CN115275521A - Diaphragm, roll up core and battery - Google Patents

Diaphragm, roll up core and battery Download PDF

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Publication number
CN115275521A
CN115275521A CN202211096160.1A CN202211096160A CN115275521A CN 115275521 A CN115275521 A CN 115275521A CN 202211096160 A CN202211096160 A CN 202211096160A CN 115275521 A CN115275521 A CN 115275521A
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ceramic
particles
lithium
diaphragm
ceramic layer
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徐寒姣
王烽
李素丽
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • 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
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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
    • 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
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/497—Ionic conductivity
    • 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

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Cell Separators (AREA)

Abstract

The invention relates to the technical field of lithium ion batteries, and provides a diaphragm, a winding core containing the diaphragm, and a battery containing the diaphragm or the winding core. The diaphragm comprises a substrate, wherein the substrate is divided into an arc area and a flat area; at least one surface of the circular arc area is provided with a first ceramic layer, and at least one surface of the flat area is provided with a second ceramic layer; wherein the first ceramic layer comprises ion conductor particles and first ceramic particles; the ion conductor particles have a median diameter Dv501 andthe median particle diameter Dv502 of the first ceramic particles satisfies:
Figure DDA0003838812270000011
the battery containing the diaphragm avoids the problem that the circular arc area diaphragm blocks holes in a ceramic layer due to a binder in the charging process, promotes the transmission of lithium ions, and further effectively solves the problem of black spot lithium precipitation.

Description

Diaphragm, roll up core and battery
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a diaphragm, a winding core containing the diaphragm and a battery containing the diaphragm or the winding core.
Background
Lithium ion batteries are clean energy sources with small volume, light weight and high energy storage ratio, and are widely used in various fields at present. The lithium ion battery comprises a winding type battery cell, the winding type battery cell is an electrode assembly formed by winding a positive plate, a negative plate and a diaphragm after the roller plates through a winding machine, and the positive plate and the negative plate are separated by the diaphragm in the winding process.
In a winding type battery cell, the battery cell can be divided into an unbent flat area and a bent arc area. The electrode plate of the winding type battery cell expands in the charging process, internal stress is generated in the battery cell, the flat area can expand outwards in the thickness direction of the battery cell, the internal stress is low, and the internal stress of the arc area is difficult to release compared with that of the flat area due to the stable structure, so that the arc area generates larger internal stress when the expansion of the electrode plate is inhibited; due to internal stress extrusion, the diaphragm in the arc area of the battery cell is blocked by a glue layer, so that lithium ion transmission is blocked, and further, black spot lithium precipitation is generated.
Therefore, it is of great significance to develop a battery separator capable of solving the problem of black spot lithium deposition.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provide a separator, a winding core containing the separator and a battery containing the separator or the winding core. Through set up different functional areas (circular arc district and flat area) on the diaphragm, add in the diaphragm coating in circular arc district than first ceramic particle diameter bigger, can conduct the ionic ion's ion conductor granule fast, make the battery that contains this diaphragm avoid circular arc district diaphragm to take place the problem of binder stifled hole in the ceramic layer in charging process, promote lithium ion transmission, and then effectively solve the problem that the lithium was analysed to the black spot.
The inventor of the invention researches and discovers that the condition of black spot lithium precipitation can be effectively inhibited by adding ion conductor particles which have larger particle size than the first ceramic particles and can rapidly conduct lithium ions into the diaphragm ceramic coating in the arc area. On one hand, the ion conductor particles with larger particle size can be used as supporting points to increase the hole-protecting capacity of the diaphragm in the circular arc area and prevent the risk of blocking the holes by the binder in the ceramic layer due to internal stress extrusion; on the other hand, the ion conductor particles can accelerate the lithium ion transmission capacity of the arc area so as to make up for the defect that the lithium ion transmission rate at the arc area is slow due to internal stress extrusion.
In order to achieve the above object, a first aspect of the present invention provides a separator including a substrate divided into a circular arc region and a flat region; at least one surface of the circular arc area is provided with a first ceramic layer, and at least one surface of the flat area is provided with a second ceramic layer; wherein the first ceramic layer comprises ion conductor particles and first ceramic particles; the ion conductor particles have a median diameter Dv50 1 And the median particle diameter Dv50 of the first ceramic particles 2 Satisfies the following conditions:
Figure BDA0003838812250000021
the second aspect of the invention provides a winding core, which is a winding structure formed by a first diaphragm, a first pole piece, a second diaphragm and a second pole piece which are sequentially stacked, wherein the first diaphragm and the second diaphragm are diaphragms in the first aspect of the invention; wherein, along the stretching direction of the winding core, the width of the arc area is not more than the bending part of the winding structure, and the width of the flat area is not less than the non-bending part of the winding structure.
In a third aspect, the present invention provides a battery comprising at least one of the separator according to the first aspect of the present invention and the jelly roll according to the second aspect of the present invention.
The invention adopts the technical scheme and has the following beneficial effects:
according to the invention, the different functional areas (the arc area and the flat area) are arranged on the diaphragm, and the ion conductor particles which have larger particle size than the first ceramic particles and can rapidly conduct lithium ions are added into the diaphragm coating of the arc area, so that the problem that the pore is blocked by a binder in a ceramic layer of the diaphragm of the arc area is avoided in the charging process of the battery containing the diaphragm, the lithium ion transmission is promoted, and the problem of black spot lithium precipitation is effectively solved.
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, such ranges or values should be understood to encompass values close to these ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
Drawings
FIG. 1 is a schematic view of a roll core structure according to an embodiment of the present invention.
Fig. 2 is a schematic view of a roll core structure according to an embodiment of the present invention.
Fig. 3 shows a schematic view of the structure of the separator of the present invention in the width direction (both ends are not shown).
Description of the reference numerals
101: a circular arc region; 102: a flat region; 103: a positive electrode; 104: and a negative electrode.
Detailed Description
The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
Unless defined otherwise, all scientific and technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
The invention provides a diaphragm, which comprises a substrate, wherein the substrate is divided into an arc area and a flat area; at least one surface of the circular arc area is provided with a first ceramic layer, and at least one surface of the flat area is provided with a second ceramic layer; wherein the first ceramic layer comprises ion conductor particles and first ceramic particles; the ion conductor particles have a median diameter Dv50 1 And the median particle diameter Dv50 of the first ceramic particles 2 Satisfies the following conditions:
Figure BDA0003838812250000041
in the present invention, dv50 is used to indicate the particle size corresponding to 50% of the volume distribution of the particles, i.e. particles having a size greater than 50% of the total number of particles and particles having a size less than 50% of the total number of particles.
In one example, one surface of the circular arc region is provided with a first ceramic layer, at least one surface of the flat region is provided with a second ceramic layer, and the first ceramic layer and the second ceramic layer are in a horizontal plane.
In one example, two opposite surfaces of the circular arc region are provided with a first ceramic layer, and two opposite surfaces of the flat region are provided with a second ceramic layer.
When diaphragm and pole piece winding form the core structure, the different regions of diaphragm substrate can present two kinds of states: the membrane substrate may have a curved region and an unbent region, corresponding to the curved state and the unbent state. In the present invention, the "arc region" may be a portion of the bending region of the diaphragm substrate including the inflection point of the bending portion, or the "arc region" may be the entire bending region of the diaphragm substrate. The "flat region" may be an entire unbent region and a partially bent region of the separator substrate, and the partially bent region does not include a bending point, or may be an entire unbent region of the separator substrate. And the inflection point of the bending part is the intersection point of the central line of the winding core and the bending area.
The inventor of the invention finds that the lithium ion transport capability can be improved by adding the ion conductor particles into the first ceramic layer in the arc area, so that the black spot lithium deposition in the arc area is relieved. The particle size of increase ion conductor granule makes the particle size difference of ion conductor granule and first ceramic granule great to make and form more pore structure between granule and the granule, and under the support of bigger granule, can avoid because roll up core circular arc district stress concentration and lead to the diaphragm hole to be blocked up, hinder lithium ion transmission, and then lead to the condition emergence of the regional black spot lithium deposition of roll core bending. However, if the particle size of the first ceramic particles is made larger than that of the ion conductor particles, although the pore-preserving capability of the membrane in the arc region is enhanced to some extent, the transport capability of the first ceramic particles is inferior to that of the ion conductor particles, and lithium ions are transported more slowly, so that the problem of black spot lithium deposition cannot be solved.
In one example, the separator substrate is a porous substrate, and a separator substrate conventionally used in the art may be selected.
Illustratively, the porous substrate is selected from at least one of polyethylene, polypropylene, multi-layer polyethylene polypropylene, polyethylene polypropylene blend, polyimide, polyetherimide, polyamide, meta-aramid, para-aramid, and meta-para-blended aramid.
In a preferred embodiment, as shown in fig. 1, the arc region 101 is the entire curved region of the diaphragm substrate, and the flat region 102 is the entire unbent region of the diaphragm substrate.
In order to better solve the problem of lithium deposition from battery black spots, one or more technical characteristics of the battery black spots can be further optimized.
Illustratively, the
Figure BDA0003838812250000051
The ratio of (a) may be 0.01, 0.05, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.
In one example, the Dv50 is 1 And said Dv50 2 Satisfies the following conditions:
Figure BDA0003838812250000052
preferably, said Dv50 1 And said Dv50 2 Satisfies the following conditions:
Figure BDA0003838812250000053
in one example, the ion conductor particles have a Dv50 1 Is 0.1 μm to 10 μm.
Illustratively, the Dv50 of the ion conductor particle 1 It may be 0.1. Mu.m, 0.5. Mu.m, 1. Mu.m, 2. Mu.m, 3. Mu.m, 4. Mu.m, 5. Mu.m, 6. Mu.m, 7. Mu.m, 8. Mu.m, 9. Mu.m and 10. Mu.m.
Preferably, the first and second liquid crystal display panels are,dv50 of the ion conductor particle 1 Is 1 μm to 9 μm, more preferably 2 μm to 8 μm.
In one example, the Dv50 of the first ceramic particle 2 Is 0.01-8 μm.
Illustratively, the Dv50 of the first ceramic particle 2 It may be 0.01. Mu.m, 0.5. Mu.m, 1. Mu.m, 2. Mu.m, 3. Mu.m, 4. Mu.m, 5. Mu.m, 6. Mu.m, 7. Mu.m, or 8. Mu.m.
Preferably, the Dv50 of the first ceramic particle 2 Is 0.05 μm to 6 μm, more preferably 0.1 μm to 4 μm.
In an example, the mass ratio of the ion conductor particles to the first ceramic particles is (0.1-10): 1, and can be, for example, 0.1: 1, 0.5, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10.
Preferably, the mass ratio of the ion conductor particles to the first ceramic particles is (1-5): 1.
In one example, the first ceramic layer has a thickness of 0.5 μm to 20 μm, and may be, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm.
Preferably, the thickness of the first ceramic layer is 1 μm to 10 μm.
In one example, the second ceramic layer has a thickness of 0.5 μm to 20 μm, and may be, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm.
Preferably, the thickness of the second ceramic layer is 1 μm to 10 μm.
In one example, the ion conductor particles are lithium-containing inorganic salts.
Illustratively, the lithium-containing inorganic salt is selected from at least one of lithium phosphate, lithium tantalate, lithium zirconate, lithium titanium phosphate, lithium nitride, lithium lanthanum titanate, lithium aluminum titanium phosphate, and lithium germanium thiophosphate.
In one example, the first ceramic layer includes ion conductor particles, first ceramic particles, and a first binder, and the content of the ion conductor particles is 30 to 70wt%, the content of the first ceramic particles is 30 to 70wt%, and the content of the first binder is 0.01 to 10wt%, based on the total mass of the first ceramic layer.
In one example, the second ceramic layer includes second ceramic particles and a second binder, and the content of the second ceramic particles is 90 to 99.9wt% and the content of the second binder is 0.01 to 10wt% based on the total mass of the second ceramic layer.
In one example, the Dv50 of the second ceramic particle 3 Is 0.01-10 μm.
Illustratively, the Dv50 of the first ceramic particle 3 It may be 0.01. Mu.m, 0.5. Mu.m, 1. Mu.m, 2. Mu.m, 3. Mu.m, 4. Mu.m, 5. Mu.m, 6. Mu.m, 7. Mu.m, 8. Mu.m, 9. Mu.m, or 10. Mu.m.
In an example, the first ceramic particles and the second ceramic particles are each independently selected from at least one of a metal oxide, an inorganic metal salt, a metal nitride, and an inorganic ceramic solid state electrolyte.
Illustratively, the metal oxides include, but are not limited to, aluminum oxide, magnesium oxide, calcium oxide, titanium dioxide, silicon dioxide, zirconium dioxide, tin dioxide, boehmite, and zinc oxide.
Illustratively, the inorganic metal salts include, but are not limited to, barium sulfate, calcium carbonate, and magnesium sulfate.
Illustratively, metal nitrides include, but are not limited to, tungsten nitride, silicon carbide, boron nitride, aluminum nitride, titanium nitride, and magnesium nitride.
Illustratively, the inorganic ceramic solid electrolyte includes, but is not limited to, at least one of NASICON-structured, perovskite-structured, anti-perovskite-structured, thio-LISICON-structured, and garnet-structured solid electrolyte particles.
In one example, the first ceramic particles and the second ceramic particles are each independently selected from one or more of alumina, magnesia, silica, titania, zirconia, zinc oxide, barium sulfate, boron nitride, aluminum nitride, magnesium nitride, tin dioxide, magnesium hydroxide, boehmite, and calcium carbonate.
In the present invention, the first ceramic particles and the second ceramic particles may be the same or different.
In one example, the first binder and the second binder are each independently selected from one or more of a copolymer of vinylidene fluoride-hexafluoropropylene, a copolymer of vinylidene fluoride-trichloroethylene, polystyrene, polyacrylate, polyacrylic acid, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, a copolymer of ethylene-vinyl acetate, polyimide, polyphenylene terephthalamide, a copolymer of acrylonitrile-styrene-butadiene, polyvinyl alcohol, a copolymer of styrene-butadiene, and polyvinylidene fluoride.
In the present invention, the first binder and the second binder may be the same or different.
The second aspect of the invention provides a winding core, which is a winding structure formed by a first diaphragm, a first pole piece, a second diaphragm and a second pole piece which are sequentially stacked, wherein the first diaphragm and the second diaphragm are diaphragms in the first aspect of the invention; wherein, along the stretching direction of the winding core, the width of the arc area is not more than the bending part of the winding structure, and the width of the flat area is not less than the non-bending part of the winding structure.
In the present invention, the first separator and the second separator may be the same or different, and preferably, the first separator and the second separator are the same.
As shown in fig. 1 and 3, the winding core has a winding structure formed by stacking a first separator, a negative electrode sheet 104, a second separator, and a positive electrode sheet 103 in this order. The width of the arc zone 101 is the curvature of the wound structure and the width of the flat zone 102 is the non-curvature of the wound structure along the direction of core stretch.
In the present invention, the width direction of the separator is the same as the direction in which the core is stretched.
The inventors of the present invention have found that, in the winding structure of the winding core, since the inflection point of the bend region is a portion where the internal stress is the largest and black speck lithium deposition is more likely to occur, a certain effect of suppressing black speck lithium deposition can be achieved by adding ion conductor particles having a larger particle diameter than the first ceramic particles and capable of rapidly conducting lithium ions to the first ceramic layer of the separator at the inflection point of the bend region. In order to achieve an effect of more effectively suppressing the black mottling lithium deposition, ion conductor particles having a large particle diameter may be added to the first ceramic layer of the partially bent region separator including the inflection point of the bent portion, or ion conductor particles having a large particle diameter may be added to the first ceramic layer of the entire bent region separator.
In an example, as shown in fig. 2, the arc region 101 is a portion of a membrane bending region and includes a bending inflection point (e.g., a bending location within a black dashed box), and the flat region 102 is a membrane full unbent region and a partial bending region and does not include a bending inflection point.
In the invention, the inflection point of the bending part is the intersection point of the central line of the winding core and the bending area.
In one example, as shown in fig. 1, the arc region 101 is the entire curved region of the diaphragm substrate, and the flat region 102 is the entire unflexed region of the diaphragm substrate.
In one example, the width L of the arc region is
Figure BDA0003838812250000091
Wherein d is the thickness of the winding core.
In the present invention, the core bending region is configured as a semicircular structure having a core thickness d as a diameter, and the arc length of the semicircle is the maximum width of the arc region, but the actual shape of the arc region is not limited to the standard semicircular shape. For example, the structure of the winding core is actually similar to the curvature formed by winding the multilayer cloth, which is not a standard semicircle.
In an example, the minimum width of the circular arc region of 0.01mm refers to the minimum width of the inflection point of the bend that includes the bending region of the diaphragm.
In one example, the maximum width of the arc region
Figure BDA0003838812250000092
Which is the arc length of a semicircle with the core thickness d as the diameter.
The structure of the battery except the winding core can be carried out according to the mode in the field, and the effect of inhibiting black spot lithium deposition can be realized.
In a third aspect of the invention, a battery is provided that includes at least one of the separator according to the first aspect of the invention and the jelly roll according to the second aspect of the invention.
In one example, the battery includes a positive electrode sheet, a negative electrode sheet, a nonaqueous electrolyte solution, and the separator according to the first aspect of the present invention, the separator being disposed between the positive electrode sheet and the negative electrode sheet.
In one example, the battery includes the winding core according to the second aspect of the present invention and a nonaqueous electrolytic solution.
In one example, the positive electrode sheet includes a positive electrode collector and a positive electrode active material layer coated on one or both surfaces of the positive electrode collector.
Illustratively, the positive electrode current collector is a substance having conductivity without causing adverse chemical changes in the secondary battery, including, but not limited to, aluminum alloys, nickel alloys, titanium alloys.
The positive electrode active material layer includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder. The positive electrode active material is not particularly limited, and any of the positive electrode active materials commonly used in the art may be used, and may be, for example, at least one of lithium cobaltate, lithium manganate, lithium nickelate, and lithium nickel cobalt manganese lithium phosphate.
In one example, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one or both surfaces of the negative electrode current collector.
The negative electrode current collector is a substance having conductivity without causing adverse chemical changes in the secondary battery, and may be selected from copper, stainless steel, aluminum, nickel, titanium, carbon cloth, or a composite of the materials.
The negative electrode active material layer includes a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder. The negative electrode active material is not particularly limited, and any of the negative electrode active materials commonly used in the art may be used, and for example, may be at least one of graphite, lithium titanate, and silicon-based negative electrodes.
In one example, the positive electrode conductive agent and the negative electrode conductive agent are independently selected from at least one of conductive graphite, ultrafine graphite, acetylene black, conductive carbon black SP, superconducting carbon black, carbon nanotubes, and conductive carbon fibers.
In one example, the positive and negative electrode binders are independently selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethylcellulose, styrene butadiene rubber, polyurethane, polyvinyl alcohol, polyvinylidene fluoride, and copolymers of vinylidene fluoride-fluorinated olefins.
The nonaqueous electrolytic solution may use any electrolyte commonly used in the art, and is not particularly limited herein.
In the present invention, when terms are distinguished by numbers, for example, "first ceramic layer", "second ceramic layer", etc., the numbers in such expressions are used only for distinguishing purposes and do not indicate a sequential order, and the numerical size of the numbers does not have any limiting effect on the technical solution unless otherwise specified.
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.
The invention is described in detail below with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.
In the following examples and comparative examples, in preparing the slurry of the first ceramic layer and the second ceramic layer, other components were dissolved using a solvent, which may be one or more selected from the group consisting of water, N-methyl-2-pyrrolidone, acetone, tetrahydrofuran, chloroform, dichloromethane, dimethylformamide, and cyclohexane.
Since the separator needs to be dried after coating the slurry, the solvent is volatilized after drying, and thus the quality of the final coating layer does not include the quality of the solvent, and the solvent is omitted in examples and comparative examples.
Example 1
1. Preparation of the separator
(1) Preparing first ceramic layer slurry
Mixing alumina particles (first ceramic particles, dv 50) 2 1 μm) and lithium phosphate (ion conductor particles, dv50 1 3 μm) was mixed with a copolymer of vinylidene fluoride-hexafluoropropylene (first binder) to obtain a first paste layer slurry. Wherein, based on the total mass of the first ceramic layer slurry, the content of the first ceramic particles is 49wt%, the content of the ion conductor particles is 49wt%, and the content of the first binder is 2wt%;
(2) Preparing the second ceramic layer slurry
Mixing alumina particles (second ceramic particles, dv 50) 3 1 μm) and a copolymer of vinylidene fluoride-hexafluoropropylene (second binder) to obtain a second ceramic layer slurry. Wherein, based on the total mass of the second ceramic layer slurry, the content of the second ceramic particles is 98wt%, and the content of the second binder is 2wt%;
(3) Adopting any one of coating processes of gravure coating, dip coating, transfer coating, spraying and the like, performing double-sided coating on the arc area of the diaphragm substrate by using first ceramic slurry, performing double-sided coating on the flat area of the diaphragm substrate by using second ceramic layer slurry, and drying;
wherein the content of the first and second substances,
Figure BDA0003838812250000121
ratio of =0.33;
the width L of the circular arc area is 7.85mm, the thickness of the first ceramic layer is 4 μm, and the thickness of the second ceramic layer is 4 μm.
2. Preparation of positive plate
Mixing the positive electrode active material, the positive electrode conductive agent and the positive electrode binder according to a certain proportion, then adding N-methyl pyrrolidone, stirring and dispersing to prepare positive electrode slurry. In the positive electrode slurry, the solid component contained 97.2wt% of Lithium Cobaltate (LCO), 1.5wt% of conductive carbon black, and 1.3wt% of polyvinylidene fluoride (PVDF). And coating the positive slurry on a positive current collector at one time by coating equipment (double-sided coating), drying, slitting and preparing a sheet to obtain the positive pole piece.
3. Preparation of negative plate
Mixing the negative active material, the negative conductive agent, the negative binder and the thickening agent according to a certain proportion, adding deionized water, stirring and dispersing to prepare negative slurry. In the negative electrode slurry, the solid components comprise 96.9% of graphite, 0.5% of conductive carbon black, 1.3% of sodium carboxymethylcellulose (CMC) and 1.3% of Styrene Butadiene Rubber (SBR), and then the negative electrode slurry is coated on a negative electrode current collector (double-sided coating), and the negative electrode pole piece is prepared by drying, slitting and tabletting.
4. Preparation of the Battery
And (3) preparing the positive plate prepared in the step (2), the negative plate prepared in the step (3) and the diaphragm prepared in the step (1) into a winding core (battery core), wherein the total thickness of the battery core is 5mm, preparing the battery core and the aluminum plastic film into a battery, then performing the working procedures of electrolyte injection, aging, formation, sorting and the like, and finally testing the electrochemical performance of the battery.
Example 2
The process is carried out according to example 1, with the difference from example 1 that:
1. preparation of the separator
(1) Preparing first ceramic layer slurry
Titanium dioxide particles (first ceramic particles, dv 50) 2 1.5 μm) and lithium tantalate (ion conductor particles, dv50 1 3 μm) was mixed with polyvinylpyrrolidone (first binder) to obtain a first adhesive layer slurry. Wherein, based on the total mass of the first ceramic layer slurry, the content of the first ceramic particles is 49wt%, the content of the ion conductor particles is 49wt%, and the content of the first binder is 2wt%;
(2) Preparing the second ceramic layer slurry
Titanium dioxide particles (second ceramic particles, dv 50) 3 1.5 μm) and polyvinylpyrrolidone (second binder) to obtain a second ceramic layer slurry. Wherein the content of the second ceramic particles is 98wt% based on the total mass of the second ceramic layer slurryThe content of the second binder is 2wt%;
wherein the content of the first and second substances,
Figure BDA0003838812250000131
the ratio of (a) to (b = 0.5), the thickness of the first ceramic layer being 5 μm and the thickness of the second ceramic layer being 5 μm.
Example 3
1. Preparation of the separator
(1) Preparing first ceramic layer slurry
Magnesium nitride particles (first ceramic particles, dv 50) 2 1 μm), lithium titanium phosphate (ion conductor particles, dv50 1 2.5 μm) was mixed with a copolymer of styrene-butadiene (first binder) to obtain a first paste for a rubber layer. Wherein, based on the total mass of the first ceramic layer slurry, the content of the first ceramic particles is 49wt%, the content of the ion conductor particles is 49wt%, and the content of the first binder is 2wt%;
(2) Preparing the second ceramic layer slurry
Magnesium nitride particles (second ceramic particles, dv 50) 3 1 μm) and a styrene-butadiene copolymer (second binder) to obtain a second ceramic layer slurry. Wherein, based on the total mass of the second ceramic layer slurry, the content of the second ceramic particles is 98wt%, and the content of the second binder is 2wt%;
(3) Adopting any one coating process of gravure coating, dip coating, transfer coating, spraying and the like, performing double-sided coating on the arc area of the diaphragm base material by using first glue layer slurry, performing double-sided coating on the flat area of the diaphragm base material by using second ceramic layer slurry, and drying;
wherein the content of the first and second substances,
Figure BDA0003838812250000141
the ratio of (a) to (b = 0.4), the thickness of the first ceramic layer being 4 μm and the thickness of the second ceramic layer being 4 μm.
Example 4
The process is carried out according to example 1, with the difference from example 1 that: dv50 2 2.4 μm, dv50 1 Is 3 μm, wherein,
Figure BDA0003838812250000142
=0.8.
Example 5
The process is carried out according to example 1, with the difference from example 1 that: dv50 2 0.3 μm, dv50 1 Is 3 μm, wherein,
Figure BDA0003838812250000143
=0.1.
Example 6
The process is carried out according to example 1, with the difference from example 1 that: the width L of the arc area is 0.01mm, and the inflection point of the bending part of the diaphragm bending area is included.
Example 7
The process is carried out according to example 1, with the difference from example 1 that: the width L of the arc zone is 5mm, and the inflection point of the bending part of the diaphragm bending area is included.
Example 8
The process is carried out according to example 1, with the difference from example 1 that: based on the total mass of the first ceramic layer slurry, the content of the first ceramic particles was 65.4wt%, the content of the ion conductor particles was 32.6wt%, and the content of the first binder was 2wt%.
Example 9
The process is carried out according to example 1, with the difference from example 1 that: based on the total mass of the first ceramic layer slurry, the content of the first ceramic particles was 32.6wt%, the content of the ion conductor particles was 65.4wt%, and the content of the first binder was 2wt%.
Example 10
The process is carried out according to example 1, with the difference from example 1 that: the ion conductor particles are a mixture of lithium phosphate and lithium tantalate (the mass ratio is 1:1).
Comparative example 1
The process is carried out according to example 1, with the difference from example 1 that: the first ceramic layer is free of ionic conductor particles.
Comparative example 2
With reference to example 1, withExample 1 differs in that: dv50 of the first ceramic particle 1 Dv50 of ion conductor particles of 3 μm 1 Is 3 μm, wherein,
Figure BDA0003838812250000161
the ratio of (a) =1.
Comparative example 3
The process is carried out according to example 1, with the difference from example 1 that: dv50 of the first ceramic particle 1 A Dv50 of ion conductor particles of 3 μm 1 Is 1.5 μm, wherein,
Figure BDA0003838812250000162
the ratio of (2).
Examples of the experiments
(1) Normal temperature cycle test
The battery is placed in an environment with the temperature of 25 ℃, the battery is charged to 4.45V by using a 3C constant current and constant voltage, and the battery is charged to a cut-off current of 0.05C by using a 4.45V constant voltage; then standing for 15min; discharge to 3V with 1C current. Recording the initial capacity as Q1, recording the capacity as Q2 after the cycle to 600 weeks, and calculating the capacity retention rate after the normal temperature cycle of the battery by the following formula: capacity retention (%) = (Q2/Q1) 100%.
(2) Battery expansion test
Measuring the initial thickness M1 of the electrode plate, measuring the thickness M2 after the electrode plate is cycled for 600 weeks, and calculating the expansion rate of the battery after normal-temperature cycling according to the following formula: battery swelling rate (%) = [ (M2-M1)/M1 ]100%.
(3) Battery lithium assay
And (4) disassembling the battery which is circulated for 600 weeks to observe whether a lithium precipitation phenomenon occurs.
TABLE 1
Figure BDA0003838812250000171
The results in table 1 show that the problem of black spot lithium deposition in the circular arc area of the diaphragm in the embodiment of the present invention is solved, which indicates that adding the ion conductor particles to the first ceramic layer in the circular arc area can improve the lithium ion transport capability, and increase the particle size of the ion conductor particles, so that the particle size difference between the ion conductor particles and the first ceramic particles is large, thereby forming a structure with more pores between the particles, and under the support of larger particles, the occurrence of black spot lithium deposition in the bending area of the winding core due to the blockage of the diaphragm pores caused by the stress concentration in the circular arc area of the winding core, which obstructs the lithium ion transport, can be avoided.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, which is intended to cover any modifications, equivalents and the like included within the spirit and scope of the present invention.

Claims (10)

1. A diaphragm, comprising a substrate divided into a circular arc region and a flat region; at least one surface of the circular arc area is provided with a first ceramic layer, and at least one surface of the flat area is provided with a second ceramic layer;
wherein the first ceramic layer comprises ion conductor particles and first ceramic particles;
the ion conductor particles have a median diameter Dv50 1 And the median particle diameter Dv50 of the first ceramic particles 2 Satisfies the following conditions:
Figure FDA0003838812240000011
2. a septum as defined in claim 1, wherein the Dv50 is 1 And said Dv50 2 Satisfies the following conditions:
Figure FDA0003838812240000012
3. the membrane of claim 1, wherein the ion conductor particles have a Dv50 of 1 0.1 μm to 10 μm, the Dv50 of the first ceramic particles 2 Is 0.01-8 μm;
preferably, dv50 of the ion conductor particle 1 2 μm to 8 μm, the first ceramic particlesDv50 of the granule 2 Is 0.1 μm to 4 μm.
4. The separator according to claim 1, wherein the mass ratio of the ion conductor particles to the first ceramic particles is (0.1-10): 1.
5. The separator of claim 1, wherein the first ceramic layer has a thickness of 0.5-20 μ ι η;
and/or the thickness of the second ceramic layer is 0.5-20 μm.
6. The separator according to claim 1, wherein the ion conductor particles are lithium-containing inorganic salts;
and/or, the lithium-containing inorganic salt is selected from at least one of lithium phosphate, lithium tantalate, lithium zirconate, lithium titanium phosphate, lithium nitride, lithium lanthanum titanate, lithium aluminum titanium phosphate, and lithium germanium thiophosphate.
7. The separator of claim 1, wherein the second ceramic layer comprises second ceramic particles;
and/or the first ceramic particles and the second ceramic particles are each independently selected from at least one of metal oxides, inorganic metal salts, metal nitrides, and inorganic ceramic solid-state electrolytes.
8. A winding core, characterized in that the winding core is a winding structure formed by a first diaphragm, a first pole piece, a second diaphragm and a second pole piece which are sequentially stacked, wherein the first diaphragm and the second diaphragm are the diaphragms in any one of claims 1 to 7;
wherein, along the stretching direction of the winding core, the width of the arc area is not more than the bending part of the winding structure, and the width of the flat area is not less than the non-bending part of the winding structure.
9. The winding core of claim 8, wherein the arc region has a width L of
Figure FDA0003838812240000021
Figure FDA0003838812240000022
Wherein d is the thickness of the winding core.
10. A battery comprising at least one of the separator of any one of claims 1-7 and the jellyroll of claim 8 or 9.
CN202211096160.1A 2022-09-08 2022-09-08 Diaphragm, roll up core and battery Pending CN115275521A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102015202972A1 (en) * 2015-02-19 2016-08-25 Robert Bosch Gmbh Flexible inorganic-polymer composite separator for a lithium-oxygen cell
CN106711380A (en) * 2017-01-05 2017-05-24 南京航空航天大学 Composite ceramic membrane for lithium ion battery
CN112968254A (en) * 2021-01-29 2021-06-15 东莞维科电池有限公司 Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102015202972A1 (en) * 2015-02-19 2016-08-25 Robert Bosch Gmbh Flexible inorganic-polymer composite separator for a lithium-oxygen cell
CN106711380A (en) * 2017-01-05 2017-05-24 南京航空航天大学 Composite ceramic membrane for lithium ion battery
CN112968254A (en) * 2021-01-29 2021-06-15 东莞维科电池有限公司 Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery

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