Cerium-doped ZnO varistor and soluble cerium salt doping preparation method thereof

Abstract

The invention discloses a cerium-doped ZnO varistor and a soluble cerium salt doping preparation method thereof, and belongs to the technical field of ZnO varistors. The preparation method comprises the following steps: (1) weighing a ZnO piezoresistor raw material, wherein the content of Ce (CH3COO) 3 in the raw material is 0.5-1.8 wt.%; (2) slurry preparation: mixing a Ce (CH3COO) 3 solution and ZnO slurry, stirring, drying, pre-calcining, and crushing; adding other resistor raw materials, Al (NO3) 39H2O, a dispersing agent, a binding agent and deionized water, and carrying out ball milling treatment to obtain total slurry; (3) preparing a green body; and (4) sintering to obtain the cerium-doped ZnO varistor. According to the invention, soluble cerium salt is used as a resistor raw material, and the high-performance cerium-doped zinc oxide varistor is prepared in a liquid phase-solid phase synergistic doping mode.

Description

Technical Field

[0001] This invention relates to the field of ZnO varistors, specifically to a cerium-doped ZnO varistor and a method for preparing it by soluble cerium salt doping. Background Technology

[0002] Zinc oxide (ZnO) varistors are semiconductor ceramic devices made primarily of ZnO with the addition of various metal oxides through sintering. Their core function is overvoltage protection using nonlinear current-voltage characteristics. When the applied voltage is below a threshold, the ZnO varistor exhibits a high-resistivity state, allowing only microampere-level leakage current to pass through. Once the voltage exceeds the critical value, its resistance drops sharply to the milliohm level, forming a low-resistivity path, thus limiting the overvoltage to a safe range. Simultaneously, it absorbs transient large currents (up to thousands of amperes), protecting downstream circuits or equipment from surge damage. This characteristic makes it widely used in power system overvoltage protection, electronic equipment surge suppression, and lightning protection. Especially in scenarios requiring rapid response and high energy absorption, ZnO varistors, with their excellent nonlinear coefficient, high voltage gradient, and long-term stability, have become the most mainstream varistor material.

[0003] Rare earth doping plays a crucial role in ZnO varistors, with its mechanism involving multi-dimensional regulation of the material's microstructure and electrical properties. At the microscopic level, rare earth oxides undergo solid solution reactions with the ZnO matrix, forming spinel phases or accumulating in grain boundary regions. This effectively suppresses excessive ZnO grain growth, reducing grain size to the submicron level while simultaneously promoting the sintering densification process. This structural regulation not only increases the number of grain boundaries but also enhances the double Schottky barrier height at the grain boundaries, laying the foundation for improved nonlinear electrical properties.

[0004] Cerium is an important rare-earth element used to dopant ZnO varistors. Appropriate doping can significantly improve the performance of ZnO varistors, making it a commonly used rare-earth doping element in ZnO varistors. Existing technologies use cerium oxide (CeO2) as a cerium source for rare-earth doping improvement, but this solid-state doping method reveals fundamental limitations: firstly, CeO2 has low solid-state diffusion efficiency, making it impossible to achieve uniform doping at the molecular level, thus limiting the grain boundary control effect; secondly, this process requires sintering at temperatures above 1180℃, which not only significantly increases energy consumption but also easily induces abnormal grain growth. Of particular concern is that cerium oxide doping can form Bi6Ce2O at grain boundaries. 12 Second-phase materials, such as grain boundary barriers, are prone to local enrichment during sintering, which leads to uneven distribution of grain boundary barriers and exacerbates the risk of electric field distortion. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide a cerium-doped ZnO varistor and a method for preparing it by soluble cerium salt doping. The method uses soluble cerium salt as the resistive raw material and prepares a high-performance cerium-doped zinc oxide varistor by liquid-phase-solid phase synergistic doping.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a soluble cerium salt doped ZnO varistor, the method comprising the following steps: (1) Weighing raw materials: Weigh each raw material according to the raw material composition of the ZnO varistor; the raw material of the ZnO varistor is composed of ZnO, Bi2O3, Sb2O3, NiO, Mn3O4, Co3O4, Cr2O3 and Ce(CH3COO)3, and the proportion of Ce(CH3COO)3 in the raw material is 0.5-1.8 wt.%; (2) Slurry preparation: ZnO raw material is mixed with deionized water to obtain ZnO slurry. Ce(CH3COO)3 solution is mixed with ZnO slurry in proportion and stirred. After drying and pre-calcination, it is pulverized. Bi2O3, Sb2O3, NiO, Mn3O4, Co3O4 and Cr2O3 raw materials are added to the pulverized material. Al(NO3)3•9H2O, dispersant, binder and deionized water are added. The mixture is ball-milled and then passed through a 100-mesh sieve to obtain total slurry for later use. (3) Preparation of green body: The total slurry obtained in step (2) is spray granulated and aged in sequence, and then pressed into green body; (4) Sintering: After the blank obtained in step (3) is debinded, it is calcined at high temperature. The sample obtained after calcination is then post-processed to obtain the cerium-doped ZnO varistor.

[0007] Further, in step (1), the raw material composition of the ZnO varistor, by weight percentage, is as follows: ZnO 83-93 wt.%, Bi2O3 1.6-6 wt.%, Sb2O3 1-4 wt.%, NiO 1-3 wt.%, Mn3O4 0.5-3 wt.%, Co3O4 0.5-3 wt.%, Cr2O3 0.5-3 wt.%, and Ce(CH3COO)3 0.5-1.8 wt.%.

[0008] Further, in step (2), the weight ratio of ZnO to deionized water in the ZnO slurry is 1:(0.5-3); the stirring is mechanically stirred at a speed of 300-500 rpm for 0.5-2 hours; the drying temperature is 80-150℃; the pre-calcination treatment temperature is 800-1000℃, the holding time is 2-5 hours, and after cooling in the furnace, it is re-pulverized into powder.

[0009] Further, in step (2), the dispersant is polyvinyl alcohol (PVA), polyacrylamide, or sodium carboxymethyl cellulose, and the amount of dispersant added is 0.3-1.5% of the weight of solid powder in the total slurry; the binder is polyvinyl alcohol, and the amount of binder added is 0.3-1.5% of the weight of solid powder in the total slurry; the amount of Al(NO3)3•9H2O added is 0.01-0.03% of the weight of solid powder in the total slurry.

[0010] Further, in step (3), the spray granulation process is as follows: the total slurry is spray granulated using a spray dryer with an inlet temperature of 180-220℃ and an atomizing disc speed of 10000-15000 rpm.

[0011] Further, in step (3), the aging process is as follows: the granulated material obtained by spray granulation is mixed with deionized water and the release agent stearic acid, and the resulting mixture is left to stand at room temperature and under sealed conditions for 24-48 hours; the moisture content of the mixture is 1.0-1.5 wt.%, and the stearic acid content is 0.5-1.5 wt.%. Further, in step (3), the pressing molding is to press the aged granulated material into a blank using a hydraulic press, and adjust the pressure to control the density of the cylindrical blank to 3.1-3.4 g / cm³, and the blank diameter to 35-150 mm.

[0012] Further, in step (4), the degumming process is as follows: the blank obtained in step (3) is placed in a ventilated electric furnace for degumming, the temperature is controlled at 380-550℃, the organic matter in the blank is burned off, and the degumming process is completed.

[0013] Furthermore, in step (4), the high-temperature calcination temperature is 1000-1300℃, and the holding time is 1-4 hours.

[0014] Further, in step (4), the post-processing refers to the calcined sample being double-sided milled, ultrasonically cleaned, and dried, and then a metal electrode is prepared on the surface of the resulting resistor blank to obtain the finished ZnO varistor.

[0015] A cerium-doped ZnO varistor was prepared using the above method, with a varistor voltage gradient ≥350V / mm and an energy absorption density ≥250J / cm³.

[0016] The design mechanism and beneficial effects of this invention are as follows: 1. This invention is the first to use cerium acetate (Ce(CH3COO)3) instead of traditional cerium oxide powder as the cerium source. By mixing cerium acetate solution with ZnO powder slurry, atomic-level contact between cerium and ZnO is achieved. During the preparation of the total slurry, the decomposition and oxidation of cerium acetate are controlled through a pre-calcination process. During pre-calcination in an air environment, cerium acetate decomposes and oxidizes (cerium acetate decomposition conditions: 400-600℃, air atmosphere, heat preservation for 2 hours), and the reaction equation 4Ce(CH3COO)3 + O2 → 4CeO2 + 6CO2 + 6H2O occurs. After the reaction, cerium acetate surrounding the ZnO particles is converted into CeO2 in situ. Therefore, pre-calcination generates CeO2 that is uniformly adsorbed on the surface of the ZnO powder matrix, forming a CeO2-ZnO composite phase powder, which significantly increases the dispersion uniformity and doping efficiency of cerium.

[0017] 2. This invention uses cerium acetate as the dopant phase in the ZnO varistor, with cerium acetate (Ce(CH3COO)3) as an organometallic salt, uniformly dispersed in the ZnO matrix through solution mixing. This doping method avoids the problem of cerium oxide particle agglomeration in traditional solid-state methods, ensuring the uniform distribution of dopant elements at the microscale, thereby improving the consistency of the material's electrical properties.

[0018] 3. In the process of preparing ZnO varistors using cerium acetate as the cerium source in this invention, CeO2 generated from the decomposition and oxidation of cerium acetate segregates at the grain boundaries. 4+ Ions form acceptor defect traps, effectively modulating the grain boundary state density. This defect structure improves carrier transport properties, reducing leakage current. By refining the grains and strengthening the grain boundary barrier, the potential gradient of the prepared ZnO varistor was increased from 220 V / mm using conventional methods to 348 V / mm, while the energy absorption density reached 284 J / cm². 3 It improves upon traditional formulas by approximately 30%.

[0019] 4. In the ZnO varistor preparation process of this invention, the decomposition products of cerium acetate are cerium oxide (CeO2), CO2, and H2O, with no toxic gases generated, which aligns with the trend of green manufacturing. In contrast, the ball milling process of cerium oxide in the traditional solid-state method may generate dust pollution. Detailed Implementation

[0020] To further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments.

[0021] In the following embodiments, in step (c) of step 2, the dispersant is polyacrylamide, and the amount of dispersant added is 0.8% of the weight of solid powder in the total slurry; the binder is polyvinyl alcohol, and the amount of binder added is 0.8% of the weight of solid powder in the total slurry; the amount of Al(NO3)3•9H2O added is 0.02% of the weight of solid powder in the total slurry. Example 1:

[0022] This embodiment describes a method for preparing soluble cerium salt doping of cerium-doped ZnO varistors, and the specific process is as follows: 1. Preparation of raw materials for preparing resistor sheets: Weigh each raw material according to the raw material composition of the ZnO varistor; the raw material composition of the ZnO varistor is (wt.%): ZnO 91.75wt.%, Bi2O3 2.0wt.%, Sb2O3 2.0wt.%, NiO 1.0wt.%, Mn3O4 0.5wt.%, Co3O4 1.75wt.%, Cr2O3 0.5wt.%, Ce(CH3COO)3 0.5wt.

[0023] 2. Slurry preparation: (a) ZnO and deionized water are mixed evenly at a weight ratio of 1:1 to obtain ZnO slurry; (b) Ce(CH3COO)3 is mixed with deionized water to obtain a Ce(CH3COO)3 solution with a concentration of 5 g / L. The obtained Ce(CH3COO)3 solution is mixed with ZnO slurry in a certain proportion and stirred. After drying and pre-calcination, it is pulverized. The Ce(CH3COO)3 solution has a weight ratio of Ce(CH3COO)3 to ZnO in the ZnO slurry of 0.5:91.75. The stirring speed is 350 rpm and the stirring time is 1.5 h. The drying temperature is 100 °C. The pre-calcination temperature is 900 °C and the holding time is 2.5 h. After cooling in the furnace, it is pulverized into powder again.

[0024] (c) Add raw materials Bi2O3, Sb2O3, NiO, Co3O4, Mn3O4 and Cr2O3 to the material obtained after crushing in proportion, then add Al(NO3)3•9H2O, dispersant, binder and deionized water, add to ball mill for ball milling treatment and pass through 100 mesh sieve to obtain total slurry for later use.

[0025] 3. Green body preparation: The total slurry obtained in step 2 is subjected to spray granulation and aging treatment in sequence, and then pressed into green bodies; the process is as follows: (a) Spray granulation: The prepared total slurry is spray granulated using a spray dryer; the inlet temperature is 200℃ and the atomizing disc speed is 10000rpm.

[0026] (b) Aging: The granulated material obtained by spray granulation is mixed with deionized water and release agent stearic acid, and the resulting mixture is left to stand for 36 hours at room temperature and under sealed conditions; the moisture content of the mixture is 1.1 wt.% and the stearic acid content is 1.0 wt.%.

[0027] (c) Molding: The aged granules are pressed into blanks using a hydraulic press. The pressure is adjusted to control the density of the cylindrical blanks at 3.25 g / cm³ and the blank diameter is 48 mm.

[0028] 4. Sintering: The blank obtained in step 3 is subjected to a debinding process. The process is as follows: the blank is placed in a ventilated electric furnace and heated to 450℃ to ablate the organic matter in the blank, thus completing the debinding process. After the debinding process, it is calcined at 1100℃ for 2 hours. After calcination, the resulting sample is double-sided ground, ultrasonically cleaned, and dried. Then, a metal electrode is prepared on the surface of the treated resistor blank to obtain the finished cerium-doped ZnO varistor.

[0029] The performance test results of the ZnO varistor obtained in this embodiment are as follows: The ZnO varistor produced in this embodiment has a diameter of 40 mm, a varistor voltage gradient of 353 V / mm, a nonlinear coefficient of 55, and can withstand 440 J / cm². 3 A 2ms square wave current pulse was applied 16 times. Example 2:

[0030] This embodiment describes a method for preparing soluble cerium salt doping of cerium-doped ZnO varistors, and the specific process is as follows: 1. Preparation of raw materials for preparing resistor sheets: Weigh each raw material according to the raw material composition of the ZnO varistor; the raw material composition of the ZnO varistor is (wt.%): ZnO 91.05wt.%, Bi2O3 2.0wt.%, Sb2O3 2.0wt.%, NiO 1.0wt.%, Mn3O4 0.5wt.%, Co3O4 1.75wt.%, Cr2O3 0.5wt.%, Ce(CH3COO)3 1.2wt.%.

[0031] 2. Slurry preparation: (a) ZnO and deionized water are mixed evenly at a weight ratio of 1:1 to obtain ZnO slurry; (b) Ce(CH3COO)3 is mixed with deionized water to obtain a Ce(CH3COO)3 solution with a concentration of 5 g / L. The obtained Ce(CH3COO)3 solution is mixed with ZnO slurry in a certain proportion and stirred. After drying and pre-calcination, it is pulverized. The weight ratio of Ce(CH3COO)3 to ZnO in the ZnO slurry is 1.2:91.05. The stirring speed is 400 rpm and the stirring time is 1 h. The drying temperature is 120℃. The pre-calcination temperature is 800℃ and the holding time is 3 hours. After cooling in the furnace, it is pulverized into powder again.

[0032] (c) Add raw materials Bi2O3, Sb2O3, NiO, Co3O4, Mn3O4 and Cr2O3 to the material obtained after crushing in proportion, then add Al(NO3)3•9H2O, dispersant, binder and deionized water, add to ball mill for ball milling treatment and pass through 100 mesh sieve to obtain total slurry for later use.

[0033] 3. Green body preparation: The total slurry obtained in step 2 is subjected to spray granulation and aging treatment in sequence, and then pressed into green bodies; the process is as follows: (a) Spray granulation: The prepared total slurry is spray granulated using a spray dryer; the inlet temperature is 200℃ and the atomizing disc speed is 12000rpm.

[0034] (b) Aging: The granulated material obtained by spray granulation is mixed with deionized water and release agent stearic acid, and the resulting mixture is left to stand for 24 hours at room temperature and under sealed conditions; the moisture content of the mixture is 1.2 wt.% and the stearic acid content is 1.0 wt.%.

[0035] (c) Molding: The aged granules are pressed into blanks using a hydraulic press. The pressure is adjusted to control the density of the cylindrical blanks at 3.25 g / cm³ and the blank diameter is 125 mm.

[0036] 4. Sintering: The blank obtained in step 3 is subjected to a debinding process. The process is as follows: the blank is placed in a ventilated electric furnace and heated to 450℃ to ablate the organic matter in the blank, thus completing the debinding process. After the debinding process, it is calcined at 1100℃ for 2 hours. After calcination, the resulting sample is double-sided ground, ultrasonically cleaned, and dried. Then, a metal electrode is prepared on the surface of the treated resistor blank to obtain the finished cerium-doped ZnO varistor.

[0037] The performance test results of the ZnO varistor obtained in this embodiment are as follows: The ZnO varistor produced in this embodiment has a diameter of 105 mm, a varistor voltage gradient of 383 V / mm, a nonlinear coefficient of 46, and can withstand 420 J / cm². 3A 2ms square wave current pulse was applied 16 times.

[0038] Example 3:

[0039] This embodiment describes a method for preparing soluble cerium salt doping of cerium-doped ZnO varistors, and the specific process is as follows: 1. Preparation of raw materials for preparing resistor sheets: Weigh each raw material according to the raw material composition of the ZnO varistor; the raw material composition of the ZnO varistor is (wt.%): ZnO 90.65wt.%, Bi2O3 2.0wt.%, Sb2O3 2.0wt.%, NiO 1.0wt.%, Mn3O4 0.5wt.%, Co3O4 1.75wt.%, Cr2O3 0.5wt.%, Ce(CH3COO)3 1.6wt.%.

[0040] 2. Slurry preparation: (a) ZnO and deionized water are mixed evenly at a weight ratio of 1:1 to obtain ZnO slurry; (b) Ce(CH3COO)3 is mixed with deionized water to obtain a Ce(CH3COO)3 solution with a concentration of 5 g / L. The obtained Ce(CH3COO)3 solution is mixed with ZnO slurry in a certain proportion and stirred. After drying and pre-calcination, it is pulverized. The weight ratio of Ce(CH3COO)3 in the Ce(CH3COO)3 solution to ZnO in the ZnO slurry is 1.6:90.65. The stirring speed is 400 rpm and the stirring time is 1 h. The drying temperature is 120℃. The pre-calcination temperature is 800℃ and the holding time is 2.5 h. After cooling in the furnace, it is pulverized into powder again.

[0041] (c) Add raw materials Bi2O3, Sb2O3, NiO, Co3O4, Mn3O4 and Cr2O3 to the material obtained after crushing in proportion, then add Al(NO3)3•9H2O, dispersant, binder and deionized water, add to ball mill for ball milling treatment and pass through 100 mesh sieve to obtain total slurry for later use.

[0042] 3. Green body preparation: The total slurry obtained in step 2 is subjected to spray granulation and aging treatment in sequence, and then pressed into green bodies; the process is as follows: (a) Spray granulation: The prepared total slurry is spray granulated using a spray dryer; the inlet temperature is 220℃ and the atomizing disc speed is 15000rpm.

[0043] (b) Aging: The granulated material obtained by spray granulation is mixed with deionized water and release agent stearic acid, and the resulting mixture is left to stand for 36 hours at room temperature and under sealed conditions; the moisture content of the mixture is 1.5 wt.% and the stearic acid content is 0.9 wt.%.

[0044] (c) Molding: The aged granulated material is pressed into a green body using a hydraulic press. The pressure is adjusted to control the density of the cylindrical green body at 3.25 g / cm³ and the diameter of the green body is 55 mm.

[0045] 4. Sintering: The blank obtained in step 3 is subjected to a debinding process. The process is as follows: the blank is placed in a ventilated electric furnace and heated to 450℃ to ablate the organic matter in the blank, thus completing the debinding process. After the debinding process, it is calcined at 1100℃ for 2 hours. After calcination, the resulting sample is double-sided ground, ultrasonically cleaned, and dried. Then, a metal electrode is prepared on the surface of the treated resistor blank to obtain the finished cerium-doped ZnO varistor.

[0046] The performance test results of the ZnO varistor obtained in this embodiment are as follows: The ZnO varistor produced in this embodiment has a diameter of 46 mm, a varistor voltage gradient of 406 V / mm, a nonlinear coefficient of 35, and can withstand 420 J / cm². 3 A 2ms square wave current pulse was applied 16 times.

[0047] Comparative Example 1: The difference between this example and Example 1 is that Comparative Example 1 does not use Ce(CH3COO)3, and the missing Ce(CH3COO)3 mass is supplemented by ZnO. The other processes are the same as in Example 1.

[0048] Experimental test analysis: In comparison, the varistor of undoped Ce(CH3COO)3 in Comparative Example 1 has a varistor potential gradient of 327 V / mm, a nonlinear coefficient of 59, and can withstand 350 J / cm². 3 A 2ms square wave current pulse was applied 16 times; the pulse could not pass through 400J / cm. 3 2ms square wave current impulse test.

[0049] Comparative Example 2: The difference between this example and Example 1 is that Comparative Example 2 uses the same amount of Ce(CH3COO)3 as Example 1, but does not employ the pre-doping step of Ce element on ZnO powder. That is, in the slurry preparation process, each resistor raw material is directly mixed with Al(NO3)3•9H2O, dispersant, binder and deionized water to prepare the total slurry. Other processes are the same as in Example 1.

[0050] Experimental test analysis: In contrast, the varistor in Comparative Example 2 has a varistor potential gradient of 235V / mm and a nonlinear coefficient of 11, and cannot pass through 16 cycles of 200J / cm. 3 2ms square wave current impulse test.

[0051] The foregoing has shown and described the main features and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a soluble cerium salt doped ZnO varistor, characterized in that: The method includes the following steps: (1) Weighing raw materials: Weigh each raw material according to the raw material composition of the ZnO varistor; the raw material of the ZnO varistor is composed of ZnO, Bi2O3, Sb2O3, NiO, Mn3O4, Co3O4, Cr2O3 and Ce(CH3COO)3, and the proportion of Ce(CH3COO)3 in the raw material is 0.5-1.8 wt.%; (2) Slurry preparation: ZnO raw material is mixed with deionized water to obtain ZnO slurry. Ce(CH3COO)3 solution is mixed with ZnO slurry in proportion and stirred. After drying and pre-calcination, it is pulverized. Bi2O3, Sb2O3, NiO, Mn3O4, Co3O4 and Cr2O3 raw materials are added to the pulverized material. Al(NO3)3•9H2O, dispersant, binder and deionized water are added. The mixture is ball-milled and then passed through a 100-mesh sieve to obtain total slurry for later use. (3) Preparation of green body: The total slurry obtained in step (2) is spray granulated and aged in sequence, and then pressed into green body; (4) Sintering: After the blank obtained in step (3) is debinded, it is calcined at high temperature. The sample obtained after calcination is then post-processed to obtain the cerium-doped ZnO varistor.

2. The method for preparing soluble cerium salt doping of the cerium-doped ZnO varistor according to claim 1, characterized in that: In step (1), the raw material composition of the ZnO varistor, by weight percentage, is as follows: ZnO 83-93 wt.%, Bi2O3 1.6-6 wt.%, Sb2O3 1-4 wt.%, NiO 1-3 wt.%, Mn3O4 0.5-3 wt.%, Co3O4 0.5-3 wt.%, Cr2O3 0.5-3 wt.%, and Ce(CH3COO)3 0.5-1.8 wt.%.

3. The method for preparing soluble cerium salt doping of the cerium-doped ZnO varistor according to claim 1, characterized in that: In step (2), the weight ratio of ZnO to deionized water in the ZnO slurry is 1:(0.5-3); the stirring is mechanically stirred at a speed of 300-500 rpm for 0.5-2 hours; the drying temperature is 80-150℃; the pre-calcination treatment temperature is 800-1000℃, the holding time is 2-5 hours, and after cooling in the furnace, it is re-pulverized into powder.

4. The method for preparing soluble cerium salt doping of the cerium-doped ZnO varistor according to claim 1, characterized in that: In step (2), the dispersant is polyvinyl alcohol (PVA), polyacrylamide, or sodium carboxymethyl cellulose, and the amount of dispersant added is 0.3-1.5% of the weight of solid powder in the total slurry; the binder is polyvinyl alcohol, and the amount of binder added is 0.3-1.5% of the weight of solid powder in the total slurry; the amount of Al(NO3)3•9H2O added is 0.01-0.03% of the weight of solid powder in the total slurry.

5. The method for preparing a soluble cerium salt-doped varistor according to claim 1, characterized in that: In step (3), the spray granulation process is as follows: the total slurry is spray granulated using a spray dryer with an inlet temperature of 180-220℃ and an atomizing disc speed of 10000-15000 rpm.

6. The method for preparing soluble cerium salt doping of the cerium-doped ZnO varistor according to claim 1, characterized in that: In step (3), the aging process is as follows: after mixing the granulated material obtained by spray granulation with deionized water and release agent stearic acid, the resulting mixture is left to stand for 24-48 hours at room temperature and under sealed conditions; the moisture content of the mixture is 1.0-1.5 wt.% and the stearic acid content is 0.5-1.5 wt.%.

7. The method for preparing soluble cerium salt doping of the cerium-doped ZnO varistor according to claim 1, characterized in that: In step (3), the pressing molding is to press the aged granulated material into a blank using a hydraulic press, and adjust the pressure to control the density of the cylindrical blank to 3.1-3.4 g / cm³, and the blank diameter to 35-150 mm.

8. The method for preparing soluble cerium salt doping of the cerium-doped ZnO varistor according to claim 1, characterized in that: In step (4), the degumming process is as follows: the blank obtained in step (3) is placed in a ventilated electric furnace for degumming, the temperature is controlled at 380-550℃, the organic matter in the blank is burned off, and the degumming process is completed.

9. The method for preparing a soluble cerium salt-doped varistor according to claim 1, characterized in that: In step (4), the high-temperature calcination temperature is 1000-1300℃, and the holding time is 1-4 hours.

10. A cerium-doped ZnO varistor prepared by the method according to any one of claims 1-9, characterized in that: The ZnO varistor has a varistor voltage gradient ≥350V / mm and an energy absorption density ≥250J / cm³.