Dispersion, method of making and use thereof, battery electrode, battery separator, and lithium ion battery

Abstract

This invention relates to the field of lithium-ion battery technology, and discloses a dispersion, its preparation method and application, battery electrodes, battery separators, and lithium-ion batteries. By introducing nano-silicon into the feed components of the dispersion, the water content in the dispersion is reduced to no more than 800 ppm. This dispersion, as an oxide solid electrolyte slurry, can significantly reduce the water content of the prepared battery electrodes or battery separators, thereby improving the battery's electrical performance and lifespan.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a dispersion and its preparation method and application, battery electrodes, battery separators, and lithium-ion batteries. Background Technology

[0002] Controlling moisture in batteries is a key technical challenge. The main hazards of moisture in batteries include: moisture can cause electrolyte deterioration, the generated gas can increase the internal pressure and thickness of the battery, and the hydrofluoric acid produced can damage the positive and negative electrode materials; moisture can affect the formation of the SEI film and increase the internal resistance of the battery; moisture can react with free lithium ions, resulting in reduced capacity, damage to the SEI film, further reduction in battery capacity, reduced cycle life, and even battery failure.

[0003] Traditional methods of water control involve controlling the dew point in the battery manufacturing environment to minimize the introduction of moisture. This requires a lot of human and financial resources and cannot guarantee absolute control over moisture.

[0004] Adding solid electrolytes to the electrodes is a common method to improve battery safety. Solid electrolytes are generally ceramic blocks or large particles synthesized by solid-state methods. They need to go through steps such as dry crushing, wet crushing, and air jet milling to obtain nano-sized particles before they can be introduced into the battery to play a role. During the crushing process, moisture in the environment will gradually be adsorbed on the newly exposed surface of the solid electrolyte. If it cannot be effectively removed, it will lead to battery failure. This moisture gradually turns into crystal water, which requires high temperature and long time baking to remove. However, high temperature baking will cause the nanoparticles to re-aggregate and even cause the solid electrolyte to undergo a phase change. Therefore, the water removal operation is very difficult.

[0005] CN115117436A discloses a method for reducing the moisture content of a nano-ionic conductor solid electrolyte. This method uses a fluorinated silane coupling agent to modify the surface of the solid electrolyte, resulting in a hydrophobically modified nano-ionic conductor solid electrolyte. The moisture content is reduced by decreasing the water absorption of the nano-ionic conductor solid electrolyte. However, this surface modification method is costly and complex. In practice, it can only control the moisture content to around 2000 ppm, not below 1000 ppm. Furthermore, it only prevents the solid electrolyte from absorbing water; it does not solve the problem of high moisture content in the slurry after mixing. Ultimately, the powder in the electrolyte slurry still has a high moisture content, resulting in high moisture content in the processed battery electrodes and increased electrode surface resistance. In addition, surface modification can also affect the surface properties of the electrolyte, such as lithium-ion transport performance, thus affecting battery performance.

[0006] Therefore, it is urgent to solve the problems of high water content in electrolyte slurry and difficulty in reducing water content in batteries. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a dispersion, its preparation method and application, battery electrodes, battery separators, and lithium-ion batteries.

[0008] To achieve the above objectives, a first aspect of the present invention provides a dispersion comprising: oxide particles, silicon-based particles, and an organic solvent;

[0009] The silicon-based particle has a core and a shell covering the core; wherein the core is elemental silicon and the shell is SiOx; wherein 0 < x ≤ 2.

[0010] A second aspect of the present invention provides a method for preparing a dispersion, comprising: mixing oxide particles, nano-silicon particles and an organic solvent to obtain a dispersion.

[0011] The third aspect of the present invention provides a dispersion prepared by the preparation method described in the second aspect above.

[0012] The fourth aspect of this invention provides the application of the method for preparing the dispersion described in the second aspect above in battery manufacturing.

[0013] The fifth aspect of the present invention provides a battery electrode sheet, which is prepared from raw materials including the dispersion, electrode active material and current collector described in the first or third aspect above.

[0014] The sixth aspect of the present invention provides a battery separator, which is prepared from raw materials including the dispersion and base film described in the first or third aspect above.

[0015] The seventh aspect of the present invention provides a lithium-ion battery comprising the battery electrode sheet described in the fifth aspect and / or the battery separator described in the sixth aspect.

[0016] This invention introduces nano-silicon into the feed components of a dispersion (e.g., a solid electrolyte slurry), reducing the water content in the dispersion to no more than 800 ppm and solving the problem of the dispersion continuing to adsorb trace amounts of water from the electrode slurry after being introduced. The dispersion obtained by this invention can be used as an electrolyte slurry for batteries, with the primary advantage of low water content. The water content of battery electrodes or separators prepared with it is significantly reduced, which can significantly improve the electrical performance and lifespan of the battery. In addition, the silicon-based particles in the dispersion have a silicon oxide shell, which is more conducive to ion conduction. Therefore, using the dispersion provided by this invention is beneficial to improving the cycle performance of lithium-ion batteries, reducing battery internal resistance, and increasing battery rate performance. Attached Figure Description

[0017] Figure 1XPS image of the solid obtained after drying the dispersion P1 prepared in Example 1. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] The first aspect of the present invention provides a dispersion comprising: oxide particles, silicon-based particles, and an organic solvent;

[0020] The silicon-based particle has a core and a shell covering the core; wherein the core is elemental silicon and the shell is silicon oxide SiOx; wherein 0 < x ≤ 2.

[0021] According to the present invention, the dispersion can be used as an oxide solid electrolyte slurry or an oxide ceramic slurry.

[0022] According to the present invention, the water content of the dispersion is ≤800ppm. As an oxide solid electrolyte slurry, it can reduce the water content in the prepared positive electrode sheet, which is beneficial to reducing the sheet resistance and internal resistance of the positive electrode sheet, thereby reducing the temperature rise during battery operation and improving the cycle performance, rate performance and safety performance of the battery. For example, the water content of the dispersion can be 5ppm, 10ppm, 50ppm, 80ppm, 100ppm, 120ppm, 150ppn, 180ppm, 200ppm, 220ppm, 250ppm, 270ppn, 300ppm, 350ppm, 400ppm, 450ppm, 500ppm, 550ppm, 600ppn, 650ppm, 700ppm, 750ppm, or 800ppm.

[0023] According to the present invention, in a preferred embodiment, the water content of the dispersion is ≤500ppm.

[0024] According to the present invention, in a more preferred embodiment, the water content of the dispersion is ≤300ppm.

[0025] According to the present invention, the D50 of the solid phase in the dispersion is 100-5000 nm. In the present invention, the solid phase in the dispersion includes all solid substances in the dispersion that are insoluble in the organic solvent (e.g., the oxide particles and the silicon-based particles). By controlling the D50 of the solid phase in the dispersion to be within the above range, it is more beneficial to maintain the stability of the slurry.

[0026] In this invention, the D50 of the solid phase in the dispersion is determined by a laser particle size analyzer.

[0027] According to the present invention, in the dispersion, the silicon-based particles are obtained by reacting raw material elemental nano-silicon with water contained in other raw materials of the dispersion (e.g., oxide particles, organic solvents). The silicon-based particles exhibit a core-shell structure, having an elemental silicon core and a silicon oxide shell, wherein the silicon oxide material of the shell has good electrolyte compatibility and can enhance the interfacial stability of the cathode material, which is beneficial to improving the rate performance of the battery.

[0028] According to the present invention, in the dispersion, the D50 of the silicon-based particles is 1-500 nm, for example, it can be 1 nm, 2 nm, 5 nm, 10 nm, 20 nm, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, 230 nm, 260 nm, 290 nm, 300 nm, 310 nm, 330 nm, 350 nm, 380 nm, 400 nm, 430 nm, 450 nm, 480 nm, or 500 nm. Preferably, the D50 of the silicon-based particles is 10-300 nm.

[0029] In this invention, the D50 of the silicon-based particles in the dispersion is determined by SEM mapping.

[0030] According to the present invention, the shell thickness of the silicon-based particles in the dispersion is 1-100 nm, for example, it can be 1 nm, 2 nm, 5 nm, 8 nm, 10 nm, 15 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 80 nm, or 100 nm. In the present invention, the shell thickness of the silicon-based particles is related to the amount of silicon oxide generated by the reaction of the raw material elemental nano-silicon and water; the thicker the shell, the greater the amount of silicon oxide generated. When the shell thickness of the silicon-based particles in the dispersion is within the above-mentioned range, the dispersion, as an oxide solid electrolyte slurry, can reduce the internal resistance of the resulting battery, thereby improving the battery's cycle performance, coulombic efficiency, and safety.

[0031] In this invention, the shell thickness of the silicon-based particles is measured by X-ray photoelectron spectroscopy (XPS).

[0032] According to the present invention, in the dispersion, the weight ratio of oxide particles:silicon-based particles:organic solvent is 1:(0.05-0.44):(0.17-99), which is beneficial to the full cooperation of the solid components in the dispersion.

[0033] According to the present invention, preferably, in the dispersion, the weight ratio of oxide particles:silicon-based particles:organic solvent is 1:(0.06-0.14):(1-6.7).

[0034] According to the present invention, in the dispersion, the oxide particles may be selected from at least one of alumina, cerium oxide, titanium oxide, and inorganic oxide solid electrolytes. When the oxide particles are inorganic oxide solid electrolytes, the dispersion can be used as an oxide solid electrolyte slurry. When the oxide particles are selected from at least one of alumina, cerium oxide, and titanium oxide, the dispersion can be used as an oxide ceramic slurry.

[0035] According to the present invention, the inorganic oxide solid electrolyte is broadly defined, and any inorganic oxide solid electrolyte in the battery field can be used. Preferably, the inorganic oxide solid electrolyte can be selected from solid electrolytes containing at least one element selected from Li, Na, and K.

[0036] According to the present invention, more preferably, the inorganic oxide solid electrolyte can be selected from perovskite, anti-perovskite, garnet, LISICON type electrolyte, NASICON type electrolyte, Li 1-x1 Ti 1-x1 M1 x1 OPO4, Li 1+x2 H 1-x2 Al(PO4)O 1- y M2 y LiAlPO4F x3 (OH) 1-x3 At least one of Na-β / β″-Al2O3; wherein M1 is selected from at least one of Nb, Ta, and Sb; M2 is selected from at least one of F, Cl, Br, and I; 0≤x1≤0.7, 0≤x2<1, 0≤x3<1, 0 <y<0.1。

[0037] According to the present invention, more preferably, the inorganic oxide solid electrolyte may be selected from at least one of LLZO, LLTO, LLZTO, LATP, NZSP and LAPF.

[0038] According to the present invention, the organic solvent in the dispersion is broadly defined, and any organic solvent that can be used in the battery field to prepare slurries can be used. Preferably, the organic solvent may be selected from at least one of N,N-dimethylformamide, dimethylacetamide, 1,3-dioxolane, dimethyl carbonate, ethanol, and N-methylpyrrolidone.

[0039] According to the present invention, the dispersion may further contain elemental nano-silicon, which facilitates the reaction between the elemental nano-silicon and the water in the electrode slurry after the dispersion is introduced into the electrode slurry to further remove water. Preferably, the D50 of the elemental nano-silicon is 1-500 nm, more preferably 10-300 nm.

[0040] The dispersion provided by this invention can be used as an oxide solid electrolyte slurry or an oxide ceramic slurry, with a water content of ≤800ppm. It has the characteristic of low water content. Compared with conventional dispersions in the prior art, the water content of battery electrodes or battery separators prepared using this dispersion is significantly reduced, thereby reducing the internal resistance of lithium-ion batteries and improving the cycle performance, rate performance and safety performance of lithium-ion batteries.

[0041] In this invention, the water content of the dispersion is determined by the coulometric method known in the art, specifically by a coulometric moisture analyzer.

[0042] A second aspect of the present invention provides a method for preparing a dispersion, comprising: mixing oxide particles, nano-silicon particles and an organic solvent to obtain a dispersion.

[0043] According to the present invention, in the method for preparing the dispersion, the oxide particles may be selected from at least one of alumina, cerium oxide, titanium oxide, and inorganic oxide solid electrolytes.

[0044] According to the present invention, when the oxide particles are inorganic oxide solid electrolytes, the resulting dispersion can be used as an oxide solid electrolyte slurry.

[0045] According to the present invention, when the oxide particles are selected from at least one of alumina, cerium oxide and titanium oxide, the resulting dispersion can be used as an oxide ceramic slurry.

[0046] According to the present invention, in the method for preparing the dispersion, the sum of the water content of the oxide particles, nano-silicon particles, and organic solvent is ≤3700ppm, for example, it can be less than or equal to: 3700ppm, 3500ppm, 3200ppm, 3000ppm, 2800ppm, 2600ppm, 2500ppm, 2400ppm, 2200ppm, 2000ppm, 1800ppm, 1600ppm, 1500ppm, 1200ppm, 1000ppm, and 800ppm. Preferably, the sum of the water content of the oxide particles, nano-silicon particles, and organic solvent is ≤3000ppm, which is beneficial to obtaining a better water removal effect of nano-silicon and can effectively avoid the disadvantages of conventional high-temperature water removal methods, such as the water removal effect being affected by the environment, unsatisfactory water removal effect, and high water removal cost. More preferably, the sum of the water content of the oxide particles, nano-silicon particles, and organic solvent is ≤2000ppm.

[0047] According to the present invention, in the method for preparing the dispersion, in addition to satisfying the above-mentioned raw material water content, preferably, the water content of the oxide particles fed is ≤3000ppm, the water content of the nano-silicon particles fed is ≤300ppm, and the water content of the solvent fed is ≤400ppm.

[0048] In this invention, the moisture content of oxide particles and nano-silicon particles can be determined by the following method: In a dry room with a dew point ≤ -50℃, weigh approximately 0.3g of the sample to be tested and place it in a moisture bottle. Start the test when the drift value is <10ug / min. Set the parameters as follows: temperature 180℃, test time 400s, gas flow rate 50mL / min, and stirring speed 60%. A Karl Fischer moisture analyzer is used as the testing instrument.

[0049] In this invention, the water content of organic solvent and oxide dispersions can be determined by the following method: Take the sample to be tested using a disposable pipette in a dry room with a dew point ≤ -50℃. Weigh 0.2-0.3g of material using the subtraction method. Start the test when the drift value is <10ug / min, and maintain a stirring speed of 60%. A Karl Fischer moisture analyzer is used as the testing instrument.

[0050] According to the present invention, the method for preparing the dispersion allows for a wide range of species limitations for the inorganic oxide solid electrolyte, and any inorganic oxide solid electrolyte in the battery field can be used. Preferably, the inorganic oxide solid electrolyte can be selected from solid electrolytes containing at least one element selected from Li, Na, and K.

[0051] According to the present invention, in the method for preparing the dispersion, more preferably, the inorganic oxide solid electrolyte can be selected from perovskite, anti-perovskite, garnet, LISICON-type electrolyte, NASICON-type electrolyte, Li 1-x1 Ti 1- x1 M1 x1 OPO4, Li 1+x2 H 1-x2 Al(PO4)O 1-y M2 y LiAlPO4F x3 (OH) 1-x3 At least one of Na-β / β″-Al2O3; wherein M1 is selected from at least one of Nb, Ta, and Sb; M2 is selected from at least one of F, Cl, Br, and I; 0≤x1≤0.7, 0≤x2<1, 0≤x3<1, 0 <y<0.1。

[0052] According to the present invention, in the method for preparing the dispersion, more preferably, the inorganic oxide solid electrolyte can be selected from at least one of LLZO, LLTO, LLZTO, LATP, NZSP and LAPF.

[0053] According to the present invention, the method for preparing the dispersion has a broad definition of the organic solvent, and any organic solvent that can be used in the battery field to prepare slurries can be used. Preferably, the organic solvent may be selected from at least one of N,N-dimethylformamide, dimethylacetamide, 1,3-dioxolane, dimethyl carbonate, ethanol, and N-methylpyrrolidone.

[0054] According to the present invention, in the method for preparing the dispersion, the nano-silicon particles are elemental nano-silicon. Preferably, the D50 of the nano-silicon particles is 1-500 nm, more preferably 10-300 nm.

[0055] In this invention, the source of the nano-silicon particles is not particularly limited. They can be obtained by conventional methods or by commercially available products, as long as they meet the above-mentioned particle size requirements.

[0056] According to the present invention, in the method for preparing the dispersion, preferably, the weight ratio of oxide particles: nano-silicon particles: organic solvent is 1:(0.01-0.4):(0.17-99), and more preferably 1:(0.02-0.1):(1-6.7).

[0057] According to the present invention, in the method for preparing the dispersion, preferably, the D50 of the solid phase in the obtained dispersion can be 100-5000 nm by controlling the particle size of the oxide particles and nano-silicon particles. Furthermore, if the particle size of the raw material oxide particles and nano-silicon particles is too large, the resulting mixed slurry can be ground after mixing to reduce the size of the solid phase particles, thereby achieving a D50 of 100-5000 nm for the solid phase in the obtained dispersion.

[0058] According to the present invention, the mixing method for preparing the dispersion is not particularly limited, as long as it can achieve the goal of fully mixing the raw materials to obtain a uniform dispersion (or mixed slurry).

[0059] According to the present invention, the dispersion obtained by the preparation method contains oxide particles, silicon-based particles, and an organic solvent; wherein the silicon-based particles have a core and a shell covering the core, the core being elemental silicon and the shell being silicon oxide (SiO2). xThe dispersion obtained by this method has a water content ≤800ppm; preferably, the D50 of the solid phase in the dispersion is 100-5000nm; preferably, the D50 of the silicon-based particles in the dispersion is 1-500nm, and the shell thickness of the silicon-based particles is 1-100nm; preferably, the weight ratio of oxide particles: silicon-based particles: organic solvent in the dispersion is 1:(0.05-0.44):(0.17-99).

[0060] This invention introduces nano-silicon into the raw material components of a dispersion, utilizing the reaction between nano-silicon and water to reduce the water content of the dispersion, achieving a water content ≤800ppm. This reduces moisture on the surface of oxide particles in the dispersion and prevents the dispersion from adsorbing trace amounts of water from the electrode slurry after introduction. The dispersion prepared by this method can be used for positive and negative electrode blending or separator coating, significantly reducing the water content of the prepared battery electrodes or separators, thereby improving the cycle performance of lithium-ion batteries, reducing internal resistance, and increasing rate performance.

[0061] The third aspect of the present invention provides a dispersion prepared by the preparation method described in the second aspect above.

[0062] According to the present invention, the dispersion prepared by the preparation method described in the second aspect has the same composition and properties as the dispersion described in the first aspect, and will not be repeated here.

[0063] The fourth aspect of this invention provides the application of the method for preparing the dispersion described in the second aspect above in battery manufacturing.

[0064] According to the present invention, the method for preparing the dispersion provided by the present invention can be applied to battery manufacturing, for example, to prepare battery electrodes or battery separators, which can significantly reduce the water content of battery electrodes or battery separators, thereby reducing the water content of the battery and improving the cycle performance and rate performance of the battery.

[0065] The fifth aspect of the present invention provides a battery electrode sheet, which is prepared from raw materials including the dispersion, electrode active material and current collector described in the first or third aspect above.

[0066] According to the present invention, the battery electrode provided by the present invention can be prepared by coating the current collector (positive electrode current collector or negative electrode current collector) onto the surface of the dispersion liquid described in the first or third aspect described above. Because the dispersion liquid used in the preparation process has a low water content and contains silicon-based particles with a specific structure, compared with conventional dispersion liquids using existing technologies, under the same conditions of other raw materials and preparation conditions besides the dispersion liquid, the battery electrode provided by the present invention has a lower water content and a lower sheet resistivity.

[0067] In this invention, the electrode active materials (e.g., positive electrode active materials, negative electrode active materials, etc.), current collectors, and other auxiliary raw materials known in the art (e.g., conductive agents, binders, and solvents, etc.) in the battery electrode sheet are not particularly limited, and conventional choices in the art can be used.

[0068] The sixth aspect of the present invention provides a battery separator, which is prepared from raw materials including the dispersion and base film described in the first or third aspect above.

[0069] According to the present invention, the battery separator provided by the present invention can be prepared by coating the dispersion described in the first or third aspect above onto the surface of a base film and then drying and winding it up. Because the dispersion used in the preparation process has a low water content and contains silicon-based particles with a specific structure, compared with conventional dispersions using existing technologies, under the same conditions of other raw materials and preparation conditions besides the dispersion, the battery separator provided by the present invention has a lower water content and is safer.

[0070] In this invention, the base film used in the battery separator is not particularly limited, and conventional choices in the art can be used. For example, the base film can be selected from at least one of porous PP, PE, and PET.

[0071] The seventh aspect of the present invention provides a lithium-ion battery comprising the battery electrode sheet described in the fifth aspect and / or the battery separator described in the sixth aspect.

[0072] The lithium-ion battery provided by this invention, using the battery electrode and / or battery separator provided by this invention, under the same preparation conditions, has a lower water content than lithium-ion batteries using conventional electrodes or battery separators of the prior art, resulting in lower internal resistance and better cycle performance and rate performance.

[0073] The present invention will be described in detail below through examples. Unless otherwise specified, the following examples and comparative examples are all conventional methods; the reagents and materials mentioned are commercially available unless otherwise specified.

[0074] Example 1

[0075] (1) Inorganic oxide solid electrolyte (LATP, water content less than 3000ppm), nano-silicon particles (D50 of 102nm, water content less than 300ppm) and N-methylpyrrolidone (water content less than 400ppm) are mixed to obtain a mixed slurry; wherein, the sum of the water content of LATP, nano-silicon particles and N-methylpyrrolidone is less than 3700ppm;

[0076] The weight ratio of inorganic oxide solid electrolyte, nano-silicon particles, and N-methylpyrrolidone is 1:0.05:4.

[0077] (2) The above mixed slurry is ground in a sand mill to obtain a dispersion P1.

[0078] In dispersion P1, the weight ratio of LATP:silicone particles:organic solvent was 1:0.054:4. The test results for dispersion P1 are shown in Table 1.

[0079] The dispersion P1 was dried, and the resulting solid was subjected to XPS testing. The results are as follows: Figure 1 As shown, the red (Si 2p 13), green (Si 2p 14), and dark blue (Si 2p 15) curves correspond to the sample surface before etching, after etching for 867 s, and after etching for 1734 s, respectively. Figure 1 The surface of the sample powder showed obvious Si 2p binding peaks. The presence of a binding peak at 99 eV indicates the presence of elemental Si, while the presence of a binding peak at 103 eV indicates the presence of SiO2. With increasing etching depth, the Si-SiO2 binding peaks gradually decreased in size, indicating the presence of SiO2. x (101-103eV).

[0080] Example 2

[0081] (1) Inorganic oxide solid electrolyte (LATP, water content less than 3000ppm), nano-silicon particles (D50 of 344nm, water content less than 300ppm) and N-methylpyrrolidone (water content less than 400ppm) are mixed to obtain a mixed slurry; wherein, the sum of the water content of LATP, nano-silicon particles and N-methylpyrrolidone is less than 3700ppm;

[0082] The weight ratio of inorganic oxide solid electrolyte, nano-silicon particles, and N-methylpyrrolidone is 1:0.05:4.

[0083] (2) The above-mentioned mixed slurry was ground in a sand mill to obtain dispersion P2. In dispersion P2, the weight ratio of LATP:silicone particles:organic solvent was 1:0.054:4. The test results of dispersion P2 are shown in Table 1.

[0084] Example 3

[0085] (1) Inorganic oxide solid electrolyte (LiAlPO4F) 0.1 (OH) 0.9LAPF (with a water content of less than 3000 ppm), nano-silicon particles (D50 of 103 nm, with a water content of less than 300 ppm), and N-methylpyrrolidone (with a water content of less than 400 ppm) are mixed to obtain a mixed slurry; wherein the sum of the water content of LAPF, nano-silicon particles, and N-methylpyrrolidone is less than 3700 ppm.

[0086] The weight ratio of inorganic oxide solid electrolyte, nano-silicon particles, and N-methylpyrrolidone is 1:0.05:0.4.

[0087] (2) The above-mentioned mixed slurry was ground in a sand mill to obtain dispersion P3. In dispersion P3, LiAlPO4F 0.1 (OH) 0.9 The weight ratio of silicon-based particles to organic solvent was 1:0.054:4. The test results of dispersion P3 are shown in Table 1.

[0088] Example 4

[0089] (1) An inorganic oxide solid electrolyte (NZSP, with a water content of less than 3000 ppm), nano-silicon particles (D50 of 97 nm, with a water content of less than 300 ppm) and N-methylpyrrolidone (with a water content of less than 400 ppm) are mixed to obtain a mixed slurry; wherein the sum of the water contents of NZSP, nano-silicon particles and N-methylpyrrolidone is less than 3700 ppm;

[0090] The weight ratio of inorganic oxide solid electrolyte, nano-silicon particles, and N-methylpyrrolidone is 1:0.05:0.4.

[0091] (2) The above-mentioned mixed slurry was ground in a sand mill to obtain dispersion P4. In dispersion P4, the weight ratio of NZSP:silicon-based particles:organic solvent was 1:0.054:4. The test results of dispersion P4 are shown in Table 1.

[0092] Example 5

[0093] (1) Alumina particles (water content less than 3000ppm), nano-silicon particles (D50 of 99nm, water content less than 300ppm) and N-methylpyrrolidone (water content less than 400ppm) are mixed to obtain a mixed slurry; wherein the sum of the water content of alumina particles, nano-silicon particles and N-methylpyrrolidone is less than 3700ppm.

[0094] The weight ratio of alumina particles: nano-silicon particles: N-methylpyrrolidone is 1:0.05:0.4.

[0095] (2) The above-mentioned mixed slurry was ground in a sand mill to obtain dispersion P5. In dispersion P5, the weight ratio of alumina particles:silicon-based particles:organic solvent was 1:0.054:4. The test results of dispersion P5 are shown in Table 1.

[0096] Example 6

[0097] (1) Titanium oxide particles (water content less than 3000 ppm), nano-silicon particles (D50 of 103 nm, water content less than 300 ppm) and N-methylpyrrolidone (water content less than 400 ppm) are mixed to obtain a mixed slurry; wherein the sum of the water content of titanium oxide particles, nano-silicon particles and N-methylpyrrolidone is less than 3700 ppm;

[0098] The weight ratio of titanium dioxide particles, nano-silicon particles, and N-methylpyrrolidone is 1:0.05:0.4.

[0099] (2) The above-mentioned mixed slurry was ground in a sand mill to obtain dispersion P6. In dispersion P6, the weight ratio of titanium oxide particles: silicon-based particles: organic solvent was 1:0.054:4. The test results of dispersion P6 are shown in Table 1.

[0100] Comparative Example 1

[0101] The method of Preparation Example 1 was followed, except that the feed consisted of LATP and N-methylpyrrolidone, the feed did not contain silicon nanoparticles, and the weight ratio of LATP to N-methylpyrrolidone was 1:4.05. All other steps and conditions were the same as in Preparation Example 1, resulting in dispersion DP1. The solid phase D50 of dispersion DP1 was 0.206 μm, and the water content was measured to be 2364 ppm.

[0102] Comparative Example 2

[0103] (1) A mixture of LATP modified with fluorinated silane coupling agent (water content less than 1500 ppm, prepared by heating and stirring after mixing LATP with KH-570 at a weight ratio of 1:1) and N-methylpyrrolidone (water content less than 300 ppm) was obtained to form a mixed slurry.

[0104] The weight ratio of LATP modified with fluorinated silane coupling agent to N-methylpyrrolidone was 1:4.05.

[0105] (2) Following the same procedure as in Preparation Example 1 (2), dispersion DP2 was obtained. In dispersion DP2, the weight ratio of LATP modified with fluorosilane coupling agent to organic solvent was 1:4.05. The D50 of the solid phase in the dispersion was 0.195 μm, and the water content of the dispersion was measured to be 1233 ppm.

[0106] Table 1

[0107]

[0108] As can be seen from the data in Table 1, Examples 1-6 of the present invention, by adding elemental nano-silicon as a raw material during the preparation of the dispersion, can significantly reduce the water content of the dispersion compared to the methods of Comparative Examples 1 and 2, and the water content of the obtained dispersion is not higher than 800 ppm.

[0109] Test case

[0110] The positive electrode sheet was prepared under the same conditions using the dispersions P1 and DP1 obtained in Example 1 and Comparative Example 1, as follows:

[0111] The positive electrode active material NCM, carbon nanotubes (conductive agent), PVDF (binder) and NMP (solvent) are thoroughly mixed to prepare a positive electrode slurry (wherein, the weight ratio of NCM:conductive agent:binder:solvent is 97:1:1:1).

[0112] Under the same conditions and parameters, dispersions P1 and DP1 were homogenized with the above positive electrode slurry, and then coated and dried to obtain positive electrode sheets (denoted as S1 and DS1, respectively). The amount of dispersion added was such that the effective component in the dispersion accounted for 1% of the weight of the positive electrode active material.

[0113] The water content (using a Karl Fischer moisture analyzer) and surface resistivity (using a surface resistivity tester) of the positive electrode plates S1 and DS1 were tested, and the results are shown in Table 2.

[0114] Table 2

[0115] Positive electrode film Moisture content / ppm Surface resistance / Ω S1 106 0.512 DS1 183 2.445

[0116] As shown in Table 2, using the dispersion provided by this invention as an oxide solid electrolyte slurry can significantly reduce the water content of the prepared positive electrode sheet, greatly reduce the surface resistance of the positive electrode sheet, and thus reduce the internal resistance of the lithium-ion battery, which is beneficial to improving the cycle performance, rate performance and safety performance of the lithium-ion battery.

[0117] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A dispersion, characterized in that, The dispersion comprises: oxide particles, silicon-based particles, and an organic solvent; The silicon-based particle has a core and a shell covering the core; wherein the core is elemental silicon, and the shell is SiO x ; wherein 0 < x ≤ 2.

2. The dispersion according to claim 1, wherein, The D50 of the solid phase in the dispersion is 100-5000 nm; And / or, the water content of the dispersion is ≤800ppm, preferably ≤500ppm, more preferably ≤300ppm.

3. The dispersion of claim 1 or 2, wherein, The D50 of the silicon-based particles is 1-500nm, preferably 10-300nm; And / or, in the silicon-based particles, the thickness of the outer shell is 1-100 nm; And / or, in the dispersion, the weight ratio of the oxide particles:silicon-based particles:organic solvent is 1:(0.05-0.44):(0.17-99), preferably 1:(0.06-0.14):(1-6.7).

4. The dispersion of any one of claims 1-3, wherein, The oxide particles are selected from at least one of aluminum oxide, cerium oxide, titanium oxide, and inorganic oxide solid electrolytes; Preferably, the inorganic oxide solid electrolyte is selected from solid electrolytes containing at least one element selected from Li, Na and K; Preferably, the inorganic oxide solid electrolyte is selected from perovskite, anti-perovskite, garnet, LISICON type electrolyte, NASICON type electrolyte, and Li 1-x1 Ti 1-x1 M1 x1 OPO4, Li 1+x2 H 1-x2 Al(PO4)O 1-y M2 y LiAlPO4F x3 (OH) 1-x3 At least one of Na-β / β″-Al2O3; wherein M1 is selected from at least one of Nb, Ta, and Sb; M2 is selected from at least one of F, Cl, Br, and I; 0≤x1≤0.7, 0≤x2<1, 0≤x3<1, 0 <y<0.1; And / or, the organic solvent is selected from at least one of N,N-dimethylformamide, dimethylacetamide, 1,3-dioxolane, dimethyl carbonate, ethanol, and N-methylpyrrolidone.

5. A method for producing a dispersion, characterized by, include: The oxide particles, nano-silicon particles, and organic solvent are mixed to obtain a dispersion.

6. The production method according to claim 5, wherein The sum of the water content of the oxide particles, nano-silicon particles and organic solvent is ≤3700ppm; And / or, the weight ratio of the oxide particles: nano-silicon particles: organic solvent is 1:(0.01-0.4):(0.17-99), preferably 1:(0.02-0.1):(1-6.7); And / or, the oxide particles are selected from at least one of alumina, cerium oxide, titanium oxide, and inorganic oxide solid electrolytes; And / or, the D50 of the nano-silicon particles is 1-500 nm, preferably 10-300 nm; And / or, the organic solvent is selected from at least one of N,N-dimethylformamide, dimethylacetamide, 1,3-dioxolane, dimethyl carbonate, ethanol, and N-methylpyrrolidone.

7. A dispersion prepared by the method of claim 5 or 6.

8. The application of the method for preparing the dispersion according to claim 5 or 6 in battery manufacturing.

9. A battery electrode sheet, characterized by, The battery electrode is prepared from raw materials including the dispersion, electrode active material, and current collector as described in any one of claims 1-4 and 7.

10. A battery separator characterized by, The battery separator is prepared from raw materials comprising the dispersion and base film as described in any one of claims 1-4 and 7.

11. A lithium-ion battery comprising the battery electrode of claim 9 and / or the battery separator of claim 10.

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