprises 93% of graphite and hard carbon composite material, 3% of conductive carbon black, 1.6% of CMC, 0.4% of L133 adhesive, 2.0% of SBR adhesive and a gravure printing copper foil current collector with the thickness of 8um, and the thickness of a pole piece of the battery negative electrode material is also 115um after cold pressing.
The diaphragm of the lithium iron phosphate battery is a PP/PE/PP three-layer diaphragm adopting a winding structure, and the design capacity of the battery is 100 Ah.
Example 3
As a third specific embodiment of the present invention, the lithium iron phosphate battery provided in this example mainly includes the following components:
the positive material of the lithium iron phosphate battery comprises 5% of conductive carbon black, 4% of binder PVDF and 91% of aluminum foil current collector, the thickness of the aluminum foil current collector is 16um, the active substance of the positive electrode of the battery is lithium iron phosphate, and the thickness of the positive electrode of the battery is 120um after cold pressing.
The material of the lithium iron phosphate battery negative electrode comprises 93% of graphite and hard carbon composite material, 3% of conductive carbon black, 1.6% of CMC, 2.0% of L133 adhesive, 0.4% of SBR adhesive and a gravure printing copper foil current collector with the thickness of 8um, and the thickness of a pole piece of the battery negative electrode material is also 115um after cold pressing.
The diaphragm of the lithium iron phosphate battery is a PP/PE/PP three-layer diaphragm adopting a winding structure, and the design capacity of the battery is 100 Ah.
Example 4
As a first specific embodiment of the present invention, the lithium iron phosphate battery provided in this example mainly includes the following components:
the positive material of the lithium iron phosphate battery comprises 5% of conductive carbon black, 4% of binder PVDF and 91% of aluminum foil current collector, the thickness of the aluminum foil current collector is 16um, the active substance of the positive electrode of the battery is lithium iron phosphate, and the thickness of the positive electrode of the battery is 120um after cold pressing.
The material of the lithium iron phosphate battery negative electrode comprises 93% of graphite and hard carbon composite material, 3% of conductive carbon black, 1.6% of CMC, 1.2% of L133 adhesive, 1.2% of SBR adhesive and a gravure printing copper foil current collector with the thickness of 8um, and the thickness of a pole piece of the battery negative electrode material is also 115um after cold pressing.
The diaphragm of the lithium iron phosphate battery is a PP/PE/PP three-layer diaphragm adopting a winding structure, and the design capacity of the battery is 100 Ah.
Comparative example 1
As a comparison with the technical solutions of the foregoing embodiments 1 to 4, the lithium iron phosphate battery provided in comparative example 1 mainly includes the following components:
the material of the lithium iron phosphate battery anode is the same as the scheme, and comprises 5% of conductive carbon black, 4% of binder PVDF and 91% of aluminum foil current collector, wherein the thickness of the aluminum foil current collector is 16um, the active substance of the battery anode is lithium iron phosphate, and the thickness of the pole piece of the material of the battery anode is 120um after cold pressing.
The material of the lithium iron phosphate battery negative electrode comprises 93% of graphite and hard carbon composite material, 3% of conductive carbon black, 2.4% of L133 adhesive and a gravure printing copper foil current collector with the thickness of 8um, and the thickness of a pole piece of the material of the battery negative electrode is also 115um after cold pressing.
The diaphragm of the lithium iron phosphate battery is a PP/PE/PP three-layer diaphragm adopting a winding structure, and the design capacity of the battery is 100 Ah.
Comparative example 2
As a further comparison with the technical solutions of the foregoing embodiments 1 to 4, the lithium iron phosphate battery provided in comparative example 2 mainly comprises the following components:
the material of the lithium iron phosphate battery anode is the same as the scheme, and comprises 5% of conductive carbon black, 4% of binder PVDF and 91% of aluminum foil current collector, wherein the thickness of the aluminum foil current collector is 16um, the active substance of the battery anode is lithium iron phosphate, and the thickness of the pole piece of the material of the battery anode is 120um after cold pressing.
The material of the lithium iron phosphate battery negative electrode comprises 93% of graphite and hard carbon composite material, 3% of conductive carbon black, 2.4% of SBR adhesive and a gravure printing copper foil current collector with the thickness of 8um, and the thickness of a pole piece of the material of the battery negative electrode is also 115um after cold pressing.
The diaphragm of the lithium iron phosphate battery is a PP/PE/PP three-layer diaphragm adopting a winding structure, and the design capacity of the battery is 100 Ah.
That is, in the technical solutions of the above embodiments 1 to 4 and the technical solutions of the comparative examples 1 and 2, the material and the specification of the positive electrode of the lithium iron phosphate battery are kept unchanged, and the selection and the proportion of the binder in the material of the negative electrode of the battery are mainly adjusted.
The test method is as follows:
1. visual inspection is carried out on three layers in the negative electrode slice of the wound battery core to determine whether the powder falling phenomenon exists;
2. and (3) cyclic charge and discharge performance testing, namely performing charge and discharge testing on the prepared battery at a current of 1C until the capacity reaches 80% of the rated capacity, and performing charge and discharge testing on the prepared battery until the capacity reaches 80% of the rated capacity.
The test results can be referred to the following Table 1
As can be seen from the test result data in table 1, the battery prepared by using the L133 binder and the SBR binder in combination under the condition of no change of other conditions has significantly improved cell dusting condition and better charge and discharge cycle times.
Example 5
As a fifth specific embodiment of the present invention, the lithium iron phosphate battery provided in this example mainly includes:
the positive material of the lithium iron phosphate battery comprises 5% of conductive carbon black, 4% of binder PVDF and 91% of aluminum foil current collector, the thickness of the aluminum foil current collector is 16um, the active substance of the positive electrode of the battery is lithium iron phosphate, and the thickness of the positive electrode of the battery is 120um after cold pressing.
The material of the lithium iron phosphate battery negative electrode comprises 93% of graphite and hard carbon composite material, 3% of conductive carbon black, 1.6% of CMC, 2.4% of SBR binder and a gravure printing reticular copper foil current collector with the thickness of 10um, and the thickness of a pole piece of the battery negative electrode material is 115um after cold pressing.
The diaphragm of the lithium iron phosphate battery is a PP/PE/PP three-layer diaphragm adopting a winding structure, and the design capacity of the battery is 80 Ah.
Example 6
As a sixth specific embodiment of the present invention, the lithium iron phosphate battery provided in this example mainly includes the following components:
the positive material of the lithium iron phosphate battery comprises 5% of conductive carbon black, 4% of binder PVDF and 91% of aluminum foil current collector, the thickness of the aluminum foil current collector is 16um, the active substance of the positive electrode of the battery is lithium iron phosphate, and the thickness of the positive electrode of the battery is 120um after cold pressing.
The material of the lithium iron phosphate battery negative electrode comprises 93% of graphite and hard carbon composite material, 3% of conductive carbon black, 1.6% of CMC, 2.4% of SBR binder and a gravure printing reticular copper foil current collector with the thickness of 8um, and the thickness of a pole piece of the battery negative electrode material is 115um after cold pressing.
The diaphragm of the lithium iron phosphate battery is a PP/PE/PP three-layer diaphragm adopting a winding structure, and the design capacity of the battery is 80 Ah.
Comparative example 3
As a comparison with the technical solutions of the foregoing examples 5 and 6, comparative example 3 provides a lithium iron phosphate battery, which mainly comprises the following components:
the positive material of the lithium iron phosphate battery comprises 5% of conductive carbon black, 4% of binder PVDF and 91% of aluminum foil current collector, the thickness of the aluminum foil current collector is 16um, the active substance of the positive electrode of the battery is lithium iron phosphate, and the thickness of the positive electrode of the battery is 120um after cold pressing.
The material of the lithium iron phosphate battery negative electrode comprises 93% of graphite and hard carbon composite material, 3% of conductive carbon black, 1.6% of CMC, 2.4% of SBR binder and a common copper foil current collector with the thickness of 10um, and the thickness of a pole piece of the material of the battery negative electrode is also 115um after cold pressing.
The diaphragm of the lithium iron phosphate battery is a PP/PE/PP three-layer diaphragm adopting a winding structure, and the design capacity of the battery is 80 Ah.
Comparative example 4
As a comparison with the technical solutions of the foregoing examples 5 and 6, comparative example 4 provides a lithium iron phosphate battery, which mainly comprises the following components:
the positive material of the lithium iron phosphate battery comprises 5% of conductive carbon black, 4% of binder PVDF and 91% of aluminum foil current collector, the thickness of the aluminum foil current collector is 16um, the active substance of the positive electrode of the battery is lithium iron phosphate, and the thickness of the positive electrode of the battery is 120um after cold pressing.
The material of the lithium iron phosphate battery negative electrode comprises 93% of graphite and hard carbon composite material, 3% of conductive carbon black, 1.6% of CMC, 2.4% of SBR binder and a common copper foil current collector with the thickness of 8um, and the thickness of a pole piece of the material of the battery negative electrode is also 115um after cold pressing.
The diaphragm of the lithium iron phosphate battery is a PP/PE/PP three-layer diaphragm adopting a winding structure, and the design capacity of the battery is 80 Ah.
That is, in the technical solutions of the above embodiments 5 and 6, and in the technical solutions of the comparative examples 3 and 4, we keep the material and the specification of the positive electrode of the lithium iron phosphate battery unchanged, mainly adjust the selection of the copper foil current collector in the material of the negative electrode of the battery, compare the gravure-printed mesh copper foil current collector with the common copper foil current collector, and through comparison tests, it can be clearly seen from the test data that the advantages brought by the gravure-printed mesh copper foil current collector in the technical solutions are obtained.
The test method is as follows:
1. visual inspection is carried out on three layers in the negative electrode slice of the wound battery core to determine whether the powder falling phenomenon exists;
2. and (3) cyclic charge and discharge performance testing, namely performing charge and discharge testing on the prepared battery at a current of 1C until the capacity reaches 80% of the rated capacity, and performing charge and discharge testing on the prepared battery until the capacity reaches 80% of the rated capacity.
The test results can be referred to the following Table 2
As can be seen from the test result data in table 2, the battery prepared by gravure-printing the mesh copper foil current collector has significantly lower internal resistance of the battery core and better charge-discharge cycle times under the condition of no change of other conditions.
To sum up, from the test data results of the embodiments 1 to 6 and the comparative examples 1 to 4, the lithium iron phosphate battery prepared by the technical scheme of the present invention has the positive and negative electrode materials and the current collector in a cross-linked state, increases the bonding strength between the positive and negative electrode materials and the current collector, improves the electrical conductivity, reduces the internal resistance of the battery, and combines the SBR and the L133 two adhesives for use, so that the advantages of the two adhesives can be effectively combined, the flexibility of the pole piece can be improved, the processability can be improved, the long life characteristic of the L133 can be maintained, meanwhile, the graphite and the hard carbon are used as the composite negative electrode material, the negative electrode current collector is the gravure printing copper foil to enhance the adhesion strength between the membrane and the copper foil, and the large interlayer spacing between the hard carbon is combined, so that the lithium ion intercalation process at the negative electrode is easier, and the cycle life of the battery is prolonged.
Claims (5)
1. A lithium ion iron phosphate battery is characterized in that:
the positive electrode of the lithium iron phosphate battery is made of 5% of conductive carbon black, 4% of binder PVDF and 91% of aluminum foil current collector, the thickness of the aluminum foil current collector is 16 microns, the active substance of the positive electrode of the battery is lithium iron phosphate, and the thickness of a pole piece of the positive electrode of the battery is 100-140 microns after cold pressing;
the material of the lithium iron phosphate battery negative electrode comprises a graphite and hard carbon composite material in an amount of 93%, conductive carbon black in an amount of 3%, CMC in an amount of 1.6%, a bonding agent prepared by mixing L133 and SBR in an amount of 2.4%, and a gravure printing copper foil current collector with the thickness of 8-10 microns, wherein the thickness of a pole piece of the battery negative electrode material after cold pressing is also 100-140 microns; the content of L133 in the adhesive accounts for 0-2.4% of the material of the battery cathode, and correspondingly, the content of SBR accounts for 2.4-0% of the material of the battery cathode;
the diaphragm of the lithium iron phosphate battery is a PP/PE/PP three-layer diaphragm with a winding or lamination structure, and the design capacity of the battery is 50-100 Ah.
2. The lithium iron phosphate battery of claim 1, wherein: further, the copper foil current collector for gravure printing is a net-shaped copper foil.
3. The lithium-ion-iron-phosphate battery of claim 1 or 2, wherein: the thickness of the pole piece of the battery anode is 105um after cold pressing; the content of L133 in the adhesive accounts for 1.6% of the material of the battery negative electrode, correspondingly, the content of SBR accounts for 0.8% of the material of the battery negative electrode, the thickness of the copper foil current collector for gravure printing is 8um, and the thickness of a pole piece of the material of the battery negative electrode after cold pressing is 112 um; the diaphragm is of a winding structure, and the design capacity of the battery is 80 Ah.
4. The lithium-ion-iron-phosphate battery of claim 1 or 2, wherein: the thickness of the pole piece of the battery anode is 120um after cold pressing; the content of L133 in the adhesive accounts for 0.4% of the material of the battery negative electrode, correspondingly, the content of SBR accounts for 2.0% of the material of the battery negative electrode, the thickness of the copper foil current collector for gravure printing is 10um, and the thickness of a pole piece of the material of the battery negative electrode is 115um after cold pressing; the diaphragm is of a laminated structure, and the design capacity of the battery is 100 Ah.
5. The lithium iron phosphate battery of claim 1, wherein: the ratio of the content of L133 to the content of SBR in the adhesive is 1: 1.
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