Application of NTC material in preparation of electrode material
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHAOQING JINLONGBAO ELECTRONIC CO LTD
- Filing Date
- 2024-01-09
- Publication Date
- 2026-06-26
AI Technical Summary
Currently, NTC thermistors rely on imports, which are costly and make it difficult to provide alternative materials with comparable quality to the Japanese Shibaura 1K/4537 single-ended glass-sealed resistor.
An NTC material, MnaCobNicFedAl1-abc-dO4, was prepared by co-precipitation reaction of a mixed metal salt solution, oxalic acid solution, and ammonia water. After aging, the material was calcined, granulated, pressed, and sintered to obtain the electrode material.
The prepared NTC material is used for gold and silver electrodes, exhibiting excellent electrical properties similar to those of the Japanese 1K/4537 product. It also shows good stability after aging at 300℃ for 1000 hours, with low cost and high reproducibility.
Smart Images
Figure CN118955094B_ABST
Abstract
Description
[0001] This application is a divisional application. The original application number is 202410032655.0, the application date is January 9, 2024, and the invention title is "An NTC material and its preparation method". Technical Field
[0002] This invention relates to the field of thermistor ceramic materials technology, and in particular to the application of an NTC material in the preparation of electrode materials. Background Technology
[0003] Negative temperature coefficient (NTC) thermistors are temperature-sensitive material components made of semiconductor ceramic materials. The resistance of NTC thermistors decreases exponentially with increasing temperature, offering advantages such as high temperature sensitivity, small size, fast response, low cost, and good interchangeability. They are widely used in temperature measurement, temperature control, and compensation. With the development of science and technology, the application fields of NTC thermistors are expanding, and the performance requirements for thermistors are becoming increasingly stringent. Currently, NTC thermistors still mainly rely on imports. Among them, NTC thermistors represented by the Japanese Shibaura 1K / 4537 single-ended glass-sealed resistor are characterized by high quality and good stability, and have dominated the market for a long time, resulting in high operating costs. Therefore, providing an NTC thermistor with superior performance comparable to the Japanese Shibaura 1K / 4537 single-ended glass-sealed resistor is of great significance. Summary of the Invention
[0004] The purpose of this invention is to overcome the problems existing in the prior art and provide an NTC material and its preparation method.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0006] This invention provides an NTC material, wherein the NTC material is Mn a Co b Ni c Fe d Al 1-a-b-c-d O4; where 0.50≤a≤0.55, 0.060≤b≤0.065, 0.20≤c≤0.25, and 0.025≤d≤0.030.
[0007] The present invention also provides a method for preparing the NTC material, comprising the following steps:
[0008] (1) Manganese sulfate, cobalt sulfate, nickel sulfate, ferrous sulfate, aluminum sulfate and water are mixed to obtain a metal salt solution;
[0009] (2) The metal salt solution, oxalic acid solution and ammonia water were mixed and subjected to co-precipitation and aging in sequence to obtain the precursor;
[0010] (3) The precursor is calcined to obtain ceramic powder;
[0011] (4) The ceramic powder and polyvinyl alcohol solution are mixed and granulated to obtain granulated powder;
[0012] (5) The granulated powder is pressed and sintered in sequence to obtain the NTC material.
[0013] Preferably, the concentration of metal ions in the metal salt solution in step (1) is 1-2 mol / L;
[0014] The concentration of the oxalic acid solution in step (2) is 1-2 mol / L;
[0015] The molar ratio of metal ions in the metal salt solution in step (1) to oxalic acid in the oxalic acid solution in step (2) is 1:1.5-2.
[0016] Preferably, the mass fraction of the ammonia water in step (2) is 25-28%;
[0017] The pH of the solution obtained by mixing in step (2) is 3.5 to 4.
[0018] Preferably, the temperature of the coprecipitation reaction in step (2) is 45-55°C, and the time of the coprecipitation reaction is 1-3 hours.
[0019] The aging temperature in step (2) is 20-30°C, and the aging time is 12-24 hours.
[0020] Preferably, the calcination temperature in step (3) is 650–850°C and the calcination time is 2–5 h.
[0021] Preferably, the polyvinyl alcohol solution in step (4) has a mass fraction of 3.5-4.5%;
[0022] The mass ratio of ceramic powder to polyvinyl alcohol solution in step (4) is 90-95:5-10.
[0023] Preferably, the pressing pressure in step (5) is 8 to 300 MPa.
[0024] Preferably, the intermediate temperature of sintering in step (5) is 400-550°C;
[0025] The heating rate from room temperature to the intermediate sintering temperature is 4–5 °C / min;
[0026] The holding time after reaching the intermediate sintering temperature is 1.5 to 2.5 hours.
[0027] Preferably, the target sintering temperature in step (5) is 1200–1250 °C;
[0028] The heating rate from the intermediate sintering temperature to the target sintering temperature is 3-4 °C / min;
[0029] The holding time after reaching the target sintering temperature is 4.5 to 5.5 hours.
[0030] The beneficial effects of this invention are:
[0031] This invention provides an NTC material: Mn a Co b Ni c Fe d Al 1-a-b-c-d O4, wherein 0.50≤a≤0.55, 0.060≤b≤0.065, 0.20≤c≤0.25, and 0.025≤d≤0.030. The NTC material prepared according to this invention is used to prepare gold and silver electrode materials. Both electrode materials exhibit excellent electrical properties, with very small deviations from the RT values of the Japanese 1K / 4537 product. Furthermore, both electrode materials demonstrate excellent high-temperature stability; after aging at 300℃ for 1000 hours, the changes in R25 and B100 / 200 are minimal. The NTC material of this invention contains appropriate element types and proportions, has a simple preparation process, low cost, and good reproducibility, laying the foundation for the widespread application of NTC materials. Attached Figure Description
[0032] Figure 1 This is a RT diagram of the Shibaura 1K / 4537 product from Japan. Detailed Implementation
[0033] This invention provides an NTC material, wherein the NTC material is Mn a Co b Ni c Fe d Al 1-a-b-c-d O4; where 0.50≤a≤0.55, 0.060≤b≤0.065, 0.20≤c≤0.25, and 0.025≤d≤0.030.
[0034] In this invention, the range of a is 0.50≤a≤0.55, preferably 0.51≤a≤0.54, more preferably 0.515≤a≤0.535, and even more preferably 0.52≤a≤0.53.
[0035] In this invention, the range of b is 0.060≤b≤0.065, preferably 0.061≤b≤0.064, more preferably 0.0615≤b≤0.0635, and even more preferably 0.062≤b≤0.063.
[0036] In this invention, the range of c is 0.20≤c≤0.25, preferably 0.21≤c≤0.24, more preferably 0.215≤c≤0.235, and even more preferably 0.22≤c≤0.23.
[0037] In this invention, the range of d is 0.025≤d≤0.030, preferably 0.026≤d≤0.029, more preferably 0.0265≤d≤0.0285, and even more preferably 0.027≤d≤0.028.
[0038] The present invention also provides a method for preparing the NTC material, comprising the following steps:
[0039] (1) Manganese sulfate, cobalt sulfate, nickel sulfate, ferrous sulfate, aluminum sulfate and water are mixed to obtain a metal salt solution;
[0040] (2) The metal salt solution, oxalic acid solution and ammonia water were mixed and subjected to co-precipitation and aging in sequence to obtain the precursor;
[0041] (3) The precursor is calcined to obtain ceramic powder;
[0042] (4) The ceramic powder and polyvinyl alcohol solution are mixed and granulated to obtain granulated powder;
[0043] (5) The granulated powder is pressed and sintered in sequence to obtain the NTC material.
[0044] In this invention, the manganese sulfate in step (1) is preferably manganese sulfate monohydrate, the cobalt sulfate is preferably cobalt sulfate heptahydrate, the nickel sulfate is preferably nickel sulfate hexahydrate, the ferrous sulfate is preferably ferrous sulfate heptahydrate, and the aluminum sulfate is preferably aluminum sulfate octadecahydrate; the concentration of metal ions in the metal salt solution in step (1) is preferably 1-2 mol / L, more preferably 1.2-1.8 mol / L, and more preferably 1.5-1.6 mol / L.
[0045] In this invention, the concentration of the oxalic acid solution in step (2) is preferably 1 to 2 mol / L, more preferably 1.2 to 1.8 mol / L, and even more preferably 1.5 to 1.6 mol / L.
[0046] In this invention, the molar ratio of metal ions in the metal salt solution in step (1) to oxalic acid in the oxalic acid solution in step (2) is preferably 1:1.5 to 2, more preferably 1:1.6 to 1.9, and even more preferably 1:1.7 to 1.8.
[0047] In this invention, ammonia is added in step (2) to adjust the pH value during the coprecipitation reaction. The mass fraction of the ammonia in step (2) is preferably 25-28%, more preferably 25.5-27.5%, and even more preferably 26-27%.
[0048] In this invention, the pH value of the solution obtained by mixing in step (2) is preferably 3.5 to 4, more preferably 3.6 to 3.9, and even more preferably 3.7 to 3.8.
[0049] In this invention, the temperature of the coprecipitation reaction in step (2) is preferably 45-55°C, more preferably 47-53°C, and even more preferably 50-51°C; the time of the coprecipitation reaction is preferably 1-3 hours, more preferably 1.5-2.5 hours, and even more preferably 1.9-2 hours.
[0050] In this invention, the aging temperature in step (2) is preferably 20-30°C, more preferably 22-28°C, and even more preferably 25-26°C; the aging time is preferably 12-24h, more preferably 16-20h, and even more preferably 17-18h.
[0051] In this invention, after the aging process in step (2) is completed, the obtained solution is filtered, and then the obtained solid is washed with water, washed with anhydrous ethanol and dried in sequence to obtain the precursor.
[0052] In this invention, the number of water washes is preferably ≥2 times, more preferably ≥3 times, and even more preferably ≥4 times; the number of anhydrous ethanol washes is preferably ≥2 times, more preferably ≥3 times, and even more preferably ≥4 times; the drying temperature is preferably 75-80℃, more preferably 76-79℃, and even more preferably 77-78℃; the drying time is preferably 16-24h, more preferably 18-22h, and even more preferably 19-20h.
[0053] In this invention, the precursor obtained in step (2) is sequentially ball-milled and dried, and then calcined in step (3).
[0054] In this invention, the ball milling medium is preferably anhydrous ethanol; the ball milling speed is preferably 300–600 r / min, more preferably 350–550 r / min, and even more preferably 400–500 r / min; the ball milling time is preferably 3–6 h, more preferably 3.5–5.5 h, and even more preferably 4–5 h; the drying temperature is preferably 70–80 °C, more preferably 72–78 °C, and even more preferably 75–76 °C; and the drying time is preferably 10–14 h, more preferably 11–13 h, and even more preferably 11.5–12 h.
[0055] In this invention, the calcination temperature in step (3) is preferably 650-850°C, more preferably 700-800°C, and even more preferably 750-760°C; the calcination time is preferably 2-5 hours, more preferably 3-4 hours, and even more preferably 3.3-3.5 hours.
[0056] In this invention, after the calcination in step (3) is completed, the obtained sample is ball-milled and dried in sequence to obtain ceramic powder.
[0057] In this invention, the ball milling medium is preferably anhydrous ethanol; the ball milling speed is preferably 300–600 r / min, more preferably 350–550 r / min, and even more preferably 400–500 r / min; the ball milling time is preferably 3–6 h, more preferably 3.5–5.5 h, and even more preferably 4–5 h; the drying temperature is preferably 70–80 °C, more preferably 72–78 °C, and even more preferably 75–76 °C; and the drying time is preferably 10–14 h, more preferably 11–13 h, and even more preferably 11.5–12 h.
[0058] In this invention, the mass fraction of the polyvinyl alcohol solution in step (4) is preferably 3.5-4.5%, more preferably 3.7-4.3%, and even more preferably 4-4.1%.
[0059] In this invention, the mass ratio of ceramic powder to polyvinyl alcohol solution in step (4) is preferably 90-95:5-10, more preferably 91-94:6-9, and even more preferably 92-93:7-8.
[0060] In this invention, the pressing pressure in step (5) is preferably 8 to 300 MPa, more preferably 50 to 250 MPa, and even more preferably 100 to 200 MPa.
[0061] In this invention, the granulated powder is pressed into shape and then sintered; the intermediate temperature of sintering in step (5) is preferably 400-550°C, more preferably 450-500°C, and even more preferably 460-470°C.
[0062] In this invention, the heating rate from room temperature to the intermediate sintering temperature is preferably 4 to 5 °C / min, more preferably 4.2 to 4.7 °C / min, and even more preferably 4.5 to 4.6 °C / min.
[0063] In this invention, the holding time after reaching the intermediate sintering temperature is preferably 1.5 to 2.5 hours, more preferably 1.7 to 2.3 hours, and even more preferably 1.9 to 2 hours.
[0064] In this invention, the target temperature for sintering in step (5) is preferably 1200-1250°C, more preferably 1210-1240°C, and even more preferably 1220-1225°C.
[0065] In this invention, the heating rate from the intermediate sintering temperature to the target sintering temperature is preferably 3 to 4 °C / min, more preferably 3.2 to 3.8 °C / min, and even more preferably 3.5 to 3.6 °C / min.
[0066] In this invention, the holding time after reaching the target sintering temperature is preferably 4.5 to 5.5 hours, more preferably 4.7 to 5.3 hours, and even more preferably 5 to 5.1 hours.
[0067] In this invention, after sintering in step (5), the temperature is lowered to obtain the NTC material.
[0068] In this invention, the intermediate temperature for cooling is preferably 800-900°C, more preferably 820-880°C, and even more preferably 850-860°C; the cooling rate from the target sintering temperature to the intermediate temperature is preferably 1-2°C / min, more preferably 1.2-1.8°C / min, and even more preferably 1.5-1.6°C / min; after cooling to the intermediate temperature, the material is cooled to room temperature in the furnace to obtain the NTC material.
[0069] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0070] Example 1
[0071] In this embodiment, the NTC material is Mn. 0.53836 Co 0.06015 Ni 0.23104 Fe 0.02782 Al 0.14263 O4.
[0072] Manganese sulfate monohydrate, cobalt sulfate heptahydrate, nickel sulfate hexahydrate, ferrous sulfate heptahydrate, aluminum sulfate octadecahydrate, and water were mixed to obtain a metal salt solution (metal ion concentration of 1.5 mol / L). The metal salt solution, a 1.5 mol / L oxalic acid solution, and 26% ammonia solution were mixed (molar ratio of metal ions in the metal salt solution to oxalic acid in the oxalic acid solution was 1:1.7, and the pH of the resulting solution was 3.7). A co-precipitation reaction was carried out at 50°C for 2 hours, followed by aging at 25°C for 17 hours. The resulting solution was filtered, and the solid was washed three times with water, then three times with anhydrous ethanol, and finally dried at 80°C for 16 hours to obtain the precursor. The precursor was ball-milled at 400 r / min for 5 hours (ball-milling medium was anhydrous ethanol). After ball-milling, the solution was dried at 70°C. The sample was dried at ℃ for 14 hours, then calcined at 750℃ for 3.5 hours. The resulting sample was ball-milled at 400 r / min for 5 hours (the ball-milling medium was anhydrous ethanol), and finally dried at 70℃ for 14 hours to obtain ceramic powder. The ceramic powder was mixed with a 4% (w / w) polyvinyl alcohol solution (the preferred mass ratio of ceramic powder to polyvinyl alcohol solution was 92:8) and granulated to obtain granulated powder. The granulated powder was then pressed into shape under a pressure of 100 MPa and sintered. The sintering program was set as follows: first, the temperature was increased to 460℃ at a heating rate of 4.5℃ / min and held for 2 hours; then, the temperature was increased to 1220℃ at a heating rate of 3.5℃ / min and held for 5 hours; after sintering, the temperature was decreased to 850℃ at a cooling rate of 1.5℃ / min and finally cooled to room temperature in the furnace to obtain NTC material.
[0073] The NTC material obtained in this embodiment was prepared into a silver electrode material using conventional techniques in the art (the specific process is polishing → applying silver paste → sintering → cooling → soldering silver leads). The RT characteristics of the silver electrode material were tested, and the test results of the RT characteristics of the silver electrode material in this embodiment are shown in Table 1.
[0074] Table 1. RT characteristic test results of the silver electrode material in Example 1
[0075]
[0076]
[0077] The NTC material obtained in this embodiment was prepared into a gold electrode material using conventional techniques in the art (the specific process is polishing → applying gold paste → sintering → cooling → soldering gold leads). The RT characteristics of the gold electrode material were tested, and the test results of the RT characteristics of the gold electrode material in this embodiment are shown in Table 2.
[0078] Table 2. RT characteristic test results of the gold electrode material in Example 1.
[0079]
[0080]
[0081]
[0082] The RT (Release Time) table for the Shibaura 1K / 4537 product can be found at "https: / / www.shibaura-e.jp / products / download_catalog / ". Specifically, this invention provides the RT diagram for the Shibaura 1K / 4537 product, as follows: Figure 1 As shown (see details) Figure 1 (Data in column P□□-312 of the medium specification). Based on Table 1, Table 2, and... Figure 1 It can be seen that the RT characteristic test results of the silver electrode material and gold electrode material prepared using the NTC material in this embodiment have very small deviations from the RT performance of the Japanese 1K / 4537 product. That is, the NTC material prepared in this embodiment has excellent electrical properties and is comparable in quality to the Japanese 1K / 4537 product.
[0083] Silver electrode materials were prepared under the same conditions as described above, and this process was repeated 999 times to obtain 999 silver electrode materials. Thirty samples were then taken from these samples. The 30 silver electrode materials were then subjected to high-temperature stability tests (first testing the R value of the untreated sample). 25 (Resistance of the material at 25℃), R 100 (Resistance of the material at 100℃) and R 200 (Resistance of the material at 200℃), then aged at 300℃ for 250h, 500h, 750h, and 1000h respectively, and R was retested. 25 R 100 and R 200 The electrical performance test results of different silver electrode materials after aging at 300℃ for 250h are shown in Table 3 (B 100 / 200 The calculation formula is B 100 / 200 =(lnR) 100 -lnR 200 The electrical performance test results of different silver electrode materials after aging at 300℃ for 500h are shown in Table 4; the electrical performance test results of different silver electrode materials after aging at 300℃ for 750h are shown in Table 5; the electrical performance test results of different silver electrode materials after aging at 300℃ for 1000h are shown in Table 6.
[0084] Table 3. Electrical performance test results of different silver electrode materials after aging at 300℃ for 250 h.
[0085]
[0086]
[0087]
[0088] Table 4. Electrical performance test results of different silver electrode materials after aging at 300℃ for 500h.
[0089]
[0090]
[0091]
[0092] Table 5. Electrical performance test results of different silver electrode materials after aging at 300℃ for 750 h.
[0093]
[0094]
[0095] Table 6. Electrical performance test results of different silver electrode materials after aging at 300℃ for 1000h.
[0096]
[0097]
[0098]
[0099] Gold electrode materials were prepared according to the above conditions, and the process was repeated 999 times to obtain 999 gold electrode materials. Thirty gold electrode materials were then sampled. The 30 gold electrode materials were then subjected to high-temperature stability testing (first testing the R value of the untreated material). 25 (Resistance of the material at 25℃), R 100 (Resistance of the material at 100℃) and R 200 (Resistance of the material at 200℃), then aged at 300℃ for 250h, 500h, 750h, and 1000h respectively, and R was retested. 25 R 100 and R 200 The electrical performance test results of different gold electrode materials after aging at 300℃ for 250h are shown in Table 7 (B). 100 / 200 The calculation formula is B 100 / 200 =(lnR) 100 -lnR 200The electrical performance test results of different gold electrode materials after aging at 300℃ for 500h are shown in Table 8; the electrical performance test results of different gold electrode materials after aging at 300℃ for 750h are shown in Table 9; the electrical performance test results of different gold electrode materials after aging at 300℃ for 1000h are shown in Table 10.
[0100] Table 7. Electrical performance test results of different gold electrode materials after aging at 300℃ for 250 h.
[0101]
[0102]
[0103]
[0104]
[0105] Table 8. Electrical performance test results of different gold electrode materials after aging at 300℃ for 500h.
[0106]
[0107]
[0108]
[0109] Table 9. Electrical performance test results of different gold electrode materials after aging at 300℃ for 750 h.
[0110]
[0111]
[0112]
[0113]
[0114] Table 10 Electrical performance test results of different gold electrode materials after aging at 300℃ for 1000h.
[0115]
[0116]
[0117]
[0118] According to Tables 3-10, the NTC material prepared using the preparation conditions provided in this embodiment was used to prepare silver and gold electrode materials. After aging the silver and gold electrode materials at 300°C for 1000 hours, R...25 and B 100 / 200 The small rate of change indicates that the NTC material prepared according to the preparation conditions provided in this embodiment has excellent high-temperature stability; at the same time, the R value and B value of the 30 samples are not much different, proving that the preparation scheme of this embodiment has good reproducibility.
[0119] Example 2
[0120] In this embodiment, the NTC material is Mn. 0.51 Co 0.062 Ni 0.235 Fe 0.027 Al 0.166 O4.
[0121] Manganese sulfate monohydrate, cobalt sulfate heptahydrate, nickel sulfate hexahydrate, ferrous sulfate heptahydrate, aluminum sulfate octadecahydrate, and water were mixed to obtain a metal salt solution (metal ion concentration of 1.8 mol / L). The metal salt solution, a 2 mol / L oxalic acid solution, and 25% ammonia solution were mixed (molar ratio of metal ions in the metal salt solution to oxalic acid in the oxalic acid solution was 1:1.6, and the pH of the resulting solution was 3.9). A co-precipitation reaction was carried out at 53℃ for 1.5 h, followed by aging at 20℃ for 24 h. The resulting solution was filtered, and the solid was washed three times with water, then three times with anhydrous ethanol, and finally dried at 75℃ for 24 h to obtain the precursor. The precursor was ball-milled at 500 r / min for 4 h (ball milling medium was anhydrous ethanol). After ball milling, the solution was dried at 8... The sample was dried at 0℃ for 10 hours, then calcined at 800℃ for 3 hours. The resulting sample was ball-milled at 500 r / min for 4 hours (the ball-milling medium was anhydrous ethanol), and finally dried at 80℃ for 10 hours to obtain ceramic powder. The ceramic powder was mixed with a 3.7% polyvinyl alcohol solution (the preferred mass ratio of ceramic powder to polyvinyl alcohol solution was 93:7) and granulated to obtain granulated powder. The granulated powder was then pressed into shape under a pressure of 300 MPa and sintered. The sintering program was set as follows: first, the temperature was increased to 500℃ at a heating rate of 4℃ / min and held for 1.7 hours; then, the temperature was increased to 1250℃ at a heating rate of 3℃ / min and held for 4.5 hours; after sintering, the temperature was decreased to 860℃ at a cooling rate of 1℃ / min and finally cooled to room temperature in the furnace to obtain NTC material.
[0122] The NTC material obtained in this embodiment was prepared into silver electrode material using conventional techniques in the art. The silver electrode material was prepared under the same conditions as described above, repeated 499 times, resulting in 500 silver electrode materials. Ten silver electrode materials were then sampled. The 10 silver electrode materials were then subjected to high-temperature stability testing (first testing the R value of the untreated material). 25 (Resistance of the material at 25℃), R100 (Resistance of the material at 100℃) and R 200 (Resistance of the material at 200℃), then aged at 300℃ for 750 hours, and R was retested. 25 R 100 and R 200 The electrical performance test results of different silver electrode materials after aging at 300℃ for 750h are shown in Table 11.
[0123] Table 11 Electrical performance test results of different silver electrode materials after aging at 300℃ for 750 h
[0124]
[0125]
[0126] As shown in Table 11, the NTC material prepared using the preparation conditions provided in this embodiment was used to prepare a silver electrode material. After aging the silver electrode material at 300°C for 750 hours, R... 25 and B 100 / 200 The small rate of change indicates that the NTC material prepared according to the preparation conditions provided in this embodiment has excellent high-temperature stability; at the same time, the R value and B value of the 10 samples are not much different, proving that the preparation scheme of this embodiment has good reproducibility.
[0127] As can be seen from the above embodiments, the present invention provides an NTC material:
[0128] Mn a Co b Ni c Fe d Al 1-a-b-c-d O4, wherein 0.50≤a≤0.55, 0.060≤b≤0.065, 0.20≤c≤0.25, 0.025≤d≤0.030. The NTC material prepared according to this invention is used to prepare gold and silver electrode materials. Both electrode materials exhibit excellent electrical properties, with very small deviations from the RT values of the Japanese 1K / 4537 product. Furthermore, both electrode materials demonstrate excellent high-temperature stability; after aging at 300℃ for 1000 hours, the R... 25 and B 100 / 200 The rate of change is very small; the types and proportions of elements contained in the NTC material of this invention are appropriate, the preparation process is simple and low in cost, and it has good reproducibility, laying the foundation for the widespread application of NTC materials.
[0129] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. An application of an NTC material in the preparation of electrode materials, characterized in that, The NTC material is Mn. a Co b Ni c Fe d Al 1-a-b-c-d O4, 0.50≤a≤0.55, 0.060≤b≤0.065, 0.20≤c≤0.25, 0.025≤d≤0.030; the electrode material is gold electrode material or silver electrode material; The method for preparing the NTC material includes the following steps: (1) Manganese sulfate, cobalt sulfate, nickel sulfate, ferrous sulfate, aluminum sulfate and water are mixed to obtain a metal salt solution; (2) The metal salt solution, oxalic acid solution and ammonia water were mixed and subjected to co-precipitation and aging in sequence to obtain the precursor; (3) The precursor is calcined to obtain ceramic powder; (4) The ceramic powder and polyvinyl alcohol solution are mixed and granulated to obtain granulated powder; (5) The granulated powder is pressed and sintered in sequence to obtain the NTC material; The intermediate temperature for sintering in step (5) is 400–550°C; The heating rate from room temperature to the intermediate sintering temperature is 4–5 °C / min; The holding time after reaching the intermediate sintering temperature is 1.5 to 2.5 hours; The target sintering temperature in step (5) is 1200–1250 °C; The heating rate from the intermediate sintering temperature to the target sintering temperature is 3-4 °C / min; The holding time after reaching the target sintering temperature is 4.5 to 5.5 hours.
2. The application of the NTC material according to claim 1 in the preparation of electrode materials, characterized in that, The concentration of metal ions in the metal salt solution described in step (1) is 1–2 mol / L; The concentration of the oxalic acid solution in step (2) is 1-2 mol / L; The molar ratio of metal ions in the metal salt solution in step (1) to oxalic acid in the oxalic acid solution in step (2) is 1:1.5-2.
3. The application of the NTC material according to claim 2 in the preparation of electrode materials, characterized in that, The mass fraction of the ammonia water in step (2) is 25-28%; The pH of the solution obtained by mixing in step (2) is 3.5 to 4.
4. The application of the NTC material according to claim 3 in the preparation of electrode materials, characterized in that, The temperature of the coprecipitation reaction in step (2) is 45-55°C, and the time of the coprecipitation reaction is 1-3 hours. The aging temperature in step (2) is 20-30°C, and the aging time is 12-24 hours.
5. The application of the NTC material according to claim 4 in the preparation of electrode materials, characterized in that, The calcination temperature in step (3) is 650-850℃, and the calcination time is 2-5h.
6. The application of the NTC material according to claim 5 in the preparation of electrode materials, characterized in that, The mass fraction of the polyvinyl alcohol solution in step (4) is 3.5% to 4.5%. The mass ratio of ceramic powder to polyvinyl alcohol solution in step (4) is 90-95:5-10.
7. The application of the NTC material according to claim 6 in the preparation of electrode materials, characterized in that, The pressing pressure in step (5) is 8 to 300 MPa.