CN113270589A - Lithium ion battery, bipolar current collector and manufacturing method thereof - Google Patents

Lithium ion battery, bipolar current collector and manufacturing method thereof Download PDF

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CN113270589A
CN113270589A CN202110574110.9A CN202110574110A CN113270589A CN 113270589 A CN113270589 A CN 113270589A CN 202110574110 A CN202110574110 A CN 202110574110A CN 113270589 A CN113270589 A CN 113270589A
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layer
current collector
bonding
metal
copper
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赵倩
郭敏
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Xiamen Haichen New Energy Technology 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
    • 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
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • 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
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H01M4/662—Alloys
    • 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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Abstract

A lithium ion battery, a bipolar current collector and a manufacturing method thereof belong to the field of lithium ion batteries. The current collector includes a polymer film layer and a negative polarity conductive layer and a positive polarity conductive layer bonded to opposite surfaces thereof, and a first adhesive layer is provided between the polymer film layer and the negative polarity conductive layer. The negative conductive layer is integrated with the polymer film layer by chemical bonding by using the first bonding layer. The current collector has strong anti-stripping capability, and is beneficial to improving the performance of the battery after being used for preparing the battery.

Description

Lithium ion battery, bipolar current collector and manufacturing method thereof
Technical Field
The application relates to the field of lithium ion batteries, in particular to a lithium ion battery, a bipolar current collector and a manufacturing method of the bipolar current collector.
Background
As one of the indispensable components of lithium ion batteries, the current collectors widely used in cell production at present mainly include positive metal aluminum foil current collectors and negative metal copper foil current collectors. These metal foils have the advantage of high conductivity, but the metal foils are susceptible to breakage during production and processing, resulting in loss. In addition, the thickness of the positive aluminum foil current collector applied to the production of the battery core is 10-20 microns, and the thickness of the negative copper foil is 6-8 microns, so that the energy density of the battery is not favorably improved.
Therefore, ultra-pure, high conductivity, high strength, high flexibility and ultra-thin current collectors are the development trend of future current collectors.
The ultra-thin current collector is a main research direction, for example, a process of integrating a positive current collector and a negative current collector. Illustratively, a copper layer and an aluminum layer are plated on both side surfaces of the polymer base film, respectively. This may form an integrated bipolar composite current collector. However, such composite current collectors are susceptible to delamination or peeling during manufacture and/or use.
In view of this, the present application is specifically made.
Disclosure of Invention
A current bipolar composite current collector has a structure of a copper plating layer, a base film, and an aluminum plating layer. Due to the difference of the properties of the plating layers on the two sides of the bipolar current collector, different preparation processes are adopted, an aluminum layer is prepared by a chemical vapor deposition method, and a copper layer is prepared by an electroplating method. However, in the operation of plating copper by electroplating, the aluminum layer is corroded by the plating solution. Therefore, in some cases, the copper layer is electroplated and then the aluminum layer is electroplated, so as to avoid the corrosion of the aluminum layer by the electroplating solution.
Although the problem of corrosion of the aluminum layer can be avoided by aluminizing after copper plating, other problems can arise. For example, the temperature of the evaporation heat source in the chemical vapor deposition process used for aluminum plating is high, which results in the deposition film surface temperature approaching 200-300 ℃. Since the thermal characteristics of the copper layer and the base film are different, the thermal stress between the copper layer and the base film is significantly different due to the high-temperature film surface, and thus the copper layer and the base film are easily peeled off.
In view of the above problems, the present application provides a lithium ion battery, a bipolar current collector and a manufacturing method thereof, which can improve or even solve the above problems of easy delamination in the bipolar current collector. Meanwhile, the novel bipolar current collector can keep the flexibility thereof, thereby facilitating further production and processing.
The application is realized as follows:
in a first aspect, the present examples propose a bipolar current collector comprising a polymer membrane layer and a negative polarity conductive layer and a positive polarity conductive layer respectively bonded to both surfaces thereof. The current collector further comprises a first bonding layer, and the negative polarity conducting layer is combined with the polymer film layer into a whole in a chemical bonding mode through the first bonding layer.
Since the first adhesive layer and the polymer film layer are firmly bonded by chemical bonds, peeling between the negative conductive layer and the polymer film layer due to high temperature during fabrication of the positive conductive layer is also alleviated.
The negative polarity conducting layer is combined with the polymer film layer into a whole in a chemical bonding mode through the first bonding layer, so that the combination firmness degree of the negative polarity conducting layer and the polymer film layer can be remarkably improved. Compare in the physical bonding effect of the mechanical interlocking who transfers negative polarity conducting layer particulate matter to the surface of polymer film layer, the scheme of this application can improve the bonding effect, can avoid forming the in-process of positive polarity conducting layer, and the negative polarity conducting layer takes place to peel off.
According to some examples of the present application, the first adhesion layer is any one or combination of Ni, Ti, W, Cr, Cu, and alloys thereof.
According to some examples of the present application, the bipolar current collector includes a bond enhancing layer between the first adhesion layer and the negative polarity conductive layer.
Optionally, the bonding reinforcement layer comprises a process layer stacked from the first adhesive layer; alternatively, the bonding reinforcement layer includes a process layer and a transition layer sequentially stacked from the first adhesive layer. Wherein one or both of the process layer and the transition layer is a copper layer.
The combination enhancement layer can improve the combination firmness degree between the negative polarity conducting layer and the polymer film layer.
According to some examples of the present application, the bipolar current collector includes a first oxidation resistant layer bonded to a surface of the negative polarity conductive layer facing away from the polymer membrane layer. Optionally, the oxidation resistant layer comprises a layer of organic material and/or a layer of inert metal material. Wherein the organic material comprises benzotriazole and any one of the derivatives thereof, and the derivative comprises 5-carboxyl benzotriazole or benzotriazole-5-octyl carboxylate; wherein, the inert metal comprises any one simple substance of Sn, Cr, Zn and Ni.
The first oxidation resistant layer can realize the oxidation resistance effect on the negative polarity conducting layer, so that the problems of conductivity reduction and the like of the negative polarity conducting layer are avoided.
According to some examples of the present application, the negative conductive layer is formed on the polymer film layer by magnetron sputtering.
According to some examples of the present application, the bipolar current collector includes a second oxidation resistant layer bonded to a surface of the positive polarity conductive layer facing away from the polymer film layer.
The second oxidation resistant layer can prevent or mitigate oxidation of the positive conductive layer, thereby maintaining its electrical properties, such as conductivity.
According to some examples of the present application, the positive polarity conductive layer is bonded to the surface of the polymer film layer by a second adhesive layer. The second adhesive layer includes an aluminum-containing compound or a silicon-containing compound.
Wherein the aluminum-containing compound is AlOxAnd the value of x is a real number which is more than or equal to 1.0 and less than or equal to 1.5. Wherein the silicon-containing compound is SiC or Si3N4Or SiOyAnd the value of y is a real number between 1.5 and 2.
According to some examples of the present application, the positive polarity conductive layer is a layered stack of one or more repeating units including a positive polarity metal layer, a positive polarity metal oxide layer and a positive polarity metal layer, which are sequentially stacked, the positive polarity metal oxide layer being AlOxAnd the value of x is a real number which is more than or equal to 1.0 and less than or equal to 1.5.
In a second aspect, the present examples propose a bipolar current collector comprising:
a polymer base layer;
a negative polarity layer formed on one surface of the polymer base layer; the negative polarity layer is provided with a first bonding layer, an optional process layer, an optional transition layer, a first metal layer and a first oxidation resisting layer which are sequentially distributed from one surface in a laminated manner, wherein the first bonding layer is chemically bonded with the polymer base layer;
and a positive polarity layer formed on the other surface of the polymer base layer opposite to the one surface, wherein the positive polarity layer comprises a second adhesive layer, a second metal layer and a second antioxidation layer which are sequentially distributed in a laminated manner from the other surface.
In a third aspect, the present examples provide a method of fabricating a bipolar current collector having a bipolar multilayer structure with improved interlayer peel strength. The manufacturing method comprises the following steps:
providing a polymer-based film;
manufacturing a first bonding layer on one surface of the polymer base film, and manufacturing a copper metal layer on the first bonding layer so that the copper metal layer is indirectly combined with the polymer base film in a chemical bonding mode;
manufacturing an aluminum metal layer on the other surface of the polymer-based film opposite to the one surface;
wherein the chemical bonding is achieved by bonding a material of copper metal or a material of aluminum metal to the surface of the polymer-based film by evaporation coating, magnetron sputtering, water electroplating or electroless plating.
According to some examples of the application, the method of making includes:
manufacturing a metal layer or an alloy layer on the front surface of the polymer base film in a magnetron sputtering mode to form a first bonding layer, wherein the metal layer is one or more of Ni, Ti, W, Cr and Cu, and the alloy layer is one or more of nickel alloy, titanium alloy, tungsten alloy, chromium alloy and copper alloy;
on the first bonding layer, a process layer is made of copper through electro-plating;
on the process layer, a transition layer is made of copper through magnetron sputtering;
on the transition layer, a copper metal layer is made by electroplating with copper;
manufacturing a protective layer on the copper metal layer, wherein the protective layer is made of an organic material or an inert metal; wherein the organic material comprises benzotriazole and any one of the derivatives thereof, and the derivative comprises 5-carboxyl benzotriazole or benzotriazole-5-octyl carboxylate; wherein, the inert metal comprises any one simple substance or combination of a plurality of simple substances in Sn, Cr, Zn or Ni;
on the back of the polymer-based film, an aluminum oxide layer or a silicon compound layer is manufactured in a physical vapor deposition or chemical vapor deposition mode to form a second bonding layer, wherein the aluminum oxide layer is AlOx, the value of x is a real number which is more than or equal to 1.0 and less than or equal to 1.5, the value of the silicon compound layer is SiC, Si3N4 or SiOy, and the value of y is a real number which is more than or equal to 1.5 and less than or equal to 2;
one or more combined layers are manufactured on the second bonding layer to form an aluminum metal layer, and the method for manufacturing the combined layers comprises the steps of manufacturing the aluminum metal layer in an evaporation plating mode, carrying out plasma oxidation on the aluminum metal layer to form a surface oxidation layer, and then manufacturing the aluminum metal layer on the surface of the surface oxidation layer through evaporation plating;
an aluminum oxide layer is manufactured on the aluminum metal layer in an evaporation plating mode, the aluminum oxide layer is made of AlOx, and the value of x is a real number between 1.0 and 1.5.
In a fourth aspect, the present application example proposes a lithium ion battery based on the aforementioned current collector. Which comprises a separator and the aforementioned current collector stacked, and an electrode active material is attached to the surface of the current collector.
In the implementation process, the polymer film and the negative conductive layer are chemically bonded to form an integrated current collector, so that each layer of the integrated bipolar current collector is firmly combined, and the structural stability of the integrated bipolar current collector is improved. In addition, the surface of the conductive layer is subjected to anti-oxidation layer treatment, so that the conductive layer is not easily oxidized.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
Fig. 1 is a schematic structural view of a bipolar current collector in an example of the present application;
fig. 2 shows a schematic structure of a laminated bare cell fabricated based on the current collector of fig. 1;
fig. 3 shows a schematic structural diagram of a wound bare cell fabricated based on a separator and the current collector of fig. 1.
Icon: 200-bipolar composite current collector; 300-lamination bare cell; 301-a membrane; 302-pole piece; and 100-winding the bare cell.
Detailed Description
The current composite current collector, especially the bipolar composite current collector, mostly adopts a stack structure of '1 +1+ 1'. Namely, a polymer basal membrane is used as a base material, and metal nano layers are respectively manufactured on two surfaces of the base material in a spraying or depositing mode, so that a composite positive/negative electrode current collector is obtained.
The positive electrode composite current collector adopts the scheme that: metal layers made of simple aluminum are formed on two surfaces of the base film. The negative electrode composite current collector adopts the scheme that: metal layers made of copper simple substance are formed on two surfaces of the base film. The scheme adopted by the bipolar composite current collector is as follows: a metal layer composed of a copper simple substance and a metal layer composed of an aluminum simple substance are respectively formed on two surfaces of the base film.
These composite current collectors can combine the flexibility of polymeric materials with the conductivity of metals, and can be made relatively thinner. For example, on a micron scale less than a metal foil current collector-aluminum foil 10 to 20 microns, copper foil 6 to 8 microns. In the composite current collector, the thickness of the metal layer bonded to the surface of the base film may be up to a nanometer scale, such as within 10 nanometers, within 20 nanometers, within 50 nanometers, and the like.
However, these composite current collectors described above have some problems in structural stability. For example, the bipolar composite current collector is prone to delamination or peeling during the manufacturing or use process.
In view of this situation, a solution capable of improving the stability of the interlayer structure in the composite current collector is proposed in the present application. That is, the metal layer, particularly the copper layer, is chemically bonded to the base film via the adhesive layer, so that the metal layer and the base film are bonded to each other more firmly and less easily to be separated from each other. Compare in the physical bonding effect that relies on metal particle at the mechanical interlocking of the coarse surface of polymer base layer alone, the scheme of this application can improve the degree of difficulty that the metal level peeled off from the base film.
For example, in the scheme of preparing the bipolar current collector by electroplating copper first and then plating aluminum by chemical vapor deposition, the film surface of the base film generates high temperature due to chemical vapor deposition, so that the copper layer electroplated first is easily separated from the base film. In this regard, in the present application, an adhesive layer is formed between the copper plating layer and the base film. The bonding layer is firmly bonded with the base film, and the copper layer formed on the basis of the bonding layer can be stably and firmly bonded with the base film through the bonding layer and can resist the high-temperature influence in the chemical vapor deposition of aluminum.
The base film in the bipolar composite current collector may be an organic polymer. Illustratively, the material of the base film is one or more of BOPP (Biaxially oriented polypropylene), PET (Polyethylene terephthalate), PI (Polyimide), PS (Polystyrene), PPS (Polyphenylene sulfide), CPP (Cast polypropylene), PEN (Polyethylene naphthalate) for acrylic acid ester), PVC (Polyvinyl chloride), PEEK (polyether ether ketone, Poly (ether-ether-ketone), PES (polyether sulfone resin), PPSM (Polyphenylene sulfone resin), PE (Polyethylene sulfide resins), and nonwoven fabric.
In addition, in the bipolar composite current collector, the number of the base films may be selected to be a single layer or multiple layers. As an example, the multi-layered base film is, for example, two, three, four or more layers. In some examples, the base film is three-layered and of a PP + PET + PP structure distributed in sequence.
The metal layer is, for example, a copper layer or an aluminum layer.
In order to facilitate the manufacturing of the bipolar composite current collector by those skilled in the art, the manufacturing method is proposed as follows: providing a base film of a polymer material; and respectively manufacturing a copper metal layer and an aluminum metal layer on two opposite surfaces of the polymer-based film in a chemical bonding mode. As an example, among others, chemical bonding is achieved by performing evaporation plating, magnetron sputtering, water electroplating, or electroless plating. At least an adhesive layer is formed between the copper metal layer and the polymer base film. Similarly, an adhesive layer may be formed between the aluminum metal layer and the polymer-based film.
The example solution of the present application is able to improve the bonding firmness between layers based on the consideration that: the copper metal material is transferred and attached to the surface of the polymer base film in the above way, and chemical bonds are formed under the action of an energy body such as plasma by utilizing the polarity of the base film and free bonds on the surface of the copper metal layer.
Specifically, in the integrated bipolar composite current collector, the surface of the base film has a structure such as-CH2，-NH2And polar groups such as-OH, -COOH, etc. The electrons at the outermost layer of the metal atoms can be excited by a certain energy source to obtain free electrons, and the free electrons are chemically bonded with the polar groups of the basement membrane.
As an alternative example, the bipolar composite current collector has an aluminum metal layer, an adhesive layer, a base film, an adhesive layer, and a copper metal layer sequentially arranged. The aluminum metal layer is relatively more easily chemically bonded to the base film, and the copper metal layer is relatively more difficult to chemically bond to the base film. Therefore, in practical fabrication, a process method with lower energy relative to the energy for fabricating the copper metal layer can be selected for the aluminum metal layer. The reason for this phenomenon is: the electron orbit of the outermost layer of aluminum atom is unstable, so that the aluminum has strong chemical activity and is easy to oxidize. Therefore, aluminum easily reacts with the base film of the polymer material to form a chemical bond, so that the adhesion between the aluminum layer and the insulating layer is strong. Compared with aluminum atoms, the outermost layer of copper atoms has stable electron orbits, so that the chemical activity of copper is lower than that of aluminum, and stronger energy is needed for excitation, and then a chemical bond is formed with a polar group on the surface of the base film, so that chemical bonding is realized.
In some examples, a bonding enhancement layer may be further configured for the bipolar composite current collector, wherein the bonding enhancement layer is located between the bonding layer on the surface of the polymer film layer and the copper metal layer serving as the negative conductive layer, and the bonding enhancement layer is in contact with the bonding layer and the negative conductive layer, respectively. For the sake of distinction, the aforementioned adhesive layer between the surface of the polymer film layer and the negative-polarity conductive layer is referred to as a first adhesive layer, and the adhesive layer between the surface of the polymer film layer and the aluminum metal layer as the positive-polarity conductive layer is referred to as a second adhesive layer.
As an alternative implementation, the aforementioned bonding reinforcement layer may be a process layer stacked from the surface of the first adhesive layer. Or, as a further alternative implementation, the bonding reinforcement layer may be a process layer and a transition layer stacked in this order from the surface of the first adhesive layer.
In the foregoing scheme, the first adhesion layer may be a simple substance metal such as Ni, Ti, W, Cr, Cu, or the like; or the first bonding layer may be an alloy of one or more of them, such as a copper-nickel alloy, a copper-titanium alloy, a nickel alloy, a titanium alloy, a tungsten alloy, a chromium alloy, a copper alloy, and the like. The thickness of the first adhesive layer may be in the nanometer scale, for example, 10 nm. The first adhesive layer can be made by magnetron sputtering on the surface of the polymer film layer, i.e. the base film.
The process layer and the transition layer are copper metal material layers matched with the negative polarity conducting layer. Thus, in some examples, the process layer and the transition layer may each be selected to be copper layers. And for example, a copper material can be used to form a process layer with a thickness of 20nm on the surface of the first adhesive layer by evaporation plating. And then, a transition layer with the thickness of 20nm is manufactured on the process layer by adopting a copper material in a magnetron sputtering mode.
On the basis of the above-mentioned combination enhancement layer, a copper metal material can also be selectively fabricated on the transition layer (with a thickness of 1 μm, for example) by means of water electroplating.
In addition to improving the bonding strength of the layer, a first oxidation resistant layer may be formed on the negative conductive layer (e.g., copper metal layer) in some examples, in case of oxidation of the negative conductive layer.
The first oxidation resistant layer may be selected, for example, to be a layer of inert metal material. Illustratively, the inert metal includes any one of the simple substances of Sn, Cr, Zn, and Ni. The inert metal protects the negative conductive layer from direct contact with oxidizing substances, so that oxidation of the negative conductive layer can be avoided or reduced.
In addition, the first oxidation resistant layer may also be selected to be a non-metal protective layer. For example, an organic material, illustratively, the first oxidation resistant layer may be benzotriazole and its derivatives; these organic materials can be made into a layered structure by means of water plating and formed on the negative polarity conductive layer. Including but not limited to 5-carboxybenzotriazole, octyl benzotriazole-5-carboxylate, and the like. Benzotriazole and its derivatives can form covalent bonds and coordination bonds with copper atoms in the copper metal layer as the negative-polarity conductive layer, and can also form chain polymers. Thus, the organic material can form a multilayer protective film on the surface of copper, so that the surface of copper does not have redox reaction, thereby achieving the effects of corrosion prevention and oxidation prevention.
The scheme performs adhesion enhancement and oxidation resistance optimization on the negative polarity conducting layer, and in other examples, adhesion and oxidation resistance optimization can also be performed on the positive polarity conducting layer.
For example, the aluminum metal layer and the base film are reinforced with a second adhesive layer as previously described, wherein the second adhesive layer may have a different suitable material selection. For example, the second adhesion layer is an aluminum-containing compound or alternatively a silicon-containing compound. Wherein the compound containing aluminium is, for example, AlOx(aluminum oxide), wherein the value of x is a real number which is more than or equal to 1.0 and less than or equal to 1.5. For the example of aluminum oxide, it may be deposited on the surface of the polymer film layer (away from the negative polarity) by, for example, chemical vapor deposition or physical vapor depositionConductive layer side) as a second adhesive layer, an aluminum oxide layer as thick as 5nm is deposited. Alternatively, a silicon-containing compound may be used for the second adhesive layer. For example, silicon carbide (SiC), silicon nitride (Si)3N4) Or silicon oxide (SiO)y). Wherein the value of y in the silicon oxide can be a real number between 1.5 and 2.
The positive conductive layer in the bipolar composite current collector can be manufactured on the second bonding layer in an evaporation plating mode; for example, an aluminum metal material is deposited by evaporation to form an aluminum metal layer. In other examples, the positive conductive layer may be configured as a combination of sub-layers, in addition to the aluminum metal layer. For example, the positive polarity conductive layer may include an aluminum metal layer, a reinforcement layer, and an aluminum metal layer, which are sequentially distributed. In an example where the positive polarity conductive layer is a composite structure of a plurality of sublayers, the preparation method thereof may be, for example:
and manufacturing a first aluminum metal layer on the second adhesive layer by means of evaporation plating. Then, the surface of the aluminizer is cleaned and oxidized by ionizing argon and oxygen through plasma equipment on the first aluminum metal layer to generate a compact layer of AlOx(i.e. a reinforcement layer, for example 5nm thick). Then, a second aluminum metal layer is formed on the reinforcing layer by evaporation plating. In some examples, the positive conductive layer has a three-layer structure of the aluminum metal layer, the reinforcement layer, and the aluminum metal layer. In other examples, the positive conductive layer may be formed by stacking a plurality of (the specific number may be selected according to design requirements) the three-layer structures. In some examples, the thickness for a positive polarity conductive layer consisting of a stack of multiple of the foregoing three-layer structures is 200 nm.
In addition to the positive conductive layer being bonded to the polymer film layer by the second adhesive layer to enhance the bonding strength, the positive conductive layer may be optionally protected against oxidation in a manner similar to the oxidation-resistant operation described above for the negative conductive layer. For example, an aluminum oxide layer (with a thickness of, for example, 20nm) is formed on top of the positive conductive layer by evaporation.
The above scheme illustrates a bipolar composite current collector with enhanced layer junction peel strength in the present application. Based on similar principles, in other application examples of the present application, a unipolar composite current collector-a negative composite current collector/also a positive composite current collector-is proposed.
For example, the negative composite current collector includes a polymer film layer and a negative conductive layer. And the negative polarity conducting layer and the polymer film layer are combined into a whole in a chemical bonding mode through the adhesive layer. The negative conductive layer can be bonded to one surface of the polymer film layer or bonded to both surfaces of the polymer film layer. The negative conductive layer can be selected to be a copper material, for example.
Alternatively, the positive composite current collector includes a polymer film layer and a positive conductive layer. And the positive conductive layer and the polymer film layer are combined into a whole in a chemical bonding mode through the adhesive layer. The positive conductive layer can be bonded to one surface of the polymer film layer or bonded to both surfaces of the polymer film layer. The positive conductive layer can be selected, for example, as an aluminum material.
The bipolar current collector in the present example will be described in detail below with reference to the accompanying drawings. As shown in fig. 1, a multi-layered bipolar composite current collector 200 is disclosed.
The bipolar composite current collector 200 has a base layer B;
in the orientation shown in fig. 1, on the upper side of the base layer B: an adhesive layer a1 (second adhesive layer); functional layer a2 (positive polarity conductive layer); protective layer a3 (second antioxidation layer);
in the orientation shown in fig. 1, on the underside of the substrate B: an adhesive layer C1 (first adhesive layer); a process layer C2; a transition layer C3; functional layer C4 (negative polarity conductive layer); protective layer C5 (first oxidation resistant layer). Wherein the process layer C2 and the transition layer C3 constitute a bonding enhancing layer.
Unlike the bipolar composite current collector of the structure of "1 +1+ 1" mentioned above, the bipolar composite current collector 200 in the present example is an "N +1+ N" multilayer structure design. Wherein, structural stability between basic unit and the functional layer can be guaranteed through the tie coat of addding for difficult separation between each layer. Moreover, the added protective layer can realize the anti-oxidation protection of the functional layer.
The current collector may be manufactured by the following method.
On the front side of the polymer-based film, a metal layer or an alloy layer is produced as a first adhesive layer by means such as magnetron sputtering. On top of the first adhesive layer, a first copper metal layer is made by means of electro-plating as a process layer. And (4) manufacturing a transition layer on the process layer by using copper magnetron sputtering. On top of the transition layer, a copper metal layer is made by electro-plating using copper. And manufacturing a first protective layer on the copper metal layer.
On the back of the polymer base film, an aluminum oxide layer or a silicon compound layer is manufactured in a physical vapor deposition or chemical vapor deposition mode to serve as a second bonding layer; one or more combined layers are formed on the second adhesive layer to form an aluminum metal layer. The method for manufacturing the combination layer comprises the steps of manufacturing an aluminum metal layer in an evaporation plating mode, carrying out plasma oxidation on the aluminum metal layer to form a surface oxidation layer, and then manufacturing the aluminum metal layer on the surface of the surface oxidation layer through evaporation plating; and forming an aluminum oxide layer on the one or more combined layers by evaporation plating to serve as a second protective layer.
In order to verify the interlayer bonding firmness of the bipolar composite current collector in the example of the present application, a plurality of bipolar composite current collectors obtained by the above-described manufacturing method were tested. The test adopts a single variable, tests are carried out on the high molecular materials of different polymer film layers and different materials and thicknesses of the first bonding layer, and the bonding performance is represented by using the peel strength; the specific method comprises the following steps: the sample was prepared as a strip sample, the adhesive layer and the base layer were peeled off using a tensile machine, and the peel force at which peeling occurred was recorded.
Figure BDA0003083712590000131
Figure BDA0003083712590000141
Note: in the table, "/" indicates no adhesive layer.
In the table, the peel strength of the copper metal current collector layer means: the peeling force with which the adhesive layer and the functional layer are peeled off integrally from the base layer.
From the above table the following conclusions can be drawn:
comparing the group 1 and the group 2, wherein for different base films, it is known that PET (polyethylene terephthalate) as the base film, the peel strength of the resulting copper metal layer is enhanced compared to PP (polypropylene) base film, because the PET side chain has more polar groups and thus is able to form more chemical bonds.
Comparing the group 3 and the group 5, wherein for different first bonding layer materials, Cu/Ni alloy is used as the bonding layer material, compared with Cu metal, the obtained copper metal layer has enhanced peel strength. In further research, it is found that when the doping content of Ni in the Cu/Ni alloy is 5 wt% to 30 wt% (especially 30 wt%), the Cu/Ni alloy has chemical activity of Ni, so that the Cu/Ni alloy is easier to deposit on the substrate during magnetron sputtering process than the Cu alloy and is easier to react with the substrate polymer to produce chemical bonds.
Comparative groups 1, 3 and 4, where the peel strength increased with increasing thickness of the adhesive layer for different first adhesive layer thicknesses.
In comparison with groups 1 to 6, the peel strength for each case containing the first adhesive layer is significantly better than that of the case without the first adhesive layer.
Based on the bipolar composite current collector 200, the bipolar composite current collector can be applied to manufacturing products such as pole pieces, battery cores, lithium ion batteries and the like.
The pole piece comprises a bipolar composite current collector 200 and an electrode active material (a positive electrode active material such as lithium iron phosphate and a negative electrode active material such as graphite) attached to the surface of the current collector. When the composite current collector in the pole piece is unipolar, the active material corresponding thereto is disposed accordingly.
Further, the battery core comprises a diaphragm and a pole piece which are stacked. As shown in fig. 2, the bare cell 300 is laminated. It comprises 6 bipolar composite current collectors 200, and 7 separators 301, and the bipolar composite current collectors and separators are stacked alternately. The bipolar composite current collector 200 to which the electrode active material is attached is represented by a three-layer structured pole piece 302.
Because in the naked electric core of above-mentioned lamination, adopted the bipolar composite current collector of integrated structure, consequently need not consider at alignment and dislocation scheduling problem when carrying out the lamination of independent positive pole piece and independent negative pole piece to can improve preparation efficiency and yield, and then help reducing the cost of manufacture. In addition, since the thickness of the integrated current collector is relatively reduced (compared to a foil current collector, or a separate positive electrode sheet, a separate negative electrode sheet), the energy density (volumetric energy density and mass energy density) can be improved.
The naked electric core of above-mentioned naked electric core of lamination can be through the naked electric core of mode preparation winding structure of coiling. In such an example, more than two diaphragms and more than two pole pieces need to be laminated. Therefore, in order to further reduce the problem of misalignment during stacking, in other examples, a pole piece and a separator may be stacked to form a double-layer structure, and then wound to form a wound bare cell 100 in a wound structure, which is shown in fig. 3.
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are clearly and completely described in the above description with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the above detailed description of the embodiments of the present application, as presented in the figures, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. 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 application.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present application, it should be noted that the terms "upper", "lower", and the like refer to orientations or positional relationships based on orientations or positional relationships shown in the drawings or orientations or positional relationships that the products of the application usually place when using, are only used for convenience of description and simplification of description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.
In the description of the present application, it is further noted that, unless expressly stated or limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.
In the present application, all the embodiments, implementations, and features of the present application may be combined with each other without contradiction or conflict. In the present application, conventional equipment, devices, components, etc. are either commercially available or self-made in accordance with the present disclosure. In this application, some conventional operations and devices, apparatuses, components are omitted or only briefly described in order to highlight the importance of the present application.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (10)

1. The bipolar current collector is characterized by further comprising a first bonding layer, wherein the negative conductive layer is combined with the polymer film layer into a whole in a chemical bonding mode through the first bonding layer.
2. The bipolar current collector of claim 1, wherein the first adhesion layer comprises any one or combination of Ni, Ti, W, Cr, Cu, and alloys thereof.
3. The bipolar current collector of claim 1, wherein the bipolar current collector comprises a bond enhancing layer between the first adhesion layer and the negative conductive layer;
the bonding reinforcement layer includes a process layer stacked from a surface of the first adhesive layer; or, the bonding reinforcement layer comprises a process layer and a transition layer which are sequentially overlapped from the surface of the first bonding layer;
optionally, one or both of the process layer and the transition layer is a copper layer.
4. The bipolar current collector of any one of claims 1 to 3, wherein the bipolar current collector comprises a first oxidation resistant layer bonded to a surface of the negative polarity conductive layer facing away from the polymer film layer;
optionally, the oxidation resistant layer includes an organic material layer and/or an inert metal material layer, wherein the organic material includes any one of benzotriazole and derivatives thereof, and the derivatives include 5-carboxyl benzotriazole or octyl benzotriazole-5-carboxylate; wherein the inert metal comprises any one simple substance of Sn, Cr, Zn and Ni;
optionally, the negative conductive layer is fabricated on the polymer film layer by magnetron sputtering.
5. The bipolar current collector of claim 1, wherein the bipolar current collector comprises a second oxidation resistant layer bonded to a surface of the positive polarity conductive layer facing away from the polymer film layer;
and/or the positive polarity conducting layer is combined on the surface of the polymer film layer through a second bonding layer;
optionally, the second adhesion layer comprises an aluminum-containing compound or a silicon-containing compound; wherein the aluminum-containing compound is AlOxWherein x is a real number between 1.0 and 1.5, and the silicon-containing compound is SiC or Si3N4Or SiOyAnd the value of y is a real number between 1.5 and 2.
6. The bipolar current collector of claim 5, wherein the positive polarity conductive layer comprises a layered stack of one or more repeating units comprising a positive polarity metal layer, a positive polarity metal oxide layer, and a positive polarity metal layer stacked in sequence;
optionally, the positive polarity metal oxide layer is AlOxAnd the value of x is a real number which is more than or equal to 1.0 and less than or equal to 1.5.
7. A bipolar current collector, comprising:
a polymer base layer;
a negative polarity layer formed on one surface of the polymer base layer; the negative polarity layer is provided with a first bonding layer, an optional process layer, an optional transition layer, a first metal layer and a first oxidation resisting layer which are sequentially distributed from one surface in a laminated mode, wherein the first bonding layer is chemically bonded with the polymer base layer;
and a positive polarity layer formed on the other surface of the polymer base layer opposite to the one surface, the positive polarity layer having a second adhesive layer, a second metal layer, and a second antioxidation layer, which are sequentially stacked and distributed from the other surface.
8. A method of fabricating a bipolar current collector having a multi-layer structure and improved interlayer peel strength, the method comprising:
providing a polymer-based film;
manufacturing a first bonding layer on one surface of the polymer base film, and manufacturing a copper metal layer on the first bonding layer so as to indirectly combine the copper metal layer with the polymer base film in a chemical bonding mode;
manufacturing an aluminum metal layer on the other surface of the polymer-based film opposite to the one surface;
wherein the chemical bonding is achieved by performing evaporation coating, magnetron sputtering, water electroplating or chemical plating of the material of the copper metal or the material of the aluminum metal to the surface of the polymer-based film.
9. The method for manufacturing a bipolar current collector according to claim 8, wherein the method for manufacturing comprises:
manufacturing a metal layer or an alloy layer on the front surface of the polymer-based film in a magnetron sputtering mode to form a first bonding layer, wherein the metal layer is one or more of Ni, Ti, W, Cr and Cu, and the alloy layer is one or more of nickel alloy, titanium alloy, tungsten alloy, chromium alloy and copper alloy;
on the first bonding layer, a process layer is made of copper through electro-plating;
on the process layer, a transition layer is made of copper through magnetron sputtering;
fabricating the copper metal layer by electro-plating using copper over the transition layer;
manufacturing a protective layer on the copper metal layer, wherein the protective layer is made of an organic material or an inert metal; the organic material comprises benzotriazole and any one of derivatives thereof, wherein the derivatives comprise 5-carboxyl benzotriazole or benzotriazole-5-octyl carboxylate; wherein the inert metal comprises any one or combination of more of Sn, Cr, Zn or Ni;
preparing an aluminum oxide layer or a silicon compound layer on the back of the polymer base film by means of physical vapor deposition or chemical vapor deposition to form a second bonding layer, wherein the aluminum oxide layer is AlOxWherein x is a real number between 1.0 and 1.5, and the silicon compound layer is SiC or Si3N4Or SiOyAnd the value of y is a real number between x and 2, wherein the x is more than or equal to 1.5;
one or more combined layers are manufactured on the second bonding layer to form the aluminum metal layer, and the method for manufacturing the combined layers comprises the steps of manufacturing the aluminum metal layer in an evaporation plating mode, carrying out plasma oxidation on the aluminum metal layer to form a surface oxidation layer, and then manufacturing the aluminum metal layer on the surface of the surface oxidation layer in an evaporation plating mode;
an aluminum oxide layer is manufactured on the aluminum metal layer in an evaporation plating mode, and the aluminum oxide layer is made of AlOxAnd the value of x is a real number which is more than or equal to 1.0 and less than or equal to 1.5.
10. A lithium ion battery comprising a bipolar current collector according to any one of claims 1 to 7 and a separator stacked, and an electrode active material is attached to a surface of the bipolar current collector.
CN202110574110.9A 2021-05-25 2021-05-25 Lithium ion battery, bipolar current collector and manufacturing method thereof Pending CN113270589A (en)

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Application publication date: 20210817