CN114614200B - Electrochemical device and electric equipment - Google Patents

Electrochemical device and electric equipment Download PDF

Info

Publication number
CN114614200B
CN114614200B CN202210346673.7A CN202210346673A CN114614200B CN 114614200 B CN114614200 B CN 114614200B CN 202210346673 A CN202210346673 A CN 202210346673A CN 114614200 B CN114614200 B CN 114614200B
Authority
CN
China
Prior art keywords
porous layer
film
negative electrode
electrochemical device
plate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202210346673.7A
Other languages
Chinese (zh)
Other versions
CN114614200A (en
Inventor
翁秋燕
盛阳平
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ningde Amperex Technology Ltd
Original Assignee
Ningde Amperex Technology Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ningde Amperex Technology Ltd filed Critical Ningde Amperex Technology Ltd
Priority to CN202210346673.7A priority Critical patent/CN114614200B/en
Publication of CN114614200A publication Critical patent/CN114614200A/en
Application granted granted Critical
Publication of CN114614200B publication Critical patent/CN114614200B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • 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
    • 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
    • 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
    • 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
    • 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
    • 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, the electrochemical device comprises a positive plate, a negative plate and a baffle, wherein the baffle is located between the positive plate and the negative plate, the baffle 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 arranged on the surface of the first porous layer, the negative plate is arranged on the surface of the second porous layer, the porous layers which are respectively attached to the positive plate and the negative plate are different in average pore diameter through the arrangement of the baffle, the reasonable distribution of the electrolyte at the interface between the positive plate and the baffle, the balance of the interface between the positive plate and the baffle and the ion transmission capacity between the negative plate and the baffle are realized, the work internal resistance of the electrochemical device is reduced, the charge polarization of the electrochemical device is facilitated to be balanced, and the discharge capacity of the electrochemical device is improved.

Description

Electrochemical device and electric equipment
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
Along with the rapid development of lithium ion batteries, the lithium ion batteries are widely applied to the fields of electronic communication, energy storage, power supply and the like. The separator for the lithium ion battery is one of the key inner layer components of the battery, is positioned between the positive electrode and the negative electrode, prevents short circuit caused by contact between the positive electrode and the negative electrode, allows electrolyte ions to pass through, determines the interface structure, the internal resistance and the like of the battery, and has the performance difference which directly influences the capacity, the circulation, the charge and discharge, the safety and the like of the lithium ion battery and the performance consistency, and the battery separator with excellent performance plays an important role in improving the comprehensive performance of the battery.
In practicing the embodiments of the present application, the inventors found that: at present, the traditional battery separator has contradiction between porosity, air permeability and heat shrinkage performance, namely, when the porosity is high and the air permeability is low, the heat shrinkage performance of the battery separator is poor, when the heat shrinkage performance of the battery separator is enhanced, the porosity is low, the air permeability is high, and the service characteristics and the safety performance of the battery are affected.
Disclosure of Invention
The technical problem that this application embodiment mainly solves is to provide an electrochemical device and consumer, can have macropore aperture and aperture simultaneously for the diaphragm can have high porosity, when thermal contraction performance is good.
In order to solve the technical problems, a technical scheme adopted by the embodiment of the application is as follows: the utility model provides an electrochemical device, including positive plate, negative plate and baffle, the baffle is located the positive plate with between the negative plate, the baffle includes first porous layer and second porous layer, the positive plate set up in first porous layer surface, the negative plate set up in second porous layer surface, the average pore size of first porous layer is A1 mu m, the average pore size of second porous layer is A2 mu m, A1 with A2 satisfies: 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 μm and less than or equal to 0.05 μm.
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 tab 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 faces to the direction perpendicular to the negative electrode current collector, and the 10 mu m section porosity of the surface of the negative electrode active material layer is N 10 ，2≤N 10 /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 faces to the direction perpendicular to the positive electrode current collector, and the section porosity of 10 mu m of the surface of the positive electrode active material layer is P 10 ，2≤P 10 /A1≤10。
In some embodiments, the electrochemical device satisfies: n is less than or equal to 0.3 10 /A2)/(P 10 /A1)≤0.75。
In some embodiments, the electrochemical cellThe learning device satisfies the following conditions: n is more than or equal to 20 percent 10 ≤30％；10％≤P 10 ≤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 is less than F2.
In some embodiments, the contact angle of the first porous layer is θ1 and the contact angle of the second porous layer is θ2, the θ1 and the θ2 satisfying: θ1 is equal to or greater than θ2, and θ1 is equal to or less than 10 degrees.
In order to solve the technical problems, another technical scheme adopted in the embodiment of the application is as follows: an electric device is provided, which comprises the electrochemical device, and the electrochemical device is used for providing electric energy for the electric device.
The electrochemical device 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 respectively attached to the positive plate and the negative plate through structures arranged on the partition plate, electrolyte can be reasonably distributed at the interface between the positive plate and the partition plate, the ion transmission capacity of the interface between the negative plate and the partition plate is balanced, the working internal resistance of the electrochemical device is reduced, the charge polarization of the electrochemical device is balanced, and the discharge capacity of the electrochemical device is improved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are used in the description of the embodiments or the prior art will be briefly described below. Like elements or portions are generally identified by like reference numerals throughout the several figures. In the drawings, elements or portions thereof are not necessarily drawn to scale.
Fig. 1 is a cross-sectional view of an electrochemical device according to an embodiment of the present application from one perspective.
Fig. 2 is an enlarged view of a portion M in an electrochemical device according to an embodiment of the present application.
Fig. 3 is an enlarged view of a portion M in an electrochemical device according to another embodiment of the present application.
Fig. 4 is a cross-sectional view of an electrochemical device according to yet another embodiment of the present application from one perspective.
Reference numerals in the specific embodiments are as follows:
100 electrochemical device 13 Partition board
10 Electrode assembly 131 A first porous layer
11 Positive plate 132 First Polymer
111 Positive electrode current collector 133 A second porous layer
112 Positive electrode active material layer 134 Second Polymer
12 Negative plate 135 Substrate layer
121 Negative electrode current collector 20 Packaging shell
122 Negative electrode active material layer 30 Electrolyte solution
Detailed Description
In order to facilitate an understanding of the present application, the present application will be described in more detail below with reference to the accompanying drawings and specific examples. It will be understood that when an element is referred to as being "fixed" to another element, it can be directly on the other element or one or more intervening elements may be present therebetween. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present therebetween. The terms "upper," "lower," "inner," "outer," "vertical," "horizontal," and the like as used in this specification, refer to an orientation or positional relationship based on that shown in the drawings, merely for convenience of description and to simplify the description, and do not denote or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus 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. The term "and/or" as used in this specification includes any and all combinations of one or more of the associated listed items.
In addition, the technical features described below in the different embodiments of the present application may be combined with each other as long as they do not collide 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 immersed in the electrolyte 30. Electrolyte 30 provides an ion transport environment for the electrochemical reaction of electrode assembly 10.
Noteworthy are: 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 may also be a hard shell battery, and the package case 20 is made of a hard material, for example: and (3) metal.
The electrode assembly 10 includes a positive electrode sheet 11, a negative electrode sheet 12, and a separator 13. The positive electrode sheet 11, the separator 13, and the negative electrode sheet 12 are stacked in this order and wound to form the electrode assembly 10. The positive electrode sheet 11 comprises a positive electrode current collector 111 and a positive electrode active material layer 112, wherein the positive electrode active material layer 112 is coated on two surfaces of the positive electrode current collector 111 which are oppositely arranged, and the cross-section porosity of 10 microns of the surface of the positive electrode active material layer 112 is P along the direction of the positive electrode active material layer 112 perpendicular to the positive electrode current collector 111 10 Wherein P is 10 The method meets the following conditions: p is 10% or less 10 Less than or equal to 20 percent. The negative electrode sheet 12 includes a negative electrode current collector 121 and a negative electrode active material layer 122, both surfaces of the negative electrode current collector 121 which are disposed opposite to each other are coated with the negative electrode active material layer 122, and the negative electrode active material layer 122 is oriented in a direction perpendicular to the negative electrode current collector 121On the surface of the negative electrode active material layer 122, the cross-sectional porosity of 10 μm was N 10 Wherein N is 10 The method meets the following conditions: n is more than or equal to 20 percent 10 ≤30％。
The positive electrode active material layer 112 and the negative electrode active material layer 122 are mainly used for participating in electrochemical reaction, and too small a porosity of the positive electrode active material layer 112 and a porosity of the negative electrode active material layer 122 can affect 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, reduce a transmission channel of lithium ions, prevent reaction between the positive electrode sheet 11 and the negative electrode sheet 12, and reduce reaction efficiency; too much porosity of the positive electrode active material layer 112 and the negative electrode active material layer 122 results in a decrease in the content of the positive electrode active material and the content of the negative electrode active material, thereby decreasing the capacity of the electrochemical device 100, and thus, the porosity P of the positive electrode active material layer 112 10 And the porosity N of the anode active material layer 122 10 The electrolyte 30 needs to be arranged in a reasonable range, which is beneficial to improving the wettability of the electrolyte 30 on the positive electrode plate 11 and the negative electrode plate 12, improving the probability of smooth deintercalation of lithium ions and improving the ion transmission performance of the electrode plates.
The separator 13 includes a first porous layer 131 and a second porous layer 133, the first porous layer 131 and the second porous layer 133 being stacked on each other, a surface of the first porous layer 131 being provided in contact with a surface of the positive electrode active material layer 112 of the positive electrode sheet 11, and a surface of the second porous layer 133 being provided in contact with a surface of the negative electrode active material layer 122 of the negative electrode sheet 12. The average pore diameter of the first porous layer 131 is A1 μm, and the average pore diameter of the second porous layer 133 is A2 μm, wherein A1 and A2 satisfy: a1 < A2, preferably, the average pore diameter A1 of the first porous layer 131 satisfies: the average pore diameter A2 of the second porous layer 133 satisfies 0.01 μm.ltoreq.A1.ltoreq.0.05 μm: a2 is more than 0.05 μm and less than or equal to 1 μm. The average pore diameter of the second porous layer 133 of the separator 13 is larger than that of the first porous layer 131, and the second porous layer 133 is attached to the negative electrode sheet 12, the first porous layer 131 is attached to the positive electrode sheet 11, so that the expansion condition of the negative electrode sheet 12 in the circulation process can be relieved, the second porous layer 133 with larger average pore diameter is beneficial to improving the liquid retention amount of the electrolyte 30 at the negative electrode side, the circulation tension of the negative electrode sheet 12 is reduced, and meanwhile, the first porous layer 131 with smaller average pore diameter is beneficial to the safety performance of the electrochemical device. The separator 13 simultaneously has the first porous layer 131 having a smaller average pore diameter and the second porous layer 133 having a larger average pore diameter, and can effectively improve the energy density of the electrochemical device 100.
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, where the first porous layer 131 and the second porous layer 133 are disposed on two sides of the substrate layer 135, respectively. It can be 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 impedance can be reduced, the cycle performance of the electrochemical device can be improved, and the discharge capacity can be improved.
Defining the section porosity P of the positive electrode active material layer 112 surface thickness of the positive electrode sheet 11 of 10 μm 10 The ratio to the average pore diameter A1 of the first porous layer 131 of the separator 13 is a first interface ratio that satisfies: p is more than or equal to 2 10 A1 is less than or equal to 10. Cross-sectional porosity N defining the negative electrode active material layer 122 surface thickness of the negative electrode sheet 12 to 10 μm 10 The ratio to the average pore diameter A2 of the second porous layer 133 of the separator 13 is a second interface ratio that satisfies: n is more than or equal to 2 10 A2 is less than or equal to 5. The first interface ratio characterizes the degree of interface matching between the surface of the positive electrode active material layer 112 and the surface of the first porous layer 131, and is too large or too small, so that ion transmission between the positive electrode sheet 11 and the separator 13 is easily affected; the second interface ratio characterizes the degree of interface matching between the surface of the anode active material layer 122 and the surface of the second porous layer 133, and is too large or too small, which easily results in the influence of ion transport between the anode sheet 12 and the separator 13, thereby influencing the chemical reaction between the cathode sheet 11 and the anode sheet 12, and therefore, both 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)/(P 10 In the electrochemical device 100, the positive electrode interface, the separator 13 and the negative electrode interface, and when the second interface ratio is smaller than the first interface ratio, i.e., the third interface ratio is fullFoot: 0.2 < (N) 10 /A2)/(P 10 A1) < 1, preferably 0.3.ltoreq.N 10 /A2)/(P 10 and/A1) is less than or equal to 0.75, at this time, the first porous layer 131 having a smaller average pore diameter cooperates 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 includes a first polymer 132, and the first polymer 132 includes 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 polymer, a styrene-acrylate copolymer, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, an acrylonitrile-acrylate copolymer, a vinyl chloride-acrylate copolymer, or a butadiene-styrene copolymer.
An adhesive force F1 between the first porous layer 131 and the positive electrode sheet 11, and an adhesive force F2 between the second porous layer 133 and the negative electrode sheet 12 satisfy: f1 is less than F2. In the cycle, the cycle tension of the negative electrode sheet 12 is large, and thus 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 adhesion between the negative electrode sheet 12 and the separator 13 is improved, and at the same time, the ion transmission performance between the positive electrode sheet 11 and the negative electrode sheet 12 is not affected, which is beneficial to reducing the impedance of the electrochemical device 100 and improving the charge and discharge performance of the electrochemical device 100.
The contact angle of the first porous layer 131 is θ1, the contact angle of the second porous layer 133 is θ2, and the θ1 and the θ2 satisfy: θ1 is equal to or greater than θ2, and θ1 is equal to or less than 10 degrees. The contact angle of the surface layer of the separator 13 reflects the affinity between the separator 13 and the electrolyte 30 in the electrochemical device 100. Specifically, in the present application, the second porous layer 133 on the negative electrode sheet 12 side is designed to have a larger average pore diameter, so in order to improve the interfacial properties of the separator 13, to increase the retention amount of the electrolyte 30 at the interface on the negative electrode sheet 12 side, it is necessary to reduce the contact angle θ2 of the second porous layer 131. Therefore, the contact angle θ2 of the second porous layer 133 is smaller than the contact angle θ1 of the first porous layer 131, and, preferably, the contact angle θ1 of the first porous layer 131 and the contact angle θ2 of the second porous layer 133 are smaller than or equal to 10 degrees. Because the main limiting point of the quick charge performance of the battery is at the negative plate 12 side, when the wettability of the electrolyte 30 at the negative plate 12 side is better than that at the positive plate 11 side, the impedance of the electrochemical device 100 is reduced, and the rate capability is improved; if the contact angle θ1 of the first porous layer 131 and the contact angle θ2 of the second porous layer 133 are too large, the partial areas of the positive electrode sheet 11 and the negative electrode sheet 12 are likely to be poorly impregnated, and lithium deposition may be caused, which may affect the safety of the electrochemical device 100.
In some embodiments, referring to fig. 4, the electrode assembly 10 may further be a lamination structure formed by sequentially stacking the positive electrode sheet 11, the separator 13, and the negative electrode sheet 12.
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 comparison test is further performed in this embodiment, where, in this embodiment and the comparison example are both lithium ion batteries made by housing the electrode assembly 10 in the package case 20 and packaging the electrolyte 30 after pouring, of course, the embodiment mode of the present application is not limited thereto, and the specific test procedure is as follows:
comparative example 1
(1) Preparing a negative plate: mixing 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 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, and further, cutting and welding tabs to obtain a negative electrode plate.
(2) Preparation of a positive plate: mixing positive active materials lithium cobaltate (LiCoO 2), conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5, adding N-methyl pyrrolidone (NMP) as a solvent, preparing into slurry with 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. Then another positive electrode active material layer is formed on the other surface of the positive electrode current collector using the same process. Further, the positive plate is obtained through cutting and welding the tab.
(3) Preparation of electrolyte: in a dry argon environment, firstly, mixing organic solvents of Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) according to a mass ratio of 30:50:20, and then adding lithium hexafluorophosphate (LiPF 6) to dissolve and uniformly mix to obtain an electrolyte with LiPF6 concentration of 1.15 mol/L.
(4) Preparation of a separator: directly using 10 μm Polyethylene (PE) base film.
(5) Preparation of a lithium ion battery: and relatively stacking and winding the obtained positive plate, the obtained negative plate and the obtained 10 mu m Polyethylene (PE) base film, placing the positive plate, the negative plate and the Polyethylene (PE) base film into an outer packaging foil, and carrying out the procedures of liquid injection, packaging and the like 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) Preparation of a separator: a10 μm fibrous membrane was directly used.
(2) Preparation of a lithium ion battery: and (3) relatively stacking and winding the obtained positive plate, the obtained negative plate and the obtained 10 mu m fiber film, placing the stacked positive plate, the obtained negative plate and the obtained 10 mu m fiber film into an outer packaging foil, and carrying out the procedures of 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) Preparation of a separator: a10 μm fibrous film was bonded to a 5 μm Polyethylene (PE) substrate, and hot-pressed with a roll gap of 10 μm.
(2) Preparation of a lithium ion battery: and (3) relatively stacking and winding the obtained positive plate, negative plate and separator, placing the positive plate, the negative plate and the separator in an outer packaging foil, and performing the procedures of 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 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 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, and further obtaining a negative electrode plate through cutting pieces and welding tabs.
(2) Preparation of a positive plate: lithium cobalt oxide (LiCoO) as a positive electrode active material 2 ) Mixing conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5, adding N-methyl pyrrolidone (NMP) as a solvent, preparing into slurry with solid content of 0.75, uniformly stirring, uniformly coating the slurry on an anode current collector aluminum foil, and drying at 90 ℃ to obtain an anode active material layer. And then forming another positive electrode active material layer on the other surface of the positive electrode current collector by adopting the same process, rolling by using the pressure of 6T, and further, cutting and welding the tab to obtain the positive electrode plate.
(3) Preparation of electrolyte: in a dry argon atmosphere, the organic solvents Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of 30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF) was added 6 ) Dissolving and mixing uniformly to obtain LiPF 6 Electrolyte with a concentration of 1.15 mol/L.
(4) Preparation of a separator: a 10 μm polyvinylidene fluoride (PVDF) fiber film was roll-pressed using a roll gap of 2.5 μm to obtain film a; a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was roll-pressed with a roll gap of 5 μm to obtain film B; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, with film B attached to the negative plate.
(5) Preparation of a lithium ion battery: and relatively stacking and winding the obtained positive plate, negative plate and separator, placing the positive plate, the negative plate and the separator in an outer packaging foil, and performing the procedures of liquid injection, encapsulation and the like to obtain the lithium ion battery.
Test method
(1) Method for testing 02C discharge capacity preservation rate of lithium ion battery
The lithium ion battery is charged to 4.45V with a constant current of 0.7C after being kept stationary at 25 ℃ for 5 minutes, then is charged to 0.05C with a constant voltage of 4.45V, is kept stationary for 5 minutes, and is discharged to 3.0V with a constant current of 0.5C for 5 minutes. The above charge and discharge process was repeated, and discharge was performed at 0.1C, and the 0.1C discharge capacity of the lithium ion battery was recorded.
(2) Method for testing Direct Current Resistance (DCR) of lithium ion battery
At 25 ℃, the lithium ion battery is charged to 4.45V at a constant current of 1.5C, then is charged to 0.05C at a constant voltage of 4.45V, and is kept stand for 30 minutes. The voltage value was recorded as U1 by discharging at 0.1C for 10 seconds, and as U2 by discharging at 1C for 360 seconds. The charge and discharge 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 direct current resistance R of the lithium ion battery at 25 ℃ was calculated by the formula: r= (U2-U1)/(1C-0.1C).
(3) Method for testing average pore diameter of separator
Selecting a test area of 1000 mu m multiplied by 100 mu m on the surface of a baffle, counting all pores in the area, distinguishing the brightness between the baffle and the pores in an Image, wherein the higher brightness is the baffle material, the darker is the pore, processing the Image by adopting Image J software, adjusting the diaphragm to be a black back, adjusting the pore to be white, counting the pore diameter of the pore, and calculating to obtain the average pore diameter.
(4) Method for testing section porosity of positive and negative electrode active material layer
Sample preparation flow: cutting an active material layer to be 0.5cm multiplied by 1cm, adhering the cut active material layer on a silicon wafer carrier with the size of 1cm multiplied by 1.5cm by using conductive adhesive, and then polishing one end of a pole piece by using argon ions (the parameter: 8KV accelerating voltage, each sample is 4 h), wherein the argon ions are ionized by using a high-voltage electric field to generate ionic states, and bombarding the surface of the pole piece at a high speed under the action of the accelerating voltage, so that the pole piece is degraded layer by layer to achieve the polishing effect.
After the sample preparation was completed, it was analyzed by a Scanning Electron Microscope (SEM). The scanning electron microscope used in the application is JSM-6360LV type of JEOL company to analyze the morphology structure of the sample.
Active material layer different thickness section porosity test: selecting a test area of 1000 mu m multiplied by 10 mu m, counting gaps among all particles in a section at the thickness of 0 mu m to 10 mu m on the surface of the pole piece, distinguishing brightness between particles and pores in an Image, wherein the particles with higher brightness are darker pores, processing a picture by adopting Image J software, adjusting the particles to be black, adjusting the pores to be white, and counting the area of the pores accounting for the whole Image to obtain the section porosity. The surface porosity was counted in the same manner.
(5) Contact angle test method
At room temperature, 1 μl of electrolyte (electrolyte refers to the electrolyte formulation provided herein) was dropped onto the separator surface, and then optical imaging was performed by CCD (charge coupled device), and then the resulting image was fitted to obtain the contact angle of the electrolyte on the separator surface.
The positive electrode sheet, the negative electrode sheet, the electrolyte, and the lithium ion battery in examples 1-2 to 1-9 below were all prepared as in example 1-1, except that the roll gaps of the first porous layer and the second porous layer of the separator were different, and specific parameters and test results were as follows:
TABLE 1
Note that: 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.
From the above data results, it can be derived 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 separator and the positive plate and the negative plate can be distributed reasonably, the interface of the positive plate and the separator and the ion transmission capacity of the interface of the negative plate and the separator can be 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, reduce the working internal resistance of the lithium battery, but 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 unchanged, the discharge capacity of the lithium battery can be increased by increasing the average pore diameter of the first porous layer, the working internal resistance of the lithium battery is reduced, and the safety performance of the lithium battery is reduced.
Example 2-1
(1) Preparing a negative plate: mixing 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 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, and further obtaining a negative electrode plate through cutting pieces and welding tabs.
(2) Preparation of a positive plate: lithium cobalt oxide (LiCoO) as a positive electrode active material 2 ) Mixing conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5, adding N-methyl pyrrolidone (NMP) as a solvent, preparing into slurry with solid content of 0.75, uniformly stirring, uniformly coating the slurry on an anode current collector aluminum foil, and drying at 90 ℃ to obtain an anode active material layer. Then another positive electrode active material layer is formed on the other surface of the positive electrode current collector by the same process, and is rolled by using a pressure of 6T, and then the positive electrode current collector is rolledAnd in one step, cutting and welding the tab to obtain the positive plate.
(3) Preparation of electrolyte: in a dry argon atmosphere, the organic solvents Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of 30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF) was added 6 ) Dissolving and mixing uniformly to obtain LiPF 6 Electrolyte with a concentration of 1.15 mol/L.
(4) Preparation of a separator: a 10 μm polyvinylidene fluoride (PVDF) fiber film was roll-pressed using a roll gap of 2.5 μm to obtain film a; a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was roll-pressed with a roll gap of 4.5 μm to obtain film B; film a and film B were stacked and roll compounded using a 7 μm roll gap, with film B attached to the negative plate.
(5) Preparation of a lithium ion battery: and relatively stacking and winding the obtained positive plate, negative plate and separator, placing the positive plate, the negative plate and the separator in an outer packaging foil, and performing the procedures of liquid injection, encapsulation and the like to obtain the lithium ion battery.
The positive electrode sheet, the negative electrode sheet, the electrolyte and the lithium ion battery in examples 2-2 to 2-12 and comparative example 2-1 below were all prepared in the same manner as in example 1-1, except that the rolling pressures of the positive electrode sheet and the negative electrode sheet and the preparation of the separator were different, specifically as follows:
TABLE 2
From the above data results, it can be derived that:
(1) The porosity P10 of the positive electrode active material layer, 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 are controlled to be in a proper range, the condition 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 is met, the capacity of the lithium ion battery is higher, the working impedance of the lithium ion battery is reduced, and the rate capability of the lithium ion battery is improved.
Example 3-1
(1) Preparing a negative plate: mixing 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 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, and further obtaining a negative electrode plate through cutting pieces and welding tabs.
(2) Preparation of a positive plate: mixing positive active materials lithium cobaltate (LiCoO 2), conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5, adding N-methyl pyrrolidone (NMP) as a solvent, preparing into slurry with 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 forming another positive electrode active material layer on the other surface of the positive electrode current collector by adopting the same process, rolling by using the pressure of 6T, and further, cutting and welding the tab to obtain the positive electrode plate.
(3) Preparation of electrolyte: in a dry argon environment, firstly, mixing organic solvents of Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) according to a mass ratio of 30:50:20, and then adding lithium hexafluorophosphate (LiPF 6) to dissolve and uniformly mix to obtain an electrolyte with LiPF6 concentration of 1.15 mol/L.
(4) Preparation of a separator: a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed using a roll gap of 2.5 μm to obtain a film a; a 10 μm Polyethylene (PE) fiber film was roll-pressed with a roll gap of 5 μm to obtain film B; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, with film B attached to the negative plate.
(5) Preparation of a lithium ion battery: and relatively stacking and winding the obtained positive plate, negative plate and separator, placing the positive plate, the negative plate and the separator in an outer packaging foil, and performing the procedures of liquid injection, encapsulation and the like to obtain the lithium ion battery.
Examples 3-2 to 3-10, the positive electrode sheets, the negative electrode sheets, the electrolytes, and the lithium ion batteries of comparative examples 3-1 and 3-2 were all 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, specifically as follows:
example 3-2
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 6T.
(2) Preparation of a separator: a 10 μm Polyethylene (PE) fiber film was roll-pressed using a roll gap of 2.5 μm to obtain a film a; a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed 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, with film B attached to the negative plate.
Examples 3 to 3
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 6T.
(2) Preparation of a separator: a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was roll-pressed with a roll gap of 2.5 μm to obtain film a; a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed 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, with film B attached to the negative plate.
Examples 3 to 4
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 6T.
(2) Preparation of a separator: a 10 μm Polyethylene (PE) fiber film was roll-pressed using a roll gap of 2.5 μm to obtain a film a; a 10 μm Polyethylene (PE) fiber film was roll-pressed with a roll gap of 5 μm to obtain film B; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, with film B attached to the negative plate.
Examples 3 to 5
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 4T.
(2) Preparation of a separator: a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed using a roll gap of 2.5 μm to obtain a film a; a 10 μm Polyethylene (PE) fiber film was roll-pressed with a roll gap of 4.5 μm to obtain film B; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, with film B attached to the negative plate.
Examples 3 to 6
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 8T.
(2) Preparation of a separator: a 10 μm Polyethylene (PE) fiber film was roll-pressed using a roll gap of 2.5 μm to obtain a film a; a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed 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, with film B attached to the negative plate.
Examples 3 to 7
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 8T.
(2) Preparation of a separator: a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was roll-pressed with a roll gap of 2.5 μm to obtain film a; a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed 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, with film B attached to the negative plate.
Examples 3 to 8
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 8T.
(2) Preparation of a separator: a 10 μm Polyethylene (PE) fiber film was roll-pressed using a roll gap of 2.5 μm to obtain a film a; a 10 μm Polyethylene (PE) fiber film was roll-pressed with a roll gap of 8 μm to obtain film B; film a and film B were stacked and roll compounded using a 10.5 μm roll gap, with film B attached to the negative plate.
Examples 3 to 9
(1) The positive electrode sheet was rolled using a pressure of 7.5T, and the negative electrode sheet was rolled using a pressure of 8T.
(2) Preparation of a separator: a 10 μm Polyethylene (PE) fiber film was roll-pressed with a roll gap of 1.5 μm to obtain film a; a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed 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, with film B attached to the negative plate.
Examples 3 to 10
(1) The positive electrode sheet was rolled using a pressure of 7.5T, and the negative electrode sheet was rolled using a pressure of 8T.
(2) Preparation of a separator: a 10 μm Polyethylene (PE) fiber film was roll-pressed with a roll gap of 1.5 μm to obtain film a; a 10 μm Polyethylene (PE) fiber film was roll-pressed with a roll gap of 8 μm to obtain film B; film a and film B were stacked and roll compounded using a 9.5 μm roll gap, with film B attached to the negative plate.
Comparative example 3-1
(1) The positive electrode sheet was rolled using a pressure of 8T, and the negative electrode sheet was rolled using a pressure of 4T.
(2) Preparation of a separator: a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed using a roll gap of 4.5 μm to obtain a film a; a 10 μm Polyethylene (PE) fiber film was roll-pressed with a roll gap of 4.5 μm to obtain film B; film a and film B were stacked and roll compounded using a 9 μm roll gap, wherein film B was attached to the negative plate.
Comparative example 3-2
(1) The positive electrode sheet was rolled using a pressure of 8T, and the negative electrode sheet was rolled using a pressure of 4T.
(2) Preparation of a separator: a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was roll-pressed with a roll gap of 4.5 μm to obtain film a; a 10 μm Polyethylene (PE) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed 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, wherein film B was attached to the negative plate.
TABLE 3 Table 3
From the above data results, it is possible to obtain:
(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 better than that of the electrolyte on the surface of the first porous layer, the working impedance of the lithium ion battery is reduced, and the rate capability of the lithium ion battery is improved.
Example 4-1
(1) Preparing a negative plate: mixing 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 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, and further obtaining a negative electrode plate through cutting pieces and welding tabs.
(2) Preparation of a positive plate: lithium cobalt oxide (LiCoO) as a positive electrode active material 2 ) Mixing conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5, adding N-methyl pyrrolidone (NMP) as a solvent, preparing into slurry with solid content of 0.75, uniformly stirring, uniformly coating the slurry on an anode current collector aluminum foil, and drying at 90 ℃ to obtain an anode active material layer. And then forming another positive electrode active material layer on the other surface of the positive electrode current collector by adopting the same process, rolling by using the pressure of 6T, and further, cutting and welding the tab to obtain the positive electrode plate.
(3) Preparation of electrolyte: in a dry argon atmosphere, the organic solvents Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of 30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF) was added 6 ) Dissolving and mixing uniformly to obtain LiPF 6 Electrolyte with concentration of 1.15mol/L。
(4) Preparation of a separator: a 10 μm Polyimide (PI) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed using a roll gap of 2.5 μm to obtain a film a; a 10 μm Polyimide (PI) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed 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, with film B attached to the negative plate.
(5) Preparation of a lithium ion battery: and relatively stacking and winding the obtained positive plate, negative plate and separator, placing the positive plate, the negative plate and the separator in an outer packaging foil, and performing the procedures of liquid injection, encapsulation 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 all 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, specifically as follows:
comparative example 4-2
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 6T.
(2) Preparation of a separator: a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was roll-pressed with a roll gap of 2.5 μm to obtain film a; a 10 μm polyvinylidene fluoride (PVDF) and Hexafluoropropylene (HFP) fiber film was roll-pressed with a roll gap of 5 μm to obtain film B; film a and film B were stacked and roll compounded using a 7.5 μm roll gap, with film B attached to the negative plate.
Comparative examples 4 to 3
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 6T.
(2) Preparation of a separator: a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was roll-pressed with a roll gap of 2.5 μm to obtain film a; one surface of film A was coated with 5 μm of alumina (Al 2 O 3 ) (PVDF content 10%) film a was coated with alumina and a negative plate was attached to one surface.
Comparative examples 4 to 4
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 6T.
(2) Preparation of a separator: a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was roll-pressed with a roll gap of 5 μm to obtain film A; one surface of film A was coated with 5 μm of alumina (Al 2 O 3 ) (PVDF content 10%), a surface of film a was polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) was attached to a negative electrode sheet.
Comparative examples 4 to 5
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 6T.
(2) Preparation of a separator: a 10 μm Polyimide (PI) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed using a roll gap of 2.5 μm to obtain a film a; one surface of film A was coated with 5 μm of alumina (Al 2 O 3 ) (PVDF content 15%), a surface of film a was Polyimide (PI) and polyvinylidene fluoride (PVDF) was attached to a negative plate.
Comparative examples 4 to 6
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 6T.
(2) Preparation of a separator: a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was roll-pressed with a roll gap of 2.5 μm to obtain film a; a 10 μm Polyimide (PI) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed 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, with film B attached to the negative plate.
Comparative examples 4 to 7
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 7T.
(2) Preparation of a separator: a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was roll-pressed with a roll gap of 2.5 μm to obtain film a; a 10 μm Polyimide (PI) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed 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, with film B attached to the negative plate.
Comparative examples 4 to 8
(1) The positive electrode sheet was rolled using a pressure of 6T, and the negative electrode sheet was rolled using a pressure of 7T.
(2) Preparation of a separator: a 10 μm polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) fiber film was roll-pressed with a roll gap of 1.5 μm to obtain film a; a 10 μm Polyimide (PI) and polyvinylidene fluoride (PVDF) fiber film was roll-pressed 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, with film B attached to the negative plate.
Test data results are shown in table 4:
TABLE 4 Table 4
From the above data results, it is possible to obtain:
(1) The interfacial deformation rate of the anode active material layer is larger than that of the cathode active material layer in the reaction process, and the bonding force (anode side) of the second porous layer of the separator is larger than that of the first porous layer (cathode side) by controlling, so that the interface of the anode side is improved, the ion transmission performance between the anode plate and the cathode plate is not influenced, and the working impedance of the lithium ion battery is 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, wherein the separator 13 is positioned 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 that 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, the separator 13 is provided with a structure that the porous layers with different average pore diameters are attached to the positive plate 11 and the negative plate 12 respectively, so that reasonable distribution of the electrolyte 30 at the interface between the positive plate 11 and the separator 13 and between the negative plate 12 and the separator 13 can be realized, the ion transmission capacity of the interface between the positive plate 11 and the separator 13 is balanced, the working internal resistance of the electrochemical device 100 is reduced, the charge polarization of the electrochemical device 100 is facilitated, and the discharge capacity of the electrochemical device 100 is improved.
Based on the same inventive concept, the embodiment of the present application further provides an electric device, including the electrochemical device 100, where the electrochemical device 100 is configured to provide electric energy for the electric device, and for the specific structure and function of the electrochemical device 100, please refer to the above embodiment, and details are not repeated herein. The electric equipment can be mobile phones, tablet computers, unmanned aerial vehicles and other electric equipment needing electric drive.
The foregoing description is only exemplary embodiments of the present application and is not intended to limit the scope of the present application, and all equivalent structures or equivalent processes using the descriptions and the drawings of the present application, or direct or indirect application in other related technical fields are included in the scope of the present application.

Claims (9)

1. An electrochemical device comprises a positive plate, a negative plate and a separator, wherein the separator is positioned between the positive plate and the negative plate,
the separator comprises a first porous layer and a 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 average pore diameter of the first porous layer is A1 mu m, the average pore diameter of the second porous layer is A2 mu m, and the A1 and the A2 satisfy the following conditions: a1 < A2;
The negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector; the surface of the negative electrode active material layer faces to the direction perpendicular to the negative electrode current collector, and the 10 mu m section porosity of the surface of the negative electrode active material layer is N 10 ，2≤N 10 /A2≤5。
2. The electrochemical device according to claim 1, wherein,
the average pore diameter A1 of the first porous layer satisfies: a1 is more than or equal to 0.01 μm and less than or equal to 0.05 μm.
3. The electrochemical device according to claim 1, wherein,
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, wherein,
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 faces to the direction perpendicular to the positive electrode current collector, and the section porosity of 10 mu m of the surface of the positive electrode active material layer is P 10 ，2≤P 10 /A1≤10。
5. The electrochemical device according to claim 4, wherein:
0.3≤(N 10 /A2)/(P 10 /A1)≤0.75。
6. the electrochemical device according to claim 4, wherein:
20％≤N 10 ≤30％；10％≤P 10 ≤20％。
7. the electrochemical device according to claim 1, wherein,
The adhesive force F1 between the first porous layer and the positive electrode sheet, and the adhesive force F2 between the second porous layer and the negative electrode sheet satisfy: f1 is less than F2.
8. The electrochemical device according to claim 1, wherein,
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 the following conditions: θ1 is equal to or greater than θ2, and θ1 is equal to or less than 10 degrees.
9. An electrical consumer comprising an electrochemical device according to any one of claims 1-8, the electrochemical device being configured to provide electrical energy to the electrical consumer.
CN202210346673.7A 2022-03-31 2022-03-31 Electrochemical device and electric equipment Active CN114614200B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210346673.7A CN114614200B (en) 2022-03-31 2022-03-31 Electrochemical device and electric equipment

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210346673.7A CN114614200B (en) 2022-03-31 2022-03-31 Electrochemical device and electric equipment

Publications (2)

Publication Number Publication Date
CN114614200A CN114614200A (en) 2022-06-10
CN114614200B true CN114614200B (en) 2023-12-19

Family

ID=81866682

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210346673.7A Active CN114614200B (en) 2022-03-31 2022-03-31 Electrochemical device and electric equipment

Country Status (1)

Country Link
CN (1) CN114614200B (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
WO2016204397A1 (en) * 2015-06-19 2016-12-22 삼성에스디아이 주식회사 Highly heat-resistant separation membrane and electrochemical cell comprising same
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

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2980911B1 (en) * 2013-03-26 2018-06-06 Nissan Motor Co., Ltd Non-aqueous electrolyte secondary battery
JP6507218B1 (en) * 2017-12-19 2019-04-24 住友化学株式会社 Nonaqueous electrolyte secondary battery

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
WO2016204397A1 (en) * 2015-06-19 2016-12-22 삼성에스디아이 주식회사 Highly heat-resistant separation membrane and electrochemical cell comprising same
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
CN113161515A (en) * 2021-03-31 2021-07-23 宁德新能源科技有限公司 Electrochemical device and electronic device
CN113437250A (en) * 2021-06-21 2021-09-24 宁德新能源科技有限公司 Electrochemical device and electronic device

Also Published As

Publication number Publication date
CN114614200A (en) 2022-06-10

Similar Documents

Publication Publication Date Title
KR102140129B1 (en) Anode with mesh type insulating layer, lithium secondary battery containing the same
CN113097431B (en) Electrochemical device and electronic device
CN101662015A (en) Porous protective film layer-provided electrode, non-aqueous electrolyte secondary battery and method for manufacturing porous protective film layer-provided electrode
KR20200029961A (en) Positive electrode active material for lithium secondary battery and lithium secondary battery comprising the same
WO2022267535A1 (en) Lithium metal negative electrode plate, electrochemical apparatus, and electronic device
US20220376224A1 (en) Electrochemical apparatus and electronic apparatus
WO2022141508A1 (en) Electrochemical device and electronic device
CN111725468A (en) Silicon dioxide inorganic nanoparticle reinforced polyolefin diaphragm and application thereof
EP4318777A1 (en) Separator, and electrochemical device and electronic device comprising same
US20240079592A1 (en) Electrochemical Apparatus and Electronic Apparatus
WO2023273652A1 (en) Diaphragm, lithium-ion battery, battery module, battery pack and power device
CN112670450A (en) Negative pole piece for solid-state battery and preparation method and application thereof
CN114497557A (en) Electrochemical device and electronic device
WO2023082924A1 (en) Electrode sheet, lithium ion battery, battery module, battery pack, and electrical device
WO2023245839A1 (en) Separator, preparation method therefor, and secondary battery and electrical device related thereto
CN114614200B (en) Electrochemical device and electric equipment
US20220223876A1 (en) Electrode plate, electrochemical device, and electronic device
US20220311044A1 (en) Method of making composite polymer electrolyte for all solid-state lithium-ion battery
US20220209241A1 (en) Electrode plate, electrochemical device, and electronic device
CN114649500A (en) Negative electrode plate, electrochemical device and electronic equipment
WO2022198614A1 (en) Negative electrode material, preparation method therefor, electrochemical device, and electronic device
CN112886050B (en) Secondary battery and device containing the same
JP2023515152A (en) SEPARATOR, MANUFACTURING METHOD THEREOF AND RELATED SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK AND DEVICE
CN115104219A (en) Isolating membrane, preparation method thereof, and related secondary battery, battery module, battery pack and device
CN110635139A (en) Copper current collector, method for manufacturing the same, negative electrode, and secondary battery

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant