Ion-conductive ceramic and method for producing same

Abstract

The invention relates to a ceramic solid electrolyte for improving safety and a synthesis method thereof. The ceramic solid electrolyte is a core structural element of an all-solid-state lithium secondary battery. The invention relates to a compound represented by the chemical formula Li1 + xAlxX2-xP3O12 (X is Zr, Si, Sn or Y, 0lt; xlt; (2) or Li1 + xZr2XxP3-xO12 (X = Si, Sn, Ge or Y, and x is greater than or equal to 1.5 and less than or equal to 2.3). The present invention also relates to a method for producing the oxide-based conductive ceramic having the novel NASICON structure.

Description

Technical Field

[0001] The present invention relates to an oxide-based ceramic having a NASICON structure with lithium ion conductivity. The lithium ion conductive ceramic of the present invention is a substance with a novel chemical structure and has excellent ionic conductivity. The present invention also relates to a method for synthesizing the above novel ceramic. According to a preferred synthesis method of the present invention, water is used as a solvent, and raw material substances are mixed and the above novel ceramic is synthesized by a rotary concentration process or a spray drying process. The ceramic manufactured in this way becomes ceramic solid electrolyte particles with spherical particles and uniform distribution. When the ceramic particles of the present invention are made into an electrolyte and applied to a battery, excellent electrochemical properties are exhibited. Background Art

[0002] The lithium secondary battery market is spreading not only to small IT devices but also to medium and large markets such as electric vehicles and ESS systems. Existing lithium secondary batteries use liquid electrolytes. However, encapsulating and enlarging using an explosive liquid electrolyte is like manufacturing a powder magazine that may explode at any time. In addition, for a lithium secondary battery using a liquid electrolyte, there is a risk of explosion when the temperature rises, so expensive safety devices such as a vent cap or a PTC (positive temperature coefficient) device are required. The use of such safety devices has become a reason for reducing the energy density of lithium secondary batteries and increasing the battery manufacturing cost. Therefore, in terms of the energy density and manufacturing cost of secondary batteries, the use of expensive safety devices is disadvantageous for both small-capacity batteries used in portable electronic devices and large-capacity batteries such as the power source of electric vehicles.

[0003] Therefore, research and development for manufacturing more excellent lithium secondary batteries are being actively carried out, and various technologies for solving the problems of existing lithium secondary batteries have been proposed. Among them, all-solid-state batteries have received much attention. All-solid-state batteries do not use the liquid electrolyte and polymer separator used in existing lithium secondary batteries, but by using a solid-state electrolyte, the solid-state electrolyte has the functions of the existing liquid electrolyte and separator.

[0004] Using solid electrolytes can eliminate the risks of fire and explosion associated with existing liquid electrolytes and increase the energy density of batteries by reducing the space within the battery. Solid electrolytes are classified into polymer solid electrolytes and ceramic solid electrolytes. Polymer solid electrolytes are difficult to manufacture and process, presenting numerous difficulties in commercialization. Polymer solid electrolytes also have the problem of relatively low ionic conductivity. To improve the low ionic conductivity, polymer gel electrolytes with added liquid electrolytes are also under research. However, polymer gel electrolytes contain a relatively large amount of liquid electrolytes, so they have the drawback of inevitably exhibiting the disadvantages of liquid electrolytes. Therefore, recently, the attention on ceramic solid electrolytes has been increasing.

[0005] Lithium-ion conductive ceramic electrolytes can be broadly classified into sulfide-based and oxide-based. Compared with oxide-based solid electrolytes, sulfide-based solid electrolytes are relatively easy to synthesize, have toughness, so they do not require high heat treatment during processing, and exhibit relatively high conductivity. For example, Li 3.25 Ge 0.25 P 0.75 S4 exhibits an ionic conductivity of 2.2 mS / cm. LGPS (Li 10 GeP2S 12 ) exhibits an ionic conductivity of 12 mS / cm. However, sulfide-based solid electrolytes have a fatal drawback, namely, they have a strong odor, produce side reactions in the cathode part, and are unstable in air and water. Therefore, the attention on stable oxide-based solid electrolytes is increasing. Representative oxide-based solid electrolytes include LATP (Li 1+x Al x Ti 2-x (PO4)3)(0 < x < 2), LLZO (Li7La3Zr2O 12 ) and so on. LATP and LLZO have excellent ionic conductivity and are relatively stable in the atmosphere, so they are relatively easy to commercialize. However, these oxide-based solid electrolytes have Ti that undergoes a reduction reaction in the cathode part, or have seven lithiums, are unstable in air and produce gas. In addition, most of these are manufactured by the solid-state method, so the particles are not uniform, and there are significant differences in crystallinity depending on the heat treatment temperature.

[0006] Therefore, an ion-conductive ceramic with a new chemical structure is needed. It is necessary to develop a stable oxide-based ceramic in air as a new ceramic. Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] Due to LATP (Li1+x Al x Ti 2-x (PO4)3) or LLZO (Li7La3Zr2O with a garnet structure 12 ) has excellent ionic conductivity and is therefore mainly used as an existing oxide-based ceramic solid electrolyte. However, these have the following problems: having Ti in the chemical structure composition, thus causing a reduction reaction in the cathode part, or having seven lithium elements, so it has a relatively large reactivity with air and is unstable in the atmosphere. The object of the present invention is to provide a new oxide-based conductive ceramic having excellent ionic conductivity and being stable in air. In addition, the object of the present invention is to manufacture a ceramic solid electrolyte with a uniform distribution and shape of particles, a spherical particle shape, and excellent crystallinity by improving the synthesis method of the existing ceramic solid electrolyte.

[0009] Solutions to the problems

[0010] In order to solve the problems of the existing ceramic solid electrolyte, it aims to provide an NASICON-structured oxide-based conductive ceramic and its manufacturing method that do not contain Ti in the structural composition, contain only 1.3 to 2.3 lithium elements, have excellent ionic conductivity, and are relatively stable in air. The ceramic with the new structure can be manufactured by the existing solid-state method. Using water as a solvent, the raw material substances are mixed and ball-milled. When manufacturing oxide-based conductive ceramic particles by a new method applying the rotary concentration method or the spray method, ceramic particles with a uniform spherical shape and a uniform particle distribution can be obtained. When the oxide-based ceramic particles manufactured in this way are made into an electrolyte and applied to a battery, excellent electrochemical properties are exhibited.

[0011] Advantages of the invention

[0012] According to the present invention, an NASICON-structured oxide-based conductive ceramic can be provided, which has excellent electrochemical reactions, is relatively stable in the atmosphere, and has a high ionic conductivity.

[0013] According to the present invention, a high-performance ceramic electrolyte with a relatively uniform shape and distribution of particles can be manufactured.

[0014] According to the present invention, high-performance ceramic particles with a spherical particle morphology and a uniform distribution can be manufactured. Description of the drawings

[0015] Figure 1 is an NASICON-structured oxide-based conductive ceramic Li synthesized by the conventional solid-state method 1+x Al x Si 2-x P3O 12 SEM image of (x = 0.3).

[0016] Figure 2 is an NASICON - structured oxide - based conductive ceramic Li 1+x Zr2Si x P 3- x O 12 SEM image of (x = 2).

[0017] Figure 3 is an NASICON - structured oxide - based conductive ceramic Li 1+x Al x Si 2-x P3O 12 XRD pattern of (x = 0.3).

[0018] Figure 4 is an NASICON - structured oxide - based conductive ceramic Li 1+x Al x Si 2-x P3O 12 SEM image of (x = 0.3) particles.

[0019] Figure 5 is an NASICON - structured oxide - based conductive ceramic Li that varies with temperature 1+x Al x Si 2-x P3O 12 Ionic conductivity of (x = 0.3).

[0020] Figure 6 is an NASICON - structured oxide - based conductive ceramic Li 1+x Al x Sn 2-x P3O 12 XRD pattern of (x = 0.5).

[0021] Figure 7 is an NASICON - structured oxide - based conductive ceramic Li 1+x Al x Sn 2-x P3O 12 SEM image of (x = 0.5) particles.

[0022] Figure 8 is an NASICON - structured oxide - based conductive ceramic Li that varies with temperature 1+x Al x Sn 2-x P3O 12Ionic conductivity at (x = 0.5).

[0023] Figure 9 is the NASICON - structured oxide - based conductive ceramic Li 1+x Zr2Si x P 3-x O 12 (x = 2) and Li 1+ x Zr2Sn x P 3-x O 12 XRD pattern of (x = 2).

[0024] Figure 10 is the NASICON - structured oxide - based conductive ceramic Li 1+x Zr2Si x P 3-x O 12 SEM image of the particles of (x = 2).

[0025] Figure 11 is the NASICON - structured oxide - based conductive ceramic Li 1+x Zr2Si x P 3-x O 12 Ionic conductivity of (x = 2).

[0026] Figure 12 is the NASICON - structured oxide - based conductive ceramic Li 1+x Zr2Sn x P 3-x O 12 SEM image of the particles of (x = 2).

[0027] Figure 13 is the NASICON - structured ceramic solid electrolyte Li 1.3 Al 0.3 Si 1.7 P3O 12 image of the particles.

[0028] Figure 14 is the NASICON - structured ceramic solid electrolyte Li 1.3 Al 0.3 Si 1.7 P3O 12 image of the particles. Specific embodiments

[0029] A detailed description of the specific content of the present invention is provided. However, the specific content is presented by way of example through an embodiment of the present invention. The present invention is not limited to the following description, and the present invention is only defined by the claims.

[0030] The oxide-based conductive ceramic with a novel NASICON structure according to the present invention has a structure shown in Chemical Formula 1 below.

[0031] [Chemical Formula 1]

[0032] Li 1+x Al x X 2-x P3O 12

[0033] Wherein, X = Zr, Si, Sn or Y, and 0 < x < 2.

[0034] The oxide-based conductive ceramic with a novel NASICON structure according to the present invention has a structure shown in Chemical Formula 2 below.

[0035] [Chemical Formula 2]

[0036] Li 1+x Zr2X x P 3-x O 12

[0037] Wherein, X is Si, Sn, Ge or Y, and 1.5 ≤ x ≤ 2.3.

[0038] In one embodiment of the present invention, the raw material substances of the ceramic solid electrolyte are mixed, and after sufficient ball milling and mixing, the conductive ceramic of Chemical Formula 1 is synthesized through primary heat treatment and secondary heat treatment. The primary heat treatment can be calcination of the ceramic particles, and the secondary heat treatment can be firing of the ceramic particles.

[0039] In one embodiment of the present invention, using water as a solvent, the raw material substances of the ceramic solid electrolyte are mixed, and after sufficient ball milling and mixing in a solution state, the ball-milled mixture is dried in a dryer, and the conductive ceramic of Chemical Formula 1 is synthesized through primary heat treatment and secondary heat treatment. The primary heat treatment can be calcination of the ceramic particles, and the secondary heat treatment can be firing of the ceramic particles.

[0040] The ball milling speed can be 150 to 350 rpm, can be 200 to 350 rpm, can be 250 to 350 rpm, or can be 250 to 300 rpm.

[0041] The ball milling mixing time can be from 12 hours to 48 hours, can be from 12 hours to 36 hours, can be from 24 hours to 36 hours.

[0042] The drying time in the dryer is from 12 hours to 36 hours. Preferably, it can be from 18 hours to 24 hours. The drying temperature can be from 60°C to 100°C. Preferably, it can be from 70°C to 80°C.

[0043] The temperature of the first heat treatment can be from 300°C to 500°C, preferably from 350°C to 450°C. The temperature of the second heat treatment can be from 800°C to 1200°C, preferably from 850°C to 1100°C, more preferably from 900°C to 1100°C. According to the substance and conditions, preferably, it can be from 800°C to 1000°C, and preferably, it can be from 900°C to 1000°C.

[0044] The time of the first heat treatment and the second heat treatment can be from 2 hours to 12 hours, 2 hours to 11 hours, 2 hours to 10 hours, 2 hours to 9 hours, 2 hours to 8 hours, 2 hours to 7 hours, 2 hours to 6 hours, 2 hours to 5 hours, 2 hours to 4 hours, 3 hours to 12 hours, 3 hours to 11 hours, 3 hours to 10 hours, 3 hours to 9 hours, 3 hours to 8 hours, 3 hours to 7 hours, 3 hours to 6 hours, 3 hours to 5 hours, 3 hours to 4 hours, 4 hours to 12 hours, 4 hours to 11 hours, 4 hours to 10 hours, 4 hours to 9 hours, 4 hours to 8 hours, 4 hours to 7 hours, 4 hours to 6 hours, 4 hours to 5 hours, 5 hours to 12 hours, 5 hours to 11 hours, 5 hours to 10 hours, 5 hours to 9 hours, 5 hours to 8 hours, 5 hours to 7 hours, 5 hours to 6 hours, 6 hours to 12 hours, 6 hours to 11 hours, 6 hours to 10 hours, 6 hours to 9 hours, 6 hours to 8 hours, 6 hours to 7 hours.

[0045] In one embodiment of the present invention, after mixing the raw material substances of the ceramic solid electrolyte and fully performing ball milling mixing, the conductive ceramic of Chemical Formula 2 is synthesized through the first heat treatment and the second heat treatment. The first heat treatment can calcine the ceramic particles, and the second heat treatment can fire the ceramic particles.

[0046] In one embodiment of the present invention, using water as a solvent, the raw material substances of the ceramic solid electrolyte are mixed, and after fully performing ball milling mixing in a solution state, the ball milled mixture is dried in a dryer, and the conductive ceramic of Chemical Formula 2 is synthesized through the first heat treatment and the second heat treatment. The first heat treatment can be to calcine the ceramic particles, and the second heat treatment can be to fire the ceramic particles.

[0047] The ball milling mixing time can be from 8 hours to 48 hours, from 8 hours to 36 hours, from 8 hours to 24 hours, from 10 hours to 24 hours, or from 10 hours to 18 hours.

[0048] The drying time in the dryer can be from 12 hours to 36 hours, preferably from 18 hours to 24 hours, and the drying temperature can be from 60°C to 100°C, preferably from 70°C to 80°C.

[0049] The temperature of the first heat treatment can be from 300°C to 500°C, preferably from 350°C to 450°C. The temperature of the second heat treatment can be from 800°C to 1200°C, preferably from 850°C to 1100°C, more preferably from 900°C to 1100°C. Depending on the substance and conditions, preferably, it can be from 800°C to 1000°C, and preferably, it can be from 900°C to 1000°C.

[0050] The time of the first heat treatment and the second heat treatment can be from 2 hours to 13 hours, from 2 hours to 12 hours, from 2 hours to 11 hours, from 2 hours to 10 hours, from 2 hours to 9 hours, from 2 hours to 8 hours, from 2 hours to 7 hours, from 2 hours to 6 hours, from 2 hours to 5 hours, from 2 hours to 4 hours, from 3 hours to 13 hours, from 3 hours to 12 hours, from 3 hours to 11 hours, from 3 hours to 10 hours, from 3 hours to 9 hours, from 3 hours to 8 hours, from 3 hours to 7 hours, from 3 hours to 6 hours, from 3 hours to 5 hours, from 3 hours to 4 hours, from 4 hours to 13 hours, from 4 hours to 12 hours, from 4 hours to 11 hours, from 4 hours to 10 hours, from 4 hours to 9 hours, from 4 hours to 8 hours, from 4 hours to 7 hours, from 4 hours to 6 hours, from 4 hours to 5 hours, from 5 hours to 13 hours, from 5 hours to 12 hours, from 5 hours to 11 hours, from 5 hours to 10 hours, from 5 hours to 9 hours, from 5 hours to 8 hours, from 5 hours to 7 hours, from 5 hours to 6 hours, from 6 hours to 13 hours, from 6 hours to 12 hours, from 6 hours to 11 hours, from 6 hours to 10 hours, from 6 hours to 9 hours, from 6 hours to 8 hours, from 6 hours to 7 hours, from 5 hours to 13 hours, from 5 hours to 12 hours, from 5 hours to 11 hours, from 5 hours to 10 hours, from 5 hours to 9 hours, from 5 hours to 8 hours, from 5 hours to 7 hours, from 5 hours to 6 hours, from 6 hours to 13 hours, from 6 hours to 12 hours, from 6 hours to 11 hours, from 6 hours to 10 hours, from 6 hours to 9 hours, from 6 hours to 8 hours, from 6 hours to 7 hours.

[0051] In one embodiment of the present invention, after performing the above ball milling and mixing, primary drying is carried out by adding a rotary concentration or spray drying step. After secondary drying at 60 °C to 100 °C, preferably at 60 °C to 80 °C, more preferably at 70 °C to 80 °C, the oxide-based conductive ceramic of Chemical Formula 1 or Chemical Formula 2 can be manufactured by performing the above primary heat treatment and the above secondary heat treatment. The temperature of the rotary concentration process can be 60 °C to 100 °C, and preferably 70 °C to 80 °C. The temperature of the spray drying process can be 80 °C to 300 °C, preferably 100 °C to 200 °C.

[0052] Best Mode

[0053] Example 1

[0054] Synthetic chemical composition is Li 1+x Al x Si 2-x P3O 12 (x = 0.3) Oxide-based conductive ceramic with NASICON structure

[0055] After calculating LiCl, Al(NO3)3·9H2O, NH4H2PO4, and C8H 20 O4Si according to chemical equivalence, each is mixed in a molar ratio of 1.3:0.3:3:1.7. Then, zirconia balls with diameters of 5 mm and 10 mm are prepared in a ratio of 2:1 and placed in a prepared 500 ml container so that the volume ratio of the mixed sample to the zirconia balls is 1:1. The rotation speed of the ball milling is 200 - 300 RPM, and ball milling is carried out for 24 hours. After 24 hours of ball milling and mixing, the zirconia balls are removed. Then, a primary heat treatment is carried out at 400 °C for 3 hours. After grinding and pulverizing the heat-treated powder in a mortar, a secondary heat treatment is carried out at 900 °C for 4 hours to synthesize a chemical composition of Li 1+x Al x Si 2-x P3O 12 (x = 0.3) Oxide-based conductive ceramic with NASICON structure. Figure 1 The SEM image of the conductive ceramic particles synthesized in Example 1 is shown.

[0056] Example 2

[0057] Synthetic chemical composition is Li 1+x Zr2Si x P 3-x O 12 (x = 2) Oxide-based conductive ceramic with NASICON structure

[0058] After calculating Li3PO4, SiO2, and ZrO2 according to chemical equivalents, each was mixed in a molar ratio of 1:2:2. Then, zirconia balls with diameters of 5 mm and 10 mm were prepared in a ratio of 2:1 and placed in a prepared 500-ml container so that the volume ratio of the mixed sample to the zirconia balls was 1:1. The rotation speed of ball milling was 200 - 300 RPM, and ball milling was carried out for 10 hours. After 10 hours of ball milling and mixing, the zirconia balls were removed. Then, a heat treatment was carried out at 400 °C for 5 hours. After grinding and pulverizing the heat-treated powder in a mortar, a secondary heat treatment was carried out at 1100 °C for 12 hours to synthesize an oxide-based conductive ceramic with a chemical composition of Li 1+x Zr2Si x P 3-x O 12 (x = 2) NASICON-structured oxide-based conductive ceramic. Figure 2 The SEM image of the conductive ceramic particles synthesized in Example 2 is shown.

[0059] Example 3

[0060] Synthesize an oxide-based conductive ceramic with a chemical composition of Li 1+x Al x Si 2-x P3O 12 (x = 0.3) NASICON-structured oxide-based conductive ceramic

[0061] After calculating LiCl, Al(NO3)3·9H2O, NH4H2PO4, and C8H 20 O4Si according to chemical equivalents, each was placed in 500 ml of distilled water in a molar ratio of 1.3:0.3:3:1.7. Then, zirconia balls with diameters of 5 mm and 10 mm were prepared in a ratio of 2:1 and placed in a prepared 500-ml container so that the volume ratio of the mixed sample to the zirconia balls was 1:1. The rotation speed of ball milling was 200 - 300 RPM, and ball milling was carried out for 24 hours. After 24 hours of ball milling and mixing, the zirconia balls were removed and dried at 80 °C for 12 hours. Then, a heat treatment was carried out at 400 °C for 3 hours. After grinding and pulverizing the heat-treated powder in a mortar, a secondary heat treatment was carried out at 900 °C for 4 hours to synthesize an oxide-based conductive ceramic with a chemical composition of Li 1+ x Al x Si 2-x P3O 12 (x = 0.3) NASICON-structured oxide-based conductive ceramic.

[0062] Figure 3 The XRD pattern of the conductive ceramic synthesized in this way is shown. Figure 4The SEM image of the conductive ceramic particles synthesized in Example 3 is shown. Figure 5 The ionic conductivity of the conductive ceramic synthesized in Example 3, which changes with temperature, is shown.

[0063] Li 1+x Al x Si 2-x P3O 12 (x = 0.3) The conductive ceramic has an ionic conductivity of 1.08×10 -4 S / cm at 30 °C, and the average particle size is 4 μm.

[0064] Example 4

[0065] Synthesize an oxide-based conductive ceramic with a NASICON structure having a chemical composition of Li 1+x Al x Sn 2-x P3O 12 (x = 0.5)

[0066] After calculating LiCl, Al(NO3)3·9H2O, NH4H2PO4, and SnO2 according to chemical equivalents, each is placed in 500 ml of distilled water in a molar ratio of 1.5:0.5:3:1.5. Then, zirconia balls with diameters of 5 mm and 10 mm are prepared in a ratio of 2:1 and placed in the prepared 500 ml container so that the volume ratio of the mixed sample to the zirconia balls is 1:1. The rotation speed of the ball milling is 200 - 300 RPM, and ball milling is carried out for 24 hours. After 24 hours of ball milling and mixing, the zirconia balls are removed and dried at 80 °C for 12 hours. Then, a primary heat treatment is carried out at 400 °C for 3 hours. After grinding and pulverizing the heat-treated powder in a mortar, a secondary heat treatment is carried out at 900 °C for 4 hours to synthesize an oxide-based conductive ceramic with a NASICON structure having a chemical composition of Li 1+x Al x Sn 2- x P3O 12 (x = 0.5).

[0067] Figure 6 The XRD pattern of the conductive ceramic synthesized in this way is shown. Figure 7 The SEM image of the conductive ceramic particles synthesized in Example 4 is shown. Figure 8 The ionic conductivity of the conductive ceramic synthesized in Example 4, which changes with temperature, is shown.

[0068] Li 1+x Al x Sn 2-x P3O 12(x = 0.5) The conductive ceramic has an ionic conductivity of 6.07×10 -4 S / cm at 30 °C, and the average particle size is 3 μm.

[0069] Example 5

[0070] The synthetic chemical composition is Li 1+x Zr2Si x P 3-x O 12 (x = 2) Oxide-based conductive ceramic with a NASICON structure

[0071] After calculating Li3PO4, SiO2, and ZrO2 according to chemical equivalence, 1:2:2 moles of each were placed in 500 ml of distilled water. Then, zirconia balls with diameters of 5 mm and 10 mm were prepared in a ratio of 2:1 and placed in the prepared 500 ml container, so that the volume ratio of the mixed sample to the zirconia balls was 1:1. The rotation speed of the ball milling was 200 - 300 RPM, and ball milling was carried out for 10 hours. After 10 hours of ball milling and mixing, the zirconia balls were removed and dried at 80 °C for 12 hours. Then, a primary heat treatment was carried out at 400 °C for 5 hours. After grinding and pulverizing the heat-treated powder in a mortar, a secondary heat treatment was carried out at 1100 °C for 12 hours to synthesize the oxide-based conductive ceramic with a NASICON structure having a chemical composition of Li 1+x Zr2Si x P 3-x O 12 (x = 2).

[0072] Figure 9 The XRD pattern of the conductive ceramic synthesized in this way is shown. Figure 10 The SEM image of the conductive ceramic particles synthesized in Example 5 is shown. Figure 11 The ionic conductivity of the conductive ceramic synthesized in Example 5 as a function of temperature is shown.

[0073] Li 1+x Zr2Si x P 3-x O 12 (x = 2) The conductive ceramic has an ionic conductivity of 7.6×10 -4 S / cm at 30 °C, and the average particle size is 4 μm.

[0074] Example 6

[0075] The synthetic chemical composition is Li 1+x Zr2Sn x P 3-x O 12NASICON-structured oxide-based conductive ceramic with (x = 2)

[0076] After calculating Li3PO4, SnO2, and ZrO2 according to chemical equivalents, each was placed in 500 ml of distilled water in a molar ratio of 1:2:2. Then, zirconia balls with diameters of 5 mm and 10 mm were prepared in a ratio of 2:1 and placed in the prepared 500 ml container so that the volume ratio of the mixed sample to the zirconia balls was 1:1. The rotation speed of the ball milling was 200 - 300 RPM, and ball milling was carried out for 10 hours. After 10 hours of ball milling and mixing, the zirconia balls were removed and dried at 80 °C for 12 hours. Then, a heat treatment was carried out at 400 °C for 5 hours once. After grinding and pulverizing the heat-treated powder in a mortar, a secondary heat treatment was carried out at 1100 °C for 12 hours to synthesize a chemical composition of Li 1+x Zr2Sn x P 3-x O 12 NASICON-structured oxide-based conductive ceramic with (x = 2).

[0077] Figure 9 The XRD pattern of the conductive ceramic synthesized in this way is shown.

[0078] Li 1+x Zr2Sn x P 3-x O 12 The (x = 2) conductive ceramic has an ionic conductivity of 4.8×10 -4 S / cm at 30 °C, and the average particle size is 5 μm.

[0079] Example 7

[0080] Synthesize a NASICON-structured oxide-based conductive ceramic with a chemical composition of Li 1.3 Al 0.3 Si 1.7 P3O 12

[0081] ​After calculating LiCl, Al(NO3)3·9H2O, NH4H2PO4, and SiO2 according to chemical equivalents, each was placed in 500 ml of distilled water at a ratio of 1.3:0.3:3:1.7 moles. Then, zirconia balls with diameters of 5 mm and 10 mm were prepared in a ratio of 2:1 and placed in the prepared 500-ml container so that the volume ratio of the mixed sample to the zirconia balls was 1:1. The rotation speed of the ball milling was 200 - 300 RPM, and ball milling was carried out for 24 hours. After removing the zirconia balls, primary drying was carried out by rotary concentration of the ball-milled sample at 80°C for 6 hours. After placing it in an evaporating dish, secondary drying was fully carried out at 80°C for 24 hours. Then, the dried sample was ground into a powder form using a mortar and subjected to heat treatment. To calcine the sample, the first heat treatment was to raise the temperature from room temperature to 400°C, then carry out heat treatment for 4 hours, and naturally cool to below 100°C. To sinter the sample, the second heat treatment was carried out at 1000°C for 4 hours, and then chemical composition Li 1.3 Al 0.3 Si 1.7 P3O 12 of NASICON-structured oxide-based conductive ceramics.

[0082] Figure 13 Figures showing the particles of the conductive ceramics synthesized in this way are shown in Figure 13 As shown in

[0083] Example 8

[0084] Synthesize oxide-based conductive ceramics with a chemical composition of Li 1.3 Al 0.3 Si 1.7 P3O 12 with a NASICON structure

[0085] After calculating the chemical equivalents of LiCl, Al(NO3)3·9H2O, NH4H2PO4, and SiO2, each was placed in 500 ml of distilled water at a ratio of 1.3:0.3:3:1.7 moles. Then, zirconia balls with diameters of 5 mm and 10 mm were prepared in a ratio of 2:1 and placed in the prepared 500 ml container so that the volume ratio of the mixed sample to the zirconia balls was 1:1. The rotation speed of the ball milling was 200 - 300 RPM, and ball milling was carried out for 24 hours. After removing the zirconia balls, the ball-milled sample was subjected to primary drying for 24 hours by spray method at 170 °C, placed in an evaporating dish, and then subjected to secondary drying for 24 hours at 80 °C. Then, the dried sample was ground into a powder form using a mortar and subjected to heat treatment. For calcining the sample, the first heat treatment was to raise the temperature from room temperature to 400 °C, then carry out heat treatment for 4 hours, and naturally cool to below 100 °C. For firing the sample, the second heat treatment was carried out at 1000 °C for 4 hours. After that, the chemical composition of Li 1.3 Al 0.3 Si 1.7 P3O 12 was obtained for the NASICON-structured oxide-based conductive ceramic.

[0086] Figure 12 Figures showing the particles of the conductive ceramic synthesized in this way are shown in Figure 14 As shown, the ceramic synthesized by increasing the spray process has round and very evenly distributed particles. The average particle size is 3 μm.

Claims

1. An oxide-based conductive ceramic with a NASICON structure, characterized in that the oxide-based conductive ceramic has the following Chemical Formula 1, [Chemical Formula 1] Li 1+x Al x X 2-x P3O 12 wherein X is Zr, Si, Sn or Y, and 0 < x < 2.

2. An oxide-based conductive ceramic with a NASICON structure, characterized in that the oxide-based conductive ceramic has the following Chemical Formula 2, [Chemical Formula 2] Li 1+x Zr2X x P 3-x O 12 wherein X = Si, Ge or Y, and 1.5 ≤ x ≤ 2.

3.

3. A method for synthesizing an oxide-based conductive ceramic with a NASICON structure, characterized in that after mixing the raw materials of the ceramic solid electrolyte, ball milling is carried out, and an oxide-based conductive ceramic with a NASICON structure of the following Chemical Formula 1 or Chemical Formula 2 is synthesized by performing a primary heat treatment at 300 °C to 500 °C and a secondary heat treatment at 800 °C to 1200 °C, [Chemical Formula 1] Li 1+x Al x X 2-x P3O 12 wherein X is Zr, Si, Sn or Y, and 0 < x < 2, [Chemical Formula 2] Li 1+x Zr2X x P 3-x O 12 wherein X = Si, Ge or Y, and 1.5 ≤ x ≤ 2.

3.

4. A method for synthesizing an oxide-based conductive ceramic with a NASICON structure, characterized in that the raw materials of the ceramic solid electrolyte are placed in water, ball milling is carried out, and after drying the ball-milled mixture in a dryer, an oxide-based conductive ceramic with a NASICON structure of the following Chemical Formula 1 or Chemical Formula 2 is synthesized by performing a primary heat treatment at 300 °C to 500 °C and a secondary heat treatment at 800 °C to 1200 °C, [Chemical Formula 1] Li 1+x Al x X 2-x P3O 12 wherein X is Zr, Si, Sn or Y, and 0 < x < 2, [Chemical Formula 2] Li 1+x Zr2X x P 3-x O 12 wherein X = Si, Ge or Y, and 1.5 ≤ x ≤ 2.

3.

5. A method for synthesizing an oxide-based conductive ceramic with a NASICON structure, characterized in that the raw materials of the ceramic solid electrolyte are placed in water, ball milling is carried out, the ball-milled mixture is subjected to primary drying by rotary concentration or spraying, then secondary drying of the ball-milled mixture is carried out in a dryer, and an oxide-based conductive ceramic with a NASICON structure of the following Chemical Formula 1 or Chemical Formula 2 is synthesized by performing a primary heat treatment at 300 °C to 500 °C and then a secondary heat treatment at 800 °C to 1200 °C, [Chemical Formula 1] Li 1+x Al x X 2-x P3O 12 wherein X is Zr, Si, Sn or Y, and 0 < x < 2, [Chemical Formula 2] Li 1+x Zr2X x P 3-x O 12 wherein X = Si, Ge or Y, and 1.5 ≤ x ≤ 2.3.

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