CN116345070A - Secondary battery, preparation method thereof and electronic device - Google Patents

Secondary battery, preparation method thereof and electronic device Download PDF

Info

Publication number
CN116345070A
CN116345070A CN202310262590.4A CN202310262590A CN116345070A CN 116345070 A CN116345070 A CN 116345070A CN 202310262590 A CN202310262590 A CN 202310262590A CN 116345070 A CN116345070 A CN 116345070A
Authority
CN
China
Prior art keywords
negative electrode
hot melt
diaphragm
melt adhesive
adhesive layer
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.)
Pending
Application number
CN202310262590.4A
Other languages
Chinese (zh)
Inventor
高恒
夏恒涛
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 CN202310262590.4A priority Critical patent/CN116345070A/en
Publication of CN116345070A publication Critical patent/CN116345070A/en
Pending legal-status Critical Current

Links

Images

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
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • H01M50/461—Separators, membranes or diaphragms characterised by their combination with electrodes with adhesive layers between electrodes and separators
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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
    • H01M50/431—Inorganic material
    • H01M50/434—Ceramics
    • 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
    • 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
    • H01M50/463—Separators, membranes or diaphragms characterised by their shape
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The application discloses a secondary battery, a preparation method thereof and an electronic device, wherein the secondary battery comprises a shell and an electrode assembly arranged in the shell; the electrode assembly comprises a positive electrode plate, a first diaphragm, a negative electrode plate and a second diaphragm which are sequentially stacked; the first diaphragm comprises a first substrate layer, a first hot melt adhesive layer and a first ceramic layer, wherein the first hot melt adhesive layer and the first ceramic layer are respectively arranged on two sides of the first substrate layer, the second diaphragm comprises a second substrate layer, and a second hot melt adhesive layer and a second ceramic layer are respectively arranged on two sides of the second substrate layer, and the first hot melt adhesive layer and the second hot melt adhesive layer are both opposite to the negative electrode plate; the first separator includes a first extension beyond the negative electrode tab in a direction perpendicular to a thickness direction of the electrode assembly, and the second separator includes a second extension beyond the negative electrode tab; the first extension part and the second extension part on two sides of the negative electrode plate on the outermost layer of the electrode assembly are bonded through the first hot melt adhesive layer and the second hot melt adhesive layer, so that the safety performance of the secondary battery is improved.

Description

Secondary battery, preparation method thereof and electronic device
Technical Field
The embodiment of the application relates to the technical field of energy storage, in particular to a secondary battery, a preparation method thereof and an electronic device.
Background
Currently, electronic devices on the market are usually equipped with a secondary battery, which supplies power to the electronic device to get rid of the limitation of a power line, such as a mobile phone and a tablet computer. The secondary battery comprises a shell and an electrode assembly positioned in the shell, wherein the electrode assembly comprises a positive electrode plate, a negative electrode plate and a diaphragm, and the diaphragm is positioned between the positive electrode plate and the negative electrode plate. Generally, in the direction perpendicular to the thickness direction of the electrode assembly, the negative electrode plate exceeds the positive electrode plate, so as to avoid the phenomenon that lithium is separated because lithium ions can be inserted into the negative electrode plate less than lithium ions extracted from the positive electrode during the charging process of the secondary battery.
The inventors of the present application, in carrying out the present application, found that: the area of the negative electrode plate beyond the edge of the positive electrode plate is easily affected by external force to influence the safety performance of the secondary battery.
Content of the application
In order to solve the above technical problems, embodiments of the present application provide a secondary battery and an electronic device capable of improving safety performance.
The technical scheme adopted for solving the technical problems in the embodiment of the application is as follows:
a secondary battery includes a case and an electrode assembly received in the case; in the thickness direction of the electrode assembly, the electrode assembly comprises a positive electrode plate, a negative electrode plate, a first diaphragm and a second diaphragm which are arranged in a stacked manner, wherein the negative electrode plate is positioned between the first diaphragm and the second diaphragm; the first diaphragm comprises a first substrate layer, the first substrate layer comprises a first surface and a second surface which are opposite, the second diaphragm comprises a second substrate layer, the second substrate layer comprises a third surface and a fourth surface which are opposite, the first surface and the third surface are opposite to each other, the second surface and the fourth surface are opposite to each other, and the anode pole piece is opposite to each other; in a direction perpendicular to the thickness direction of the electrode assembly, the negative electrode tab extends beyond the positive electrode tab, the first separator includes a first main body portion facing the negative electrode tab and a first extension portion connected to the first main body portion and extending beyond the negative electrode tab, the second separator includes a second main body portion facing the negative electrode tab and a second extension portion connected to the second main body portion and extending beyond the negative electrode tab, the first extension portion and the second extension portion being located on the same side of the negative electrode tab; the first diaphragm comprises a first hot melt adhesive layer arranged on the first surface and a first ceramic layer arranged on the second surface, the first hot melt adhesive layer is at least positioned at the first extension part, and the first ceramic layer is positioned at the first main body part and the first extension part; the second diaphragm comprises a second hot melt adhesive layer arranged on the third surface and a second ceramic layer arranged on the fourth surface, the second hot melt adhesive layer is at least positioned at the second extension part, and the second ceramic layer is positioned at the second main body part and the second extension part; the first extension part and the second extension part positioned at two sides of the negative electrode plate of the outermost layer of the electrode assembly are bonded through the first hot melt adhesive layer and the second hot melt adhesive layer.
So, be favorable to forming the confined area in the bonding position between first extension and the second extension, reduced the negative pole piece and surpassed the one side of positive pole piece when receiving the exogenic action, the risk that the material that drops outside the confined area is favorable to reducing the risk of material that drops and positive pole piece short circuit, has improved electrode assembly's stability, is favorable to improving the security performance of secondary cell. Simultaneously, the first ceramic layer on the first extension portion and the second ceramic layer on the second extension portion are favorable for preventing the first extension portion and the second extension portion from deformation when receiving external force, the strength of the first diaphragm and the second diaphragm is enhanced, the risk that the part of the negative electrode pole piece exceeding the positive electrode pole piece receives the external force is reduced, and the stability of the electrode assembly is further improved.
Optionally, the first separator further includes a third extension portion connected to the first body portion and exceeding the negative electrode tab, the third extension portion being located at two opposite ends of the first body portion from the first extension portion, the second separator further includes a fourth extension portion connected to the second body portion and exceeding the negative electrode tab, the fourth extension portion being located at two opposite ends of the second body portion from the second extension portion, and the third extension portion and the fourth extension portion located at two sides of the negative electrode tab of the outermost layer of the electrode assembly are bonded through the first hot melt adhesive layer and the second hot melt adhesive layer.
Therefore, the risk that the other end of the negative electrode plate exceeds the part of the material of the positive electrode plate and falls off is reduced, the risk that the falling-off material is in short circuit with the positive electrode plate is reduced, the stability of the electrode assembly is improved, and the safety performance of the secondary battery is enhanced. And, the first ceramic layer on the third extension portion and the second ceramic layer on the fourth extension portion help to prevent the third extension portion and the fourth extension portion from deforming when receiving external force, so that the risk that the negative electrode plate exceeds the positive electrode plate and is subjected to external force is reduced, and the stability of the electrode assembly is improved.
The first extension portion is adhered to the second extension portion, the third extension portion is adhered to the fourth extension portion, the first diaphragm and the second diaphragm form a bagged structure in the thickness direction perpendicular to the electrode assembly, expansion of the negative electrode plate is restrained, stability of the negative electrode plate is indirectly improved, safety performance of the electrode assembly is improved, and service life of the secondary battery is prolonged.
Optionally, the first hot melt adhesive layer includes a first portion and a second portion, along a thickness direction of the electrode assembly, a projection of the first portion is located in a projection of the negative electrode plate, a projection of the second portion is located outside the projection of the negative electrode plate, a viscous flow temperature of the first portion is A, and a viscous flow temperature of the second portion is B, so that the temperature of 10 ℃ < A-B is less than or equal to 120 ℃. Therefore, when the hot-pressing end of the hot-pressing instrument is used for pressing and heating the electrode assembly, and the second part positioned on the first extension part and the second extension part are bonded by being melted by heating, the first part positioned on the first main body part is not melted, and the risk that the surface micropores are blocked due to the melting of the first part at the overlapping part of the first substrate layer and the negative electrode plate is reduced.
Optionally, the second hot melt adhesive layer includes a third portion and a fourth portion, along the thickness direction of the electrode assembly, the projection of the third portion is located in the projection of the negative electrode plate, the projection of the fourth portion is located outside the projection of the negative electrode plate, the viscous flow temperature of the third portion is C, and the viscous flow temperature of the fourth portion is D, so that the temperature of 10 ℃ < C-D is less than or equal to 120 ℃.
When the viscous flow temperature of the third part and the fourth part meets the relational expression, the hot-pressing end of the hot-pressing instrument is helpful to reduce the risk that the surface micropores are blocked due to the melting of the third part at the part where the second substrate layer and the negative electrode plate are overlapped when the fourth part on the second extension part is bonded with the first extension part by the melting of the second part under heating when the electrode assembly is pressed and heated.
Optionally, the first part comprises a hot melt polymer, a binder and inorganic particles, at least one of the following conditions being met:
(1) The mass percentage of the hot melt polymer is 50% -97%;
the higher the content of the hot-melt polymer, the better the fluidity of the hot-melt polymer when it is converted into a viscous state, and the easier the adhesion when it is bonded. When the mass percentage of the hot-melt polymer satisfies the above relation, the bonding reliability is improved. The hot melt polymer comprises ethylene-vinyl acetate copolymer and/or polyethylene oxide.
(2) The mass percentage of the binder is 2% -49%; the binder comprises polyvinylidene fluoride.
(3) The mass percentage of the inorganic matters is 1-10%, and the porosity of the inorganic particles of the inorganic matters is more than 50%. The inorganic material may be SiO 2 、Al 2 O 3 And/or ZrO 2 。
Optionally, the first substrate layer has a thickness T 1 The thickness of the first ceramic layer is T 2 The thickness of the first hot melt adhesive layer is T 3 The thickness of the second substrate layer is T 4 The thickness of the second ceramic layer is T 5 The thickness of the second hot melt adhesive layer is T 6 The thickness of the negative electrode plate is t, and at least one of the following conditions is satisfied:
(1)3μm≤T 1 ≤9μm；
the thicker the first substrate layer, the better the deformation resistance of the first separator, but the corresponding space will occupy in the interior of the housing, the less space will be provided for the positive electrode sheet or the negative electrode sheet, which is unfavorable for improving the energy density of the secondary battery. When the thickness of the first substrate layer meets the relation, the thickness of the first substrate layer is proper, so that the requirement of the first diaphragm on deformation resistance can be met, and the risk of reducing the excessive space occupied by the first substrate layer can be met.
(2)1μm≤T 2 ≤5μm；
The larger the thickness of the first ceramic layer is, the more the first separator occupies the inner space of the case, which is unfavorable for improving the energy density of the secondary battery, while the smaller the thickness of the first ceramic layer is, the more the deformation resistance of the first separator is difficult to improve, which is unfavorable for enhancing the strength of the first separator. When the thickness of the first ceramic layer meets the relation, the thickness of the first ceramic layer is proper, so that the overall strength of the first diaphragm can be improved, the risk of occupying excessive space can be reduced, and the energy density of the secondary battery can be improved. Further, T is 1 μm or less 2 ≤2μm。
(3)0.5μm＜T 3 ≤6μm；
The thicker the first hot melt adhesive layer is, the more firmly the first hot melt adhesive layer and the second hot melt adhesive layer are bonded, but the more the internal space of the secondary battery is occupied, which is unfavorable for improving the energy density of the secondary battery, and simultaneously, the transmission of lithium ions is blocked to a certain extent. When the thickness of the first hot melt adhesive layer meets the relation, the thickness of the first hot melt adhesive layer is proper, so that the energy density of the secondary battery can be improved, and the risk of blocking lithium ion transmission is reduced while the first hot melt adhesive layer and the second hot melt adhesive layer are firmly bonded. Further, T is 1.5 μm or less 3 ≤5μm。
(4)80μm≤t≤300μm；
When the thickness of the negative electrode plate meets the relation, the thickness of the negative electrode plate is proper, and the energy density of the secondary battery is improved. Further, t is more than or equal to 80 μm and less than or equal to 100 μm.
(5)3μm≤T 4 ≤9μm；
The thicker the second substrate layer, the better the deformation resistance of the second separator, but the corresponding space will occupy in the interior of the housing, the less space will be provided for the positive electrode sheet or the negative electrode sheet, which is unfavorable for improving the energy density of the secondary battery. When the thickness of the second substrate layer meets the relation, the thickness of the second substrate layer is proper, so that the requirement of the second diaphragm on deformation resistance can be met, and the risk of reducing the excessive space occupied by the second substrate layer can be also met.
(6)1μm≤T 5 ≤5μm；
The larger the thickness of the second ceramic layer is, the more the second separator occupies the inner space of the case, which is unfavorable for improving the energy density of the secondary battery, while the smaller the thickness of the second ceramic layer is, the more difficult it is to improve the deformation resistance of the second separator, which is unfavorable for enhancing the strength of the second separator. When the thickness of the second ceramic layer meets the relational expression, the thickness of the second ceramic layer is proper, so that the overall strength of the second diaphragm can be improved, the risk of occupying excessive space can be reduced, and the energy density of the secondary battery can be improved.
(7)0.5μm＜T 6 ≤6μm。
The thicker the second hot melt adhesive layer is, the more firmly the second hot melt adhesive layer is bonded with the first hot melt adhesive layer, but the more the internal space of the secondary battery is occupied, which is unfavorable for improving the energy density of the secondary battery and simultaneously causes a certain obstruction to the transmission of lithium ions. When the thickness of the second hot melt adhesive layer meets the relation, the thickness of the second hot melt adhesive layer is proper, so that the energy density of the secondary battery can be improved, and the risk of blocking lithium ion transmission is reduced while the second hot melt adhesive layer is firmly bonded with the first hot melt adhesive layer.
Optionally, the thickness of the negative electrode plate is t, and the length of the first extension part and/or the second extension part in the direction perpendicular to the thickness direction of the electrode assembly is L, as viewed along the thickness direction of the electrode assembly, so that L is greater than or equal to 0.5mm, and L is greater than or equal to 5t.
When the relation is satisfied, the length of the first extension part and/or the second extension part in the thickness direction perpendicular to the electrode assembly is proper, the risk that the bonding effect is affected due to the fact that the length of the first extension part and/or the second extension part in the thickness direction perpendicular to the electrode assembly is smaller is reduced, the bonding reliability of the first extension part and the second extension part through the first hot melt adhesive layer and the second hot melt adhesive layer is ensured, meanwhile, the isolation effect of the positive electrode pole piece and the negative electrode pole piece is improved, and the risk of short circuit of the positive electrode pole piece and the negative electrode pole piece is reduced.
Optionally, the negative electrode sheet includes a negative electrode current collector, a first active material layer and a second active material layer, and along a thickness direction of the electrode assembly, the negative electrode current collector includes a first face near the first separator and a second face near the second separator, the first face is provided with the first active material layer, the second face is provided with the second active material layer, wherein the first active material layer includes a first active portion beyond an edge of the positive electrode sheet, the second active material layer includes a second active portion beyond an edge of the positive electrode sheet, the first active portion is bonded with the first hot melt adhesive layer, and the second active portion is bonded with the second hot melt adhesive layer. Therefore, the risk that the third active part and the fourth part are separated from the negative current collector under the action of external force can be reduced, and the stability of the negative electrode plate can be further improved.
The technical problems of the embodiment of the application are solved by adopting the following technical scheme:
an electronic device comprises the secondary battery.
The technical problems of the embodiment of the application are solved by adopting the following technical scheme:
a preparation method of the secondary battery is applied to the secondary battery and comprises the following steps: preparing an electrode assembly, wherein the electrode assembly comprises a positive electrode plate, a negative electrode plate and a diaphragm which are arranged in a superposed manner, the diaphragm comprises a first diaphragm and a second diaphragm, and the negative electrode plate is positioned between the first diaphragm and the second diaphragm; hot-pressing the electrode assembly to bond the first hot-melt adhesive layer and the second hot-melt adhesive layer, so that the first diaphragm and the second diaphragm jointly wrap the cathode pole piece; providing a packaging bag, placing the electrode assembly in the packaging bag, and hot-pressing and edge-sealing the packaging bag; electrolyte is injected into the packaging bag, and then the packaging bag is formed and kept stand.
Optionally, the step of preparing the electrode assembly includes: preparing at least two diaphragms, wherein the at least two diaphragms comprise a first diaphragm and a second diaphragm; providing a positive electrode plate and a negative electrode plate; and superposing the positive electrode plate, the negative electrode plate, the first diaphragm and the second diaphragm to finally form an electrode assembly, wherein the negative electrode plate is positioned between the first diaphragm and the second diaphragm.
Optionally, the step of preparing at least two diaphragms comprises: providing a separation substrate, a hot melt raw material and a ceramic raw material; uniformly mixing the hot melt collagen materials to obtain first mixed slurry; uniformly mixing the ceramic raw materials to obtain second mixed slurry; and coating the first mixed slurry on the first coating surface of the isolating substrate, coating the second mixed slurry on the second coating surface of the isolating substrate layer, and drying to obtain the diaphragm.
Drawings
One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which the figures of the drawings are not to be taken in a limiting sense, unless otherwise indicated.
Fig. 1 is a schematic view of a secondary battery according to one embodiment of the present application;
fig. 2 is a schematic view of the electrode assembly of fig. 1 taken along a line MM;
fig. 3 is a schematic view of the electrode assembly of fig. 1 taken along a line MM;
FIG. 4 is a partial schematic view of one embodiment of a first membrane bonded to a second membrane;
FIG. 5 is a partial schematic view of another embodiment of a first membrane bonded to a second membrane;
FIG. 6 is a schematic view of FIG. 2 taken along section line NN;
fig. 7 is a schematic step diagram of a method of manufacturing a secondary battery according to another embodiment of the present application;
fig. 8 is a step diagram of further refinement of step S201 in fig. 7;
fig. 9 is a step diagram of further refinement of step S2011 in fig. 8;
in the figure: 1. a secondary battery; 2. a housing; 3. an electrode assembly; 31. a negative electrode plate; 32. a positive electrode sheet; 33. a first diaphragm; 34. a second diaphragm; 311. a negative electrode current collector; 312. a first active material layer; 313. a second active material layer; 3111. a first face; 3112. a second face; 321. a positive electrode current collector; 322. a third active material layer; 323. a fourth active material layer; 330. a first body portion; 331. a first extension; 340. a second body portion; 341. a second extension; 31a, a first pole piece; 31b, a second pole piece; 332. a third extension; 342. a fourth extension; 333. a fifth extension; 343. a sixth extension; 334. a seventh extension; 344. an eighth extension; 3121. a first active moiety; 3131. a second active moiety; 3122. a third active moiety; 3132. a fourth active moiety; 3301. a first substrate layer; 33011. a first surface; 33012. a second surface; 3302. a first hot melt adhesive layer; 3303. a first ceramic layer; 3401. a second substrate layer; 34011. a third surface; 34012. a fourth surface; 3402. a second hot melt adhesive layer; 3403. a second ceramic layer; 33021. a first portion; 33022. a second portion; 34021. a third section; 34022. a fourth section; 4. a positive electrode tab; 5. and a negative electrode tab.
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.
As shown in fig. 1, one of the embodiments of the present application provides a secondary battery 1 including a case 2 and an electrode assembly 3, the electrode assembly 3 being accommodated in the case 2. The case 2 may be a packing bag, or may be other as long as the loading of the electrode assembly 3 is accomplished.
Referring to fig. 2, the electrode assembly 3 includes a negative electrode tab 31, a positive electrode tab 32, a first separator 33 and a second separator 34 that are stacked, the negative electrode tab 31 is located between the first separator 33 and the second separator 34, and the first separator 33 and the second separator 34 isolate the negative electrode tab 31 and the positive electrode tab 32 to reduce the risk of shorting the positive electrode tab 32 and the negative electrode tab 31. The negative electrode tab 31 extends beyond the positive electrode tab 32 in a direction perpendicular to the electrode assembly 3 when viewed along the thickness direction Z of the electrode assembly 3, which is beneficial to the fact that the lithium intercalation and deintercalation capability of the negative electrode tab 31 is greater than the lithium deintercalation capability of the positive electrode tab 32 when the secondary battery 1 is charged, and reduces the risk of lithium precipitation of the electrode assembly 3.
Negative electrode tab 31 includes a negative electrode current collector 311, a first active material layer 312, and a second active material layer 313, negative electrode current collector 311 includes a first face 3111 adjacent to first separator 33 and a second face 3112 adjacent to second separator 34, first active material layer 312 is disposed on first face 3111 of negative electrode current collector 311, and second active material layer 313 is disposed on second face 3112 of negative electrode current collector 311. The positive electrode sheet 32 includes a positive electrode current collector 321, a third active material layer 322, and a fourth active material layer 323, wherein the third active material layer 322 is disposed on one surface of the positive electrode current collector 321, and the fourth active material layer 323 is disposed on the other surface of the positive electrode current collector 321.
The electrode assembly 3 may be a wound structure or a laminated structure, and is specifically set as required. As shown in fig. 2, the electrode assembly 3 adopts a laminated structure, the number of the negative electrode pole piece 31, the positive electrode pole piece 32, the first diaphragm 33 and the second diaphragm 34 is plural, the plurality of the negative electrode pole pieces 31, the plurality of the positive electrode pole pieces 32, the plurality of the first diaphragms 33 and the plurality of the second diaphragms 34 are stacked, and the opposite surfaces of each negative electrode pole piece 31 are respectively provided with a first diaphragm 33 and a second diaphragm 34. As shown in fig. 3, the electrode assembly 3 adopts a wound structure in which a negative electrode tab 31, a positive electrode tab 32, a first separator 33, and a second separator 34 are stacked and wound, the negative electrode tab 31 being located between the first separator 33 and the second separator 34. For convenience of explanation, the technical solution of the present application will be described below using the lamination type structure of the electrode assembly 3 as an example, but the structure of the electrode assembly 3 of the present application is not limited to the lamination type structure.
The inventor of the present application found that, when the part of the negative electrode sheet 31 beyond the edge of the positive electrode sheet 32 is subjected to an external force, the part of the active material layer on the negative electrode sheet 31 is easy to fall off, and the falling material is in contact with the positive electrode sheet 32, so that the risk of short circuit is caused, based on the fact, the inventor of the present application improves the structure between the negative electrode sheet 31 and the diaphragm, and the scheme after improvement is specifically as follows:
As shown in fig. 2 and 4, in a direction perpendicular to the thickness direction Z of the electrode assembly 3, with reference to the negative electrode tab 31, the first separator 33 includes a first main body 330 facing the negative electrode tab 31 and a first extension 331 connected to the first main body 330 and extending beyond the negative electrode tab 31, the second separator 34 includes a second main body 340 and a second extension 341 connected to the second main body 340 and extending beyond the negative electrode tab 31, and the first extension 331 and the second extension 341 are located on the same side of the negative electrode tab 31.
The first separator 33 includes a first substrate layer 3301, a first hot melt adhesive layer 3302, and a first ceramic layer 3303, where the first substrate layer 3301 includes a first surface 33011 and a second surface 33012 that are disposed opposite to each other, the first surface 33011 is provided with the first hot melt adhesive layer 3302, the first hot melt adhesive layer 3302 is at least located at the first extending portion 331, the second surface 33012 is provided with the second ceramic layer 3403, and the second ceramic layer 3403 is at least located at the first main body portion 330 and the first extending portion 331.
The second separator 34 includes a second substrate layer 3401, a second hot melt adhesive layer 3402, and a second ceramic layer 3403, the second substrate layer 3401 includes a third surface 34011 and a fourth surface 34012, the third surface 34011 is provided with the second hot melt adhesive layer 3402, the second hot melt adhesive layer 3402 is at least partially located at the second extension 341, the fourth surface 34012 is provided with the second ceramic layer 3403, and the second ceramic layer 3403 is at least located at the second main body 340 and the second extension 341. Wherein, first surface 33011 and third surface 34011 are both facing negative electrode tab 31, and second surface 33012 and fourth surface 34012 are both facing positive electrode tab 32. In other words, the side of the first substrate layer 3301 facing the negative electrode tab 31 is the first surface 33011, and the side of the second substrate layer 3401 facing the negative electrode tab 31 is the third surface 34011.
In some embodiments, the first extension portion 331 and the second extension portion 341 located on two sides of the negative electrode tab 31 of the outermost layer of the electrode assembly 3 are bonded through the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402, that is, the first extension portion 331 and the second extension portion 341 are bonded, which is favorable to forming a closed area at the bonding position between the first extension portion 331 and the second extension portion 341, reducing the risk that the dropped material falls out of the closed area when the negative electrode tab 31 exceeds one side of the positive electrode tab 32 under the action of external force, being favorable to reducing the risk that the dropped material is shorted with the positive electrode tab 32, improving the stability of the electrode assembly 3, and being favorable to improving the safety performance of the secondary battery 1. Meanwhile, the first ceramic layer 3303 on the first extension 331 and the second ceramic layer 3403 on the second extension 341 help to prevent the first extension 331 and the second extension 341 from shrinking and deforming when heated, so that the strength and thermal stability of the first separator 33 and the second separator 34 are enhanced, and the stability of the electrode assembly 3 is further improved.
As shown in fig. 2 and 4, it is defined that, along the thickness direction Z of the electrode assembly 3, the negative electrode tab 31 located at the outermost layer of the electrode assembly 3 is a first electrode tab 31a, and the negative electrode tab 31 located in the middle of the negative electrode tab 31 located at the outermost layer of the electrode assembly 3 is a second electrode tab 31b. Further, the first extending portions 331 and the second extending portions 341 located at two sides of each second electrode tab 31b are bonded through the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402, which helps to reduce the risk that the material of the portion of the second electrode tab 31b beyond the positive electrode tab 32 falls off and is in short circuit with the adjacent positive electrode tab 32, which helps to improve the stability of the electrode assembly 3 and the safety performance of the secondary battery 1. Similarly, the first ceramic layer 3303 on the first extension 331 and the second ceramic layer 3403 on the second extension 341 on both sides of each second electrode tab 31b help to prevent the first extension 331 and the second extension 341 from shrinking and deforming when heated, thus enhancing the strength and thermal stability of the first separator 33 and the second separator 34 and further enhancing the stability of the electrode assembly 3.
It can be understood that during the process of manufacturing the electrode assembly 3, it is necessary to perform hot pressing on both sides of the thickness direction of the electrode assembly 3 in a rolled or laminated structure, so that the first hot melt adhesive layer 3302 on the first extending portions 331 and the second hot melt adhesive layer 3402 on the second extending portions 341 on both sides of the negative electrode tab 31 on the outermost layer are melted and bonded with each other, and the hot pressing end of the hot pressing device is far from the first extending portions 331 and the second extending portions 341 on both sides of the thickness of each second electrode tab 31b, so that the first extending portions 331 and the second extending portions 341 on both sides of each second electrode tab 31b are not bonded yet, and after the hot pressing parameters (such as prolonging the hot pressing time and increasing the hot pressing temperature) are properly adjusted, the first extending portions 331 and the second extending portions 341 on both sides of each second electrode tab 31b can be bonded with each other, which is helpful for further improving the safety performance of the second electrode assembly 31b and enhancing the stability of the electrode assembly 3.
In some embodiments, the first substrate layer 3301 has a thickness T 1 The thickness of the first ceramic layer 3303 is T 2 The first hot melt adhesive layer 3302 has a thickness T 3 The negative electrode tab 31 has a thickness t satisfying the following conditionsAt least one of:
(1)3μm≤T 1 ≤9μm；
the thicker the first base material layer 3301, the better the deformation resistance of the first separator 33, but the corresponding space will occupy in the interior of the case 2, the less space will be provided for the positive electrode tab 32 or the negative electrode tab 31, which is disadvantageous for improving the energy density of the secondary battery 1. When the thickness of the first substrate layer 3301 satisfies this relation, the thickness of the first substrate layer 3301 is more suitable, which can satisfy the requirement of the first separator 33 for deformation resistance, and also can satisfy the risk of reducing the excessive space occupied by the first substrate layer 3301.
(2)1μm≤T 2 ≤5μm；
The larger the thickness of the first ceramic layer 3303, the more the first separator 33 occupies the inner space of the case 2, which is disadvantageous in improving the energy density of the secondary battery 1, while the smaller the thickness of the first ceramic layer 3303, the more difficult it is to improve the deformation resistance heat resistance of the first separator 33, which is disadvantageous in enhancing the strength and thermal stability of the first separator 33. When the thickness of the first ceramic layer 3303 satisfies the above relation, the thickness of the first ceramic layer 3303 is relatively suitable, which can not only ensure the improvement of the overall strength and thermal stability of the first separator 33, but also reduce the risk of occupying excessive space, thereby being beneficial to the improvement of the energy density of the secondary battery 1.
(3)0.5μm＜T 3 ≤6μm；
The thicker the first hot melt adhesive layer 3302, the more firmly the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402 are bonded, but the more the internal space of the secondary battery 1 is occupied, which is unfavorable for improving the energy density of the secondary battery 1, and meanwhile, the transmission of lithium ions is blocked to some extent. When the thickness of the first hot melt adhesive layer 3302 satisfies the above relation, the thickness of the first hot melt adhesive layer 3302 is relatively suitable, which is helpful for improving the energy density of the secondary battery 1, and the risk of blocking lithium ion transmission is reduced while the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402 are firmly bonded.
(4)80μm≤t≤300μm。
The thicker the negative electrode 31 is, the farther the distance between the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402 is, which is unfavorable for the adhesion between the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402, the thinner the negative electrode 31 is, the processing difficulty rises, and when the thickness of the negative electrode 31 satisfies the relation, the thickness of the negative electrode 31 is more proper, which is favorable for the adhesion between the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402, and simultaneously improves the energy density of the secondary battery 1.
In some embodiments, further satisfaction is: (1) T is less than or equal to 1.5 mu m 3 ≤5μm；(2)1μm≤T 2 ≤2μm，(3)80μm≤t≤100μm。
Further, the second substrate layer 3401 has a thickness T 4 The second ceramic layer 3403 has a thickness T 5 The second hot melt adhesive layer 3402 has a thickness T 6 At least one of the following conditions is satisfied:
(5)3μm≤T 4 ≤9μm；
the thicker the second base material layer 3401, the better the deformation resistance of the second separator 34, but the corresponding space will occupy in the interior of the case 2, the less space will be provided for the positive electrode tab 32 or the negative electrode tab 31, which is disadvantageous in increasing the energy density of the secondary battery 1. When the thickness of the second substrate layer 3401 satisfies the relationship, the thickness of the second substrate layer 3401 is suitable, which can satisfy the requirement of the second separator 34 on the deformation resistance and reduce the risk of the second substrate layer 3401 occupying too much space.
(6)1μm≤T 5 ≤5μm；
The greater the thickness of the second ceramic layer 3403, the more the second separator 34 occupies the inner space of the case 2, which is disadvantageous in improving the energy density of the secondary battery 1, while the smaller the thickness of the second ceramic layer 3403, the more difficult it is to improve the deformation resistance and heat resistance of the second separator 34, which is disadvantageous in enhancing the strength and thermal stability of the second separator 34. When the thickness of the second ceramic layer 3403 satisfies the above relation, the thickness of the second ceramic layer 3403 is more suitable, so that the overall strength and thermal stability of the second separator 34 can be improved, and the risk of occupying excessive space can be reduced, thereby being beneficial to improving the energy density of the secondary battery 1.
(7)0.5μm＜T 6 ≤6μm。
The thicker the second hot melt adhesive layer 3402, the more firmly the second hot melt adhesive layer 3402 is adhered to the first hot melt adhesive layer 3302, but the more the inner space of the secondary battery 1 is occupied, which is unfavorable for improving the energy density of the secondary battery 1, and meanwhile, the transmission of lithium ions is blocked to some extent. When the thickness of the second hot-melt adhesive layer 3402 satisfies the above relation, the thickness of the second hot-melt adhesive layer 3402 is more suitable, which is helpful to improve the energy density of the secondary battery 1, and the risk of blocking lithium ion transmission is reduced while the second hot-melt adhesive layer 3402 is firmly bonded with the first hot-melt adhesive layer 3302.
In some embodiments, negative electrode tab 31 has a thickness t, and first extension 331 and/or second extension 341 has a length L in a direction perpendicular to thickness direction Z of electrode assembly 3, as viewed along thickness direction Z of electrode assembly 3, satisfying L.gtoreq.0.5 mm, and L.gtoreq.5 t. When the relation is satisfied, the length of the first extension portion 331 and/or the second extension portion in the thickness direction Z perpendicular to the electrode assembly 3 is appropriate, so that the risk that the bonding effect is affected due to the smaller length of the first extension portion 331 and/or the second extension portion 341 in the thickness direction perpendicular to the electrode assembly 3 is reduced, the bonding reliability of the first extension portion 331 and the second extension portion 341 through the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402 is ensured, the isolation effect of the positive electrode pole piece 32 and the negative electrode pole piece 31 is improved, and the risk that the positive electrode pole piece 32 and the negative electrode pole piece 31 are shorted is reduced.
In some embodiments, referring to fig. 2 and 4 again, the first separator 33 further includes a third extension portion 332 connected to the first main portion 330 and beyond the negative electrode tab 31, the third extension portion 332 and the first extension portion 331 are located at opposite ends of the first main portion 330, and the third extension portion 332 is provided with a first hot melt adhesive layer 3302; the second separator 34 further includes a fourth extension 342 connected to the second body portion 340 and exceeding the negative electrode tab 31, the fourth extension 342 being located at opposite ends of the second body portion 340 from the second extension 341, the fourth extension 342 being provided with a second hot melt adhesive layer 3402, and the third extension 332 and the fourth extension 342 located at both sides of the negative electrode tab 31 of the outermost layer of the electrode assembly 3 being bonded through the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402. Thus, the risk that the other end of the negative electrode pole piece 31 falls off from the part of the material exceeding the positive electrode pole piece 32 is reduced, the risk that the falling-off material is short-circuited with the positive electrode pole piece 32 is reduced, the stability of the electrode assembly 3 is improved, and the safety performance of the secondary battery 1 is enhanced. In addition, the first ceramic layer 3303 on the third extension portion 332 and the second ceramic layer 3403 on the fourth extension portion 342 help to block the deformation of the third extension portion 332 and the fourth extension portion 342 when the external force is applied, so that the risk that the negative electrode tab 31 exceeds the positive electrode tab 32 and is applied by the external force is reduced, and the stability of the electrode assembly 3 is improved.
The first extension portion 331 is bonded to the second extension portion 341 and the third extension portion 332 is bonded to the fourth extension portion 342, and the first separator 33 and the second separator 34 form a pouch structure in a direction Z perpendicular to the thickness direction of the electrode assembly 3, which helps to suppress expansion of the negative electrode tab 31, indirectly improve stability of the negative electrode tab 31, enhance safety performance of the electrode assembly 3, and improve lifetime of the secondary battery 1.
Further, the third extension 332 and the fourth extension 342 located at both sides of each second electrode tab 31b are bonded through the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402, which helps to reduce the risk of thermal imbalance caused by the material falling off of the portion of each second electrode tab 31b beyond the positive electrode tab 32 and shorting with the adjacent positive electrode tab 32, and further improves the stability of the electrode assembly 3. Similarly, when the third extending portions 332 and the fourth extending portions 342 are bonded to each other on both sides of the outermost negative electrode tab 31, whether the third extending portions 332 and the fourth extending portions 342 are bonded to each other on both sides of each second electrode tab 31b depends on the hot pressing parameters of the hot pressing apparatus when processing the electrode assembly 3, and will not be described herein.
In some embodiments, the directions defined from the first extension 331 to the third extension 332, the directions of the second extension 341 to the fourth extension 342 are all the first direction X, and the direction perpendicular to the first direction X and the thickness direction Z of the electrode assembly 3 is the second direction Y. When the electrode assembly 3 adopts the laminated structure, as shown in fig. 6, fig. 6 is a schematic view taken along a section line NN of fig. 5, the first separator 33 further includes a fifth extension 333 connected to the first body 330 and extending beyond the negative electrode tab 31 in the second direction Y, the fifth extension 333 is provided with a first hot melt adhesive layer 3302, the second separator 34 further includes a sixth extension 343 connected to the first body 330 and extending beyond the negative electrode tab 31, and the sixth extension 343 is provided with a second hot melt adhesive layer 3402. The fifth extension parts 333 and the sixth extension parts 343 which are positioned on two sides of the cathode pole piece 31 on the outermost layer of the electrode assembly 3 are mutually adhered through the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402, so that the risk that part of the material of the cathode pole piece 31 on the outermost layer exceeding the cathode pole piece 32 falls off is reduced, and the stability of the electrode assembly 3 is improved. Further, the fifth extension 333 and the sixth extension on both sides of each second pole piece 31b are adhered by the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402, which is beneficial to reducing the risk of falling off the material of the portion of the second pole piece 31b beyond the positive pole piece 32, and improving the safety performance of the second pole piece 31 b. Meanwhile, the first ceramic layer 3303 on the fifth extension part 333 and the second ceramic layer 3403 on the sixth extension part 343 on both sides of each second electrode tab 31b are beneficial to preventing the fifth extension part 333 and the sixth extension part 343 from deformation when external force is applied, so that the strength of the first diaphragm 33 and the second diaphragm 34 is enhanced, the risk that the negative electrode tab 31 exceeds the positive electrode tab 32 and is subjected to the action of the external force is reduced, and the stability of the electrode assembly 3 is further improved.
Further, the first separator 33 further includes a seventh extension portion 334 connected to the first main body portion 330 and extending beyond the negative electrode tab 31, the seventh extension portion 334 and the fifth extension portion 333 are disposed opposite to each other in the second direction Y, and the seventh extension portion 334 is provided with a first hot melt adhesive layer 3302. The second separator 34 further includes an eighth extension portion 344 connected to the second main body portion 340 and extending beyond the negative electrode tab 31, the eighth extension portion 344 and the sixth extension portion 343 being disposed opposite to each other in the second direction Y, the eighth extension portion 344 being provided with a second hot melt adhesive layer 3402. In some embodiments, seventh extensions 334 on both sides of outermost negative electrode tab 31 are bonded to eighth extensions 344, helping to reduce the risk of material shedding from the portion of negative electrode tab 31 beyond positive electrode tab 32, improving the stability of electrode assembly 3. In other embodiments, the seventh extension 334 and the eighth extension 344 of both sides of the second electrode tab 31b are bonded to each other, reducing the risk of material falling off of the portion of the negative electrode tab 31 beyond the positive electrode tab 32, and improving the stability of the electrode assembly 3. Meanwhile, the fifth extension part 343 and the sixth extension part 343 are mutually bonded, and the seventh extension part 334 and the eighth extension part 344 are mutually bonded to form a bagged structure, which is favorable for the first diaphragm 33 and the second diaphragm 34 to wrap the negative electrode plate 31 inside, is favorable for reducing the risk that the material of the part of the negative electrode plate 31 exceeding the positive electrode plate 32 falls off and is in short circuit with the positive electrode plate 32, improves the stability of the electrode assembly 3, can play a role in inhibiting the expansion of the negative electrode plate 31, and enhances the safety performance of the electrode assembly 3.
It should be understood that referring to fig. 4 and 5, the first surface 33011 may be provided with the first hot melt adhesive layer 3302 on the whole surface; the first hot melt adhesive layer 3302 may be provided only in a partial region, for example, the first surface 33011 may be provided with the first hot melt adhesive layer 3302 in the region of the first extension 331 and/or the third extension 332, and may be specifically set as needed.
In some embodiments, as shown in fig. 4, the first surface 33011 is provided with a first hot melt adhesive layer 3302 on the whole surface, the first hot melt adhesive layer 3302 includes a first portion 33021 and a second portion 33022, along the thickness direction Z of the electrode assembly 3, the projection of the first portion 33021 is located in the projection of the negative electrode tab 31, the projection of the second portion 33022 is located outside the projection of the negative electrode tab 31, the adhesive flow temperature of the first portion 33021 is a, and the adhesive flow temperature of the second portion 33022 is B, so that 10 ℃ < a-B is less than or equal to 120 ℃. That is, in the thickness direction Z of the electrode assembly 3, the region of the first separator 33 for overlapping with the negative electrode tab 31 is provided with the first portion 33021, and the region of the first separator 33 not in contact with the negative electrode tab 31 is provided with the second portion 33022. In this way, when the electrode assembly 3 is pressed and heated by the hot pressing end of the hot pressing apparatus, and the second portion 33022 located on the first extension portion 331 and the second extension portion 341 are bonded by being melted by heating, the first portion 33021 located on the first main body portion 330 is not melted, so that the risk that the overlapping portion of the first substrate layer 3301 and the negative electrode tab 31 is blocked by the melting of the first portion 33021 is reduced. The viscous flow temperature refers to the transition temperature of the high polymer from a high elastic state to a viscous flow state, and the temperature reflects the heat deformation resistance of the high polymer. It will be appreciated that if the pores of the first substrate layer 3301 are blocked, the lithium ions released from the positive electrode tab 32 are blocked and cannot be inserted into the negative electrode tab 31 through the first separator 33, so that lithium precipitation occurs.
The difference in viscous flow temperature between the first portion 33021 and the second portion 33022 may be a difference caused by different percentages by mass of the same components, a difference caused by different hot melt molecular weights of the first portion 33021 and the second portion 33022, or a difference caused by different types of hot melt polymers of the first portion 33021 and the second portion 33022. In this embodiment, the difference in viscous flow temperature between the first portion 33021 and the second portion 33022 is caused by the different mass percentages occupied by the same constituent components.
In some embodiments, the second portion 33022 includes a hot melt polymer, a binder, and inorganic particles, the sum of the mass percent of the hot melt polymer, the mass percent of the binder, and the mass percent of the inorganic particles being 100%, satisfying at least one of the following conditions:
(1) The mass percentage of the hot melt polymer is 50% -97%;
the higher the content of the hot-melt polymer, the better the fluidity of the hot-melt polymer when it is converted into a viscous state, and the easier the adhesion when it is bonded. When the mass percentage of the hot-melt polymer satisfies the above relation, the bonding reliability is improved.
(2) The mass percentage of the binder is 2% -49%;
(3) The mass percentage of the inorganic matters is 1-10%, and the porosity of the inorganic particles of the inorganic matters is more than 50%.
The higher the mass percentage of the inorganic material and the higher the porosity, the more advantageous it is to improve the transport properties of lithium ions, i.e. the lithium ions can better pass through the first portion 33021.
In some embodiments, the hot melt polymer comprises one or more of ethylene vinyl acetate copolymer (EVA resin for short), polyethylene oxide (PEO for short). The binder may be, for example, polyvinylidene fluoride (PVDF for short), although other binders are also possible. The inorganic material may be one or more of silica, alumina, zirconia or boehmite, although others are also possible. The porosity of the inorganic particles of the mineral can be measured by the BET (Brunauer-Emmett-Teller) law.
Likewise, the third surface 34011 may be provided with the second hot melt adhesive layer 3402 throughout the entire surface; the second hot melt adhesive layer 3402 may be disposed only in a partial area, for example, the third surface 34011 may be disposed on the second extending portion 341 and/or the fourth extending portion 342 in the area where the second hot melt adhesive layer 3402 is disposed, which may be more desirable.
In some embodiments, the third surface 34011 is provided with a second hot-melt adhesive layer 3402 on the whole surface, the second hot-melt adhesive layer 3402 includes a third portion 34021 and a fourth portion 34022, along the thickness direction Z of the electrode assembly 3, the projection of the third portion 34021 is located in the projection of the negative electrode tab 31, the projection of the fourth portion 34022 is located outside the projection of the negative electrode tab 31, the viscous flow temperature of the third portion 34021 is C, the viscous flow temperature of the fourth portion 34022 is D, and 10 ℃ < C-D is less than or equal to 120 ℃. That is, in the thickness direction Z of the electrode assembly 3, the second separator 34 is provided with the third portion 34021 for the region overlapping with the negative electrode tab 31, and the region where the second separator 34 does not contact with the negative electrode tab 31 is provided with the fourth portion 34022. Thus, the third portion 34021 located on the second main body 340 does not melt when the hot-pressing head of the hot-pressing apparatus presses and heats the electrode assembly 3, which reduces the risk that the overlapping portion of the second base material layer 3401 and the negative electrode tab 31 blocks the surface micropores due to the melting of the third portion 34021, and facilitates the lithium ions of the positive electrode tab 32 to be smoothly inserted into the negative electrode tab 31 through the second separator 34, thereby improving the stability of the electrode assembly 3.
Also, the reason for the difference in viscosity flow temperature between the third portion 34021 and the fourth portion 34022 may refer to the reason for the difference in viscosity flow temperature between the first portion 33021 and the second portion 33022, which will not be described herein.
In some embodiments, the fourth portion 34022 is the same as the second portion 33022, i.e., the fourth portion 34022 comprises a hot melt polymer, a binder, and inorganic particles, the sum of the mass percent of the hot melt polymer, the mass percent of the binder, and the mass percent of the inorganic particles being 100%, satisfying at least one of the following conditions:
(1) The mass percentage of the hot melt polymer is 50% -97%;
the higher the content of the hot-melt polymer, the better the fluidity of the hot-melt polymer when it is converted into a viscous state, and the easier the adhesion when it is bonded. When the mass percentage of the hot-melt polymer satisfies the above relation, the bonding reliability is improved.
(2) The mass percentage of the binder is 2% -49%;
(3) The mass percentage of the inorganic matters is 1-10%, and the porosity of the inorganic particles of the inorganic matters is more than 50%.
The higher the mass percentage of the inorganic material and the higher the porosity, the more advantageous it is to improve the transport properties of lithium ions, i.e. the lithium ions can better pass through the first portion 33021. When the mass percent of the inorganic substance and the porosity of the inorganic particles satisfy the above relationship, the effect of the inorganic substance can be exerted well.
In some embodiments, the first active material layer 312 includes a first active portion 3121 beyond the edge of the positive electrode tab 32, the second active material layer 313 includes a second active portion 3131 beyond the edge of the positive electrode tab 32, the first active portion 3121 is bonded to the first hot melt adhesive layer 3302, and the second active portion 3131 is bonded to the second hot melt adhesive layer 3402. In this way, the risk of both the first active portion 3121 and the second active portion 3131 being separated from the anode current collector 311 by an external force can be reduced, contributing to an improvement in the stability of the anode tab 31.
Further, the first active material layer 312 further includes a third active portion 3122 beyond the edge of the positive electrode tab 32, the third active portion 3122 and the first active portion 3121 are respectively located at two sides of the positive electrode tab 32, the second active material layer 313 further includes a fourth active portion 3132 beyond the edge of the positive electrode tab 32, the fourth active portion 3132 and the second active portion 3131 are respectively located at two sides of the positive electrode tab 32, the third active portion 3122 is bonded to the first hot melt adhesive layer 3302, and the fourth active portion 3132 is bonded to the second hot melt adhesive layer 3402. In this way, the risk of both the third active portion 3122 and the fourth portion 34022 being separated from the anode current collector 311 by an external force can be reduced, contributing to further improving the stability of the anode tab 31.
In some embodiments, the secondary battery 1 further includes a positive electrode tab 4 and a negative electrode tab 5, wherein one ends of the positive electrode tab 4 and the negative electrode tab 5 are connected to the electrode assembly 3, and the other ends of the positive electrode tab 4 and the negative electrode tab 5 extend out of the case 2. The positive electrode tab 4 is connected to the positive electrode tab 32 of the electrode assembly 3, and the negative electrode tab 5 is connected to the negative electrode tab 31 of the electrode assembly 3. The positive electrode lug 4 and the negative electrode lug 5 are used for connecting power supply equipment.
The secondary battery 1 provided by the embodiment of the application comprises a shell 2 and an electrode assembly 3, wherein the electrode assembly 3 is accommodated in the shell 2; in the thickness direction Z of the electrode assembly 3, the electrode assembly 3 includes a positive electrode tab 32, a negative electrode tab 31, a first separator 33, and a second separator 34 that are stacked, the negative electrode tab 31 being located between the first separator 33 and the second separator 34; the first separator 33 includes a first substrate layer 3301, the first substrate layer 3301 includes opposing first and second surfaces 33011, 33012, the second separator 34 includes a second substrate layer 3401, the second substrate layer 3401 includes opposing third and fourth surfaces 34011, 34012, the first and third surfaces 33011, 34011 each face the negative electrode tab 31, and the second and fourth surfaces 33012, 34012 each face the positive electrode tab 32; in a direction perpendicular to the thickness direction Z of the electrode assembly 3, the negative electrode tab 31 exceeds the positive electrode tab 32, the first separator 33 includes a first main body portion 330 facing the negative electrode tab 31 and a first extension portion 331 connected to the first main body portion 330 and exceeding the negative electrode tab 31, the second separator 34 includes a second main body portion 340 facing the negative electrode tab 31 and a second extension portion 341 connected to the second main body portion 340 and exceeding the negative electrode tab 31, the first extension portion 331 and the second extension portion 341 being located on the same side of the negative electrode tab 31; the first diaphragm 33 includes a first hot melt adhesive layer 3302 disposed on the first surface 33011 and a first ceramic layer 3303 disposed on the second surface 33012, the first hot melt adhesive layer 3302 being located at least at the first extension 331, the first ceramic layer 3303 being located at the first body portion 330 and the first extension 331; the second diaphragm 34 includes a second hot melt adhesive layer 3402 disposed on the third surface 34011 and a second ceramic layer 3403 disposed on the fourth surface 34012, where the second hot melt adhesive layer 3402 is located at least on the second extension 341, and the second ceramic layer 3403 is located on the second main body 340 and the second extension 341; the first extension 331 and the second extension 341 located at both sides of the negative electrode tab 31 of the outermost layer of the electrode assembly 3 are bonded by the first hot melt adhesive layer 3302 and the second hot melt adhesive layer 3402. Thus, the bonding position between the first extending part 331 and the second extending part 341 is favorable to form a closed area, the risk that the falling material falls out of the closed area when the side, exceeding the positive electrode plate 32, of the negative electrode plate 31 is subjected to external force is reduced, the risk that the falling material is short-circuited with the positive electrode plate 32 is favorable to be reduced, the stability of the electrode assembly 3 is improved, and the safety performance of the secondary battery 1 is favorable to be improved. Meanwhile, the first ceramic layer 3303 on the first extension part 331 and the second ceramic layer 3403 on the second extension part 341 are beneficial to preventing the first extension part 331 and the second extension part 341 from deformation when being subjected to external force, so that the strength of the first diaphragm 33 and the second diaphragm 34 is enhanced, the risk that the part of the negative electrode pole piece 31 exceeding the positive electrode pole piece 32 is subjected to external force is reduced, and the stability of the electrode assembly 3 is further improved.
Another embodiment of the present application provides an electronic device, including the secondary battery 1 of the above embodiment, where the secondary battery 1 provides electric energy to the electronic device. Which may be any electronic device known in the art. For example, electronic devices include, but are not limited to, notebook computers, pen-input computers, mobile computers, electronic book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, video recorders, liquid crystal televisions, hand-held cleaners, portable CD-players, mini-compact discs, transceivers, electronic organizers, calculators, memory cards, portable audio recorders, radios, backup power supplies, motors, automobiles, motorcycles, mopeds, bicycles, lighting fixtures, toys, game consoles, timepieces, power tools, flashlights, cameras, home-use large-scale storage batteries, lithium ion capacitors, and the like.
Referring to fig. 7-9, another embodiment of the present application provides a method for preparing a secondary battery, which includes the following steps:
step 201: preparing an electrode assembly, wherein the electrode assembly comprises a positive electrode plate, a negative electrode plate and a diaphragm which are arranged in a superposed manner, the diaphragm comprises a first diaphragm and a second diaphragm, and the negative electrode plate is positioned between the first diaphragm and the second diaphragm;
In some embodiments, referring to fig. 8, step S201 includes the following steps:
step S2011: preparing at least two diaphragms, wherein the at least two diaphragms comprise a first diaphragm and a second diaphragm;
in some embodiments, referring to fig. 9, step S2011 includes the following steps:
step S20111: providing a separation substrate, a hot melt raw material and a ceramic raw material;
step S20112: uniformly mixing the hot melt collagen materials to obtain first mixed slurry;
the hot melt collagen is the composition of the hot melt adhesive layer, such as the hot melt polymer, the binder and the inorganic matters mentioned in the above embodiments, and the several composition components are mixed together according to a certain mass percentage, so as to obtain the hot melt collagen.
Step S20113: uniformly mixing the ceramic raw materials to obtain second mixed slurry;
the ceramic raw material comprises one or more of silicon dioxide, aluminum oxide, zirconium dioxide or boehmite in the embodiment, and is obtained by stirring and mixing according to the weight of the required ceramic raw material components.
Step S20114: and coating the first mixed slurry on the first coating surface of the isolating substrate, coating the second mixed slurry on the second coating surface of the isolating substrate layer, and drying to obtain the diaphragm.
The drying treatment is to dry the excess water so that the first mixed slurry and the second mixed slurry can be adhered to the surface of the separator substrate, thereby obtaining the separator.
Step S2012: providing a positive electrode plate and a negative electrode plate;
step S2013: and superposing the positive electrode plate, the negative electrode plate, the first diaphragm and the second diaphragm to finally form an electrode assembly, wherein the negative electrode plate is positioned between the first diaphragm and the second diaphragm.
Step 202: hot-pressing the electrode assembly to bond the first hot-melt adhesive layer and the second hot-melt adhesive layer, so that the first diaphragm and the second diaphragm jointly wrap the negative electrode plate;
step S203: providing a packaging bag, placing the electrode assembly in the packaging bag, and hot-pressing and edge-sealing the packaging bag;
step S204: and injecting electrolyte into the packaging bag, and then forming and standing.
For the convenience of the reader to understand the technical solution of the present application, the following is an experimental comparison performed by the inventor on a plurality of secondary batteries manufactured by the hot melt adhesive layer and the ceramic layer under different thickness dimensions, and is specifically as follows:
example 1
Preparation of secondary battery
(1) Electrode assembly
1.1 preparation of a separator:
preparing ceramic raw materials: uniformly mixing 95% wt of silicon dioxide (particle size 50-150nm, porosity 70% -80%) and 5% wt of sodium carboxymethylcellulose into slurry 1 by using deionized water, wherein the solid content of the slurry is 40%;
preparing hot melt collagen: uniformly mixing 80% wtEVA (VA content 40-60%, viscous flow point-60 ℃), 15% polyvinylidene fluoride and 5% silicon dioxide (particle size 50-150nm, porosity 50-80%) into slurry 2 with deionized water, wherein the solid content of the slurry is 20%;
coating the slurry 1 on a polyethylene substrate (with the thickness of 5 um) by adopting gravure coating, wherein the coating thickness is 1.5um, the coating surface is marked as a B surface, coating the slurry 2 on the polyethylene substrate by repeatedly using gravure coating, the coating thickness is 4um, the coating surface is the other surface of the B surface, marked as an A surface, drying to obtain a finished diaphragm, and marking as a first diaphragm, wherein the dried first diaphragm forms a hot melt adhesive layer, a substrate layer and a ceramic layer;
repeating the steps to obtain a second diaphragm;
1.2 providing a positive electrode sheet and a negative electrode sheet, stacking the positive electrode sheet, the negative electrode sheet, the first separator and the second separator, the negative electrode sheet being positioned between the first separator and the second separator, thereby forming an electrode assembly.
(2) And placing the electrode assembly at a hot-pressing end of a hot-pressing instrument for hot-pressing shaping, so that the hot melt adhesive layers of the first diaphragm and the second diaphragm are mutually bonded. The thickness of the negative electrode plate is 150 mu m, and the length L of the first diaphragm and the second diaphragm exceeding the negative electrode plate is 0.8mm.
(3) And providing a packaging bag, placing the electrode assembly in the packaging bag, and hot-pressing and edge-sealing the packaging bag.
(4) And injecting electrolyte into the packaging bag, then forming and standing, and finally completing the preparation of the secondary battery.
Examples 2 to 6
The difference from example 1 is that the length L of the hot melt adhesive layer, the ceramic layer, the first separator and the second separator beyond the negative electrode tab and the thickness of the negative electrode tab are different.
The main body portion (including the first main body portion and the second main body portion) of the separator of the secondary battery in example 6 was not coated with the slurry 2, and the main body portion (including the first main body portion and the second main body portion) of the separator of the secondary battery in example 5 was coated with the slurry 2.
Table 1 comparison of the thickness of the hot melt adhesive layers and ceramic layers of examples 1-6
Figure BDA0004133283130000171
Figure BDA0004133283130000181
Table 2 table of experiments performed by heating, drop test, lithium evolution test of secondary batteries of examples 1 to 6 in full charge state
Figure BDA0004133283130000182
/>
In the above experiments, the comparative example was to use a conventional secondary battery. The passing condition of the constant temperature heating experiment in the full charge state is that the secondary battery does not fire or explode in the constant temperature heating time. The passing condition of the drop test is that 1.5m, 1.8m and 2.0m in the drop test represent the drop height of the secondary battery, the test condition of the drop test is 6-face 4-angle 5-wheel, namely, each secondary battery drops by six-face and four-corner 5-wheel repetition respectively, and the secondary battery is not damaged, does not leak and has voltage drop less than 50 mV. In the lithium analysis test, 1.5C, 1.6C and 1.7C represent that the secondary batteries were charged at different charging rates, respectively.
From the experimental results of comparative examples and examples 1 to 6, it was found that the secondary battery was high in yield in the experiment of constant temperature heating in the full charge state, indicating that the provision of the ceramic layer was advantageous for improving the thermal stability of the secondary battery. As can be seen from the results of the drop test experiments, the secondary battery provided with the hot melt adhesive layer and the ceramic layer has a higher passing rate, which indicates that the provision of the hot melt adhesive layer helps to improve the connection firmness between the separators, thereby improving the passing rate of the secondary battery.
From the experimental results of examples 1 and 2, it is understood that the greater the thickness of the ceramic layer, the better the thermal stability of the secondary battery, but increasing the thickness of the ceramic layer affects the adhesive effect of the hot melt adhesive layer.
From comparison of the experimental results of example 2 and example 3, it is apparent that increasing the thickness of the hot melt adhesive layer is more advantageous for bonding between the separators, more advantageous for improving the thermal stability of the secondary battery, and also advantageous for improving the bonding firmness between the separators, and improving the reliability of the secondary battery.
From comparison of the experimental results of example 3 and example 4, the higher the passing rate of the drop test of the secondary battery of example 4, the thinner the thickness of the negative electrode tab, which is beneficial to improving the bonding firmness of the hot melt adhesive layer and improving the reliability of the secondary battery.
As is apparent from comparison of the experimental results of example 4 and example 5, the pass rate of the secondary battery of example 5 was higher than that of example 4 in the drop test experiment, indicating that the greater the length L of the separator beyond the negative electrode tab, the more favorable the firm bonding between the separators, thereby improving the reliability of the secondary battery.
From comparison of the experimental results of example 5 and example 6, it is apparent that in the lithium precipitation experiment, the secondary battery of example 6 does not have a lithium precipitation phenomenon, which indicates that the main body portion of the separator is not coated with high hot melt delamination, which is beneficial to lithium ion transmission, and reduces the risk of lithium precipitation of the secondary battery.
The foregoing description is only of embodiments of the present application, and is not intended to limit the scope of the patent application, and all equivalent structures or equivalent processes using the descriptions and the contents of the present application or other related technical fields are included in the scope of the patent application.

Claims (14)

1. A secondary battery includes a case and an electrode assembly received in the case;
in the thickness direction of the electrode assembly, the electrode assembly comprises a positive electrode plate, a negative electrode plate, a first diaphragm and a second diaphragm which are stacked, wherein the negative electrode plate is positioned between the first diaphragm and the second diaphragm;
The first separator comprises a first substrate layer, the first substrate layer comprises a first surface and a second surface which are opposite, the second separator comprises a second substrate layer, the second substrate layer comprises a third surface and a fourth surface which are opposite, the first surface and the third surface are opposite to the negative electrode pole piece, and the second surface and the fourth surface are opposite to the positive electrode pole piece;
the method is characterized in that: in a direction perpendicular to a thickness direction of the electrode assembly, the negative electrode tab exceeds the positive electrode tab, the first separator includes a first body portion facing the negative electrode tab and a first extension portion connected to the first body portion and exceeding the negative electrode tab, the second separator includes a second body portion facing the negative electrode tab and a second extension portion connected to the second body portion and exceeding the negative electrode tab, the first extension portion and the second extension portion being located on the same side of the negative electrode tab;
the first diaphragm comprises a first hot melt adhesive layer arranged on the first surface and a first ceramic layer arranged on the second surface, the first hot melt adhesive layer is at least positioned on the first extension part, and the first ceramic layer is positioned on the first main body part and the first extension part; the second diaphragm comprises a second hot melt adhesive layer arranged on the third surface and a second ceramic layer arranged on the fourth surface, the second hot melt adhesive layer is at least positioned at the second extension part, and the second ceramic layer is positioned at the second main body part and the second extension part; the first extending part and the second extending part which are positioned at two sides of the negative electrode piece of the outermost layer of the electrode assembly are bonded through the first hot melt adhesive layer and the second hot melt adhesive layer.
2. The secondary battery according to claim 1, wherein the first separator further comprises a third extension portion connected to the first body portion and beyond the negative electrode tab, the third extension portion being located at opposite ends of the first body portion from the first extension portion, the second separator further comprises a fourth extension portion connected to the second body portion and beyond the negative electrode tab, the fourth extension portion being located at opposite ends of the second body portion from the second extension portion, and the third extension portion and the fourth extension portion located at both sides of the negative electrode tab of the outermost layer of the electrode assembly are bonded by the first and second hot melt adhesives layers.
3. The secondary battery according to claim 1, wherein the first hot melt adhesive layer comprises a first portion and a second portion, a projection of the first portion is located in a projection of the negative electrode tab, a projection of the second portion is located outside the projection of the negative electrode tab, a viscous flow temperature of the first portion is a, and a viscous flow temperature of the second portion is B, in a thickness direction of the electrode assembly, so that 10 ℃ < a-B is less than or equal to 120 ℃.
4. The secondary battery according to claim 3, wherein the second hot-melt adhesive layer comprises a third portion and a fourth portion, a projection of the third portion is located in a projection of the negative electrode tab, a projection of the fourth portion is located outside the projection of the negative electrode tab, a viscous flow temperature of the third portion is C, and a viscous flow temperature of the fourth portion is D, which satisfies 10 ℃ < C-d.ltoreq.120℃.
5. The secondary battery according to claim 3, wherein the first portion includes a hot-melt polymer, a binder, and inorganic particles, and a sum of the mass percent of the hot-melt polymer, the mass percent of the binder, and the mass percent of the inorganic particles is 100%, at least one of the following conditions being satisfied:
(1) The mass percentage of the hot melt polymer is 50% -97%;
(2) The mass percentage of the binder is 2% -49%;
(3) The mass percentage of the inorganic matters is 1-10%, and the porosity of the inorganic particles of the inorganic matters is more than 50%.
6. The secondary battery according to claim 5, wherein at least one of the following conditions is satisfied:
(1) The hot melt polymer comprises ethylene-vinyl acetate copolymer and/or polyethylene oxide;
(2) The binder comprises polyvinylidene fluoride;
(3) The inorganic substance may be at least one of silica, alumina, zirconia, or boehmite.
7. The method according to claim 1A secondary battery is characterized in that the thickness of the first substrate layer is T 1 The thickness of the first ceramic layer is T 2 The thickness of the first hot melt adhesive layer is T 3 The thickness of the second substrate layer is T 4 The thickness of the second ceramic layer is T 5 The thickness of the second hot melt adhesive layer is T 6 The thickness of the negative electrode plate is t, and at least one of the following conditions is satisfied:
(1)3μm≤T 1 ≤9μm；
(2)1μm≤T 2 ≤5μm；
(3)0.5μm＜T 3 ≤6μm；
(4)80μm≤t≤300μm；
(5)3μm≤T 4 ≤9μm；
(6)1μm≤T 5 ≤5μm；
(7)0.5μm＜T 6 ≤6μm。
8. the secondary battery according to claim 7, wherein at least one of the following conditions is satisfied:
(1)1.5μm≤T 3 ≤5μm；
(2)1μm≤T 2 ≤2μm；
(3)80μm≤t≤100μm。
9. the secondary battery according to claim 1, wherein the negative electrode tab has a thickness t, and the first extension and/or the second extension has a length L in a direction perpendicular to the thickness direction of the electrode assembly, as viewed in the thickness direction of the electrode assembly, satisfying l.gtoreq.0.5 mm, and l.gtoreq.5 t.
10. The secondary battery according to claim 1, wherein the negative electrode tab includes a negative electrode current collector including a first face adjacent to the first separator and a second face adjacent to the second separator in a thickness direction of the electrode assembly, the first face being provided with the first active material layer, and the second face being provided with the second active material layer, wherein the first active material layer includes a first active portion beyond an edge of a positive electrode tab, the second active material layer includes a second active portion beyond an edge of a positive electrode tab, the first active portion is bonded with the first hot melt adhesive layer, and the second active portion is bonded with the second hot melt adhesive layer.
11. An electronic device comprising the secondary battery according to any one of claims 1 to 10.
12. A method for manufacturing a secondary battery, applied to the secondary battery as claimed in any one of claims 1 to 10, comprising:
preparing an electrode assembly, wherein the electrode assembly comprises a positive electrode plate, a negative electrode plate and a diaphragm which are arranged in a superposed manner, the diaphragm comprises a first diaphragm and a second diaphragm, and the negative electrode plate is positioned between the first diaphragm and the second diaphragm;
hot-pressing the electrode assembly to bond the first hot-melt adhesive layer and the second hot-melt adhesive layer, so that the first diaphragm and the second diaphragm jointly wrap the negative electrode plate;
providing a packaging bag, placing the electrode assembly in the packaging bag, and hot-pressing and edge-sealing the packaging bag;
and injecting electrolyte into the packaging bag, and then forming and standing.
13. The method of manufacturing according to claim 12, wherein the step of manufacturing the electrode assembly comprises:
preparing at least two diaphragms, wherein the at least two diaphragms comprise a first diaphragm and a second diaphragm;
providing a positive electrode plate and a negative electrode plate;
And superposing the positive electrode plate, the negative electrode plate, the first diaphragm and the second diaphragm to finally form an electrode assembly, wherein the negative electrode plate is positioned between the first diaphragm and the second diaphragm.
14. The method of preparing according to claim 13, wherein the step of preparing at least two separators comprises:
providing a separation substrate, a hot melt raw material and a ceramic raw material;
uniformly mixing the hot melt collagen materials to obtain first mixed slurry;
uniformly mixing the ceramic raw materials to obtain second mixed slurry;
and coating the first mixed slurry on the first coating surface of the isolating substrate, coating the second mixed slurry on the second coating surface of the isolating substrate layer, and drying to obtain the diaphragm.
CN202310262590.4A 2023-03-17 2023-03-17 Secondary battery, preparation method thereof and electronic device Pending CN116345070A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310262590.4A CN116345070A (en) 2023-03-17 2023-03-17 Secondary battery, preparation method thereof and electronic device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310262590.4A CN116345070A (en) 2023-03-17 2023-03-17 Secondary battery, preparation method thereof and electronic device

Publications (1)

Publication Number Publication Date
CN116345070A true CN116345070A (en) 2023-06-27

Family

ID=86888929

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202310262590.4A Pending CN116345070A (en) 2023-03-17 2023-03-17 Secondary battery, preparation method thereof and electronic device

Country Status (1)

Country Link
CN (1) CN116345070A (en)

Similar Documents

Publication Publication Date Title
JP6208945B2 (en) Separator and electrochemical element provided with the same
KR100983161B1 (en) Electrode assembly and secondary battery using the same
JP5976015B2 (en) Separator, method for manufacturing the same, and electrochemical device including the same
JP6575136B2 (en) Solid battery and assembled battery using the same
KR101734328B1 (en) Electrode assembly, Method of manufacturing the same and Electrochemical device comprising the electrode assembly
CN112768784B (en) Electrochemical device and electronic device
KR100754746B1 (en) Organic/inorganic composite separator having porous active coating layer and electrochemical device containing the same
KR20100051710A (en) Battery separator and nonaqueous electrolyte battery
JP6492958B2 (en) Solid battery and assembled battery using the same.
CN110622339B (en) Separator for nonaqueous secondary battery, and method for producing nonaqueous secondary battery
TWI404250B (en) Unit cell for secondary battery having conductive sheet layer and lithium ion secondary battery having the same
CN101409339B (en) Electrode assembly and secondary battery having the same
US20080138699A1 (en) Jelly roll electrode assembly and secondary battery using the assembly
KR20110138718A (en) Pocketed electrode plate, electrode assembly and lithium secondary battery using thereof
KR100908977B1 (en) Electrode Assembly of Secondary Battery
KR100824851B1 (en) Electrode assembly and rechargeable battery with the same
KR101351700B1 (en) Electrode assembly and rechargeable battery with the same
CN114725623A (en) Battery, electronic device, and mobile device
KR20130052406A (en) Separator for electrochemical device and electrochemical device containing the same
JP2006012703A (en) Secondary battery
KR102328527B1 (en) Stack-type electrode assembly with no deflection of the electrode and manufacturing methods thereof
CN114128028A (en) Composite separator for electrochemical device and electrochemical device comprising the same
CN116345070A (en) Secondary battery, preparation method thereof and electronic device
CN115939492A (en) Electrochemical device and electricity utilization device
CN115360477A (en) Separator and 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