A moisture-resistant sulfide nanomaterial, a preparation method and application thereof

Abstract

The application discloses a kind of moisture-resistant sulfide nanomaterials and preparation method, application thereof, belong to all-solid battery technical field.Its preparation method includes: sulfide electrolyte material and functionalized additive are mixed with low polarity solvent, sand grinding is refined, and slurry is obtained;The functionalized additive is hydrophobic silicon dioxide nano powder, and the mass ratio of the functionalized additive to sulfide electrolyte material is less than 5%;The slurry is sequentially subjected to solid-liquid separation and drying, and the moisture-resistant sulfide nanomaterial is obtained.The application obtains nanoscale particle size sulfide sample while taking into account the moisture resistance and easy dispersion characteristics of the sample;This way makes up for the neglect of air stability and processing performance of the sample during sulfide electrolyte refinement, which is beneficial to the application in battery preparation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of all-solid-state batteries, and particularly relates to a moisture-resistant sulfide nanomaterial and a preparation method and application thereof, which can be used for preparing batteries such as sulfide electrolytes. BACKGROUND

[0002] With the vigorous development of new energy (electric) vehicles, portable electronic devices and high-capacity energy storage systems, strict requirements are put forward for the safety performance, energy density and working temperature range of lithium ion batteries. Although commercial lithium ion batteries are widely welcomed due to their long cycle life, low self-discharge rate and high discharge capacity, etc., but the organic liquid electrolyte is usually used in them, and the problems of its own limited thermal stability and electrochemical stability cause people's concern and worry about the safety and durability of traditional liquid lithium ion batteries. Under this background, solid-state electrolytes are widely concerned due to their excellent thermal stability and solid-state characteristics. Among them, sulfide electrolytes have excellent ionic conductivity (>10 -2 mS / cm) and good mechanical properties, and are considered to be one of the most promising next-generation solid-state electrolytes.

[0003] For solid-state electrolyte batteries, the solid-solid contact between the electrode and the electrolyte has a smaller interface contact area and a larger interface resistance compared with the full immersion of the electrolyte on the surface of the electrode, which is not conducive to the Li + transport between particles, which has a negative impact on the capacity and rate performance of the battery. In order to increase the solid-solid contact area and expand the Li + transport path, the particle size of the sulfide electrolyte needs to be reduced, and the best particle size distribution is in the nanometer range. In addition, the sulfide electrolyte has poor resistance to moisture in the air, and will undergo a hydrolysis reaction after being exposed to the air, which will cause the destruction of the crystal lattice structure and the sharp drop of the ionic conductivity; and the smaller the particle size of the sulfide electrolyte, the more severe the hydrolysis reaction. At the same time, the reduction of the particle size of the sulfide electrolyte is accompanied by an increase in the surface energy, which leads to the difficulty in dispersing the particle agglomeration and affects the processing performance of the electrolyte. Therefore, the development of a preparation technology for a moisture-resistant and non-agglomerated nanoscale sulfide electrolyte powder material will expand the application scenarios and application environments of the sulfide electrolyte, and accelerate the commercialization process of the sulfide electrolyte and the corresponding solid-state battery.

[0004] The existing preparation technology of sulfide electrolyte can be divided into: using non-polar solvent or polar-non-polar mixed solvent as liquid medium, and realizing the preparation of nanoscale sulfide electrolyte or functionalized nanoscale sulfide electrolyte powder through high-energy ball milling. However, with the reduction of the particle size of the existing sulfide electrolyte, the problems of the increase of the surface energy, the easy agglomeration and the increase of the sensitivity to moisture still exist, which limits the application of the sulfide electrolyte to special environmental requirements, etc., and is not conducive to the cost reduction and commercialization process of the sulfide electrolyte. SUMMARY

[0005] Therefore, the present application aims to provide a sulfide nanomaterial with high moisture resistance, a preparation method and application thereof.

[0006] The present application provides a preparation method of a sulfide nanomaterial with moisture resistance, comprising the following steps:

[0007] The sulfide electrolyte material and the functionalized additive are mixed with a low-polarity solvent, and sand milling is performed to obtain a slurry; the functionalized additive is hydrophobic silica nanopowder, and the mass ratio of the functionalized additive to the sulfide electrolyte material is less than 5%; the low-polarity solvent has nucleophilic sites, and the room temperature viscosity of the low-polarity solvent is greater than 0.7 mPa·s;

[0008] The slurry is sequentially subjected to solid-liquid separation and drying to obtain a sulfide nanomaterial with moisture resistance.

[0009] In specific embodiments of the present application, the sulfide electrolyte material includes Argyrodite-type, Thio-LISICON-type or LGPS-type sulfide electrolyte, preferably Argyrodite-type sulfide electrolyte, including Li 6-a PS 5-a X 1+a at least one of Cl, Br and I.

[0010] In specific embodiments of the present application, the functionalized additive is obtained by hydrophobic modification of the surface of silica (SiO2) with polydimethylsiloxane or trimethylfluorosilane; the particle size of the functionalized additive is 7-100 nm, preferably 7-50 nm, and further 7-40 nm.

[0011] In specific embodiments of the present application, the mass ratio of the functionalized additive to the sulfide electrolyte material is 0.5-3%.

[0012] In specific embodiments of the present application, the low-polarity solvent is at least one of butyl acetate, isobutyl isobutyrate, butyl hexanoate, dibutyl ether, anisole and 3-heptanone.

[0013] In specific embodiments of the present application, the sand milling is performed in a grinding medium using a sand milling device; the sand milling device is a vertical sand mill, a horizontal sand mill or a basket sand mill, preferably a vertical sand mill; the linear speed of the sand milling is 5-15 m / s, preferably 6-10 m / s.

[0014] In a specific embodiment of the present application, the grinding medium is a zirconium oxide ball (ZrO2 ball) with a particle size of 0.6-1 mm; the ball-to-fine mass ratio in the sand milling is 1:8-20, preferably 1:10-20, and the sand milling time is 0.5-5 h, preferably 0.5-2 h.

[0015] In a specific embodiment of the present application, the solid content of the slurry is 20-45%, preferably 20-35%; the solid-liquid separation is by filter screen filtration; and the drying is by vacuum drying, freeze drying or argon-vacuum drying.

[0016] The present application provides a moisture-resistant sulfide nanomaterial obtained by the preparation method as described above, wherein the D50 of the moisture-resistant sulfide nanomaterial is less than 500 nm.

[0017] In addition, the present application provides the use of the sulfide nanomaterial as described above as an electrolyte in a battery.

[0018] Compared with the prior art, the present application refines and surface-modifies the sulfide electrolyte material in a medium composed of a specific low-polarity solvent and a functionalized additive (hydrophobic nanosilica), so as to form a moisture-resistant nanoscale powder material. In the present application, the dispersibility of the low-polarity solvent and the coordination between the hydrophobic functionalized additive are utilized to reduce the nucleophilic attack ability of the solvent on the sulfide electrolyte, which is conducive to improving the ionic conductivity of the electrolyte. Meanwhile, the functionalized additive is coated on the surface of the sulfide particles, and the hydrophobicity and low surface energy of the functionalized additive not only improve the air stability of the sulfide electrolyte, but also reduce the van der Waals force between the particles, so as to obtain a nanoscale (D50<500 nm) sulfide electrolyte powder with high moisture resistance and low agglomeration. The present application not only obtains a nanoscale sulfide sample, but also takes into account the moisture resistance and easy dispersion of the sample; this method makes up for the neglect of the air stability and processability of the sample during the refinement of the sulfide electrolyte, which is conducive to the application in the preparation of batteries. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the X-ray diffraction pattern of the electrolyte nanometer powder of Example 1 of the present application;

[0020] Figure 2 is the particle size distribution graph of the electrolyte nanometer powder of Example 1 of the present application;

[0021] Figure 3 is the scanning electron microscope graph of the electrolyte nanometer powder of Example 1 of the present application;

[0022] Figure 4 is the X-ray diffraction pattern of the electrolyte powder of Comparative Example 1 of the present application;

[0023] Figure 5 is a particle size distribution diagram of the electrolyte powder of the present application comparative example 1;

[0024] Figure 6 is a scanning electron microscope diagram of the electrolyte powder of the present application comparative example 1. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with examples. Unless otherwise defined, all professional terms used below have the same meaning as generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific examples and are not intended to limit the protection scope of the present application.

[0026] The present application provides a preparation method of a moisture-resistant sulfide nanomaterial, comprising the following steps:

[0027] Mixing the sulfide electrolyte material and the functionalized additive with a low-polarity solvent, performing sand grinding and refining to obtain a slurry; the functionalized additive is hydrophobic silicon dioxide nanopowder, and the mass ratio of the functionalized additive to the sulfide electrolyte material is less than 5%; the low-polarity solvent has nucleophilic sites, and the room temperature viscosity of the low-polarity solvent is greater than 0.7 mPa·s;

[0028] The slurry is sequentially subjected to solid-liquid separation and drying to obtain a moisture-resistant sulfide nanomaterial.

[0029] The sulfide nanomaterial prepared by the present application has high air stability, high moisture resistance, easy dispersion and the like, which is beneficial to its application in solid-state batteries.

[0030] The sulfide nanomaterial described in the embodiments of the present application is a nanoscale sulfide electrolyte powder, and the preparation process is completed in a dry room with a dew point of <-50 DEG C and a temperature of <25 DEG C.

[0031] The embodiments of the present application first weigh the conventional sulfide electrolyte material, as well as a certain proportion of functionalized additives and grinding media in a glove box, and then transfer them all to a grinding device, and then add a low-polarity solvent.

[0032] The sulfide electrolyte material generally has high ionic conductivity, including Argyrodite-type sulfide electrolyte, Thio-LISICON-type sulfide electrolyte and LGPS-type sulfide electrolyte. The Argyrodite-type sulfide electrolyte belongs to cubic crystal system, and the general formula is Li 7-x PS 6-x M x(0 ≤ x ≤ 2, M = Cl, Br, I), which has low production cost and high ionic conductivity, up to 10 -2 mS / cm. Thio-LISICON (or thio-LISICON) belongs to the orthorhombic crystal system, and its general chemical composition formula is Li 4-x Ge 1-x P x S4 (0 ≤ x ≤ 1). Due to the differences in the composition structure, three phase structures appear, namely orthorhombic thio-LISICON (0 < x ≤ 0.6), monoclinic thio-LISICON II (0.6 < x < 0.8) and monoclinic thio-LISICON III (0.8 ≤ x < 1). The LGPS-type sulfide electrolyte, i.e., Li 10 GeP2S 12 , belongs to the tetragonal crystal system, has three-dimensional ion transport channels, and the highest ionic conductivity (> 10 -2 mS / cm). Preferably, the sulfide electrolyte material is an Argyrodite-type sulfide electrolyte. More preferably, the Argyrodite-type sulfide electrolyte is Li 6-a PS 5-a M 1+a at least one of them; where 0 ≤ a ≤ 1, and M is a halogen element, which can be at least one of Cl, Br, and I.

[0033] The functionalized additive is hydrophobic SiO2 nano powder, preferably with a particle size of 7 - 100 nm, more preferably 7 - 40 nm. Specifically, the surface of SiO2 is hydrophobically modified by polydimethylsiloxane or trimethylfluorosilane, and the original silanol groups are replaced by silyl groups to obtain functionalized SiO2 nano powder. The water contact angle of the modified SiO2 nano powder ≥ 120°, and the specific surface area ≤ 120 m 2 / g, which can achieve superhydrophobicity and low surface energy.

[0034] The mass ratio of the functionalized additive to the sulfide electrolyte material is less than 5%, and can be 0.2 - 4.9%; further, the mass ratio of the functionalized additive to the sulfide electrolyte material is 0.5 - 3%, such as 0.5%, 1%, 2.5%, 3%, etc.

[0035] Polarity generally refers to the unevenness of charge distribution in a covalent molecule, and if the distribution is uniform, it is non-polar. The low-polarity solvent described in the embodiments of the present application can be referred to as a dispersible solvent, which has nucleophilic sites and certain viscosity (>0.7 mPa·s, 15-25℃), and can be esters, ethers, etc., specifically at least one of butyl acetate, isobutyl isobutyrate, butyl hexanoate, dibutyl ether, anisole, and 3-heptanone. In some embodiments, the room temperature viscosity of the low-polarity solvent is 0.72 mPa·s (20℃).

[0036] The sand milling refinement in the embodiments of the present application uses a sand milling device to refine the sulfide electrolyte material in a certain amount of grinding medium. Specifically, the sand milling device is a vertical sand mill, a horizontal sand mill or a basket sand mill commonly used in the art, and is preferably a vertical sand mill. The preferred embodiments of the present application can assemble a sand milling tank to the vertical sand mill, and perform the refinement work after three times of argon replacement.

[0037] The dispersible solvent in the embodiments of the present application can uniformly disperse the electrolyte particles in the low-polarity solvent without sedimentation when used for wet refinement of the sulfide electrolyte material, and has good sand milling effect, thereby obtaining a lower particle size and a narrower particle size distribution. The reason mainly lies in that the dispersible solvent in the present application has a higher viscosity (>0.7 mPa·s) compared with non-polar solvents or other polar solvents. When the particles in the solvent sediment due to gravity, they will be subjected to a viscous force opposite to the gravity force. The solvent with a higher viscosity has a greater viscous force, which not only hinders the sedimentation of the particles, but also plays a role in dispersing the powder in the solvent.

[0038] The dispersible solvent in the embodiments of the present application is the low-polarity solvent described above. The nucleophilic sites (such as O and N atoms with lone pair electrons) in the low-polarity solvent can interact with electrophilic atoms or groups. Therefore, the polar solvent can attack the electrophilic sites such as P atoms in the sulfide electrolyte, destroy the internal crystal structure, and reduce the crystallinity and ionic conductivity of the electrolyte. The electrophilic sites Si in the SiO2 functional additive have empty orbitals, which can coordinate with the polar solvent with electron-donating properties, reduce the degree of nucleophilic attack of the polar solvent on the sulfide electrolyte, and help to improve the ionic conductivity retention rate of the sulfide electrolyte. At the same time, the electronegativity of O in SiO2 is large, and the electron cloud around the Si-O bond is biased towards the O atom, making the O atom negatively charged. The mutual attraction between the O atom and the cations in the sulfide electrolyte makes the SiO2 nanoparticles tightly adsorbed on the surface of the sulfide electrolyte to form a coating layer.

[0039] In addition, the decrease of the particle size of the sulfide electrolyte is accompanied by the increase of the specific surface area and the surface energy, which is in an unstable state in energy. At this time, the electrolyte particles will spontaneously adsorb SiO2 nanoparticles to coat the surface to reduce the surface energy of the electrolyte particles, so as to achieve a stable state. After the surface of SiO2 is treated with silane, the hydrophilic silanol groups (-Si-OH) on the surface are replaced by hydrophobic silane groups, which exhibit superhydrophobicity. Moreover, the silane groups have low surface energy, and after being introduced into the surface of SiO2, the surface energy of SiO2 can be significantly reduced, realizing the low surface energy characteristics of SiO2.

[0040] Based on this, when SiO2 is coated on the surface of the sulfide electrolyte particles, on the one hand, the hydrophobic property of SiO2 can prevent water from contacting the electrolyte, thereby improving the moisture resistance of the sulfide. On the other hand, SiO2 can effectively reduce the surface energy of the electrolyte, weaken the van der Waals attraction between the electrolyte particles, so that the electrolyte particles are not easy to agglomerate after being refined and dried, and have good processing performance.

[0041] In the embodiment of the present application, a functional additive with electrophilic property is selected through mechanism analysis, which can coordinate with the nucleophilic site in the low-polarity solvent, thereby reducing the nucleophilic attack ability of the polar solvent on the sulfide electrolyte. The silane groups on the surface of the additive have large steric hindrance, which also weakens the attack degree of the polar solvent on the electrolyte, and is beneficial to improving the ionic conductivity of the electrolyte.

[0042] Specifically, the linear speed of the sand milling refinement can be set to 5-15 m / s, preferably 6-10 m / s; the sand milling time can be 0.5-5 h, preferably 0.5-2 h, further 0.5-1.5 h, and the sand milling process is preferably completed in an argon atmosphere.

[0043] Specifically, the grinding medium is ZrO2 ball, and the particle size is preferably 0.6-1 mm, which is beneficial to the refinement to form nanoscale size. Specifically, the ball-to-material mass ratio of the sand milling refinement is 1:8-20, preferably 1:10-20.

[0044] After the sand milling refinement is completed, the collected slurry is sequentially filtered and dried; and the nanoscale sulfide electrolyte powder material product can be obtained by crushing the dried nanomaterial sample with a powder crusher.

[0045] Specifically, the solid content of the slurry is 20-45%, preferably 20-35%. The filtration of the slurry refers to the filtration of the slurry with the milling balls after sand milling to realize the separation of the balls and the material.

[0046] The drying method includes vacuum drying, freeze drying, argon-vacuum drying, etc., and preferably argon-vacuum drying. Specifically, the argon-vacuum drying refers to that during the drying process, the drying equipment is continuously supplied with argon and continuously vacuumized, and the vacuum degree is maintained at -0.7-0.9 MPa; maintaining a certain vacuum degree can reduce the boiling point of the solvent, which is beneficial to the evaporation of the solvent, and the continuous supply of argon can timely carry away the evaporated organic solvent, preventing the solvent from being re-adsorbed on the sample surface. Preferably, the drying temperature is 160-170℃, and the drying time is 1.5-2h.

[0047] The sulfide nanomaterial prepared by the preparation method has high moisture resistance, high ionic conductivity, and is not easy to agglomerate, and is a nanoscale sulfide electrolyte powder. The D50 of the sulfide nanomaterial is less than 500nm, for example, between 400-499nm. D represents the diameter of the powder particles, and D50 represents the diameter of the cumulative 50% point (or 50% passing particle size). The median particle size, also known as D50, refers to the characteristic particle size corresponding to the cumulative distribution percentage of 50% in the particle group, and its physical meaning is that the volume (number) of particles greater than or less than the diameter accounts for 50% of the total volume (total number).

[0048] In addition, the application also provides the application of the sulfide nanomaterial as an electrolyte in a battery. In some embodiments, the sulfide nanomaterial is a modified sulfide electrolyte, and the ionic conductivity is greater than 1.9mS / cm; the ionic conductivity retention rate in the air is good, which is beneficial to the preparation of solid-state batteries.

[0049] In order to better understand the technical content of the present application, the following specific embodiments are provided to further illustrate the present application. The raw materials involved can be conventional commercial products; wherein the initial particle size of the sulfide electrolyte is D50=15-20μm; the hydrophobic SiO2nanopowder parameters are: particle size 7-40nm, specific surface area ≤120m 2 / g, purity >99.8%, contact angle ≥120°.

[0050] Example 1:

[0051] In a glove box, 100g of Li 5.5 PS 4.5 Cl 1.5Sulfide electrolyte material, 1 g hydrophobic SiO2nanopowder, 1 kg ZrO2spheres with a diameter of 0.6 mm, and all were transferred into a sand mill tank; after adding 300 g isobutyl isobutyrate solvent, the sand mill tank was assembled onto a vertical sand mill, and after three times of argon replacement, the refinement work was carried out. The sand mill line speed was set to 8 m / s, the sand mill time was 1 h, and the sand mill process was completed in an argon atmosphere. After the sand mill was completed, the grinding balls were separated out by a vacuum filter, and the collected slurry (solid content of 25%) was placed in a vacuum explosion-proof drying box for argon-vacuum drying, with a drying temperature of 170°C and a drying time of 2 h. After drying, the sample was crushed by a powdering machine to obtain a nanoscale sulfide electrolyte powder.

[0052] As Figure 1 , Figure 2 , Figure 3 , respectively, are the X-ray diffraction (XRD) diagram, the particle size distribution diagram, and the scanning electron microscope (SEM) diagram of the electrolyte nanopowder. After adding the functionalized additive, the diffraction peaks in the XRD diagram of the refined electrolyte are Li 5.5 PS 4.5 Cl 1.5 characteristic peaks, and no other impurity phase peaks appear, and a pure phase electrolyte nanopowder is obtained after refinement. In the SEM diagram, the electrolyte particles are uniform in size and uniformly dispersed, with a uniform SiO2nanopowder coating on the surface, and the particle size is less than 1 μm. The particle size distribution curve shows a normal distribution shape, with a narrow particle size distribution and Dmax<1 μm, corresponding to the SEM test results.

[0053] Example 2:

[0054] In a glove box, 100 g Li6PS5Cl sulfide electrolyte, 1 g hydrophobic SiO2nanopowder, and 1 kg ZrO2spheres with a diameter of 0.6 mm were weighed and transferred into a sand mill tank; after adding 300 g isobutyl isobutyrate solvent, the sand mill tank was assembled onto a vertical sand mill, and after three times of argon replacement, the refinement work was carried out. The sand mill line speed was set to 8 m / s, the sand mill time was 1 h, and the sand mill process was completed in an argon atmosphere. After the sand mill was completed, the grinding balls were separated out by a vacuum filter, and the collected slurry was placed in a vacuum explosion-proof drying box for argon-vacuum drying, with a drying temperature of 170°C and a drying time of 2 h. After drying, the sample was crushed by a powdering machine to obtain a nanoscale sulfide electrolyte powder.

[0055] Example 3:

[0056] In a glove box, 100 g Li 5.5 PS 4.5 Cl 1.5Sulfide electrolyte, 1 g hydrophobic Si02nanopowder, 1 kg 0.6 mm diameter Zr02spheres, and all were transferred into the sand mill pot; after adding 300 g of butyl acetate solvent, the sand mill pot was assembled onto the vertical sand mill, and after three times of argon replacement, the refinement work was carried out. The sand mill line speed was set to 8 m / s, the sand mill time was 1 h, and the sand mill process was completed under argon atmosphere. After the sand mill was completed, the grinding balls were separated out using a vacuum filter, and the collected slurry was placed in a vacuum explosion-proof drying box for argon-vacuum drying, with a drying temperature of 170 °C and a drying time of 2 h. The dried sample was crushed by a powdering machine to obtain nanoscale sulfide electrolyte powder.

[0057] Example 4:

[0058] In a glove box, 100 g of Li 5.5 PS 4.5 Cl 1.5 Sulfide electrolyte, 1 g hydrophobic Si02nanopowder, 1 kg 0.6 mm diameter Zr02spheres, and all were transferred into the sand mill pot; after adding 300 g of butyl acetate solvent, the sand mill pot was assembled onto the vertical sand mill, and after three times of argon replacement, the refinement work was carried out. The sand mill line speed was set to 8 m / s, the sand mill time was 1 h, and the sand mill process was completed under argon atmosphere. After the sand mill was completed, the grinding balls were separated out using a vacuum filter, and the collected slurry was placed in a vacuum explosion-proof drying box for argon-vacuum drying, with a drying temperature of 170 °C and a drying time of 2 h. The dried sample was crushed by a powdering machine to obtain nanoscale sulfide electrolyte powder.

[0059] Example 5:

[0060] In a glove box, 100 g of Li 5.5 PS 4.5 Cl 1.5 Sulfide electrolyte, 1 g hydrophobic Si02nanopowder, 1 kg 0.6 mm diameter Zr02spheres, and all were transferred into the sand mill pot; after adding 300 g of butyl acetate solvent, the sand mill pot was assembled onto the vertical sand mill, and after three times of argon replacement, the refinement work was carried out. The sand mill line speed was set to 8 m / s, the sand mill time was 1 h, and the sand mill process was completed under argon atmosphere. After the sand mill was completed, the grinding balls were separated out using a vacuum filter, and the collected slurry was placed in a vacuum explosion-proof drying box for argon-vacuum drying, with a drying temperature of 170 °C and a drying time of 2 h. The dried sample was crushed by a powdering machine to obtain nanoscale sulfide electrolyte powder.

[0061] Example 6:

[0062] In a glove box, 100 g of Li 5.5 PS 4.5 Cl 1.5Sulfide electrolyte, 1 g hydrophobic SiO2nanopowder, 1 kg 0.6 mm diameter ZrO2spheres, and all were transferred into the sand mill pot; after adding 300 g anisole solvent, the sand mill pot was assembled to the vertical sand mill, and the refinement work was carried out after three times of argon replacement. The sand mill line speed was set to 10 m / s, the sand mill time was 1 h, and the sand mill process was completed under argon atmosphere. After the sand mill was completed, the grinding balls were separated out by using the vacuum filter, and the collected slurry was placed in the vacuum explosion-proof drying box for argon-vacuum drying, with the drying temperature being 170 °C and the drying time being 2 h. The dried sample was crushed by a powdering machine to obtain nanoscale sulfide electrolyte powder.

[0063] Example 7:

[0064] In a glove box, 100 g Li 5.5 PS 4.5 Cl 1.5 Sulfide electrolyte, 0.5 g hydrophobic SiO2nanopowder, 1 kg 0.6 mm diameter ZrO2spheres, and all were transferred into the sand mill pot; after adding 300 g anisole solvent, the sand mill pot was assembled to the vertical sand mill, and the refinement work was carried out after three times of argon replacement. The sand mill line speed was set to 8 m / s, the sand mill time was 1 h, and the sand mill process was completed under argon atmosphere. After the sand mill was completed, the grinding balls were separated out by using the vacuum filter, and the collected slurry was placed in the vacuum explosion-proof drying box for argon-vacuum drying, with the drying temperature being 170 °C and the drying time being 2 h. The dried sample was crushed by a powdering machine to obtain nanoscale sulfide electrolyte powder.

[0065] Example 8:

[0066] In a glove box, 100 g Li 5.5 PS 4.5 Cl 1.5 Sulfide electrolyte, 3 g hydrophobic SiO2nanopowder, 1 kg 0.6 mm diameter ZrO2spheres, and all were transferred into the sand mill pot; after adding 300 g anisole solvent, the sand mill pot was assembled to the vertical sand mill, and the refinement work was carried out after three times of argon replacement. The sand mill line speed was set to 8 m / s, the sand mill time was 1 h, and the sand mill process was completed under argon atmosphere. After the sand mill was completed, the grinding balls were separated out by using the vacuum filter, and the collected slurry was placed in the vacuum explosion-proof drying box for argon-vacuum drying, with the drying temperature being 170 °C and the drying time being 2 h. The dried sample was crushed by a powdering machine to obtain nanoscale sulfide electrolyte powder.

[0067] Comparative Example 1:

[0068] In a glove box, 100 g Li 5.5 PS 4.5 Cl 1.5Sulfide electrolyte, 1 kg 0.6 mm diameter ZrO2 ball beads, and all transferred to the sand mill tank; after adding 300 g of isobutyl isobutyrate solvent, the sand mill tank is assembled to the vertical sand mill, and after three times of argon replacement, the refinement work is carried out. Set the sand mill line speed to 8 m / s, the sand mill time to 1 h, and the sand mill process is completed in an argon atmosphere. After the sand mill is completed, the grinding balls are separated out with a vacuum filter, and the collected slurry is placed in a vacuum explosion-proof drying box for argon-vacuum drying, with a drying temperature of 170°C and a drying time of 2 h. The dried sample is crushed by a powdering machine to obtain a refined sulfide electrolyte powder.

[0069] As Figure 4 , Figure 5 , Figure 6 , respectively, are the XRD pattern, particle size distribution diagram, and SEM diagram of the electrolyte powder. When no functional additive is added, the XRD of the refined sample appears a LiCl decomposition peak near 35°, indicating that a serious side reaction occurs between the low-polarity solvent and the sulfide electrolyte, leading to electrolyte decomposition. Serious agglomeration occurs in the SEM diagram, and primary particles are easily agglomerated into larger secondary spherical particles, leading to a sharp increase in the size of the secondary particles. The particle size distribution diagram shows a serious tailing phenomenon, indicating that the particle size distribution is too wide and the particle size is too large, corresponding to the SEM results.

[0070] Comparative Example 2:

[0071] In a glove box, 100 g of Li 5.5 PS 4.5 Cl 1.5 Sulfide electrolyte, 0.1 g of hydrophobic SiO2 nano-powder, 1 kg of 0.6 mm diameter ZrO2 ball beads, and all transferred to the sand mill tank; after adding 300 g of isobutyl isobutyrate solvent, the sand mill tank is assembled to the vertical sand mill, and after three times of argon replacement, the refinement work is carried out. Set the sand mill line speed to 8 m / s, the sand mill time to 1 h, and the sand mill process is completed in an argon atmosphere. After the sand mill is completed, the grinding balls are separated out with a vacuum filter, and the collected slurry is placed in a vacuum explosion-proof drying box for argon-vacuum drying, with a drying temperature of 170°C and a drying time of 2 h. The dried sample is crushed by a powdering machine to obtain a refined sulfide electrolyte powder.

[0072] Comparative Example 3:

[0073] In a glove box, 100 g of Li 5.5 PS 4.5 Cl 1.5Sulfide electrolyte, 5 g hydrophobic SiO2nanopowder, 1 kg 0.6 mm diameter ZrO2spheres, and all were transferred into the sand mill pot; after adding 300 g isobutyl isobutyrate solvent, the sand mill pot was assembled to the vertical sand mill, and the refinement work was carried out after three times of argon replacement. The sand mill line speed was set to 8 m / s, the sand mill time was 1 h, and the sand mill process was completed under argon atmosphere. After the sand mill was completed, the grinding balls were separated out by using the vacuum filter, and the collected slurry was placed in the vacuum explosion-proof drying box for argon-vacuum drying, with the drying temperature being 170 °C and the drying time being 2 h. The dried sample was crushed by using the powdering machine to obtain the refined sulfide electrolyte powder.

[0074] Comparative Example 4:

[0075] In the glove box, 100 g Li 5.5 PS 4.5 Cl 1.5 Sulfide electrolyte, 1 g hydrophobic SiO2nanopowder, 1 kg 0.6 mm diameter ZrO2spheres, and all were transferred into the sand mill pot; after adding 300 g ethyl acetate solvent, the sand mill pot was assembled to the vertical sand mill, and the refinement work was carried out after three times of argon replacement. The sand mill line speed was set to 8 m / s, the sand mill time was 1 h, and the sand mill process was completed under argon atmosphere. After the sand mill was completed, the grinding balls were separated out by using the vacuum filter, and the collected slurry was placed in the vacuum explosion-proof drying box for argon-vacuum drying, with the drying temperature being 170 °C and the drying time being 2 h. The dried sample was crushed by using the powdering machine to obtain the refined sulfide electrolyte powder.

[0076] Comparative Example 5:

[0077] In the glove box, 100 g Li 5.5 PS 4.5 Cl 1.5 Sulfide electrolyte, 1 g hydrophobic SiO2nanopowder, 1 kg 0.6 mm diameter ZrO2spheres, and all were transferred into the sand mill pot; after adding 300 g ethyl acetate solvent, the sand mill pot was assembled to the vertical sand mill, and the refinement work was carried out after three times of argon replacement. The sand mill line speed was set to 8 m / s, the sand mill time was 1 h, and the sand mill process was completed under argon atmosphere. After the sand mill was completed, the grinding balls were separated out by using the vacuum filter, and the collected slurry was placed in the vacuum explosion-proof drying box for argon-vacuum drying, with the drying temperature being 170 °C and the drying time being 2 h. The dried sample was crushed by using the powdering machine to obtain the refined sulfide electrolyte powder.

[0078] Comparative Example 6:

[0079] In the glove box, 100 g Li 5.5 PS 4.5 Cl 1.5Sulfide electrolyte, 1 g hydrophobic SiO2nanopowder, 1 kg 2 mm diameter ZrO2beads, and all were transferred into a sand mill pot; after adding 300 g anisole solvent, the sand mill pot was assembled on a vertical sand mill, and after three times of argon replacement, the refinement work was carried out. The sand mill line speed was set to 8 m / s, the sand mill time was 1 h, and the sand mill process was completed in an argon atmosphere. After the sand mill was completed, the grinding balls were separated out by a vacuum filter, and the collected slurry was placed in a vacuum explosion-proof drying box for argon-vacuum drying, with a drying temperature of 170°C and a drying time of 2 h. The dried sample was crushed by a powdering machine to obtain a refined sulfide electrolyte powder.

[0080] The samples prepared in the above examples and comparative examples were subjected to performance testing, and the test methods and results are as follows.

[0081] 1. Ion conductivity test: 130 mg of sulfide electrolyte was weighed into a test mold with a diameter of 10 mm, and was pressed into a sheet at 360 MPa, with stainless steel as the blocking electrode, and an electrochemical workstation was used to test the electrochemical impedance of the sulfide electrolyte in the range of 1 MHz-1 Hz.

[0082] 2. Particle size test: A Malvern laser particle size analyzer was used to test the particle size distribution of the sulfide electrolyte powder.

[0083] 3. Air stability test: The sulfide electrolyte sample was exposed to a dry room at <-30°C for 24 h, and its ion conductivity was tested, and the ion conductivity retention rate was calculated.

[0084] Table 1 Test results in the examples of the present application

[0085]

[0086] Comparing the results of Example 1 and Comparative Example 1, it can be seen that the addition of hydrophobic SiO2nanopowder can prevent the sulfide electrolyte fine powder from agglomerating, and the particle size distribution does not have a tailing phenomenon; and, Comparative Example 1 cannot prevent the attack of polar solvents and moisture on the sulfide electrolyte, causing the electrolyte to decompose and the ion conductivity to decrease.

[0087] Comparing the results of Example 1, Example 3, Example 4, and Comparative Example 4, it can be seen that the low viscosity (0.45 mPa·s) ethyl acetate solvent has almost no dispersing effect on the sulfide electrolyte, causing the electrolyte to settle; in the sand mill process, the phenomenon of sticking to the balls, walls, and bottom is easy to occur, resulting in poor sand mill effect, large particle size, and failure to achieve nanoscale size.

[0088] Compared with the results of Example 1, Example 7, Example 8 and Comparative Example 2, Comparative Example 3, when the amount of hydrophobic SiO2 nano powder is too small, the surface of the sulfide electrolyte cannot be completely coated, the electrostatic shielding ability between electrolyte particles is weakened, the ability to inhibit electrolyte hydrolysis and decomposition is reduced, resulting in micro-agglomeration of the refined particles, slight decrease of ion conductivity, and poor air stability. When the amount of hydrophobic SiO2 nano powder is too large, the thickness of the coating layer on the surface of the sulfide electrolyte increases, causing the interfacial resistance to increase, which is not conducive to the transmission of Li + , resulting in a serious decrease in ion conductivity.

[0089] Compared with the results of Example 4, Comparative Example 5 and Comparative Example 6, when the particle size of the grinding ball is too large, the effective grinding times and grinding area are reduced, resulting in insufficient grinding effect, large particle size and wide particle size distribution; when the particle size of the grinding ball is too small, the kinetic energy of the grinding ball is small, and the degree of particle breakage is limited, which can result in low grinding efficiency and the presence of large particles. The sample with large particle size has a higher ion conductivity.

[0090] The reason for the low ion conductivity of the refined product in Example 2 is that the ion conductivity of the initial Li6PS5Cl electrolyte (>4 mS / cm) is lower than that of Li 5.5 PS 4.5 Cl 1.5 (>9 mS / cm).

[0091] From the above examples, it can be seen that in the present application, the sulfide electrolyte material is refined by sand milling in a medium composed of a specific dispersing solvent and a functional additive. The functional additive modifies the surface of the sulfide by using its superhydrophobicity and low surface energy, so that the sulfide has hydrophobicity and is not easy to agglomerate. At the same time, the functional additive interacts with the dispersing solvent, which can weaken the nucleophilic attack ability of the dispersing solvent on the sulfide electrolyte, so as to obtain a nano-sized sulfide electrolyte powder with high moisture resistance, high ion conductivity and not easy to agglomerate, which is beneficial to the application in corresponding solid-state batteries, etc. The preparation method of the present application is simple and easy to operate, and has low cost.

[0092] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement or improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a moisture-resistant sulfide nanomaterial, characterized in that, Includes the following steps: A sulfide electrolyte material and a functionalized additive are mixed with a low-polarity solvent and then finely milled to obtain a slurry. The functionalized additive is a hydrophobic silica nanoparticle, and the functionalized additive accounts for 0.5-3% of the mass of the sulfide electrolyte material. The low-polarity solvent has nucleophilic sites. The slurry was subjected to solid-liquid separation and drying in sequence to obtain moisture-resistant sulfide nanomaterials. The functionalized additive is prepared by hydrophobic modification of the silica surface with polydimethylsiloxane or trimethylfluorosilane; the particle size of the functionalized additive is 7-100 nm; the low polarity solvent is at least one of butyl acetate, isobutyl isobutyrate, butyl hexanoate, dibutyl ether, anisole, and 3-heptanone.

2. The preparation method according to claim 1, characterized in that, The sulfide electrolyte material includes Argyrodite type, Thio-LISICON type or LGPS type sulfide electrolyte.

3. The preparation method according to any one of claims 1-2, characterized in that, The sand milling process is carried out using a sand milling device in the grinding media; the sand milling device is a vertical sand mill, a horizontal sand mill, or a basket sand mill; the linear velocity of the sand milling process is 5-15 m / s.

4. The preparation method according to claim 3, characterized in that, The grinding media is zirconia balls with a particle size of 0.6-1 mm; the mass ratio of the balls to the finely ground material is 1:8-20, and the grinding time is 0.5-5 h.

5. The preparation method according to any one of claims 1-2, characterized in that, The slurry has a solid content of 20-45%; the solid-liquid separation is performed by filter screen filtration; and the drying is performed by vacuum drying, freeze drying, or argon-vacuum drying.

6. The moisture-resistant sulfide nanomaterial obtained by the preparation method according to any one of claims 1-5, characterized in that, The D50 of the moisture-resistant sulfide nanomaterial is less than 500 nm.

7. The application of the moisture-resistant sulfide nanomaterial as described in claim 6 as an electrolyte in a battery.

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