Viscous fluid slurry and method of making and use thereof

Abstract

The present application relates to the technical field of lithium ion battery negative electrode lithium supplement, in particular to a viscous fluid slurry, a preparation method and application thereof. The raw materials of the viscous fluid slurry include: granular graphite, electronic conductive agent and oil-like substance; wherein the weight ratio of the granular graphite and the electronic conductive agent is 1:(0.01-1), and the weight ratio of the total weight of the granular graphite and the electronic conductive agent and the weight of the oil-like substance is (0.05-0.75):1. When the viscous fluid slurry is used for auxiliary manufacturing of lithium-containing metal strip, the granular graphite can effectively improve the friction between the roller surface and the surface of the lithium-containing metal strip, so that the metal lithium or lithium alloy is more easily rolled out to be an ultra-thin metal lithium with uniform thickness in the differential speed rolling process; when the lithium ion battery negative electrode is supplemented with lithium, the electronic conductive agent can build a complete and continuous electronic path between the negative electrode and the lithium-containing metal strip, so as to avoid the generation of dead lithium, and further improve the utilization rate of the metal lithium or lithium alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion battery negative electrode lithium supplement, and particularly relates to a viscous fluid slurry, a preparation method and application thereof. BACKGROUND

[0002] Among the many methods of lithium ion battery negative electrode lithium supplement, the lithium metal belt pressure extension lithium supplement has the advantages of high efficiency, high safety and low cost. In this method, the performance of the lithium metal belt has a significant impact on the lithium supplement effect.

[0003] In related technologies, when manufacturing the lithium metal belt, a lubricant such as an oil-like substance is usually applied to the surface of the roller or the surface of the lithium metal belt, and then the metal lithium or lithium alloy is rolled. However, in the process of implementing the present application, the inventors found that the thickness of the lithium metal belt prepared by this method fluctuates greatly, and when used for lithium ion battery negative electrode lithium supplement, it will produce dead lithium phenomenon. SUMMARY

[0004] The inventors found that the reason for the above problems in the lithium metal belt prepared in related technologies is that: (1) when an oil-like substance is used as a lubricant, the oil-like substance has good lubricity, and there is almost no friction between the surface of the roller and the surface of the lithium metal belt. During the rolling process, the lithium metal belt is prone to deviation, which leads to a large thickness fluctuation of the prepared lithium metal belt; (2) during the lithium supplement process, the oil-like substance will exist between the negative electrode and the lithium metal belt, resulting in the absence of an electronic conduction network between the negative electrode and the lithium metal belt. Part of the metal lithium or alloy lithium cannot be fully utilized, resulting in dead lithium phenomenon.

[0005] Therefore, the present application provides a viscous fluid slurry, a preparation method and application thereof. The viscous fluid slurry can be used to assist in manufacturing a lithium metal belt to solve the problem of large thickness fluctuation of the lithium metal belt prepared in related technologies, which will produce dead lithium phenomenon when used for lithium ion battery negative electrode lithium supplement.

[0006] In a first aspect, the present application provides a viscous fluid slurry, the raw materials of the viscous fluid slurry comprising:

[0007] Granular graphite, electronic conductive agent and oil-like substance;

[0008] The weight ratio of the granular graphite to the electronic conductive agent is 1:(0.01-1), and the weight ratio of the total weight of the granular graphite and the electronic conductive agent to the weight of the oil-like substance is (0.05-0.75):1.

[0009] In the viscous fluid slurry provided by the present application, in addition to containing the oil-like substance, the viscous fluid slurry also contains particulate graphite and an electronic conductive agent. When the viscous fluid slurry is used to assist in manufacturing a lithium-containing metal strip, the particulate graphite can effectively increase the friction between the surface of the roller and the surface of the lithium-containing metal strip, and the increase in the friction can make the metal lithium or lithium alloy more easily rolled into an ultra-thin lithium-containing metal strip with uniform thickness during differential speed rolling, and can improve or eliminate the deviation of the lithium-containing metal strip; when performing lithium supplement for the negative electrode of a lithium ion battery, the electronic conductive agent can build a complete and continuous electronic path between the negative electrode and the lithium-containing metal strip, and the presence of the electronic path can avoid the generation of dead lithium due to the disconnection of the electronic path during the lithium supplement process, thereby improving the utilization rate of the metal lithium or lithium alloy, and at the same time, the reduction or elimination of the dead lithium is also conducive to improving the safety of the lithium ion battery.

[0010] In an alternative embodiment, the particulate graphite includes at least one of coal-based artificial graphite, petroleum-based artificial graphite, spherical flake natural graphite, and earthy natural graphite.

[0011] And / or, the electronic conductive agent includes at least one of single-walled carbon nanotubes, vapor-grown carbon fibers, multi-walled carbon nanotubes, conductive carbon black, and graphene.

[0012] And / or, the oil-like substance includes at least one of lubricating oil, white mineral oil, paraffin oil, heat-conducting oil, machine oil, silicone oil, anti-rust oil, hydraulic oil, and cutting fluid.

[0013] In an alternative embodiment, the particle size D50 of the particulate graphite is 0.05 μm to 50 μm.

[0014] In an alternative embodiment, the raw material of the viscous fluid slurry further includes:

[0015] at least one of a free radical initiator, a polyhydroxy compound, and a bridging agent;

[0016] wherein the weight ratio of the polyhydroxy compound to the bridging agent is (1-10):(10-1), the weight ratio of the free radical initiator to the total weight of the polyhydroxy compound and the bridging agent is (0.5-35):100, and the total weight of the free radical initiator, the polyhydroxy compound, and the bridging agent to the weight of the oil-like substance is (0.002-0.15):1.

[0017] In the aforementioned viscous fluid slurry, the addition of free radical initiators, polyhydroxy compounds, and crosslinking agents can solidify the electronic conductive agent between the negative electrode and the lithium-containing metal strip, thereby improving the connection stability between the electronic conductive agent and the negative electrode and the lithium-containing metal strip. This can further enhance the integrity and stability of the electronic pathway constructed by the electronic conductive agent, thereby further reducing the amount of dead lithium generated and further improving the utilization rate of metallic lithium or lithium alloys.

[0018] In one optional embodiment, the free radical initiator includes at least one of organic peroxide initiators, inorganic peroxide initiators, azo initiators, and redox initiators.

[0019] For example, organic peroxide initiators may include at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoyl peroxide, tert-butyl hydroperoxide, and cyclohexanone peroxide; inorganic peroxide initiators may include at least one of sodium persulfate and ammonium persulfate; azo initiators may include at least one of azobisisoheptanenitrile and azobisisobutyronitrile; and redox initiators may include at least one of cumene hydroperoxide / tetraethyleneimine, benzoyl peroxide / N,N-dimethylaniline, and hydroperoxide / tartaric acid.

[0020] And / or, the polyhydroxy compound includes at least one of vinylene carbonate, fluoroethylene carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate.

[0021] And / or, the crosslinking agent comprises at least one of triethylene glycol dimethacrylate, ethyl-4-methylimidazole, 2-phenylimidazole, triethylene glycol dimethacrylate, tetrachlorophthalic anhydride, hexahydrophthalic anhydride, triethylenetetramine, and dimethylaminopropylamine.

[0022] In one optional embodiment, the viscosity of the viscous fluid slurry at 25°C is 8000 mPa·s to 450000 mPa·s;

[0023] And / or, the areal density of the viscous fluid slurry is 3 mg / cm³. 2 ~100mg / cm 2 .

[0024] In the above embodiments, the viscous fluid slurry has a suitable viscosity, which is beneficial to ensuring the uniformity of the viscous fluid slurry coating on the lithium-containing metal strip surface, and this helps to further improve the thickness uniformity of the lithium-containing metal strip. Specifically, within the above viscosity range, the stability of the slurry film formed by the viscous fluid slurry on the lithium-containing metal strip surface can be effectively ensured, avoiding a significant change in the areal density of the viscous fluid slurry on the lithium-containing metal strip surface in a short period of time due to excessively low viscosity; at the same time, it can also effectively ensure that the viscous fluid slurry spreads smoothly on the lithium-containing metal strip surface, avoiding the formation of obvious groove-like structures on the lithium-containing metal strip surface due to excessively high viscosity.

[0025] Secondly, the present invention also provides a method for preparing the above-mentioned viscous fluid slurry, comprising the following steps:

[0026] The granular graphite, the electronically conductive agent, and the oil-like substance are mixed, stirred, and allowed to stand.

[0027] In one optional embodiment, the stirring conditions include: a stirring speed of 200 rpm to 5000 rpm, a temperature of 0°C to 60°C, and a stirring time of 0.5 h to 9 h.

[0028] And / or, the conditions for settling include: settling in a vacuum environment of -98 kPa to -35 kPa for 1 h to 6 h.

[0029] In one optional embodiment, after the settling period, the preparation method further includes the steps of adding the free radical initiator, the polyhydroxy compound, and the crosslinking agent and then curing them.

[0030] In the above preparation method, the curing method is determined by the type of free radical initiator, usually by thermal initiation or photoinitiation. The material obtained after initiation and curing is a gel-like substance with good adaptability in batteries. In actual production, curing can be initiated by setting a curing device after the calendering roll. The curing device can be set only on one side of the lithium metal strip coated with the viscous fluid slurry, or it can be set on both sides of the lithium metal strip to make the curing reaction faster and more uniform.

[0031] Thirdly, the present invention also provides the use of the above-mentioned viscous fluid slurry in the manufacture of lithium-containing metal strips, the lithium-containing metal strips including lithium metal strips and lithium alloy strips.

[0032] The lithium metal strip refers to a pure lithium strip, and the lithium alloy strip refers to a metal strip that contains other metals such as sodium, magnesium, aluminum, and calcium in addition to lithium. Detailed Implementation

[0033] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0034] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0035] The present invention will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed by the present invention.

[0036] In the following embodiments of the present invention, the coal-based artificial graphite used was purchased from Qingdao Tianheda Graphite Co., Ltd. and Shijiazhuang Fengming Mineral Products Co., Ltd., and the model number was SQ-65; the petroleum-based artificial graphite was purchased from Nanyang Jinping Mining Co., Ltd. and Henan Liugong Graphite Co., Ltd., and the model number was NH-4-M; the spherical flake natural graphite was purchased from Lingshou County Quanfeng Mineral Products Processing Plant and Hebei Jiegui Mineral Products Co., Ltd., and the model number was LB-3; and the earthy natural graphite was purchased from Yixing Qiankun Carbon Products Co., Ltd. and Henan Liugong Graphite Co., Ltd., and the model number was YG-002.

[0037] In the following embodiments or comparative examples of the present invention, when measuring the change in surface density of the viscous fluid slurry on the surface of the lithium metal strip before and after calendering, a 40cm long lithium metal strip is taken 120 minutes after the start of calendering, and the change in surface density of the viscous fluid slurry on its surface is measured; when measuring the offset of the lithium metal strip, the measurement is performed 120 minutes after the start of calendering; when measuring the thickness of the ultra-thin lithium metal strip, the ultra-thin lithium metal strip is divided into three columns: left, middle, and right, with one point taken every 10cm in each column, and 10 points taken in each column, and the thickness variance at all points is calculated; when measuring the amount of dead lithium after lithium intercalation, the strip is divided into three columns: left, middle, and right, with a 3cm*3cm area taken every 25cm in each column, and 10 areas taken in each column to measure the amount of dead lithium, and the average value is calculated.

[0038] Example 1

[0039] Prepare viscous fluid slurry according to the following method:

[0040] Take 70g of petroleum-based artificial graphite with a particle size D50 of 10μm, 30g of multi-walled carbon nanotubes with a length of 20±3μm, and 150g of white mineral oil. Stir at 1500rpm (linear velocity 7.5m / s) in an environment of 25℃ for 3.5h under the action of cooling water. After stirring, let it stand in a vacuum environment of -95kPa for 1.5h to obtain viscous fluid slurry A.

[0041] In this embodiment, the weight ratio of granular graphite (petroleum-based artificial graphite) to electronically conductive agent (multi-walled carbon nanotubes) is 1:0.43, and the weight ratio of the total weight of granular graphite (petroleum-based artificial graphite) and electronically conductive agent (multi-walled carbon nanotubes) to the weight of oil-like substance (white mineral oil) is 0.67:1. The viscosity of the viscous fluid slurry A prepared in this embodiment was tested, and the result was 10500 mPa·s.

[0042] The viscous fluid slurry A prepared in this embodiment was used at 5.7 mg / cm³. 2 The areal density of the lithium metal slurry was coated onto the surface of a 2200 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 8 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0043] Example 2

[0044] Viscous fluid slurry B was prepared according to the method of Example 1, except that in this example, 40g of graphene with an average number of no more than 5 layers was used to replace 30g of multi-walled carbon nanotubes in Example 1.

[0045] In this embodiment, the weight ratio of granular graphite (petroleum-based artificial graphite) to electronically conductive agent (graphene) is 1:0.57, and the weight ratio of the total weight of granular graphite (petroleum-based artificial graphite) and electronically conductive agent (graphene) to the weight of oil-like substance (white mineral oil) is 0.73:1.

[0046] The viscosity of the viscous fluid slurry B prepared in this embodiment was tested, and the result was 12600 mPa·s.

[0047] The viscous fluid slurry B prepared in this embodiment was used at 6.5 mg / cm³. 2The areal density of the lithium metal slurry was coated onto the surface of a 3700 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 15 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0048] Example 3

[0049] Prepare viscous fluid slurry according to the following method:

[0050] Take 85g of petroleum-based artificial graphite with a particle size D50 of 10μm, 20g of conductive carbon black with a particle size not exceeding 1μm, and 470g of polydimethylsiloxane. Stir at a stirring speed of 1500rpm (linear speed 7.5m / s) in an environment of 25℃ for 3.5h under the action of cooling water. After stirring, let it stand for 1.5h in a vacuum environment of -95kPa to obtain viscous fluid slurry C.

[0051] In this embodiment, the weight ratio of granular graphite (petroleum-based artificial graphite) to electronically conductive agent (conductive carbon black) is 1:0.24, and the weight ratio of the total weight of granular graphite (petroleum-based artificial graphite) and electronically conductive agent (conductive carbon black) to the weight of oil-like substance (polydimethylsiloxane) is 0.22:1. The viscosity of the viscous fluid slurry C prepared in this embodiment was tested, and the result was 27700 mPa·s.

[0052] The viscous fluid slurry C prepared in this embodiment was used at a concentration of 13.2 mg / cm³. 2 The areal density of the lithium metal slurry was coated onto the surface of a 3100 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 4 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0053] Example 4

[0054] Viscous fluid slurry D was prepared according to the method of Example 1, except that 65g of single-walled carbon nanotubes with a length of 1200μm were used in this example to replace the 30g of multi-walled carbon nanotubes in Example 1.

[0055] In this embodiment, the weight ratio of granular graphite (petroleum-based artificial graphite) to electronically conductive agent (single-walled carbon nanotubes) is 1:0.93, and the weight ratio of the total weight of granular graphite (petroleum-based artificial graphite) and electronically conductive agent (single-walled carbon nanotubes) to the weight of oil-like substance (white mineral oil) is 0.90:1. The viscosity of the viscous fluid slurry D prepared in this embodiment was tested, and the result was 290,000 mPa·s.

[0056] The viscous fluid slurry D prepared in this embodiment was used at 8.2 mg / cm³. 2 The areal density of the lithium metal slurry was coated onto the surface of a 3400 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 9 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0057] Example 5

[0058] Viscous fluid slurry E was prepared according to the method of Example 1, except that in this example, 30g of vapor-grown carbon fibers with a length of 105μm were used instead of 30g of multi-walled carbon nanotubes in Example 1.

[0059] In this embodiment, the weight ratio of granular graphite (petroleum-based artificial graphite) to electronically conductive agent (vapor-grown carbon fiber) is 1:0.43, and the weight ratio of the total weight of granular graphite (petroleum-based artificial graphite) and electronically conductive agent (vapor-grown carbon fiber) to the weight of oil-like substance (white mineral oil) is 0.67:1. The viscosity of the viscous fluid slurry E prepared in this embodiment was tested, and the result was 15000 mPa·s.

[0060] The viscous fluid slurry E prepared in this embodiment was used at 17 mg / cm³. 2 The areal density of the lithium metal slurry was coated onto the surface of a 3500 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 37 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0061] Example 6

[0062] The viscous fluid slurry F is prepared according to the following method:

[0063] Take the viscous fluid slurry A prepared in Example 1, add 3g of polyhydroxy compound (ethylene carbonate), 4g of crosslinking agent (triethylene glycol dimethacrylate), and 0.06g of thermal initiator (azobisisobutyronitrile), and stir for 2h at 350rpm (linear speed 1.75m / min) in an environment of 25°C to obtain viscous fluid slurry F.

[0064] In this embodiment, the weight ratio of the polyhydroxy compound to the crosslinking agent is 3:4, the weight ratio of the free radical initiator to the total weight of the polyhydroxy compound and the crosslinking agent is 0.86:100, and the weight ratio of the total weight of the free radical initiator, the polyhydroxy compound, and the crosslinking agent to the weight of the oil-like substance is 0.047:1.

[0065] The viscosity of the viscous fluid slurry F prepared in this embodiment was tested, and the result was 10800 mPa·s.

[0066] The viscous fluid slurry F prepared in this embodiment was used at a concentration of 17.7 mg / cm³. 2 The areal density of the slurry was coated onto the surface of a 2800 μm thick lithium metal strip to be rolled, and cured at 65°C. The lithium metal was then rolled to produce an ultrathin lithium metal strip with a target thickness of 10 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. Furthermore, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after intercalation was tested and calculated. The test and calculation results are shown in Table 1.

[0067] Example 7

[0068] Viscous fluid slurry G was prepared according to the method of Example 1, except that in this example, an equal amount of earthy natural graphite with a particle size D50 of 10 μm was used to replace the petroleum-based artificial graphite in Example 1.

[0069] The viscosity of the viscous fluid slurry G prepared in this embodiment was tested, and the result was 10500 mPa·s.

[0070] The viscous fluid slurry G prepared in this embodiment was used at 5.7 mg / cm³. 2 The areal density of the lithium metal slurry was coated onto the surface of a 2200 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 13 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0071] Example 8

[0072] Viscous fluid slurry H was prepared according to the method of Example 1, except that in this example, an equal amount of coal-based artificial graphite with a particle size D50 of 10 μm was used to replace the petroleum-based artificial graphite in Example 1.

[0073] The viscosity of the viscous fluid slurry H prepared in this embodiment was tested, and the result was 15300 mPa·s.

[0074] The viscous fluid slurry H prepared in this embodiment was used at 5.7 mg / cm³. 2 The areal density of the lithium metal slurry was coated onto the surface of a 2200 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 11 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0075] Example 9

[0076] Viscous fluid slurry I was prepared according to the method of Example 1, except that in this example, an equal amount of spherical flake natural graphite with a particle size D50 of 10 μm was used to replace the petroleum-based artificial graphite in Example 1.

[0077] The viscosity of the viscous fluid slurry I prepared in this embodiment was tested, and the result was 17700 mPa·s.

[0078] The viscous fluid slurry I prepared in this embodiment was used at 5.7 mg / cm³. 2 The areal density of the lithium metal slurry was coated onto the surface of a 2200 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 11 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0079] Example 10

[0080] Viscous fluid slurry J is prepared according to the following method:

[0081] Take the viscous fluid slurry G prepared in Example 7, add 3g of polyhydroxy compound (fluoroethylene carbonate), 4g of crosslinking agent (triethylene glycol dimethacrylate), and 0.11g of photoinitiator (2-hydroxy-2-methyl-1-phenyl-1-propanone), and stir at 350rpm (linear speed 1.75m / min) for 2h in an environment of 25°C to obtain viscous fluid slurry J.

[0082] In this embodiment, the weight ratio of the polyhydroxy compound to the crosslinking agent is 3:4, the weight ratio of the free radical initiator to the total weight of the polyhydroxy compound and the crosslinking agent is 1.57:100, and the weight ratio of the total weight of the free radical initiator, the polyhydroxy compound, and the crosslinking agent to the weight of the oil-like substance is 0.047:1.

[0083] The viscosity of the viscous fluid slurry J prepared in this embodiment was tested, and the result was 11500 mPa·s.

[0084] The viscous fluid slurry J prepared in this embodiment was used at 15.9 mg / cm³. 2 The areal density of the slurry was coated onto the surface of a 2500 μm thick lithium metal strip to be rolled. Photocuring was performed at a wavelength of 400 nm, followed by lithium metal rolling to produce an ultrathin lithium metal strip with a target thickness of 7 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. Furthermore, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after intercalation was tested and calculated. The test and calculation results are shown in Table 1.

[0085] Example 11

[0086] The viscous fluid slurry K was prepared according to the method of Example 1, except that 0.7g of the same type of carbon nanotubes was used to replace 30g of carbon nanotubes in Example 1, and 1414g of the same type of white mineral oil was used to replace 150g of white mineral oil in Example 1.

[0087] In this embodiment, the weight ratio of granular graphite (petroleum-based artificial graphite) to electronically conductive agent (multi-walled carbon nanotubes) is 1:0.01, and the weight ratio of the total weight of granular graphite (petroleum-based artificial graphite) and electronically conductive agent (multi-walled carbon nanotubes) to the weight of oil-like substance (white mineral oil) is 0.05:1. The viscosity of the viscous fluid slurry K prepared in this embodiment was tested, and the result was 22100 mPa·s.

[0088] The viscous fluid slurry K prepared in this embodiment was used at 5.7 mg / cm³. 2The areal density of the lithium metal slurry was coated onto the surface of a 2200 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 10 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0089] Comparative Example 1

[0090] Silicone oil at 5.7 mg / cm 2 The areal density of the lithium metal slurry was coated onto the surface of a 2200 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 10 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0091] Comparative Example 2

[0092] White mineral oil at 5.7 mg / cm³ 2 The areal density of the lithium metal slurry was coated onto the surface of a 2200 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 12 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0093] Comparative Example 3

[0094] Prepare viscous fluid slurry according to the following method:

[0095] Take 30g of multi-walled carbon nanotubes with a length of 20±3μm and 150g of white mineral oil. Stir at 1500rpm (linear speed 7.5m / s) in an environment of 25℃ for 3.5h under the action of cooling water. After stirring, let it stand in a vacuum environment of -95kPa for 1.5h to obtain viscous fluid slurry D3.

[0096] The viscosity of the viscous fluid slurry D3 prepared in this comparative example was tested, and the result was 18500 mPa·s.

[0097] The viscous fluid slurry D3 prepared in this comparative example was used at 5.7 mg / cm³.2 The areal density of the lithium metal slurry was coated onto the surface of a 2200 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 8 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0098] Comparative Example 4

[0099] Prepare viscous fluid slurry according to the following method:

[0100] Take 70g of petroleum-based artificial graphite with a particle size D50 of 10μm and 150g of white mineral oil. Stir at a stirring speed of 1500rpm (linear velocity 7.5m / s) in an environment of 25℃ for 3.5h under the action of cooling water. After stirring, let it stand in a vacuum environment of -95kPa for 1.5h to obtain viscous fluid slurry D4.

[0101] The viscosity of the viscous fluid slurry D4 prepared in this comparative example was tested, and the result was 13300 mPa·s.

[0102] The viscous fluid slurry D4 prepared in this comparative example was used at 5.7 mg / cm³. 2 The areal density of the lithium metal slurry was coated onto the surface of a 2200 μm thick lithium metal strip to be rolled, and the lithium metal was rolled to produce an ultrathin lithium metal strip with a target thickness of 8 μm. The change in areal density of the viscous fluid slurry on the surface of the lithium metal strip before and after rolling, the offset of the lithium metal strip, and the thickness variance of the resulting ultrathin lithium metal strip were tested and calculated. In addition, the ultrathin lithium metal strip produced above was transferred to a negative electrode for lithium intercalation, and the percentage of dead lithium after lithium intercalation was tested and calculated. The above test and calculation results are shown in Table 1.

[0103] Table 1. Test and calculation results for each embodiment and comparative example.

[0104]

[0105] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A viscous fluid slurry, characterized in that, The raw materials for the viscous fluid slurry include: Particulate graphite, electronically conductive agents, and oil-like substances; The weight ratio of the granular graphite to the electronically conductive agent is 1:(0.01~1), and the weight ratio of the total weight of the granular graphite and the electronically conductive agent to the weight of the oil-like substance is (0.05~0.75):1; the particle size D50 of the granular graphite is 0.05μm~50μm; the raw materials of the viscous fluid slurry further include at least one of a free radical initiator, a polyhydroxy compound, and a crosslinking agent; Wherein, the weight ratio of the polyhydroxy compound to the crosslinking agent is (1-10):(10-1), the weight ratio of the free radical initiator to the total weight of the polyhydroxy compound and the crosslinking agent is (0.5-35):100, and the weight ratio of the total weight of the free radical initiator, the polyhydroxy compound, and the crosslinking agent to the weight of the oil-like substance is (0.002-0.15):1; The viscosity of the viscous fluid slurry at 25°C is 8000 mPa·s to 450000 mPa·s. The electronically conductive agent includes at least one of single-walled carbon nanotubes, vapor-grown carbon fibers, multi-walled carbon nanotubes, conductive carbon black, and graphene. The oil-like substances include at least one of the following: lubricating oil, white mineral oil, paraffin oil, heat transfer oil, silicone oil, rust-preventive oil, and hydraulic oil; The polyhydroxy compound includes at least one of vinylene carbonate, fluoroethylene carbonate, ethylene carbonate, and propylene carbonate. The crosslinking agent includes at least one of trihexyethylene glycol dimethacrylate and triethylene glycol dimethacrylate.

2. The viscous fluid slurry according to claim 1, characterized in that, The granular graphite includes at least one of coal-based artificial graphite, petroleum-based artificial graphite, spherical flake natural graphite, and earthy natural graphite.

3. The viscous fluid slurry according to claim 1, characterized in that, The free radical initiator includes at least one of organic peroxide initiators, inorganic peroxide initiators, azo initiators, and redox initiators.

4. The viscous fluid slurry according to any one of claims 1 to 3, characterized in that, The surface density of the viscous fluid slurry is 3 mg / cm³. 2 ~100 mg / cm 2 .

5. The method for preparing the viscous fluid slurry according to any one of claims 1 to 4, characterized in that, Includes the following steps: The granular graphite, the electronically conductive agent, and the oil-like substance are mixed, stirred, and allowed to stand.

6. The preparation method according to claim 5, characterized in that, The stirring conditions include: stirring speed of 200 rpm to 5000 rpm, temperature of 0℃ to 60℃, and stirring time of 0.5 h to 9 h. And / or, the conditions for settling include: settling in a vacuum environment of -98 kPa to -35 kPa for 1 h to 6 h.

7. The preparation method according to claim 5 or 6, characterized in that, After the settling period, the preparation method further includes the steps of adding the free radical initiator, the polyhydroxy compound, and the crosslinking agent and then curing them.

8. Use of the viscous fluid slurry according to any one of claims 1 to 4 in the manufacture of lithium-containing metal strips, wherein the lithium-containing metal strips comprise lithium metal strips and lithium alloy strips.

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