CN110504410B - Lithium ion battery and pole piece thereof - Google Patents
Lithium ion battery and pole piece thereof Download PDFInfo
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- CN110504410B CN110504410B CN201810478712.2A CN201810478712A CN110504410B CN 110504410 B CN110504410 B CN 110504410B CN 201810478712 A CN201810478712 A CN 201810478712A CN 110504410 B CN110504410 B CN 110504410B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
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- Y02E60/10—Energy storage using batteries
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Abstract
The invention discloses a lithium ion battery and a pole piece thereof, wherein the pole piece comprises a current collector and a diaphragm formed on the current collector, the diaphragm comprises active material layers, the active material layers comprise a first active material layer and a second active material layer which are positioned at two sides, and a third active material layer which is positioned in the middle, the particle size of the materials in the first active material layer and the second active material layer is smaller than that of the materials in the third active material layer, the first active material layer accounts for 1/5-3/8 of the width of the diaphragm, the second active material layer accounts for 1/5-3/8 of the width of the diaphragm, and the third active material layer accounts for 1/4-3/5 of the width of the diaphragm. Compared with the prior art, the lithium ion battery and the pole piece thereof have the advantages of strong liquid absorption capacity, high liquid absorption rate, high thermal stability and good cycle performance.
Description
Technical Field
The invention belongs to the field of batteries, and particularly relates to a lithium ion battery and a pole piece thereof.
Background
The liquid absorption capacity is an important parameter influencing the performance of the lithium ion battery, and the liquid absorption capacity of the battery is mainly limited by the liquid absorption capacity of the central area of the pole piece. At present, the common methods for solving the imbibition capacity mainly comprise the following methods: 1) the electrolyte is promoted to enter the pore channels among the particles by vacuumizing in the liquid injection stage and combining pressurization to assist the absorption of the electrolyte; 2) the high-temperature standing is used for assisting in soaking the electrolyte, and the electrolyte is allowed to soak into the gaps of the pole pieces due to the fact that the viscosity of the electrolyte is lower at the high temperature after standing for a period of time; 3) and injecting liquid for multiple times, namely injecting a certain amount of electrolyte to absorb the electrolyte, and then injecting more electrolyte for multiple times until the specified amount is reached. Although the method can enable the electrolyte to easily infiltrate the edge of the pole piece and gradually infiltrate towards the center of the pole piece, the longer the electrolyte infiltration path is, the more difficult the electrolyte infiltration path is, and when the middle area of the pole piece is sufficiently infiltrated, the too long time is consumed, and the requirement of rapidly preparing the battery can not be met.
In view of this, it is necessary to provide a lithium ion battery and a pole piece thereof, which have strong liquid absorption capability, fast liquid absorption rate, high thermal stability and good cycle performance.
Disclosure of Invention
The invention aims to: overcomes the defects of the prior art, and provides a lithium ion battery and a pole piece thereof with strong imbibition capability, high imbibition rate, high thermal stability and good cycle performance.
In order to achieve the purpose, the invention provides a lithium ion battery pole piece which comprises a current collector and a membrane formed on the current collector, wherein the membrane comprises active material layers, the active material layers comprise a first active material layer and a second active material layer which are positioned at two sides, and a third active material layer which is positioned in the middle, the particle size of materials in the first active material layer and the second active material layer is smaller than that of materials in the third active material layer, the first active material layer accounts for 1/5-3/8 of the width of the membrane, the second active material layer accounts for 1/5-3/8 of the width of the membrane, and the third active material layer accounts for 1/4-3/5 of the width of the membrane.
When the first active material layer and the second active material layer occupy too small width of the diaphragm, the material with larger particle diameter in the middle third active material layer is too much, and the large-current charge-discharge performance of the battery is difficult to ensure; when the first active material layer and the second active material layer occupy too large width of the membrane, the material with larger particle size in the middle third active material layer has less liquid absorption amount and poorer thermal stability because the particle size of the material in the first active material layer and the second active material layer is smaller and the width is too large, thereby influencing the long-term cycling stability of the battery.
As an improvement of the lithium ion battery pole piece, the first active material layer accounts for 1/4-1/3 of the width of the membrane, the second active material layer accounts for 1/4-1/3 of the width of the membrane, and the third active material layer accounts for 1/3-1/2 of the width of the membrane.
As an improvement of the lithium ion battery pole piece, the first active material layer accounts for 1/4 the width of the membrane, the second active material layer accounts for 1/4 the width of the membrane, and the third active material layer accounts for 1/2 the width of the membrane.
As an improvement of the lithium ion battery pole piece, the first active material layer accounts for 1/3 the width of the membrane, the second active material layer accounts for 1/3 the width of the membrane, and the third active material layer accounts for 1/3 the width of the membrane.
As an improvement of the lithium ion battery pole piece of the present invention, the difference between the particle size of the material in the third active material layer and the particle size of the material in the first active material layer and the particle size of the material in the second active material layer D50 is more than 20%.
As an improvement of the lithium ion battery pole piece of the invention, the thickness of the lithium ion battery pole piece is 20-200 μm, preferably 55-160 μm, and more preferably 80-140 μm.
As an improvement of the lithium ion battery pole piece, the first active material layer, the second active material layer and the third active material layer are in rectangular, square or parallelogram structures.
As an improvement of the lithium ion battery pole piece, the membrane further comprises a conductive layer or a functional material layer, the thickness of the conductive layer is not more than 10 microns, preferably 0.5-5 microns, and the thickness of the functional material layer is not more than 10 microns, preferably 0.5-5 microns.
As an improvement of the lithium ion battery pole piece, the diaphragm further comprises a conductive layer and a functional material layer, the conductive layer is formed on the surface of the current collector, and the functional material layer is formed on the surface of the conductive layer; or
The functional material layer is formed on the surface of the current collector, the conductive layer is formed on the surface of the functional material layer, the thickness of the conductive layer is not more than 10 microns, preferably 0.5-5 microns, and the thickness of the functional material layer is not more than 10 microns, preferably 0.5-5 microns.
As an improvement of the lithium ion battery pole piece, the conductive layer comprises a conductive agent, and the conductive agent is selected from at least one of conductive carbon, conductive graphite, conductive ink, ketjen black, carbon nanotubes, conductive carbon fibers and acetylene black; the functional material layer is one of an inorganic coating, an organic/inorganic composite coating and an organic coating.
As an improvement of the lithium ion battery pole piece, the conducting layer further comprises a binder, the binder is at least one selected from polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene and sodium carboxymethylcellulose, and the mass ratio of the conducting agent to the binder is 92-98: 2-8, preferably 94-96: 4-6.
As an improvement of the lithium ion battery pole piece, the organic component in the organic coating and the organic/inorganic composite coating is selected from one or more of polymers with the capability of leading lithium ions, high-melting-point polymers and flame-retardant polymers; the inorganic component in the inorganic coating and the organic/inorganic composite coating is at least one selected from aluminum oxide, aluminum oxyhydroxide, silicon dioxide, titanium dioxide, cerium dioxide, calcium carbonate, calcium oxide, zinc oxide, magnesium oxide, cerium titanate, calcium titanate, barium titanate, lithium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, lithium nitride and lithium lanthanum titanate.
As an improvement of the lithium ion battery pole piece, the organic component in the organic coating and the organic/inorganic composite coating is one or more of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, acrylonitrile-styrene-butadiene copolymer, polyacrylonitrile, polyethylacrylate, acrylic acid-styrene copolymer, acrylonitrile-butadiene copolymer, poly (m-phenylene isophthalamide), polyimide, poly (p-phenylene terephthalamide) and polymethyl acrylate.
In order to achieve the above object, the present invention further provides a lithium ion battery, which includes a cathode sheet, an anode sheet, a separation film spaced between the cathode sheet and the anode sheet, and an electrolyte, wherein at least one of the cathode sheet and the anode sheet is the above lithium ion battery electrode.
As an improvement of the lithium ion battery, the cathode plate is the lithium ion battery pole piece.
As an improvement of the lithium ion battery of the present invention, the cathode sheet includes a current collector and a membrane formed on the current collector, the membrane includes active material layers, the active material layers include a first active material layer and a second active material layer located at two sides, and a third active material layer located in the middle, and the materials in the first active material layer, the second active material layer, and the third active material layer are selected from one or more of a lithium cobaltate compound, a lithium nickel cobalt manganese compound, a lithium nickel cobalt aluminate compound, a lithium iron phosphate compound, a lithium manganese compound, a lithium iron manganese phosphate compound, and a lithium nickel manganese compound.
Compared with the prior art, the lithium ion battery and the pole piece thereof have the following technical effects:
1) active materials with smaller particle sizes are coated in the two side areas of the pole piece, and active materials with larger particle sizes are coated in the middle area, so that the gap between large particles is larger, more pore channels are provided, the infiltration rate of electrolyte of the pole piece can be improved, and the quick liquid absorption of a battery is facilitated;
2) aiming at the characteristic that the temperature of the battery is high in the middle and low on two sides, the active material with larger particle size is coated in the middle area, and the large-particle matter has lower specific surface area and fewer side reactions, so that the long-term cycle performance of the battery is facilitated;
3) the thermal stability and the long-term stability of the pole piece are improved, and the manufacturing efficiency and the safety performance of the battery are improved.
Drawings
FIG. 1 is a transverse cross-sectional view of a lithium ion battery electrode sheet according to the present invention.
10-a first active material layer; 20-a second active material layer; 30-third active material layer
Detailed Description
In order to make the objects, technical solutions and technical effects of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
Referring to fig. 1, the lithium ion battery electrode plate of the present invention includes a current collector and a membrane formed on the current collector, wherein the membrane includes active material layers, the active material layers include a first active material layer 10 and a second active material layer 20 located at two sides, and a third active material layer 30 located in the middle, the particle size of the materials in the first active material layer 10 and the second active material layer 20 is smaller than the particle size of the materials in the third active material layer 30, the first active material layer 10 occupies 1/5-3/8 of the width of the membrane, the second active material layer 20 occupies 1/5-3/8 of the width of the membrane, and the third active material layer 30 occupies 1/4-3/5 of the width of the membrane.
Example 1
Preparation of cathode sheet
1) Adding a cathode active material NCM111(D50 is 5.2 mu m), a conductive agent and PVDF into a solvent N-methyl pyrrolidone (NMP) according to a mass ratio of 97:2:1, uniformly stirring under the action of a vacuum stirrer to obtain cathode slurry, and uniformly coating the cathode slurry on one side of an aluminum foil to obtain a first cathode material layer; 2) adding a solvent N-methyl pyrrolidone (NMP) into a cathode active material NCM111(D50 is 8.6 mu m), a conductive agent and PVDF according to a mass ratio of 97:2:1, uniformly stirring under the action of a vacuum stirrer to obtain cathode slurry, and uniformly coating the cathode slurry on the middle position of an aluminum foil to obtain a third cathode material layer; 3) adding a cathode active material NCM111(D50 is 5.2 mu m), a conductive agent and PVDF into a solvent N-methylpyrrolidone (NMP) according to the mass ratio of 97:2:1, and uniformly stirring under the action of a vacuum stirrer to obtain cathode slurry; uniformly coating the cathode slurry on the other side of the aluminum foil to obtain a second cathode material layer; 4) and (3) airing the aluminum foil at room temperature, transferring the aluminum foil to a 90 ℃ oven for drying for 1h, and then performing cold pressing and slitting to obtain the cathode sheet with the zebra coating structure. The first cathode material layer, the second cathode material layer and the third cathode material layer respectively occupy 1/3 of the width of the membrane and are coated on two sides of the current collector (aluminum foil), and the first cathode active material layer, the second cathode active material layer and the third cathode active material layer are rectangular structures.
Anode sheet preparation
Mixing an anode active material graphite FSNC, a thickening agent carboxymethylcellulose sodium (CMC), a binder Styrene Butadiene Rubber (SBR) and a conductive agent according to a weight ratio of 95.5:1.2:1.8:1.5, adding solvent deionized water, and uniformly stirring under the action of a vacuum stirrer to obtain anode slurry; uniformly coating the anode slurry on a copper foil; and (3) airing the copper foil at room temperature, transferring the copper foil to a 120 ℃ oven for drying for 1h, and then carrying out cold pressing and slitting to obtain the anode sheet.
Preparation of electrolyte
At water content<In a 10ppm argon atmosphere glove box, a fully dried lithium salt LiPF6Dissolving in organic solvent, and mixing to obtain electrolyte. Wherein, LiPF6Is 1M. Wherein the organic solvent is a mixed solvent of ethylene carbonate, propylene carbonate and propyl propionate in a volume ratio of 1:1: 1.
Preparation of lithium ion battery
The cathode sheet, the isolating film and the anode sheet are sequentially stacked, the isolating film is positioned between the cathode sheet and the anode sheet to play an isolating role, then the cathode sheet and the anode sheet are cold-pressed and cut to be made into 4060D0 soft-package batteries, electrolyte is injected, and the lithium ion batteries are prepared through formation, aging and vacuum sealing.
Examples 2 to 11 are basically the same as example 1, except that the parameters relating to the respective substances are different, and specific parameters are shown in table 1.
Examples 12 to 15 are substantially the same as examples 1 to 11, except that a conductive layer is added to the examples 1 to 11, and the conductive layer is formed on a current collector aluminum foil, wherein the mass ratio of the conductive agent to the binder is 94: 6.
Examples 16 to 19 are substantially the same as examples 1 to 11, except that a functional material layer is added to the examples 1 to 11, and the functional material layer is formed on the current collector aluminum foil.
The embodiment 20 is basically the same as the embodiments 1 to 11, except that a conductive layer and a functional material layer are added on the basis of the embodiments 1 to 11, the conductive layer is formed on the current collector aluminum foil, the functional material layer is formed on the conductive layer, and the mass ratio of the conductive agent to the binder is 94: 6.
Example 21 is substantially the same as examples 1 to 11, except that a conductive layer and a functional material layer are added on the basis of examples 1 to 11, the functional material layer is formed on a current collector aluminum foil, and the conductive layer is formed on the functional material layer, wherein the mass ratio of the conductive agent to the binder is 94: 6.
The types and parameters of the substances of examples 1 to 21 are shown in Table 1.
Example 22
Preparation of cathode sheet
Adding a cathode active material NCM111, a conductive agent and PVDF into a solvent N-methyl pyrrolidone (NMP) according to a mass ratio of 97:2:1, uniformly stirring under the action of a vacuum stirrer to obtain cathode slurry, and uniformly coating the cathode slurry on an aluminum foil; and (3) airing the aluminum foil at room temperature, transferring the aluminum foil to a 90 ℃ oven for drying for 1h, and then performing cold pressing and slitting to obtain the cathode sheet.
Anode sheet preparation
1) Mixing an anode active material graphite CP5H (D50 is 5.5 mu m), a thickening agent sodium carboxymethyl cellulose (CMC) and a conductive agent according to a weight ratio of 95.5:1.2:1.8, adding solvent deionized water, stirring uniformly under the action of a vacuum stirrer, and finally adding a binder Styrene Butadiene Rubber (SBR) according to a mass ratio of 1.5 and stirring to obtain anode slurry; uniformly coating the anode slurry on one side of a copper foil to obtain a first anode material layer; 2) uniformly stirring an anode active material graphite CP7H (D50 is 7.8 mu m), a thickening agent carboxymethylcellulose sodium (CMC), a binder Styrene Butadiene Rubber (SBR) and a conductive agent according to the above proportion and method to obtain anode slurry; uniformly coating the anode slurry on the middle position of the copper foil to obtain a third anode material layer; 3) uniformly stirring an anode active material graphite CP5H (D50 is 5.5 mu m), a thickening agent carboxymethylcellulose sodium (CMC), a binder Styrene Butadiene Rubber (SBR) and a conductive agent according to the above proportion and method to obtain anode slurry; uniformly coating the anode slurry on the other side of the copper foil to obtain a second anode material layer; 4) and (3) airing the copper foil at room temperature, transferring the copper foil to a 120 ℃ oven for drying for 1h, and then carrying out cold pressing and slitting to obtain the anode. The first anode material layer, the second anode material layer and the third anode material layer respectively occupy 1/3 of the width of the diaphragm, and the first anode material layer, the second anode material layer and the third anode material layer are of rectangular structures.
Preparation of electrolyte
At water content<In a 10ppm argon atmosphere glove box, a fully dried lithium salt LiPF6Dissolving in organic solvent, and mixing to obtain electrolyte. Wherein, LiPF6Is 1M. Wherein the organic solvent is ethylene carbonate, propylene carbonate and propyl propionate which are 11:1 (volume ratio).
Preparation of lithium ion battery
The cathode sheet, the isolating film and the anode sheet are sequentially stacked, the isolating film is positioned between the cathode sheet and the anode sheet to play an isolating role, then the cathode sheet and the anode sheet are cold-pressed and cut to be made into 4060D0 soft-package batteries, electrolyte is injected, and the lithium ion batteries are prepared through formation, aging and vacuum sealing.
Examples 23 to 26 are basically the same as example 22, except that the parameters relating to the respective substances are different, and specific parameters are shown in table 2.
Example 27
Example 27 the cathode was the cathode of example 1 and the anode was the anode of example 22.
Example 28
Example 28 the cathode was the cathode of example 2 and the anode was the anode of example 23.
Example 29
Example 29 the cathode was the cathode of example 3 and the anode was the anode of example 24.
Data for cathodes and anodes for examples 27-29 are shown in Table 3.
TABLE 1 examples 1 to 21 relevant substance classes and parameters
TABLE 2 examples 22 to 26 relevant substance classes and parameters
TABLE 3 examples 27 to 29 cathodes and anodes
| Cathode electrode | Anode | |
| Example 27 | Example 1 cathode | EXAMPLE 22 Anode |
| Example 28 | Example 2 cathode | EXAMPLE 23 Anode |
| Example 29 | Example 3 cathode | EXAMPLE 24 Anode |
Comparative example 1
Adding a solvent N-methyl pyrrolidone (NMP) into a cathode active material NCM111(D50 is 5.2 mu m), a conductive agent and PVDF according to a mass ratio of 97:2:1, uniformly stirring under the action of a vacuum stirrer to obtain cathode slurry, and uniformly coating the cathode slurry on one side of an aluminum foil to obtain a small-particle-size cathode material layer; adding a solvent N-methyl pyrrolidone (NMP) into a cathode active material NCM111(D50 is 8.6 mu m), a conductive agent and PVDF according to a mass ratio of 97:2:1, uniformly stirring under the action of a vacuum stirrer to obtain cathode slurry, and uniformly coating the cathode slurry on the other side of the aluminum foil to obtain a large-particle-size cathode material layer; and (3) airing the aluminum foil at room temperature, transferring the aluminum foil to a 90 ℃ oven for drying for 1h, and then carrying out cold pressing and slitting to obtain the cathode sheet with the small-particle-size (D50 is 5.2 mu m) cathode material on one side and the large-particle-size (D50 is 8.6 mu m) cathode material on the other side. Wherein, the mass ratio of the small-particle-size cathode material to the large-particle-size cathode material is 1:2, the width and the thickness are the same as those of the embodiment 1, and the coating is coated on the two sides of the current collector aluminum foil. (wherein the small-particle-size cathode material layer refers to a material layer with a smaller particle size of the material in the same pole piece, and the large-particle-size cathode material layer refers to a material layer with a larger particle size of the material, which are in a mutual contrast relationship).
Comparative examples 2 and 3 are substantially the same as comparative example 1 except for the kind and particle size of the cathode material.
The types and parameters of the related substances of comparative examples 1 to 3 are shown in Table 4.
TABLE 4 species and parameters of related substances of comparative examples 1 to 3
Lithium ion battery performance testing
Cycle performance test
The lithium ion batteries prepared in examples 1 to 29 and the lithium ion batteries prepared in comparative examples 1 to 3 were tested according to the following methods:
charging the lithium ion battery to 4.2V at a constant current of 0.5C at a certain temperature, and then charging to 0.05C at a constant voltage; the cells were then discharged to 2.8V at a constant current of 0.5C, so that the charge/discharge was effected to reduce the cell capacity to 80% of the initial cell capacity, and the number of cycles (15 cells, averaged) was recorded, and the results of the cycle performance test are shown in table 5.
Imbibition test
Hang naked electric core on the support, the below discharges the electronic scale, places the container on the electronic scale, holds electrolyte. And moving the support downwards, immersing the bare cell into the electrolyte (the immersion depth is half of the height of the bare cell), recording the output weight of the electronic scale, and drawing a liquid absorption amount-time curve. And (5) after a certain time point, the change of the imbibition amount is less than or equal to 0.1g within 600s, namely the imbibition is considered to be finished, and the imbibition time is recorded. The results of the pipetting test are shown in Table 5.
TABLE 5 Performance test results for examples 1-29 and comparative examples 1-3
It can be seen from table 5 that, compared with comparative examples 1 to 3, the cathodes of examples 1 to 11 adopt the cathode of the zebra coating process, the particle size of the middle material is larger than the particle sizes of the materials on both sides, the anode is a common anode, the imbibition rate of the obtained bare cell is obviously increased, only 1250s is needed at the lowest after imbibition is finished, the cycle life of the obtained lithium ion battery is greatly prolonged, and when the capacity is attenuated to 80%, the maximum cycle number can be up to 2620 times.
In embodiments 12 to 19, the conductive layer or the functional material layer is added on the basis of embodiments 1 to 11, so that the liquid absorption rate is obviously increased, 1180s is required at the minimum after the liquid absorption is finished, and the maximum cycle time can be 2860 times when the capacity is attenuated to 80%.
In the embodiments 20 and 21, the conductive layer and the functional material layer are added on the basis of the embodiments 1 to 11, so that the liquid absorption rate is obviously increased, the minimum time is 1190s after the liquid absorption is finished, and the maximum cycle number can be 2680 times when the capacity is attenuated to 80%.
In the embodiments 22 to 26, the anodes are anodes using a zebra coating process, the particle size of the middle material is larger than the particle sizes of the materials on both sides, the cathode is a common cathode, the imbibition rate of the obtained bare cell is also significantly increased, only 1250s is needed after imbibition is completed, the cycle life of the obtained lithium ion battery is greatly prolonged, and when the capacity is attenuated to 80%, the maximum cycle time can be up to 2720 times.
The cathode of example 27 was the cathode of the zebra coating process of example 1 and the anode was the anode of the zebra coating process of example 22. When the imbibition is finished, the imbibition time of the naked electric core only needs 1260s, and when the capacity is attenuated to 80%, the cycle time of the lithium ion battery can reach 2590 times at most.
The cathode of example 28 was the cathode of the zebra coating process of example 2 and the anode was the anode of the zebra coating process of example 23. When the imbibition is finished, the imbibition time of the naked electric core only needs 1240s, and when the capacity is attenuated to 80%, the cycle time of the lithium ion battery can reach 2670 times at most.
The cathode of example 29 was the cathode of the zebra coating process of example 3 and the anode was the anode of the zebra coating process of example 24. When the imbibition is finished, the imbibition time of the naked electric core only needs 1190s, and when the capacity is attenuated to 80%, the cycle time of the lithium ion battery can reach 2720 times at most.
In summary, this is because at least one of the electrode sheets (cathode sheet and/or anode sheet) in embodiments 1 to 29 adopts a zebra coating structure, and a material with a larger particle size is arranged in the middle, and compared with a material with a smaller particle size, because the gaps between the materials with a larger particle size are larger, the number of pores is larger, the specific surface area is lower, the liquid absorption rate and the liquid retention capacity of the middle region are improved, and the side reaction of the middle region is reduced, so that the long-term cycle life of the battery is significantly prolonged.
Compared with the prior art, the lithium ion battery and the pole piece thereof have the following technical effects:
1) active materials with smaller particle sizes are coated in the two side areas of the pole piece, and active materials with larger particle sizes are coated in the middle area, so that the gap between large particles is larger, more pore channels are provided, the infiltration rate of electrolyte of the pole piece can be improved, and the quick liquid absorption of a battery is facilitated;
2) aiming at the characteristic that the temperature of the battery is high in the middle and low on two sides, the active material with larger particle size is coated in the middle area, and the large-particle matter has lower specific surface area and fewer side reactions, so that the long-term cycle performance of the battery is facilitated;
3) the thermal stability and the long-term stability of the pole piece are improved, and the manufacturing efficiency and the safety performance of the battery are improved.
The present invention can be modified and adapted appropriately from the above-described embodiments, according to the principles described above. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims 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 (12)
1. The utility model provides a lithium ion battery pole piece, includes the mass flow body and forms the diaphragm on the mass flow body, the diaphragm contains active material layer, its characterized in that, active material layer is including first active material layer and the second active material layer that is located both sides to and be located the third active material layer in the middle of being located, the particle diameter of material is less than the particle diameter of material in the third active material layer in first active material layer and the second active material layer, first active material layer accounts for 1/5 ~ 3/8 of diaphragm width, the second active material layer accounts for 1/5 ~ 3/8 of diaphragm width, the third active material layer accounts for 1/4 ~ 3/5 of diaphragm width.
2. The pole piece of claim 1, wherein the first active material layer is 1/4-1/3 of the width of the membrane, the second active material layer is 1/4-1/3 of the width of the membrane, and the third active material layer is 1/3-1/2 of the width of the membrane.
3. The lithium ion battery pole piece of claim 1, wherein the first active material layer comprises 1/4 of the width of the membrane sheet, the second active material layer comprises 1/4 of the width of the membrane sheet, and the third active material layer comprises 1/2 of the width of the membrane sheet.
4. The lithium ion battery pole piece of claim 1, wherein the first active material layer comprises 1/3 of the width of the membrane sheet, the second active material layer comprises 1/3 of the width of the membrane sheet, and the third active material layer comprises 1/3 of the width of the membrane sheet.
5. The lithium ion battery pole piece of claim 1, wherein the difference between the particle size of the material in the third active material layer and the particle size of the material in the first and second active material layers D50 is more than 20%.
6. The lithium ion battery pole piece of claim 1, wherein the thickness of the lithium ion battery pole piece is 20 μm to 200 μm.
7. The lithium ion battery pole piece of claim 1, wherein the first, second and third active material layers are in a rectangular, square or parallelogram configuration.
8. The lithium ion battery pole piece of claim 1, wherein the membrane further comprises a conductive layer or a functional material layer, wherein the thickness of the conductive layer is not more than 10 μm, and the thickness of the functional material layer is not more than 10 μm.
9. The lithium ion battery pole piece of claim 1, wherein the membrane further comprises a conductive layer formed on the surface of the current collector and a functional material layer formed on the surface of the conductive layer; the thickness of the conductive layer is not more than 10 μm, and the thickness of the functional material layer is not more than 10 μm.
10. The lithium ion battery pole piece of claim 1, wherein the membrane further comprises a conductive layer and a functional material layer, the functional material layer is formed on the surface of the current collector, and the conductive layer is formed on the surface of the functional material layer; the thickness of the conductive layer is not more than 10 μm, and the thickness of the functional material layer is not more than 10 μm.
11. The lithium ion battery pole piece of any one of claims 8 to 10, wherein the conductive layer comprises a conductive agent selected from at least one of conductive carbon, conductive graphite, conductive ink, ketjen black, carbon nanotubes, conductive carbon fibers, acetylene black; the functional material layer is one of an inorganic coating, an organic/inorganic composite coating and an organic coating.
12. A lithium ion battery comprising a cathode sheet, an anode sheet, a separator film spaced between the cathode sheet and the anode sheet, and an electrolyte, wherein at least one of the cathode sheet and the anode sheet is the lithium ion battery electrode sheet of any one of claims 1 to 11.
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| CN113130841A (en) * | 2019-12-31 | 2021-07-16 | 荣盛盟固利新能源科技有限公司 | Lithium ion battery pole piece, preparation method thereof and lithium ion battery |
| CN113258031B (en) * | 2020-02-11 | 2022-11-18 | 宁德新能源科技有限公司 | Battery with a battery cell |
| CN111276757B (en) * | 2020-02-19 | 2021-01-05 | 苏州睿邦工业设计有限公司 | Preparation method of power type lithium ion battery |
| CN114597336A (en) * | 2022-03-23 | 2022-06-07 | 珠海冠宇电池股份有限公司 | Negative plate and battery |
| CN115832197A (en) * | 2022-11-10 | 2023-03-21 | 宁德时代新能源科技股份有限公司 | Composite electrode and preparation method thereof, battery and electric equipment |
| CN117133860A (en) * | 2023-10-27 | 2023-11-28 | 宁德时代新能源科技股份有限公司 | Positive plate, battery monomer, battery and power utilization device |
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| CN105680019A (en) * | 2016-03-16 | 2016-06-15 | 江苏乐能电池股份有限公司 | Preparation method of high-rate ternary material |
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