CN116344961A - Diaphragm-free battery cell, preparation method thereof and lithium ion battery - Google Patents

Diaphragm-free battery cell, preparation method thereof and lithium ion battery Download PDF

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Publication number
CN116344961A
CN116344961A CN202310580832.4A CN202310580832A CN116344961A CN 116344961 A CN116344961 A CN 116344961A CN 202310580832 A CN202310580832 A CN 202310580832A CN 116344961 A CN116344961 A CN 116344961A
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layer
positive
negative
negative electrode
positive electrode
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Chinese (zh)
Inventor
尚随军
王林
袁丹丹
陈佳杰
胡先刚
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Suzhou Youlionbattery Inc
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Suzhou Youlionbattery Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat 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
    • 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
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • 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 invention provides a diaphragm-free battery cell, a preparation method thereof and a lithium ion battery, and belongs to the technical field of batteries, wherein the diaphragm-free battery cell is formed by laminating or winding a positive plate and a negative plate which are arranged in a laminated manner; the positive plate comprises a positive composite current collector and a positive material arranged on the surface of the positive composite current collector, and the negative plate comprises a negative composite current collector and a negative material arranged on the surface of the negative composite current collector; the positive composite current collector comprises a positive substrate layer and a positive conductive layer arranged on one side of the positive substrate layer, and the negative composite current collector comprises a negative substrate layer and a negative conductive layer arranged on one side of the negative substrate layer. According to the invention, no additional diaphragm is needed, and the safety problems caused by the condition of wrinkling the diaphragm and poor diaphragm alignment are avoided. The battery cell is simple in structure, low in cost, high in yield and safety performance, and the energy density and the multiplying power performance of the battery prepared based on the battery cell are improved effectively.

Description

Diaphragm-free battery cell, preparation method thereof and lithium ion battery
Technical Field
The invention belongs to the technical field of batteries, and particularly relates to a diaphragm-free battery cell, a preparation method thereof and a lithium ion battery.
Background
The lithium battery is of a sandwich structure, namely, is assembled in a wrapping mode of anode/diaphragm/cathode. In actual production, when a conventional metal foil is adopted for coating the anode/cathode, anode/cathode active materials are coated on two sides of a base foil, and two layers of diaphragms are needed to be used for winding, namely, the diaphragms/cathode materials/anode foils/cathode materials/diaphragms/anode materials/anode foils/anode materials, for example, CN210040429U discloses a lithium ion battery cell structure, and the specific technical scheme is as follows: the utility model provides a lithium ion battery electricity core structure, includes positive plate, negative plate, two-layer diaphragm and plastic-aluminum membrane shell, and one of them layer diaphragm is located between positive plate and the negative plate, and another layer diaphragm is located the outside of negative plate, the positive plate is including, the negative plate is outside with two-layer diaphragm coiling together set up and form a roll core structure, roll core structure arranges in the plastic-aluminum membrane shell, be connected through the viscous substance between the negative plate of roll core structure outer lane and the outer lane diaphragm, be connected through hot melt adhesive between outer lane diaphragm and the plastic-aluminum membrane shell. However, the alignment degree of the double-layer slurry and the double-layer diaphragm needs to be considered in the manufacturing process, the process is complex, the energy consumption is high, the yield is low, and potential safety hazards are easily caused when the alignment degree is poor.
In order to increase the energy density of the battery and improve the safety problem caused by the internal short circuit of the battery, a composite foil of a sandwich structure with double conductive layers has been developed, for example, CN115275211a provides a composite current collector comprising a polymer substrate and a first conductive layer disposed on one side surface of the polymer substrate or a first conductive layer and a second conductive layer disposed on opposite side surfaces of the polymer substrate. In the structure, the conductive layers are required to be consistent in material quality, and the conductive layers are required to be coated on the two sides of the substrate layer respectively in the production process, so that the consistency of the thickness of the conductive layers on the two sides is difficult to ensure, the consistency of the active materials coated on the two sides is ensured when the active materials are used for carrying out electron transmission, and the electric performance consistency of the final battery is poor. The same active materials are coated on two sides of the pole piece prepared by the composite foil with the same conductive layer, and only one polarity pole piece can be obtained, and the pole piece with different polarities is prepared again according to the mode. In addition, in order to conduct the active material on the winding core with the anode and the cathode of the battery, the conducting electrode lugs are required to be welded on the conducting layers on two sides of the substrate layer at the same time, and the thickness of the pole piece can be increased when the two layers of the lugs are welded, so that the space utilization rate of the battery is low. In addition, the pole piece prepared by the traditional composite foil needs to use two layers of diaphragms to separate the positive pole piece and the negative pole piece when being wound, so that the cost is increased, and the complexity and the human error of the process are also improved.
Therefore, how to reduce the complexity of the battery structure, reduce the cost and improve the yield and the safety is one of the hot spot directions of the current research.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a diaphragm-free battery cell, a preparation method thereof and a lithium ion battery. According to the invention, no diaphragm is required to be additionally added, so that the cell structure is simplified, the positive electrode substrate layer or the negative electrode substrate layer can be directly utilized as a diaphragm for use, and the safety problems caused by the condition of diaphragm wrinkling and poor diaphragm alignment are avoided; and the composite current collector adopts a mode of arranging the conductive layer on one side, and has simple process, low energy consumption and high yield. The battery cell is simple in structure, low in cost and high in safety performance, and the energy density of the battery prepared based on the battery cell is improved, and the multiplying power performance is effectively improved.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
in a first aspect, the invention provides a diaphragm-free battery cell, wherein the diaphragm-free battery cell is formed by laminating or winding a positive plate and a negative plate which are arranged in a laminated manner;
the positive plate comprises a positive composite current collector and a positive material arranged on the surface of the positive composite current collector, and the negative plate comprises a negative composite current collector and a negative material arranged on the surface of the negative composite current collector;
the positive composite current collector comprises a positive substrate layer and a positive conductive layer arranged on one side of the positive substrate layer, and the negative composite current collector comprises a negative substrate layer and a negative conductive layer arranged on one side of the negative substrate layer.
The invention provides a battery cell without a diaphragm, which does not need to additionally add a diaphragm, simplifies the structure of the battery cell, can directly use an anode substrate layer or a cathode substrate layer as the diaphragm for use, and avoids the safety problems caused by the condition of diaphragm wrinkling and poor diaphragm alignment; and the composite current collector adopts a mode of arranging the conductive layer on one side, and has simple process, low energy consumption and high yield. The battery core has the advantages of simple structure, low cost, short ion migration channel, weak polarization phenomenon, reduced internal resistance and excellent safety performance, multiplying power performance and energy density in the lithium ion battery prepared based on the battery core.
The invention is not limited to the selection of the positive electrode material, and examples thereof include lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, and the like.
The invention is not limited to the choice of the negative electrode material, and examples thereof include graphite, silicon carbon, silicon, lithium titanate, hard carbon, soft carbon, and the like.
The invention only needs to adopt single-sided coating active materials on the composite current collector, and double-sided coating is not needed, so that the consistency of double-sided alignment and double-sided density during coating is not needed to be considered, and the precision is higher.
As a preferable embodiment of the present invention, the positive electrode base layer and the negative electrode base layer are independently polymer layers.
In the present invention, "independently" means that the positive electrode base layer is a high-molecular polymer layer, and the negative electrode base layer is a high-molecular polymer layer, and the selection of the two layers is not interfered with each other.
Preferably, the high molecular polymer layer comprises any one or a combination of at least two of a polyethylene layer, a polypropylene layer, a polyethylene terephthalate layer, a polyimide layer or a polyphenylene sulfide layer.
The thickness of the positive electrode underlayer is preferably 1 to 100 μm, and may be, for example, 1 μm, 5 μm, 10 μm, 25 μm, 50 μm, 75 μm, 100 μm, or the like.
The negative electrode base layer preferably has a thickness of 1 to 100 μm, and may be, for example, 1 μm, 5 μm, 10 μm, 25 μm, 50 μm, 75 μm, 100 μm, or the like.
As a preferable technical solution of the present invention, the positive electrode base layer and the negative electrode base layer are both porous structures.
In the invention, the basal layer is of a porous structure and can be directly used as a diaphragm, and the electrolyte can penetrate through the basal layer through the pores and is transmitted in the vertical direction of the pole piece, so that the electrolyte injection and infiltration efficiency is improved.
The positive electrode base layer preferably has a porosity of 10 to 70%, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, or the like.
Preferably, the porosity of the negative electrode base layer is 10 to 70%, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, or the like.
In the invention, the proper porosity ratio of the substrate layer can ensure the isolation of the anode and the cathode, prevent short circuit, and simultaneously, the Li ions can be rapidly transmitted through the pores.
The pore diameter of the positive electrode underlayer is preferably 0.001 to 1 μm, and may be, for example, 0.001 μm, 0.01 μm, 0.1 μm, 0.5 μm, 1 μm, or the like.
The pore diameter of the negative electrode base layer is preferably 0.001 to 1. Mu.m, and may be, for example, 0.001. Mu.m, 0.01. Mu.m, 0.1. Mu.m, 0.5. Mu.m, 1. Mu.m, or the like.
As a preferred embodiment of the present invention, the positive electrode conductive layer includes any one or a combination of at least two of an aluminum layer, a copper layer, a silver layer, a gold layer, and an iron layer, and is preferably an aluminum layer.
Preferably, the negative electrode conductive layer includes any one or a combination of at least two of a copper layer, an aluminum layer, a silver layer, a gold layer, or an iron layer, preferably a copper layer.
Preferably, the materials of the positive electrode conductive layer and the negative electrode conductive layer are different.
Preferably, the thickness ratio of the positive electrode conductive layer to the negative electrode conductive layer is (0.2-30): (0.1-20), wherein the selection range of the thickness of the positive electrode conductive layer "0.2-30" may be, for example, 0.2, 1, 5, 10, 15, 20, 25 or 30, etc., and the selection range of the thickness of the negative electrode conductive layer "0.1-20" may be, for example, 0.1, 1, 5, 10, 15 or 20, etc.
In the invention, if the thickness ratio of the positive electrode conductive layer to the negative electrode conductive layer is too small, namely the thickness of the positive electrode conductive layer is too small, the conductivity is poor, and the resistivity of the pole piece is increased; if the thickness ratio of the positive electrode conductive layer to the negative electrode conductive layer is too large, that is, the thickness of the positive electrode conductive layer is too large, the positive electrode conductive layer is easy to fall off, and the effect of reducing the cost cannot be achieved.
As a preferable technical scheme of the invention, the positive electrode composite current collector further comprises a positive electrode ceramic layer, wherein the positive electrode ceramic layer is arranged on one surface of the positive electrode substrate layer, which is far away from the positive electrode conductive layer.
The thickness of the positive electrode ceramic layer is preferably 1 to 10 μm, and may be, for example, 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, 10 μm, or the like.
As a preferable technical scheme of the invention, the negative electrode composite current collector further comprises a negative electrode ceramic layer, wherein the negative electrode ceramic layer is arranged on one surface of the negative electrode substrate layer, which is far away from the negative electrode conductive layer.
Preferably, the thickness of the negative electrode ceramic layer is 1 to 10 μm, and may be, for example, 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, 10 μm, or the like.
As a preferable technical scheme of the invention, the diaphragm-free battery cell further comprises a positive electrode lug and a negative electrode lug, wherein the positive electrode lug is arranged on the positive electrode conducting layer, and the negative electrode lug is arranged on the negative electrode conducting layer.
The manner in which the positive electrode tab is disposed on the positive electrode conductive layer is not particularly limited in the present invention, and may be, for example, a welding manner.
The manner in which the negative electrode tab is disposed on the negative electrode conductive layer is not particularly limited in the present invention, and may be exemplified by welding.
In a second aspect, the present invention provides a method for preparing a separator-free cell according to the first aspect, the method comprising the steps of:
(1) Coating the surface of the positive electrode substrate layer with a positive electrode conductive layer to prepare a positive electrode composite current collector,
coating a negative electrode conducting layer on the surface of a negative electrode basal layer to prepare a negative electrode composite current collector;
(2) Coating a positive electrode material on one side coated with a positive electrode conductive layer to prepare a positive electrode plate,
coating a negative electrode material on one side coated with a negative electrode conductive layer to prepare a negative electrode plate;
(3) And laminating or winding the positive electrode plate and the negative electrode plate which are laminated to form the diaphragm-free battery cell.
According to the invention, no diaphragm is required to be additionally added in the process of preparing the battery cell, so that the unreeling/passing/correcting mechanism of the diaphragm is correspondingly reduced, and the cost of the winder is reduced, so that the preparation process saves half of coating time and energy consumption, saves cost and simultaneously reduces the complexity of equipment.
The manner of coating the positive electrode conductive layer and the negative electrode conductive layer in the step (1) is not particularly limited, and a vacuum evaporation method, a magnetron sputtering method, or the like can be used as an example.
As a preferred technical scheme, the preparation method comprises the following steps:
coating an anode conductive layer on the surface of an anode porous substrate layer, coating a ceramic layer on the other surface of the anode porous substrate layer to prepare an anode composite current collector,
coating a negative electrode conductive layer on the surface of a negative electrode porous basal layer, and coating a ceramic layer on the other surface of the negative electrode porous basal layer to prepare a negative electrode composite current collector;
(ii) welding a positive tab to the positive conductive layer and a negative tab to the negative conductive layer;
(III) coating a positive electrode material on one side coated with the positive electrode conductive layer to prepare a positive electrode plate,
coating a negative electrode material on one side coated with a negative electrode conductive layer to prepare a negative electrode plate;
and (IV) laminating or winding the positive electrode plate and the negative electrode plate which are laminated to form the diaphragm-free battery cell.
In a third aspect, the present invention provides a lithium ion battery comprising a separator-free cell according to the first aspect.
Preferably, the lithium ion battery further comprises a housing accommodating the battery cell.
The invention is not limited in material and shape of the shell, and the shell can be made of steel, aluminum plastic film or plastic, etc., the shell can be square, cylindrical, prismatic or triangular, etc., and the shell can be provided with a liquid injection hole, an explosion-proof valve, a positive/negative terminal or an insulating sheet/insulating film, etc.
In the invention, the positive electrode lug and the negative electrode lug are tightly connected with the conducting layer and the shell for conducting current.
The numerical ranges recited herein include not only the recited point values, but also any point values between the recited numerical ranges that are not recited, and are limited to, and for the sake of brevity, the invention is not intended to be exhaustive of the specific point values that the recited range includes.
Compared with the prior art, the invention has the following beneficial effects:
(1) The invention provides a diaphragm-free battery cell, which does not need to additionally add a diaphragm, simplifies the battery cell structure, can directly use an anode substrate layer or a cathode substrate layer as a diaphragm for use, and avoids the safety problems caused by the condition of diaphragm wrinkling and poor diaphragm alignment; and the composite current collector adopts a mode of arranging the conductive layer on one side, and has simple process, low energy consumption and high yield.
(2) The diaphragm-free battery cell provided by the invention has the advantages of simple structure, low cost, shorter ion migration channel, reduced polarization phenomenon, reduced internal resistance and excellent safety performance, rate capability and energy density in the lithium ion battery prepared based on the diaphragm-free battery cell.
Drawings
Fig. 1 is a schematic cross-sectional view of a positive electrode composite current collector and a negative electrode composite current collector in example 1 of the present invention.
Fig. 2 is a schematic cross-sectional view of the positive electrode sheet and the negative electrode sheet in example 1 of the present invention.
Fig. 3 is a schematic cross-sectional view of a positive electrode tab provided with a positive electrode tab in embodiment 1 of the present invention.
Fig. 4 is a schematic diagram of a cell in embodiment 1 of the present invention.
Fig. 5 is a schematic diagram of a cell in embodiment 2 of the present invention.
Fig. 6 is a schematic cross-sectional view of the positive electrode composite current collector of comparative example 1 of the present invention.
Fig. 7 is a schematic cross-sectional view of the positive electrode sheet in comparative example 1 of the present invention.
Fig. 8 is a schematic cross-sectional view of a positive electrode sheet provided with a positive electrode tab in comparative example 1 of the present invention.
Fig. 9 is a schematic diagram of a cell according to comparative example 1 of the present invention.
Fig. 10 is a schematic diagram of the cell of comparative example 2 of the present invention.
Fig. 11 is a flowchart of a process for preparing a lithium ion battery according to the present invention.
Wherein, 1-positive electrode basal layer; 2-a negative electrode base layer; 3-an anode conductive layer; 4-a negative electrode conductive layer; 5-positive electrode material; 6-negative electrode material; 7-positive electrode lugs; 8-separator.
Detailed Description
The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
Example 1
The embodiment provides a diaphragm-free battery cell, as shown in fig. 4, wherein the diaphragm-free battery cell is formed by winding a positive plate and a negative plate which are stacked;
the schematic cross-sectional views of the positive plate and the negative plate are shown in fig. 2, the positive plate comprises a positive composite current collector and a positive material 5 arranged on the surface of the positive composite current collector, the negative plate comprises a negative composite current collector and a negative material 6 arranged on the surface of the negative composite current collector, and the schematic cross-sectional views of the positive composite current collector and the negative composite current collector are shown in fig. 1;
wherein the positive electrode material 5 is lithium iron phosphate, and the negative electrode material 6 is graphite;
the positive composite current collector comprises a positive substrate layer 1 and a positive conductive layer 3 arranged on one side of the positive substrate layer 1, the negative composite current collector comprises a negative substrate layer 2 and a negative conductive layer 4 arranged on one side of the negative substrate layer 2, positive lugs 7 are welded on the positive conductive layer 3, and negative lugs are welded on the negative conductive layer 4, as shown in fig. 3;
wherein the positive electrode substrate layer 1 is a porous polyethylene layer, the negative electrode substrate layer 2 is a porous polyethylene layer, the thicknesses of the positive electrode substrate layer 1 and the negative electrode substrate layer 2 are 12 mu m, the porosities of the positive electrode substrate layer 1 and the negative electrode substrate layer 2 are 40%, and the pore diameters of the positive electrode substrate layer 1 and the negative electrode substrate layer 2 are 0.5 mu m; the positive electrode conductive layer 3 is an aluminum layer, the negative electrode conductive layer 4 is a copper layer, the thickness of the positive electrode conductive layer 3 is 15 mu m, the thickness of the negative electrode conductive layer 4 is 10 mu m, and the thickness ratio is 1.5:1.
The embodiment also provides a preparation method of the diaphragm-free battery cell, which comprises the following steps:
(1) The positive electrode conductive layer 3 is coated on the surface of the positive electrode porous basal layer by adopting a vacuum evaporation method to prepare a positive electrode composite current collector,
coating a negative electrode conductive layer 4 on the surface of a negative electrode porous basal layer by adopting a vacuum evaporation method to prepare a negative electrode composite current collector;
(2) Welding a positive electrode lug 7 on the positive electrode conducting layer 3, and welding a negative electrode lug on the negative electrode conducting layer 4;
(3) Coating a positive electrode material 5 on one side coated with a positive electrode conducting layer 3 to prepare a positive electrode plate,
coating a negative electrode material 6 on one side coated with the negative electrode conductive layer 4 to prepare a negative electrode plate;
(4) And winding and forming the positive plate and the negative plate which are arranged in a laminated way to obtain the diaphragm-free battery cell.
Example 2
The embodiment provides a diaphragm-free battery cell, as shown in fig. 5, wherein the diaphragm-free battery cell is formed by laminating a positive plate and a negative plate which are arranged in a laminated manner;
the positive plate comprises a positive composite current collector and a positive material 5 arranged on the surface of the positive composite current collector, and the negative plate comprises a negative composite current collector and a negative material 6 arranged on the surface of the negative composite current collector;
wherein the positive electrode material 5 is lithium iron phosphate, and the negative electrode material 6 is graphite;
the positive composite current collector comprises a positive substrate layer 1 and a positive conductive layer 3 arranged on one side of the positive substrate layer 1, the negative composite current collector comprises a negative substrate layer 2 and a negative conductive layer 4 arranged on one side of the negative substrate layer 2, a positive lug 7 is welded on the positive conductive layer 3, and a negative lug is welded on the negative conductive layer 4;
wherein the positive electrode base layer 1 is a porous polypropylene layer, the negative electrode base layer 2 is a porous polypropylene layer, the thickness of the positive electrode base layer 1 is 1 mu m, the thickness of the negative electrode base layer 2 is 100 mu m, the porosity of the positive electrode base layer 1 is 10%, the porosity of the negative electrode base layer 2 is 70%, the aperture of the positive electrode base layer 1 is 0.01 mu m, and the aperture of the negative electrode base layer 2 is 1 mu m; the positive electrode conductive layer 3 is an aluminum layer, the negative electrode conductive layer 4 is a copper layer, the thickness of the positive electrode conductive layer 3 is 0.2 mu m, the thickness of the negative electrode conductive layer 4 is 20 mu m, and the thickness ratio is 0.2:20.
The embodiment also provides a preparation method of the diaphragm-free battery cell, which comprises the following steps:
(1) The positive electrode conductive layer 3 is coated on the surface of the positive electrode porous basal layer by adopting a vacuum evaporation method to prepare a positive electrode composite current collector,
coating a negative electrode conductive layer 4 on the surface of a negative electrode porous basal layer by adopting a vacuum evaporation method to prepare a negative electrode composite current collector;
(2) Welding a positive electrode lug 7 on the positive electrode conducting layer 3, and welding a negative electrode lug on the negative electrode conducting layer 4;
(3) Coating a positive electrode material 5 on one side coated with a positive electrode conducting layer 3 to prepare a positive electrode plate,
coating a negative electrode material 6 on one side coated with the negative electrode conductive layer 4 to prepare a negative electrode plate;
(4) And forming the lamination of the positive electrode plate and the negative electrode plate which are arranged in a lamination manner to obtain the diaphragm-free battery cell.
Example 3
The embodiment provides a diaphragm-free battery cell, which is formed by winding a positive plate and a negative plate which are stacked;
the positive plate comprises a positive composite current collector and a positive material 5 arranged on the surface of the positive composite current collector, and the negative plate comprises a negative composite current collector and a negative material 6 arranged on the surface of the negative composite current collector;
wherein the positive electrode material 5 is lithium iron phosphate, and the negative electrode material 6 is graphite;
the positive composite current collector comprises a positive substrate layer 1 and a positive conductive layer 3 arranged on one side of the positive substrate layer 1, the negative composite current collector comprises a negative substrate layer 2 and a negative conductive layer 4 arranged on one side of the negative substrate layer 2, a positive lug 7 is welded on the positive conductive layer 3, and a negative lug is welded on the negative conductive layer 4;
wherein the positive electrode base layer 1 is a porous polyimide layer, the negative electrode base layer 2 is a porous polyimide layer, the thickness of the positive electrode base layer 1 is 100 μm, the thickness of the negative electrode base layer 2 is 1 μm, the porosity of the positive electrode base layer 1 is 70%, the porosity of the negative electrode base layer 2 is 10%, the pore diameter of the positive electrode base layer 1 is 1 μm, and the pore diameter of the negative electrode base layer 2 is 0.01 μm; the positive electrode conductive layer 3 is an aluminum layer, the negative electrode conductive layer 4 is a copper layer, the thickness of the positive electrode conductive layer 3 is 30 mu m, the thickness of the negative electrode conductive layer 4 is 0.1 mu m, and the thickness ratio is 30:0.1.
The embodiment also provides a preparation method of the diaphragm-free battery cell, which comprises the following steps:
(1) The positive electrode conductive layer 3 is coated on the surface of the positive electrode porous basal layer by adopting a vacuum evaporation method to prepare a positive electrode composite current collector,
coating a negative electrode conductive layer 4 on the surface of a negative electrode porous basal layer by adopting a vacuum evaporation method to prepare a negative electrode composite current collector;
(2) Welding a positive electrode lug 7 on the positive electrode conducting layer 3, and welding a negative electrode lug on the negative electrode conducting layer 4;
(3) Coating a positive electrode material 5 on one side coated with a positive electrode conducting layer 3 to prepare a positive electrode plate,
coating a negative electrode material 6 on one side coated with the negative electrode conductive layer 4 to prepare a negative electrode plate;
(4) And winding and forming the positive plate and the negative plate which are arranged in a laminated way to obtain the diaphragm-free battery cell.
Example 4
The difference between this embodiment and embodiment 1 is that this embodiment is provided with a positive electrode ceramic layer having a thickness of 3 μm on the side of the positive electrode base layer 1 away from the positive electrode conductive layer 3, and a negative electrode ceramic layer having a thickness of 3 μm on the side of the negative electrode base layer 2 away from the negative electrode conductive layer 4.
The remaining preparation methods and parameters remain the same as in example 1.
Example 5
The difference between this example and example 4 is that the thickness of the positive electrode ceramic layer is 1 μm and the thickness of the negative electrode ceramic layer is 1 μm.
The remaining preparation methods and parameters remain the same as in example 4.
Example 6
The difference between this example and example 4 is that the thickness of the positive electrode ceramic layer is 10 μm and the thickness of the negative electrode ceramic layer is 10 μm.
The remaining preparation methods and parameters remain the same as in example 4.
Example 7
This example differs from example 1 in that the positive electrode base layer 1 and the negative electrode base layer 2 are non-porous.
The remaining preparation methods and parameters remain the same as in example 1.
Comparative example 1
The comparative example provides a battery cell, as shown in fig. 9, which is formed by winding a separator 8, a negative electrode sheet, a separator 8 and a positive electrode sheet, which are sequentially stacked;
the negative electrode plate comprises a negative electrode material 6, a negative electrode composite current collector and a negative electrode material 6 which are sequentially stacked, wherein the negative electrode composite current collector comprises a negative electrode conductive layer 4 welded with a negative electrode lug, a negative electrode basal layer 2 and a negative electrode conductive layer 4 welded with a negative electrode lug which are sequentially stacked, and the negative electrode conductive layer is a copper layer;
the cross-sectional schematic diagram of the positive plate is shown in fig. 7, and comprises a positive electrode material 5, a positive electrode composite current collector and a positive electrode material 5 which are sequentially stacked, the cross-sectional schematic diagram of the positive electrode composite current collector is shown in fig. 6, the positive electrode composite current collector comprises a positive electrode conductive layer 3 welded with a positive electrode lug 7, a positive electrode substrate layer 1, a positive electrode conductive layer 3 welded with a positive electrode lug 7 and a positive electrode material 5 which are sequentially stacked, and the positive electrode conductive layer is an aluminum layer as shown in fig. 8; the diaphragm 8 is made of polyethylene.
The remaining preparation methods and parameters remain the same as in example 1.
Comparative example 2
The comparative example provides a battery cell, as shown in fig. 10, which is formed by stacking a separator 8, a negative electrode sheet, a separator 8 and a positive electrode sheet in this order;
the negative electrode sheet comprises a negative electrode material 6, a negative electrode conductive layer 4 welded with a negative electrode lug, a negative electrode substrate layer 2, a negative electrode conductive layer 4 welded with a negative electrode lug and the negative electrode material 6 which are sequentially stacked, and the positive electrode sheet comprises a positive electrode material 5, a positive electrode conductive layer 3 welded with a positive electrode lug 7, a positive electrode substrate layer 1, a positive electrode conductive layer 3 welded with a positive electrode lug 7 and a positive electrode material 5 which are sequentially stacked; the diaphragm 8 is made of polyethylene, the negative electrode conductive layer is a copper layer, and the positive electrode conductive layer is an aluminum layer.
The remaining preparation methods and parameters remain the same as in example 2.
The compositions of examples and comparative examples were summarized to give table 1.
TABLE 1
Figure SMS_1
Performance testing
The above-mentioned battery cells provided in examples 1-7 and comparative examples 1-2 were made into lithium ion batteries, and the process flow is shown in fig. 11, and the specific steps include: the battery cells provided in the above examples and comparative examples were mounted in a case, connected to the positive and negative electrode posts of the battery by welded tabs, and electrolyte (1 mol/L LiPF was injected between the case and the battery cells 6 EC/DMC solution of (c), wherein the volume ratio of EC to DMC is 1:1).
And performing electrochemical performance test and high temperature test on the lithium ion battery.
The test conditions were: 2C discharge at 25 ℃; heating at 150deg.C for 2h.
The results of the electrochemical performance test are shown in table 2.
TABLE 2
Figure SMS_2
Analysis:
as can be seen from the table, the invention provides the diaphragm-free battery cell, which has the advantages that the battery cell does not need to be additionally provided with a diaphragm, the battery cell structure is simplified, the positive electrode substrate layer or the negative electrode substrate layer can be directly used as the diaphragm, and the safety problems caused by the condition of diaphragm wrinkling and poor diaphragm alignment are avoided; and the composite current collector adopts a mode of arranging the conductive layer on one side, and has simple process, low energy consumption and high yield. Therefore, the diaphragm-free battery cell prepared by the invention has the advantages of simple structure, low cost, short ion migration channel, weak polarization phenomenon, reduced internal resistance and excellent safety performance, multiplying power performance and energy density.
As is clear from comparison of the data results of examples 1 and examples 4 to 6, the safety performance of the battery can be effectively improved by adding the positive electrode ceramic layer and the negative electrode ceramic layer.
As is clear from comparison of the data results of example 1 and example 7, if the positive electrode base layer and the negative electrode base layer were non-porous, the internal resistance of the battery increased, resulting in a sharp decrease in the rate performance of the battery.
As is evident from comparison of the data results of example 1 and comparative examples 1-2, if two separators were added to the cell, the internal resistance of the battery increased, resulting in a decrease in the rate performance of the battery.
The applicant states that the process of the invention is illustrated by the above examples, but the invention is not limited to, i.e. does not mean that the invention must be carried out in dependence on the above process steps. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of selected raw materials, addition of auxiliary components, selection of specific modes, etc. fall within the scope of the present invention and the scope of disclosure.

Claims (10)

1. The diaphragm-free battery cell is characterized in that the diaphragm-free battery cell is formed by laminating or winding a positive plate and a negative plate which are arranged in a laminated manner;
the positive plate comprises a positive composite current collector and a positive material arranged on one side of the positive composite current collector, and the negative plate comprises a negative composite current collector and a negative material arranged on one side of the negative composite current collector;
the positive composite current collector comprises a positive substrate layer and a positive conductive layer arranged on one side of the positive substrate layer, and the negative composite current collector comprises a negative substrate layer and a negative conductive layer arranged on one side of the negative substrate layer;
the positive electrode substrate layer and the negative electrode substrate layer are independently high molecular polymer layers;
the positive electrode substrate layer and the negative electrode substrate layer are porous structures;
the porosity of the positive electrode substrate layer is 10-70%;
the porosity of the negative electrode substrate layer is 10-70%;
and preparing positive and negative electrode plates of the same battery cell, wherein the thickness ratio of the corresponding positive electrode conductive layer to the corresponding negative electrode conductive layer in the positive and negative electrode plates is (0.2-30) (0.1-20).
2. The cell of claim 1, wherein the cell comprises a plurality of cells,
the high polymer layer comprises any one or a combination of at least two of a polyethylene layer, a polypropylene layer, a polyethylene terephthalate layer, a polyimide layer and a polyphenylene sulfide layer;
the thickness of the positive electrode substrate layer is 1-100 mu m;
the thickness of the negative electrode substrate layer is 1-100 mu m.
3. The separator-free cell of claim 1, wherein the positive electrode base layer has an aperture of 0.001-1 μm;
the aperture of the negative electrode substrate layer is 0.001-1 mu m.
4. The separator-free cell of claim 1, wherein the positive electrode conductive layer comprises any one or a combination of at least two of an aluminum layer, a copper layer, a silver layer, a gold layer, or an iron layer;
the negative electrode conductive layer comprises any one or the combination of at least two of a copper layer, an aluminum layer, a silver layer, a gold layer and an iron layer
The thickness ratio of the positive electrode conductive layer to the negative electrode conductive layer is 1.5:1, 0.2:20 or 30:0.1.
5. The separator-free battery cell of claim 1, wherein the positive electrode composite current collector further comprises a positive electrode ceramic layer, the positive electrode ceramic layer being disposed on a side of the positive electrode substrate layer remote from the positive electrode conductive layer;
the thickness of the positive electrode ceramic layer is 1-10 mu m.
6. The separator-free cell of claim 5, wherein the negative electrode composite current collector further comprises a negative electrode ceramic layer disposed on a side of the negative electrode base layer remote from the negative electrode conductive layer;
the thickness of the negative electrode ceramic layer is 1-10 mu m.
7. The separator-free cell of claim 1, further comprising a positive tab disposed on the positive conductive layer and a negative tab disposed on the negative conductive layer.
8. A method of preparing a separator-free cell according to any one of claims 1 to 7, comprising the steps of:
(1) Coating the surface of the positive electrode substrate layer with a positive electrode conductive layer to prepare a positive electrode composite current collector,
coating a negative electrode conducting layer on the surface of a negative electrode basal layer to prepare a negative electrode composite current collector;
(2) Coating a positive electrode material on one side coated with a positive electrode conductive layer to prepare a positive electrode plate,
coating a negative electrode material on one side coated with a negative electrode conductive layer to prepare a negative electrode plate;
(3) And laminating or winding the positive electrode plate and the negative electrode plate which are laminated to form the diaphragm-free battery cell.
9. The preparation method according to claim 8, characterized in that the preparation method comprises the steps of:
coating an anode conductive layer on the surface of an anode porous substrate layer, coating a ceramic layer on the other surface of the anode porous substrate layer to prepare an anode composite current collector,
coating a negative electrode conductive layer on the surface of a negative electrode porous basal layer, and coating a ceramic layer on the other surface of the negative electrode porous basal layer to prepare a negative electrode composite current collector;
(ii) welding a positive tab to the positive conductive layer and a negative tab to the negative conductive layer;
(III) coating a positive electrode material on one side coated with the positive electrode conductive layer to prepare a positive electrode plate,
coating a negative electrode material on one side coated with a negative electrode conductive layer to prepare a negative electrode plate;
and (IV) laminating or winding the positive electrode plate and the negative electrode plate which are laminated to form the diaphragm-free battery cell.
10. A lithium ion battery comprising a separator-free cell according to any one of claims 1-7.
CN202310580832.4A 2023-05-23 2023-05-23 Diaphragm-free battery cell, preparation method thereof and lithium ion battery Pending CN116344961A (en)

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