CN112038575B

CN112038575B - Lithium belt and preparation method and application thereof

Info

Publication number: CN112038575B
Application number: CN202010901357.2A
Authority: CN
Inventors: 马忠龙; 赵晓宇; 秦士林; 郑晓醒
Original assignee: Svolt Energy Technology Co Ltd
Current assignee: Svolt Energy Technology Co Ltd
Priority date: 2020-08-31
Filing date: 2020-08-31
Publication date: 2021-10-22
Anticipated expiration: 2040-08-31
Also published as: CN112038575A

Abstract

The invention provides a lithium belt and a preparation method and application thereof; the lithium belt comprises a polymer with a network structure and lithium metal particles bonded on the surface of the polymer, has higher mechanical strength than a common lithium belt, is high in degree of attachment with an electrode pole piece, has good lithium supplementing efficiency, and can effectively improve the first effect of a battery; the preparation method comprises the steps of premixing the fiberizable polymer and the lithium metal particles, drawing the fiberizable polymer into fibers under the action of shearing force, and carrying out cold pressing treatment or hot pressing treatment under the protection of inert gas to a preset thickness to obtain the lithium belt.

Description

Lithium belt and preparation method and application thereof

Technical Field

The invention belongs to the field of battery materials, and relates to a lithium belt and a preparation method and application thereof.

Background

With the rapid development of new energy vehicles, the requirements on the energy density and the safety performance of the power battery for vehicles are continuously improved. It is expected that the energy density of the power battery will reach over 500Wh/kg by 2025. With the increasing energy density of power batteries, the gram capacity and the compaction density of the existing negative electrode materials reach limit values, so that the use of silicon carbon materials is a hot spot for a future period of time. Meanwhile, the problems of material pulverization and matching with related electrolyte and glue are always puzzled by related scientific research personnel due to low first charge-discharge efficiency, large expansion and long circulation of the silicon-carbon material, the development of a high-energy-density power battery is severely restricted, and the requirement of people on long-endurance new energy automobiles is influenced. The lithium supplement technology is a practical and effective means, has great application prospect in the aspects of improving the first effect of the battery cell, prolonging the cycle life and the like, and has particularly obvious effect on a battery cell system adopting a silicon-carbon cathode. The method is also suitable for a graphite system, and has a good improvement effect on the aspect of prolonging the cycle life of the battery cell;

according to the analysis of the existing published patent documents, the main lithium supplement technologies at present mainly take lithium powder or lithium foil for lithium supplement, electrochemical lithium supplement, lithium supplement additive for lithium supplement, and positive electrode lithium supplement as main research directions, wherein lithium supplement by lithium powder and lithium supplement by lithium foil are considered as two most commercially available lithium supplement modes. The Beijing Weilan new energy science and technology Limited CN107658496A discloses that the cycle life of a secondary battery can be remarkably prolonged by introducing an alkali metal belt; beijing Yijin New energy science and technology Limited CN109873122A discloses a preparation method of an ultrathin metal lithium complex, which forms a lithium thin layer by rapidly spreading molten metal lithium on the surface of a substrate, and is used as a safe lithium cathode for inhibiting lithium dendrite.

In the current lithium supplement technology capable of realizing industrialization, lithium powder and an ultrathin lithium belt are taken as main research trends, but the preparation process of the lithium powder is relatively complex and involves heating melting and post-treatment of lithium metal, and the requirements of later-stage lithium powder use on equipment and environment are relatively strict, so that the large-scale use of the lithium powder is limited; in the preparation process of the ultrathin lithium belt, the physical appearance of lithium metal is changed, complex chemical reaction is not involved, and most lithium metal can be completed at a lower temperature, so that the difficulty in production and manufacturing is greatly reduced compared with the preparation process of lithium powder.

However, most of the current lithium tapes use a metal film or a polymer film, which is inert to metal, as a support because lithium metal has poor strength and is very flexible, and when the thickness of lithium metal is reduced to a certain extent, it is difficult to maintain a complete continuous phase and is easily broken; the use difficulty of the lithium belt at the later stage is increased, the lithium belt is required to be peeled off from the support body firstly in the use process and then can be further used, the waste of the lithium belt is caused, and the cost is increased; in addition, most of the lithium belts on the market are dozens of microns to hundreds of microns, and the lithium belts are directly applied to most of battery core systems, so that the lithium supplement amount is excessive, and the electrode plates are inevitably subjected to lithium precipitation in the early-stage circulation process of the battery core, so that the short circuit of the battery is caused.

Therefore, it is still significant to develop a lithium ribbon having high mechanical strength and high capacity and a method for preparing the same.

Disclosure of Invention

The invention aims to provide a lithium belt and a preparation method and application thereof; the lithium belt comprises a polymer with a network structure and lithium metal particles bonded on the surface of the polymer, has higher mechanical strength than a common lithium belt, is high in degree of attachment with an electrode pole piece, is high in lithium supplementing efficiency, and can effectively improve the first-effect performance of a battery; the preparation method comprises the steps of premixing the fiberizable polymer and the lithium metal particles, drawing the fiberizable polymer into fibers under the action of shearing force, and then carrying out cold pressing treatment or hot pressing treatment under the protection of inert gas to a preset thickness to obtain the lithium belt.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a lithium ribbon comprising a polymer in a network structure and lithium metal particles bonded to the surface of the polymer.

The following problems exist in the lithium supplementing process of the common lithium belt: the fitting degree of the lithium belt and the electrode pole piece is poor, the lithium supplementing process is slow, higher pressure is needed to ensure the fitting of the lithium belt and the pole piece, and the pole piece is easy to deform seriously due to the higher pressure; compared with the common lithium belt, the lithium belt has higher mechanical strength, higher attaching degree with the electrode pole piece and small attaching pressure; and the capacity can be exerted to be higher, the effective capacity can reach 3450mAh/g, and the lithium supplement effect is better. The battery obtained by the method has higher first effect, and the first effect can reach more than 93.5 percent.

The polymer surface here includes the inner and outer pore surfaces of the polymer with a network structure.

Preferably, the thickness of the lithium ribbon is 1 to 500 μm, such as 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 5 μm, 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, or the like.

Preferably, the lithium tape is a self-supporting lithium tape.

Preferably, the lithium metal particles have a particle size of 100 μm or less, such as 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, or 90 μm, and the like.

Preferably, the polymer with the network structure is formed by drawing the fiberizable polymer under the action of shearing force to form fibers, and the fibers are mutually overlapped in the cold pressing treatment or hot pressing treatment process, and the high-speed shearing speed is more than or equal to 1000 rpm; for example, 3000rpm, 5000rpm, 10000rpm, 15000rpm, 20000rpm, 25000rpm, or the like; the polymer with the network structure obtained by combining the shearing action with cold pressing treatment or hot pressing treatment has better mechanical property, is convenient to process and use in later period, and is easier to accurately control the lithium content.

Preferably, the hot pressing process is carried out under the protection of inert gas.

Preferably, the cold pressing treatment is carried out at a temperature of 25 ℃ or less, such as 5 ℃, 10 ℃, 15 ℃ or 20 ℃ or the like.

Preferably, the temperature of the hot pressing treatment is less than or equal to 100 ℃, such as 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃ or 90 ℃, and the like, and preferably 50-90 ℃.

Preferably, the fiberizable polymer is a thermoplastic fiberizable polymer.

Preferably, the fiberizable polymer comprises at least one of Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), Polyimide (PI), Polyacrylonitrile (PAN), polypropylene (PP), Polyethylene (PE), Polystyrene (PS), and polyacrylic acid (PAA).

Preferably, the mass percentage of the polymer having a network structure in the lithium ribbon is 3 to 90%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, etc., preferably 5 to 15%, based on 100% of the mass of the lithium ribbon.

Preferably, the lithium metal particles are contained in the lithium ribbon in a mass percentage of 10 to 97%, for example, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, and preferably 85 to 95%, based on 100% by mass of the lithium ribbon.

In a second aspect, the present invention provides a method of preparing a lithium ribbon as described in the first aspect, the method comprising the steps of:

(1) premixing a fiberizable polymer with lithium metal particles, and then drawing the fiberizable polymer under the action of shear force to form fibers;

(2) performing cold pressing treatment on the product obtained in the step (1) to a preset thickness to obtain the lithium strip;

or under the protection of inert gas, carrying out hot pressing treatment on the product obtained in the step (1) to a preset thickness to obtain the lithium belt.

The method of the invention mixes the fiberizable polymer and the lithium metal particles after premixing under the action of shearing force, so that the fiberizable polymer and the lithium metal particles are fully and uniformly mixed. In the process, no solvent or liquid additive is used, but the two kinds of powder are fully and effectively mixed; this can avoid the introduction of excess species causing a reduction in the effective capacity of lithium metal; and the existence of the fiberizable polymer can fully bond the lithium metal powder; the subsequent powder which is fully mixed uniformly is rolled by external force, so that the lithium metal particles are extended to reach the required thickness of the lithium belt. Therefore, the proper proportion of the polymer to the lithium metal particles and the thickness of the finally formed self-supporting lithium belt can be adjusted according to different use scenes and use processes.

The invention adopts dry mixing, and the mixture of the fiberizable polymer and the lithium metal particle powder is sheared to prepare the dry powder with certain viscosity, wherein, in the shearing action process, the polymer is drawn and fiberized to bond the lithium metal particles and endow the powder with certain viscosity; and then, cold pressing or hot pressing is carried out to prepare a membrane, the dry powder is pressed into a membrane-shaped sheet with a certain thickness, in the pressing process, the wiredrawing and fiberizing polymers are mutually overlapped, extruded and moved, further fiberization is carried out, a network structure is formed, the bonding effect between the lithium metal particles and the polymers is increased, and the strength of the sheet is enhanced. In addition, the lithium metal particles are also expanded during the pressing process and are bonded to the polymer fibers.

Preferably, the process in step (1) is carried out under an inert gas blanket.

Preferably, the process in step (1) is carried out under low humidity conditions with a dew point of less than-40 ℃.

Preferably, the premixing method in the step (1) comprises mechanical oscillation and/or defoaming stirring.

In the method of the invention, in the first mixing process (premixing) of the fiberizable polymer and the lithium metal particles, common mixing modes such as mechanical oscillation, defoaming stirring and the like can be adopted, and the aim is to ensure that the fiberizable polymer and the lithium metal particles are fully and uniformly mixed.

Preferably, the speed of the premixing in the step (1) is 100-3000 rpm, such as 300rpm, 500rpm, 1000rpm, 1500rpm, 2000rpm or 2500rpm, and the like.

The mixing process of the invention is based on the principle of low speed first and high speed second, wherein the low speed premixing can ensure that the polymer and the lithium metal powder are fully and uniformly mixed, and the high speed stirring and shearing are the key of polymer fiberization.

Preferably, the drawing of the fiberizable polymer under shear to form fibers in step (1) comprises: at least one of high-speed stirring, screw extrusion and airflow crushing, preferably high-speed stirring, wherein the high-speed stirring speed is more than or equal to 1000 rpm; for example, 3000rpm, 5000rpm, 10000rpm, 15000rpm, 20000rpm or 25000rpm, etc., and there may be used equipment such as a crusher, a high-speed disperser, a twin-screw extruder, a jet mill, etc.

Preferably, the high speed stirring speed is 3000-25000 rpm, such as 5000rpm, 10000rpm, 15000rpm, 20000rpm or 25000 rpm.

Preferably, the high-speed stirring method is pulse stirring.

The invention adopts pulse type stirring, which is beneficial to avoiding the influence on the lithium particle powder caused by the long-time high-speed stirring to generate a large amount of heat and the untimely heat dissipation.

Preferably, the stirring time of the pulse type stirring is 2-30 min; for example, 5min, 10min, 15min, 20min or 25 min.

Preferably, the intermittent time of the pulse type stirring is 0-3 min, and does not contain 0, such as 1min or 2min and the like.

Preferably, the high-speed stirring process is accompanied by a temperature reduction treatment.

In the high-speed stirring process, the high-speed stirring is accompanied with strong frictional heat generation, and the lithium metal powder is easy to generate side reaction due to temperature rise to cause lithium metal capacity loss, so the temperature reduction treatment needs to be carried out on the material mixing tank in the process.

Preferably, the process of cold pressing treatment in the step (2) is carried out under the protection of inert gas.

Preferably, the process in step (2) is carried out under low humidity conditions with a dew point of less than-40 ℃.

Preferably, the temperature of the cold pressing treatment in step (2) is less than or equal to 25 ℃, such as 5 ℃, 10 ℃, 15 ℃ or 20 ℃ and the like.

Preferably, the cold pressing gap of the cold pressing treatment in the step (2) is 0-2 mm, such as 1 mm.

Preferably, the temperature of the hot pressing treatment in step (2) is 100 ℃ or less, such as 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃ or 90 ℃ or the like, preferably 50 ℃ to 90 ℃.

The whole process of the method is carried out in a low-humidity drying room with the dew point of less than minus 40 ℃, and the whole process is carried out at a lower temperature in order to avoid the generation of lithium byproducts; in the environment protected by inert gas, the requirement on temperature is lower, and the relatively higher temperature effect is better (the temperature is controlled within 100 ℃).

The speed of the cold pressing treatment or the hot pressing treatment in the invention can be adjusted according to the thickness of the lithium strip sheet and the product precision.

In the method, the roller can be cleaned and wiped by silicone oil in the cold pressing process, so that the roller sticking phenomenon in the cold pressing process is avoided.

As a preferred technical scheme of the invention, the preparation method comprises the following steps:

(1) under the protection of inert gas, according to the formula amount, pre-mixing a fiberizable polymer and lithium metal particles at the speed of 100-3000 rpm, and then stirring at a high speed of 3000-25000 rpm;

(2) performing cold pressing treatment on the product obtained in the step (1) at the temperature of less than or equal to 25 ℃ to a preset thickness to obtain the lithium strip;

or under the protection of inert gas, carrying out hot pressing treatment on the product obtained in the step (1) at the temperature of 50-90 ℃ to a preset thickness to obtain the lithium belt;

wherein, the processes in the step (1) and the step (2) are carried out in a low-humidity drying room with the dew point of less than minus 40 ℃.

In a third aspect, the present invention provides a lithium-supplement electrode comprising a lithium ribbon as described in the first aspect.

Preferably, the lithium supplement electrode comprises an electrode pole piece and a lithium belt bonded on the surface of the electrode pole piece.

Preferably, the electrode plate comprises a positive electrode plate or a negative electrode plate.

The negative pole piece can adopt common negative pole systems such as graphite, silicon and the like.

Preferably, the electrode sheet comprises a polymer corresponding to the polymer type in the lithium ribbon.

Preferably, the kind of polymer of the binder in the electrode plate is the same as that of the polymer in the lithium ribbon.

The types of the binder in the electrode plate and the polymer in the lithium belt are kept consistent, so that the two compatibility can be increased, and the attaching effect can be enhanced.

In a fourth aspect, the invention provides a preparation method of the lithium supplement electrode according to the third aspect, the preparation method includes laminating the lithium belt and the electrode sheet according to the first aspect, and performing cold pressing treatment to obtain the lithium supplement electrode;

or laminating the lithium belt and the electrode plate in the first aspect, and performing hot pressing treatment under the protection of inert gas to obtain the lithium supplement electrode.

According to the method, the lithium belt and the electrode pole piece are stacked together for cold pressing or hot pressing, the lithium belt and the electrode pole piece are tightly attached in the pressing process, the compaction density of the electrode pole piece is improved, and the lithium belt and the electrode pole piece can be bonded more effectively due to the existence of the same polymer.

In the method, other modes, such as a warm isostatic pressing machine, can be adopted in the rolling process of the lithium belt and the rolling and compounding process of the lithium belt and the pole piece, and the purpose is to realize the extension of the lithium belt and the uniform and close fit of the lithium belt and the pole piece.

In a fifth aspect, the present invention provides a battery comprising a lithium ribbon as described in the first aspect.

Compared with the prior art, the invention has the following beneficial effects:

(1) the lithium belt has high mechanical strength, high attaching degree with an electrode pole piece, high volatile capacity and better lithium supplementing effect;

(2) the lithium strip is used for supplementing a lithium electrode, and the battery has high first effect;

(3) the preparation method of the lithium belt has small influence on lithium metal particles, reduces the generation of lithium by-products, does not need any solvent in the preparation process, reduces the complex processes of solvent screening and solvent recovery, and reduces the cost.

Drawings

FIG. 1 is a schematic structural view of a lithium ribbon according to the present invention;

FIG. 2 is an SEM photograph of a lithium ribbon obtained in example 1 of the present invention;

FIG. 3 is an optical picture of a lithium-doped negative electrode obtained in example 2 of the present invention;

FIG. 4 is an optical picture of a purchased lithium tape used in comparative example 1 of the present invention;

FIG. 5 is a partially magnified optical picture of a purchased lithium ribbon used in comparative example 1 of the present invention;

fig. 6 is a graph comparing the effective capacities of the lithium tapes in example 1 of the present invention and comparative example 1.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

The schematic structure of the lithium ribbon of the present invention is shown in fig. 1, and as can be seen from fig. 1, the lithium ribbon comprises a polymer in a network structure (shown as white stripes in fig. 1) and lithium metal particles (shown as black fillers in fig. 1) bonded to the surface of the polymer; the arrows in fig. 1 are schematic diagrams of a top view of the schematic structure, from which it can be seen that lithium metal particles are dispersed and bound in a polymer in a network structure; the lithium belt has higher mechanical strength and improves the fitting degree of the lithium belt and an electrode pole piece; the resulting lithium tapes have higher volatile capacities.

Example 1

Mixing lithium metal particle powder and PTFE (polytetrafluoroethylene) in a drying room with the dew point of less than minus 40 ℃, and stirring and dispersing for 5min at the stirring speed of 2000rpm to fully and uniformly mix the lithium metal powder and the polymer; then high-speed shearing stirring is carried out at the speed of 20000rpm, pulse type stirring is adopted, the stirring time is 1min, the rest time is 1min, and the total stirring time is 20min, so as to obtain dry powder;

the dry powder comprises the following components by mass percent of 100 percent:

95% of lithium metal particle powder

PTFE 5％；

Taking quantitative dry-process powder, placing the dry-process powder on rolling equipment with adjustable roller gaps, cleaning and wiping the roller by using silicone oil to avoid the roller sticking phenomenon in the cold pressing process, preparing a self-supporting lithium belt with the thickness of 13 mu m at the rolling speed of 5rpm in the roller gap of 10 mu m, and controlling the cold pressing temperature to be 20 ℃;

the effective capacity of the composite material reaches 3450mAh/g through testing.

The SEM image of the self-supporting lithium ribbon obtained in this example is shown in fig. 2, and it can be seen from fig. 2 that the lithium ribbon comprises a polymer in a network structure and lithium metal particles bonded to the surface of the polymer.

Example 2

Mixing lithium metal particle powder and PTFE (polytetrafluoroethylene) in a drying room with the dew point of less than minus 40 ℃, and stirring and dispersing for 5min at the stirring speed of 2500rpm to fully and uniformly mix the lithium metal powder and the polymer; then carrying out high-speed shearing stirring at the speed of 22000rpm, and carrying out pulse type stirring for 1min, stopping time for 1min and total stirring time for 20min to obtain dry powder;

90 percent of lithium metal particle powder

PTFE 10％；

Taking quantitative dry-process powder, placing the dry-process powder on rolling equipment with adjustable roller gaps, cleaning and wiping the rollers by using silicone oil to avoid roller sticking in the cold pressing process, preparing a self-supporting lithium belt with the thickness of about 7 microns at the rolling speed of 5rpm in the roller gaps of 5 microns, and controlling the cold pressing temperature to be 20 ℃;

stacking the obtained self-supporting lithium belt and a dry-method cathode together for cold pressing, wherein the cold pressing temperature is 20 ℃; adjusting the gap between the rollers to be 85 mu m, and the rolling speed to be 5rpm, so as to finally obtain the negative pole piece with the compacted density of 1.7 g/cc; the lithium belt is tightly attached to the pole piece to obtain a lithium supplement pole piece, and the overall thickness of the lithium supplement pole piece is 88 microns;

the preparation method of the dry-method cathode comprises the following steps: 1) premixing a negative active material and a conductive agent; 2) adding the PTFE adhesive and then continuously shearing and mixing; 3) hot pressing the powder to form a film and compounding the film with a current collector;

through the test of assembling single-chip battery cell, the first effect of the battery cell reaches 93.5 percent.

An optical picture of the lithium-supplement negative electrode obtained in the embodiment is shown in fig. 3, and as can be seen from fig. 3, the prepared lithium-supplement negative electrode has a flat surface and is in a metallic luster; and is closely attached to the negative electrode.

Example 3

The present example differs from example 1 in that the dry powder comprises the following components, based on 100% by mass of the dry powder:

10% of lithium metal particle powder

PTFE 90％；

Other parameters and conditions were exactly the same as in example 1.

Example 4

60 percent of lithium metal particle powder

PTFE 40％；

Other parameters and conditions were exactly the same as in example 1.

Example 5

30 percent of lithium metal particle powder

PTFE 70％；

Other parameters and conditions were exactly the same as in example 1.

The lithium tapes obtained in examples 3 to 5 all had good mechanical stability and were able to form self-supporting structures.

Example 6

The present example is different from example 1 in that the lithium ribbon is prepared by hot pressing under argon atmosphere at 80 deg.c, and other parameters and conditions are the same as those in example 1.

Example 7

The present example is different from example 1 in that after mixing lithium metal particle powder and PTFE, high-speed shear stirring was carried out at 20000rpm as it is, and other parameters and conditions were exactly the same as those in example 1.

Example 8

This example is different from example 1 in that the speed of high-speed shearing was replaced with 5000rpm and other parameters and conditions were exactly the same as in example 1.

Example 9

This example is different from example 1 in that the speed of high-speed shearing was replaced with 10000rpm, and other parameters and conditions were exactly the same as those in example 1.

Example 10

This example is different from example 1 in that the speed of high-speed shearing was replaced with 2000rpm and other parameters and conditions were exactly the same as in example 1.

Comparative example 1

The ultrathin lithium belt purchased from a certain domestic manufacturer has a plastic film as a support body, the thickness of the lithium belt is 5 mu m, the thickness of the plastic film is about 50 mu m, and the lithium belt is flatly paved on the surface of the plastic film. And a small number of pores may be present on the surface thereof as shown in fig. 4 and 5, which is caused by too weak strength of the thin lithium ribbon itself.

The dry-method cathode in the embodiment 2 is adopted, the lithium band in the comparative example is adopted for lithium supplement, and then the battery cell is obtained through assembly, wherein the assembly method is the same as that in the embodiment 2; the first effect was tested to be 89.5%.

The verification curves of the effective capacity of the lithium tapes in example 1 and comparative example 1 are shown in fig. 6, and it can be seen from fig. 6 that the lithium tapes of the present invention have higher playable capacity, and the generation of more failure capacity of lithium metal is avoided during the production process.

Comparative example 2

The comparative example is different from example 1 in that the lithium metal particle powder and PTFE were stirred and mixed at a speed of 500rpm without high-speed shearing, and other parameters and conditions were exactly the same as those in example 1, and the lithium ribbon was extremely uneven and could not be used normally.

Comparative example 3

In the comparative example, the dry-method negative electrode which does not contain the lithium tape in the example 2 is used as a blank control, and the battery cell is assembled by the dry-method negative electrode, wherein the battery cell assembling method is completely the same as that in the example 2;

the first effect of the cell test obtained by the comparative example is only 83 percent.

And (3) performance testing:

testing the effective capacity of the lithium tapes obtained in the examples and the comparative examples, and assembling the lithium tapes with a dry-method negative electrode to obtain a lithium-supplement negative electrode; further assembling the single battery cell, and carrying out a first effect test, wherein the first effect test takes the example 2 and the comparative example 1 as an example;

the assembling method of the single-chip battery cell comprises the following steps: the positive electrode piece adopts a conventional wet positive electrode piece, the diaphragm adopts a common ceramic diaphragm, the negative electrode piece adopts the lithium-supplementing negative electrode, and the electrolyte adopts a conventional commercial electrolyte (lithium salt is LiPF)₆The concentration is 1.5mol/L, and the solvent is ethylene carbonate: ethyl methyl carbonate: the volume ratio of dimethyl carbonate is 2: 2: 4; the additive is fluoroethylene carbonate (FEC) with the mass ratio of 7 percent;

the lithium belt effective capacity test method comprises the following steps: lithium strips were used as working electrodes. A lithium sheet is used as a reference electrode; the current density is 0.1C, and the constant current charging is carried out until the voltage is 3.0V;

the first effect test method comprises the steps of charging to 4.25V at a constant current and a constant voltage of 0.1C, and discharging to 2.5V at a constant current of 0.1C.

The above-mentioned effective capacity test results are shown in table 1;

TABLE 1

	Effective capacity/mAh/g
		Example 1	3450
Example 2	3400
		Example 6	3510
Example 7	3420
		Example 8	3190
Example 9	3380
		Example 10	3100
Comparative example 1	3280

In the examples in the table above, the effective capacity is based on the total mass of the lithium tape (which contains lithium metal and polymer), the lithium tape in comparative example 1 is a pure lithium tape, and the calculation of the effective capacity does not contain polymer; that is, on the premise that the calculated effective capacities are the same, the lithium metal in the lithium ribbon of the present invention has a higher effective capacity.

As can be seen from the above table 1, the lithium tape of the present invention has a lower failure capacity, and thus can exert a higher capacity, up to 3510 mAh/g; and it has a higher mechanical stability. The lithium tape of comparative example 1 had a problem of insufficient effective capacity and poor mechanical stability.

As can be seen from comparison of examples 1 and 6, lithium tapes having high mechanical stability can be obtained by cold pressing or hot pressing after high shear, and both have high effective capacities.

Comparative examples 1, 7-10 it can be seen that the lithium ribbon polymers of the present invention have high mechanical stability and can exert capacity.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.

Claims

1. A lithium ribbon comprising a polymer in a network structure and lithium metal particles bonded to the surface of the polymer;

the polymer with the network structure is formed by drawing a fiberizable polymer under the action of shearing force to form fibers and mutually lapping the fibers in the cold pressing treatment or hot pressing treatment process;

the lithium ribbon is prepared by a preparation method which comprises the following steps:

2. The lithium ribbon according to claim 1, wherein the thickness of the lithium ribbon is 1 to 500 μm.

3. The lithium ribbon of claim 1, wherein the lithium ribbon is a self-supporting lithium ribbon.

4. The lithium ribbon of claim 1, wherein the fiberizable polymer comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyimide, polyacrylonitrile, polypropylene, polyethylene, polystyrene, and polyacrylic acid.

5. The lithium ribbon according to claim 1, wherein the polymer having a network structure is contained in the lithium ribbon in an amount of 3 to 90% by mass based on 100% by mass of the lithium ribbon.

6. The lithium ribbon according to claim 1, wherein the polymer having a network structure is contained in the lithium ribbon in an amount of 5 to 15% by mass based on 100% by mass of the lithium ribbon.

7. The lithium ribbon according to claim 1, wherein the lithium metal particles are contained in the lithium ribbon in a mass percentage of 10 to 97% based on 100% by mass of the lithium ribbon.

8. The lithium ribbon of claim 1, wherein the lithium metal particles are present in the lithium ribbon in a mass percent of 85% to 95% based on 100% by mass of the lithium ribbon.

9. The method of manufacturing a lithium strip according to any one of claims 1 to 8, comprising the steps of:

10. The method according to claim 9, wherein the process in step (1) is carried out under an inert gas atmosphere.

11. The method of claim 9, wherein the process in step (1) is carried out under low humidity conditions with a dew point of less than-40 ℃.

12. The method of claim 9, wherein the premixing in step (1) comprises mechanical agitation and/or debubbling.

13. The method of claim 9, wherein the pre-mixing in step (1) is performed at a speed of 100 to 3000 rpm.

14. The method of claim 9, wherein the drawing the fiberizable polymer under shear to form fibers of step (1) comprises: at least one of high speed stirring, screw extrusion, and jet milling.

15. The method of claim 14, wherein the step (1) of drawing the fiberizable polymer into fibers under shear is by high-speed stirring at a speed of 1000rpm or more.

16. The method of claim 14, wherein the high speed agitation is at a speed of 3000 to 25000 rpm.

17. The method of claim 14, wherein the high speed agitation is pulsed agitation.

18. The method of claim 17, wherein the pulsed agitation is performed for a period of time of 2 to 30 min.

19. The method of claim 17, wherein the pulsed agitation is applied for a period of 0 to 3 minutes, excluding 0.

20. The method according to claim 9, wherein the cold pressing in step (2) is performed under an inert gas atmosphere.

21. The method of claim 9, wherein the process in step (2) is carried out under low humidity conditions with a dew point of less than-40 ℃.

22. The method of claim 9, wherein the cold pressing treatment of step (2) is performed at a temperature of 25 ℃ or less.

23. The preparation method according to claim 9, wherein the cold pressing gap of the cold pressing treatment in the step (2) is 0-2 mm.

24. The method of claim 9, wherein the hot pressing temperature in step (2) is 100 ℃.

25. The method of claim 24, wherein the temperature of the hot pressing in the step (2) is 50 ℃ to 90 ℃.

26. The method of claim 9, comprising the steps of:

(2) performing cold pressing treatment on the product stirred at high speed in the step (1) at the temperature of less than or equal to 25 ℃ to a preset thickness to obtain the lithium belt;

or under the protection of inert gas, carrying out hot pressing treatment on the product stirred at high speed in the step (1) at the temperature of 50-90 ℃ to a preset thickness to obtain the lithium belt;

27. A lithium-replenishing electrode comprising the lithium ribbon according to any one of claims 1 to 8.

28. The lithium-doped electrode of claim 27, wherein the lithium-doped electrode comprises an electrode tab and a lithium ribbon bonded to a surface of the electrode tab.

29. The lithium-ion rechargeable electrode of claim 28, wherein the electrode tab comprises a positive electrode tab or a negative electrode tab.

30. The lithium rechargeable electrode of claim 28, wherein the electrode tab includes a polymer corresponding to the polymer type in the lithium ribbon.

31. The method for preparing the lithium-supplement electrode according to any one of claims 28 to 30, which comprises the steps of laminating the lithium strip according to any one of claims 1 to 8 and the electrode sheet, and performing cold pressing treatment to obtain the lithium-supplement electrode;

or laminating the lithium belt and the electrode pole piece according to any one of claims 1 to 8, and performing hot pressing treatment under the protection of inert gas to obtain the lithium supplement electrode.

32. The method of claim 31, wherein the cold pressing process is performed at a temperature of 25 ℃ or less.

33. The method of claim 31, wherein the temperature of the hot pressing is 100 ℃ or less.

34. The method of claim 33, wherein the hot pressing temperature is 50 to 90 ℃.

35. A battery comprising a lithium ribbon according to any one of claims 1 to 8.