阅读说明：本技术 一种热电池用多孔陶瓷纤维隔膜材料及其制备方法 (Porous ceramic fiber diaphragm material for thermal battery and preparation method thereof ) 是由 龙金 夏堃宇 胡健 王建勇 郭灏 唐立成 邹睿 于 2021-01-18 设计创作，主要内容包括：本发明涉及一种热电池用多孔陶瓷纤维隔膜材料及其制备方法。本发明的隔膜材料由陶瓷纤维和无机粘结剂组成。本发明的隔膜材料可广泛应用于大功率输出的高电压热电池以及大脉冲型热电池之中,这两种类型的热电池可作为鱼雷、潜射核武、高超声速巡航导弹、高超声速飞行器和临近空间飞行器等武器装备的主电源使用。(The invention relates to a porous ceramic fiber diaphragm material for a thermal battery and a preparation method thereof. The separator material of the present invention is composed of ceramic fibers and an inorganic binder. The diaphragm material can be widely applied to high-voltage thermal batteries with high power output and large pulse thermal batteries, and the two types of thermal batteries can be used as main power sources of weaponry such as torpedoes, submarine nuclear wars, hypersonic cruise missiles, hypersonic aircrafts, near space aircrafts and the like.)

1. A porous ceramic fiber diaphragm material for a thermal battery is composed of ceramic fibers and an inorganic binder.

2. Separator material according to claim 1, characterized in that the ceramic fibres represent 50-80%, preferably 50% by weight of the separator material.

3. Separator material according to claim 1 or 2, characterized in that the inorganic binder constitutes 20-50%, preferably 50% of the separator material in weight percentage.

4. Diaphragm material according to any of claims 1 to 3, wherein the ceramic fibers are selected from one or more of alumina fibers, aluminosilicate fibers, silicon carbide fibers and boron nitride fibers, preferably aluminosilicate fibers, more preferably mullite ceramic fibers.

5. Separator material according to any of claims 1 to 4, characterized in that the inorganic binder is selected from the group consisting of alumina binders, polysiloxane binders and polycarbosilane binders, preferably alumina binders.

6. Membrane material as claimed in any of the claims 1-5, wherein the ceramic fibres have a diameter of 1-4 microns, preferably 2-3 microns;

preferably, the quantitative amount of the membrane material is 60-80g/m²Preferably 70g/m²；

Preferably, the thickness of the diaphragm material is 0.2mm to 0.3 mm.

7. A method of preparing a porous ceramic fiber separator material for a thermal battery, the method comprising the steps of:

(1) weighing ceramic fibers and bonding fibers according to the quantitative requirements and the areas of the porous ceramic fiber diaphragm material, mixing the weighed ceramic fibers and bonding fibers, putting the mixture into water, and defibering the mixture in a defibering machine to obtain uniform fiber suspension;

(2) forming the fiber suspension obtained in the step (1) by a wet method to prepare a non-woven fabric ceramic fiber diaphragm, and then drying;

(3) immersing the non-woven fabric ceramic fiber diaphragm dried in the step (2) into an inorganic binder solution, taking out and drying;

(4) and (4) carrying out heat treatment on the non-woven fabric ceramic fiber diaphragm dried in the step (3) to obtain the non-woven fabric ceramic fiber diaphragm.

8. The method according to claim 7, wherein in the step (1), the ceramic fiber accounts for 95-97 wt%, and the bonding fiber accounts for 3-5 wt%; preferably, the ceramic fibers account for 95% and the binder fibers account for 5% by weight.

9. The production method according to claim 7 or 8, wherein in step (1), the ceramic fibers are selected from one or more of alumina fibers, aluminosilicate fibers, silicon carbide fibers and boron nitride fibers, preferably aluminosilicate fibers, more preferably mullite ceramic fibers;

preferably, in step (1), the binding fibers are selected from the group consisting of PET, PVA, ES, PP and PE, preferably PE;

preferably, in step (2), the temperature of the drying is 90 ℃ to 95 ℃.

10. The method according to any one of claims 7 to 9, wherein in the step (3), the inorganic binder solution is an aluminum isopropoxide solution, and the method is as follows: weighing 8g of aluminum isopropoxide, adding the aluminum isopropoxide into 70ml of deionized water, stirring and hydrolyzing for 2h at the water bath temperature of 85 ℃, then adding dilute nitric acid with the concentration of 2mol/L, and continuously stirring for 1h to obtain the aluminum isopropoxide-containing aqueous solution;

preferably, in the step (3), the temperature of the drying is 80-100 ℃;

preferably, in the step (3), the non-woven fabric ceramic fiber membrane dried in the step (2) is immersed into an inorganic binder solution until the membrane is completely immersed, preferably for 5 min;

preferably, in the step (4), the heat treatment is carried out in a tube furnace or a muffle furnace at a heating rate of 3 ℃/min to 600 ℃ in an air atmosphere, and the temperature is kept for 5h and then the product is naturally cooled to room temperature.

Technical Field

The invention belongs to the technical field of thermal battery diaphragm materials, and particularly relates to a porous ceramic fiber diaphragm material for a thermal battery and a preparation method thereof.

Background

The thermal battery is also called a thermal activation battery, and is a reserve battery which mainly takes solid molten salt as electrolyte, ignites an internal heat source by means of electric activation or mechanical activation and the like, the heating system of the battery after activation reaches the working temperature (the working temperature is between 350 ℃ and 550 ℃), the solid molten salt electrolyte is converted from a solid state into a liquid state at the moment, and therefore the anode and the cathode react with the electrolyte to generate working voltage.

The thermal battery mainly comprises a positive electrode, a negative electrode, a heat insulating material, a diaphragm material (diaphragm, electrolyte) and the like. The purpose of developing these materials is to improve the output power and safety of thermal batteries, so as to meet the requirements of military weapons. The lithium alloy/iron disulfide thermal battery (such as Li-Al/FeS2, Li-Si/FeS2 and Li-B/FeS2) is one of the most advanced thermal battery systems at present, and the development of anode and cathode materials is slow in recent 30 years, so that the improvement of the output power and other performances of the thermal battery by researching the anode and cathode materials becomes more and more difficult. The interior of the thermal battery is formed by stacking wafer-shaped materials such as a positive electrode, a negative electrode, a diaphragm, a heating plate and the like layer by layer. In order to increase the power and energy density of thermal batteries as much as possible, it is desirable to reduce the thickness of the parts as much as possible. The degree of thinness of the positive electrode and the negative electrode is determined by the amount of the electrode active material required as expected, but the internal resistance of the battery can be lowered by making the separator thinner. At present, the diaphragm of the thermal battery in China is formed by simply and mechanically pressing magnesium oxide powder mixed electrolyte powder through a pressure device. Due to the low mechanical adaptability of the magnesium oxide powder tabletting membrane, the membrane becomes fragile especially when the thickness of the membrane is less than 0.5mm and the diameter is more than 5 cm. The thicker magnesium oxide tabletting diaphragm increases the internal resistance of the thermal battery and reduces the output power of the thermal battery. Smaller membranes also prevent the design from producing larger unit thermal cells. And the magnesium oxide tabletting diaphragm has the risk of leakage of molten electrolyte under the condition of long-time discharge, thereby causing the problems of short circuit and the like caused by contact of the anode and the cathode of the thermal battery.

In order to improve the safety performance and output power of the thermal battery, a porous ceramic fiber diaphragm can be used, wherein the ceramic fiber is inorganic fiber, and the ceramic fiber is difficult to disperse and form in the wet forming process due to the characteristics of high brittleness, high strength and the like, and the ceramic fiber with poor dispersibility can cause the problems of poor uniformity, low local strength, difficult subsequent processing and the like of the prepared ceramic diaphragm material. After the ceramic fiber diaphragm is formed by a wet method, if the diaphragm works at 550 ℃ after the organic adhesive is used, the diaphragm does not have corresponding strength any more, so that normal, safe and efficient discharge of the thermal battery cannot be guaranteed. Therefore, the wet forming process and the reinforcing process of the ceramic fiber diaphragm are important.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a porous ceramic fiber diaphragm material for a thermal battery and a preparation method thereof.

The diaphragm material can be widely applied to high-voltage thermal batteries with high power output and large pulse thermal batteries, and the two types of thermal batteries can be used as main power sources of weaponry such as torpedoes, submarine nuclear wars, hypersonic cruise missiles, hypersonic aircrafts, near space aircrafts and the like.

The foregoing object of the present invention is achieved by the following means.

In one aspect, the present invention provides a porous ceramic fiber separator material for a thermal battery, the separator material consisting of ceramic fibers and an inorganic binder.

Preferably, the ceramic fibers comprise 50% to 80%, preferably 50%, by weight of the separator material.

Preferably, the inorganic binder accounts for 20-50% of the separator material, preferably 50% of the separator material by weight percentage.

Preferably, the ceramic fibers are selected from one or more of alumina fibers, aluminosilicate fibers, silicon carbide fibers and boron nitride fibers, preferably aluminosilicate fibers, more preferably mullite ceramic fibers.

Preferably, the ceramic fibers have a diameter of 1 to 4 microns, preferably 2 to 3 microns.

In a specific embodiment, the ceramic fibers are mullite ceramic fibers having a diameter of 2 to 3 microns.

Preferably, the inorganic binder is selected from the group consisting of alumina, polysiloxane, and polycarbosilane binders, preferably an alumina binder.

Preferably, the quantitative amount of the membrane material is 60-80g/m²Preferably 70g/m²。

Preferably, the thickness of the diaphragm material is 0.2mm to 0.3 mm.

In another aspect, the present invention provides a method for preparing a porous ceramic fiber separator material for a thermal battery, comprising the steps of:

(1) weighing ceramic fibers according to the quantitative requirements and the areas of the porous ceramic fiber diaphragm material, mixing the weighed ceramic fibers and bonding fibers, putting the mixture into water, and defibering the mixture in a defibering machine to obtain uniform fiber suspension;

(2) forming the fiber suspension obtained in the step (1) by a wet method to prepare a non-woven fabric ceramic fiber diaphragm, and then drying;

(3) immersing the non-woven fabric ceramic fiber diaphragm dried in the step (2) into an inorganic binder solution, taking out and drying;

(4) and (4) carrying out heat treatment on the non-woven fabric ceramic fiber diaphragm dried in the step (3) to obtain the non-woven fabric ceramic fiber diaphragm.

Preferably, in the step (1), the ceramic fiber accounts for 95-97% and the bonding fiber accounts for 3-5% by weight percentage; preferably, the ceramic fibers account for 95% and the binder fibers account for 5% by weight.

Preferably, in step (1), the ceramic fibers are selected from one or more of alumina fibers, aluminosilicate fibers, silicon carbide fibers and boron nitride fibers, preferably aluminosilicate fibers, more preferably mullite ceramic fibers;

preferably, in step (1), the ceramic fibers have a diameter of 1 to 4 microns, preferably 2 to 3 microns.

Preferably, in step (1), the binding fibers are selected from the group consisting of PET, PVA, ES, PP and PE, preferably PE.

Preferably, in step (2), the temperature of the drying is 90 ℃ to 95 ℃.

Preferably, in the step (3), the inorganic binder solution is an aluminum isopropoxide solution, and the preparation method thereof is as follows: weighing 8g of aluminum isopropoxide, adding the aluminum isopropoxide into 70ml of deionized water, stirring and hydrolyzing for 2h at the water bath temperature of 85 ℃, then adding dilute nitric acid with the concentration of 2mol/L, and continuously stirring for 1h to obtain the aluminum isopropoxide.

Preferably, in the step (3), the temperature of the drying is 80-100 ℃.

Preferably, in the step (3), the non-woven fabric ceramic fiber membrane dried in the step (2) is immersed in the inorganic binder solution until the membrane is completely immersed, and the immersion is preferably performed for 5 min.

Preferably, in the step (4), the heat treatment is carried out in a tube furnace or a muffle furnace at a heating rate of 3 ℃/min to 600 ℃ in an air atmosphere, and the temperature is kept for 5h and then the product is naturally cooled to room temperature.

In one embodiment, the method of preparing the porous ceramic fiber separator material for a thermal battery comprises the steps of:

(1) weighing mullite ceramic fibers and bonding fibers with the diameter of 2-3 microns according to the quantitative requirements and the area of the porous ceramic fiber diaphragm material, wherein the ceramic fibers account for 95 percent and the bonding fibers account for 5 percent in percentage by weight, mixing the ceramic fibers and the bonding fibers, putting the mixture into water, and defibering the mixture in a defibering machine to obtain uniform fiber suspension;

(2) the fiber suspension is prepared into a non-woven fabric ceramic fiber diaphragm through wet forming, and then the non-woven fabric ceramic fiber diaphragm is placed in a dryer for drying.

(3) An aluminum isopropoxide binder solution was prepared according to the following method: weighing 8g of aluminum isopropoxide, adding the aluminum isopropoxide into 70ml of deionized water, stirring and hydrolyzing at the water bath temperature of 85 ℃ for 2h, adding dilute nitric acid with the concentration of 2mol/L, and continuously stirring for 1h to obtain the aluminum isopropoxide-containing composite membrane, then immersing the non-woven ceramic fiber membrane dried in the step (2) into the prepared aluminum isopropoxide binder solution, taking out the non-woven ceramic fiber membrane, and putting the non-woven ceramic fiber membrane into an oven for drying.

(4) And (4) putting the dried non-woven fabric ceramic fiber diaphragm into a muffle furnace for heat treatment to obtain the ceramic fiber diaphragm.

Compared with the prior art, the ceramic fiber diaphragm material has at least the following advantages:

(1) according to the invention, the bonding fiber is added in the preparation process to bond the ceramic fiber, so that the ceramic fiber diaphragm has certain treatment strength. The ceramic fiber is inorganic fiber, no interaction force exists between the fibers, if the ceramic fiber is directly formed by a wet method, the processing strength is extremely low, the application finds that the ceramic fiber is very favorable for forming the diaphragm paper-shaped handsheet material by adding the bonding fiber during the wet forming of the ceramic fiber, the thickness, the porosity and other basic properties of the diaphragm can be controlled by adjusting the fiber proportion and the type of the handsheet, and the handsheet can be cut into a desired shape at will.

(2) Considering that the bonding fiber can be decomposed at high temperature to cause the membrane to be scattered, the invention further adopts the alumina inorganic bonding agent to strengthen the membrane and improve the high temperature resistance of the membrane to 800 ℃, namely the membrane still has the tensile strength of 200n/m at 800 ℃.

(3) The processing strength of the diaphragm at high temperature is favorable for ensuring that the diaphragm does not fall apart while fixing and adsorbing electrolyte, thereby ensuring the safety performance of the battery.

(4) This application adopts the ceramic fiber that the diameter is thinner, and the diaphragm that obtains under the same ration is thinner, and discharge performance is also better.

Drawings

FIG. 1: SEM image of ceramic fiber added with bonding fiber;

FIG. 2: TG and DSC curves of the product obtained in example 1.

FIG. 3: the test result of the pulse discharge performance of the ceramic material is shown in the figure A, wherein the diameter of the ceramic fiber is 2-3 microns, and the figure B is the diameter of the ceramic fiber is 5-7 microns.

Detailed Description

The technical solution of the present invention will be further described below with reference to specific embodiments.

Example 1 porous ceramic fiber separator Material for thermal batteries

A porous ceramic fiber diaphragm material for thermal battery, wherein the quantitative of the diaphragm material is 70g/m²The diaphragm material method comprises the following steps:

(1) weighing mullite ceramic fiber and bonding fiber (PE) with the diameter of 2-3 microns according to the quantitative requirement and the area of the porous ceramic fiber diaphragm material, wherein the ceramic fiber accounts for 95% and the bonding fiber (PE) accounts for 5% in percentage by weight, mixing the ceramic fiber and the bonding fiber, putting the mixture into water, and defibering the mixture in a defibering machine to obtain uniform fiber suspension.

(2) And (2) preparing a non-woven fabric ceramic fiber diaphragm from the fiber suspension obtained in the step (1) through wet forming, and then drying the non-woven fabric ceramic fiber diaphragm in a dryer at the temperature of 95 ℃ to obtain the ceramic fiber added with the bonding fiber, wherein an SEM image of the ceramic fiber is shown in FIG. 1.

(3) Weighing 8g of aluminum isopropoxide, adding the aluminum isopropoxide into 70ml of deionized water, stirring and hydrolyzing at the water bath temperature of 85 ℃ for 2h, adding dilute nitric acid with the concentration of 2mol/L, continuously stirring for 1h to obtain an aluminum isopropoxide solution, immersing the non-woven fabric ceramic fiber membrane dried in the step (2) into the aluminum isopropoxide solution for 5min, taking out after complete infiltration, and putting the non-woven fabric ceramic fiber membrane into an oven to dry at the temperature of 100 ℃.

(4) And (3) putting the dried non-woven fabric ceramic fiber diaphragm into a tubular furnace, heating to 600 ℃ at the heating rate of 3 ℃/min in the air atmosphere, preserving the heat for 5 hours, and naturally cooling to room temperature to obtain the non-woven fabric ceramic fiber diaphragm.

The DSC curve of the obtained product is shown in FIG. 2.

Example 2 porous ceramic fiber separator Material for thermal batteries

A porous ceramic fiber diaphragm material for thermal battery, wherein the quantitative of the diaphragm material is 80g/m²The diaphragm material method comprises the following steps:

(1) respectively weighing mullite ceramic fiber and bonding fiber (PE) with the diameter of 2-3 microns according to the quantitative requirement and the area of the porous ceramic fiber diaphragm material, wherein the mullite ceramic fiber accounts for 95% and the bonding fiber (PE) accounts for 5% in percentage by weight, mixing the ceramic fiber and the bonding fiber, putting the mixture into water, and defibering the mixture in a defibering machine to obtain two uniform fiber suspensions;

(2) and (3) preparing the non-woven fabric ceramic fiber diaphragm by wet forming the two parts of the fiber suspension, and then drying the non-woven fabric ceramic fiber diaphragm in a dryer.

(3) An aluminum isopropoxide binder solution was prepared according to the following method: weighing 8g of aluminum isopropoxide, adding the aluminum isopropoxide into 70ml of deionized water, stirring and hydrolyzing at the water bath temperature of 85 ℃ for 2h, adding dilute nitric acid with the concentration of 2mol/L, and continuously stirring for 1h to obtain the aluminum isopropoxide-containing composite membrane, then immersing the non-woven ceramic fiber membrane dried in the step (2) into the prepared aluminum isopropoxide binder solution, taking out the non-woven ceramic fiber membrane, and putting the non-woven ceramic fiber membrane into an oven for drying.

(4) And (4) putting the dried non-woven fabric ceramic fiber diaphragm into a muffle furnace for heat treatment to obtain the ceramic fiber diaphragm.

The DSC curve of the product obtained is similar to that of figure 2.

Example 3 porous ceramic fiber separator Material for thermal batteries

A porous ceramic fiber diaphragm material for thermal battery, wherein the quantitative of the diaphragm material is 80g/m²The diaphragm material method comprises the following steps:

(1) respectively weighing mullite ceramic fiber and bonding fiber (PE) with the diameter of 5-7 microns according to the quantitative requirement and the area of the porous ceramic fiber diaphragm material, wherein the mullite ceramic fiber accounts for 95% and the bonding fiber (PE) accounts for 5% in percentage by weight, mixing the ceramic fiber and the bonding fiber, putting the mixture into water, and defibering the mixture in a defibering machine to obtain two uniform fiber suspensions;

(2) and (3) preparing the non-woven fabric ceramic fiber diaphragm by wet forming the two parts of the fiber suspension, and then drying the non-woven fabric ceramic fiber diaphragm in a dryer.

(3) An aluminum isopropoxide binder solution was prepared according to the following method: weighing 8g of aluminum isopropoxide, adding the aluminum isopropoxide into 70ml of deionized water, stirring and hydrolyzing at the water bath temperature of 85 ℃ for 2h, adding dilute nitric acid with the concentration of 2mol/L, and continuously stirring for 1h to obtain the aluminum isopropoxide-containing composite membrane, then immersing the non-woven ceramic fiber membrane dried in the step (2) into the prepared aluminum isopropoxide binder solution, taking out the non-woven ceramic fiber membrane, and putting the non-woven ceramic fiber membrane into an oven for drying.

(4) And (4) putting the dried non-woven fabric ceramic fiber diaphragm into a muffle furnace for heat treatment to obtain the ceramic fiber diaphragm.

Example 4 testing of tensile Strength

This example tested the tensile strength of three samples:

sample 1: the only difference from example 1 is that step (1) does not add bonding fibers;

sample 2: the difference from example 1 is only that the heat treatment of step (4) is not performed;

sample 3: the technical solution of example 1.

Wherein the tensile strength is measured by an L & W tensile strength tester, in accordance with the G/BT453-2002 standard. The results are shown in the following table:

diaphragm sample	Sample 1	Sample 2	Sample 3
				Tensile strength N/M	Neglect to count	700	400

As can be seen, the ceramic fibers are inorganic fibers, no interaction force exists between the fibers, and the processing strength is extremely low if the fibers are directly formed by a wet method. After the addition of the binder fibers, it was found that the ceramic fibers were very advantageous for forming into a separator paper-like handsheet material, and the handsheet could be cut into a desired shape by controlling basic properties such as thickness and porosity of the separator by adjusting the fiber ratio and type.

The addition of the bonding fibers ensures that the diaphragm has corresponding treatment strength at normal room temperature, however, the bonding fibers can be decomposed at high temperature to cause the diaphragm to be scattered, and the alumina precursor is adopted to reinforce the diaphragm, so that the high-temperature resistance of the diaphragm is improved to 800 ℃, namely the diaphragm still has the tensile strength of 400n/m at 800 ℃. The processing strength of the diaphragm at high temperature is favorable for ensuring that the diaphragm does not fall apart when the diaphragm fixedly adsorbs electrolyte, thereby ensuring the safety performance of the battery.

Example 5 testing of pulsed discharge Performance

The ternary electrolyte LiF-LiCl-LiBr was weighed (0.3g electrolyte) in a drying chamber with a humidity of less than 3% and uniformly coated on the ceramic fiber separator materials of examples 2 and 3, and the electrolyte was heated and melted at a temperature of 500 degrees celsius for 5 min. And (3) completely adsorbing 0.3g of molten electrolyte by the diaphragm, and then cooling to obtain the diaphragm/electrolyte material. Li-B alloy is used as a positive electrode material, FeS2 is used as a battery negative electrode material, a diaphragm/electrolyte material is used for assembling a thermal battery, the assembled thermal battery is connected with a computer-controlled test system, the battery is rapidly activated under control, and the pulse discharge performance of a single battery adopting the ceramic fiber diaphragm is researched. The results are shown in FIG. 3.

As can be seen from fig. 3, at the same quantitative level, the separator using ceramic fibers having a diameter of 2 to 3 μm is thinner, and lithium ion transport is faster and pulse discharge performance is better when a considerable amount of electrolyte is loaded.