CN114068867A - Lithium-supplementing negative plate and lithium ion battery - Google Patents

Lithium-supplementing negative plate and lithium ion battery Download PDF

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Publication number
CN114068867A
CN114068867A CN202111408974.XA CN202111408974A CN114068867A CN 114068867 A CN114068867 A CN 114068867A CN 202111408974 A CN202111408974 A CN 202111408974A CN 114068867 A CN114068867 A CN 114068867A
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lithium
coating
negative electrode
carbon
layer
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李云明
和冲冲
柳张雨
杨红新
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Svolt Energy Technology Co Ltd
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Svolt 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
    • H01M4/13—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
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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 invention provides a lithium-supplementing negative plate and a lithium ion battery. The lithium-supplement negative plate comprises: a current collector; the first coating is arranged on one side surface of the current collector and comprises a first active material, and the first active material consists of an alloy negative electrode material and a first carbon negative electrode material; the second coating is arranged on the surface, far away from the current collector, of the first coating and comprises a second active material, and the second active material is a second carbon negative electrode material; and the lithium supplement layer is arranged on the surface of the second coating layer far away from the first coating layer. Because set up the second coating that contains carbon negative pole material between first coating and mend the lithium layer, avoided having alloy negative pole material's first coating surface and mended lithium layer direct contact to reduce or even eliminate the heat that releases because of the lithium embedding reaction that metal lithium and alloy negative pole take place in mending the lithium process, avoid mending the lithium process because metal lithium and alloy negative pole material generate heat the risk of catching fire that seriously causes.

Description

Lithium-supplementing negative plate and lithium ion battery
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium-supplementing negative plate and a lithium ion battery.
Background
The lithium ion battery has the advantages of high energy density, long cycle life, no memory effect and the like, so that the lithium ion battery becomes the first choice of consumer electronic batteries and new energy automobile power batteries. However, lithium loss caused by the formation of a Solid Electrolyte Interface (SEI) film in the first charge-discharge process of the lithium ion battery electrode material limits the exertion of the energy density of the lithium ion battery, the performance is particularly obvious in a silicon-based negative electrode material system, the cycle life is shortened due to active lithium loss caused by side reaction in the cycle process, and lithium supplement to the electrode plate is an effective means for improving the energy density and the cycle life of the lithium ion battery.
The addition of metal lithium on the surface of the negative electrode is the most effective lithium supplement technical scheme, and two lithium supplement technologies of lithium powder and a lithium belt are mainly used at present. According to the application, the research shows that the alloy negative electrode can generate lithium intercalation reaction and generate heat when being in contact with lithium, and spontaneous combustion can be realized when heat accumulation is serious, so that the safety risk is brought to lithium supplement for the alloy negative electrode.
Disclosure of Invention
The invention mainly aims to provide a lithium supplement negative plate and a lithium ion battery, and aims to solve the problem that an alloy negative electrode in the prior art generates heat seriously in the lithium supplement process.
In order to achieve the above object, according to one aspect of the present invention, there is provided a lithium-supplement negative electrode sheet comprising: a current collector; the first coating is arranged on one side surface of the current collector and comprises a first active material, and the first active material consists of an alloy negative electrode material and a first carbon negative electrode material; the second coating is arranged on the surface, far away from the current collector, of the first coating and comprises a second active material, and the second active material is a second carbon negative electrode material; and the lithium supplement layer is arranged on the surface of the second coating layer far away from the first coating layer.
Further, the alloy negative electrode material is selected from any one or more of Si, Sn, SiOx, SnOy, Si alloy and Sn alloy, wherein 0.5< x <1.5 and 0.5< y <1.5, and preferably, the first carbon negative electrode material and the second carbon negative electrode material are independently selected from any one or more of natural graphite, artificial graphite, mesocarbon microbeads, soft carbon and hard carbon.
Further, the thickness of the first coating is 20 to 100 μm, preferably 30 to 80 μm; the thickness of the second coating is 10 to 80 μm, preferably 20 to 50 μm.
Further, the porosity of the first coating is larger than the porosity of the second coating, preferably the porosity of the first coating is 30% to 50%, and preferably the porosity of the second coating is 20% to 40%.
Further, the first coating and/or the second coating further comprises a conductive agent and a binder, preferably, the conductive agent of the first coating and/or the second coating is/are independently selected from one or more of acetylene black, conductive carbon black, carbon fiber, carbon nanotube and ketjen black; preferably, the binder of the first coating layer and/or the second coating layer is/are independently selected from one or more of styrene-butadiene rubber, sodium carboxymethyl cellulose, polyvinylidene fluoride, polytetrafluoroethylene, fluorinated rubber, polyurethane, polyacrylic acid, sodium polyacrylate, polyvinyl alcohol, alginic acid and sodium alginate.
In the first coating, the mass parts of the alloy negative electrode material are 2-50 parts, preferably 5-20 parts, the mass parts of the first carbon negative electrode material are 46-94 parts, preferably 76-91 parts, the mass parts of the binder are 2-3 parts, and the mass parts of the conductive agent are 0.1-1 part.
Furthermore, in the second coating, the mass parts of the second carbon negative electrode material are 96-98, the mass parts of the binder are 2-3, and the mass parts of the conductive agent are 0-1.
Further, the thickness of the lithium supplement layer is 1 to 10 μm.
Further, the lithium supplement layer is a vapor deposition layer, a lithium powder coating layer, a lithium foil or electrochemical lithium supplement.
According to another aspect of the present invention, there is provided a lithium battery comprising a positive electrode, a separator, a negative electrode and an electrolyte, wherein the negative electrode is the lithium-supplementing negative electrode sheet of any one of the above.
By applying the technical scheme of the invention, the second coating containing the carbon cathode material is arranged between the first coating and the lithium supplement layer, so that the direct contact between the surface of the first coating with the alloy cathode material and the lithium supplement layer is avoided, the heat released by lithium intercalation reaction generated between metal lithium and the alloy cathode in the lithium supplement process is reduced or even eliminated, and the fire risk caused by serious heating of the metal lithium and the alloy cathode material in the lithium supplement process is avoided. Therefore, the hidden danger of spontaneous combustion caused by heating of the lithium ion battery applying the lithium supplement negative plate is reduced, and the use safety is greatly improved.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.
As analyzed in the background of the present application, the lithium insertion reaction and heat generation occur when the alloy negative electrode contacts with lithium in the lithium supplement layer of the negative electrode sheet in the prior art, and the problem of heat accumulation is serious. In order to solve the problem, the application provides a lithium supplement negative plate and a lithium ion battery.
In an exemplary embodiment of the present application, there is provided a lithium-supplement negative electrode sheet including: the lithium ion battery comprises a current collector, a first coating, a second coating and a lithium supplement layer, wherein the first coating is arranged on one side surface of the current collector and comprises a first active material, and the first active material is composed of an alloy negative electrode material and a first carbon negative electrode material; the second coating is arranged on the surface, far away from the current collector, of the first coating and comprises a second active material, and the second active material is a second carbon negative electrode material; the lithium supplement layer is arranged on the surface of the second coating layer far away from the first coating layer.
This application has avoided having alloy anode material's first coating surface and mend lithium layer direct contact owing to set up the second coating that contains carbon anode material between first coating and the benefit lithium layer to reduce or even eliminate the heat of giving out because of the lithium reaction of inlaying that metal lithium and alloy cathode take place among the benefit lithium process, avoid mending the lithium process because metal lithium and alloy anode material generate heat the risk of starting a fire that seriously leads to the fact. Therefore, the hidden danger of spontaneous combustion caused by heating of the lithium ion battery applying the lithium supplement negative plate is reduced, and the use safety is greatly improved.
The alloy cathode material is selected from any one or a mixture of more of Si, Sn, SiOx, SnOy, Si alloy and Sn alloy, wherein 0.5< x <1.5 and 0.5< y <1.5, and the theoretical lithium storage capacity, the cycle performance and the safety of the cathode material are comprehensively considered.
The first carbon anode material and the second carbon anode material may be selected from carbon anode materials commonly used in the prior art, for example, the first carbon anode material and the second carbon anode material are independently selected from one or more of natural graphite, artificial graphite, mesocarbon microbeads, soft carbon and hard carbon. The natural graphite and the artificial graphite have the characteristics of high crystallinity, stable layered structure, suitability for lithium intercalation-deintercalation and the like, the soft carbon has larger specific surface area, more stable crystal structure and stronger electrolyte adaptability, and is particularly suitable for being applied to a negative electrode material of a power battery, and the hard carbon has better cycle performance and can be applied to a power-up lithium ion battery. The carbon negative electrode materials can also be used in combination to adapt to different types of lithium ion batteries. The first carbon negative electrode material and the second carbon negative electrode material can be the same or different, the compatibility of the first coating and the second coating can be improved when the first carbon negative electrode material and the second carbon negative electrode material are the same, the advantages of different types of carbon negative electrode materials can be comprehensively utilized when the first carbon negative electrode material and the second carbon negative electrode material are different, and the comprehensive electrical property of the lithium-supplement negative electrode piece is improved.
The thickness of the electrode is also an important parameter influencing the efficiency of the lithium-supplementing negative plate, the thicker the electrode thickness is, the longer the diffusion path of liquid-phase ions is, the higher the diffusion impedance of the electrolyte is, and the poorer the rate performance of the battery is, on the contrary, the too thin electrode thickness is, the low electrode capacity is, and the use requirement is difficult to meet. The thickness of the first coating and the thickness of the second coating of the present application can be referred to the coating thickness conventional in the art. The first coating is provided with an alloy negative electrode material and a first carbon negative electrode material, and the expansion rate of the alloy negative electrode material is relatively high, so that the thickness of the alloy negative electrode material can be reduced properly after the second coating is arranged, in some embodiments of the application, the thickness of the first coating of the lithium-supplement negative electrode sheet is preferably 20-100 μm, and more preferably 30-80 μm. In order to further improve the isolation effect of the second coating on the first coating and the lithium supplement layer and simultaneously enable the activity of the first coating to be fully exerted, the thickness of the second coating is preferably 10-80 μm, and the thickness of the second coating is preferably 20-50 μm.
In order to improve the liquid storage capacity of the lithium-supplement negative pole piece as much as possible and reserve enough space for the expansion of the active materials, the first coating and the second coating are both porous coatings which are the same as the negative pole coatings in the prior art. In some embodiments of the present application, the first coating porosity is greater than the second coating porosity. The porosity of the first coating is preferably 30% to 50%, and the porosity of the second coating is preferably 20% to 40%. The solid content of the coating slurry of the first coating and the second coating is controlled to realize the adjustment of porosity, and enough space is reserved for the expansion of the alloy cathode material by setting higher porosity on the first coating.
In some embodiments, the first coating and/or the second coating further comprises a conductive agent and a binder. The use of the above-described conductive agent and binder enables the contact between the first active material and/or the second active material and the current collector to be sufficiently close, and electrons can efficiently reach various positions within the active materials to participate in the electrochemical reaction. Preferably, the conductive agents of the first coating layer and/or the second coating layer are respectively and independently selected from one or more of acetylene black, conductive carbon black, carbon fiber, carbon nanotube and Ketjen black; wherein, the conductive carbon black is selected from one or more of Super P, Super S and 350G. Preferably, the binder of the first coating layer and/or the second coating layer is/are independently selected from one or more of styrene-butadiene rubber, sodium carboxymethyl cellulose, polyvinylidene fluoride, polytetrafluoroethylene, fluorinated rubber, polyurethane, polyacrylic acid, sodium polyacrylate, polyvinyl alcohol, alginic acid and sodium alginate. The conductive agent and the binder are uniformly distributed in the first active material and/or the second active material to sufficiently function.
In other embodiments of the present application, in the first coating, the mass parts of the alloy negative electrode material are 2 to 50 parts, preferably 5 to 20 parts, the mass parts of the first carbon negative electrode material are 46 to 94 parts, preferably 76 to 91 parts, the mass parts of the binder are 2 to 3 parts, and the mass parts of the conductive agent are 0.1 to 1 part; in some embodiments, in the second coating, the second carbon negative electrode material is 96 to 98 parts by mass, the binder is 2 to 3 parts by mass, and the conductive agent is 0 to 1 part by mass. Under the coordination of the above parts by mass, the respective effects of the components are fully exerted and are mutually synergistic, and the energy density and the charge and discharge capacity of the lithium-supplement negative plate are further improved.
The lithium supplement layer can be provided by referring to the prior art. In some embodiments of the present application, the thickness of the lithium supplement layer is 1-10 μm, and preferably, it can be an evaporated lithium layer, a lithium powder coating layer, a lithium foil, or an electrochemical lithium supplement layer.
In another exemplary embodiment of the present application, there is provided a lithium battery including a positive electrode, a separator, a negative electrode, and an electrolyte, wherein the negative electrode is the aforementioned lithium-supplementing negative electrode sheet.
This application has avoided having alloy anode material's first coating surface and mend lithium layer direct contact owing to set up the second coating that contains carbon anode material between first coating and the benefit lithium layer to reduce or even eliminate the heat of giving out because of the lithium reaction of inlaying that metal lithium and alloy cathode take place among the benefit lithium process, avoid mending the lithium process because metal lithium and alloy anode material generate heat the risk of starting a fire that seriously leads to the fact. Therefore, the hidden danger of spontaneous combustion caused by heating of the lithium ion battery applying the lithium supplement negative plate is reduced, and the use safety is greatly improved.
The advantageous effects of the present application will be further described below with reference to examples and comparative examples.
Example 1
(1) The alloy cathode material in the first active material is SiO, the first carbon cathode material is artificial graphite, and the two components in the first active material are uniformly mixed. The adhesive is styrene butadiene rubber and sodium carboxymethylcellulose in a ratio of 1:1, the conductive agent is carbon black and a single-walled carbon tube in a ratio of 10:1, and the SiO, the artificial graphite, the adhesive and the conductive agent are uniformly mixed with solvent water in a mass ratio of 28.8:67.2:3:1 to prepare negative electrode slurry 1, wherein the solid content is 45%.
(2) In the second active material, the second carbon negative electrode material is artificial graphite, the binder is styrene butadiene rubber and sodium carboxymethyl cellulose in a ratio of 1:1, the conductive agent is carbon black, and the second active material, the binder and the conductive agent are uniformly mixed with a solvent according to a mass ratio of 96:3:1 to prepare negative electrode slurry 2 with a solid content of 55%.
(3) Coating the negative electrode slurry 1 and 2 on one side surface of a negative current collector copper foil by using a double-coating die, and baking the copper foil in an oven at 85 ℃ (baking in a continuous oven) to prepare an initial negative electrode plate; the negative pole piece is compacted after rolling, and the density is 1.5g/cm3The first coating thickness was 70 μm and the porosity was 40%, the second coating thickness was 30 μm and the porosity was 30%.
(4) And compounding the metal lithium foil on the surface of the negative plate in a rolling compounding manner to obtain the lithium-supplementing negative plate, wherein the thickness of the metal lithium foil is 4 microns.
Example 2
The difference from example 1 is that the thickness of the first coating layer is 20 μm.
Example 3
The difference from example 1 is that the thickness of the first coating layer is 100 μm.
Example 4
The difference from example 1 is that the thickness of the first coating layer is 15 μm and the thickness of the second coating layer is 90 μm.
Example 5
The difference from example 1 is that the thickness of the first coating layer is 30 μm.
Example 6
The difference from example 1 is that the thickness of the first coating layer is 80 μm.
Example 7
The difference from example 1 is that the thickness of the second coating layer is 20 μm.
Example 8
The difference from example 1 is that the thickness of the second coating layer is 50 μm.
Example 9
The difference from example 1 is that the thickness of the second coating layer is 10 μm.
Example 10
The difference from example 1 is that the thickness of the second coating layer is 80 μm.
Example 11
The difference from example 1 is that the solids content of slurry 1 is 50% and the porosity of the first coating is 30%.
Example 12
The difference from example 1 is that the solids content of slurry 1 is 40% and the porosity of the first coating is 50%.
Example 13
The difference from example 1 is that the solids content of slurry 2 is 60% and the porosity of the second coating is 20%.
Example 14
The difference from example 1 is that the solids content of slurry 2 is 50% and the porosity of the second coating is 40%.
Example 15
The difference from example 1 is that the solids content of slurry 1 is 53% and the porosity of the first coating is 25%.
Example 16
(1) The alloy negative electrode material in the first active material is Sn, the first carbon negative electrode material is artificial graphite, and the two components in the first active material are uniformly mixed. The adhesive is polyvinylidene fluoride, the conductive agent is carbon fiber, and Sn, artificial graphite, the adhesive and the conductive agent are uniformly mixed with solvent water according to the mass ratio of 19.2:76.8:2:1 to prepare negative electrode slurry 1, wherein the solid content of the slurry is 45%.
(2) In the second active material, the second carbon negative electrode material is natural graphite, the binder is polyacrylic acid and sodium carboxymethyl cellulose, and the proportion of the polyacrylic acid to the sodium carboxymethyl cellulose is 5: 1, uniformly mixing a second active material, a thickening agent, a binder and a conductive agent with a solvent according to a mass ratio of 96:2:1 to prepare a negative electrode slurry 2, wherein the solid content of the slurry is 50%.
(3) Sequentially coating the negative electrode slurry 1 and the negative electrode slurry 2 on one side surface of a negative current collector copper foil, and baking by an oven at 85 ℃ (baking continuously by the oven) to prepare an initial negative electrode piece; rolled negative electrodeThe pole piece is compacted, and the density is 1.6g/cm3The first coating thickness was 60 μm and the porosity was 40%, the second coating thickness was 40 μm and the porosity was 30%.
(4) And compounding the metal lithium foil on the surface of the negative plate in a rolling compounding manner to obtain the lithium-supplementing negative plate, wherein the thickness of the metal lithium foil is 4 microns.
Example 17
(1) The alloy cathode material in the first active material is SnOyThe first carbon negative electrode material is mesocarbon microbeads, and two components in the first active material are uniformly mixed. The adhesive is polyvinylidene fluoride, the conductive agent is carbon fiber, and SnOyThe mesocarbon microbeads, the binder and the conductive agent are uniformly mixed with solvent water according to the mass ratio of 19.2:76.8:2:1 to prepare cathode slurry 1, wherein the solid content of the slurry is 45%.
(2) In the second active material, the second carbon negative electrode material is hard carbon, the binder is polyacrylic acid and sodium carboxymethyl cellulose, and the proportion of the polyacrylic acid to the sodium carboxymethyl cellulose is 5: 1, uniformly mixing a second active material, a thickening agent, a binder and a conductive agent with a solvent according to a mass ratio of 96:2:1 to prepare a negative electrode slurry 2, wherein the solid content of the slurry is 50%.
(3) Sequentially coating the negative electrode slurry 1 and the negative electrode slurry 2 on one side surface of a negative current collector copper foil, and baking by an oven at 85 ℃ (baking continuously by the oven) to prepare an initial negative electrode piece; the negative pole piece is compacted after rolling, and the density is 1.6g/cm3The first coating thickness was 60 μm and the porosity was 40%, the second coating thickness was 40 μm and the porosity was 30%.
(4) And compounding the metal lithium foil on the surface of the negative plate in a rolling compounding manner to obtain the lithium-supplementing negative plate, wherein the thickness of the metal lithium foil is 4 microns.
Comparative example 1
The difference from example 1 is that: (3) and uniformly mixing the two slurries according to the final surface density ratio of coating, and coating the mixture on a copper foil current collector. The thickness is 100 μm and the porosity is 35%.
Comparative example 2
The difference from example 3 is that: (3) and uniformly mixing the two slurries according to the final surface density ratio of coating, and coating the mixture on a copper foil current collector. The thickness is 100 μm and the porosity is 35%.
The 200m lithium-supplement negative electrode roll of the above embodiment and the comparative example is coiled for five minutes, then the temperature of the middle part of the electrode roll is tested, and the electrode sheets are assembled into a soft package lithium ion battery with the same 5Ah, the positive electrode is ternary NCM811, and the electrolyte is LiPF (electro magnetic compatibility) with EMC (electro magnetic compatibility) and FEC (Forward error correction) of 2:7:16The results of measuring the temperature rise and the expansion rate of the electrode sheet after the electrolyte is fully charged at 0.33C are shown in the following table 1.
TABLE 1
Figure BDA0003373232840000061
Figure BDA0003373232840000071
It can be seen from the above examples and comparative examples that the two coatings are disposed on the lithium supplement negative electrode plate, so that the calorific value of the alloy reaction process caused by direct contact between metal lithium and the alloy negative electrode material in the lithium supplement process can be effectively reduced or eliminated, and even if the same components as those in the present application are used, the calorific value reduction effect of the present application is difficult to achieve without layering.
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects: because set up the second coating that contains carbon negative pole material between first coating and mend the lithium layer, avoided having alloy negative pole material's first coating surface and mended lithium layer direct contact to reduce or even eliminate the heat that releases because of the lithium embedding reaction that metal lithium and alloy negative pole take place in mending the lithium process, avoid mending the lithium process because metal lithium and alloy negative pole material generate heat the risk of catching fire that seriously causes. Therefore, the hidden danger of spontaneous combustion caused by heating of the lithium ion battery applying the lithium supplement negative plate is reduced, and the use safety is greatly improved.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A lithium supplement negative plate is characterized by comprising:
a current collector;
a first coating disposed on one side surface of the current collector, the first coating including a first active material consisting of an alloy negative electrode material and a first carbon negative electrode material;
a second coating disposed on a surface of the first coating distal from the current collector, the second coating comprising a second active material, the second active material being a second carbon negative electrode material;
and the lithium supplement layer is arranged on the surface of the second coating layer far away from the first coating layer.
2. The lithium-supplementing negative electrode sheet according to claim 1, wherein the alloy negative electrode material is selected from any one or more of Si, Sn, SiOx, SnOy, Si alloy, and Sn alloy, wherein 0.5< x <1.5 and 0.5< y <1.5, and preferably the first carbon negative electrode material and the second carbon negative electrode material are each independently selected from any one or more of natural graphite, artificial graphite, mesocarbon microbeads, soft carbon, and hard carbon.
3. The lithium-supplementing negative plate according to claim 1, wherein the thickness of the first coating is 20 to 100 μm, preferably 30 to 80 μm; the thickness of the second coating is 10-80 μm, and preferably the thickness of the second coating is 20-50 μm.
4. The lithium negative electrode plate according to any one of claims 1 to 3, wherein the porosity of the first coating is greater than the porosity of the second coating, preferably the porosity of the first coating is 30% to 50%, and preferably the porosity of the second coating is 20% to 40%.
5. The lithium supplement negative electrode sheet according to any one of claims 1 to 4, wherein the first coating layer and/or the second coating layer further comprises a conductive agent and a binder, preferably the conductive agent of the first coating layer and/or the second coating layer is/are each independently selected from one or more of acetylene black, conductive carbon black, carbon fiber, carbon nanotube, Ketjen black; preferably, the binder of the first coating and/or the second coating is/are independently selected from one or more of styrene-butadiene rubber, sodium carboxymethylcellulose, polyvinylidene fluoride, polytetrafluoroethylene, fluorinated rubber, polyurethane, polyacrylic acid, sodium polyacrylate, polyvinyl alcohol, alginic acid and sodium alginate.
6. The lithium-supplement negative electrode sheet according to claim 5, wherein in the first coating, the mass parts of the alloy negative electrode material are 2-50 parts, preferably 5-20 parts, the mass parts of the first carbon negative electrode material are 46-94 parts, preferably 76-91 parts, the mass parts of the binder are 2-3 parts, and the mass parts of the conductive agent are 0.1-1 part.
7. The lithium-supplement negative electrode sheet according to claim 5, wherein the second coating layer comprises 96 to 98 parts by mass of the second carbon negative electrode material, 2 to 3 parts by mass of the binder, and 0 to 1 part by mass of the conductive agent.
8. The lithium supplement negative electrode sheet according to any one of claims 1 to 7, wherein the thickness of the lithium supplement layer is 1 to 10 μm.
9. The negative lithium supplement sheet according to claim 1, wherein the lithium supplement layer is a vapor deposition layer, a lithium powder coating layer, a lithium foil, or an electrochemical lithium plating layer.
10. A lithium battery comprising a positive electrode, a separator, a negative electrode and an electrolyte, wherein the negative electrode is the lithium-supplementing negative electrode sheet according to any one of claims 1 to 8.
CN202111408974.XA 2021-11-24 2021-11-24 Lithium-supplementing negative plate and lithium ion battery Pending CN114068867A (en)

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