CN114430023A - Composite negative plate, preparation method thereof and lithium metal secondary battery - Google Patents

Composite negative plate, preparation method thereof and lithium metal secondary battery Download PDF

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CN114430023A
CN114430023A CN202210069391.7A CN202210069391A CN114430023A CN 114430023 A CN114430023 A CN 114430023A CN 202210069391 A CN202210069391 A CN 202210069391A CN 114430023 A CN114430023 A CN 114430023A
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lithium
current collector
graphite
negative
negative electrode
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李玉冰
徐雄文
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Hunan Lifang New Energy Science and Technology Co Ltd
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Priority to PCT/CN2022/108258 priority patent/WO2023138018A1/en
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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
    • H01M4/133—Electrodes based on 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
    • 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
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of electrodes based on 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
    • 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

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  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention belongs to the technical field of lithium metal secondary batteries, and particularly relates to a composite negative plate, a preparation method thereof and a lithium metal secondary battery. According to the composite negative plate, the coating layer is arranged on the surface of the negative current collector, the graphite plate layers which are perpendicular to the current collector and are arranged in parallel are arranged in the coating layer, dead lithium and lithium dendrites generated by the graphite plate layers can be partially accommodated, and safety accidents caused by internal short circuit due to the fact that the dendrites pierce through the diaphragm can be avoided. Meanwhile, part of lithium dendrites will be deposited on the bottom of the graphite coating, which is buried by the 'dead lithium' or active lithium, etc. generated later, reducing the contact between the dendrites and the electrolyte, reducing the consumption of the electrolyte and increasing the cycle life of the battery.

Description

Composite negative plate, preparation method thereof and lithium metal secondary battery
Technical Field
The invention belongs to the technical field of lithium metal secondary batteries, and particularly relates to a composite negative plate, a preparation method of the composite negative plate and a lithium metal secondary battery.
Background
Among all the materials of lithium secondary batteries, metallic lithium, which has an ultra-high theoretical specific capacity (3860mAh/g), and an extremely low potential (-3.04V, relative to a standard hydrogen electrode), is considered as an ideal negative electrode material of the next generation of high energy density lithium batteries, and is called "holy cup" in the electrode. Among them, the high nickel ternary system material matched with the lithium metal cathode is considered to be a battery system which can break through the energy density of 500Wh/Kg to the greatest extent. Secondary batteries using lithium metal as a negative electrode, such as lithium sulfur batteries and lithium oxygen batteries, are considered to be a promising next-generation high specific energy battery. However, in the battery cycle process, due to internal or external factors such as uneven surface of the negative electrode, uneven current distribution and thermal distribution, deposition and stripping of lithium ions on the surface of the negative electrode are often uneven, lithium dendrites are easily generated by the uneven deposition and stripping, a diaphragm is easily pierced by a large number of lithium dendrites, internal short circuit is caused by direct contact of the positive electrode and the negative electrode, and safety accidents are possibly caused. Meanwhile, the existence of the lithium dendrite can also lead the consumption rate of the electrolyte and the reversible lithium source to be greatly accelerated, and can also be converted into 'dead lithium' which loses electrochemical activity and covers the surface of the negative electrode, so that the transmission of lithium ions is blocked, and the cycle life of the battery is shortened.
In order to deal with the above-mentioned problems of lithium dendrites and 'dead lithium', researchers developed novel electrolyte additives by adjusting the electrolyte formulation, constructed 3D host structures or covered a layer of artificial SEI protective layer on the lithium metal surface. Among them, the adjustment of the electrolyte formulation and the development of a novel electrolyte additive are often costly, so that the selling price of products using the electrolyte additive is increased accordingly. The composite cathode with the 3D structure is large in specific surface area, low in first coulomb efficiency of battery circulation and large in side reaction degree. The SEI film is also called a solid-liquid interfacial film, which is a film on the surface of lithium metal to isolate the electrolyte from the continuous reaction with lithium, and has the properties of good ion conductor and electron insulator. The lithium metal negative electrode is not bound by a main body structure, the volume expansion of the lithium metal negative electrode is nearly infinite in the circulation process, and the large volume expansion often causes the fracture of an SEI film in the battery circulation process, so that the artificial SEI film can prolong the service life of the battery to a certain extent, but still has the problem of repeated fracture repair of the SEI film along with the circulation, and the growth of lithium dendrites in the later period of the circulation is uncontrollable.
In view of the above, it is an urgent issue in the industry to find a suitable method for reducing the consumption of the electrolyte and the reversible active lithium to improve the cycle life and the safety performance of the lithium metal battery.
Disclosure of Invention
One of the objects of the present invention is: aiming at the defects of the prior art, the composite negative plate is provided, which can reduce the consumption of electrolyte and reversible active lithium, and improve the cycle life and the safety performance of the battery.
In order to achieve the purpose, the invention adopts the following technical scheme:
the utility model provides a composite negative plate, includes that the negative pole collects the fluid and coats in the coating of the at least one surface of negative pole collection fluid, be provided with a plurality of graphite flakes in the coating, at least some graphite flakes set up with the negative pole collection fluid is perpendicular, and separate each other between this part graphite flake and set up.
The SEI film grown in situ in the battery cycle process is generally poor in mechanical property and flexibility, and is easy to crack due to factors such as volume expansion in the long cycle process, so that dendritic crystal growth is not controlled, the cycle life is short, and the safety performance is poor. According to the negative plate, the coating layer is arranged on the surface of the negative current collector, the graphite sheets which are vertically arranged and separated from each other are arranged in the coating layer, and the graphite sheets which are vertically arranged and arranged in parallel with each other of the current collector can partially contain dead lithium and lithium dendrites generated by the current collector in the subsequent circulation process of the battery, so that safety accidents caused by internal short circuit due to the fact that the dendrites penetrate through a diaphragm are avoided to a certain extent. Meanwhile, because part of lithium dendrites generated in the circulation process can be deposited at the bottom of the graphite coating and are buried by 'dead lithium' or active lithium and the like generated later, the contact between the dendrites and the electrolyte is reduced to a certain extent, the consumption of the electrolyte is reduced, and the effect of prolonging the cycle life of the battery is achieved.
Preferably, the negative current collector is any one of a copper foil, a nickel foil, a stainless steel sheet, a metal lithium foil and a metal lithium-based alloy foil. The negative electrode current collector may be a lithium metal current collector or a non-lithium metal alloy-based current collector.
When a non-lithium based current collector or a non-lithium metal alloy based current collector is selected, the negative electrode is initially free of lithium, and the ratio of the theoretical capacity acceptable by the magnetic perpendicular graphite sheet coated thereon to the theoretical capacity that the positive electrode material can exert in the voltage region is much less than 1, i.e., the N/P ratio is much less than 1. At this time, when the battery is charged, lithium ions released from the positive electrode are partially intercalated into the graphite negative electrode, and LiC is used6And the like. Because the theoretical quantity of lithium ions accepted by the negative electrode is far less than the theoretical quantity of lithium ions released by the positive electrode, the other part of the excessive lithium ions which are not embedded by the graphite material on the negative electrode side are partially deposited between the gaps of the graphite sheets of the vertical current collectors which are parallel to each other at the negative electrode until the gaps are filled and overflowed, and the excessive lithium is further deposited on the top surface of the graphite sheets after the overflow to form a lithium metal layer with a certain thickness. Due to the partial irreversibility of lithium ion extraction, some of the lithium extracted from the positive electrode side cannot be returned to the positive electrode again during discharge, and remains on top of the graphite layer or in the graphite sheet gap. During the discharge phase, the lithium deposited on top of the graphite is preferentially exfoliated before the lithium deposited in the interstices of the graphite platelets is exfoliated. In the process, even if the dendritic crystal or the 'dead lithium' is generated due to uneven stripping, the 'dead lithium' and the lithium dendritic crystal fall into the graphite gap and are buried by the subsequent reversible active lithium because the opening of the graphite sheet layer is upward and has a certain depth, so that the effect of obstructing the lithium ion transmission is reduced, the consumption of electrolyte is reduced, and the cycle life and the safety performance of the battery are improved.
When the used current collector is a lithium-based current collector, the theoretical capacity ratio of the negative side to the positive side is more than 1, namely the ratio of N/P is more than 1, because the negative side can provide a lithium source. At this time, compared with the uncoated lithium foil cathode, the coated graphite sheet layer described in the patent can be understood as a cage structure, and the function of the coated graphite sheet layer is to completely trap lithium coming out from the cathode side to form lithium dendrites and 'dead lithium' in the subsequent cycle process, thereby achieving the purposes of reducing the electrolyte consumption, and improving the cycle life and the safety performance. Meanwhile, it should be noted that when the current collector used in the negative electrode is a lithium-based material, although only the theoretical capacity of the coated graphite sheet layer is calculated to be smaller than 1. However, since the negative electrode is actually a composite negative electrode of graphite and lithium, which itself provides a lithium source, the ratio of the total theoretical capacity of the negative electrode side to the theoretical capacity of the positive electrode is much greater than 1.
Preferably, the coating slurry further comprises a thickening agent and a binder, and the graphite sheet, the thickening agent and the binder are mixed in a weight ratio of 94-98: 1-3: 1-3. And arranging a certain amount of graphite flakes, thickening agent and binder to make the prepared coating slurry have a certain viscosity, so that the coating and fixing of the coating slurry are facilitated.
Preferably, the binder comprises one or more of polytetrafluoroethylene, styrene butadiene rubber, polyacrylate, polyimide, sodium polyacrylate, chitosan, polyvinylidene fluoride and polyvinylidene fluoride.
Preferably, all of the graphite sheets are disposed perpendicular to the negative electrode current collector. All the graphite sheets are perpendicular to the negative current collector, so that the electrochemical performance of the composite negative plate can be improved.
Wherein the thickening agent is sodium carboxymethyl cellulose.
The second purpose of the invention is: aiming at the defects of the prior art, the preparation method of the composite negative plate is provided, is simple to operate and can be used for batch production.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of a composite negative plate comprises the following steps:
step S1, mixing the graphite flake modified by the magnetic substance with the binder and the thickening agent, adding the solvent, and stirring to prepare coating slurry;
and S2, selecting a negative current collector, arranging a magnetic field emission device, coating the coating slurry on at least one surface of the negative current collector, and drying the coating slurry in the magnetic field emission device to form a coating layer to obtain the composite negative plate, wherein the magnetic field emission device is used for vertically arranging the graphite sheet modified by the magnetic substances in the coating slurry and the negative current collector.
Micron-sized platelets suspended in a fluid and decorated with magnetic nanoparticles have two different states of orientation under a rotating magnetic field. Which is highly dependent on the magnetic field rotation frequency and the rheological properties of the fluid. When the rotation frequency of the magnetic field is low enough, the magnetic substance modified particles are controlled by magnetic torque, and the magnetic torque synchronously rotates on the surface of the current collector along the direction of the rotation field. When the rotation frequency is sufficiently high, the determination step of the motion state of the magnetic substance is changed to fluid viscosity, and at this time, the magnetic substance is aligned in parallel with the plane of the rotating magnetic field.
Preferably, the coating slurry further includes a solvent, and the solvent is an aqueous solvent or an oil-based solvent. When the negative electrode current collector uses copper foil or nickel foil, the negative electrode slurry may use an aqueous solvent including, but not limited to, water, methanol, and ethanol, and when the negative electrode current collector is a current collector such as lithium metal or lithium metal-based alloy foil, which is susceptible to dangerous accidents such as combustion and explosion under normal circumstances, the negative electrode slurry may use an oil solvent including, but not limited to, N-methylpyrrolidone (NMP), N-Dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). When the oil solvent is used, the coating of the prize-winning metal and the subsequent battery assembly process are carried out in a drying room with the dew point temperature of less than minus 36 ℃. When the slurry is prepared by using an oil solvent, the water content of the solvent is ensured to be less than 20ppm before the preparation.
The third purpose of the invention is: aiming at the defects of the prior art, the lithium metal secondary battery is provided, and has good electrochemical performance and safety performance.
In order to achieve the purpose, the invention adopts the following technical scheme:
the utility model provides a lithium metal secondary battery, includes positive plate, barrier film, negative pole piece, electrolyte and casing, the barrier film is separated positive plate with the negative pole piece, the casing is used for installing positive plate, barrier film, negative pole piece and electrolyte, the negative pole piece is foretell compound negative pole piece.
The battery structure of the lithium metal secondary battery may be a laminate type, a winding type, or a hybrid type.
Preferably, the positive plate comprises a positive current collector and a positive active material layer coated on at least one surface of the positive current collector, and the positive active material layer comprises one or a mixture of more of lithium cobaltate, lithium nickel manganese oxide, lithium nickel manganese cobaltate, lithium nickel cobalt aluminate, lithium iron phosphate, lithium manganese oxide, a lithium-rich manganese base and lithium iron manganese phosphate.
Preferably, the separation film is any one of a polyethylene film, a polypropylene film, a polyethylene-polypropylene composite film, a polyimide film and a ceramic film.
Compared with the prior art, the invention has the beneficial effects that: according to the negative plate, the coating layer is arranged on the surface of the negative current collector, the graphite sheets which are vertically arranged and separated from each other are arranged in the coating layer, and the graphite sheets which are vertically arranged and arranged in parallel with each other of the current collector can partially contain dead lithium and lithium dendrites generated by the current collector in the subsequent circulation process of the battery, so that safety accidents caused by internal short circuit due to the fact that the dendrites penetrate through a diaphragm are avoided to a certain extent. Meanwhile, because part of lithium dendrites generated in the circulation process can be deposited at the bottom of the graphite coating and are buried by 'dead lithium' or active lithium and the like generated later, the contact between the dendrites and the electrolyte is reduced to a certain extent, the consumption of the electrolyte is reduced, and the effect of prolonging the cycle life of the battery is achieved.
Drawings
Fig. 1 is a schematic structural view of a prior art negative electrode sheet.
Fig. 2 is a schematic structural view of the negative electrode sheet of the present invention.
FIG. 3 is a graph comparing capacity retention rate curves of example 1 of the present invention and comparative example 1.
Wherein: 1. a negative current collector; 2. a graphite sheet; 3. and (4) lithium ions.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and the accompanying drawings, but the embodiments of the invention are not limited thereto.
Example 1
A preparation method of a composite negative plate comprises the following steps:
step S1, mixing the graphite flake 2 modified by the magnetic substance with a binder and a thickening agent, adding a solvent, and stirring to prepare coating slurry;
step S2, selecting a negative current collector 1, arranging a magnetic field emission device, coating the coating slurry on at least one surface of the negative current collector 1, and drying the coating slurry in the magnetic field emission device to form a coating layer, so as to obtain the composite negative plate, wherein the magnetic field emission device is used for vertically arranging the graphite sheet 2 modified by the magnetic substances in the coating slurry and the negative current collector 1. The composite negative plate that prepares is shown in fig. 2, the level is placed for negative current collector 1, set up for graphite flake 2 with negative current collector 1 is perpendicular and the interval, a plurality of graphite flakes 2 separate each other and set up, form an upwardly open-ended accommodation space with negative current collector 1, can hold lithium ion 3, when 'dying lithium' or lithium dendrite appear, the accommodation space of formation can install 'dying lithium' or lithium dendrite, thereby avoid the lithium dendrite that generates to pierce through the diaphragm and lead to interior short circuit, initiation battery incident. Meanwhile, the contact between the electrolyte and the lithium dendrite can be reduced to a certain extent, and the consumption of the electrolyte is reduced, so that the effects of improving the safety performance and prolonging the cycle life of the battery are achieved.
Wherein the weight part ratio of the graphite sheet 2, the thickening agent and the binding agent in the coating layer is 95:2.5: 2.5.
Wherein, the binder is polytetrafluoroethylene, and the thickening agent is sodium carboxymethylcellulose.
The negative electrode current collector 1 is a metal lithium foil, the solvent is an oil solvent, and the oil solvent is N-methylpyrrolidone.
Wherein, the isolating film is a polyethylene film.
Example 2
The difference from example 1 is that: the weight part ratio of the graphite sheet 2, the thickening agent and the binder in the coating layer is 98:2: 2.
The rest is the same as embodiment 1, and the description is omitted here.
Example 3
The difference from example 1 is that: the weight part ratio of the graphite sheet 2, the thickening agent and the binder in the coating layer is 94:2: 2.
The rest is the same as embodiment 1, and the description is omitted here.
Example 4
The difference from example 1 is that: the weight part ratio of the graphite sheet 2, the thickening agent and the binder in the coating layer is 95:1: 1.
The rest is the same as embodiment 1, and the description is omitted here.
Example 5
The difference from example 1 is that: the weight part ratio of the graphite sheet 2, the thickening agent and the binder in the coating layer is 95:1: 3.
The rest is the same as embodiment 1, and the description is omitted here.
Example 6
The difference from example 1 is that: the negative current collector 1 is a copper foil, the solvent is an aqueous solvent, and the solvent is water.
The rest is the same as embodiment 1, and the description is omitted here.
Comparative example 1
The difference from example 1 is that: the preparation method of the negative plate comprises the following steps:
step S1, mixing the graphite flake 2 modified by the magnetic substance with a binder and a thickening agent, adding a solvent, and stirring to prepare coating slurry;
step S2, selecting a negative current collector 1, coating the coating slurry on at least one surface of the negative current collector 1, and drying to form a coating layer, thereby obtaining a negative electrode sheet, as shown in fig. 1.
The rest is the same as embodiment 1, and the description is omitted here.
And (3) performance testing: the secondary batteries prepared in examples 1 to 6 and comparative example 1 were subjected to a capacity retention rate performance test after 120 charge/discharge cycles, and the test results are reported in table 1.
TABLE 1
Figure BDA0003481448440000071
Figure BDA0003481448440000081
As can be seen from fig. 3 and table 1, the secondary battery of the present invention still maintains a capacity retention rate of 84% to 88% after 120 charges and discharges and has good electrochemical properties, compared to the secondary battery of comparative example 1. Also, as can be seen from comparison of examples 1 to 5, when the graphite sheet 2, the thickener, and the binder were disposed in the coating layer at a weight ratio of 95:2.5:2.5, the prepared secondary battery had a better capacity retention rate. As can be seen from comparison of examples 1 to 5 and 6, when the negative electrode current collector 1 is a metallic lithium foil and the solvent is an oil-based solvent, the secondary battery prepared using the copper foil as the negative electrode current collector 1 has better electrochemical properties than the secondary battery prepared using an aqueous solvent.
The examples 1 to 3 and the comparative example 1 were subjected to discharge capacity and discharge rate tests at different rates, and the test results are reported in table 2.
TABLE 2
Figure BDA0003481448440000082
Figure BDA0003481448440000091
As can be seen from the above table 2, comparative example 1 has a capacity of about 40mAh at a rate of 3C, and the capacity retention rate is only 16.89% of the initial; the discharge capacity at 3C rate of examples 1-3 of the present invention is 75.7mAh/g on average, which is about 36.63% of the initial value, and the capacity retention rate, discharge rate and discharge voltage of the battery of the present invention are all higher than those of comparative example 1, and as can be seen from fig. 3, the battery of the present invention has better electrochemical performance.
Variations and modifications to the above-described embodiments may also occur to those skilled in the art, which fall within the scope of the invention as disclosed and taught herein. Therefore, the present invention is not limited to the above-mentioned embodiments, and any obvious improvement, replacement or modification made by those skilled in the art based on the present invention is within the protection scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (10)

1. The composite negative plate is characterized by comprising a negative current collector and a coating coated on at least one surface of the negative current collector, wherein a plurality of graphite flakes are arranged in the coating, at least one part of graphite flakes is perpendicular to the negative current collector, and the part of graphite flakes are separated from each other.
2. The composite negative electrode sheet according to claim 1, wherein the negative electrode current collector is any one of a copper foil, a nickel foil, a stainless steel sheet, a metallic lithium foil, and a metallic lithium-based alloy foil.
3. The composite negative electrode sheet according to claim 1 or 2, wherein the coating layer further comprises a thickening agent and a binder, and the weight ratio of the graphite sheet to the thickening agent to the binder is 94-98: 1-3: 1-3.
4. The composite negative electrode sheet according to claim 3, wherein the binder comprises one or more of polytetrafluoroethylene, styrene-butadiene rubber, polyacrylate, polyimide, sodium polyacrylate, chitosan, polyvinylidene fluoride and polyvinylidene fluoride.
5. The composite negative electrode sheet according to claim 1, wherein all of the graphite sheets are disposed perpendicular to the negative electrode current collector.
6. The method for preparing a composite negative electrode sheet according to any one of claims 1 to 5, comprising the steps of:
step S1, mixing the graphite flake modified by the magnetic substance with the binder and the thickening agent, adding the solvent, and stirring to prepare coating slurry;
and S2, selecting a negative current collector, arranging a magnetic field emission device, coating the coating slurry on at least one surface of the negative current collector, and drying the coating slurry in the magnetic field emission device to form a coating layer to obtain the composite negative plate, wherein the magnetic field emission device is used for vertically arranging the graphite sheet modified by the magnetic substances in the coating slurry and the negative current collector.
7. The method for preparing a composite negative electrode sheet according to claim 6, wherein the coating slurry further comprises a solvent, and the solvent is an aqueous solvent or an oil solvent.
8. A lithium metal secondary battery, characterized in that, includes positive plate, barrier film, negative plate, electrolyte and casing, the said barrier film separates the said positive plate and the said negative plate, the said casing is used for installing positive plate, barrier film, negative plate and electrolyte, the said negative plate is the composite negative plate of any claim 1-5.
9. The lithium metal secondary battery of claim 8, wherein the positive plate comprises a positive current collector and a positive active material layer coated on at least one surface of the positive current collector, and the positive active material layer comprises one or more of lithium cobaltate, lithium nickel manganese oxide, lithium nickel manganese cobalt oxide, lithium nickel cobalt aluminate, lithium iron phosphate, lithium manganese oxide, lithium rich manganese base or lithium iron manganese phosphate.
10. The lithium metal secondary battery according to claim 8, wherein the separator is any one of a polyethylene film, a polypropylene film, a polyethylene-polypropylene composite film, a polyimide film, and a ceramic film.
CN202210069391.7A 2022-01-21 2022-01-21 Composite negative plate, preparation method thereof and lithium metal secondary battery Pending CN114430023A (en)

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WO2023138018A1 (en) * 2022-01-21 2023-07-27 湖南立方新能源科技有限责任公司 Composite negative electrode plate and preparation method therefor, and lithium metal secondary battery

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