CN116014069A - Pre-lithiated composite negative electrode plate, preparation method thereof and lithium ion battery - Google Patents
Pre-lithiated composite negative electrode plate, preparation method thereof and lithium ion battery Download PDFInfo
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Abstract
The invention relates to a pre-lithiated composite negative electrode plate, a preparation method and a lithium ion battery, wherein the pre-lithiated composite negative electrode plate comprises a pre-lithiated negative electrode plate and a protective layer, the pre-lithiated negative electrode plate comprises a negative electrode current collector, a membrane layer and a pre-lithiation layer which are sequentially connected, and the protective layer is positioned on the surface of the pre-lithiation layer; the protective layer comprises 85-98% of main component, 0.5-10% of binder and 0.1-5% of conductive agent; the main component is a negative electrode active material and/or an inert material. According to the pre-lithiated composite negative electrode plate, the protective layer is arranged, so that contact reaction of metal lithium in the pre-lithiated layer with moisture and oxygen can be effectively avoided, stability and storage time in the storage process of the electrode plate are improved, dependence on a low-humidity environment is reduced, the problem of sticking of the metal lithium in the rolling process can be effectively avoided, and the first effect of the battery cell prepared based on the pre-lithiated composite negative electrode plate is remarkably improved.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a pre-lithiated composite negative plate, a preparation method and a lithium ion battery.
Background
The electric and novel energy storage of automobiles are rapidly integrated into daily life of people, and the lithium ion batteries are also paid attention to by various research institutions in recent years as the core basis of the electric and energy storage. The lithium ion battery has the advantages of long cycle life, high energy density, good safety and reliability, and the like, but has higher consumption of active lithium for first film formation. In order to further improve the energy density and the cycle life, researchers propose a pre-lithiation design to compensate for the consumption of active lithium caused by the first film formation to improve the energy density, and simultaneously, the consumption of active lithium in the using process can be continuously supplemented to optimize the cycle life.
The method for pre-lithiation of the negative electrode in the prior art comprises the steps of uniformly coating lithium powder on the surface of the negative electrode, pressing the lithium powder to a specific thickness by a tape casting device, compounding a lithium film with a graphite negative electrode, and the like; the positive electrode prelithiation realizes the effect of supplementing lithium by introducing a positive electrode lithium supplementing additive into the positive electrode membrane; in addition, other pre-lithiation technologies including three-electrode lithium supplementing, diaphragm supplementing, electrolyte lithium supplementing and the like are also provided, and the initial efficiency of the battery cell can be greatly improved by utilizing an external lithium source to supplement the film forming consumption of the SEI film.
The current main current negative electrode pre-lithiation means is lithium powder lithium supplement and lithium belt calendaring lithium supplement, and the two modes are that lithium metal with high activity is directly compounded on the surface of a pole piece. The direct surface compounding method has a simple process, but has a plurality of problems, such as high chemical activity of lithium metal, namely lithium powder particles or lithium films, which are compounded on the surface of the pole piece. The pole piece after lithium supplementation has high requirements on the surrounding environment (-humidity above dew point of 50 ℃), which brings a plurality of problems, such as difficult storage of the pole piece, high cost of ultra-low humidity environment, easy ignition of the pole piece in the subsequent processing process, and the like; for example, the lithium metal material on the surface layer of the pole piece after lithium supplementation is softer, so that the pole piece is easy to be stuck to a roller for demoulding when passing the roller in the rolling or subsequent production process, and meanwhile, a high-activity lithium metal simple substance is easy to be corroded by substitution reaction with metal elements such as iron in a steel roller or a pole piece parting knife, so that the production cost is high and the process efficiency is low.
In summary, how to overcome the above problems of the pre-lithiated negative electrode sheet, so that the pre-lithiated negative electrode sheet can be safely and stably stored and does not react with metal elements existing in the steel roller in subsequent production such as rolling to avoid roller sticking, and meanwhile, improving the performance of the electrode sheet is a technical problem to be solved.
Disclosure of Invention
The invention aims to provide a pre-lithiated composite negative electrode plate, a preparation method and a lithium ion battery, so that the pre-lithiated negative electrode plate can be safely and stably stored, the lithium introduced by pre-lithiation is prevented from reacting or sticking to a roller, and the performance of the electrode plate is improved.
In a first aspect, the invention relates to a pre-lithiated composite negative electrode sheet, which comprises a pre-lithiated negative electrode sheet and a protective layer, wherein the pre-lithiated negative electrode sheet comprises a negative electrode current collector, a membrane layer and a pre-lithiated layer which are sequentially connected, and the protective layer is positioned on the surface of the pre-lithiated layer; the protective layer comprises the following components in percentage by mass: 85-98% of main component, 0.5-10% of binder and 0.1-5% of conductive agent; the main component is a negative electrode active material and/or an inert material.
Optionally, the negative electrode active material is graphite and/or lithium titanate, and the inert material is ceramic material and/or oxide; the binder is polyvinylidene fluoride, and the conductive agent is selected from one or a combination of more of conductive carbon black, acetylene black, graphene and carbon nanotubes; preferably, the ceramic material is selected from the group consisting of silicate ceramic, alumina ceramic, silicon nitride ceramic and silicon carbide ceramic, and the oxide is selected from the group consisting of aluminum-based, titanium-based, manganese-based and magnesium-based oxides.
Optionally, the protective layer further comprises a dispersant in an amount of 0.05 to 5% by mass.
Optionally, the thickness ratio of the protective layer in the pre-lithiated composite negative electrode plate is (0.5-10)%.
In a second aspect, the present invention relates to a method for preparing the prelithiated composite negative electrode plate of the first aspect, which comprises the following steps: (1) Dry-mixing the main body component, the binder and the conductive agent to obtain a first intermediate material; (2) The first intermediate material and a first part of solvent are subjected to first kneading, and then are subjected to second kneading and stirring with a second part of solvent, so that a second intermediate material is obtained; (3) And coating the second intermediate material on the surface of a pre-lithiation layer of the pre-lithiation negative electrode plate, and then drying and rolling to form a protective layer on the surface of the pre-lithiation layer so as to obtain the pre-lithiation composite negative electrode plate.
Optionally, the dry-mixed material in the step (1) further comprises a dispersing agent; the dry-mixing in the step (1) is carried out for 15-180min, and the dry-mixing is carried out at the humidity dew point of-30 ℃.
Optionally, in step (2): the first part of solvent and the second part of solvent are respectively N-methyl pyrrolidone; the solid content of the second intermediate material is 20-50%; the mass ratio of the first part solvent in the total amount of the first part solvent and the second part solvent is 30-50%.
Alternatively, in the step (2), the kneading time of the first kneading and the second kneading are each independently 10 to 120 minutes, and the stirring time is 60 to 360 minutes; step (2) is carried out under vacuum degree of-90 Kpa.
Optionally, the pre-lithiated negative electrode sheet in step (3) is prepared by: (S1) coating a negative electrode active slurry on a surface of a negative electrode current collector, and then drying and rolling to form a membrane layer on the surface of the negative electrode current collector; (S2) coating lithium powder on the surface of the membrane layer in the form of slurry, or rolling and loading a lithium belt on a PET film to form a lithium film with the thickness of 2-10um, and then pressing and coating the lithium film on the surface of the membrane layer through a film coating process; and forming a pre-lithiation layer on the surface of the membrane layer to obtain the pre-lithiation negative electrode plate.
In a third aspect, the present invention relates to a lithium ion battery, which comprises a positive electrode and a negative electrode, wherein the negative electrode is provided with the pre-lithiated composite negative electrode sheet according to the first aspect or the pre-lithiated composite negative electrode sheet manufactured by the manufacturing method according to the second aspect.
The beneficial effects are that:
according to the pre-lithiated composite negative electrode plate, the membrane layer, the pre-lithiation layer and the protective layer are sequentially arranged on the negative electrode current collector, contact reaction of metal lithium in the pre-lithiation layer with moisture and oxygen can be effectively avoided through the protective layer, stability and storage time in the storage process of the electrode plate are improved, dependence on a low-humidity environment is reduced, the problem of sticking of the metal lithium in the rolling process can be effectively avoided, and the first effect of an electric core prepared based on the pre-lithiated composite negative electrode plate is remarkably improved.
Detailed Description
The present application is further described in detail by way of examples below. The features and advantages of the present application will become more apparent from the description.
The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
In addition, the technical features described below in the different embodiments of the present application may be combined with each other as long as they do not collide with each other.
In a first aspect, the invention relates to a pre-lithiated composite negative electrode sheet, which comprises a pre-lithiated negative electrode sheet and a protective layer, wherein the pre-lithiated negative electrode sheet comprises a negative electrode current collector, a membrane layer and a pre-lithiated layer which are sequentially connected, and the protective layer is positioned on the surface of the pre-lithiated layer; the protective layer comprises the following components in percentage by mass: 85-98% of main component, 0.5-10% of binder and 0.1-5% of conductive agent; the main component is a negative electrode active material and/or an inert material.
In the pre-lithiated composite negative electrode sheet, the membrane layer, the pre-lithiation layer and the protective layer form a sandwich-like electrode sheet structure, and the sandwich electrode sheet structure can prevent metal lithium in the pre-lithiation layer from directly contacting with the outside, so that the problem of sticking to rollers in the rolling and production processes is effectively avoided; secondly, a protective layer is constructed between the pre-lithiation layer containing metal lithium and the steel roller or the pole piece parting knife, so that corrosion reaction of the metal lithium and the metal of the steel member in the equipment can be avoided, and the service life of the equipment is effectively prolonged; thirdly, the protection layer is a compact protection layer formed after rolling treatment, so that contact reaction of moisture and oxygen in air and lithium metal in the pre-lithiation layer can be effectively prevented, the risk of pole piece ignition is reduced, the safety stability and the storage time in the production process are improved, and meanwhile, the dependence on a low-humidity environment in the production process is reduced; fourth, through setting up the protective layer, can make the pre-lithiation layer exert the benefit lithium better, promote benefit lithium efficiency and benefit lithium effect, and then promote the electrochemical performance of pole piece.
In the protective layer, the mass ratio of the main component, the binder, and the conductive agent is a ratio based on the total mass of the protective layer. The pre-lithiation layer may be a lithium powder layer or a lithium film layer.
According to one embodiment of the pre-lithiated composite negative electrode sheet of the first aspect of the present invention, the negative electrode active material is graphite and/or lithium titanate, and the inert material is a ceramic material and/or oxide.
It should be noted that, the ceramic material and/or oxide is used as the main component to construct the protective layer, so that the protective effect can be well exerted, and the efficacy of the protective layer can be well exerted; as a preferred embodiment, graphite and/or lithium titanate are used as main components to construct a protective layer, so that not only can the isolation and protection function be well exerted, but also the electrochemical performance of the pole piece can be better improved.
According to one embodiment of the pre-lithiated composite negative electrode sheet of the first aspect of the present invention, the binder is polyvinylidene fluoride and the conductive agent is selected from one or more combinations of conductive carbon black, acetylene black, graphene and carbon nanotubes.
In the protective layer, the conductive agent can make the protective layer have good conductive performance, so that the pole piece has good electrochemical performance, and the adhesive can make the protective layer firmly bonded and connected to the surface of the pre-lithiated layer.
According to one embodiment of the pre-lithiated composite negative electrode sheet of the first aspect of the present invention, the ceramic material is selected from the group consisting of one or more of silicate ceramic, alumina ceramic, silicon nitride ceramic, and silicon carbide ceramic, and the oxide is selected from the group consisting of one or more of aluminum-, titanium-, manganese-, and magnesium-based oxides.
The protective layer constructed by taking the ceramic material or the oxide as a main component has good stability, can well play a role in protection, and enables the pre-lithiated layer to stably play a role in lithium supplementation.
According to one embodiment of the pre-lithiated composite negative electrode sheet of the first aspect of the present invention, the protective layer further comprises a dispersant in an amount of 0.05 to 5% by mass.
When the protective layer further contains a dispersant, the main component, the binder and the conductive agent together constitute the protective layer; the mass ratio of the dispersant refers to the mass ratio based on the total mass of the protective layer. The dispersing agent can be selected from one or a combination of more of polyethylene glycol, polyvinylpyrrolidone, N-methyl pyrrolidone, sodium carboxymethyl cellulose and the like.
According to one embodiment of the pre-lithiated composite negative electrode sheet of the first aspect of the present invention, the protective layer has a thickness ratio of (0.5-10)% in the pre-lithiated composite negative electrode sheet.
When the thickness ratio of the protective layer in the pre-lithiated composite negative electrode sheet is 5%, the thickness of the protective layer may be 5mm, and the thickness of the pre-lithiated negative electrode sheet formed by the negative electrode current collector, the membrane layer and the pre-lithiated layer may be 95mm. The protective layer can well exert the protective effect within the thickness range, and the cost is low.
In a second aspect, the present invention relates to a method for preparing the prelithiated composite negative electrode plate of the first aspect, which comprises the following steps: (1) Dry-mixing the main body component, the binder and the conductive agent to obtain a first intermediate material; (2) The first intermediate material and a first part of solvent are subjected to first kneading, and then are subjected to second kneading and stirring with a second part of solvent, so that a second intermediate material is obtained; (3) And coating the second intermediate material on the surface of a pre-lithiation layer of the pre-lithiation negative electrode plate, and then drying and rolling to form a protective layer on the surface of the pre-lithiation layer so as to obtain the pre-lithiation composite negative electrode plate.
In the preparation method of the invention, dry mixing is firstly carried out, the solvent is introduced twice for kneading, then the solid protective layer formed by closely contacting particles is obtained through coating, drying and rolling, the pre-lithiated composite negative electrode plate prepared by the preparation method of the second aspect of the invention can better protect the pre-lithiated layer, so that the metallic lithium in the protective layer can more effectively play a role of lithium supplementing, and further the electrode plate can obtain better electrochemical performance.
According to one embodiment of the preparation method according to the second aspect of the present invention, the dry-blended material in step (1) further comprises a dispersing agent; the dry-mixing in the step (1) is carried out for 15-180min, and the dry-mixing is carried out at the humidity dew point of-30 ℃.
In the step (1), the main component, the binder, the conductive agent and the dispersing agent are dry-mixed to obtain a first intermediate material, and the particles can be more uniformly distributed in the protective layer through the dry-mixing step of the step (1) to prevent agglomeration.
According to one embodiment of the preparation method according to the second aspect of the present invention, in step (2): the first portion of solvent and the second portion of solvent are each N-methylpyrrolidone.
According to one embodiment of the process according to the second aspect of the invention, the second intermediate material has a solids content of 20-50%.
According to an embodiment of the production method of the second aspect of the present invention, the mass ratio of the first partial solvent is 30 to 50% in the total amount of the first partial solvent and the second partial solvent.
The main component, the binder and the conductive agent in the dry mixing in the step (1) form a solid phase material, the total mass of the first part of solvent and the second part of solvent is the total mass of the liquid phase solvent, and the solid content can be the mass ratio of the mass of the solid phase material in the sum of the mass of the solid phase material and the total mass of the liquid phase solvent.
According to an embodiment of the production method of the second aspect of the present invention, in the step (2), the kneading time of the first kneading and the second kneading are each independently 10 to 120 minutes, and the stirring time is 60 to 360 minutes; step (2) is carried out under vacuum degree of-90 Kpa.
In the preparation method of the present invention, the conditions of each step are controlled to further obtain a more dense protective layer, so as to better exert the protective effect.
According to an embodiment of the preparation method according to the second aspect of the present invention, the pre-lithiated negative electrode sheet in step (3) is prepared by: (S1) coating a negative electrode active slurry on a surface of a negative electrode current collector, and then drying and rolling to form a membrane layer on the surface of the negative electrode current collector; (S2) coating lithium powder on the surface of the membrane layer in the form of slurry, or rolling and loading a lithium belt on a PET film to form a lithium film with the thickness of 2-10um, and then pressing and coating the lithium film on the surface of the membrane layer through a film coating process; and forming a pre-lithiation layer on the surface of the membrane layer to obtain the pre-lithiation negative electrode plate.
It should be noted that, the pre-lithiated negative electrode sheet in the present invention may be prepared by a conventional method in the art.
In a third aspect, the present invention relates to a lithium ion battery, which comprises a positive electrode and a negative electrode, wherein the negative electrode is provided with the pre-lithiated composite negative electrode sheet according to the first aspect, or the pre-lithiated composite negative electrode sheet manufactured by the manufacturing method according to the second aspect.
In the lithium ion battery, the pre-lithiated composite negative plate is provided with the protective layer, so that the performance of the lithium ion battery is obviously improved.
The protective layer described in the first aspect of the invention can be arranged in a pre-sodium-treated pole piece in a sodium ion battery, or in other words, the pre-lithiated composite negative pole piece or the preparation method of the invention can be applied to the sodium ion battery.
The present invention will be further described in detail by way of examples, which are not intended to limit the scope of the invention.
The reagents used in the examples below were all commercially available finished reagents except as specifically described. In the following examples, NMP represents N-methylpyrrolidone, CMC represents sodium carboxymethylcellulose, SBR represents styrene-butadiene rubber, PVDF represents polyvinylidene fluoride, EMC represents methylethyl carbonate, EC represents ethylene carbonate, PC represents propylene carbonate, and DMC represents dimethyl carbonate.
Preparation example of lithium powder pre-lithiated pole piece
(1) Preparation of anode membrane
According to graphite: conductive carbon black: CMC: the mass ratio of SBR is 95:2:1:2, mixing to obtain negative electrode active slurry; coating the negative electrode active slurry on the surface of a negative electrode current collector copper foil, and then drying and rolling to form a membrane layer on the surface of the negative electrode current collector;
(2) According to graphite: lithium powder: conductive carbon black: the mass ratio of PVDF is 80:10:8:
2, mixing to obtain lithium powder slurry; the thickness of the selected anode membrane film is 100-140um, the compaction is 1.5-1.6, then lithium powder slurry is uniformly coated on the membrane layer of the anode membrane, the thickness of the lithium powder membrane is controlled to be 10-30um, and the compaction is 1.5-1.6, so as to obtain the lithium powder pre-lithiated pole piece.
Preparation example of lithium strip rolled pre-lithiated pole piece
(1) Preparation of anode membrane
According to graphite: conductive carbon: CMC: the mass ratio of SBR is 95:2:1:2, mixing to obtain negative electrode active slurry; coating the negative electrode active slurry on the surface of a negative electrode current collector copper foil, and then drying and rolling to form a membrane layer on the surface of the negative electrode current collector;
(2) The thickness of the film coating of the anode film is 100-140um, the film coating is compacted by 1.5-1.6 um, and then a lithium film with the thickness of 4-8 um is pressed on the film layer of the anode film to obtain the lithium belt calendaring pre-lithiated pole piece.
Example 1:
1) The mass ratio of graphite, binder and conductive agent in the graphite-based protective layer is 96.5 percent: 2%:1.5 percent, loading a graphite-based protective layer on the lithium powder pre-lithiated pole piece prepared in the preparation example;
2) At the humidity dew point of minus 30 ℃, firstly, dry-mixing polyvinylidene fluoride (PVDF) serving as a binder, graphite and conductive carbon black serving as a conductive agent for 15min according to the proportion, adding NMP solvent accounting for 30% of the solid content after dry-mixing, then adding NMP solvent accounting for 40% of the total solvent for 60min, adding NMP solvent accounting for 60min of the total solvent after the first step of kneading, controlling vacuum degree to minus 90KPa, slowly stirring for 10min after the second step of kneading, quickly stirring for about 100min, controlling vacuum degree to minus 90KPa, measuring viscosity, fineness and observing bubbles after stirring, obtaining graphite slurry after the viscosity is 600-1200 Pa.s and fineness is less than 50um, and transferring the shipment flow to a coating process. The graphite slurry was then coated onto a lithium powder pre-lithiated pole piece (onto the pre-lithiated layer). Oven drying at 120deg.C or below. Drying the pole piece, transferring the pole piece to a rolling procedure, and rolling the pole piece until the compaction density is 1.5g/cm 3 The protective layer occupies 5% of the total thickness of the pre-lithiated composite negative electrode plate, and the pre-lithiated composite negative electrode plate is obtained.
Example 2
A pre-lithiated composite negative electrode sheet was prepared as in example 1, except that: the lithium powder pre-lithiated pole piece coated with the graphite slurry of example 1 was replaced with the lithium tape rolled pre-lithiated pole piece prepared in the preparation example described above.
Comparative example 1
The lithium powder pre-lithiated pole piece prepared in the preparation example is directly used as a negative pole piece.
Comparative example 2
The lithium strip prepared in the preparation example is directly used as a negative electrode plate for calendaring the pre-lithiated electrode plate.
Test examples
The pole pieces prepared in the above example 1, example 2, comparative example 1 and comparative example 2 were left to stand at ambient 25 ℃ and 2% rh humidity for 0h, 4h, 8h, 24h and 48h, respectively, and then the pole pieces were fabricated into cells according to the conventional methods in the art, respectively; when the battery cell is assembled, the diaphragm is a PE diaphragm with 9um, and the electrolyte is LiPF 6 The lithium salt is dissolved in an EMC/EC/PC/DMC solvent system, the positive electrode plate is a lithium iron phosphate plate, the battery is assembled into a winding mode of a negative electrode, a diaphragm and a positive electrode to be manufactured into a winding core, then the winding core is packaged in an aluminum plastic bag, and then electrolyte is injected to obtain the soft package battery core of 2Ah through infiltration, formation and capacity division. The first effect of the battery cell is calculated through formation and capacity division data, and the obtained first effect data result is shown in table 1 in detail.
TABLE 1
The first effect data of the pole piece prepared by the embodiment can be obviously improved, and the pole piece of the embodiment can obviously improve the stability of the lithium supplementing pole piece through the protective layer, so that the lithium supplementing efficiency and the lithium supplementing effect are improved, and the first effect of the pole piece at 24h and 48h is obviously improved compared with 91-92%.
In addition, experiments show that after the prepared pre-lithiated composite negative electrode sheet is assembled into a battery cell by taking ceramic materials such as lithium titanate, silicate ceramic, aluminum oxide ceramic, silicon nitride ceramic and the like or oxides such as aluminum oxide, titanium oxide and the like as main components in the protective layer and forming the protective layer together with a binder and a conductive agent, the first effect of the battery cell calculated by the chemical composition data can be obviously improved compared with that of a battery cell obtained by a comparative example electrode sheet without the protective layer.
In the description of the present application, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc. are based on the directions or positional relationships in the working state of the present application, are merely for convenience of description and simplification of description, and do not indicate or imply that the apparatus or element to be referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application.
In the description of the present application, it should be noted that the terms "mounted," "connected," and "connected" are to be construed broadly, unless explicitly specified and limited otherwise. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context.
The present application has been described in connection with the preferred embodiments, but these embodiments are merely exemplary and serve only as illustrations. On the basis of this, many alternatives and improvements can be made to the present application, which fall within the scope of protection of the present application.
Claims (10)
1. The pre-lithiated composite negative electrode plate is characterized by comprising a pre-lithiated negative electrode plate and a protective layer, wherein the pre-lithiated negative electrode plate comprises a negative electrode current collector, a membrane layer and a pre-lithiation layer which are sequentially connected, and the protective layer is positioned on the surface of the pre-lithiation layer; the protective layer comprises the following components in percentage by mass:
85-98% of main component, 0.5-10% of binder and 0.1-5% of conductive agent;
the main component is a negative electrode active material and/or an inert material.
2. The pre-lithiated composite negative electrode sheet of claim 1, wherein the negative electrode active material is graphite and/or lithium titanate, and the inert material is a ceramic material and/or oxide;
the binder is polyvinylidene fluoride, and the conductive agent is selected from one or a combination of more of conductive carbon black, acetylene black, graphene and carbon nanotubes;
preferably, the ceramic material is selected from the group consisting of silicate ceramic, alumina ceramic, silicon nitride ceramic and silicon carbide ceramic, and the oxide is selected from the group consisting of aluminum-based, titanium-based, manganese-based and magnesium-based oxides.
3. The prelithiation composite negative electrode sheet according to claim 1 or 2, wherein the protective layer further comprises a dispersant in an amount of 0.05 to 5% by mass.
4. The pre-lithiated composite negative electrode sheet of claim 1 or 2, wherein the protective layer has a thickness ratio of (0.5-10)% in the pre-lithiated composite negative electrode sheet.
5. A method for preparing the prelithiation composite negative plate according to any one of claims 1 to 4, which is characterized by comprising the following steps:
(1) Dry-mixing the main body component, the binder and the conductive agent to obtain a first intermediate material;
(2) The first intermediate material and a first part of solvent are subjected to first kneading, and then are subjected to second kneading and stirring with a second part of solvent, so that a second intermediate material is obtained;
(3) And coating the second intermediate material on the surface of a pre-lithiation layer of the pre-lithiation negative electrode plate, and then drying and rolling to form a protective layer on the surface of the pre-lithiation layer so as to obtain the pre-lithiation composite negative electrode plate.
6. The process of claim 5 wherein the dry blended material of step (1) further comprises a dispersant;
the dry-mixing in the step (1) is carried out for 15-180min, and the dry-mixing is carried out at the humidity dew point of-30 ℃.
7. The method according to claim 5, wherein in the step (2):
the first part of solvent and the second part of solvent are respectively N-methyl pyrrolidone;
the solid content of the second intermediate material is 20-50%;
the mass ratio of the first part solvent in the total amount of the first part solvent and the second part solvent is 30-50%.
8. The method according to claim 5, wherein in the step (2), the kneading time of the first kneading and the second kneading are each independently 10 to 120 minutes, and the stirring time is 60 to 360 minutes;
step (2) is carried out under vacuum degree of-90 Kpa.
9. The method according to claim 5, wherein the pre-lithiated negative electrode sheet in step (3) is prepared by:
(S1) coating a negative electrode active slurry on a surface of a negative electrode current collector, and then drying and rolling to form a membrane layer on the surface of the negative electrode current collector;
(S2) coating lithium powder on the surface of the membrane layer in the form of slurry, or rolling and loading a lithium belt on a PET film to form a lithium film with the thickness of 2-10um, and then pressing and coating the lithium film on the surface of the membrane layer through a film coating process; and forming a pre-lithiation layer on the surface of the membrane layer to obtain the pre-lithiation negative electrode plate.
10. A lithium ion battery comprising a positive electrode and a negative electrode, characterized in that the negative electrode is provided with the pre-lithiated composite negative electrode sheet of any one of claims 1 to 4, or with the pre-lithiated composite negative electrode sheet produced by the production method of any one of claims 5 to 9.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116230944A (en) * | 2023-05-05 | 2023-06-06 | 四川新能源汽车创新中心有限公司 | Thermal-insulation pre-lithiation functional layer and lithium ion battery thereof |
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2023
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116230944A (en) * | 2023-05-05 | 2023-06-06 | 四川新能源汽车创新中心有限公司 | Thermal-insulation pre-lithiation functional layer and lithium ion battery thereof |
| CN116230944B (en) * | 2023-05-05 | 2023-09-01 | 四川新能源汽车创新中心有限公司 | Thermal-insulation pre-lithiation functional layer and lithium ion battery thereof |
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