WO2022116075A1

WO2022116075A1 - Ultra-thin lithium film composite and preparation method therefor

Info

Publication number: WO2022116075A1
Application number: PCT/CN2020/133535
Authority: WO
Inventors: 孙兆勇; 陈强; 郇庆娜; 孔德钰; 刘承浩
Original assignee: 天津中能锂业有限公司
Priority date: 2020-12-03
Filing date: 2020-12-03
Publication date: 2022-06-09

Abstract

The present invention provides an ultra-thin lithium film composite and a preparation method therefor. The composite has a bearing layer, a stress control layer located on at least one surface of the bearing layer, and an ultra-thin lithium film bonded to the bearing layer by means of the stress control layer. The ultra-thin lithium film is a uniform thin film having through holes with a pore diameter of 5-200 micrometers, the thickness tolerance is within ±0.5 μm, and the bonding force between the ultra-thin lithium film and the bearing layer is 0.5-15 N·m^-1.

Description

Ultrathin lithium film composite and preparation method thereof

technical field

The invention relates to the technical field of energy storage, in particular to an ultra-thin lithium film composite that can be used in secondary batteries and a preparation method thereof.

Background technique

Lithium batteries are widely used in aerospace, computers, mobile communication equipment, robots and electric vehicles due to their high energy density, long cycle life and wide temperature range. With the development of society and the advancement of science and technology, the requirements for the energy density and cycle life of lithium batteries are getting higher and higher. At present, lithium-ion batteries with graphite as the negative electrode are difficult to meet the expectations of the society. Therefore, it is necessary to develop new models with higher ratios. capacity of positive and negative materials. For negative electrode materials, pre-lithiation work can effectively improve the specific energy of the battery and increase the battery life. Li metal has a high specific capacity (3860mAh/g, 10 times that of graphite anode) and the lowest redox potential (-3.04V VS standard hydrogen potential). The use of metal lithium to pre-lithiate the traditional graphite negative electrode can improve the first coulombic efficiency of the battery and increase the specific energy of the battery on the one hand, and can effectively prolong the cycle life of the battery on the other hand, which makes the lithium-ion battery have a wider application. field.

Although pre-lithiation (lithium compensation) has such advantages, in order to precisely control its amount in the battery, higher requirements are placed on the pre-lithiation of the negative electrode. At present, the cathode materials used in existing lithium-ion batteries are all lithium-containing materials (such as lithium cobalt oxide, lithium iron phosphate, ternary materials, etc.). The energy density and cycle life of the battery can be improved by only supplying a small amount of lithium to compensate for the lithium loss during cycling. Since the amount of pre-intercalated lithium in the negative electrode is very small, the thickness of the lithium film used for lithium supplementation is usually only 0.5 μm to 15 μm. In the Chinese patent application CN201610102992.8 of Ningde Times New Energy, lithium powder is sprinkled on the surface of the pole piece during the lithium replenishment process, and pre-lithiation is performed after rolling, and the amount of lithium is very small. However, this method of supplementing lithium cannot achieve precise control of the amount of lithium supplementing, and the process is complicated, the cost is high, and more importantly, the safety is difficult to control. In view of this, a technology that can control the amount of lithium supplementation and achieve high energy density of the battery is required.

SUMMARY OF THE INVENTION

The inventors found that when the ultra-thin lithium film is compounded on the carrier layer by a rolling process, the ultra-thin lithium film is not easy to be firmly attached to the carrier layer due to the large difference in properties between the surface of the carrier layer (such as a plastic material) and the surface of metal lithium. On the surface, if a large pressure (stress) is applied for firm adhesion, it is easy to cause fracture of the ultra-thin lithium film or incomplete surface shape (broken or uneven pores). For this reason, the inventors have made in-depth and meticulous research, and unexpectedly found that: by forming a specific stress control layer on the surface of the carrier layer, not only the surface property difference between the carrier layer and metal lithium can be alleviated, but the ultra-thin lithium film can be more easily attached to the surface. It can also reduce the stress effect during rolling, so that the ultra-thin lithium film can maintain a better surface morphology. In addition, the stress control layer can also control the adhesion between the ultra-thin lithium film and the carrier layer to make it at a suitable level, which can not only ensure that the ultra-thin lithium film can be compounded on the carrier layer, but also can be easily transferred from the carrier layer. onto other substrates such as lithium battery negative electrodes. The inventor also unexpectedly found that for the lithium film used for the pre-lithiation of the negative electrode, if the lithium film has through holes, the presence of the holes can not only make it easier for the electrolyte to enter the contact interface between the lithium film and the negative electrode film, but also improve the performance of the lithium film. Pre-lithiation speed, and the gas generated during pre-lithiation can be released from the through hole to avoid the separation of the lithium film and the negative electrode film. Therefore, the lithium film with through-holes can achieve better prelithiation effect than the complete lithium film. Therefore, ultra-thin lithium films (0.5-20 microns thick, or even 1-5 microns thick) with through-holes can be produced in a roll-to-roll manner by rolling. Due to the existence of through holes, the accumulation of internal stress of the lithium film during rolling is alleviated to a certain extent, so that the lithium film is not easily deformed, so that a thinner lithium film with uniform thickness (for example, 1-5 microns) can be prepared. Based on these findings, the present invention has been completed.

Therefore, one aspect of the present invention is to provide an ultra-thin lithium film composite having: a support layer; a stress control layer on at least one surface of the support layer; An ultra-thin lithium film in which the stress control layer and the bearing layer are composited together, wherein the ultra-thin lithium film is a uniform thin film having through holes with a pore diameter of 5-200 microns, and has a uniform thickness of 0.5-20 microns. The tolerance is within ±0.5 μm; the adhesive force between the ultra-thin lithium film and the carrier layer is 0.5-15 N·m ⁻¹ .

In the present invention, the ultra-thin lithium film is a uniform film means that the ultra-thin lithium film has a complete film shape (without obvious wrinkles and deformation, and has neat edges) and has a uniform thickness. Preferably, the ultra-thin lithium film has through-holes that are uniformly distributed throughout the lithium film.

Optionally, the ultrathin lithium film of the present invention is continuous or intermittent in the length direction; or continuous or intermittent in the width direction.

Optionally, the intermittent lithium film in the length direction includes a blank area with controllable length and a metal lithium layer area, the length of the metal lithium layer area is 1-2000mm, and the length of the blank area is 1-200mm, preferably 1-100mm.

Optionally, for the intermittent lithium film in the width direction, the width of the lithium film portion is 1-200 mm, and the intermittent portion of the lithium film has a spacing of 0.5-10 mm.

Optionally, the surface of the lithium film of the ultra-thin lithium film composite is bright and metallic silver white, the lithium content is 99.90-99.95%, and the lithium element content of the main body (inside) of the lithium film may be 99.95%-99.99%. The thickness of the lithium film is in the range of 0.5-15 μm, preferably 1-10 μm, more preferably 5 μm or less, and the thickness tolerance is ±0.5 μm, preferably ±0.1 μm.

Optionally, the ultra-thin lithium film has uniformly distributed through-holes with a pore size of 5-200 microns, preferably 10-50 microns.

Optionally, the porosity of the ultra-thin lithium film is 0.1%-20%, preferably 0.1%-10%, more preferably 0.5%-5%.

Optionally, the shape of the through hole of the ultra-thin lithium film is a circular hole or a quasi-circular hole, and the hole spacing is 5-1000 microns, preferably 5-200 microns, more preferably 5-50 microns.

Optionally, the carrier layer material is a polymer: such as polyimide, nylon, cellulose, high-strength filmed polyolefin (polyethylene, polypropylene, polystyrene); polyester (polyethylene terephthalate) glycol esters, polybutylene terephthalate, polyarylate); inorganic oxides: such as aluminum oxide; inorganic conductors: such as graphite, carbon nanotubes, graphene; metal current collectors: such as copper, aluminum; The carrier layer can be a single layer or a multi-layer composite.

Optionally, the thickness of the carrier layer is 1-500 microns, preferably 5-100 microns, more preferably 10-50 microns.

Optionally, the stress control layer is formed of a stress adjustment material, or formed by surface treating the carrier layer with a stress adjustment material.

Alternatively, the stress control layer is formed by spray coating, dip coating, transfer coating, extrusion coating, knife coating, curtain coating, screen printing or vapor deposition of a stress regulating material on the carrier layer.

Optionally, the thickness of the stress control layer is 50-200 nm.

Optionally, the stress-adjusting material includes vinyl dimethyl polysiloxane, hydrogen-containing silicone oil, punching oil, liquid paraffin, methyl silicone oil, emulsified methyl silicone oil, hydrogen-containing methyl silicone oil, silicone grease, polyethylene wax A combination of one or more of.

Optionally, the stress-adjusting material can be used alone or dissolved in a solvent to form a solution.

Optionally, the solvent used for the stress-adjusting material solution includes: toluene, n-butanol, polyvinyl alcohol, methyl ethyl ketone, n-hexane, or a combination of one or more.

Optionally, the adhesive force between the carrier layer and the ultra-thin lithium film is 1-10 N·m ^-1 , preferably 1-5 N·m ^-1 . The adhesion between the carrier layer and the ultra-thin lithium film can ensure that the ultra-thin lithium film is stably compounded on the carrier layer, and can be easily transferred from the carrier layer to other substrates such as the negative electrode of a lithium battery.

Another aspect of the present invention aims to provide a method for preparing the above-mentioned ultra-thin lithium film composite, which is characterized in that a roll-to-roll continuous production method is adopted, a metal lithium strip with a thickness of 10-250 μm is used as a raw material, and a In the rolling method, the metal lithium strip is rolled and compounded on the stress control layer of the bearing layer with the stress control layer to obtain the ultra-thin lithium film compound.

Optionally, the thickness of the metallic lithium strip is 10-100 μm, preferably 10-50 μm.

Optionally, the rolling includes cold rolling, hot rolling and clad rolling, wherein the temperature of the hot rolling is controlled in the range of 60-120° C., and the clad rolling is preferably first hot rolled and then cold rolled.

Optionally, the pressure range of rolling is 0.1-150Mpa, preferably 80-120Mpa.

Optionally, the adhesion force between the ultra-thin lithium film and the carrier layer is controlled by controlling the stress control layer, so that the adhesion force is 0.5-15 N/m.

Optionally, the surface of the roller is provided with a release material, and the release material includes polyethylene, polyoxymethylene, organic silicon polymer, and ceramics.

Optionally, a roller with a maximum tension range of 0.1-10N is used for winding, and the backup roller itself is powered.

By providing the stress control layer and controlling the rolling process, the present invention obtains a composite body loaded with a uniform ultra-thin lithium film with through holes in a simple process, and the ultra-thin lithium film with through holes of the composite body can be easily It is transferred to the negative electrode of lithium battery, and has an improved pre-lithiation effect to achieve high energy density of the battery.

Description of drawings

FIG. 1 is a schematic diagram of a process for producing continuous ultra-thin lithium film composites by pressure composite according to the present invention.

FIG. 2 is a schematic diagram of an intermittent ultrathin lithium film composite in the width direction.

FIG. 3 is a schematic diagram of a longitudinally intermittent ultrathin lithium film composite.

Figure 4 shows a schematic diagram of the process for producing intermittent ultrathin lithium film composites.

FIG. 5 shows the 5-micron-thick ultra-thin lithium film composite product prepared in Example 1 of the present application.

FIG. 6 shows the 10-micron-thick ultra-thin lithium film composite product prepared in Example 2 of the present application.

FIG. 7 shows the 5-micron intermittent ultra-thin lithium film composite product prepared in Example 3 of the present application.

FIG. 8 shows the negative electrode product after graphite pre-lithiation in Example 4 of the present application.

FIG. 9 shows the negative electrode product after silicon carbon pre-lithiation in Example 5 of the present application.

FIG. 10 shows the ultra-thin lithium film composite and graphite pre-lithium post-lithium anode product without using the stress control layer in Comparative Example 1.

Abbreviation:

P Substrate L Metal Lithium Layer PL (Continuous) Lithium Foil PNL Intermittent Lithium Foil

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

FIG. 1 shows a schematic diagram of a process for producing a continuous ultra-thin lithium film composite by pressure composite according to the present invention. As shown in FIG. 1 , using a metal lithium strip and a support strip (with a stress control layer on one side of the support strip) as raw materials, unwinding is carried out by an unwinding device, and the unwinding device at least includes a metal lithium strip A material unwinding roller 11 and two unwinding support rollers 12 for supporting the unwinding metal lithium belt and the supporting belt respectively; the raw material lithium belt and the supporting belt (the stress control layer of the supporting belt faces the The strip) enters the rolling mill 20 after passing through the unwinding backup roll 12; the rolling mill 20 includes at least a pair of rolls 21 and an anti-stick coating 22 on the rolls 21, the rolling pressure of the rolling mill 20 and the roll gap between the rolls 21 can be Fine-tuning; the material of the release coating 22 on the roller 21 can be selected from one or more of polyethylene, polyoxymethylene, silicone polymer, ceramics, and the like. After pressure compounding, the carrier tape and the lithium material are compounded together to form an ultra-thin lithium film compound product. The outlet side of the rolling mill 20 is provided with a winding device, the winding device at least includes a support roll 31, a tension control roll 32 and a winding roll 33; wherein the support roll 31 is powered, and the ultra-thin lithium film can be composited with a small tension force The tension control roller 32 can move up and down or swing, which can not only control the tension of the composite body, but also control the winding speed of the winding roller 33 according to the height or swing angle of the tension control roller 32 .

FIG. 2 is a schematic diagram of the intermittent lithium film in the width direction, and FIG. 3 is a schematic diagram of the intermittent lithium film in the length direction.

FIG. 4 is a schematic diagram of a production device for producing intermittent lithium film. The intermittent lithium foil production device includes an unwinding device 100, a scraping device 200 and a winding device 300, and also includes controlling the winding speed and the working time interval of the scraping device. control device (not shown). The unwinding device 100 includes an unwinding shaft 101, a magnetic powder brake 102, an unwinding support roller 104, an unwinding correction detection sensor 105, and an unwinding correction device 103; the scraping device 200 includes a scraper 201, a scraper driving device 202, and a scraper pad 203 and support rollers (204, 205); the winding device 300 includes a winding shaft 301, a winding motor 302, a winding rectification device 303, a winding support roller 304 and a winding rectification detection sensor 305; in addition, optionally also provided There is a length measuring sensor 401 .

The unwinding shaft 101 on the unwinding device 100 is used for unwinding the lithium foil PL, and the magnetic powder brake 102 connected with the unwinding shaft 101 can control the size of the unwinding tension; the unwinding support roller 104 is used to support the lithium foil PL at a constant inclination angle Entering the scraping device 200 and facilitating the unwinding, the correction detection sensor 105 accurately performs correction detection on the lithium foil PL. The support rollers 204/205 on the scraping device 200 respectively ensure that the inclination angle of the strip entering and exiting the device is constant, and is not affected by other process links; the scraper pad 203 is used to support the lithium foil PL and maintain the flat state of the lithium foil PL; the scraper drives The device 202 is used to drive the scraper 201 to achieve rapid movement in the up-down direction. The winding device 300 includes a winding shaft 301 and a winding motor 302 ; the winding shaft 301 is used for intermittently winding the lithium foil PNL, and the winding shaft 301 is driven by the winding motor 302 .

The specific use method and process are as follows: install the lithium foil PL supported by the base material on the unwinding shaft 101 and fix it; pass the lithium foil PL through the unwinding support roller 104, the unwinding correction detection sensor 105, and the support of the scraping device in sequence The

rollers

204 and 205, the rewinding correction detection sensor 305, and the rewinding support roller 304 are then wound on the reeling shaft 301 and fixed. Turn on the equipment, make the winding motor 302 on the winding device 300 run, and drive the winding shaft 301 to rotate, so that the lithium foil PL can be wound from the end of the unwinding device 100 through the scraping device 200; During the rolling process, the scraper 201 is intermittently moved up and down by controlling the scraper driving device 202 in the scraping device 200 to scrape off part of the lithium metal layer on the lithium foil PL to form an intermittent lithium foil PNL. The width and number are used to produce interstitial lithium films in the width direction or the length direction.

Hereinafter, the present invention will be described in more detail by way of examples using the above-mentioned process equipment. The various product structural parameters, various reaction participants and process conditions used in the following examples are all typical examples, but after a large number of experiments and verifications by the inventor of the present application, the other different structural parameters listed above , other types of reaction participants and other process conditions are also applicable, and can also achieve the technical effect claimed by the present invention.

Example 1:

A metal lithium strip with a lithium content of 99.95% and a thickness of 20 microns and a polyethylene film with a thickness of 50 microns were used (the surface of the polyethylene film has the contact surface of the carrier layer and the metal lithium sprayed with the methyl ethyl ketone solution containing hydrogen silicone oil. Formed stress control layer), auxiliary unwinding and rewinding device, using cold rolling method, controlled pressure 100Mpa, to obtain ultra-thin lithium film composite products with a thickness of 5 microns (thickness tolerance of ± 0.5 microns).

Figure 5 is a photo of the ultra-thin lithium film composite product (the light source is irradiated from one side of the carrier layer, that is, the light source is irradiated from the inside of the composite body, and the light intensity is large and illuminated from the back to show the through hole, and the highlighted part in the middle is is the direct light source). As can be seen from Figure 5, the ultra-thin lithium film has a relatively complete film shape, and the film has relatively evenly distributed pinhole-shaped (penetrating film) through holes, the size of the holes is 5-50 microns, and the hole spacing is 5- 100 microns.

Example 2:

A metal lithium strip with a lithium content of 99.95% and a thickness of 20 microns and a copper foil with a thickness of 10 microns (the surface of the copper foil has a surface formed by spraying the contact surface between the carrier layer and the metal lithium with a paraffin-containing n-butane solution) were used. Stress control layer), auxiliary unwinding, rewinding device and scraping device, using hot rolling method, temperature 80 ℃, control pressure 120Mpa, to obtain intermittent ultra-thin lithium with a thickness of 10 microns (thickness tolerance of ± 0.5 microns) in the length direction Membrane composite products (Figure 6).

Example 3:

A metal lithium strip with a lithium content of 99.95% and a thickness of 20 microns and a polyethylene film with a thickness of 50 microns (the surface of the polyethylene film has a stress control formed by spraying the contact surface between the carrier layer and the metal lithium with punching and shearing oil) are used. layer), auxiliary unwinding, winding device and scraping device, using hot rolling method, temperature 80 ℃, control pressure 120Mpa, to obtain intermittent ultra-thin lithium film composite with a thickness of 5 microns (thickness tolerance of ± 0.5 microns) in the width direction body products (see Figure 7).

Example 4-Graphite Supplementing Lithium Test:

First prepare a graphite electrode, mix graphite powder (Betterui): acetylene black AB (Betterui): sodium carboxymethyl cellulose CMC (Shanghai Haiyi): styrene-butadiene rubber SBR (Shanghai Haiyi) = 94:3: 1:2, dispersed in deionized water, controlled solid content 35%, viscosity 2000-3000cp, stirring time 6h, coated on 10μm copper film on one side with a coating machine, and dried to obtain 50μm graphite pole piece. Then use the 10-micron ultra-thin lithium composite product intermittently in the width direction obtained in Example 3, treat the stress control layer (control the adhesion force 2N/m), and transfer the lithium film bonding pressure to the surface of the graphite electrode with a pressure of 15MPa ( As shown in Figure 8), peel off the carrier layer, punch into a pole piece with a diameter of 15.6cm, and form a half-cell with the lithium film, using 1M LiPF6, EC/DMC/EMC (1/1/1) (Shanshan electrolyte) as the electrolytic solution liquid. Compared with the half-cell without pre-lithiation, in the half-cell pre-lithiated graphite anode by using ultra-thin lithium composite, the first-time efficiency of the graphite anode is increased from 92% to 100%, and the first-time efficiency is greatly improved .

Example 5-Silicon carbon lithium supplementation test

First prepare a silicon carbon electrode, mix silicon carbon powder (Betterui): acetylene black AB (Betterui): sodium carboxymethyl cellulose CMC (Shanghai Haiyi): styrene-butadiene rubber SBR (Shanghai Haiyi) = 94: 4:1:2, dispersed in deionized water, controlled solid content 38%, viscosity 2000-3000cp, stirring time 6h, coated on 10μm copper film on one side with a coating machine, and dried to obtain 50μm silicon carbon pole piece . Then use the 5-micron ultra-thin lithium composite product obtained in Example 1, stress control layer treatment (controlling the adhesion force 3N/m), and use 15MPa pressure to transfer the lithium film to the surface of the silicon carbon electrode (as shown in Figure 9) , peel off the carrier layer, punch into a pole piece with a diameter of 15.6cm, and form a half-cell with the lithium film, using 1M LiPF6, EC/DMC/EMC (1/1/1) (Shanshan electrolyte) as the electrolyte. Compared with the half-cell without pre-lithiation, in the half-cell pre-lithiation of the silicon-carbon anode by using the ultra-thin lithium composite, the first-time efficiency of the silicon-carbon anode is increased from 76% to 95%, and the first-time efficiency is large. increase in magnitude.

Comparative Example 1:

Using lithium metal strip with a lithium content of 99.95% and a thickness of 20 microns and a polyethylene film with a thickness of 50 microns (the film is not subjected to controlled stress treatment), auxiliary unwinding and rewinding device, cold rolling method, control pressure 100Mpa , the obtained ultra-thin lithium film composite product with a thickness of 5 microns (thickness tolerance of ± 0.5 microns) cannot be smoothly transferred to the pole piece. In the process of separating the carrier layer, the pole piece will be damaged and the active material will fall off , as shown in Figure 10.

Performance Testing:

Using the American AR-1000 universal adhesion tester, test temperature: 25±5℃, speed: 15cm/min, test angle: 120°, adhere to the ultra-thin lithium film by 3M tape, fix the bearing layer, pass Pull the force to separate, and test the pulling force when separating. The adhesive force of the ultra-thin metal lithium composites produced in Examples 1-5 and Comparative Example 1 was tested, and the results are shown in Table 1.

Adhesion Test Table 1

序号serial number	产品名称product name	锂膜状态Lithium film state	粘结力(N/m)Adhesion (N/m)
11	实施例1Example 1	连续continuous	22
22	实施例2Example 2	间歇intermittent	1010
33	实施例3Example 3	间歇intermittent	33
44	实施例4Example 4	间歇intermittent	33
55	实施例5Example 5	连续continuous	22
66	比较例Comparative example	连续continuous	2020

It can be seen from Table 1 that the adhesive force can be effectively controlled through the stress control layer, so that the adhesive force between the pole piece and the lithium film is greater than that between the lithium film and the carrier layer, resulting in effective lithium film products. Transfer to the negative side of the battery.

It should be understood that the above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the present invention. within the scope of protection of the invention.

Claims

An ultra-thin lithium film composite, characterized in that the composite has:

bearing layer;

a stress control layer on at least one surface of the carrier layer; and

Through the ultra-thin lithium film composited with the stress control layer and the carrier layer,

in,

The ultra-thin lithium film is a uniform film having through holes with a diameter of 5-200 microns, a uniform thickness of 0.5-20 microns, and a thickness tolerance within ±0.5 μm;

The adhesive force between the ultra-thin lithium film and the carrier layer is 0.5-15 N·m -1 .
The ultra-thin lithium film composite according to claim 1, wherein: the ultra-thin lithium film is continuous or intermittent in the length direction; or the ultra-thin lithium film is continuous or intermittent in the width direction .
The ultra-thin lithium film composite according to claim 2, wherein:

The ultra-thin lithium film intermittently in the length direction includes a length-controllable blank area and a metal lithium layer area, the length of the metal lithium layer area is 1-2000mm, and the length of the blank area is 1-200mm;

The ultrathin lithium film intermittently in the width direction has ultrathin lithium film portions with a width in the range of 1-200 mm, and the intermittent portion between the lithium films has a width of 0.5-10 mm.
The ultra-thin lithium film composite according to claim 1, wherein the ultra-thin lithium film satisfies at least one of the following conditions:

The porosity is 0.1%-20%, preferably 0.1%-10%, more preferably 0.5%-5%;

The shape of the through hole is a round hole or a round hole;

The through hole spacing is 5-1000 microns, preferably 5-200 microns, more preferably 5-50 microns;

The thickness of the ultra-thin lithium film is 1-10 microns.
The ultra-thin lithium film composite according to claim 1, wherein the stress adjusting material used to form the stress control layer comprises: vinyl dimethyl polysiloxane, hydrogen-containing silicone oil, punching and shearing oil, A combination of one or more of liquid paraffin, methyl silicone oil, emulsified methyl silicone oil, hydrogen-containing methyl silicone oil, silicone grease, and polyethylene wax.
The ultra-thin lithium film composite according to claim 5, wherein the stress-adjusting material is coated on at least one surface of the carrier layer in the form of a solution, and the solvent used comprises: toluene, n-butanol, polymer A combination of one or more of vinyl alcohol, butanone, and n-hexane.
The ultra-thin lithium film composite according to claim 1, wherein the material of the bearing layer is a polymer: polyimide, nylon, cellulose, high-strength thin-film polyolefin (polyethylene, polypropylene , polystyrene), polyester (polyethylene terephthalate, polybutylene terephthalate, polyarylate); inorganic oxide: aluminum oxide; inorganic conductor: graphite, carbon nanotubes , graphene; metal current collectors: copper, aluminum; the bearing layer is a single-layer or multi-layer composite.
A method for preparing the ultra-thin lithium film composite according to any one of claims 1-7, characterized in that: the method is a roll-to-roll continuous production method, and a metal lithium strip having a thickness of 10-250 μm is used. The material is used as the raw material, and the lithium metal strip is rolled and compounded on the stress control layer of the bearing layer with the stress control layer by rolling, so as to obtain the ultra-thin lithium film compound.
The method according to claim 8, wherein the rolling pressure range is 0.1-150Mpa, preferably 80-120Mpa.
The method according to claim 8, wherein the rolling is cold rolling, hot rolling or composite rolling, wherein the temperature range of the hot rolling is 60-120°C, and the composite rolling is preferably hot rolling and then cold rolling.