Boron nitride fiber inert choke ring for thermal battery and preparation method of boron nitride fiber inert choke ring

Abstract

The invention discloses a boron nitride fiber inert choke ring for a thermal battery and a preparation method thereof, the boron nitride fiber inert choke ring for the thermal battery comprises a plurality of annular boron nitride fiber paper; the annular boron nitride fiber paper comprises boron nitride fibers arranged in a net shape and magnesium oxide particles A attached to the surfaces of the boron nitride fibers. Pores of the boron nitride fibers are filled with magnesium oxide particles B. The boron nitride fiber inert choke ring for the thermal battery can be industrially produced, and is high in production efficiency, resistant to high temperature, resistant to corrosion, good in heat insulation performance and harmless to human bodies and the environment.

Description

Technical Field

[0001] The present invention relates to the field of thermal battery choke rings, and more particularly to the field of boron nitride fiber inert choke rings for thermal batteries and their preparation methods. Background Art

[0002] Thermal batteries are widely used in various weapons, especially playing a huge role in large and medium-caliber shells, scatter bombs, etc.; thermal batteries are primary reserve batteries that use molten salt as an electrolyte and are activated by their own heat sources, having the advantages of short activation time, large output power, high specific energy, wide operating temperature range, long storage time, etc. The core component of a thermal battery is a composite sheet, which usually consists of a positive electrode, an insulating sheet, a negative electrode, and a choke ring.

[0003] On the one hand, the choke ring prevents the heating sheet from reacting with the negative electrode (materials such as highly active lithium-silicon alloy or lithium-boron alloy) or being ablated during combustion, playing a role in protecting the stack; on the other hand, it prevents the electrolyte molten salt from overflowing under the action of high environmental forces during the operation of the thermal battery, causing a short circuit. Therefore, the choke ring needs to have heat resistance, chemical corrosion resistance, and good electrical insulation; the traditional choke ring is made of asbestos material, but the asbestos material has reactivity with molten lithium, and the prior art cannot solve the problem of the harmfulness of asbestos dust.

[0004] How to efficiently and high-quality prepare an inert choke ring for a thermal battery with high temperature resistance, corrosion resistance, good heat insulation performance, and environmental friendliness has become an urgent problem to be solved in this field. Summary of the Invention

[0005] The purpose of the present invention is to provide a boron nitride fiber inert choke ring for a thermal battery and its preparation method, realizing the industrial production of the boron nitride fiber inert choke ring for a thermal battery, with high production efficiency, high temperature resistance, corrosion resistance, good heat insulation performance, and being harmless to the human body and the environment.

[0006] According to one aspect of the present invention, a boron nitride fiber inert choke ring for a thermal battery is provided, which includes a plurality of annular boron nitride fiber papers;

[0007] The plurality of annular boron nitride fiber papers include boron nitride fibers arranged in a network and magnesium oxide particles A attached to the surface of the boron nitride fibers;

[0008] The pores of the boron nitride fibers are filled with magnesium oxide particles B.

[0009] The beneficial effects of the present invention compared with the prior art are as follows. The inert flow-blocking ring made of boron nitride fibers for thermal batteries includes several annular boron nitride fiber papers. That is, by using boron nitride, the finished flow-blocking ring has high heat resistance, chemical corrosion resistance, and good electrical insulation. At the same time, boron nitride exists in the form of fiber papers, which has high strength, toughness, and porosity, thus achieving good heat insulation performance.

[0010] Through the magnesium oxide particles A on the surface of the boron nitride fibers, the uniform combination of magnesium oxide and boron nitride fibers is realized. Thus, even if a small amount of electrolyte liquid leaks and enters the pores of the boron nitride fibers, it will react with the magnesium oxide particles A on the surface of the boron nitride fibers, blocking the electrolyte within the flow-blocking ring and preventing the electrolyte from contacting the electrodes.

[0011] The pores of the boron nitride fibers are filled with magnesium oxide particles B, which further facilitates the reaction between the electrolyte entering the pores of the boron nitride fibers and the magnesium oxide particles, further blocking the electrolyte within the flow-blocking ring and preventing the electrolyte from contacting the electrodes.

[0012] Furthermore, the outer diameter of the inert flow-blocking ring made of boron nitride fibers for thermal batteries is 23 - 100 mm, the inner diameter is 20 - 97, and the height is 1.4 - 7 mm.

[0013] The beneficial effect of the above step is that it is possible to prepare a large-sized inert flow-blocking ring made of boron nitride fibers for thermal batteries, and the flow-blocking ring includes several annular boron nitride fiber papers.

[0014] Furthermore, the porosity of the inert flow-blocking ring made of boron nitride fibers for thermal batteries is 60 - 90%;

[0015] The porosity of the magnesium oxide particles B is 40 - 60%;

[0016] The particle size of the magnesium oxide particles A is 0.01 μm - 2 μm; the particle size of the magnesium oxide particles B is 5 μm - 5 μm;

[0017] and / or

[0018] The intersection points of the boron nitride fibers are coated with boron nitride.

[0019] The beneficial effect of the above step is that when the porosity of the inert flow-blocking ring made of boron nitride fibers for thermal batteries is 60 - 90%, it not only realizes good heat insulation performance but also, when electrolyte overflows, avoids phenomena such as an increase in the internal pressure of the battery and battery bulging caused by the overly dense flow-blocking ring, thus improving the battery life; the overflowing electrolyte solution enters the pores of the flow-blocking ring and reacts with magnesium oxide in the flow-blocking ring to solidify, thereby preventing it from contacting the electrodes.

[0020] With the particle size of the magnesium oxide particle B being 5 μm - 5 μm, it is beneficial for the boron nitride fiber and the magnesium oxide particle B to react and mix during the preparation process to produce a boron nitride fiber paper blank, enabling the fibers and particles to be evenly dispersed and preventing particle agglomeration;

[0021] With the porosity of the magnesium oxide particle B being 40 - 60%, the specific surface area of the magnesium oxide particle B in contact with the electrolyte is significantly increased, thereby significantly improving the efficiency and amount of electrolyte curing; thus improving the efficiency of isolating the electrolyte by the boron nitride fiber inert flow blocking ring for thermal batteries;

[0022] With the particle size of the magnesium oxide particle A being 0.01 μm - 2 μm, its small particle size and large specific surface area are beneficial for improving the curing efficiency of the magnesium oxide particle A and the electrolyte, and improving the efficiency of isolating the electrolyte by the boron nitride fiber inert flow blocking ring for thermal batteries; the small particle size of the magnesium oxide particle A has problems such as easy agglomeration, uneven dispersion, and clogging of the pores between boron nitride fibers, reducing the porosity. However, by first attaching the magnesium oxide particle A to the surface of the boron nitride fiber and then using the boron nitride fiber with attached magnesium oxide particle A to produce a boron nitride fiber paper blank, the problems caused by the easy agglomeration of the magnesium oxide particle A due to its small particle size are avoided;

[0023] By coating boron nitride at the intersection points of the boron nitride fibers, the bonding strength between the boron nitride fibers is high, increasing the strength of the finished flow blocking ring and preventing changes in its internal structure; at the same time, it avoids the reduction and uncontrollability of the porosity due to the filling of boron nitride in the pores where the boron nitride fibers intersect.

[0024] According to another aspect of the present invention, there is provided a method for preparing a boron nitride fiber inert flow blocking ring for thermal batteries, characterized by comprising the following steps:

[0025] Prepare short-cut boron nitride fibers;

[0026] Prepare a fiber modification solution, the fiber modification solution comprising magnesium oxide particle A and boron oxide;

[0027] Modify the short-cut boron nitride fibers with the fiber modification solution to obtain modified boron nitride fibers;

[0028] Prepare a boron nitride fiber paper slurry;

[0029] Perform papermaking, filtration, and drying on the boron nitride fiber paper slurry to form a boron nitride fiber paper blank;

[0030] Then heat-treat the boron nitride fiber paper blank to obtain a boron nitride fiber paper;

[0031] Stamp several layers of boron nitride fiber paper to obtain an inert flow-blocking ring made of boron nitride fiber for thermal batteries; preferably, when the boron nitride fiber paper slurry is made into paper, filtered, and dried, the drying temperature is 80-120 °C; the boron nitride fiber paper blank can be a large fiber paper blank, and the length and width dimensions can reach 600-200*600-200 mm;

[0032] Preferably, the heat treatment process of the boron nitride fiber paper blank is to rise from room temperature to 500-600 °C, the heating rate is 3-5 °C / min, and the heat treatment atmosphere is air.

[0033] The beneficial effect of the present invention compared with the prior art is that the fiber modification solution includes magnesium oxide particles A and boron oxide, and the fiber modification solution modifies the short-cut boron nitride fibers; magnesium oxide particles A and boron oxide are obtained on the surface of the obtained modified boron nitride fibers; thus, the boron nitride fibers and magnesium oxide particles A in the finished product flow-blocking ring are evenly combined, and the problem that when the particle size of magnesium oxide particles A is small, it is easy to agglomerate and disperse unevenly and block the pores between boron nitride fibers, reducing the porosity, is also avoided;

[0034] By making the boron nitride fiber paper slurry into paper, suction filtration, and drying to form a boron nitride fiber paper blank, and then heat-treating the boron nitride fiber paper blank to obtain boron nitride fiber paper; an inert flow-blocking ring made of boron nitride fiber for thermal batteries is obtained, which includes several annular boron nitride fiber papers, and the annular boron nitride fiber papers include boron nitride fibers arranged in a network and magnesium oxide particles A attached to the surface of the boron nitride fibers; thus, the finished product flow-blocking ring has high heat resistance, chemical corrosion resistance, and good electrical insulation, and because boron nitride exists in the structure of the fiber paper, it has high strength and toughness while having a high porosity, thus achieving good heat insulation performance.

[0035] Furthermore, the length of the short-cut boron nitride fibers is 0.2 mm-20 mm; the particle size of the magnesium oxide particles A is 0.01 μm-2 μm; the mass ratio of the short-cut boron nitride fibers to the magnesium oxide particles A is 1:(0.8-1.2).

[0036] The beneficial effect of the previous step is that the porosity of the inert flow-blocking ring made of boron nitride fiber for thermal batteries is 60-90%, thus achieving good heat insulation performance. At the same time, when electrolyte overflows occur, the phenomenon that the internal pressure of the battery increases due to the overly dense flow-blocking ring, resulting in battery bulging and other phenomena, is avoided, thereby improving the battery service life; the overflowing electrolyte solution enters the pores of the flow-blocking ring and reacts with magnesium oxide in the flow-blocking ring to solidify, thereby preventing it from contacting the electrode;

[0037] The particle size of the magnesium oxide particle A is 0.01 μm - 2 μm. Its small particle size and large specific surface area are beneficial to improving the curing efficiency of the magnesium oxide particle A and the electrolyte, and improving the efficiency of isolating the electrolyte of the boron nitride fiber inert choke ring for thermal batteries.

[0038] Furthermore, a fiber modification solution is prepared. The fiber modification solution comprises magnesium oxide particle A, boron oxide, a solvent, and an organic modifier with a mass ratio of (10 - 15):(2 - 8):(60 - 90):(2 - 6).

[0039] The organic modifier is one of acrylate, phenolic resin, furan resin, and sodium carboxymethyl cellulose; the solvent is ethanol or methanol.

[0040] The process of modifying the short - cut boron nitride fiber with the fiber modification solution is as follows: the short - cut boron nitride fiber is impregnated in the fiber modification solution and then dried to obtain the modified boron nitride fiber.

[0041] The beneficial effect of the previous step is that the modification of the boron nitride fiber is achieved, and magnesium oxide particle A adheres to its surface. At the same time, it is beneficial for magnesium oxide particle A to adhere to the surface of the modified boron nitride fiber. Meanwhile, by using one of acrylate, phenolic resin, furan resin, and sodium carboxymethyl cellulose as the organic modifier and ethanol or methanol as the solvent, the fiber modification solution is evenly dispersed, and after the boron nitride fiber is impregnated, magnesium oxide particle A adheres to the fiber surface. At the same time, the modified magnesium oxide particle A layer has a certain porosity, increasing the specific surface area.

[0042] Furthermore, the preparation process of the boron nitride fiber paper pulp is as follows: the modified boron nitride fiber, magnesium oxide particle B, a solvent, and a thickener are mixed in a mass ratio of (1.2 - 2.4):(0.96 - 2.88):(180 - 220):(1.8 - 2.2) to obtain the boron nitride fiber paper pulp.

[0043] The particle size of the magnesium oxide particle B is 5 μm - 15 μm.

[0044] The thickener is one of carboxymethyl cellulose, propylene glycol alginate, methyl cellulose, and sodium starch phosphate.

[0045] The beneficial effect of the previous step is that the boron nitride fiber paper pulp is evenly dispersed, and no agglomeration or other phenomena occur. After filtration and drying, a boron nitride fiber paper blank is formed.

[0046] At the same time, the porosity of the boron nitride fiber inert choke ring for thermal batteries is 60 - 90%.

[0047] Furthermore, the preparation method of the magnesium oxide particle B includes the following steps:

[0048] Prepare the magnesium oxide particle B slurry, granulate the magnesium oxide particle B slurry to obtain the magnesium oxide particle B, and the porosity of the magnesium oxide particle B is 40-60%;

[0049] and / or

[0050] The boron nitride fiber paper slurry further includes melamine, the solvent is kerosene or water, and the mass ratio of the modified boron nitride fiber to melamine is (1.2-2.4):(0.2-1.1); the particle size of the melamine is 5μm-15μm.

[0051] The beneficial effect of the previous step is to realize the preparation of the magnesium oxide particle B;

[0052] Since the boron nitride fiber paper slurry further includes melamine and the solvent is kerosene or water, melamine will adhere to the intersection points of the boron nitride fibers, and then melamine reacts with the boron oxide on the surface of the boron nitride to form boron nitride coated on the surface of the intersection points, thereby further improving the connection strength between the fibers.

[0053] Further, in the preparation process of the magnesium oxide particle B slurry, the mass ratio of magnesium oxide powder, liquid paraffin, water, polymerization monomer, crosslinking agent, and oxidizing agent is (50-70):(1-2):(100-120):(5-10):(0.02-0.1):(1-2);

[0054] The polymerization monomer includes one of methyl acrylate, trimethylolpropane trimethacrylate, diethylene glycol dimethacrylate, and tripropylene glycol diacrylate;

[0055] The crosslinking agent is N,N-methylenebisacrylamide; the initiator is hydrogen peroxide or ammonium persulfate;

[0056] The granulation process is to spray granulate the magnesium oxide particle B slurry, and the temperature of the magnesium oxide particle B slurry after spraying is 80-120°C to obtain a magnesium oxide particle B preform; then heat and react the magnesium oxide particle B preform.

[0057] The heating reaction process is to raise the temperature of the magnesium oxide particle B from room temperature to 100-120°C at a heating rate of 9-10°C / min, then raise the temperature from 100-120°C to 260-300°C at a heating rate of 4-5°C / min; then raise the temperature from 260-300°C to 480-580°C at a heating rate of 2-3°C / min.

[0058] The beneficial effect of the previous step is to realize that the particle size of the magnesium oxide particle B is 5μm-15μm, and the porosity of the magnesium oxide particle B is 40-60%;

[0059] That is, a relatively high porosity is achieved through the content of magnesium oxide powder in the magnesium oxide particle B slurry, and the porosity reaches 40-60%; at the same time, since the magnesium oxide particle B slurry includes liquid paraffin, water, polymerizable monomers, cross-linking agents, and oxidants, the obtained magnesium oxide particle B preform has relatively high strength. Meanwhile, the molecular weight of the organic matter inside the magnesium oxide particle B preform is not too high, that is, the organic matter obtained during monomer polymerization is viscous and has a low molecular weight. The strength of the magnesium oxide particle B preform is further increased through liquid paraffin; through the above heating reaction process, the volatiles in the magnesium oxide particle B are volatilized step by step according to molecular size, avoiding problems such as cracks or cracking in the obtained magnesium oxide particle B.

[0060] Furthermore, the heat treatment process of the boron nitride fiber paper blank is as follows: heating from room temperature to 500-600 °C at a heating rate of 3-5 °C / min, and the heat treatment atmosphere is air; heating from 500-600 °C to 800-1100 °C at a heating rate of 2-3 °C / min, and the heat treatment atmosphere is nitrogen.

[0061] The beneficial effect of the previous step is that it realizes a strong bond of the boron nitride fiber inert flow blocking ring for thermal batteries, and at the same time realizes the reaction of boron oxide and melamine to form boron nitride. Meanwhile, through the heating rates in the above two stages, the phenomenon of a large number of closed pores in the boron nitride fiber inert flow blocking ring for thermal batteries is avoided, which leads to a reduction in the efficiency of the flow blocking ring in isolating electrolytes. Specific embodiments

[0062] To better understand the technical solution of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0063] Example 1:

[0064] This example provides a boron nitride fiber inert flow blocking ring for thermal batteries in one aspect, including a plurality of annular boron nitride fiber papers; the plurality of annular boron nitride fiber papers include boron nitride fibers arranged in a net shape and magnesium oxide particles A attached to the surface of the boron nitride fibers; magnesium oxide particles B are filled in the pores of the boron nitride fibers;

[0065] The porosity of the boron nitride fiber inert flow blocking ring for thermal batteries is 75%; the porosity of the magnesium oxide particles B is 50%; the particle size of the magnesium oxide particles A is 1 μm; the particle size of the magnesium oxide particles B is 10 μm;

[0066] The outer diameter of the boron nitride fiber inert flow blocking ring for thermal batteries is 61 mm, the inner diameter is 59, and the height is 1 mm.

[0067] This example provides a method for preparing a boron nitride fiber inert flow blocking ring for thermal batteries in another aspect, including the following steps:

[0068] Prepare short-cut boron nitride fibers;

[0069] Prepare a fiber modification solution, the fiber modification solution including magnesium oxide particles A and boron oxide;

[0070] Modify the short-cut boron nitride fibers with the fiber modification solution to obtain modified boron nitride fibers; the specific process is as follows: prepare a fiber modification solution, the fiber modification solution including magnesium oxide particles A, boron oxide, a solvent, and an organic modifier in a mass ratio of 12:5:75:4;

[0071] The organic modifier is acrylate; the solvent is ethanol;

[0072] The process of modifying the short-cut boron nitride fibers with the fiber modification solution is as follows: impregnate the short-cut boron nitride fibers in the fiber modification solution and then dry them to obtain the modified boron nitride fibers; the length of the short-cut boron nitride fibers is 10 mm; the particle size of the magnesium oxide particles A is 1 μm; the mass ratio of the short-cut boron nitride fibers to the magnesium oxide particles A is 1:1.

[0073] Prepare boron nitride fiber paper pulp; the process of preparing the boron nitride fiber paper pulp is as follows: mix the modified boron nitride fibers, magnesium oxide particles B, water, and a thickener in a mass ratio of 1.8:1.98:200:2 to obtain the boron nitride fiber paper pulp; the particle size of the magnesium oxide particles B is 10 μm;

[0074] The thickener is carboxymethyl cellulose;

[0075] The preparation method of the magnesium oxide particles B includes the following steps: prepare a magnesium oxide particle B slurry, and granulate the magnesium oxide particle B slurry to obtain the magnesium oxide particles B, the porosity of the magnesium oxide particles B being 50%;

[0076] The process of preparing the magnesium oxide particle B slurry is as follows: mix magnesium oxide powder, liquid paraffin, water, a polymerization monomer, a cross-linking agent, and an oxidizing agent in a mass ratio of 60:1.5:110:7.5:0.51:1.5;

[0077] The polymerization monomer includes trimethylolpropane trimethacrylate;

[0078] The cross-linking agent is N,N-methylenebisacrylamide; the initiator is hydrogen peroxide;

[0079] The granulation process is as follows: perform spray granulation on the magnesium oxide particle B slurry, the temperature of the magnesium oxide particle B slurry after spraying being 100°C, to obtain a magnesium oxide particle B preform; then perform a heating reaction on the magnesium oxide particle B preform;

[0080] The heating reaction process is as follows: The magnesium oxide particles B are heated from room temperature to 110 °C at a heating rate of 9.5 °C / min, then heated from 110 °C to 280 °C at a heating rate of 4.5 °C / min; then heated from 280 °C to 530 °C at a heating rate of 2.5 °C / min.

[0081] The boron nitride fiber paper slurry is made into a paper blank by papermaking, filtration, and drying and forming; the drying temperature is 100 °C; the length and width dimensions of the boron nitride fiber paper blank can reach 900 * 900 mm;

[0082] Then, the boron nitride fiber paper blank is heat-treated to obtain a boron nitride fiber paper; a part of the heat treatment process is carried out in a nitrogen atmosphere; the heat treatment process of the boron nitride fiber paper blank is to be heated from room temperature to 550 °C at a heating rate of 4 °C / min, and the heat treatment atmosphere is air.

[0083] Several layers of boron nitride fiber paper are stamped to obtain a boron nitride fiber inert choke ring for thermal batteries.

[0084] Example 2:

[0085] The same content as in Example 1 will not be repeated here; the different solutions from Example 1 are as follows:

[0086] One aspect of this example provides a boron nitride fiber inert choke ring for thermal batteries, and boron nitride is coated on the intersection points of the boron nitride fibers.

[0087] The porosity of the boron nitride fiber inert choke ring for thermal batteries is 65%; the porosity of the magnesium oxide particles B is 45%; the particle size of the magnesium oxide particles A is 0.05 μm; the particle size of the magnesium oxide particles B is 8 μm;

[0088] The outer diameter dimension of the boron nitride fiber inert choke ring for thermal batteries is 24 mm, the inner diameter dimension is 22, and the height is 1.5 mm.

[0089] Another aspect of this example provides a preparation method of a boron nitride fiber inert choke ring for thermal batteries, including the following steps:

[0090] The boron nitride fiber paper slurry further includes melamine, and the solvent is kerosene; the preparation process of the boron nitride fiber paper slurry is to mix modified boron nitride fibers, magnesium oxide particles B, melamine, kerosene, and a thickener in a mass ratio of 1.4:1.08:0.3:185:1.9 to obtain the boron nitride fiber paper slurry; the particle size of the melamine is 7 μm; the particle size of the magnesium oxide particles B is 7 μm;

[0091] The thickening agent is propylene glycol alginate; the porosity of the magnesium oxide particles B is 45%; the short-cut boron nitride fibers are modified by the fiber modification solution to obtain modified boron nitride fibers; the specific process is as follows: prepare the fiber modification solution, and the fiber modification solution includes magnesium oxide particles A, boron oxide, a solvent, and an organic modifier in a mass ratio of 11:3:65:3;

[0092] The organic modifier is furan resin; the solvent is methanol;

[0093] The length of the short-cut boron nitride fibers is 1.5 mm; the particle size of the magnesium oxide particles A is 0.05 μm; the mass ratio of the short-cut boron nitride fibers to the magnesium oxide particles A is 1:0.9.

[0094] The process for preparing the magnesium oxide particles B slurry is as follows: magnesium oxide powder, liquid paraffin, water, a polymerization monomer, a cross-linking agent, and an oxidizing agent are in a mass ratio of 55:1.2:102:6:0.03:1.2;

[0095] The polymerization monomer includes diethylene glycol diacrylate;

[0096] The initiator is ammonium persulfate;

[0097] The granulation process is as follows: the magnesium oxide particles B slurry is spray granulated, and the temperature of the sprayed magnesium oxide particles B slurry is 90°C to obtain a magnesium oxide particles B preform; then the magnesium oxide particles B preform is subjected to a heating reaction;

[0098] The heating reaction process is as follows: the magnesium oxide particles B are heated from room temperature to 105°C at a heating rate of 9.2°C / min, and then from 105°C to 270°C at a heating rate of 4.2°C / min; then from 270°C to 490°C at a heating rate of 2.2°C / min.

[0099] The boron nitride fiber paper slurry is subjected to papermaking, filtration, and drying and forming to obtain a boron nitride fiber paper blank; the drying temperature is 90°C; the length and width dimensions of the boron nitride fiber paper blank can reach 650*650 mm;

[0100] Then the boron nitride fiber paper blank is heat-treated to obtain a boron nitride fiber paper; a part of the heat treatment process is carried out in a nitrogen atmosphere; the process of heat-treating the boron nitride fiber paper blank is as follows: it is heated from room temperature to 510°C at a heating rate of 3.5°C / min, and the heat treatment atmosphere is air; from 510°C to 950°C at a heating rate of 2.5°C / min, and the heat treatment atmosphere is nitrogen.

[0101] Example 3:

[0102] The content that is the same as that in Embodiment 1 will not be elaborated here; the different solutions in this embodiment from those in Embodiment 1 are as follows:

[0103] One aspect of this embodiment provides a boron nitride fiber inert flow-blocking ring for a thermal battery, and boron nitride coats the intersection points of the boron nitride fibers.

[0104] The porosity of the boron nitride fiber inert flow-blocking ring for the thermal battery is 85%; the porosity of the magnesium oxide particle B is 55%; the particle size of the magnesium oxide particle A is 1.5 μm; the particle size of the magnesium oxide particle B is 12.5 μm;

[0105] The outer diameter dimension of the boron nitride fiber inert flow-blocking ring for the thermal battery is 95 mm, the inner diameter dimension is 90, and the height is 6 mm.

[0106] Another aspect of this embodiment provides a preparation method for a boron nitride fiber inert flow-blocking ring for a thermal battery, including the following steps:

[0107] The boron nitride fiber paper slurry further includes melamine, and the solvent is kerosene; the preparation process of the boron nitride fiber paper slurry is to mix modified boron nitride fibers, magnesium oxide particle B, melamine, kerosene, and a thickening agent in a mass ratio of 2.2:2.78:0.9:210:2.1 to obtain the boron nitride fiber paper slurry; the particle size of the melamine is 13 μm; the particle size of the magnesium oxide particle B is 12.5 μm;

[0108] The thickening agent is methyl cellulose; the porosity of the magnesium oxide particle B is 55%;

[0109] The short-cut boron nitride fibers are modified by the fiber modification solution to obtain modified boron nitride fibers; the specific process is to prepare the fiber modification solution, and the fiber modification solution includes magnesium oxide particle A, boron oxide, a solvent, and an organic modifier in a mass ratio of 14:(2 - 8):86:5;

[0110] The organic modifier is sodium carboxymethyl cellulose; the solvent is methanol;

[0111] The length of the short-cut boron nitride fibers is 18 mm; the particle size of the magnesium oxide particle A is 1.5 μm; the mass ratio of the short-cut boron nitride fibers to the magnesium oxide particle A is 1:1.1.

[0112] The preparation process of the magnesium oxide particle B slurry is to mix magnesium oxide powder, liquid paraffin, water, a polymerization monomer, a cross-linking agent, and an oxidizing agent in a mass ratio of 65:1.8:118:8.5:0.85:1.8;

[0113] The polymerization monomer includes tripropylene glycol diacrylate;

[0114] The initiator is ammonium persulfate;

[0115] The granulation process is as follows: spray granulate the magnesium oxide particle B slurry, the temperature of the magnesium oxide particle B slurry after spraying is 110 °C, to obtain a magnesium oxide particle B preform; then carry out a heating reaction on the magnesium oxide particle B preform;

[0116] The heating reaction process is as follows: heat the magnesium oxide particle B from room temperature to 118 °C, with a heating rate of 9.8 °C / min, then heat from 118 °C to 290 °C, with a heating rate of 4.8 °C / min; then heat from 290 °C to 570 °C, with a heating rate of 2.9 °C / min.

[0117] Carry out papermaking, filtering, and drying and forming on the boron nitride fiber paper slurry to obtain a boron nitride fiber paper blank; the drying temperature is 115 °C; the length and width dimensions of the boron nitride fiber paper blank can reach 1150 * 1150 mm;

[0118] Then carry out heat treatment on the boron nitride fiber paper blank to obtain a boron nitride fiber paper; part of the heat treatment process is carried out in a nitrogen atmosphere; the heat treatment process of the boron nitride fiber paper blank is as follows: heat from room temperature to 590 °C, with a heating rate of 4.8 °C / min, and the heat treatment atmosphere is air; heat from 590 °C to 1000 °C, with a heating rate of 2.8 °C / min, and the heat treatment atmosphere is nitrogen.

[0119] The above description is only the preferred embodiments of the present application and the description of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features have similar functions to those disclosed in the present application (but not limited to).

Claims

1. A boron nitride fiber inert flow-blocking ring for a thermal battery, characterized in that, It includes several annular boron nitride fiber papers; Several of the said annular boron nitride fiber papers include boron nitride fibers arranged in a net shape and magnesium oxide particles A attached to the surface of the boron nitride fibers; Magnesium oxide particles B are filled in the pores of the boron nitride fibers.

2. The inert flow blocking ring made of boron nitride fiber for thermal battery according to claim 1, characterized in that The outer diameter dimension of the boron nitride fiber inert choke ring for thermal battery is 23 - 100 mm, the inner diameter dimension is 20 - 97, and the height is 1.4 - 7 mm.

3. The boron nitride fiber inert choke ring for thermal battery according to claim 1, the porosity of the boron nitride fiber inert choke ring for thermal battery is 60 - 90%; The porosity of the magnesium oxide particles B is 40 - 60%; The particle size of the magnesium oxide particles A is 0.01 μm - 2 μm; the particle size of the magnesium oxide particles B is 5 μm - 15 μm; and / or The intersection points of the boron nitride fibers are coated with boron nitride.

4. A preparation method of a boron nitride fiber inert flow blocking ring for a thermal battery, characterized in that, It includes the following steps: Prepare chopped boron nitride fibers; Prepare a fiber modification solution, and the fiber modification solution includes magnesium oxide particles A and boron oxide; Modify the chopped boron nitride fibers with the fiber modification solution to obtain modified boron nitride fibers; Prepare a boron nitride fiber paper slurry; Perform papermaking, filtration, and drying and shaping on the boron nitride fiber paper slurry to obtain a boron nitride fiber paper blank; Then perform heat treatment on the boron nitride fiber paper blank to obtain a boron nitride fiber paper; Press several layers of boron nitride fiber papers to obtain a boron nitride fiber inert choke ring for thermal battery.

5. The preparation method of the boron nitride fiber inert choke ring for thermal battery according to claim 1, characterized in that, The length of the chopped boron nitride fibers is 0.2 mm - 20 mm; The particle size of the magnesium oxide particles A is 0.01 μm - 2 μm; The mass ratio of the chopped boron nitride fibers to the magnesium oxide particles A is 1:(0.8 - 1.2).

6. The preparation method of the boron nitride fiber inert flow blocking ring for thermal battery according to claim 1, characterized in that, Prepare a fiber modification solution, and the fiber modification solution includes magnesium oxide particles A, boron oxide, a solvent, and an organic modifier with a mass ratio of (10 - 15):(2 - 8):(60 - 90):(2 - 6); The organic modifier is one of acrylate, phenolic resin, furan resin, and sodium carboxymethylcellulose; the solvent is ethanol or methanol; The process of modifying the chopped boron nitride fibers with the fiber modification solution is to impregnate the chopped boron nitride fibers in the fiber modification solution and then dry them to obtain the modified boron nitride fibers.

7. The preparation method of the boron nitride fiber inert choke ring for thermal battery according to claim 1, characterized in that, The preparation process of the boron nitride fiber paper slurry is to mix the modified boron nitride fibers, magnesium oxide particles B, a solvent, and a thickener in a mass ratio of (1.2 - 2.4):(0.96 - 2.88):(180 - 220):(1.8 - 2.2) to obtain the boron nitride fiber paper slurry; The particle size of the magnesium oxide particles B is 5 μm - 15 μm; The thickener is one of carboxymethylcellulose, propylene glycol alginate, methylcellulose, and sodium starch phosphate.

8. The preparation method of the boron nitride fiber inert flow blocking ring for thermal battery according to claim 7, characterized in that, The preparation method of the magnesium oxide particles B includes the following steps: Prepare a magnesium oxide particles B slurry, granulate the magnesium oxide particles B slurry to obtain the magnesium oxide particles B, and the porosity of the magnesium oxide particles B is 40 - 60%; and / or The boron nitride fiber paper pulp further includes melamine, the solvent is kerosene or water, and the mass ratio of the modified boron nitride fiber to melamine is (1.2 - 2.4):(0.2 - 1.1); the particle size of the melamine is 5μm - 15μm.

9. The preparation method of the boron nitride fiber inert choke ring for thermal battery according to claim 8, characterized in that, The preparation process of the magnesium oxide particle B slurry is as follows: the mass ratio of magnesium oxide powder, liquid paraffin, water, polymerization monomer, crosslinking agent, and oxidizing agent is (50 - 70):(1 - 2):(100 - 120):(5 - 10):(0.02 - 0.1):(1 - 2); The polymerization monomer includes one of methyl acrylate, trimethylolpropane trimethacrylate, diethylene glycol diacrylate, and tripropylene glycol diacrylate; The crosslinking agent is N,N - methylenebisacrylamide; the initiator is hydrogen peroxide or ammonium persulfate; The granulation process is as follows: the magnesium oxide particle B slurry is spray - granulated, and the temperature of the magnesium oxide particle B slurry after spraying is 80 - 120°C to obtain a magnesium oxide particle B preform; then the magnesium oxide particle B preform is subjected to a heating reaction; The heating reaction process is as follows: the magnesium oxide particle B is heated from room temperature to 100 - 120°C at a heating rate of 9 - 10°C / min, and then heated from 100 - 120°C to 260 - 300°C at a heating rate of 4 - 5°C / min; then heated from 260 - 300°C to 480 - 580°C at a heating rate of 2 - 3°C / min.

10. The preparation method of the boron nitride fiber inert choke ring for thermal battery according to claim 8, characterized in that, The heat - treatment process of the boron nitride fiber paper blank is as follows: heated from room temperature to 500 - 600°C at a heating rate of 3 - 5°C / min, and the heat - treatment atmosphere is air; heated from 500 - 600°C to 800 - 1100°C at a heating rate of 2 - 3°C / min, and the heat - treatment atmosphere is nitrogen.