CN116759537B - Lithium battery negative electrode and preparation method and application thereof - Google Patents

Lithium battery negative electrode and preparation method and application thereof Download PDF

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CN116759537B
CN116759537B CN202311016323.5A CN202311016323A CN116759537B CN 116759537 B CN116759537 B CN 116759537B CN 202311016323 A CN202311016323 A CN 202311016323A CN 116759537 B CN116759537 B CN 116759537B
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lithium
area
buffer layer
belt
stress buffer
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CN116759537A (en
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郇庆娜
孙兆勇
孔德钰
贾海涛
陈强
牟瀚波
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China Energy Lithium Co ltd
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China Energy Lithium 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/533—Electrode connections inside a battery casing characterised by the shape of the leads or tabs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/534—Electrode connections inside a battery casing characterised by the material of the leads or tabs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The application provides a lithium battery cathode, a preparation method and application thereof. The lithium battery cathode of the application consists of an elongated lithium or lithium alloy strip and a current collecting and collecting part combined on at least one side edge of the elongated lithium or lithium alloy strip, wherein the at least one side edge of the lithium or lithium alloy strip is provided with a pretreatment area, the current collecting and collecting part comprises an area with a stress buffer layer, and the pretreatment area and the area with the stress buffer layer are mutually covered.

Description

Lithium battery negative electrode and preparation method and application thereof
Technical Field
The application relates to the technical field of electrochemical energy storage, in particular to a lithium negative electrode for a metal lithium battery, a preparation method and application thereof.
Background
As society demands higher and higher energy densities for lithium ion batteries. First, a higher specific capacity negative electrode material is used, and metallic lithium is considered to be the optimal negative electrode material due to the capacity of 3860 mAh/g and a low potential of-3.04V. At present, many battery manufacturers directly use pure metal lithium strips as cathodes, the thickness of the metal lithium is 50-80 mu m, the metal lithium is very soft, and the thickness of the metal lithium is less than 100 mu m, so that the metal lithium is coiled into a coilThe difficulty of chemical production is great, and the difficulty of leading out the tab by coiling the metal lithium strip is greater. CN209641727 patent discloses that metal lithium is die-cut into a piece of negative electrode plate, then copper tab is attached to the single piece of electrode plate by adopting the pressure of 0.3-0.5 MPa to lead out tab, and the lead out tab by adopting the process is time-consuming and labor-consuming, and cannot be produced and applied on a large scale. In other scientific research institutes, a lithium copper covered belt is used as a negative electrode, and the density of copper is 8.96g/cm 3 The density of the lithium metal is 16 times that of the lithium metal, the 6um copper foil is equivalent to lithium with the thickness of 100um, and the specific energy of the product adopting the whole copper foil to cover the lithium metal is limited, so that the existing negative electrode can not meet the requirement of a high specific energy battery.
Disclosure of Invention
The application provides a novel metal lithium negative electrode, wherein the binding area of the tab and the lithium belt in the lithium negative electrode is very narrow, the occupied proportion is very small, the specific energy of a battery is greatly improved, the tab leading-out mode is relatively convenient, and the lithium negative electrode can be rolled for large-scale batch production and use.
Most of the current lithium copper cladding processes use a pressure cladding process. The inventor of the application discovers that when the copper foil is only covered on the edge of the lithium strip as a tab, the action force only acts on the narrow covered area because the covered area of the copper and the lithium is very narrow (3-10 mm), the pressure is small during covering, the adhesion of the lithium and the copper is poor, the lithium is easily stripped from the copper, and the current collecting effect is poor; the lithium material in the covered region is correspondingly stretched, but the lithium material in other uncovered regions is not stressed and is not stretched, and in the coiling production process of the metal lithium anode product, the lithium in the covered region and the lithium in the uncovered region are inconsistent in length (the inconsistency is more obvious along with the increase of the length), so that the phenomenon of stretching deformation of the lithium in the uncovered region is caused.
In view of the above problems, the inventors have devised a stress buffer layer provided in a region where a tab is to be bonded to a lithium strip, the stress buffer layer being composed of raised discontinuous metal particles which are extendably deformed (the height of the raised particles becomes small) by an external force when the tab is bonded to the lithium strip, so that stress generated at the time of bonding can be released by buffering, and extension of lithium material in the bonded region by the stress is reduced or avoided. In addition, the area where the lithium strip is to be combined with the tab can be pretreated to form a thickness thinning pretreatment area, the pretreatment area is provided with a new metal lithium surface (the original lithium surface is provided with a passivation layer which is unfavorable for the combination of lithium and copper), the stress buffer layer and the lithium strip are better combined together, and meanwhile, raised particles in the stress buffer layer can fill the thinning area after deformation, so that the metal lithium cathode with the tab is flat in surface.
The technical scheme of the application is as follows.
One aspect of the present application provides a lithium battery anode consisting of an elongated lithium or lithium alloy strip and a current collecting and collecting part bonded to at least one side edge of the elongated lithium or lithium alloy strip, wherein at least one side edge of the lithium or lithium alloy strip has a pre-treated region, the current collecting and collecting part includes a region having a stress buffer layer, and the pre-treated region and the region having a stress buffer layer are overlaid with each other.
According to one embodiment, the current collecting and collecting portion further includes a portion extending beyond the width of the lithium or lithium alloy strip, which is not covered with the pretreatment region, and which is die-cut into tabs.
According to one embodiment, the metallic lithium strip or lithium alloy strip has a thickness of 0.01-0.15mm and a width of 10-1500mm. Preferably, the metallic lithium strip or lithium alloy strip has a thickness of 0.01-0.10mm, more preferably 0.010-0.05mm; the width of the metallic lithium strip or lithium alloy strip is 20-1500mm, more preferably 50-1500mm, for example 150-1500mm,200-1500mm,250-1500mm,300-1500mm,350-1500mm,400-1500mm,450-1500mm, or 500-1500mm.
According to one embodiment, the width of the pre-treatment area is 2-10mm, the thickness of the pre-treatment area being 0.1-5um thinner than elsewhere, preferably 1-5um; pretreatment modes comprise erasing, roller removing and gluing.
According to one embodiment, the lithium alloy comprises a binary alloy and/or a multi-element alloy, preferably a binary alloy and/or a ternary alloy.
According to one embodiment, the lithium alloy is formed by combining metallic lithium with any one or at least two elements of Ag, au, sn, si, zn, al, mg, in, ga, B, mn, sb, cr, V, cu, fe or Ti, and the mass ratio of the metallic lithium in the lithium alloy may be 50% or more, preferably 70% or more, more preferably 80% or more, even 90% or more.
According to one embodiment, the current collecting and collecting part is made of a metal foil selected from copper foil, nickel foil, stainless steel foil or composite metal current collector; the foil thickness is 3-10um, preferably 3-8um.
According to one embodiment, the width of the current collecting and collecting part is 12-30mm; the stress buffer layer has a width of 2-10mm.
According to one embodiment, the stress buffer layer comprises discontinuous raised metal particles formed by vapor deposition, the metal particles having a particle size of 1-7um, preferably 1-5um. The height of the bulges of the metal particles is 1-5um; the area ratio of the metal particles in the stress buffer layer is 1:3 to 9:10.
according to one embodiment, the metal particles include at least one of tin particles, zinc particles, magnesium particles, aluminum particles, silver particles, and lithium particles.
According to one embodiment, the metal particles are of the same kind as the alloying elements contained in the lithium alloy strip.
According to one embodiment, the metal particles are of a different kind than the alloying elements contained in the lithium alloy strip.
According to one embodiment, the pre-treated region and the region of the current collector portion having the stress buffering layer are bonded together by means of at least one of a diffusion welding, ultrasonic welding, resistance welding, pressure welding process; the width of the overlap region ranges from 2 to 10mm.
According to one embodiment, the region where the stress buffer layer of the current collecting and collecting portion and the lithium or lithium alloy ribbon overlap may be continuous or discontinuous; because the atoms are constantly diffusing, the discontinuous regions will subsequently diffuse to a uniform state. For example, the stress buffer layer of the current collecting and collecting portion may be divided into discrete portions, each of which is spaced apart by a distance, for example, 0.1 to 1mm. The stress buffer layer may also have a mesh shape.
According to one embodiment, the thickness of the stress buffer layer of the current collecting and collecting portion and the lithium or lithium alloy strip coating area is equal to or slightly greater than the thickness of the pure lithium or lithium alloy strip. For example: the thickness of the lithium belt is 50um, and the thickness of the stress buffer layer and the lithium belt covering area of the current collecting and collecting part is 55um; the thickness of the lithium belt is 60um, and the thickness of the stress buffer layer and the lithium belt covering area of the current collecting and collecting part is 60um; the thickness of the lithium-magnesium (magnesium content 10%) alloy strip is 60um, and the thickness of the stress buffer layer and the lithium strip covering area of the current collecting and collecting part is 63um; the thickness of the lithium silver (silver content 1%) alloy strip is 40um, and the thickness of the stress buffer layer and the lithium strip covering region of the current collecting and collecting part is 40um.
Another aspect of the present application provides a method for preparing the negative electrode of the above lithium battery, comprising:
step one: depositing discontinuous raised metal particles on the metal foil through a vapor deposition process to obtain a current collecting and converging part with partial areas covered with a stress buffer layer;
step two: pre-treating at least one side edge area of the lithium belt or the lithium alloy belt by at least one of erasing, roller removing and gluing to form a pre-treated area with the width of 2-10 mm;
step three: welding the area with the stress buffer layer of the current collecting and collecting part obtained in the first step and the pretreatment area of the lithium belt or the lithium alloy belt obtained in the second step together by means of at least one of diffusion welding, ultrasonic welding, resistance welding and pressure welding, so that the metal particles of the stress buffer layer and the lithium in the lithium belt or the lithium alloy belt are fused together to form a fusion area of the lithium and the metal particles; and
optional step four: and die-cutting the part, which is not covered with the pretreatment area, of the current collecting and converging part and extends beyond the width of the lithium strip or the lithium alloy strip to form the tab.
According to one embodiment, in the first step, a conductive foil of a current collecting and converging part is subjected to low-temperature plasma degreasing treatment; and drying the deoiled conductive foil, and depositing discontinuous raised metal lithium particles on the dried conductive foil through a vapor deposition process to obtain a stress buffer layer, wherein the width of the stress buffer layer is 2-10mm.
A further aspect of the application provides the use of a high specific energy lithium battery anode as described above in a lithium ion battery, the high specific energy lithium metal anode being useful as the anode of a lithium metal battery.
According to one embodiment, the application provides a lithium battery, which comprises the negative electrode of the lithium battery, wherein the positive electrode material is selected from ternary nickel cobalt manganese materials, ternary nickel cobalt aluminum materials, lithium-rich manganese-based positive electrode materials, lithium cobaltate, lithium iron phosphate and sulfur positive electrode materials.
According to one embodiment, the electrolyte of the lithium battery may be selected from a liquid electrolyte or a solid electrolyte; the liquid electrolyte is selected from esters or ethers; the solid electrolyte may be selected from an oxide solid electrolyte, a sulfide solid electrolyte, or a polymer-based electrolyte, such as PEO (mixed oxide or sulfide powder) based electrolyte.
For the liquid battery, the diaphragm is selected from a PP, PE or a PP and PE three-layer covered diaphragm, and the diaphragm can be provided with a ceramic coating.
The battery can be formed into square, soft package or cylindrical batteries.
The application has at least one of the following advantages:
(1) The high specific energy metal lithium cathode can be produced in batch in a coiled mode, and the problem that the engineering of the pure lithium belt cathode is difficult to lead out the tab is solved.
(2) The high specific energy metal lithium cathode provided by the application is provided with the tab, and the tab can be directly die-cut for use without additional tab extraction.
(3) The high specific energy metal lithium cathode can be directly used as a cathode, and the cathode is matched with a high-capacity cathode material to prepare a battery with energy density of over 500wh/kg because of small using area of a current collecting and converging part and small occupied specific gravity.
(4) The problem of the infirm that lithium and collection portion cover and close is solved, the stress buffer layer can closely contact with lithium area or lithium alloy area, and the collection effect is good.
Drawings
Fig. 1 is a schematic view of a planar structure of a negative electrode of a lithium battery according to the present application;
FIG. 2 is a cross-sectional view of a negative electrode of a lithium battery of the present application, wherein the thickness of the lithium and current collecting and collecting part is greater than the thickness of the lithium strip or the lithium alloy strip;
FIG. 3 is another cross-sectional view of a negative electrode of a lithium battery of the present application, wherein the thickness of the lithium and current collecting and collecting part is equal to the thickness of the lithium strip or the lithium alloy strip;
FIG. 4 is a physical diagram of lithium metal particles in the stress buffer layer in example 2;
FIG. 5 is a physical view of magnesium metal particles in the stress buffer layer of example 5.
Detailed Description
The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application. In addition, the technical features of the embodiments of the present application described below may be combined with each other as long as they do not collide with each other.
Also, the various product structural parameters, various reaction participants and process conditions employed in the following examples are typical examples, but a great deal of experiments by the inventor prove that the above-listed other different structural parameters, other types of reaction participants and other process conditions are applicable and can achieve the technical effects claimed in the application.
Fig. 1 is a schematic view (plan view) of a planar structure of a lithium battery anode of the present application, wherein the lithium battery anode includes a lithium strip or lithium alloy strip 1 and a current collecting and collecting part 2 bonded to one side edge of the lithium strip or lithium alloy strip. Fig. 2 and 3 show a cross-sectional view of a lithium battery anode according to the application, wherein the pretreated region of the lithium strip or lithium alloy strip 1 is joined to the region of the current collector 2 with the stress buffer layer to form a joint 3 (fusion zone of lithium and metal particles). The thickness of the cladding region in fig. 2 is greater than the thickness of the lithium or lithium alloy ribbon, and the thickness of the cladding region in fig. 3 is equal to the thickness of the lithium or lithium alloy ribbon.
Example 1
The thickness of the coiled copper foil (current collecting and collecting part) is 5um, and the width is 20mm; at a vacuum degree of 10 -3 Under the condition of Pa and 500 ℃, depositing lithium particles with the particle size of 2um on the surface of one side edge area (3 mm width area) of the copper foil, wherein the area ratio of the lithium particles is one half, so as to obtain a stress buffer layer;
the method comprises the steps of performing erasure treatment on an edge area (3 mm wide) on one side of a rolled lithium belt (50 um thick and 100mm wide), wherein the erasure thickness is 1um; and welding the stress buffer layer area on the copper foil and the lithium belt erasing area together by means of pressure welding (the pressure is 50MPa and the temperature is 40 ℃) to obtain the lithium anode with the thickness of the lithium copper cladding area being 55 um. In the lithium copper composite tape obtained in the example, the surface of the lithium tape was flat.
Example 2
The thickness of the coiled copper foil (current collecting and collecting part) is 3.5um, and the width is 15mm; at a vacuum degree of 10 -3 Under Pa, the temperature is 500 ℃, lithium particles with the particle size of 1um are deposited on the surface of one side edge area (5 mm width area) of the copper foil, and the area ratio of the lithium particles is three fifths, so that a stress buffer layer is obtained; fig. 4 shows a physical view of lithium metal particles in the stress buffer layer in this example.
Carrying out roller removal treatment on an edge area (5 mm wide) on one side of a rolled lithium belt (60 um thick and 200mm wide), wherein the thickness of the roller removal treatment is 4um; and welding the stress buffer layer area on the copper foil and the roller removing area of the lithium belt together by a pressure welding mode (the pressure is 80MPa and the temperature is 30 ℃) to obtain the lithium anode with the thickness of the lithium copper cladding area of 60 um.
Example 3
The thickness of the coiled copper foil (current collecting and collecting part) is 4um, and the width is 20mm; at a vacuum degree of 10 -3 Under Pa, the temperature is 500 ℃, lithium particles with the particle size of 1um are deposited on the surface of a copper foil (3 mm width area), and the area ratio of the lithium particles is one half, so that a stress buffer layer is obtained;
the method comprises the steps of performing erasure treatment on an edge area (3 mm wide) on one side of a rolled lithium belt (50 um thick and 500mm wide), wherein the erasure thickness is 3um; and welding the stress buffer layer area on the copper foil and the erasing area of the lithium belt together by means of pressure welding (the pressure is 40MPa and the temperature is 30 ℃) to obtain the lithium anode with the thickness of the lithium copper cladding area of 50 um.
Example 4
The thickness of the coiled stainless steel foil (current collecting and converging part) is 10um, and the width is 20mm; at a vacuum degree of 10 -5 Under the condition of Pa and 1000 ℃, tin particles with the particle size of 1um are deposited on the surface of the stainless steel foil (5 mm width area), and the area ratio of the tin particles is one half, so that a stress buffer layer is obtained;
carrying out roller removal treatment on an edge area (5 mm wide) on one side of a rolled lithium tin alloy belt (60 um thick, 300mm wide and tin content of 5 percent), wherein the thickness of the roller removal is 3um; and welding a stress buffer layer area on the stainless steel foil and a roller removing area of the lithium tin alloy belt together by means of pressure welding (the pressure is 80MPa and the temperature is 40 ℃), so as to obtain the high specific energy metallic lithium negative electrode product.
Example 5
The thickness of the coiled copper foil (current collecting and collecting part) is 5um, and the width is 20mm; at a vacuum degree of 10 -5 Under the condition of Pa and 700 ℃, magnesium particles with the particle size of 2um are deposited on the surface of a copper foil (3 mm width area), and the area ratio of the magnesium particles is one third, so that a stress buffer layer is obtained; fig. 5 shows a physical view of magnesium metal particles in the stress buffer layer in this example.
The method comprises the steps of performing erasure treatment on an edge area (5 mm wide) of one side of a rolled lithium-magnesium alloy belt (50 um thick, 100mm wide and 10% of magnesium content), wherein the erasure thickness is 3um; and welding a stress buffer layer area on the copper foil and an erasing area of the lithium magnesium alloy belt together by means of pressure welding (the pressure is 60MPa and the temperature is 30 ℃) to obtain the high specific energy metal lithium negative electrode product.
Example 6
The thickness of the coiled copper foil (current collecting and collecting part) is 5um, and the width is 20mm; at a vacuum degree of 10 -5 Under Pa and 700 ℃, magnesium particles with the particle size of 2um are deposited on the surface of the copper foil (3 mm width area), and the area ratio of the magnesium particles is one third, thus obtaining the copper foilA force buffer layer;
the method comprises the steps of performing erasure treatment on an edge area (5 mm wide) on one side of a rolled lithium belt (50 um thick and 300mm wide), wherein the erasure thickness is 3um; and welding the stress buffer layer area on the copper foil and the erasing area of the lithium belt together by means of pressure welding (the pressure is 50MPa and the temperature is 40 ℃), so as to obtain the high specific energy metal lithium negative electrode product.
Example 7
The negative electrode used was the high specific energy metallic lithium negative electrode of example 1; the positive electrode uses NCM ternary positive electrode, and is dried for 12 hours at 130 ℃ to be used as a battery; the diaphragm uses Celgard2500, and the electrolyte adopts 1M LiPF 6 EC: emc=3:7 (vol/vol). The high specific energy lithium metal negative electrode, the NCM ternary positive electrode and the separator of example 1 were assembled into a pouch cell with a capacity of 2Ah by means of a laminator.
The test voltage range is 3-4.25V, and the charge-discharge current is 0.5C.
Example 8
The negative electrode is the high specific energy metal lithium negative electrode of the embodiment 5, the positive electrode is NCM ternary positive electrode, and the battery is prepared by drying at 130 ℃ for 12 hours; the diaphragm uses Celgard2500, and the electrolyte adopts 1M LiPF 6 EC: emc=3:7 (vol/vol). The high specific energy lithium metal negative electrode, the NCM ternary positive electrode and the separator of example 5 were assembled into a pouch cell with a capacity of 2Ah by means of a laminator. The test voltage range is 3-4.25V, and the charge-discharge current is 0.5C.
Comparative example 1
The thickness of the rolled copper foil is 5um, and the width is 20mm; rolled lithium tape (60 um thick), width 100mm; the edge area (3 mm wide) on one side of the copper foil and the edge area (3 mm wide) on one side of the lithium belt are pressed together, the set pressure is 70MPa, the inconsistent length of the lithium belt in the pressed and covered area and the lithium belt area which is not covered and covered is found in the production process of the product, the lithium deformation of the lithium belt area which is not covered and covered is easily pulled in the covered area, when the length of the production product reaches about 20 meters, the tensile deformation of the lithium belt is serious, a plurality of potholes appear on the surface of the lithium belt, the lithium belt cannot be used as a negative electrode, and the winding is stopped.
Comparative example 2
The thickness of the coiled copper foil (current collecting and collecting area) is 5um, and the width is 120mm; the thickness of the lithium belt is 25um, the width of the lithium belt is 100mm, and the lithium belt is covered on the double sides of the rolled copper foil to obtain a product with metal lithium covered on the double sides of the copper foil (the whole copper foil is used as a current collecting and collecting area).
Using the negative electrode, wherein the positive electrode uses NCM ternary positive electrode, and drying at 130 ℃ for 12 hours to prepare a battery; the diaphragm uses Celgard2500, and the electrolyte adopts 1M LiPF 6 EC: emc=3:7 (vol/vol). And assembling the negative electrode, the NCM ternary positive electrode and the diaphragm into a soft package battery by a lamination machine, wherein the capacity of the battery core is 2Ah. The test voltage range is 3-4.25V, and the charge-discharge current is 0.5C.
Table 1: specific energy contrast for assembled batteries with different cathodes
Group of experiments Actual capacity of cell Specific energy of cell (Wh/kg)
Example 7 2.02Ah 512.3
Example 8 1.98Ah 510.8
Comparative example 2 2.01Ah 413.5
As can be seen from Table 1, in examples 7 and 8, which used very narrow copper foil as current collector, specific energy of 500Wh/kg was broken through, and in comparative example 2, the entire copper foil was used as current collector, and the specific energy was only 413.5Wh/kg because the copper foil was large in density and large in area.
It should be understood that the foregoing description is only of the preferred embodiments of the present application and is not intended to limit the application, but is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the application.

Claims (10)

1. A lithium battery cathode is characterized in that, the lithium battery cathode consists of an elongated lithium belt or a lithium alloy belt and a current collecting and gathering part combined on at least one side edge of the elongated lithium belt or the lithium alloy belt, wherein
At least one side edge of the lithium strip or the lithium alloy strip is provided with a pretreatment area, the current collecting and collecting part comprises an area with a stress buffer layer, the pretreatment area and the area with the stress buffer layer are mutually covered together,
wherein, the pretreatment is as follows: the method comprises the steps of preprocessing a region to be combined with a tab of a lithium belt to form a preprocessed region with thinned thickness, wherein the preprocessed region is provided with a new metal lithium surface;
the stress buffer layer is as follows: the stress buffer layer is formed by raised discontinuous metal particles in the region of the tab to be bonded to the lithium strip, the raised particles being ductile under the action of an external force when the tab is bonded to the lithium strip.
2. The lithium battery negative electrode of claim 1, wherein the current collecting and collecting portion further comprises a portion extending beyond the width of the lithium or lithium alloy strip that is not covered by the pretreatment region, the portion being die cut into tabs.
3. The lithium battery anode according to claim 1, wherein the lithium strip or lithium alloy strip has a thickness of 0.01 to 0.15mm and a width of 10 to 1500mm; the width of the pretreatment area is 2-10mm, the thickness of the pretreatment area is 0.1-5um thinner than the thickness of other parts, and the pretreatment mode comprises erasing, roller removal and gluing.
4. The lithium battery negative electrode according to claim 1, wherein the lithium alloy is formed by combining metallic lithium with any one or at least two elements of Ag, au, sn, si, zn, al, mg, in, ga, B, mn, sb, cr, V, cu, fe or Ti.
5. The lithium battery anode according to claim 1, wherein the current collecting and collecting part is made of a metal foil selected from copper foil, nickel foil, stainless steel foil or composite metal current collector;
the thickness of the current collecting and converging part is 3-10um; the width is 12-30mm; the stress buffer layer has a width of 2-10mm.
6. The lithium battery anode according to claim 1, wherein the discontinuous raised metal particles in the stress buffer layer are formed by vapor deposition, the metal particles having a particle size of 1-7um; the height of the bulges of the metal particles is 1-5um; the area ratio of the metal particles in the stress buffer layer is 1:3 to 9:10.
7. the lithium battery negative electrode of claim 6, wherein the metal particles comprise at least one of tin particles, zinc particles, magnesium particles, aluminum particles, silver particles, and lithium particles.
8. The lithium battery anode according to claim 1, wherein the pre-treated region and the region of the current collecting and collecting portion having the stress buffering layer are bonded together by at least one of diffusion welding, ultrasonic welding, resistance welding, pressure welding process; the width of the overlap region ranges from 2 to 10mm.
9. A method of preparing the lithium battery anode of any one of claims 1 to 8, comprising:
step one: depositing discontinuous raised metal particles on the metal foil through a vapor deposition process to obtain a current collecting and converging part with partial areas covered with a stress buffer layer;
step two: pre-treating at least one side edge area of the lithium belt or the lithium alloy belt by at least one of erasing, roller removing and gluing to form a pre-treated area with the width of 2-10 mm;
step three: welding the area with the stress buffer layer of the current collecting and collecting part obtained in the first step and the pretreatment area of the lithium belt or the lithium alloy belt obtained in the second step together by means of at least one of diffusion welding, ultrasonic welding, resistance welding and pressure welding, so that the metal particles of the stress buffer layer and the lithium in the lithium belt or the lithium alloy belt are fused together to form a fusion area of the lithium and the metal particles; and
optional step four: and die-cutting the part, which is not covered with the pretreatment area, of the current collecting and converging part and extends beyond the width of the lithium strip or the lithium alloy strip to form the tab.
10. A lithium battery, characterized in that the lithium battery comprises a lithium battery anode according to any one of claims 1-8, the positive electrode material being selected from the group consisting of ternary nickel cobalt manganese materials, ternary nickel cobalt aluminum materials, lithium-rich manganese-based positive electrode materials, lithium iron phosphate, lithium cobalt oxide and sulfur positive electrode materials.
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CN112956049A (en) * 2018-11-08 2021-06-11 株式会社Posco Metallic lithium negative electrode, method of preparing the same, and lithium secondary battery using the same
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