CN114614200A - Electrochemical device and electric equipment - Google Patents
Electrochemical device and electric equipment Download PDFInfo
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- CN114614200A CN114614200A CN202210346673.7A CN202210346673A CN114614200A CN 114614200 A CN114614200 A CN 114614200A CN 202210346673 A CN202210346673 A CN 202210346673A CN 114614200 A CN114614200 A CN 114614200A
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Images
Classifications
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
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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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
- H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
- H01M50/491—Porosity
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- 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
Abstract
The embodiment of the application relates to the technical field of energy storage power supplies, and discloses an electrochemical device and electric equipment, wherein the electrochemical device comprises a positive plate, a negative plate and a partition plate, the partition plate is positioned between the positive plate and the negative plate, the partition plate comprises a first porous layer and a second porous layer, the average pore size of the first porous layer is smaller than that of the second porous layer, the positive plate is arranged on the surface of the first porous layer, the negative plate is arranged on the surface of the second porous layer, the porous layer which is different from the porous layer which is attached to the positive plate and the porous layer which are different from the porous layer which are attached to the negative plate are arranged on the partition plate, so that the reasonable distribution of the electrolyte on the interface between the positive plate and the partition plate and the reasonable distribution of the electrolyte between the negative plate and the partition plate can be realized, the ion transmission capability of the interface between the positive plate and the partition plate and the ion transmission capability of the interface between the negative plate and the partition plate are balanced, the working internal resistance of the electrochemical device is reduced, the charging polarization of the electrochemical device is favorably balanced, and the discharge capacity of the electrochemical device is improved.
Description
Technical Field
The embodiment of the application relates to the technical field of energy storage power supplies, in particular to an electrochemical device and electric equipment.
Background
With the rapid development of lithium ion batteries, the lithium ion batteries have been widely applied to the fields of electronic communication, energy storage, power supplies and the like. The diaphragm for the lithium ion battery is one of key inner layer components of the battery, is positioned between a positive electrode and a negative electrode, prevents short circuit caused by contact of the positive electrode and the negative electrode, allows electrolyte ions to pass through, determines the interface structure, internal resistance and the like of the battery, directly influences the capacity, circulation, charge and discharge, safety and other performances of the lithium ion battery and the consistency of the performances, and the battery diaphragm with excellent performance plays an important role in improving the comprehensive performance of the battery.
In the process of implementing the embodiment of the present application, the inventors found that: at present, the traditional battery separator has the contradiction between porosity, air permeability and thermal shrinkage performance, namely, when the porosity is high and the air permeability is low, the thermal shrinkage performance of the battery separator is poor, and when the thermal shrinkage performance of the battery separator is enhanced, the porosity is lowered, the air permeability is raised, and the service characteristics and the safety performance of the battery are influenced.
Disclosure of Invention
The technical problem that this application embodiment mainly solved provides an electrochemical device and consumer, can have macropore aperture and aperture concurrently for the diaphragm can have high porosity, and the thermal contraction performance is good simultaneously.
In order to solve the above technical problem, one technical solution adopted in the embodiments of the present application is: provided is an electrochemical device comprising a positive electrode sheet, a negative electrode sheet, and a separator, the separator being located between the positive electrode sheet and the negative electrode sheet, the separator comprising a first porous layer and a second porous layer, the positive electrode sheet being disposed on the surface of the first porous layer, the negative electrode sheet being disposed on the surface of the second porous layer, the first porous layer having an average pore size of A1 μm, the second porous layer having an average pore size of A2 μm, the A1 and the A2 satisfying: a1 < A2.
In some embodiments, the average pore size a1 of the first porous layer satisfies: a1 is more than or equal to 0.01 mu m and less than or equal to 0.05 mu m.
In some embodiments, the average pore size a2 of the second porous layer satisfies: a2 is more than 0.05 μm and less than or equal to 1 μm.
In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector; the surface of the negative electrode active material layer is vertical to the direction of the negative electrode current collector, and the cross-sectional porosity of 10 mu m of the surface of the negative electrode active material layer is N10，2≤N10/A2≤5。
In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector; the surface of the positive electrode active material layer is vertical to the direction of the positive electrode current collector, and the cross-section porosity of 10 mu m of the surface of the positive electrode active material layer is P10，2≤P10/A1≤10。
In some embodiments, the electrochemical device satisfies: 0.3 is less than or equal to (N)10/A2)/(P10/A1)≤0.75。
In some embodiments, the electrochemical device satisfies: n is more than or equal to 20 percent10≤30％；10％≤P10≤20％。
In some embodiments, the adhesion force F1 between the first porous layer and the positive electrode sheet, and the adhesion force F2 between the second porous layer and the negative electrode sheet satisfy: f1 < F2.
In some embodiments, the contact angle of the first porous layer is θ 1, the contact angle of the second porous layer is θ 2, and θ 1 and θ 2 satisfy: theta 1 is more than or equal to theta 2, and theta 1 is less than or equal to 10 degrees.
In order to solve the above technical problem, another technical solution adopted in the embodiment of the present application is: there is provided a powered device comprising the electrochemical device described above, the electrochemical device being configured to provide electrical energy to the powered device.
The electrochemical device of the embodiment of the application has the beneficial effects that: the electrochemical device comprises a positive plate, a negative plate and a partition plate, wherein the partition plate is positioned between the positive plate and the negative plate, the partition plate comprises a first porous layer and a second porous layer, the average pore diameter of the first porous layer is smaller than that of the second porous layer, the positive plate is attached to the surface of the first porous layer, the negative plate is attached to the surface of the second porous layer, the porous layers with different average pore diameters are arranged on the partition plate, and are respectively attached to the positive plate and the negative plate.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.
Fig. 1 is a cross-sectional view from a perspective of an electrochemical device according to an embodiment of the present application.
Fig. 2 is an enlarged view of a portion M of an electrochemical device according to an embodiment of the present disclosure.
Fig. 3 is an enlarged view of a portion M of an electrochemical device according to another embodiment of the present application.
Fig. 4 is a cross-sectional view from a perspective of an electrochemical device according to yet another embodiment of the present application.
The reference numbers in the detailed description are as follows:
| 100 | |
13 | |
| 10 | Electrode assembly | 131 | A first |
| 11 | Positive plate | 132 | A |
| 111 | Positive current collector | 133 | A second |
| 112 | Positive electrode |
134 | |
| 12 | |
135 | |
| 121 | Negative |
20 | |
| 122 | Negative electrode |
30 | Electrolyte solution |
Detailed Description
In order to facilitate an understanding of the present application, the present application is described in more detail below with reference to the accompanying drawings and specific embodiments. It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may be present. As used herein, the terms "upper," "lower," "inner," "outer," "vertical," "horizontal," and the like are used in an orientation or positional relationship that is based on the orientation or positional relationship as shown in the figures, which is for ease of description and simplicity of description only, and does not indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and therefore should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In addition, the technical features mentioned in the different embodiments of the present application described below may be combined with each other as long as they do not conflict with each other.
Referring to fig. 1 and 2, an electrochemical device 100 includes an electrode assembly 10, a package case 20, and an electrolyte 30. The package case 20 is provided with a receiving cavity in which the electrode assembly 10 and the electrolyte 30 are received and the electrode assembly 10 is soaked in the electrolyte 30. The electrolyte 30 provides an ion transport environment for electrochemical reactions to occur in the electrode assembly 10.
It is worth mentioning that: the electrochemical device 100 may be a pouch cell, i.e. the package 20 is made of a flexible material, such as: the aluminum-plastic film, the electrochemical device 100 can also be a hard-shell battery, and the package 20 is made of a hard material, such as: a metal.
The positive electrode active material layer 112 and the negative electrode active material layer 122 are mainly used for participating in electrochemical reaction, and if the porosity of the positive electrode active material layer 112 and the porosity of the negative electrode active material layer 122 are too small, wettability of the electrolyte 30 on the surface of the positive electrode active material layer 112 and the surface of the negative electrode active material layer 122 is affected, a lithium ion transmission channel is reduced, reaction between the positive electrode sheet 11 and the negative electrode sheet 12 is hindered, and reaction efficiency is reduced; when the porosity of the positive electrode active material layer 112 and the porosity of the negative electrode active material layer 122 are too large, the content of the positive electrode active material and the content of the negative electrode active material are reduced, and the capacity of the electrochemical device 100 is reduced, and therefore, the porosity P of the positive electrode active material layer 112 is reduced10And the porosity N of the anode active material layer 12210Needs to be set within a reasonable range, which is beneficial to improving the wettability of the electrolyte 30 on the positive plate 11 and the negative plate 12, improving the probability of smooth lithium ion extraction, and improving the ion transmission performance of the pole pieces.
In some embodiments, referring to fig. 3, the separator 13 may include a first porous layer 131, a second porous layer 133, and a substrate layer 135, wherein the first porous layer 131 and the second porous layer 133 are respectively disposed on two sides of the substrate layer 135. It is understood that, in the present application, the first porous layer 131 is disposed on the surface of the positive electrode sheet 11, and the second porous layer 133 is disposed on the surface of the negative electrode sheet 12, so that the resistance can be reduced, the cycle performance of the electrochemical device can be improved, and the discharge capacity can be increased.
The cross-sectional porosity P of the positive electrode sheet 11 was defined by a surface thickness of the positive electrode active material layer 112 of 10 μm10The ratio to the average pore diameter a1 of first porous layer 131 of separator 13 is a first interface ratio that satisfies: 2 is less than or equal to P10the/A1 is less than or equal to 10. The cross-sectional porosity N of 10 μm in the surface thickness of the negative electrode active material layer 122 of the negative electrode sheet 12 was defined10Ratio to average pore diameter a2 of second porous layer 133 of separator 13 a second interfacial ratio which satisfies: 2 is less than or equal to N10the/A2 is less than or equal to 5. The first interface ratio characterizes the surface of the positive electrode active material layer 112 and the first porous layer 131, the ion transmission between the positive plate 11 and the separator 13 is easily affected due to the overlarge or the undersize first interface ratio; the second interface ratio represents the degree of interface matching between the surface of the negative electrode active material layer 122 and the surface of the second porous layer 133, and the second interface ratio is too large or too small, which easily causes the influence on the ion transmission between the negative electrode sheet 12 and the separator 13, thereby influencing the chemical reaction between the positive electrode sheet 11 and the negative electrode sheet 12, and therefore, the first interface ratio and the second interface ratio should be within a reasonable range.
Defining the ratio of the second interface ratio to the first interface ratio as a third interface ratio, i.e., (N)10/A2)/(P10A1), and the third interface ratio is characterized by the transport efficiency of ions in the system formed by the positive electrode interface, the separator 13 and the negative electrode interface in the electrochemical device 100, and when the second interface ratio is smaller than the first interface ratio, the third interface ratio satisfies: 0.2 < (N)10/A2)/(P10A1) < 1, preferably 0.3. ltoreq. (N)10/A2)/(P10/a1) is less than or equal to 0.75, and at this time, the first porous layer 131 with the smaller average pore size synergistically acts to balance ion transport between the positive electrode sheet 11 and the negative electrode sheet 12, reduce impedance, and improve cycle performance of the electrochemical device 100.
The first porous layer 131 comprises a first polymer 132, the first polymer 132 comprising at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, or a copolymer of vinylidene fluoride and an acrylate; the second porous layer 133 includes a second polymer 134, and the second polymer 134 includes at least one of an acrylate-type polymer, a styrene-acrylate copolymer, polyvinylidene fluoride, a vinylidene fluoride-hexafluoropropylene copolymer, an acrylonitrile-acrylate copolymer, a vinyl chloride-acrylate copolymer, or a butadiene-styrene copolymer.
The adhesion force F1 between the first porous layer 131 and the positive electrode sheet 11, and the adhesion force F2 between the second porous layer 133 and the negative electrode sheet 12 satisfy: f1 < F2. During the cycle, the cycle tension of the negative electrode sheet 12 is large, and therefore the interfacial deformation rate of the negative electrode active material layer 122 of the negative electrode sheet 12 is larger than that of the positive electrode active material layer 112 of the positive electrode sheet 11, and in order to reduce the influence of the negative electrode interfacial deformation on the electrical properties, the adhesion between the second porous layer 133 and the negative electrode active material layer 122 is larger than that between the first porous layer 131 and the positive electrode active material layer 112. The interface adhesive force between the negative electrode plate 12 and the separator 13 is improved, and the ion transmission performance between the positive electrode plate 11 and the negative electrode plate 12 is not affected, so that the impedance of the electrochemical device 100 is reduced, and the charge and discharge performance of the electrochemical device 100 is improved.
The contact angle of the first porous layer 131 is θ 1, the contact angle of the second porous layer 133 is θ 2, and θ 1 and θ 2 satisfy: theta 1 is more than or equal to theta 2, and theta 1 is less than or equal to 10 degrees. The contact angle of the surface layer of separator 13 reflects the affinity of separator 13 with electrolyte 30 in electrochemical device 100. Specifically, in the present application, second porous layer 133 on the negative electrode sheet 12 side is designed to have a larger average pore diameter, and therefore, in order to improve the interfacial performance of separator 13 and increase the amount of electrolyte 30 held at the interface on the negative electrode sheet 12 side, it is necessary to reduce contact angle θ 2 of second porous layer 131. Therefore, the contact angle θ 2 of the second porous layer 133 is smaller than the contact angle θ 1 of the first porous layer 131, and preferably, the contact angle θ 1 of the first porous layer 131 and the contact angle θ 2 of the second porous layer 133 are 10 degrees or less. Because the main limitation of the quick charge performance of the battery is on the side of the negative plate 12, when the wettability of the electrolyte 30 on the side of the negative plate 12 is better than that on the side of the positive plate 11, the impedance of the electrochemical device 100 is favorably reduced, and the rate capability is improved; if contact angle θ 1 of first porous layer 131 and contact angle θ 2 of second porous layer 133 are too large, wetting of the partial regions of positive electrode sheet 11 and negative electrode sheet 12 is likely to be poor, and lithium deposition may occur, which may affect the safety of electrochemical device 100.
In some embodiments, referring to fig. 4, the electrode assembly 10 may also be a lamination stack in which the positive electrode tab 11, the separator 13, and the negative electrode tab 12 are sequentially stacked.
In addition, in order to facilitate the reader to understand the technical effects brought by the technical solution of the present application more easily, a comparative test is also performed in the embodiments of the present application, wherein both the embodiments of the present application and the comparative examples are lithium ion batteries manufactured by housing the electrode assembly 10 in the package case 20 and filling the electrolyte 30 and then packaging the battery, and of course, the embodiments of the present application are not limited thereto, and the specific test procedures are as follows:
comparative example 1
(1) Preparing a negative plate: mixing a negative electrode active material graphite, conductive carbon black (Super P) and Styrene Butadiene Rubber (SBR) according to a weight ratio of 96:1.5:2.5, adding deionized water, preparing into slurry with a solid content of 0.7, uniformly stirring, uniformly coating the slurry on one surface of a negative electrode current collector copper foil, drying at 110 ℃ to obtain a negative electrode active material layer, forming another negative electrode active material layer on the other surface of the negative electrode current collector by adopting the same process, further cutting and welding a tab to obtain a negative electrode sheet.
(2) Preparing a positive plate: mixing positive active materials of lithium cobaltate (LiCoO2), conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5, adding N-methylpyrrolidone (NMP) as a solvent, preparing into slurry with the solid content of 0.75, uniformly stirring, uniformly coating the slurry on a positive current collector aluminum foil, and drying at 90 ℃ to obtain a positive active material layer. And then another positive active material layer is formed on the other surface of the positive current collector using the same process. And further, cutting and welding the tabs to obtain the positive plate.
(3) Preparing an electrolyte: in a dry argon atmosphere, organic solvents of Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC) and diethyl carbonate (DEC) are mixed according to a mass ratio of 30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF6) is added to dissolve and mix uniformly, so that an electrolyte with a concentration of 1.15mol/L of LiPF6 is obtained.
(4) Preparing a separator: a 10 μm Polyethylene (PE) based film was used directly.
(5) Preparing a lithium ion battery: and (3) relatively stacking the obtained positive plate, the negative plate and a 10-micron Polyethylene (PE) base film, winding, placing in an outer packaging foil, and carrying out processes such as liquid injection and packaging to obtain the lithium ion battery.
Comparative example 2
The positive electrode sheet, the negative electrode sheet and the electrolyte were prepared in the same manner as in comparative example 1.
(1) Preparing a separator: the 10 μm fiber membrane was used directly.
(2) Preparing a lithium ion battery: and (3) relatively stacking and winding the positive plate, the negative plate and the 10-micron fiber film, placing the positive plate, the negative plate and the fiber film into an outer packaging foil, and carrying out processes such as liquid injection, packaging and the like to obtain the lithium ion battery.
Comparative example 3
The positive electrode sheet, the negative electrode sheet and the electrolyte were prepared in the same manner as in comparative example 1.
(1) Preparing a separator: a10 μm fiber film was bonded to a 5 μm Polyethylene (PE) substrate, and hot-pressed with a roller gap of 10 μm adjusted.
(2) Preparing a lithium ion battery: and (3) relatively stacking and winding the positive plate, the negative plate and the separator, placing the positive plate, the negative plate and the separator into an outer packaging foil, and performing processes such as liquid injection, packaging and the like to obtain the lithium ion battery, wherein the Polyethylene (PE) layer of the separator is attached to the negative plate.
Example 1-1
(1) Preparing a negative plate: mixing a negative electrode active material graphite, conductive carbon black (Super P) and Styrene Butadiene Rubber (SBR) according to a weight ratio of 96:1.5:2.5, adding deionized water, preparing into slurry with a solid content of 0.7, uniformly stirring, uniformly coating the slurry on one surface of a negative electrode current collector copper foil, drying at 110 ℃ to obtain a negative electrode active material layer, forming another negative electrode active material layer on the other surface of the negative electrode current collector by adopting the same process, rolling by using a pressure of 6T, further, cutting pieces and welding tabs to obtain a negative electrode piece.
(2) Preparing a positive plate: the positive electrode active material lithium cobaltate (LiCoO)2) Mixing conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to the weight ratio of 97.5:1.0:1.5, adding N-methylpyrrolidone (NMP) as a solvent, preparing into slurry with the solid content of 0.75, uniformly stirring, uniformly coating the slurry on an aluminum foil of a positive current collector, and drying at the temperature of 90 ℃ to obtain a positive active material layer. Then, another positive electrode active material layer was formed on the other surface of the positive electrode current collector by the same process, and was rolled using a 6T pressure, and furtherAnd then, cutting the piece and welding the tab to obtain the positive plate.
(3) Preparing an electrolyte: in a dry argon atmosphere, organic solvents of Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of 30:50:20, and then lithium salt of lithium hexafluorophosphate (LiPF) was added6) Dissolving and mixing evenly to obtain LiPF6Electrolyte with the concentration of 1.15 mol/L.
(4) Preparing a separator: rolling a 10 μm polyvinylidene fluoride (PVDF) fiber film with a roll gap of 2.5 μm to obtain a film A; rolling a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film with a roll gap of 5 μm to obtain a film B; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, where film B was attached to the negative electrode sheet.
(5) Preparing a lithium ion battery: and (3) relatively stacking and winding the positive plate, the negative plate and the partition plate, placing the positive plate, the negative plate and the partition plate into an outer packaging foil, and carrying out processes such as liquid injection, packaging and the like to obtain the lithium ion battery.
Test method
(1) Method for testing 02C discharge capacity storage rate of lithium ion battery
The lithium ion battery is stood for 5 minutes at 25 ℃, then charged to 4.45V by a current constant current of 0.7C, then charged to 0.05C by a constant voltage of 4.45V, stood for 5 minutes, and then discharged to 3.0V by a constant current of 0.5C, and stood for 5 minutes. And repeating the charging and discharging process, discharging at 0.1C, and recording the 0.1C discharge capacity of the lithium ion battery.
(2) Method for testing Direct Current Resistance (DCR) of lithium ion battery
At 25 ℃, the lithium ion battery was charged to 4.45V at a constant current of 1.5C, then charged to 0.05C at a constant voltage of 4.45V, and left to stand for 30 minutes. The discharge was performed at 0.1C for 10 seconds and the recording voltage was U1, and the discharge was performed at 1C for 360 seconds and the recording voltage was U2. The charging and discharging steps were repeated 5 times. "1C" is a current value at which the capacity of the lithium ion battery is completely discharged within 1 hour.
The dc resistance R of the lithium ion battery at 25 ℃ was calculated by the following formula: r ═ (U2-U1)/(1C-0.1C).
(3) Method for testing average pore diameter of separator
Selecting a test area of 1000 micrometers multiplied by 100 micrometers on the surface of the partition board, counting all pores in the area, distinguishing brightness between the partition board and the pores in an Image, wherein the partition board material is used for higher brightness, the pores are used for darker brightness, then processing the Image by using Image J software, adjusting the diaphragm to be a black back, adjusting the pores to be white, counting the pore diameters of the pores, and calculating to obtain the average pore diameter.
(4) Method for testing section porosity of positive and negative electrode active material layers
The sample preparation process comprises the following steps: cutting the active substance layer to 0.5cm multiplied by 1cm, adhering the cut active substance layer on a silicon wafer carrier with the size of 1cm multiplied by 1.5cm by using a conductive adhesive, and then processing one end of the pole piece by using argon ion polishing (the parameter: the accelerating voltage of 8KV, each sample is 4 hours), wherein the argon ion polishing is to ionize argon gas by using a high-voltage electric field to generate an ionic state, and the generated argon ions bombard the surface of the pole piece at high speed under the action of the accelerating voltage to denude the pole piece layer by layer so as to achieve the polishing effect.
After the sample preparation was completed, it was analyzed by Scanning Electron Microscope (SEM). The scanning electron microscope used in the application is a JSM-6360LV model of JEOL company for analyzing the morphology and structure of a sample.
And (3) testing the porosity of sections of the active material layer with different thicknesses: selecting a test area of 1000μm multiplied by 10μm, counting gaps between all particles in a cross section at the thickness of 0μm to 10μm on the surface of the pole piece, distinguishing brightness between the particles and the gaps in an Image, wherein the particles with higher brightness are the particles, the gaps are the darker particles, processing the Image by using Image J software, adjusting the particles to be black background, adjusting the gaps to be white, and counting the area of the gaps occupying the whole Image to obtain the porosity of the cross section. Surface porosity was counted in the same manner.
(5) Contact angle testing method
At room temperature, 1 μ L of electrolyte (electrolyte refers to the electrolyte formulation provided herein) was dropped onto the surface of the separator, then optical imaging was performed by a CCD (charge coupled device), and the obtained image was fitted to obtain the contact angle of the electrolyte on the surface of the separator.
The positive electrode sheet, the negative electrode sheet, the electrolyte, and the lithium ion battery in the following examples 1-2 to 1-9 were prepared in the same manner as in example 1-1, except that the first porous layer and the second porous layer of the separator had different roll gaps, and the specific parameters and test results were as follows:
TABLE 1
Note: the K value represents the safety performance of the lithium ion battery, and the smaller the K value is, the better the safety performance of the lithium ion battery is.
According to the data result, it can be obtained that:
(1) by controlling the average pore diameter of the first porous layer to be smaller than that of the second porous layer, the electrolyte between the two sides of the partition plate and the positive plate and between the two sides of the partition plate and the negative plate can be reasonably distributed, the interface of the positive plate and the partition plate and the ion transmission capacity of the interface of the negative plate and the partition plate are balanced, the working internal resistance of the lithium battery can be reduced, the charging polarization of the lithium battery can be balanced, and the discharge capacity of the lithium battery can be improved.
(2) On the premise that the average pore diameter of the first porous layer is smaller than that of the second porous layer, increasing the average pore diameter of the second porous layer can increase the discharge capacity of the lithium battery and reduce the working internal resistance of the lithium battery, but can reduce the safety performance of the lithium battery.
(3) On the premise that the average pore diameter of the first porous layer is smaller than that of the second porous layer and the average pore diameter of the second porous layer is not changed, increasing the average pore diameter of the first porous layer can also increase the discharge capacity of the lithium battery and reduce the working internal resistance of the lithium battery, but can reduce the safety performance of the lithium battery.
Example 2-1
(1) Preparing a negative plate: mixing a negative electrode active material graphite, conductive carbon black (Super P) and Styrene Butadiene Rubber (SBR) according to a weight ratio of 96:1.5:2.5, adding deionized water, preparing into slurry with a solid content of 0.7, uniformly stirring, uniformly coating the slurry on one surface of a negative electrode current collector copper foil, drying at 110 ℃ to obtain a negative electrode active material layer, forming another negative electrode active material layer on the other surface of the negative electrode current collector by adopting the same process, rolling by using a pressure of 6T, further, cutting pieces and welding tabs to obtain a negative electrode piece.
(2) Preparing a positive plate: the positive electrode active material lithium cobaltate (LiCoO)2) Mixing conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to the weight ratio of 97.5:1.0:1.5, adding N-methylpyrrolidone (NMP) as a solvent, preparing into slurry with the solid content of 0.75, uniformly stirring, uniformly coating the slurry on an aluminum foil of a positive current collector, and drying at the temperature of 90 ℃ to obtain a positive active material layer. And then, forming another positive active material layer on the other surface of the positive current collector by adopting the same process, rolling by using the pressure of 6T, and further, cutting pieces and welding lugs to obtain the positive plate.
(3) Preparing an electrolyte: in a dry argon atmosphere, organic solvents of Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of 30:50:20, and then lithium salt of lithium hexafluorophosphate (LiPF) was added6) Dissolving and mixing evenly to obtain LiPF6Electrolyte with the concentration of 1.15 mol/L.
(4) Preparing a separator: rolling a 10 μm polyvinylidene fluoride (PVDF) fiber film with a roll gap of 2.5 μm to obtain a film A; a10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was rolled with a roll gap of 4.5 μm to prepare a film B; film a and film B were stacked and roll compounded using a 7 μm roll gap, in which film B was attached to the negative electrode sheet.
(5) Preparing a lithium ion battery: and (3) relatively stacking and winding the positive plate, the negative plate and the partition plate, placing the positive plate, the negative plate and the partition plate into an outer packaging foil, and carrying out processes such as liquid injection, packaging and the like to obtain the lithium ion battery.
The positive electrode sheet, negative electrode sheet, electrolyte and lithium ion battery in the following examples 2-2 to 2-12 and comparative example 2-1 were prepared in the same manner as in example 1-1, except that the rolling pressure of the positive electrode sheet and negative electrode sheet and the preparation of the separator were different, specifically as follows:
TABLE 2
According to the data result, it can be obtained that:
(1) by controlling the porosity P10 of the positive electrode active material layer and the average pore diameter A1 of the first porous layer, the porosity N10 of the negative electrode active material layer and the average pore diameter A2 of the second porous layer within a proper range, and satisfying that the porosity P10 of the positive electrode active material layer is smaller than the porosity N10 of the negative electrode active material layer, and the average pore diameter A1 of the first porous layer is smaller than the average pore diameter A2 of the second porous layer, the capacity of the lithium ion battery can be made higher, the working impedance of the lithium ion battery can be reduced, and the rate capability of the lithium ion battery can be improved.
Example 3-1
(1) Preparing a negative plate: mixing a negative electrode active material graphite, conductive carbon black (Super P) and Styrene Butadiene Rubber (SBR) according to a weight ratio of 96:1.5:2.5, adding deionized water, preparing into slurry with a solid content of 0.7, uniformly stirring, uniformly coating the slurry on one surface of a negative electrode current collector copper foil, drying at 110 ℃ to obtain a negative electrode active material layer, forming another negative electrode active material layer on the other surface of the negative electrode current collector by adopting the same process, rolling by using a pressure of 6T, further, cutting pieces and welding tabs to obtain a negative electrode piece.
(2) Preparing a positive plate: mixing a positive electrode active material lithium cobaltate (LiCoO2), conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5, adding N-methylpyrrolidone (NMP) as a solvent, preparing into slurry with a solid content of 0.75, uniformly stirring, uniformly coating the slurry on a positive electrode current collector aluminum foil, and drying at 90 ℃ to obtain a positive electrode active material layer. And then, forming another positive active material layer on the other surface of the positive current collector by adopting the same process, rolling by using the pressure of 6T, and further, cutting pieces and welding lugs to obtain the positive plate.
(3) Preparing an electrolyte: in a dry argon atmosphere, organic solvents of Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC) and diethyl carbonate (DEC) are mixed according to a mass ratio of 30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF6) is added to dissolve and mix uniformly, so that an electrolyte with a concentration of 1.15mol/L of LiPF6 is obtained.
(4) Preparing a separator: rolling a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 2.5 μm to obtain a film A; rolling a 10 μm Polyethylene (PE) fiber film with a roll gap of 5 μm to obtain a film B; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, where film B was attached to the negative electrode sheet.
(5) Preparing a lithium ion battery: and (3) relatively stacking and winding the positive plate, the negative plate and the partition plate, placing the positive plate, the negative plate and the partition plate into an outer packaging foil, and carrying out processes such as liquid injection, packaging and the like to obtain the lithium ion battery.
The positive electrode sheet, the negative electrode sheet, the electrolyte and the lithium ion battery of examples 3-2 to 3-10 and comparative examples 3-1 and 3-2 were prepared in the same manner as in example 3-1, except that the rolling pressure of the positive electrode sheet, the rolling pressure of the negative electrode sheet and the preparation of the separator were different as follows:
examples 3 to 2
(1) The positive plate was rolled with a pressure of 6T, and the negative plate was rolled with a pressure of 6T.
(2) Preparing a separator: rolling a 10 μm Polyethylene (PE) fiber film with a roll gap of 2.5 μm to obtain a film A; rolling a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 5 μm to obtain a film B; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, where film B was attached to the negative electrode sheet.
Examples 3 to 3
(1) The positive plate was rolled with a pressure of 6T, and the negative plate was rolled with a pressure of 6T.
(2) Preparing a separator: a10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was rolled with a roll gap of 2.5 μm to prepare a film A; rolling a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 5 μm to obtain a film B; film a and film B, to which the negative electrode sheet was attached, were stacked and roll-compounded using a 7.5 μm roll gap.
Examples 3 to 4
(1) The positive plate was rolled with a pressure of 6T, and the negative plate was rolled with a pressure of 6T.
(2) Preparing a separator: rolling a 10 μm Polyethylene (PE) fiber film with a roll gap of 2.5 μm to obtain a film A; rolling a 10 μm Polyethylene (PE) fiber film with a roll gap of 5 μm to obtain a film B; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, where film B was attached to the negative electrode sheet.
Examples 3 to 5
(1) The positive plate was rolled with a pressure of 6T, and the negative plate was rolled with a pressure of 4T.
(2) Preparing a separator: rolling a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 2.5 μm to obtain a film A; rolling a 10 μm Polyethylene (PE) fiber film with a roll gap of 4.5 μm to obtain a film B; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, where film B was attached to the negative electrode sheet.
Examples 3 to 6
(1) The positive plate was rolled with a pressure of 6T, and the negative plate was rolled with a pressure of 8T.
(2) Preparing a separator: rolling a 10 μm Polyethylene (PE) fiber film with a roll gap of 2.5 μm to obtain a film A; rolling a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 8 μm to obtain a film B; film a and film B were stacked and roll compounded using a 10.5 μm roll gap, where film B was attached to the negative electrode sheet.
Examples 3 to 7
(1) The positive plate was rolled with a pressure of 6T, and the negative plate was rolled with a pressure of 8T.
(2) Preparing a separator: a10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was rolled with a roll gap of 2.5 μm to prepare a film A; rolling a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 4.5 μm to obtain a film B; film a and film B were stacked and roll compounded using a 7 μm roll gap, in which film B was attached to the negative electrode sheet.
Examples 3 to 8
(1) The positive plate was rolled using a pressure of 6T, and the negative plate was rolled using a pressure of 8T.
(2) Preparing a separator: rolling a 10 μm Polyethylene (PE) fiber film with a roll gap of 2.5 μm to obtain a film A; rolling a 10 μm Polyethylene (PE) fiber film with a roll gap of 8 μm to obtain a film B; film a and film B were stacked and roll compounded using a 10.5 μm roll gap, where film B was attached to the negative electrode sheet.
Examples 3 to 9
(1) The positive plate was rolled with a pressure of 7.5T and the negative plate was rolled with a pressure of 8T.
(2) Preparing a separator: rolling a 10 μm Polyethylene (PE) fiber film with a roll gap of 1.5 μm to obtain a film A; rolling a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 8 μm to obtain a film B; film a and film B were stacked and roll compounded using a 9.5 μm roll gap, where film B was attached to the negative electrode sheet.
Examples 3 to 10
(1) The positive plate was rolled with a pressure of 7.5T and the negative plate was rolled with a pressure of 8T.
(2) Preparing a separator: rolling a 10 μm Polyethylene (PE) fiber film with a roll gap of 1.5 μm to obtain a film A; rolling a 10 μm Polyethylene (PE) fiber film with a roll gap of 8 μm to obtain a film B; film a and film B were stacked and roll compounded using a 9.5 μm roll gap, where film B was attached to the negative electrode sheet.
Comparative example 3-1
(1) The positive plate was rolled with a pressure of 8T, and the negative plate was rolled with a pressure of 4T.
(2) Preparing a separator: rolling a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 4.5 μm to obtain a film A; rolling a 10 μm Polyethylene (PE) fiber film with a roll gap of 4.5 μm to obtain a film B; film a and film B were stacked and roll compounded using a 9 μm roll gap, in which film B was attached to the negative electrode sheet.
Comparative examples 3 to 2
(1) The positive plate was rolled with a pressure of 8T, and the negative plate was rolled with a pressure of 4T.
(2) Preparing a separator: a10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was rolled with a roll gap of 4.5 μm to prepare a film A; rolling a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 4.5 μm to obtain a film B; film a and film B were stacked and roll compounded using a 9 μm roll gap, in which film B was attached to the negative electrode sheet.
TABLE 3
According to the data result, the following data can be obtained:
(1) the contact angle of the second porous layer of the separator is smaller than that of the first porous layer, so that the wettability of the electrolyte on the surface of the second porous layer is superior to that of the electrolyte on the surface of the first porous layer, the working impedance of the lithium ion battery is favorably reduced, and the rate capability of the lithium ion battery is improved.
Example 4-1
(1) Preparing a negative plate: mixing a negative electrode active material graphite, conductive carbon black (Super P) and Styrene Butadiene Rubber (SBR) according to a weight ratio of 96:1.5:2.5, adding deionized water, preparing into slurry with a solid content of 0.7, uniformly stirring, uniformly coating the slurry on one surface of a negative electrode current collector copper foil, drying at 110 ℃ to obtain a negative electrode active material layer, forming another negative electrode active material layer on the other surface of the negative electrode current collector by adopting the same process, rolling by using a pressure of 6T, further, cutting pieces and welding tabs to obtain a negative electrode piece.
(2) Preparing a positive plate: the positive electrode active material lithium cobaltate (LiCoO)2) Mixing conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to the weight ratio of 97.5:1.0:1.5, adding N-methylpyrrolidone (NMP) as a solvent, preparing into slurry with the solid content of 0.75, uniformly stirring, uniformly coating the slurry on an aluminum foil of a positive current collector, and drying at the temperature of 90 ℃ to obtain a positive active material layer. And then, forming another positive active material layer on the other surface of the positive current collector by adopting the same process, rolling by using the pressure of 6T, and further, cutting pieces and welding lugs to obtain the positive plate.
(3) Preparing an electrolyte: in a dry argon atmosphere, organic solvents of Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of 30:50:20, and then lithium salt of lithium hexafluorophosphate (LiPF) was added6) Dissolving and mixing evenly to obtain LiPF6Electrolyte with the concentration of 1.15 mol/L.
(4) Preparing a separator: rolling a 10 μm Polyimide (PI) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 2.5 μm to obtain a film A; rolling a 10 μm Polyimide (PI) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 5 μm to obtain a film B; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, where film B was attached to the negative electrode sheet.
(5) Preparing a lithium ion battery: and (3) relatively stacking and winding the positive plate, the negative plate and the partition plate, placing the positive plate, the negative plate and the partition plate into an outer packaging foil, and carrying out processes such as liquid injection, packaging and the like to obtain the lithium ion battery.
The positive electrode sheet, the negative electrode sheet, the electrolyte and the lithium ion battery of examples 4-2 to 4-8 were prepared in the same manner as in example 3-1, except that the rolling pressure of the positive electrode sheet, the rolling pressure of the negative electrode sheet and the preparation of the separator were different, as follows:
comparative examples 4 to 2
(1) The positive plate was rolled with a pressure of 6T, and the negative plate was rolled with a pressure of 6T.
(2) Preparing a separator: a10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was rolled with a roll gap of 2.5 μm to prepare a film A; film B was prepared by rolling a 10 μm polyvinylidene fluoride (PVDF) and Hexafluoropropylene (HFP) fiber film using a roll gap of 5 μm; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, where film B was attached to the negative electrode sheet.
Comparative examples 4 to 3
(1) The positive plate was rolled with a pressure of 6T, and the negative plate was rolled with a pressure of 6T.
(2) Preparing a separator: a10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was rolled with a roll gap of 2.5 μm to prepare a film A; one surface of the film A was coated with 5 μm alumina (Al)2O3) (PVDF content 10%), and attaching a negative plate to one surface of the membrane A coated with alumina.
Comparative examples 4 to 4
(1) The positive plate was rolled with a pressure of 6T, and the negative plate was rolled with a pressure of 6T.
(2) Preparing a separator: rolling a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film with a roll gap of 5 μm to obtain a film a; one surface of the film A was coated with 5 μm alumina (Al)2O3) (PVDF content 10%), and a negative electrode sheet was attached to one surface of the film A made of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP).
Comparative examples 4 to 5
(1) The positive plate was rolled with a pressure of 6T, and the negative plate was rolled with a pressure of 6T.
(2) Preparing a separator: rolling a 10 μm Polyimide (PI) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 2.5 μm to obtain a film A; one surface of the film A was coated with 5 μm alumina (Al)2O3) (15% of PVDF), and attaching a negative plate to one surface of the membrane A, which is made of Polyimide (PI) and polyvinylidene fluoride (PVDF).
Comparative examples 4 to 6
(1) The positive plate was rolled with a pressure of 6T, and the negative plate was rolled with a pressure of 6T.
(2) Preparing a separator: a10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was rolled with a roll gap of 2.5 μm to prepare a film A; rolling a 10 μm Polyimide (PI) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 5 μm to obtain a film B; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, where film B was attached to the negative electrode sheet.
Comparative examples 4 to 7
(1) The positive electrode sheet was rolled with a pressure of 6T, and the negative electrode sheet was rolled with a pressure of 7T.
(2) Preparing a separator: a10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was rolled with a roll gap of 2.5 μm to prepare a film A; rolling a 10 μm Polyimide (PI) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 5 μm to obtain a film B; film a and film B, to which the negative electrode sheet was attached, were stacked and roll-compounded using a 7.5 μm roll gap.
Comparative examples 4 to 8
(1) The positive electrode sheet was rolled with a pressure of 6T, and the negative electrode sheet was rolled with a pressure of 7T.
(2) Preparing a separator: a10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was rolled with a roll gap of 1.5 μm to prepare a film A; rolling a 10 μm Polyimide (PI) and polyvinylidene fluoride (PVDF) fiber film with a roll gap of 8 μm to obtain a film B; film a and film B, to which the negative electrode sheet was attached, were stacked and roll-compounded using a 9.5 μm roll gap.
The test data results are shown in table 4:
TABLE 4
According to the data result, the following data can be obtained:
(1) because the interfacial deformation rate of the negative electrode active material layer is greater than that of the positive electrode active material layer in the reaction process, the adhesive force (negative electrode side) of the second porous layer of the separator is controlled to be greater than that (positive electrode side) of the first porous layer, the ion transmission performance between the positive plate and the negative plate is not influenced while the negative electrode side interface is improved, and the working impedance of the lithium ion battery is favorably reduced.
The electrochemical device 100 of the embodiment of the present application has the following beneficial effects: the electrochemical device 100 comprises a positive plate 11, a negative plate 12 and a separator 13, the separator 13 is located between the positive plate 11 and the negative plate 12, the separator 13 comprises a first porous layer 131 and a second porous layer 133, the average pore diameter of the first porous layer 131 is smaller than the average pore diameter of the second porous layer 133, the positive plate 11 is attached to the surface of the first porous layer 131, the negative plate 12 is attached to the surface of the second porous layer 133, by providing a structure in which porous layers with different average pore diameters are respectively attached to the positive plate 11 and the negative plate 12 on the separator 13, the reasonable distribution of the electrolyte 30 at the interfaces between the positive plate 11 and the separator 13, and between the negative plate 12 and the separator 13 can be realized, the ion transport capacity of the interfaces between the positive plate 11 and the separator 13, and between the negative plate 12 and the separator 13 can be balanced, the operation of the electrochemical device 100 can be reduced, the internal resistance can be favorable for balancing the charge polarization of the electrochemical device 100, the discharge capacity of the electrochemical device 100 is improved.
Based on the same inventive concept, an electrical device is further provided in the embodiments of the present application, including an electrochemical device 100, where the electrochemical device 100 is used to provide electrical energy for the electrical device, and for specific structures and functions of the electrochemical device 100, please refer to the above embodiments, which are not described herein again. The electric equipment can be mobile phones, tablet computers, unmanned aerial vehicles and other electric equipment which need to be driven by electricity.
The above description is only an example of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings, or which are directly or indirectly applied to other related technical fields, are intended to be included within the scope of the present application.
Claims (10)
1. An electrochemical device comprising a positive plate, a negative plate, and a separator, the separator being located between the positive plate and the negative plate,
the separator comprises a first porous layer and a second porous layer, the positive electrode sheet is arranged on the surface of the first porous layer, the negative electrode sheet is arranged on the surface of the second porous layer, the average pore diameter of the first porous layer is A1 μm, the average pore diameter of the second porous layer is A2 μm, and the A1 and the A2 meet the following requirements: a1 < A2.
2. The electrochemical device according to claim 1,
the average pore diameter a1 of the first porous layer satisfies: a1 is more than or equal to 0.01 mu m and less than or equal to 0.05 mu m.
3. The electrochemical device according to claim 1,
the average pore diameter a2 of the second porous layer satisfies: a2 is more than 0.05 μm and less than or equal to 1 μm.
4. The electrochemical device according to claim 1,
the negative plate comprises a negative current collector and a negative active material layer positioned on the negative current collector; the surface of the negative active material layer is vertical to the direction of the negative current collector, and the cross-section porosity of 10 mu m of the surface of the negative active material layer is N10，2≤N10/A2≤5。
5. The electrochemical device according to claim 4,
the positive plate comprises a positive current collector and a positive active material layer positioned on the positive current collector; the surface of the positive electrode active material layer is vertical to the direction of the positive electrode current collector, and the cross-section porosity of 10 mu m of the surface of the positive electrode active material layer is P10，2≤P10/A1≤10。
6. The electrochemical device according to claim 5, wherein the following is satisfied:
0.3≤(N10/A2)/(P10/A1)≤0.75。
7. the electrochemical device according to claim 5, wherein the following is satisfied:
20％≤N10≤30％；10％≤P10≤20％。
8. the electrochemical device according to claim 1,
the adhesion force F1 between the first porous layer and the positive electrode sheet, and the adhesion force F2 between the second porous layer and the negative electrode sheet satisfy: f1 < F2.
9. The electrochemical device according to claim 1,
the contact angle of the first porous layer is theta 1, the contact angle of the second porous layer is theta 2, and the theta 1 and the theta 2 satisfy: theta 1 is more than or equal to theta 2, and theta 1 is less than or equal to 10 degrees.
10. An electrical consumer comprising an electrochemical device according to any one of claims 1 to 9 for providing electrical energy to the electrical consumer.
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| JP2008234853A (en) * | 2007-03-16 | 2008-10-02 | Matsushita Electric Ind Co Ltd | Separator for nonaqueous secondary battery, and nonaqueous secondary battery having the same |
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| US20190190078A1 (en) * | 2017-12-19 | 2019-06-20 | Sumitomo Chemical Company, Limited | Nonaqueous electrolyte secondary battery |
| CN113161515A (en) * | 2021-03-31 | 2021-07-23 | 宁德新能源科技有限公司 | Electrochemical device and electronic device |
| WO2021172195A1 (en) * | 2020-02-28 | 2021-09-02 | 帝人株式会社 | Separator for non-aqueous secondary battery, and non-aqueous secondary battery |
| CN113437250A (en) * | 2021-06-21 | 2021-09-24 | 宁德新能源科技有限公司 | Electrochemical device and electronic device |
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| JP2008234853A (en) * | 2007-03-16 | 2008-10-02 | Matsushita Electric Ind Co Ltd | Separator for nonaqueous secondary battery, and nonaqueous secondary battery having the same |
| US20160064715A1 (en) * | 2013-03-26 | 2016-03-03 | Nissan Motor Co., Ltd. | Non-aqueous electrolyte secondary battery |
| WO2016204397A1 (en) * | 2015-06-19 | 2016-12-22 | 삼성에스디아이 주식회사 | Highly heat-resistant separation membrane and electrochemical cell comprising same |
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