CN116936922B

CN116936922B - Solid electrolyte membrane, preparation method thereof and lithium ion battery

Info

Publication number: CN116936922B
Application number: CN202311206937.XA
Authority: CN
Inventors: 张雪; 祁影; 钱云龙
Original assignee: Suzhou Qingtao New Energy S&T Co Ltd
Current assignee: Suzhou Qingtao New Energy S&T Co Ltd
Priority date: 2023-09-19
Filing date: 2023-09-19
Publication date: 2023-12-01
Anticipated expiration: 2043-09-19
Also published as: CN116936922A

Abstract

The application relates to a solid electrolyte membrane, a preparation method thereof and a lithium ion battery. The preparation method of the solid electrolyte membrane comprises the following steps: mixing the halide solid electrolyte powder, a binder and a lubricant to prepare a first mixture; carrying out fibrosis treatment on the first mixture to obtain a second mixture; calendaring the second mixture to obtain a solid electrolyte membrane; the lubricant comprises a first lubricant and a second lubricant, wherein the granularity range of the first lubricant is less than or equal to 15 mu m, and the granularity range of the second lubricant is 30 mu m-80 mu m. The solid electrolyte membrane prepared by the application has excellent uniformity, ductility and mechanical properties.

Description

Solid electrolyte membrane, preparation method thereof and lithium ion battery

Technical Field

The application relates to the technical field of batteries, in particular to a solid electrolyte membrane, a preparation method thereof and a lithium ion battery.

Background

In recent years, as the requirements for the safety performance of lithium ion batteries are increasingly improved, the existing production is mainly to replace liquid electrolyte with solid electrolyte, and the commonly used solid electrolyte is divided into oxide solid electrolyte membrane, sulfide solid electrolyte membrane, polymer solid electrolyte membrane and halide solid electrolyte membrane, wherein the halide solid electrolyte has the advantages of higher ionic conductivity, high oxidation stability, wider chemical window and the like, is often used for preparing the solid electrolyte membrane, is applied between a positive electrode and a negative electrode in the lithium ion battery, is used for separating positive and negative active substances, and avoids the short circuit of the battery.

In the preparation process of an all-solid-state lithium battery adopting a halide solid electrolyte membrane, the film forming process of the halide solid electrolyte membrane is very critical, the electrolyte membrane prepared by directly carrying out mechanical pressing on halide solid electrolyte powder is large in thickness and generally larger than 300 mu m, the film thickness and the uniformity of the membrane are difficult to control, the transmission distance of lithium ions is increased, larger voltage polarization and battery internal resistance are generated, and the electrolyte membrane lacks flexibility and has poor mechanical property. The technology of mixing the halide solid electrolyte powder with the binder still cannot prepare the thin electrolyte membrane with good mechanical properties, the electrochemical properties of the electrolyte membrane are affected by the existence of a large amount of the binder, the existing production technology cannot meet the requirements of the battery on the electrolyte membrane, and the commercialized application of the solid electrolyte membrane is seriously hindered.

Disclosure of Invention

In view of the above, the present application provides a solid electrolyte membrane, a method for preparing the same, and a lithium ion battery. The prepared solid electrolyte membrane has the advantages of thinner thickness, better uniformity, ductility and mechanical property.

The first aspect of the present application provides a method for producing a solid electrolyte membrane, comprising the steps of:

0003. Mixing the halide solid electrolyte powder, a binder and a lubricant to prepare a first mixture;

0003. carrying out fibrosis treatment on the first mixture to obtain a second mixture;

0003. calendaring the second mixture to obtain a solid electrolyte membrane;

0003. the lubricant comprises a first lubricant and a second lubricant, wherein the granularity range of the first lubricant is less than or equal to 15 mu m, and the granularity range of the second lubricant is 30 mu m-80 mu m.

The particle size of the first lubricant is smaller than the particle size of the second lubricant.

In some embodiments, in the lubricant, the mass ratio of the first lubricant to the lubricant is greater than the mass ratio of the second lubricant to the lubricant.

In some preferred embodiments, the mass ratio of the first lubricant to the lubricant is 55% -80%.

In some embodiments, the mass percentages of the halide solid electrolyte powder, the binder, and the lubricant in the first mixture are X, Y and Z, respectively, wherein 80% X is 99.98%; y is more than or equal to 0.01% and less than or equal to 10%; z is more than or equal to 0.01% and less than or equal to 10%.

In some embodiments, the particle size range of the halide solid electrolyte powder is 0.1 μm to 40 μm.

In some preferred embodiments, the particle size difference of the first lubricant and the particle size of the halide solid electrolyte powder ranges from 20% to 150%.

In some more preferred embodiments, the particle size difference of the first lubricant and the particle size of the halide solid electrolyte powder ranges from 40% to 120%.

In some preferred embodiments, the particle size of the second lubricant is greater than the particle size of the halide solid electrolyte powder.

In some embodiments, the first lubricant and the second lubricant are the same substance of different particle sizes.

In some embodiments, the first lubricant and the second lubricant are both hydrous magnesium silicate having the formula Mg ₃ [Si ₄ O ₁₀ ](OH) ₂ 。

In some embodiments, the binder comprises a fiberized binder. Preferably, the fiberizing binder comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride hexafluoropropylene, polypropylene, polyethylene, polyimide; the granularity range of the binder is less than or equal to 38 mu m.

In some embodiments, in the step of preparing the first mixture, the halide solid electrolyte powder, the binder, and the lubricant are mixed by means of ball milling, air flow mixing, or a pulverizer. Preferably, the halide solid electrolyte powder, the binder and the lubricant are mixed by means of a pulverizer.

In some embodiments, in the step of producing the solid electrolyte membrane, the second mixture is subjected to a rolling process by means of rolling and/or flat pressing. Preferably, the second mixture is calendered by means of twin rolls.

In some embodiments, the solid electrolyte membrane has a thickness of 5 μm to 300 μm.

A second aspect of the present application provides a solid electrolyte membrane produced according to the production method provided in the first aspect described above.

A third aspect of the application provides a lithium ion battery comprising the solid electrolyte membrane provided in the second aspect.

According to the application, the first lubricant and the second lubricant with different particle sizes are added into the halide solid electrolyte powder and the binder, so that the prepared solid electrolyte membrane has good uniformity, ductility and mechanical properties. Specifically, the first lubricant has smaller granularity and can be better mixed with the halide solid electrolyte powder, and when in mixing, the first lubricant with small granularity is attached to the surface of the halide solid electrolyte powder, so that the effect of increasing the fluidity between the halide solid electrolyte powder is achieved, the interaction force between the halide electrolyte powder and the binder and between the halide electrolyte powder and the halide electrolyte powder is relieved, and when in calendaring, the electrolyte film can be partially decomposed into horizontal force for shearing and stretching the electrolyte film due to the force of vertical compaction, thereby avoiding hardening and embrittling of the electrolyte film caused by vertical compaction when in calendaring. The second lubricant has larger granularity, and on one hand, the second lubricant can play the role of increasing fluidity as the first lubricant; on the other hand, the second lubricant has certain elasticity, so that the crushing of particles caused by direct extrusion of halide powder in the solid electrolyte membrane can be relieved, the mechanical supporting effect can be achieved, and the problem that the mechanical property of the solid electrolyte membrane is poor due to thin film reduction in the prior art is solved.

Drawings

Fig. 1 is a flow chart of a method for preparing a solid electrolyte membrane according to an embodiment of the application.

Fig. 2 is a schematic view of a solid electrolyte membrane prepared in an embodiment of the present application.

Fig. 3 is a Scanning Electron Microscope (SEM) schematic of a cross section of the solid electrolyte membrane prepared in example 1 of the present application.

Description of the reference numerals

0003.1, halide solid electrolyte powder; 2. a first lubricant; 3. a second lubricant; 4. and (3) a binder.

Detailed Description

Reference now will be made in detail to embodiments of the application, one or more examples of which are described below. Each example is provided by way of explanation, not limitation, of the application. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the scope or spirit of the application. For example, features illustrated or described as part of one embodiment can be used on another embodiment to yield still a further embodiment.

Accordingly, it is intended that the present application cover such modifications and variations as fall within the scope of the appended claims and their equivalents. Other objects, features and aspects of the present application will be disclosed in or be apparent from the following detailed description. It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present application.

In the application, the technical characteristics described in an open mode comprise a closed technical scheme composed of the listed characteristics and also comprise an open technical scheme comprising the listed characteristics.

In the present application, the numerical ranges are referred to as continuous, and include the minimum and maximum values of the ranges, and each value between the minimum and maximum values, unless otherwise specified. Further, when a range refers to an integer, each integer between the minimum and maximum values of the range is included. Further, when multiple range description features or characteristics are provided, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to include any and all subranges subsumed therein.

In this context, referring to units of data range, if a unit is only carried after the right endpoint, the units representing the left and right endpoints are identical. For example, 100 to 150 nm means that the units of the left end point "100" and the right end point "150" are nm (nanometers).

All embodiments of the application and alternative embodiments may be combined with each other to form new solutions, unless otherwise specified.

All technical features and optional technical features of the application may be combined with each other to form new technical solutions, unless specified otherwise.

All the steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise specified. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, it is mentioned that the method may further comprise step (c), meaning that step (c) may be added to the method in any order, e.g. the method may comprise steps (a), (b) and (c), may also comprise steps (a), (c) and (b), may also comprise steps (c), (a) and (b), etc.

The terms "comprising" and "including" as used herein mean open ended or closed ended, unless otherwise noted. For example, the terms "comprising" and "comprises" may mean that other components not listed may be included or included, or that only listed components may be included or included.

The term "or" is inclusive in this application, unless otherwise specified. For example, the phrase "a or B" means "a, B, or both a and B. More specifically, either of the following conditions satisfies the condition "a or B": a is true (or present) and B is false (or absent); a is false (or absent) and B is true (or present); or both A and B are true (or present).

It should be noted that the particle size mentioned in the present application may be represented by conventional methods in the art, such as D50, D90, or other particle size representation, etc., and it is understood that the particle size corresponds to the cumulative particle size distribution of D90, i.e., one sample, up to 90%. The physical meaning is that particles with the particle size smaller than (or larger than) a certain value account for 90%; for example, D90 of the first lubricant is less than or equal to 10 μm, meaning that at least 90% of the particles of the first lubricant have a particle size of less than 10 μm. When comparing the particle sizes of two substances, the same two particle size representations must be used, such as using D50 simultaneously or using D90 simultaneously.

The first aspect of the present application provides a method for preparing a solid electrolyte membrane, as shown in fig. 1, comprising the steps of:

s1: and mixing the halide solid electrolyte powder, the binder and the lubricant to prepare a first mixture.

It will be appreciated that a halide solid electrolyte is a known electrolyte material which is believed to have the advantages of both an oxide solid electrolyte and a sulfide solid electrolyte, which typically can use Li _a MX _b Wherein M is a metal element, which may be a mixture of a plurality of metal elements, which may be the same or different, and X is a halogen element. The structure of metal halide electrolytes depends on their ionic radius and ionic arrangement, and there are three general classes of halide electrolytes commonly used in current research: li (Li) _a MX ₄ 、Li _a MX ₆ Li (lithium ion battery) _a MX ₈ It is to be understood that the present application is not particularly limited in the type of the halide solid electrolyte, and any known halide solid electrolyte can be used in the present application without departing from the spirit of the present application, and the halide solid electrolyte can be LilnCl by way of illustration only and not limitation of the scope of protection ₄ 、Li ₂ CdCl ₄ 、Li ₂ MgCl ₄ 、Li ₂ CdI ₄ 、Li ₂ ZnI ₄ 、Li ₂ ZrCl ₆ And combinations thereof.

Further, the particle size range of the halide solid electrolyte powder is 0.1 μm to 40 μm. Including but not limited to 0.1 μm, 0.2 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, and 40 μm. Preferably, the particle size of the halide solid electrolyte powder ranges from 3 μm to 30 μm. More preferably, the particle size of the halide solid electrolyte powder is in the range of 5 μm to 20 μm.

The binder of the present application includes a fiberizing binder, and it is understood that the fiberizing binder of the present application means that the binder can be converted from a powder state to a fiberized state under the action of a shearing force. Preferably, the fiberizing binder comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride hexafluoropropylene, polypropylene, polyethylene, polyimide.

In other embodiments of the present application, the binder may also include a non-fibrous binder, which may be, for example, styrene-butadiene rubber, nitrile rubber, sodium hydroxymethyl cellulose, polyacrylic binder, and the like. Generally, the non-fibrous binder has supplementary binding effect on the mixed system, increases the binding property on the halide solid electrolyte powder particles, and improves the mechanical properties of the solid electrolyte membrane.

The granularity range of the binder is less than or equal to 38 mu m. For example, the particle size of the binder may be 38 μm, 35 μm, 32 μm, 28 μm, 25 μm, 20 μm, 15 μm, 10 μm, etc.

The specific surface area of the binder is less than or equal to 40m ² And/g. For example, the binder may have a particle size of 38 m ² /g、35 m ² /g 、32 m ² /g、28 m ² /g、25 m ² /g、20 m ² /g、15 m ² /g、10 m ² /g, etc. Preferably, the specific surface area of the binder is 10 m ² /g ~20 m ² And/g. More preferably, the specific surface area of the binder is 13m ² /g。

The lubricant includes a first lubricant and a second lubricant. Wherein the particle size range of the first lubricant is less than or equal to 15 mu m, the particle size range of the second lubricant is 30 mu m-80 mu m, and the particle size of the first lubricant is smaller than the particle size of the second lubricant.

It is understood that the present application employs a combination of a first lubricant and a second lubricant having different particle sizes.

In some preferred embodiments, the ratio of the particle size of the first lubricant to the particle size of the halide solid electrolyte powder ranges from 20% to 150%.

In some more preferred embodiments, the ratio of the particle size of the first lubricant to the particle size of the halide solid electrolyte powder ranges from 40% to 120%, the particle size of the first lubricant is close to the particle size of the halide solid electrolyte powder, which is more beneficial to improving the uniformity and mechanical properties of the solid electrolyte membrane, and may be because when the particle sizes of the first lubricant and the halide solid electrolyte powder are the same or similar, the movement speeds and tracks of the first lubricant and the halide solid electrolyte powder are more similar in the mixing process, so that the first lubricant can continuously exist between the particles of the halide solid electrolyte powder, the friction force among the particles is continuously reduced, the flow property of a mixed system consisting of the halide solid electrolyte powder, the binder and the lubricant is improved, the mixing effect is further improved, the uniformity of the distribution of the binder is ensured, and the phenomenon of agglomeration and the like of the halide solid electrolyte powder and the second lubricant is effectively prevented, and the uniformity of the whole prepared solid electrolyte membrane is improved. Meanwhile, the existence of the lubricant can effectively prevent the second mixture from being damaged by the calendaring device when the second mixture is calendared.

In some preferred embodiments, the particle size of the second lubricant is larger than the particle size of the halide solid electrolyte powder, and mainly serves as a supporting binder structure, and improves the mechanical properties of the prepared solid electrolyte membrane.

In some embodiments, the first lubricant and the second lubricant are the same type, including but not limited to aqueous magnesium silicate (Mg ₃ [Si ₄ O ₁₀ ](OH) ₂ ）。

In some embodiments, the mass percentages of the halide solid electrolyte powder, the binder, and the lubricant in the first mixture are X, Y and Z, respectively, wherein 80% X.ltoreq.99.98%; y is more than or equal to 0.01% and less than or equal to 10%; z is more than or equal to 0.01% and less than or equal to 10%, and the sum of X, Y and Z is 1.

In some embodiments, the mass ratio of the first lubricant to the lubricant is greater than the mass ratio of the second lubricant to the lubricant.

In some preferred embodiments, the mass ratio of the first lubricant to the lubricant is 55% to 80%.

The mixing method in the present application is not particularly limited, and any known mixing method can be applied to the present application without departing from the concept of the present application, and is merely illustrative, and not limiting in scope. In the step S1 of preparing the first mixture, the halide solid electrolyte powder, the binder, and the lubricant may be mixed by ball milling, air-flow mixing, or a pulverizer. Preferably, the halide solid electrolyte powder, the binder and the lubricant are mixed by means of a pulverizer.

S2: and carrying out fiberizing treatment on the first mixture to obtain a second mixture.

It will be appreciated that in some embodiments, the halide solid electrolyte powder, binder, lubricant may also be placed directly into the shear force providing device, with the fiberization being completed during continued mixing. In other embodiments, the mixing process and the fiberizing process are accomplished in the same apparatus. Illustratively, the apparatus is a high speed shear.

Under the action of shearing force, the binder is converted into fibers from powder, and the fibers are uniformly distributed among particles of the halide electrolyte powder to form a structure of the binder bridged halide electrolyte powder. The lubricant is uniformly distributed among the halide powder and plays a role in increasing the fluidity of the halide electrolyte powder.

Specifically, the flow energy of the second mixture is 0.5 mJ-400 mJ, preferably 0.5 mJ-300 mJ.

S3: and carrying out calendaring treatment on the second mixture to obtain the solid electrolyte membrane.

According to the application, the second mixture is subjected to calendaring treatment by adopting a rolling device and/or a flat plate extrusion mode, so that the solid electrolyte membrane is prepared. Preferably, the second mixture is calendered by means of twin rolls.

Further, the pair of rollers comprises a first roller piece and a second roller piece which are oppositely arranged, wherein the roller speeds of the first roller piece and the second roller piece can be the same or different. Preferably, the second mixture is calendered by selecting a pair of rolls having different roll speeds of the first roll member and the second roll member. Specifically, the first roller and the second roller each have a roller speed in the range of 0 to 20 r/min, and preferably the speeds are different between the first roller and the second roller. The second mixture is calendared by using the pair roller composed of the first roller piece and the second roller piece with different roller speeds, and the intervals between the halide solid electrolyte powder particles in the mixture can be supplemented to a certain extent, so that the uniformity and the film forming property of the solid electrolyte film can be improved.

The temperature of the pair of roll equipment is 50-150 ℃, including but not limited to 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃. Preferably, the temperature of the twin roll apparatus is from 110 ℃ to 130 ℃. More preferably, the temperature of the twin roll apparatus is 120 ℃.

The roll pressing process is not particularly limited, and the roll pressing process, such as the roll pressing pressure, the roll pressing temperature, etc., is adjusted based on the consideration of film forming performance without departing from the spirit of the present application, and is considered to be within the scope of the present application.

Limiting the pressure and temperature of the counter roller device to the above ranges can improve the fusion between the halide electrolyte powder particles, thereby being beneficial to further improving the compactness and continuity of the solid electrolyte membrane.

The thickness of the solid electrolyte membrane prepared by the method is 5-200 mu m.

The area density of the solid electrolyte membrane is in the range of 0.5 mg/cm ² ~30mg/cm ² The porosity is 0.1% -40%.

A second aspect of the present application provides a solid electrolyte membrane produced according to the method for producing a solid electrolyte membrane provided in the first aspect described above.

In some embodiments, the lithium ion battery further comprises a positive electrode plate and a negative electrode plate, wherein a positive electrode tab is led out of the positive electrode plate, and a negative electrode tab is led out of the negative electrode plate.

The positive electrode plate comprises a positive electrode current collector and a positive electrode active electrode material layer formed on the current collector, and the negative electrode plate comprises a negative electrode current collector and a negative electrode active electrode material layer formed on the negative electrode current collector.

The positive electrode active material layer includes a positive electrode active material, a positive electrode binder, and a positive electrode conductive material. The positive electrode active material is a compound capable of reversibly intercalating and deintercalating lithium, and specifically may contain lithium transition metal composite oxides, lithium-containing metal compounds, elemental sulfur, and compounds thereof.

Preferably, the mass ratio of the positive electrode active material contained in the positive electrode active material layer may be 80wt% to 99wt%, such as 80wt%, 82wt%, 85wt%, 87wt%, 90wt%, 92wt%, 95wt%, 97wt%, 99wt%, etc., preferably 92wt% to 98.5wt%.

The positive electrode binder is used to bind together components such as a positive electrode active material, a positive electrode conductive material, and a positive electrode current collector, and specifically, the positive electrode binder may contain at least one selected from polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, styrene-butadiene rubber, and fluororubber, and is preferably polyvinylidene fluoride.

The mass ratio of the positive electrode binder contained in the positive electrode active electrode material layer may be 1wt% to 20wt%, such as 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, etc., and is preferably 1.2wt% to 10wt%.

The positive electrode conductive material is mainly used to assist and improve conductivity in the secondary battery, and is not particularly limited in the embodiment of the present application as long as it has conductivity without causing chemical changes. Specifically, the positive electrode conductive material may contain graphite, such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; conductive tubes, such as carbon nanotubes; metal powders such as fluorocarbon powder, aluminum powder, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and a polyphenylene derivative, and the positive electrode conductive material may preferably be carbon black in terms of improving conductivity.

The specific surface area of the positive electrode conductive material may be 80m ² /g-200 m ² /g, preferably 100 m ² /g-150 m ² /g。

The mass ratio of the positive electrode conductive material contained in the positive electrode active electrode material layer may be 1wt% to 20wt%, for example, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, etc., and is preferably 1.2wt% to 10wt%.

The thickness of the positive electrode active electrode material layer may be 30 μm to 400 μm, for example, 30 μm, 40 μm, 50 μm, 80 μm, 110 μm, 200 μm, 300 μm, 400 μm, preferably 50 μm to 110 μm.

The positive electrode sheet may be manufactured by coating a positive electrode slurry including a solvent and a positive electrode active material and/or a positive electrode binder, a positive electrode conductive material dissolved in the solvent on a positive electrode current collector, followed by drying and rolling.

The solvent may contain an organic solvent such as N-methyl-2-pyrrolidone (NMP), and may be used in such an amount that a preferable viscosity is obtained when a positive electrode active material is contained and a positive electrode binder, a positive electrode conductive material, or the like is optionally contained. For example, the amount of the solvent contained in the positive electrode slurry may be such that the concentration of the solid containing the positive electrode active material and optionally containing the positive electrode binder and the positive electrode conductive material is 50wt% to 95wt%, preferably 70wt% to 90wt%.

The negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer formed on the surface of the negative electrode current collector, wherein the negative electrode active material layer at least comprises a negative electrode active material and a negative electrode binder.

The anode active material in the embodiment of the present application is not particularly limited as long as it is a substance capable of electrochemically occluding and releasing s-region metal ions such as lithium ions, sodium ions, potassium ions, magnesium ions, and the like, and for example, carbonaceous materials, metal compound-based materials, or oxides, carbides, nitrides, silicides, sulfides, phosphides, and the like thereof may be used alone, or two or more kinds thereof may be used in combination at random.

In some embodiments, a carbon material may be selected as the anode active material, and in particular, one or more of the following may be selected: graphite, needle coke, amorphous carbon, carbon-containing mesophase, carbon fiber, and carbon material with a small graphitization degree. Wherein the graphite may include natural graphite, artificial graphite, and the like. In addition, a material obtained by coating them with a carbon material, for example, amorphous carbon or graphitized material may be used. Amorphous carbon includes, but is not limited to, particles obtained by firing the bulk mesophase, particles obtained by subjecting a carbon precursor to non-melting treatment and firing. Examples of carbonaceous particles having a small graphitization degree include particles obtained by firing an organic material at a temperature of usually less than 2500 ℃.

In addition, the nonmetallic materials which can be used as the anode active material also comprise simple substances of silicon, compounds thereof and the like, such as Si and SiOx (x is more than or equal to 0 and less than 2), and the silicon-containing materials are easy to expand and fall off from the anode current collector and have poor conductivity, so the nonmetallic materials are often mixed with carbon materials, such as a core-shell structure containing a carbon coating layer and the like.

In some embodiments, a metal simple substance and a metal compound may be selected as the anode active material, for example, a compound containing a metal or metalloid such as Li, ag, al, bi, cu, ga, ge, in, ni, pb, sb, si, sn, sr, zn.

The mass ratio of the anode active material contained in the anode active material layer may be 80 wt% to 99% by weight, for example, 80 wt%, 85 wt%, 90 wt%, 95wt%, 97wt%, 99% by weight, or the like, preferably 95% to 97% by weight.

When the anode active material is a nonmetallic material such as a carbon material, the anode binder may be one or more of aqueous binders such as sodium hydroxymethylcellulose, styrene-butadiene latex, polyacrylic acid, acrylic copolymers, cyclodextrin, etc.;

0003. the anode active material layer may be obtained by coating an anode slurry including at least an anode active material and an anode binder on an anode current collector, followed by drying, and the like. When an aqueous solvent is used as a liquid medium for forming the negative electrode slurry, it is preferable to slurry using a tackifier, which is generally used to adjust the viscosity of the slurry.

The tackifier in the embodiment of the application can be one or more of the following: carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, salts thereof, and the like.

The mass ratio of the thickener in the anode slurry may be 0.1wt% to 5wt%, for example, 0.1wt%, 0.2wt%, 0.5wt%, 0.6wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, etc., preferably 0.5wt% to 3wt%, further preferably 0.6wt% to 2wt%.

In the embodiment of the present application, the positive electrode active material layer and/or the negative electrode active material layer may be formed by dry pressing without using a binder, and the positive electrode active material layer and/or the negative electrode active material layer may be set by a user according to actual needs without limitation.

The present application will be further described with reference to specific examples and comparative examples.

Example 1

Weighing the materials according to the total mass of the first mixture of 50g, wherein the mass percentages of the halide solid electrolyte powder, the binder and the lubricant are respectively 99%, 0.8% and 0.2%, and weighing the LilnCl ₄ The powder, the bonding agent PTFE, the magnesium silicate with water contained in the first lubricant and the magnesium silicate with water contained in the second lubricant are mixed by a jet mill to prepare a first mixture. Wherein LilnCl ₄ The granularity of the powder is 12 mu m, and the conductivity is 11x10 ^-4 S/cm. Apparent particle size of binder<7.2 μm and a specific surface area of 13m ² And/g. The particle size of the first lubrication is 10 μm; the particle size of the second lubricant was 40 μm.

And shearing the first mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain a second mixture, wherein the flow energy of the second mixture is 78mJ.

And (3) rolling and forming the second mixture on a pair-roller device with the temperature of 120 ℃ and the roller speed of the first roller piece of 5 r/min and the roller speed of 20 r/min. A solid electrolyte membrane as shown in fig. 2 was prepared.

The solid electrolyte membrane prepared in this example had a thickness of 38. Mu.m, and an ionic conductivity of 4.08x10 ^-4 S/cm. A schematic of Scanning Electron Microscopy (SEM) of a cross section of a solid electrolyte membrane is shown in fig. 3.

Example 2

Weighing the materials according to the total mass of the first mixture of 50g, wherein the mass percentages of the halide solid electrolyte powder, the binder and the lubricant are respectively 99%, 0.8% and 0.2%, and weighing the LilnCl ₄ Powder, a bonding agent PTFE, a first lubricant containing water-containing magnesium silicate,The second lubricant, hydrous magnesium silicate, is mixed by a jet mill to produce a first mixture. Wherein LilnCl ₄ The granularity of the powder is 12 mu m, and the conductivity is 11x10 ^-4 S/cm. Apparent particle size of binder<7.2 μm and a specific surface area of 13m ² And/g. The particle size of the first lubrication was 14 μm; the particle size of the second lubricant was 40 μm.

And shearing the first mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain a second mixture, wherein the flow energy of the second mixture is 86mJ.

The second mixture was roll-formed on a twin-roll apparatus having a temperature of 120℃and a roll speed of 5 r/min for the first roll and a roll speed of 20 r/min for the second roll, to prepare a solid electrolyte membrane as shown in FIG. 2.

The solid electrolyte membrane prepared in this example had a thickness of 42. Mu.m, and an ionic conductivity of 3.86x10 ^-4 S/cm。

Example 3

Weighing the materials according to the total mass of the first mixture of 50g, wherein the mass percentages of the halide solid electrolyte powder, the binder and the lubricant are respectively 99%, 0.8% and 0.2%, and weighing the LilnCl ₄ The powder, the bonding agent PTFE, the magnesium silicate with water contained in the first lubricant and the magnesium silicate with water contained in the second lubricant are mixed by a jet mill to prepare a first mixture. Wherein LilnCl ₄ The granularity of the powder is 12 mu m, and the conductivity is 11x10 ^-4 S/cm. Apparent particle size of binder<7.2 μm and a specific surface area of 13m ² And/g. The particle size of the first lubrication is 10 μm; the particle size of the second lubricant was 80 μm.

And shearing the first mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain a second mixture, wherein the flow energy of the second mixture is 263mJ.

The second mixture was roll-formed on a twin-roll apparatus having a temperature of 120℃and a roll speed of 5r/min for the first roll and a roll speed of 40r/min for the second roll, to prepare a solid electrolyte membrane as shown in FIG. 2.

The solid obtained in this exampleThe thickness of the electrolyte membrane was 79 μm and the ionic conductivity was 2.12x10 ^-4 S/cm。

Example 4

Weighing the materials according to the total mass of the first mixture of 50g, wherein the mass percentages of the halide solid electrolyte powder, the binder and the lubricant are respectively 99%, 0.8% and 0.2%, and weighing the LilnCl ₄ The powder, the bonding agent PTFE, the magnesium silicate with water contained in the first lubricant and the magnesium silicate with water contained in the second lubricant are mixed by a jet mill to prepare a first mixture. Wherein LilnCl ₄ The granularity of the powder is 5 mu m, and the conductivity is 11x10 ^-4 S/cm. Apparent particle size of binder<7.2 μm and a specific surface area of 13m ² And/g. The particle size of the first lubrication is 6 μm; the particle size of the second lubricant was 30 μm.

And shearing the first mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain a second mixture, wherein the flow energy of the second mixture is 53mJ.

The solid electrolyte membrane prepared in this example had a thickness of 31. Mu.m, and an ionic conductivity of 4.55x10 ^-4 S/cm。

Example 5

Weighing the materials according to the total mass of the first mixture of 50g, wherein the mass percentages of the halide solid electrolyte powder, the binder and the lubricant are respectively 99%, 0.8% and 0.2%, and weighing the LilnCl ₄ The powder, the bonding agent PTFE, the magnesium silicate with water contained in the first lubricant and the magnesium silicate with water contained in the second lubricant are mixed by a jet mill to prepare a first mixture. Wherein LilnCl ₄ The granularity of the powder is 20 mu m, and the conductivity is 11x10 ^-4 S/cm. Apparent particle size of binder<7.2 μm and a specific surface area of 13m ² And/g. The particle size of the first lubrication is 13 μm; the particle size of the second lubricant was 50 μm.

And shearing the first mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain a second mixture, wherein the flow energy of the second mixture is 305 mJ.

The solid electrolyte membrane prepared in this example had a thickness of 56. Mu.m, and an ionic conductivity of 3.25x10 ^-4 S/cm。

Example 6

Weighing the materials according to the total mass of the first mixture of 50g, wherein the mass percentages of the halide solid electrolyte powder, the binder and the lubricant are respectively 99%, 0.8% and 0.2%, and weighing the LilnCl ₄ The powder, the bonding agent PTFE, the magnesium silicate with water contained in the first lubricant and the magnesium silicate with water contained in the second lubricant are mixed by a jet mill to prepare a first mixture. Wherein LilnCl ₄ The granularity of the powder is 35 mu m, and the conductivity is 11x10 ^-4 S/cm. Apparent particle size of binder<7.2 μm and a specific surface area of 13m ² And/g. The particle size of the first lubrication is 15 μm; the particle size of the second lubricant was 60 μm.

And shearing the first mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain a second mixture, wherein the flow energy of the second mixture is 389mJ.

The solid electrolyte membrane prepared in this example had a thickness of 72. Mu.m, and an ionic conductivity of 2.94x10 ^-4 S/cm。

Example 7

Weighing the materials according to the total mass of the first mixture of 50g, wherein the mass percentages of the halide solid electrolyte powder, the binder and the lubricant are respectively 99%, 0.8% and 0.2%, and weighing the LilnCl ₄ Powder, binder PTFE, first lubricant aqueous magnesium silicate, second lubricant aqueous magnesium silicateThe lubricant, hydrous magnesium silicate, was mixed by a jet mill to produce a first mix. Wherein LilnCl ₄ The granularity of the powder is 15 mu m, and the conductivity is 11x10 ^-4 S/cm. Apparent particle size of binder<7.2 μm and a specific surface area of 13m ² And/g. The particle size of the first lubrication was 9 μm; the particle size of the second lubricant was 70 μm.

And shearing the first mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain a second mixture, wherein the flow energy of the second mixture is 295mJ.

The solid electrolyte membrane prepared in this example had a thickness of 71. Mu.m, and an ionic conductivity of 2.53x10 ^-4 S/cm。

Comparative example 1

Comparative example 1 differs from example 1 only in that no lubricant was added in comparative example 1, and the remainder were the same.

The total mass of the first mixture is 50g, wherein the mass percentages of the halide solid electrolyte powder and the binder are respectively 99% and 1% respectively, and the materials are weighed.

LilnCl is added ₄ Powder and a bonding agent PTFE, and preparing a first mixture through an airflow crushing machine. Wherein LilnCl ₄ The Dv50 of the powder is 12 mu m, and the conductivity is 11x10 ^-4 S/cm. Apparent particle size of binder<7.2 μm, specific surface area 13m ² /g。

And shearing the first mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain a second mixture, wherein the flow energy of the second mixture is 726mJ.

And rolling and forming the second mixture on a pair of roller equipment with the temperature of 120 ℃ and the roller speed of the first roller piece of 5r/min and the roller speed of the second roller piece of 20 r/min.

The solid electrolyte membrane prepared in this comparative example had a thickness of 42. Mu.m, and an ionic conductivity of 3.12x10 ^-4 S/cm。

Comparative example 2

Comparative example 2 differs from example 1 only in that the lubricant of comparative example 1 was the first lubricant alone, and the remainder were the same.

The total mass of the first mixture is 50g, wherein the mass percentages of the halide solid electrolyte powder, the binder and the first lubricant are respectively 99%, 0.8% and 0.2% for weighing.

LilnCl is added ₄ Powder, a bonding agent PTFE, a first lubricant, namely hydrous magnesium silicate, and a first mixture prepared by a jet mill. Wherein LilnCl ₄ The granularity of the powder is 12 mu m, and the conductivity is 11x10 ^-4 S/cm. Apparent particle size of binder<7.2 μm, specific surface area 13m ² And/g. The particle size of the first lubrication was 10 μm.

And shearing the first mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain a second mixture, wherein the flow energy of the second mixture is 74mJ.

And rolling and forming the second mixture on a pair of roller equipment with the temperature of 120 ℃ and the roller speed of the first roller piece of 5r/min and the roller speed of the second roller piece of 20r/min to prepare the solid electrolyte membrane.

The solid electrolyte membrane prepared in this comparative example had a thickness of 39 μm and an ionic conductivity of 3.86×10 ^-4 S/cm。

Comparative example 3

Comparative example 3 differs from example 1 only in that the lubricant of comparative example 3 was selected as the second lubricant only, and the remainder were the same.

The total mass of the first mixture is 50g, wherein the mass percentages of the halide solid electrolyte powder, the binder and the second lubricant are respectively 99%, 0.8% and 0.2% for weighing.

LilnCl is added ₄ The powder, the bonding agent PTFE and the second lubricant aqueous magnesium silicate are prepared into a first mixture through a jet mill. Wherein LilnCl ₄ The granularity of the powder is 12 mu m, and the conductivity is 11x10 ^-4 S/cm. Apparent particle size of binder<7.2 μm, specific surface area 13m ² /g。The particle size of the second lubricant was 40 μm.

And shearing the first mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain a second mixture, wherein the flow energy of the second mixture is 424mJ.

The solid electrolyte membrane prepared in this comparative example had a thickness of 44. Mu.m, and an ion conductivity of 3.54×10 ^-4 S/cm。

Comparative example 4

LilnCl is added ₄ The powder, the bonding agent PTFE and the second lubricant aqueous magnesium silicate are prepared into a first mixture through a jet mill. Wherein LilnCl ₄ The granularity of the powder is 12 mu m, and the conductivity is 11x10 ^-4 S/cm. Apparent particle size of binder<7.2 μm, specific surface area 13m ² And/g. The particle size of the second lubricant was 80 μm.

And shearing the first mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain a second mixture, wherein the flow energy of the second mixture is 513mJ.

The solid electrolyte membrane prepared in this comparative example had a thickness of 76 μm and an ionic conductivity of 2.7x10 ^-4 S/cm。

Test case

(1) Determination of flow energy

The instrument is an FT4 powder rheometer, specifically, the FT4 has a blade with a special designed geometric structure, and when the blade descends to pass through the powder, the resistance applied by the powder to the rotation of the blade is measured. The energy required for the powder to flow is calculated by directly measuring the "work" done by the torque and resistance, which is defined as the flow energy of the powder. The results are shown in Table 1 below.

(2) Determination of ion conductivity

The ionic conductivity of the solid electrolyte membrane was obtained by assembling a symmetrical cell with a steel sheet as the blocking electrode on an electrochemical workstation with an electrochemical impedance spectrum measured at a frequency in the range of 0.1Hz to 7MHz, an amplitude of 10mV, and a temperature of 25 ℃. The results are shown in Table 1 below.

(3) Determination of tensile Strength

Conventional tensile strength measurement methods were employed. The test method is as follows: according to the proportion of the embodiment 1-7 and the comparative example 1-4, a sample conforming to the mechanical property test is prepared, the obtained sample is cut into a strip-shaped sample with the width of 25mm and the length of not less than 75 mm, the initial distance between the clamps is set to be 50+/-5 mm, the two ends of the sample strip are sequentially placed into the upper end and the lower end of the clamp to clamp the clamp, the sample strip and the clamp are ensured to be in the same vertical direction in the process, the sample strip is uniformly stressed and has no obvious tensile deformation, and after preparation, the tensile strength test is performed at the speed of 150+/-10 mm/min. The results are shown in Table 1 below.

From the above experimental data, it is known that, in comparative examples 1 and 2 and comparative example 1, the first lubricant and the second lubricant with different particle sizes are added to the halide solid electrolyte powder and the binder, so that the flow energy of the mixture can be effectively reduced, and the uniformity and mechanical strength of the solid electrolyte membrane can be effectively improved.

In comparative examples 1 and 2, only the first lubricant was added to the halide solid electrolyte powder and the binder, the fluidity of the mixture was greatly increased, and the uniformity and mechanical properties of the resulting solid electrolyte membrane were also improved, but the mechanical properties of the solid electrolyte membrane were improved less effectively than in example 1 by using the first lubricant and the second lubricant having different particle sizes at the same time.

In comparative examples 1 and 3, the mechanical properties of the solid electrolyte membrane were significantly improved by adding only the second lubricant to the halide solid electrolyte powder and the binder, while the fluidity improvement of the mixture was not significantly improved as compared with example 1.

In comparative examples 3 and 4, although the second lubricant was added only to the halide solid electrolyte powder and the binder, it is evident that when the particle size of the second lubricant is smaller, it is more advantageous to increase the fluidity of the mixture, so that the properties of the solid electrolyte membrane are improved.

The application can increase the fluidity of the mixture by adding the lubricant with reasonable design ratio into the halide solid electrolyte powder and the binder, is favorable for preparing the halide solid electrolyte membrane with thinner thickness, uniform thickness and uniform ionic conductivity, and simultaneously, the second lubricant plays a supporting role in the mixture, thereby further improving the mechanical property of the solid electrolyte membrane.

The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The foregoing examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims

1. A method for preparing a solid electrolyte membrane, comprising the steps of:

mixing the halide solid electrolyte powder, a binder and a lubricant to prepare a first mixture;

performing fibrosis treatment on the first mixture to obtain a second mixture;

calendaring the second mixture to obtain a solid electrolyte membrane;

the lubricant comprises a first lubricant and a second lubricant, wherein the granularity range D50 of the first lubricant is less than or equal to 15 mu m, and the granularity range D50 of the second lubricant is 30 mu m-80 mu m.

2. The method for producing a solid electrolyte membrane according to claim 1, wherein in the first mixture, the mass percentages of the halide solid electrolyte powder, the binder, and the lubricant are X, Y and Z, respectively, wherein X is 80% or more and 99.98% or less; y is more than or equal to 0.01% and less than or equal to 10%; z is more than or equal to 0.01% and less than or equal to 10%.

3. The method for producing a solid electrolyte membrane according to claim 1, wherein the particle size of the halide solid electrolyte powder is in the range of 0.1 μm to 40 μm.

4. The method for producing a solid electrolyte membrane according to claim 3, wherein the difference in particle size between the first lubricant and the halide solid electrolyte powder is in the range of 20% to 150%.

5. The method for producing a solid electrolyte membrane according to claim 1, wherein the binder comprises a fibrous binder comprising one or more of polytetrafluoroethylene, polyvinylidene fluoride hexafluoropropylene, polypropylene, polyethylene, polyimide; the granularity range of the binder is less than or equal to 38 mu m.

6. The method according to any one of claims 1 to 5, wherein in the step of preparing the first mixture, the halide solid electrolyte powder, a binder, and a lubricant are mixed by ball milling, air flow mixing, or a pulverizer.

7. The method for producing a solid electrolyte membrane according to any one of claims 1 to 5, wherein in the step of producing the solid electrolyte membrane, the second mixture is subjected to rolling treatment by means of rolling and/or flat plate extrusion.

8. The method for producing a solid electrolyte membrane according to any one of claims 1 to 5, wherein the thickness of the solid electrolyte membrane is 5 μm to 200 μm.

9. A solid electrolyte membrane, characterized in that it is prepared according to the preparation method of any one of claims 1 to 8.

10. A lithium ion battery comprising the solid electrolyte membrane of claim 9.