CN115224267A - Positive plate, secondary battery and power utilization device - Google Patents
Positive plate, secondary battery and power utilization device Download PDFInfo
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- CN115224267A CN115224267A CN202210878476.XA CN202210878476A CN115224267A CN 115224267 A CN115224267 A CN 115224267A CN 202210878476 A CN202210878476 A CN 202210878476A CN 115224267 A CN115224267 A CN 115224267A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 34
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 31
- 239000007774 positive electrode material Substances 0.000 claims abstract description 30
- 238000000576 coating method Methods 0.000 claims abstract description 23
- 239000011248 coating agent Substances 0.000 claims abstract description 19
- 239000011230 binding agent Substances 0.000 claims abstract description 11
- 239000011247 coating layer Substances 0.000 claims abstract description 8
- 239000003792 electrolyte Substances 0.000 claims description 16
- 239000002904 solvent Substances 0.000 claims description 6
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 5
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 5
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- 239000011149 active material Substances 0.000 claims description 4
- 229910003002 lithium salt Inorganic materials 0.000 claims description 4
- 159000000002 lithium salts Chemical class 0.000 claims description 4
- 238000000926 separation method Methods 0.000 claims description 4
- 238000004806 packaging method and process Methods 0.000 claims description 2
- 239000013543 active substance Substances 0.000 abstract description 9
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 22
- 229910001416 lithium ion Inorganic materials 0.000 description 22
- 238000005056 compaction Methods 0.000 description 17
- 239000002245 particle Substances 0.000 description 14
- 238000003825 pressing Methods 0.000 description 13
- 238000000034 method Methods 0.000 description 12
- 230000008569 process Effects 0.000 description 11
- 238000012360 testing method Methods 0.000 description 11
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 9
- 229910052744 lithium Inorganic materials 0.000 description 9
- 230000004888 barrier function Effects 0.000 description 7
- 238000001556 precipitation Methods 0.000 description 7
- 239000006258 conductive agent Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 239000007773 negative electrode material Substances 0.000 description 5
- -1 negative pole piece Substances 0.000 description 5
- 239000002002 slurry Substances 0.000 description 5
- 239000000853 adhesive Substances 0.000 description 4
- 230000001070 adhesive effect Effects 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 238000012546 transfer Methods 0.000 description 4
- 239000002033 PVDF binder Substances 0.000 description 3
- 239000004743 Polypropylene Substances 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000011161 development Methods 0.000 description 3
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- 150000002500 ions Chemical class 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
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- 238000002474 experimental method Methods 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000011268 mixed slurry Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- 229920001155 polypropylene Polymers 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
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- 230000009466 transformation Effects 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 102000004310 Ion Channels Human genes 0.000 description 1
- 229910013063 LiBF 4 Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 229910001228 Li[Ni1/3Co1/3Mn1/3]O2 (NCM 111) Inorganic materials 0.000 description 1
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- NDPGDHBNXZOBJS-UHFFFAOYSA-N aluminum lithium cobalt(2+) nickel(2+) oxygen(2-) Chemical compound [Li+].[O--].[O--].[O--].[O--].[Al+3].[Co++].[Ni++] NDPGDHBNXZOBJS-UHFFFAOYSA-N 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910001593 boehmite Inorganic materials 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 239000006182 cathode active material Substances 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910021385 hard carbon Inorganic materials 0.000 description 1
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000037427 ion transport Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 1
- 229910002102 lithium manganese oxide Inorganic materials 0.000 description 1
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 1
- VLXXBCXTUVRROQ-UHFFFAOYSA-N lithium;oxido-oxo-(oxomanganiooxy)manganese Chemical compound [Li+].[O-][Mn](=O)O[Mn]=O VLXXBCXTUVRROQ-UHFFFAOYSA-N 0.000 description 1
- URIIGZKXFBNRAU-UHFFFAOYSA-N lithium;oxonickel Chemical compound [Li].[Ni]=O URIIGZKXFBNRAU-UHFFFAOYSA-N 0.000 description 1
- 229910001425 magnesium ion Inorganic materials 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000002931 mesocarbon microbead Substances 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 229910021384 soft carbon Inorganic materials 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000009461 vacuum packaging Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000004804 winding 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
-
- 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
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
-
- 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
-
- 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
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
-
- 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
- H01M2004/028—Positive 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention belongs to the technical field of secondary batteries, and particularly relates to a positive plate, a secondary battery and an electric device, which comprise a positive current collector and a positive active coating arranged on at least one surface of the positive current collector, wherein the positive active coating comprises a positive active substance, a binder and conductive carbon, and the positive active coating satisfies the following relational expression: -30.225 < - (-0.388 PD + 1.155) > BETsp/(12 BET) < 1.920; PD represents the compacted density of the positive active coating layer; BET represents a specific surface area of the positive electrode active material; BETsp represents the specific surface area of the conductive carbon. The positive plate prepared by the invention has excellent power performance and service life when being applied to a secondary battery.
Description
Technical Field
The invention belongs to the technical field of secondary batteries, and particularly relates to a positive plate, a secondary battery and an electric device.
Background
With the improvement of global exhaust emission requirements, the energy power system transformation of the automobile industry in the 21 st century is imperative, and the electric vehicle becomes the inevitable choice for the energy power system transformation. The hybrid electric vehicle has both oil consumption and emission, and therefore will become the mainstream of development in a relatively long period in the future, and the high-power lithium ion battery for the hybrid electric vehicle becomes the key of industrial development.
In view of the above, a lithium ion battery that can continuously provide high power output power while maintaining a long life is provided.
Disclosure of Invention
One of the objects of the present invention is: aiming at the defects of the prior art, the positive plate is provided, and has good cycle life and high power output capability.
In order to achieve the purpose, the invention adopts the following technical scheme:
the utility model provides a positive plate, includes the anodal mass flow body and sets up in the anodal active coating of the anodal mass flow body on at least one surface, anodal active coating includes anodal active material, binder and conductive carbon, anodal active coating satisfies following relational expression:
-30.225＜(-0.388*PD+1.155)*BETsp/(12*BET positive electrode )＜1.920；
Wherein PD represents the compacted density of the positive active coating layer and has the unit of g/cm 3 ；
Wherein, BET Positive electrode Represents the specific surface area of the positive electrode active material in m 2 /g；
Wherein BETsp represents the specific surface area of the conductive carbon and has a unit of m 2 /g。
Preferably, the value range of the PD is 2.55-3.2 g/cm 3 。
Preferably, the BET Positive electrode Has a value range of 0.8 to 5m 2 /g。
Preferably, the BET Positive electrode Has a value range of 1.3 to 1.8m 2 /g。
Preferably, the BETsp ranges from 130m to 300m 2 /g。
Preferably, the BETsp ranges from 165m to 300m 2 /g。
The second purpose of the invention is: in order to overcome the defects of the prior art, the secondary battery is provided, and has good cycle performance and high power output capacity.
In order to achieve the purpose, the invention adopts the following technical scheme:
the utility model provides a secondary battery, includes positive plate, negative pole piece, barrier film, electrolyte and casing, the barrier film is separated positive plate with the negative pole piece, the casing is used for installing encapsulation with positive plate, barrier film, negative pole piece, electrolyte, the positive plate is foretell positive plate.
Preferably, the negative electrode sheet comprises a negative electrode current collector and a negative electrode active coating arranged on at least one surface of the negative electrode sheet current collector.
Preferably, the electrolyte comprises a solvent and a lithium salt, wherein the solvent is an organic solution obtained by mixing ethylene carbonate, ethyl methyl carbonate and diethyl carbonate according to a volume ratio of 0.5-2.
The third purpose of the invention is that: aiming at the defects of the prior art, the electric device is provided, and has good cycle performance and high power output capability.
An electric device includes the secondary battery.
The power utilization devices of the present application include, but are not limited to: a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a cellular phone, a portable facsimile machine, a portable copier, a portable printer, a headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, a power-assisted bicycle, a lighting apparatus, a toy, a game machine, a clock, an electric tool, a flashlight, a camera, a large-sized household battery or a lithium ion capacitor, and the like.
Compared with the prior art, the invention has the beneficial effects that: according to the invention, through designing the compacted density of the positive active coating and the specific surface area of the positive active substance and the conductive carbon, the prepared positive plate has excellent power performance and service life when applied to a secondary battery.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.
The utility model provides a positive plate, includes the anodal mass flow body and sets up in the anodal active coating on the anodal mass flow body at least one surface, anodal active coating includes anodal active material, binder and conductive carbon, anodal active coating satisfies following relational expression:
-30.225＜(-0.388*PD+1.155)*BETsp/(12*BET positive electrode )＜1.920；
Wherein PD represents the compacted density of the active coating layer of the positive electrode and has the unit of g/cm 3 ；
Wherein, BET Positive electrode Represents the specific surface area of the positive electrode active material in m 2 /g；
Wherein BETsp represents the specific surface area of the conductive carbon in m 2 /g。
According to the relation, the compacted density of the positive plate, the specific surface area of the positive active material and the specific surface area of the conductive carbon black are designed and matched, so that the prepared secondary battery has excellent power performance and service life. The compaction density is the weight of powder in unit volume after the pole piece is rolled, the compaction density is related to the rebound size of the pole piece, and meanwhile, the specific surface area of active substances and conductive carbon of the battery in the rebound process affects the power and the service life of the lithium ion battery. The inventor discovers through a large amount of researches that the compaction density of the positive pole piece of the secondary battery, the specific surface area of the positive active material and the conductive carbon have great influence on the power performance of the battery, and the power performance and the service life of the battery can be effectively improved by reasonably matching and designing the positive active material and the conductive carbon.
The inventors summarized and proposed important empirical formulas related to secondary battery design through a large number of experiments: -30.225 < (-0.388 PD + 1.155) BETsp/(12 BET) Positive electrode ) < 1.920. When the secondary battery is designed, a plurality of empirical formulas are used as guidance, and the positive electrode compaction density, the positive electrode active substance and the conductive carbon specific surface area are selected and designed in a specific value range, so that the designed battery has excellent power performance and service life. This can avoid a large amount of DOE experiments, practices thrift battery development time and cost. Preferably, the relation is suitable for lithium ion batteries and sodium ion batteriesCalcium ion batteries, magnesium ion batteries, preferably, suitable for lithium ion batteries. More preferably, the secondary battery satisfies the following formula: -0.330 < (-0.388 PD + 1.155) BETsp/(12 BET) Positive electrode )＜1.02。
In some embodiments, the PD ranges from 2.55 to 3.2g/cm3. When the lithium ion battery is charged and discharged, lithium ions are separated and embedded between the positive electrode material and the negative electrode material, and the separation and embedding processes of the lithium ions are closely related to the compaction density of the positive electrode plate. On one hand, the compaction density is small, the liquid absorption capacity of the positive electrode is improved, and ion channels are increased, so that the ion transmission is improved; however, when the compaction density is too low, the ion transport distance is increased, the inter-particle distance is increased, the conductivity is increased, the dynamic performance is weakened, and the internal resistance is increased. On the other hand, the positive pole piece has high compaction density, active substance particles are tightly contacted with each other, an electronic conductive network in the pole piece is perfect, and the internal resistance is reduced; however, the pole piece is seriously rebounded in the circulation process due to too high compaction density, and particles among the active materials of the positive electrode are mutually stripped due to the contact chain fracture of the conductive carbon, the adhesive and the positive electrode material, so that the charge transfer resistance is increased, the rate capability and the circulation performance of the battery are deteriorated, and in addition, the particles are broken due to too high compaction density, and the liquid retaining amount of the electrolyte is reduced. Preferably, the value range of the PD is 2.55-3.2 g/cm 3 Preferably, the range of PD is 2.83-3.15, 2.9-3.1, 2.95-3.0, more preferably, the range of PD is 2.55g/cm 3 、2.65g/cm 3 、2.7g/cm 3 、2.76g/cm 3 、2.83g/cm 3 、2.89g/cm 3 、2.95g/cm 3 、2.98g/cm 3 、3.05g/cm 3 、3.09g/cm 3 、3.12g/cm 3 、3.15g/cm 3 、3.2g/cm 3 。
In some embodiments, the BET Positive electrode Has a value range of 0.8 to 5m 2 (ii) in terms of/g. Preferably, the BET Positive electrode Has a value range of 1.3-1.8 m 2 (ii) in terms of/g. Preferably, BET Positive electrode Has a value range of 0.8 to 5m 2 /g、1.1～5m 2 /g、1.3～5m 2 /g、1.5～4.5m 2 /g、1.8～4.2m 2 /g、2.1～4.0m 2 /g、2.8～3.5m 2 /g、3.2～4.0m 2 /g、3.5～4.0m 2 /g、3.5～3.8m 2 Per g, preferably BET Positive electrode Is 0.8m 2 /g、1.1m 2 /g、1.3m 2 /g、1.8m 2 /g、2.5m 2 /g、3.6m 2 /g、4.5m 2 /g、5m 2 /g。
In the above formula, the BET positive electrode represents the specific surface area of the positive electrode active material. The positive electrode active material having a small particle diameter has a large specific surface area, and thus has a large contact area with an electrolyte, which shortens a diffusion path of lithium ions, and facilitates the desorption of lithium ions in the material at a high current density, so that the rate capability of the material having a small particle diameter is good. The particle size of the positive active material particles is increased, so that the ion transmission distance can be effectively reduced, and the power performance of the battery is improved. The larger the pole piece compaction density is, the more serious rebound of the pole piece in the circulation process can be caused, the contact chain of the conductive carbon and the adhesive with the positive electrode material is broken, the contact between the active particles of the positive electrode and the conductive carbon is reduced, the gap is increased, the charge transfer resistance is increased, and the multiplying power performance and the circulation performance of the battery are deteriorated. The larger the specific surface area of the anode material is, the contact with the conductive carbon can be increased, and a good conductive network can be maintained. When the specific surface area is increased, the decrease of the density of the material is inevitable, and further the density of the electrode is reduced, so that the increase of the specific surface area of the material is not unlimited. Of course, if a nano-sized cathode active material is used, the electrode density is significantly reduced, and although the rate performance is improved, the safety performance of the battery is affected, such as side reactions with an electrolyte increase and the difficulty of slurry dispersion increases in a slurry preparation process. So that the specific surface area BET of the positive electrode active material Positive electrode The value range of (A) is controlled between 0.8 and 5m 2 Between/g, more preferably 1.3m 2 /g≤BET Positive electrode ≤1.8m 2 /g。BET Positive electrode Has a value range of 1.3-1.5 m 2 /g、1.3～1.5m 2 /g、1.3～1.4m 2 /g、1.3～1.35m 2 Per g, in particular BET Positive electrode Is 1.3m 2 /g、1.32m 2 /g、1.34m 2 /g、1.4m 2 /g、1.45m 2 /g、1.5m 2 /g、1.56m 2 /g、1.7m 2 /g、1.75m 2 /g、1.8m 2 /g。
In some embodiments, the BETsp has a value ranging from 130m to 300m 2 (iv) g. Preferably, the value range of the BETsp is 165-300 m 2 (ii) in terms of/g. The value range of BETsp is 130-300 m 2 /g、140～300m 2 /g、150～300m 2 /g、165～300m 2 /g、170～300m 2 /g、180～300m 2 /g、190～300m 2 /g、200～300m 2 /g、220～280m 2 /g、240～280m 2 /g、240～250m 2 (iv)/g, in particular, BETsp takes the value 130m 2 /g、140m 2 /g、160m 2 /g、165m 2 /g、169m 2 /g、180m 2 /g、210m 2 /g、240m 2 /g、280m 2 /g、300m 2 /g。
In the above relation, the BETsp is the specific surface area of the conductive carbon (conductive carbon black SP) in the positive electrode active coating layer. SP is conductive carbon black powder prepared by a furnace-black-like method, is a primary aggregate with the diameter of about 40nm agglomerated into 150-200 nm, is small in particle size, large in specific surface area, high in structure, clean in surface (few compounds), and is dispersed in active substances to form a multi-branched conductive network, so that the physical internal resistance of the battery can be reduced, and the electronic conductivity can be improved. On one hand, the larger the specific surface area of the conductive carbon is, the more the conductive contact between the active substances of the positive electrode is increased, the electron conductivity is improved, namely, microcurrent is collected between the active substances and the current collector, the conductive network in the electrode is perfected, the internal resistance is reduced, and the power performance is optimized; the pole piece is more compacted, so that the pole piece rebounds in the circulation process, the contact chain of the conductive carbon and the adhesive with the positive electrode material is broken, the contact among active particles of the positive electrode is reduced, the gap is increased, the charge transfer resistance is increased, and the multiplying power performance and the circulation performance of the battery are deteriorated. The branched conductive carbon having a larger specific surface area increases contact with the positive electrode active particles, and forms a favorable conductive network. On the other hand, the larger the surface area of the conductive carbon, the larger the viscosity in the slurry, and the poorer the dispersibilityAffecting the coating process. Therefore, the value range of BETsp is controlled between 130m and 300m 2 (ii) g, more preferably 165 to 200m 2 (ii) in terms of/g. Specifically, the BETsp value is 165m 2 /g、170m 2 /g、180m 2 /g、190m 2 /g、200m 2 /g。
The compaction density of the positive pole piece of the secondary battery, the specific surface area of the positive active material and the conductive carbon have great influence on the power performance of the battery, and the power performance and the service life of the battery can be effectively improved by reasonably matching and designing the positive pole piece of the secondary battery and the positive active material. The compaction density of the positive pole piece is increased, the active substance particles are tightly contacted with each other, the electronic conductive network in the pole piece is perfect, and the internal resistance is reduced; however, the pole piece rebounds in the circulation process due to too high compaction density, and contact chains of the conductive carbon and the adhesive with the positive electrode material are broken, so that particles among the positive electrode active materials are mutually stripped, the charge transfer resistance is increased, and the multiplying power performance and the circulation performance of the battery are deteriorated; the conductive carbon powder with proper specific surface area can reduce the internal resistance of the battery, improve the conductivity of electrons and ensure good dynamic performance of the battery. The positive active material with proper specific surface area increases the contact area with the electrolyte, so that the diffusion path of lithium ions is shortened, the desorption of the lithium ions in the material under high current density is facilitated, and the rate capability of the battery is improved.
The utility model provides a secondary battery, includes positive plate, negative pole piece, barrier film, electrolyte and casing, the barrier film is separated positive plate with the negative pole piece, the casing is used for installing encapsulation with positive plate, barrier film, negative pole piece, electrolyte, the positive plate is foretell positive plate.
The positive electrode sheet includes a positive active material, a conductive agent, a binder, and a current collector. The types of the positive electrode active material, the conductive agent, the binder and the current collector are not particularly limited, and can be selected according to actual requirements. For example, the positive active material may be selected from lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt aluminum oxide, olivine-structured lithium-containing phosphate, and the like; the current collector can be selected from aluminum foil, carbon-coated aluminum foil, nickel mesh and the like.
In the above lithium ion battery, the negative electrode sheet includes a negative electrode active material, a conductive agent, a binder, a dispersant, and a current collector. The types of the negative electrode active material, the conductive agent, the binder, the dispersant, and the current collector are not particularly limited and may be selected according to actual needs. For example, the negative active material may be selected from graphite, soft carbon, hard carbon, mesocarbon microbeads, silicon-based materials, and the like.
The isolating membrane is a PE or PP or composite material polymer film and is arranged between the positive plate and the negative plate. In the above lithium ion battery, the kind of the separator is not particularly limited, and may be selected according to actual requirements. Preferably, the isolating film can be selected from polyethylene film, polypropylene film, polyvinylidene fluoride film, non-woven fabric and the like; while the barrier film may have different coating layers. Such as alumina coatings, boehmite coatings, PVDF coatings, and the like.
In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative active coating disposed on at least one surface of the negative electrode sheet current collector.
In some embodiments, the electrolyte comprises a solvent and a lithium salt, wherein the solvent is an organic solution obtained by mixing ethylene carbonate, ethyl methyl carbonate and diethyl carbonate in a volume ratio of 0.5-2. Lithium salt optional LiPF 6 、LiTFSi、LiBF 4 And the like.
In the invention, the parameters of the cold pressing process of the positive plate, such as the cold pressing speed, the cold pressing temperature, the cold pressing pressure, the cold pressing times and the like, can influence the compaction density of the positive plate, so that the compaction density of the positive plate and the specific surface area of the positive active material can be adjusted by selecting a proper positive material by controlling the parameters of the cold pressing process of the positive plate. The specific surface area of the conductive carbon (conductive carbon black SP) in the positive electrode active coating layer can be adjusted by selecting an appropriate conductive carbon.
An electric device includes the secondary battery.
Example 1:
preparing a positive plate: the preparation method of the positive plate comprises the following steps:
1) Stirring: mixing a positive electrode active material NCM111, a conductive agent SP and a binder PVDF according to a certain mass ratio, adding NMP, and stirring by a homogenizer to form uniformly and stably mixed slurry;
2) Coating: and uniformly coating the obtained slurry on a current collector aluminum foil, and drying and cold-pressing for later use.
3) Cold pressing: carrying out cold pressing treatment on the dried positive pole piece under certain pressure and roll gap;
4) Slitting: and cutting the cold-pressed positive pole piece to a specified size for later use.
In the above-mentioned positive electrode sheet preparation process, the compaction density of the positive electrode sheet can be adjusted by adjusting cold pressing process parameters, such as cold pressing pressure, etc., in the cold pressing step.
Preparing a negative plate:
mixing a negative active material graphite, a conductive agent SP, a binder LA133 aqueous binder and a dispersant CMC according to a certain mass ratio, adding deionized water, and stirring by a homogenizer to form uniformly and stably mixed slurry; and uniformly coating the obtained slurry on a current collector copper foil, drying and cold pressing for later use.
Preparing an electrolyte:
ethylene Carbonate (EC), ethyl Methyl Carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1 6 Dissolved in the mixed organic solvent to prepare an electrolyte with the concentration of 1.2 mol/L.
And (3) isolation film: a polypropylene film with a thickness of 16 μm was selected as the separator.
Preparing a lithium ion battery: stacking the positive plate, the isolating membrane and the negative plate in sequence to enable the isolating membrane to be positioned between the positive plate and the negative plate to play an isolating role, and then winding to obtain a battery cell; and (3) placing the battery core in an outer packaging shell, drying, injecting electrolyte, and performing vacuum packaging, standing, formation, shaping and other processes to obtain the 8Ah lithium ion battery.
See example 1 the following examples 2-11 were set up with the exception of the compacted density of the positive electrode sheet, the specific surface area of the positive electrode active material and the specific surface area of the conductive carbon, see in particular table 1 below.
Electrical Performance testing
1) And (3) power testing: the lithium ion batteries obtained in examples 1 to 11 were subjected to 1045W high-power discharge.
2) And (3) cycle testing: charging the lithium ion secondary battery to 4.2V at a constant current of 0.5C at 25 ℃, standing for 30min, then discharging to 2.8V at a constant current of 1C, standing for 30min, which is a discharge cycle process, wherein the discharge capacity is an initial discharge capacity, and recording the number of cycles of the battery when the discharge capacity decays to 80% of the initial capacity.
3) And (4) high-temperature storage test: charging the lithium ion secondary battery to 4.2V at a constant current of 1C and a cutoff current of 0.05C at 25 ℃, standing for 30min, then discharging to 2.8V at a constant current of 1C, recording the capacity as C0 (initial capacity), and standing for 30min; and (3) placing the battery cell into a 60 ℃ high-temperature box, storing for 90 days, and testing the residual capacity C1 and the recovery capacity C2 every 30 days. The test of the residual capacity C1 was that after standing at 25 ℃ for 2h, 1C was discharged at constant current to 2.8V, and was recorded as a capacity C1 (residual capacity), then standing 30min,1c was charged at constant current and constant voltage to 4.2V, standing 30min,1c was discharged at constant current to 2.8V, and a capacity was recorded as C2, and the recovery rate of the capacity after 90 days of storage was = C2 (day 90)/C0.
4) Dynamic performance test
And (3) repeating the lithium ion batteries prepared in the examples and the comparative examples for 10 times by fully charging at 4C and fully discharging at 1C, fully charging at 4C, disassembling the negative pole piece and observing the lithium precipitation condition on the surface of the negative pole piece. Wherein, the lithium precipitation area of the surface of the negative electrode of less than 5 percent is considered to be slightly lithium precipitation, the lithium precipitation area of the surface of the negative electrode of 5 percent to 40 percent is considered to be moderately lithium precipitation, and the lithium precipitation area of the surface of the negative electrode of more than 40 percent is considered to be severely lithium precipitation.
The lithium ion batteries obtained in examples 1 to 11 were subjected to a 1045W high-power discharge time test.
TABLE 1
As shown by comparing examples 1-11 and comparative examples 1-2 in Table 1, the positive electrode sheet satisfies-30.225 < - (-0.388 > PD + 1).155)*BETsp/(12*BET Positive electrode ) When the temperature is less than 1.920, the prepared secondary battery has better performance, longer cycle life and larger power output. While the secondary batteries prepared in comparative examples 1 and 2 do not satisfy the above relational expression, when the prepared secondary batteries are subjected to 1045W high-power discharge test, the discharge time is only 3.2 seconds and 4.5 seconds, and the high-temperature storage capacity retention rates are 92% and 92.5%, and medium lithium deposition occurs.
As can be seen from the comparison of examples 1 to 4, when the compacted density of the positive electrode active coating layer, the specific surface area of the positive electrode active material, and the specific surface area of the conductive carbon satisfy the following relationships: -30.225 < (-0.388 PD + 1.155) BETsp/(12 BET) Positive electrode ) Less than 1.920, the discharge time of the secondary battery is longest when the discharge test is carried out at the high power of 1045W, and the discharge with the high power and the longer time can be realized.
From comparison of examples 1 and 5 to 8, it is found that when the compacted density of the positive electrode sheet is the same as the specific surface area of the conductive carbon, the discharge time of the prepared secondary battery is increased and then decreased when the discharge test is performed at 1045W high power with the increase of the specific surface area of the positive electrode active material, and when the specific surface area of the positive electrode active material is set to 6m 2 At the time of/g, the high-power discharge time is the longest and reaches 10.8 seconds.
From comparison of examples 1 and 9 to 11, it was found that as the specific surface area of the conductive carbon increases, the discharge time of the prepared secondary battery was increased and then decreased when the discharge test was performed at a high power of 1045W, and when the specific surface area of the positive electrode active material was set to 320m 2 At the time of/g, the high-power discharge time is the longest and reaches 10.7 seconds.
Variations and modifications to the above-described embodiments may become apparent to those skilled in the art to which the invention pertains based upon the disclosure and teachings of the above specification. Therefore, the present invention is not limited to the above-mentioned embodiments, and any obvious modifications, substitutions or alterations based on the present invention will fall within the protection scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (10)
1. The utility model provides a positive plate, its characterized in that includes the anodal mass flow body and sets up in the anodal active coating on the at least one surface of anodal mass flow body, anodal active coating includes anodal active material, binder and conductive carbon, anodal active coating satisfies following relational expression:
-30.225＜(-0.388*PD+1.155)*BETsp/(12*BET positive electrode )＜1.920；
Wherein PD represents the compacted density of the active coating layer of the positive electrode and has the unit of g/cm 3 ；
Wherein BET Positive electrode Represents the specific surface area of the positive electrode active material in m 2 /g；
Wherein BETsp represents the specific surface area of the conductive carbon and has a unit of m 2 /g。
2. The positive electrode sheet according to claim 1, wherein the PD has a value in the range of 2.55 to 3.2g/cm 3 。
3. The positive electrode sheet according to claim 1, wherein the BET Positive electrode Has a value range of 0.8 to 5m 2 /g。
4. The positive electrode sheet according to claim 3, wherein the BET Positive electrode Has a value range of 1.3-1.8 m 2 /g。
5. The positive electrode sheet according to claim 1, wherein the BETsp has a value ranging from 130 to 300m 2 /g。
6. The positive electrode sheet according to claim 5, wherein the BETsp has a value ranging from 165 to 300m 2 /g。
7. A secondary battery is characterized by comprising a positive plate, a negative plate, a separation film, electrolyte and a shell, wherein the positive plate and the negative plate are separated by the separation film, the shell is used for installing and packaging the positive plate, the separation film, the negative plate and the electrolyte, and the positive plate is the positive plate in any one of claims 1 to 6.
8. The secondary battery according to claim 7, wherein the negative electrode tab comprises a negative electrode current collector and a negative electrode active coating disposed on at least one surface of the negative electrode tab current collector.
9. The secondary battery according to claim 7 or 8, wherein the electrolyte comprises a solvent and a lithium salt, and the solvent is an organic solution obtained by mixing ethylene carbonate, ethyl methyl carbonate and diethyl carbonate in a volume ratio of 0.5-2.
10. An electric device comprising the secondary battery according to any one of claims 7 to 9.
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