CN118263497A - Secondary battery - Google Patents
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- CN118263497A CN118263497A CN202410532866.0A CN202410532866A CN118263497A CN 118263497 A CN118263497 A CN 118263497A CN 202410532866 A CN202410532866 A CN 202410532866A CN 118263497 A CN118263497 A CN 118263497A
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- 239000007774 positive electrode material Substances 0.000 claims description 16
- 239000007773 negative electrode material Substances 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 4
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- 229910000881 Cu alloy Inorganic materials 0.000 claims description 3
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- 230000001105 regulatory effect Effects 0.000 abstract description 2
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 13
- DVATZODUVBMYHN-UHFFFAOYSA-K lithium;iron(2+);manganese(2+);phosphate Chemical compound [Li+].[Mn+2].[Fe+2].[O-]P([O-])([O-])=O DVATZODUVBMYHN-UHFFFAOYSA-K 0.000 description 12
- 230000014759 maintenance of location Effects 0.000 description 9
- 239000002002 slurry Substances 0.000 description 9
- 229910000572 Lithium Nickel Cobalt Manganese Oxide (NCM) Inorganic materials 0.000 description 8
- FBDMTTNVIIVBKI-UHFFFAOYSA-N [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] Chemical compound [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] FBDMTTNVIIVBKI-UHFFFAOYSA-N 0.000 description 8
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- 230000002457 bidirectional effect Effects 0.000 description 4
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- 239000004743 Polypropylene Substances 0.000 description 2
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 description 2
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
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- 238000009831 deintercalation Methods 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 230000005518 electrochemistry Effects 0.000 description 1
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- Cell Electrode Carriers And Collectors (AREA)
- Secondary Cells (AREA)
Abstract
The application discloses a secondary battery, and belongs to the technical field of batteries. According to the product, the mesh current collector in the positive and negative current collectors is built by the current collector wires which are interwoven into the mesh shape, and the wire diameter, the aperture and the hole density of the mesh current collector and the coating thickness of the conductive outer layer are reasonably regulated, so that the positive and negative current collector builds an electronic conductive network in the charging and discharging process of the secondary battery, and meanwhile, the contact area with an active substance is large, the contact interface impedance is small, the conductive efficiency is high, and the secondary battery shows excellent comprehensive electrochemical performance.
Description
Technical Field
The application relates to the technical field of batteries, in particular to a secondary battery.
Background
In the secondary battery, most of interface contact between the active material coated with the conductive layer on the surface of the current collector of the metal foil and the current collector is concentrated on a two-dimensional plane, so that improvement effect on improving conductivity is limited, and the conductivity of some commercial active materials is lower, so that the interface contact area between the active material and the current collector needs to be increased, the conductivity is increased, and the electrochemical performance of the secondary battery is further improved.
Disclosure of Invention
The application aims to overcome the defects of the prior art and provide a secondary battery, the product constructs a net-shaped current collector in a positive and negative current collector by interweaving net-shaped current collector wires, and reasonably regulates and controls the wire diameter, the aperture, the hole density and the coating thickness of a conductive outer layer of the net-shaped current collector, so that the positive and negative current collector constructs an electronic conductive network in the charging and discharging process of the secondary battery, and meanwhile, the secondary battery has large contact area with active substances, small contact interface impedance and high conductive efficiency, and shows excellent comprehensive electrochemical performance.
In order to achieve the above object, in a first aspect of the present application, there is provided a secondary battery comprising a positive electrode tab including a positive electrode current collector and a negative electrode tab including a negative electrode current collector, the positive electrode current collector and the negative electrode current collector each independently including a mesh current collector including a current collector wire and at least one conductive outer layer; the current collector wires are interwoven to form a net structure; the reticular current collector is provided with holes;
The secondary battery satisfies:
0.01≤[A1*(B1/C1)*D1+A2*(B2/C2)*D2]*107≤12.2；
wherein A1mm is the wire diameter of a current collector wire of a net current collector in the positive current collector;
A2 mm is the wire diameter of the current collector wire of the net current collector in the negative current collector;
b1 mm is the aperture of the net-shaped current collector in the positive current collector;
B2 mm is the aperture of the reticular current collector in the negative current collector;
c1 is square inch unit hole number of the net-shaped current collector in the positive current collector;
c2 is the square inch unit hole number of the net current collector in the negative current collector;
d1 μm is the thickness of the conductive outer layer in the positive current collector;
d2 μm is the thickness of the conductive outer layer in the negative electrode current collector.
As an embodiment of the present application, the A1mm satisfies: a is more than or equal to 0.02mm and less than or equal to 1mm and less than or equal to 0.15mm.
As an embodiment of the present application, the A2mm satisfies: a2mm or less is 0.02mm or less and 0.15mm or less.
As an embodiment of the present application, the B1mm satisfies: b is more than or equal to 0.01mm and less than or equal to 1mm and less than or equal to 0.15mm.
As an embodiment of the present application, the B2mm satisfies: b2mm is more than or equal to 0.01mm and less than or equal to 0.15mm.
As an embodiment of the present application, the C1 satisfies: 10000-C1 is less than or equal to 500000.
As an embodiment of the present application, the C2 satisfies: 10000-C2-500000.
As an embodiment of the present application, the D1 μm satisfies: d1 μm is less than or equal to 0.5 μm and less than or equal to 3 μm.
As an embodiment of the present application, the D2 μm satisfies: d2 μm is less than or equal to 0.5 μm and less than or equal to 3 μm.
As an embodiment of the present application, the current collector wire of the mesh current collector in the positive electrode current collector includes at least one of an aluminum wire and an aluminum alloy wire.
As an embodiment of the present application, the current collector wire of the mesh current collector in the negative electrode current collector is at least one of a copper wire and a copper alloy wire.
As an embodiment of the present application, the interweaving manner of the current collector filaments of the mesh current collector in the positive electrode current collector includes plain interweaving and twill interweaving.
As an embodiment of the present application, the interweaving mode of the current collector filaments of the mesh current collector in the negative electrode current collector includes plain interweaving and twill interweaving.
As an embodiment of the present application, the composition of the conductive outer layer includes at least one of a binder and a conductive agent.
As an embodiment of the present application, the positive electrode sheet further includes a positive electrode active material layer disposed on the positive electrode current collector; and/or the negative electrode plate further comprises a negative electrode active material layer, and the negative electrode active material layer is arranged on the negative electrode current collector.
In a second aspect of the present application, there is provided an electric device including the secondary battery as a power supply source of the electric device.
The application has the beneficial effects that:
The application provides a secondary battery, which constructs a reticular current collector in a positive and negative current collector by interweaving reticular current collector wires, and reasonably regulates and controls the wire diameter, the aperture density and the coating thickness of a conductive outer layer of the reticular current collector, so that the positive and negative current collector constructs an electronic conductive network in the charging and discharging process of the secondary battery, and meanwhile, the secondary battery has large contact area with active substances, small contact interface impedance and high conductive efficiency, and shows excellent comprehensive electrochemical performance.
Drawings
Fig. 1 is a schematic view of a mesh current collector according to embodiment 1 of the present application.
Fig. 2 is a schematic cross-sectional structure of the positive electrode sheet according to embodiment 1 of the present application, wherein 1 is a mesh current collector, 2 is a conductive outer layer, and 3 is a positive electrode material.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions in the embodiments of the present application will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the application, the technical characteristics described in an open mode comprise a closed technical scheme composed of the listed characteristics and also comprise an open technical scheme comprising the listed characteristics.
In the present application, the numerical ranges are referred to as continuous, and include the minimum and maximum values of the ranges, and each value between the minimum and maximum values, unless otherwise specified. Further, when a range refers to an integer, each integer between the minimum and maximum values of the range is included. Further, when multiple range description features or characteristics are provided, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to include any and all subranges subsumed therein.
In the present application, the specific dispersing and stirring treatment method is not particularly limited.
The reagents or apparatus used in the present application are conventional products commercially available without the manufacturer's knowledge.
The application is further illustrated by the following specific examples:
The embodiment of the application provides a positive electrode material, which comprises a positive electrode plate and a negative electrode plate, wherein the positive electrode plate comprises a positive electrode current collector, the negative electrode plate comprises a negative electrode current collector, the positive electrode current collector and the negative electrode current collector respectively independently comprise a net-shaped current collector and at least one conductive outer layer, and the net-shaped current collector comprises current collector wires; the current collector wires are interwoven to form a net structure; the reticular current collector is provided with holes;
The secondary battery satisfies:
0.01≤[A1*(B1/C1)*D1+A2*(B2/C2)*D2]*107≤12.2；
wherein A1mm is the wire diameter of a current collector wire of a net current collector in the positive current collector;
A2 mm is the wire diameter of the current collector wire of the net current collector in the negative current collector;
b1 mm is the aperture of the net-shaped current collector in the positive current collector;
B2 mm is the aperture of the reticular current collector in the negative current collector;
c1 is square inch unit hole number of the net-shaped current collector in the positive current collector;
c2 is the square inch unit hole number of the net current collector in the negative current collector;
d1 μm is the thickness of the conductive outer layer in the positive current collector;
d2 μm is the thickness of the conductive outer layer in the negative electrode current collector.
The current secondary battery pole piece current collector can not give consideration to conductivity and overall structural stability of the pole piece, therefore, the inventor provides a secondary battery, the positive and negative pole piece current collector in the product comprises a net current collector formed by interweaving net current collector wires, the structure can construct an electronic conductive network in the charging and discharging process of the secondary battery, the contact area of the secondary battery with positive and negative pole active substances is increased by virtue of the large specific surface area brought by the three-dimensional morphology, meanwhile, the penetration of electrolyte is facilitated, the interface impedance is obviously reduced, and meanwhile, the advantages of high electronic conduction efficiency and high structural stability can be taken into consideration in the pole piece through design and regulation of the wire diameter, the aperture and the hole density of the net current collector and the thickness of a conductive outer layer, and finally, the secondary battery has excellent DCR performance, good low-temperature discharging performance and good cycle stability when testing electrochemical performance.
In some embodiments, the secondary battery satisfies: [ a1 ] (B1/C1) ×d1+a2 ] (B2/C2) ×d2] × 7 is a range value of one or any two of 0.01, 0.02, 0.03, 0.05, 0.08, 0.1, 0.2, 0.3, 0.5, 0.8, 1, 2, 3, 5, 8, 10, 12.2.
In some embodiments, the secondary battery satisfies:
0.04≤[A1*(B1/C1)*D1+A2*(B2/C2)*D2]*107≤10.85。
After two current collectors with the net-shaped current collector are constructed, the impedance, the ion electronic conduction efficiency and even the overall structural stability of the positive and negative pole pieces in the product can be changed by adjusting and controlling the pore structure of the net-shaped current collector and the characteristic parameters of the current collector wires, and optimizing the thickness of the conductive outer layer, and when the secondary battery meets the adjusting and controlling range, the comprehensive electrochemical performance of the product is better.
In some embodiments, the A1mm satisfies: a is more than or equal to 0.02mm and less than or equal to 1mm and less than or equal to 0.15mm.
Further preferably, the A1mm is a range value of one or any two of 0.02mm, 0.025mm, 0.03mm, 0.05mm, 0.06mm, 0.07mm, 0.1mm, 0.15 mm.
In some embodiments, the A2mm satisfies: a2mm or less is 0.02mm or less and 0.15mm or less.
Further preferably, the A2mm is a range value of one or any two of 0.02mm, 0.025mm, 0.03mm, 0.05mm, 0.06mm, 0.07mm, 0.1mm, 0.15 mm.
In some embodiments, the B1mm satisfies: b is more than or equal to 0.01mm and less than or equal to 1mm and less than or equal to 0.15mm.
Further preferably, the B1mm is a range value of one or any two of 0.01mm, 0.02mm, 0.03mm, 0.05mm, 0.06mm, 0.07mm, 0.1mm, 0.15 mm.
In some embodiments, the B2mm satisfies: b2mm is more than or equal to 0.01mm and less than or equal to 0.15mm.
Further preferably, the B2mm is a range value of one or any two of 0.01mm, 0.02mm, 0.03mm, 0.05mm, 0.06mm, 0.07mm, 0.1mm, 0.15 mm.
In some embodiments, the C1 satisfies: 10000-C1 is less than or equal to 500000.
Further preferably, the C1 is a range value of one or any two of 10000, 22500, 40000, 90000, 100000, 122500, 160000, 250000, 403225, 500000.
In some embodiments, the C2 satisfies: 10000-C2-500000.
Further preferably, the C2 is a range value of one or any two of 10000, 22500, 40000, 90000, 100000, 122500, 160000, 250000, 403225, 500000.
When the square inch unit hole number of the net-shaped current collector in the positive electrode current collector and the negative electrode current collector is maintained in the preferable range, the net-shaped current collector not only can effectively support active substances and increase the contact area with the active substances, but also can efficiently construct a conductive network in the charge and discharge process, so that the conductivity of the whole pole piece is improved.
In some embodiments, the D1 μm satisfies: d1 μm is less than or equal to 0.5 μm and less than or equal to 3 μm.
Further preferably, the D1 μm is a range value of one or any two of 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm.
In some embodiments, the D2 μm satisfies: d2 μm is less than or equal to 0.5 μm and less than or equal to 3 μm.
Further preferably, the D2 μm is a range value of one or any two of 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm.
When the thicknesses of the conductive outer layers in the positive electrode current collector and the negative electrode current collector are set in the preferable ranges, the conductive outer layers can further reduce the interface impedance between the active material and the netlike current collector, and meanwhile, the ionic/electronic transmission of the active material is facilitated, and the comprehensive electrochemistry is further improved.
In some embodiments, the composition of the conductive outer layer includes at least one of a binder, a conductive agent.
Further preferably, the positive electrode current collector includes a first conductive outer layer, a mesh current collector, and a second conductive outer layer connected in sequence.
Further preferably, the negative electrode current collector includes a first conductive outer layer, a mesh current collector, and a second conductive outer layer connected in sequence.
Further preferably, the D1 μm satisfies: d1 μm is less than or equal to 1 μm and less than or equal to 2.5 μm;
And/or the D2 μm satisfies: d2 μm is less than or equal to1 μm and less than or equal to 2.5 μm.
When the two contact surfaces of the reticular current collector are provided with the conductive outer layers, the thickness of the conductive outer layers has a certain influence on the contact condition of the reticular current collector and the active substance and even the electrolyte, and when the thickness of the conductive outer layers in the bipolar current collector is set to be in the preferable range, the comprehensive electrochemical performance of the secondary battery is further improved.
In some embodiments, the current collector wire of the mesh current collector in the positive electrode current collector comprises at least one of an aluminum wire and an aluminum alloy wire.
In some embodiments, the current collector wire of the mesh current collector in the negative current collector is at least one of a copper wire and a copper alloy wire.
In some embodiments, the interweaving mode of the current collector wires of the mesh current collector in the positive current collector comprises plain interweaving and twill interweaving.
Further preferably, the plain weave is a plain bidirectional meandering wave-insulating weave.
In some embodiments, the interweaving mode of the current collector wires of the mesh current collector in the negative current collector comprises plain interweaving and twill interweaving.
Further preferably, the plain weave is a plain bidirectional meandering wave-insulating weave.
In some embodiments, the positive electrode sheet further comprises a positive electrode active material layer disposed on the positive electrode current collector; and/or the negative electrode plate further comprises a negative electrode active material layer, and the negative electrode active material layer is arranged on the negative electrode current collector.
Further preferably, the positive electrode active material layer contains a positive electrode material including at least one of lithium manganate, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganate, and lithium nickel cobalt aluminate.
Further preferably, the positive electrode material is lithium iron phosphate or lithium manganese iron phosphate.
Different active material positive electrode materials have certain difference in electron conduction contact modes of current collectors in the lithium deintercalation process, and when the positive electrode materials in the preferred range are selected, the secondary battery constructed by the positive and negative current collectors has more obvious electrochemical performance improvement.
Further preferably, the anode active material layer contains an anode material including at least one of graphite, graphene, and conductive carbon black.
In some embodiments, the secondary battery further includes a separator including any one of a polypropylene film, a polyethylene film, a polyvinylidene fluoride film, a spandex film, and an aramid film.
The application is further illustrated by the following specific examples:
Example 1
A secondary battery, the method of manufacturing the secondary battery comprising the steps of:
(1) Preparing a positive electrode plate:
(1.1) interweaving metal aluminum wires in a plain bidirectional tortuous wave-insulating bending interweaving mode to obtain a net-shaped current collector, mixing conductive carbon black and adhesive carboxymethyl cellulose according to a mass ratio of 5:5, adding deionized water to adjust the mixture into slurry with a solid content of 20%, coating conductive slurry on two sides of the net-shaped current collector in a gravure roller coating mode, and drying to obtain an anode current collector;
(1.2) taking lithium iron phosphate with the commercial particle size of D v 50 0=1.1 mu m as a positive electrode material, then mixing with acetylene black and polyvinylidene fluoride according to the mass ratio of 96:2:2, dispersing in N-methylpyrrolidone to prepare slurry, coating the slurry on a positive electrode current collector, drying, and rolling to obtain a positive electrode plate;
(2) Preparing a negative electrode plate:
(2.1) interweaving metal copper wires in a plain weave bidirectional tortuous wave-insulating bending interweaving mode to obtain a netlike current collector, then mixing conductive carbon black and a binder carboxymethyl cellulose according to a mass ratio of 5:5, adding deionized water to adjust the mixture into slurry with a solid content of 20%, coating conductive slurry on two sides of the netlike current collector in a gravure roller coating mode, and drying to obtain a negative current collector;
(1.2) taking artificial graphite with the commercial particle size of D v 50 0=11.5 mu m as a negative electrode material, then mixing the artificial graphite with the mass ratio of 96.5:0.7:1.8:1 with acetylene black, styrene-butadiene rubber and sodium carboxymethyl cellulose, dispersing the mixture in water to prepare slurry, coating the slurry on a negative electrode current collector, drying and rolling the slurry to obtain a negative electrode plate;
(3) Preparation of secondary battery:
The positive pole piece and the negative pole piece are combined with a commercial diaphragm (7 mu m PP basal membrane+3 mu m ceramic layer+5 mu m PVDF layer) to be coiled and hot pressed, the electrode lugs are welded, then the electrode lugs are placed in an aluminum plastic film and baked for 24 hours at 85 ℃, electrolyte (1 mol/L lithium hexafluorophosphate+ethylene carbonate (EC): diethyl carbonate (DEC) volume ratio is 1:1 solvent) is injected, and the secondary battery is obtained after standing, formation and capacity division.
The parameters of the secondary battery are shown in table 1.
Examples 2 to 18
A secondary battery was different from example 1 only in parameters as shown in table 1.
Example 19
The secondary battery differs from example 1 only in that lithium iron phosphate is replaced with lithium manganese iron phosphate when the positive electrode sheet is prepared.
Example 20
The secondary battery differs from example 1 only in that lithium iron phosphate is replaced with lithium nickel cobalt manganate when the positive electrode sheet is prepared.
Comparative examples 1 to 4
A secondary battery was different from example 1 only in parameters as shown in table 1.
Comparative example 5
The secondary battery differs from example 1 only in that the mesh-shaped current collector surface is not coated with a conductive coating.
TABLE 1
The secondary batteries of each example, comparative example, and comparative example were subjected to the following performance tests:
(1) Normal temperature DCR test: charging the secondary battery to 3.65V (lithium iron phosphate positive electrode)/4.35V (lithium manganese iron phosphate, lithium nickel cobalt manganese oxide positive electrode) at the rate of 0.33C at 25+/-2 ℃, discharging for 90min with the capacity of 0.33C, regulating to 50% SOC, performing constant-current pulse discharge at the rate of 5C for 10s, and calculating DCR= (voltage before pulse discharge-voltage after pulse discharge)/discharge current;
(2) Low temperature DCR test: charging the secondary battery to 3.65V (lithium iron phosphate anode)/4.35V (lithium manganese iron phosphate, lithium nickel cobalt manganese oxide anode) at the rate of 0.33C at the temperature of 25+/-2 ℃, discharging for 90min at the capacity of 0.33C, adjusting the temperature to 50% of SOC, placing the battery into a low-temperature box, adjusting the temperature to-20 ℃, discharging for 10s at the constant current of 0.33C, and calculating DCR= (voltage before pulse discharge-voltage after pulse discharge)/discharge current;
(3) -20 ℃ discharge capacity retention rate test: charging the secondary battery to 2.0V (lithium iron phosphate positive electrode)/2.5V (lithium manganese iron phosphate positive electrode)/2.8V (lithium nickel cobalt manganese oxide positive electrode) at 25±2 ℃, then charging 0.33C to 3.65V (lithium iron phosphate positive electrode)/4.35V (lithium manganese iron phosphate, lithium nickel cobalt manganese oxide positive electrode), and then discharging to 2.0V (lithium iron phosphate positive electrode)/2.5V (lithium manganese iron phosphate positive electrode)/2.8V (lithium nickel cobalt manganese oxide positive electrode) at 0.33C, recording an initial discharge capacity R1;
Charging the secondary battery to 3.65V (lithium iron phosphate positive electrode)/4.35V (lithium manganese iron phosphate, lithium nickel cobalt manganese oxide positive electrode) at 25+/-2 ℃, placing the secondary battery into a low-temperature box with the temperature of-20+/-2 ℃ for constant temperature and keeping for 4 hours, finally discharging to 2.0V (lithium iron phosphate positive electrode)/2.5V (lithium manganese iron phosphate positive electrode)/2.8V (lithium nickel cobalt manganese oxide positive electrode) at a discharge rate of 0.33 ℃, and recording a discharge capacity R2 of the battery; -20 ℃ capacity retention = R2/R1%100%
(4) And (3) testing the normal temperature circulation capacity retention rate: at 25+ -2deg.C, the secondary battery was subjected to a charge-discharge cycle test at a charge-discharge rate of 1C/1C in a voltage range of 2.0-3.65V (lithium iron phosphate positive electrode)/2.5-4.35V (lithium manganese iron phosphate positive electrode)/2.8-4.35V (lithium nickel cobalt manganese oxide positive electrode), and the capacity retention rate when the battery was cycled to 1000 times was recorded. 1000 times capacity retention = 1000 times discharge capacity/1 st discharge capacity x 100%
The test results are shown in Table 2.
TABLE 2
| Product(s) | Normal temperature DCR (mΩ) | Low temperature DCR (mΩ) | -20 ℃ Capacity retention (%) | 1000 Times capacity retention (%) |
| Example 1 | 23.2 | 330 | 43.5％ | 95.6％ |
| Example 2 | 23.2 | 335 | 43.0％ | 95.5％ |
| Example 3 | 23.8 | 345 | 42.8％ | 95.3％ |
| Example 4 | 24.5 | 352 | 42.5％ | 94.8％ |
| Example 5 | 25.6 | 388 | 41.7％ | 94.5％ |
| Example 6 | 24.0 | 362 | 42.9％ | 95.2％ |
| Example 7 | 24.0 | 365 | 42.7％ | 95.0％ |
| Example 8 | 24.1 | 366 | 42.6％ | 95.0％ |
| Example 9 | 25.4 | 372 | 42.0％ | 94.8％ |
| Example 10 | 25.6 | 380 | 41.0％ | 94.7％ |
| Example 11 | 25.8 | 396 | 38.5％ | 94.6％ |
| Example 12 | 25.9 | 405 | 33.5％ | 94.5％ |
| Example 13 | 26.0 | 420 | 32.5％ | 94.2％ |
| Example 14 | 27.2 | 420 | 36.7％ | 94.6％ |
| Example 15 | 23.2 | 330 | 43.4％ | 95.5％ |
| Example 16 | 23.1 | 328 | 43.6％ | 95.7％ |
| Example 17 | 22.8 | 325 | 44.0％ | 95.7％ |
| Example 18 | 22.7 | 323 | 43.9％ | 95.6％ |
| Example 19 | 28.0 | 340 | 38.7％ | 89.4％ |
| Example 20 | 18.8 | 287 | 73.2％ | 92.5％ |
| Comparative example 1 | 28.2 | 445 | 30.5％ | 93.8％ |
| Comparative example 2 | 29.0 | 450 | 31.0％ | 93.5％ |
| Comparative example 3 | 29.2 | 455 | 30.2％ | 94.3％ |
| Comparative example 4 | 28.5 | 450 | 30.8％ | 94.5％ |
| Comparative example 5 | 28.5 | 440 | 31.2％ | 94.0％ |
In tables 1 and 2, it can be seen from examples 1 to 20 and comparative examples 1 to 5 that when the positive and negative electrode current collectors are three-dimensional network and the corresponding wire diameters, pore numbers per square inch and thicknesses of the conductive coatings satisfy 0.01 ++a1 (B1/C1) ×+a2 (B2/C2) × D2 ]. Ltoreq.12.2, the contact area of the three-dimensional network current collector and the positive and negative electrode active materials is increased, an electron conductive network is constructed in the charge and discharge process, the electron transmission rate is improved, the interface impedance is reduced, the three-dimensional conductive network is simultaneously beneficial to ion transmission, the low-temperature discharge performance is improved, and the circulation stability is improved.
In tables 1 and 2, it is understood from examples 1 to 18 that by adjusting the wire diameter, the pore diameter, the number of pores per square inch and the thickness of the conductive outer layer of the positive and negative electrode net-shaped current collector, when the wire diameter of the current collector is 0.02 mm.ltoreq.A1 mm.ltoreq.0.066 mm,0.02 mm.ltoreq.A2 mm.ltoreq.0.066 mm, the pore diameter of 0.02 mm.ltoreq.B1 mm.ltoreq.0.104 mm,0.02 mm.ltoreq.B2 mm.ltoreq.0.104 mm, the number of pores per square inch is 22500.ltoreq.C1.ltoreq.403225, 22500.ltoreq.C2.ltoreq. 403225, the thickness of the conductive outer layer is 0.5 μm.ltoreq.D1μm.ltoreq.3μm, and the positive and negative electrode active material layer can be sufficiently contacted with the current collector, thereby facilitating the conduction of electrons, effectively reducing the interface impedance, improving the electrochemical properties, especially the low temperature DCR and the low temperature capacity retention rate is remarkably improved, compared with comparative examples 1 to 5. As is clear from examples 14 to 18, when D1 μm.ltoreq.D1 μm.ltoreq.2.5 μm and D2 μm.ltoreq.2.5 μm are 1 μm or less, too low a conductive coating increases the impedance as well, and the interface impedance is not significantly improved after the conductive coating reaches 2.5 μm, and the thickness of the coating needs to be controlled within a reasonable range.
In tables 1 and 2, it is apparent from examples 1 and 19 and 20 that the positive electrode active material materials are different, and the three-dimensional mesh current collector according to the present application has different electrochemical performance improvement effects, and the electrochemical performance improvement is more remarkable when the positive electrode active materials are lithium iron phosphate and lithium manganese iron phosphate.
As is apparent from the experimental results of comparative examples 1 to 20 and comparative examples 1 to 5, when 0.04 is less than or equal to [ A1 (B1/C1) d1+a2 (B2/C2) D2] 10 7 is less than or equal to 10.85, the DCR of the lithium iron phosphate system battery, especially the DCR at low temperature of-20 ℃, is significantly improved, which means that the contact resistance of the active material and the current collector in the pole piece is significantly reduced and the conductivity is improved under the preferred condition, and the normal temperature cycle performance is 1000 times with a cycle capacity retention rate of 94.5% or more, and the improvement effect on the lithium iron phosphate of the positive electrode active material with poor conductivity is more obvious.
Claims (10)
1. The secondary battery is characterized by comprising a positive electrode plate and a negative electrode plate, wherein the positive electrode plate comprises a positive electrode current collector, the negative electrode plate comprises a negative electrode current collector, and the positive electrode current collector and the negative electrode current collector respectively independently comprise a net-shaped current collector and at least one conductive outer layer; the net-shaped current collector comprises current collector wires, and the current collector wires are interwoven to form a net-shaped structure; the reticular current collector is provided with holes;
The secondary battery satisfies:
0.01≤[A1*(B1/C1)*D1+A2*(B2/C2)*D2]*107≤12.2；
wherein A1mm is the wire diameter of a current collector wire of a net current collector in the positive current collector;
A2 mm is the wire diameter of the current collector wire of the net current collector in the negative current collector;
b1 mm is the aperture of the net-shaped current collector in the positive current collector;
B2 mm is the aperture of the reticular current collector in the negative current collector;
c1 is square inch unit hole number of the net-shaped current collector in the positive current collector;
c2 is the square inch unit hole number of the net current collector in the negative current collector;
d1 μm is the thickness of the conductive outer layer in the positive current collector;
d2 μm is the thickness of the conductive outer layer in the negative electrode current collector.
2. The secondary battery according to claim 1, wherein A1mm satisfies: a is more than or equal to 0.02mm and less than or equal to 1mm and less than or equal to 0.15mm; and/or, the A2mm satisfies: a2mm or less is 0.02mm or less and 0.15mm or less.
3. The secondary battery according to claim 1, wherein B1mm satisfies: a is more than or equal to 0.01mm and less than or equal to 1mm and less than or equal to 0.15mm; and/or, the B2mm satisfies: b2mm is more than or equal to 0.01mm and less than or equal to 0.15mm.
4. The secondary battery according to claim 3, wherein the C1 satisfies: 10000-C1-500000; and/or, the C2 satisfies: 10000-C2-500000.
5. The secondary battery according to claim 1, wherein the D1 μm satisfies: d1 μm is less than or equal to 0.5 μm and less than or equal to 3 μm; and/or, the D2 μm satisfies: d2 μm is less than or equal to 0.5 μm and less than or equal to 3 μm.
6. The secondary battery according to claim 1, wherein the current collector wire of the mesh current collector in the positive electrode current collector comprises at least one of an aluminum wire and an aluminum alloy wire; and/or the current collector wire of the net-shaped current collector in the negative current collector is at least one of a copper wire and a copper alloy wire.
7. The secondary battery according to claim 1, wherein the interlacing mode of the current collector wires of the mesh current collector in the positive electrode current collector includes plain interlacing and twill interlacing; and/or the interweaving mode of the current collector wires of the net-shaped current collector in the negative current collector comprises plain interweaving and twill interweaving.
8. The secondary battery of claim 1, wherein the composition of the conductive outer layer comprises at least one of a binder and a conductive agent.
9. The secondary battery of claim 1, wherein the positive electrode sheet further comprises a positive electrode active material layer disposed on the positive electrode current collector; and/or the negative electrode plate further comprises a negative electrode active material layer, and the negative electrode active material layer is arranged on the negative electrode current collector.
10. An electric device comprising the secondary battery according to any one of claims 1 to 9 as a power supply source of the electric device.
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