Jet mill system with improved crushing efficiency

Abstract

The present invention provides a jet mill system with improved pulverizing efficiency, comprising: a compressor for compressing gas flowing in from the outside; a dehumidifier for removing moisture in the gas compressed by the compressor; a filter for filtering foreign matter in the gas from which the moisture is removed by the dehumidifier; and a cooling machine for cooling the gas filtered by the filter and supplying the cooled gas into a grinding body of the jet mill.

Description

Technical Field

[0001] The present invention relates to a jet mill system with improved pulverizing efficiency, and in particular to a jet mill system which can control the temperature of compressed gas below 10°C when pulverizing sulfide solid electrolytes, making it easy to adjust the particle size and preventing adhesion to the grinding body, thereby improving the pulverizing efficiency. Background Art

[0002] In recent years, secondary batteries have been widely used in electronic devices such as smartphones.

[0003] Secondary batteries use lithium as a positive electrode, and are charged by the movement of lithium ions from the positive electrode to the negative electrode, and are discharged and generate electricity by the movement of lithium ions from the negative electrode to the positive electrode.

[0004] Such lithium secondary batteries have the advantages of high energy density and long life, and therefore are widely used in a variety of electronic devices, and in recent years, the demand has been increasing due to the rapid growth of the electric vehicle market.

[0005] However, such lithium secondary batteries use an organic solvent as an electrolyte for ion transfer, and therefore accidents may occur due to leakage or volatilization of the electrolyte, which poses a problem in terms of safety.

[0006] Solid electrolytes developed in recent years are a technology that uses solid-phase sulfide compounds to replace existing liquid-phase electrolytes. Since only lithium ions move inside the electrolyte, there are no side reactions and it has very excellent safety and durability.

[0007] Among the solid electrolytes used in lithium secondary batteries, the compound represented by Li7-XPS6-xClx has a cubic argyrodite-type crystal structure. Due to its high ionic conductivity and electrochemical stability over a wide temperature range, it has attracted much attention as a mass-produced sulfide solid electrolyte.

[0008] This solid electrolyte is prepared into particles of a certain size through a grinding process after synthesis.

[0009] The existing solid electrolyte grinding process usually uses a ball mill. However, for this ball mill, in order to prepare particles less than 10 μm required in the solid electrolyte particles, not only does it take tens of hours of process time, but there are also problems such as the formation of carbon compounds based on solvent reactions and the resulting decrease in conductivity.

[0010] Therefore, in recent years, in order to adjust the particle size of solid electrolytes, a method of dry-grinding particles using a jet mill has been mainly used.

[0011] The jet mill as described above is a device that uses a nozzle to spray compressed air to cause the pulverized raw materials to collide with each other, and a classifier at the upper end of the chamber where the raw materials collide is used to separate the particles according to their particle size, thereby pulverizing the sulfide solid electrolyte (LPSCl).

[0012] However, in the case of sulfide-based solid electrolytes, due to their ductile properties, it is not easy to adjust the particle size when pulverized at a temperature higher than room temperature, and there is a problem of reducing process efficiency due to adhesion inside the grinding body.

[0013] Meanwhile, when carbonic acid is contained in the compressed air supplied to the jet mill, it acts as an impurity, thereby reducing the purity or generating secondary or tertiary by-products, thereby becoming a factor that hinders the performance of the solid electrolyte. Summary of the invention Technical Problems to be Solved by the Invention

[0014] The present invention is proposed to solve the above-mentioned various existing problems. The purpose of the present invention is to provide a jet mill system that can control the temperature of compressed gas to below 10°C when crushing sulfide solid electrolytes, making it easy to adjust the particle size and prevent adhesion to the grinding body, thereby improving the crushing efficiency. Technical Solution

[0015] In order to achieve the above-mentioned purpose, the present invention provides a jet mill system with improved crushing efficiency, comprising: a compressor for compressing gas flowing in from the outside; a dehumidifier for removing moisture from the gas compressed by the compressor; a filter for filtering foreign matter in the gas from which moisture is removed by the dehumidifier; and a cooler for cooling the gas filtered by the filter and supplying the cooled gas to the grinding body of the jet mill.

[0016] At this time, the gas is preferably any one of pure nitrogen, pure argon and air.

[0017] The dehumidifier can dehumidify to a dew point of -90°C.

[0018] Between the dehumidifier and the cooler, there may be arranged in sequence: a pre-treatment filter for filtering foreign matter in the compressed and dehumidified gas; a carbonic acid purifier for purifying carbonic acid in the gas filtered through foreign matter in the pre-treatment filter; and a post-treatment filter for filtering residual foreign matter in the gas purified through carbonic acid in the carbonic acid purifier.

[0019] The temperature of the gas cooled in the cooler and supplied to the grinding body of the jet mill is preferably controlled at -5°C to 10°C below zero.

[0020] A plurality of the coolers may be provided in series.

[0021] The material of the classifier disposed at the upper end of the grinding body of the air flow mill and separating particles according to particle size and the grinding base at the lower end of the grinding body are preferably stainless steel (SUS) series or ceramic.

[0022] Specific matters of other embodiments are included in the "Detailed Description" and "Drawings".

[0023] The advantages and / or features of the present invention, and methods for achieving them, can be found by reference to the accompanying Figure 1 This will become clear from various embodiments described in detail later.

[0024] However, the present invention is not limited to the compositions of the embodiments disclosed below, but may be implemented in a variety of different forms. The embodiments disclosed in this specification are only provided to complete the disclosure of the present invention and to fully inform the ordinary technicians in the technical field to which the present invention belongs of the scope of the present invention. It should be known that the claims of the present invention are only defined by the scope of each claim. Beneficial Effects

[0025] According to the solution of the aforementioned technical problem, the present invention has the following effects.

[0026] The effect of the present invention is that in order to cool the compressed gas that has been heated up through processes such as compression and dehumidification, a cooler can be added to control the temperature of the compressed gas to below 10°C, thereby making it easy to adjust the particle size of the sulfide solid electrolyte and prevent it from adhering to the grinding body.

[0027] In addition, the present invention has the effect that by further providing a carbonic acid purifier, carbonic acid can be prevented from acting as an impurity to reduce purity or from generating secondary or tertiary by-products and impairing the performance of the solid electrolyte. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a diagram showing a schematic configuration of a jet mill system with improved pulverization efficiency according to the present invention.

[0029] Figure 2 The diagram shows the feeding part of the jet mill system with improved pulverizing efficiency according to the present invention (Examples 1 to 6) and the feeding part of the jet mill system of the prior art (Comparative Examples 1 and 2). Description of Reference Numerals

[0030] 10: Compressor

[0031] 20: Dehumidifier

[0032] 30: Pre-processing filter

[0033] 40: Carbonate Purifier

[0034] 50: Post-processing filter

[0035] 60: Cooling machine

[0036] 70: Airflow Mill DETAILED DESCRIPTION

[0037] Hereinafter, a preferred embodiment of the air flow mill system with improved pulverizing efficiency of the present invention is described in detail with reference to the accompanying drawings. For reference, the terms and words used in this specification and claims should not be interpreted as limited to their conventional meanings or meanings in dictionaries, and the inventor should be based on the principle that the concepts of terms can be appropriately defined in order to explain his own invention in the best way, and use the meanings and concepts that are consistent with the technical ideas of the present invention for interpretation. In addition, the embodiments described in this specification and the configurations shown in the accompanying drawings are only the most preferred embodiments of the present invention and do not represent the entire technical ideas of the present invention. Therefore, it should be understood that there may be a variety of equivalents and modifications that can replace them when this application is submitted.

[0038] Figure 1 This is a diagram showing a schematic configuration of a jet mill system with improved pulverization efficiency according to the present invention.

[0039] The jet mill system with improved pulverizing efficiency of the present invention comprises: a compressor 10, a dehumidifier 20, a filter (a pre-treatment filter 30, a post-treatment filter 50), a cooler 60 and a jet mill 70, which are arranged in sequence.

[0040] The compressor 10 is used to compress the gas flowing in from the outside through the dust filter.

[0041] At this time, the gas is preferably any one of pure nitrogen, pure argon and air.

[0042] The dehumidifier 20 is used to remove moisture from the gas compressed in the compressor 10 .

[0043] The dehumidifier 20 as described above can dehumidify to a dew point of -90°C.

[0044] The filters (pre-processing filter 30 and post-processing filter 50) are used to filter foreign matter in the gas from which moisture is removed by the dehumidifier.

[0045] The cooler 60 can cool the gas filtered in the filter (pre-treatment filter 30, post-treatment filter 50) and supply the cooled gas to the grinding body of the jet mill 70, and a plurality of such coolers 60 can be provided in series.

[0046] As described above, the reason why a plurality of coolers 60 are provided and arranged in series is to efficiently cool the gas compressed in the compressor 10 to a desired temperature.

[0047] That is, since each cooler (cooling device) can cool at a different temperature and has a different cooling capacity, a plurality of coolers may be connected in series so that each cooler performs staged cooling.

[0048] For example, when two cooling machines are provided, the compressed gas may be cooled to 0° C. in the first cooling machine, and may be cooled to a desired sub-zero temperature in the second cooling machine.

[0049] At this time, the temperature of the gas cooled in the cooler 60 and supplied to the grinding body (grinding base) of the jet mill 70 is preferably controlled to be -5°C to 10°C below zero.

[0050] On the other hand, between the dehumidifier 20 and the cooler 60, there may be arranged in sequence: a pre-treatment filter 30 for filtering foreign matter in the compressed and dehumidified gas; a carbonic acid purifier 40 for purifying carbonic acid in the gas filtered through foreign matter in the pre-treatment filter 30 as described above; and a post-treatment filter 50 for filtering residual foreign matter in the gas purified through carbonic acid in the carbonic acid purifier 40.

[0051] As described above, in order to cool the compressed gas that has been heated up through processes such as compression and dehumidification, the present invention can add a cooler 60 so that the temperature of the compressed gas is controlled below 10°C (minus 5°C to 10°C), thereby making it easy to adjust the particle size of the sulfide solid electrolyte and prevent it from adhering to the grinding body.

[0052] In addition, the present invention may further provide a carbonic acid purifier 40 between the dehumidifier 20 and the cooler 60, thereby preventing carbonic acid from acting as an impurity to reduce purity or generating secondary or tertiary byproducts and hindering the performance of the solid electrolyte.

[0053] As can be seen from the following Table 1, the applicant conducted a comparative experiment on the production volume and PSA according to the temperature (grinding base temperature) of the gas (the gas is the gas supplied to the grinding base inside the grinding body of the air flow mill), wherein in this specification, air is used as the gas for the experiment.

[0054] The experimental process is as follows.

[0055] After setting up the cooler, stop starting the cooling equipment and supply compressed air to the jet mill through the bypass section.

[0056] At this time, the temperature of the compressed air was based on the temperature inside the grinding body 20 minutes after the compressed air was supplied to the equipment.

[0057] The data of Comparative Examples 1 and 2 were collected when the temperature of the compressed air was 23°C.

[0058] The temperature inside the grinding body was checked by starting the cooling device, and the same experiment as Comparative Examples 1 and 2 was performed by changing only the temperature (minus 5°C, 0°C, and 10°C, etc.) (the experiments are Examples 1 to 6).

[0059] After the experiment, the production volume and the accumulation degree in the inlet of the grinding body were confirmed and digitized.

[0060] [Table 1] Jet mill system with improved pulverization efficiency based on the present invention System production Amount and PSA (Example 1 to Implementation Example 6) and the production and PSA (comparison of the air jet mill system based on the prior art) Comparative Example 1 and Example 2); grinding matrix (Mill- Comparison of temperature differences of Base

[0061] The material of the classifier (classifier) ​​arranged at the upper end of the grinding body of the jet mill and separating particles according to particle size and the mill base (mill base) at the lower end of the grinding body is preferably stainless steel (Steel Use Stainless, SUS) series or ceramic.

[0062] Here, PSA stands for Particle Size Analysis, which is an analysis method for measuring the size of particles and calculating the relative proportion of particles.

[0063] That is, PSA is an analytical method for measuring the distribution of the particles by measuring the minimum and maximum sizes and the average value.

[0064] At this time, using the concept of cumulative distribution, the size values ​​that reach 10%, 50%, and 90% relative to the maximum value are called D10, D50, and D90, respectively, and the average value is called D mean , the maximum value is called D max .

[0065] On the other hand, as can be seen from Table 1 above, Example 3 has the best production yield and PSA.

[0066] That is, it can be seen that as the temperature of the mill base decreases, the production volume tends to increase, and the pulverization is smoothly achieved, resulting in a decrease in the size of the particles.

[0067] Figure 2 The diagram shows the feeding part of the jet mill system with improved pulverizing efficiency according to the present invention (Examples 1 to 6) and the feeding part of the jet mill system of the prior art (Comparative Examples 1 and 2).

[0068] After conducting the experiment according to the experimental conditions recorded in Table 1 above, Figure 2 As shown, it was confirmed that the raw material adhered to the feeding part of the grinding body of the jet mill.

[0069] In Comparative Examples 1 and 2 in which the temperature of the grinding base was 23° C., agglomerates occurred in which the raw materials adhered to the feed portion of the grinding body.

[0070] It can be seen from Examples 1 to 6 that as the temperature of the grinding base decreases, the phenomenon of raw materials adhering to the feed portion of the grinding body is significantly reduced.

[0071] [Table 2] According to the carbonation purifier operation switch (ON-OFF) Production volume, Comparison of electrical conductivity and ionic conductivity

[0072] For the evaluation of the ion conductivity retention rate, double vacuum packaging was performed using aluminum bags, and samples of Comparative Example 1 and Example 1 were collected under the same conditions.

[0073] In order to evaluate the ion conductivity retention rate, initial water contact is required, and therefore, the ion conductivity at 0 hr was measured under the temperature condition of -20°C at a dew point, and then the container was immediately sealed.

[0074] Meanwhile, sampling for measuring conductivity was performed under the temperature condition of dew point -60°C.

[0075] Finally, when the pulverization was performed without turning on the carbonation purifier, there was no significant difference in production volume between Comparative Example 1 and Example 1, but the ion conductivity of Example 1 decreased relative to Comparative Example 1, and the conductivity of Example 1 increased relative to Comparative Example 1.

[0076] Hereinafter, a method of verifying ion conductivity and changes in conductivity depending on whether carbonic acid is contained will be briefly described.

[0077] [Verification method 1] Based on whether the ion conductivity contains carbonic acid Degradation speed Comparison

[0078] The hydrolysis reaction of argyrodite is as follows.

[0079] Li6PS5Cl+6H2O→LiCl+Li3PO4+5H2S+2LiOH

[0080] When carbonic acid (CO2) is added thereto, the neutralization reaction formula is as follows.

[0081] 2LiOH+CO2→Li2CO3+H2O

[0082] When carbonic acid is present and exposed to moisture, more H2O is generated based on additional neutralization reactions and degrades it, thereby reducing ionic conductivity.

[0083] [Verification method 2] Changes in conductivity depending on whether carbonic acid is contained

[0084] The higher the conductivity of the electrolyte, the greater the possibility of self-discharge in the battery cell process. Therefore, the lower the conductivity, the better the physical properties.

[0085] When carbon is contained, the electrical conductivity increases, so whether carbonic acid is contained can be indirectly confirmed by analyzing the sample under the same conditions.

[0086] The present invention described above is not limited to the aforementioned embodiments and drawings, and various substitutions, deformations and changes can be made without departing from the technical concept of the present invention, which is obvious to ordinary technicians in the technical field to which the present invention belongs.

Claims

1. A jet mill system with improved pulverizing efficiency, characterized in that: include: A compressor for compressing gas flowing in from the outside; a dehumidifier for removing moisture from the gas compressed by the compressor; a filter for filtering foreign matter in the gas from which moisture is removed by the dehumidifier; and A cooler is used for cooling the gas filtered by the filter and supplying the cooled gas to the grinding body of the jet mill.

2. The jet mill system with improved pulverizing efficiency according to claim 1, characterized in that: The gas is any one of pure nitrogen, pure argon and air.

3. The jet mill system with improved pulverizing efficiency according to claim 1, characterized in that: The dehumidifier dehumidifies to a dew point level of minus 90°C.

4. The jet mill system with improved pulverizing efficiency according to claim 1, characterized in that: Between the dehumidifier and the cooling machine are arranged in sequence: a pre-treatment filter for filtering foreign matter in the compressed and dehumidified gas; a carbonic acid purifier for purifying carbonic acid in the gas filtered by foreign matter in the pretreatment filter; as well as The post-processing filter filters residual foreign matter in the gas purified by carbonic acid in the carbonic acid purifier.

5. The jet mill system with improved pulverizing efficiency according to claim 4, characterized in that: The temperature of the gas cooled in the cooler and supplied to the grinding body of the jet mill is controlled to be minus 5°C to 10°C.

6. The jet mill system with improved pulverizing efficiency according to claim 5, characterized in that: A plurality of the coolers are arranged in series.

7. The jet mill system with improved pulverizing efficiency according to claim 1, characterized in that: The material of the classifier arranged at the upper end of the grinding body of the air flow mill and separating particles according to particle size and the grinding base at the lower end of the grinding body are stainless steel series or ceramics.

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