High-conductivity slow-release heating powder as well as preparation method and application thereof

Abstract

The invention relates to the technical field of thermal batteries, in particular to high-conductivity slow-release heating powder and a preparation method and application thereof.The high-conductivity slow-release heating powder is prepared by introducing high-conductivity conductive graphite and slow-release inert powder and optimizing the raw material ratio in the high-conductivity slow-release heating powder, namely, 60%-80% of Fe powder, 15%-35% of KClO4 powder, 1%-5% of high-conductivity conductive graphite and 5%-15% of inert dispersed powder; the prepared high-conductivity slow-release heating powder has good conductivity and relatively slow heat release; and the conductivity and heat retention time of the Fe / KClO4 heating powder are obviously superior to those of Fe / KClO4 heating powder in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of thermal batteries, in particular to a high-conductivity slow-release heating powder and a preparation method and application thereof. Background Art

[0002] Thermal batteries, also known as primary molten salt batteries, have high specific energy, high specific power, high power discharge, long storage time, etc. These excellent features have very important uses in the field of military batteries and have rapidly developed into an ideal power source for modern weapons. Thermal battery cells are mainly composed of current collectors, positive plates, electrolytes, diaphragms, negative plates, heaters, etc., and a unit thermal battery is composed of multiple thermal battery cells. With the development of the mining industry and aerospace fields, thermal batteries have also been successfully applied to the above industries.

[0003] The operating temperature of the thermal battery is 400℃~600℃, and high temperature molten salt is used as the electrolyte. The electrolyte is a low eutectic composed of two or more inorganic salts. At room temperature, the inorganic salt is a solid with an internal resistance of tens of megohms, and the battery has almost no self-discharge. When the thermal battery needs to work, the electrolyte is melted by igniting the heating powder to provide a heat source. The rapidly melted electrolyte forms a high-conductivity ion conductor, thereby activating the thermal battery and starting the discharge work.

[0004] At present, the mainstream heating powder of thermal batteries is Fe+KClO4. The mixed Fe and KClO4 are pressed into a heating sheet, which has the advantages of fast heat generation, less gas generation, and less volume change. The mass ratio of Fe powder to KClO4 ranges from 80:20 to 88:12. According to reaction formula (1), the mass ratio of Fe and KClO4 for complete reaction is 26:16. The remaining iron powder acts as a conductive agent and becomes an electron transport channel between thermal battery cells.

[0005] 4Fe+KClO4→4FeO+KCl (1)

[0006] Under high temperature conditions, the conductivity of iron powder at 500℃ is 2.0×10 4 Sm -1 , conductive graphite is 6.5×10 5 Sm -1 At the same time, the burning rate of the oxidation-reduction reaction of Fe and KClO4 is (10-40) cm / s, which is fast, while lightweight MgO is an inert material with a large surface area and good dispersibility. As the requirements for thermal battery performance (longer working time, higher voltage, and greater current density) become more and more stringent, the heating powder is required to release heat slowly and have good conductivity. Fe / KClO4 heating powder is increasingly unable to meet the use of high-performance thermal batteries, so a heating powder with slow heat release and high conductivity is needed. Summary of the invention

[0007] In order to solve the above technical problems existing in the prior art, the present invention provides a high-conductivity sustained-release heating powder and a preparation method and application thereof, which are specifically achieved through the following technical solutions.

[0008] A high-conductivity slow-release heating powder comprises the following raw materials: Fe powder, KClO4 powder, high-conductivity conductive graphite, and inert dispersion powder; wherein the mass percentages of Fe powder and KClO4 powder are as follows: 60% to 80% of Fe powder, and 15% to 35% of KClO4 powder. This ratio enables the prepared high-conductivity slow-release heating powder to have good conductivity and slow heat release; its conductivity and heat retention time are significantly better than those of Fe / KClO4 heating powder in the prior art.

[0009] Furthermore, the high-conductivity graphite powder is a mixture of one or more of graphite powder, conductive graphite powder, and carbon nanotube powder in any proportion. Graphite powder, conductive graphite powder, and carbon nanotube powder have good high-temperature conductivity and do not react with KClO4; they can significantly improve the conductivity of the heating powder.

[0010] Furthermore, the mass percentage of the high-conductivity conductive graphite is 1% to 5%. The use of high-conductivity conductive graphite in this range ensures that the overall performance of the heating powder is ensured while ensuring that the high-conductivity conductive graphite has good conductivity.

[0011] Furthermore, the inert dispersion powder is one or both of MgO powder and Al2O3 powder mixed in any proportion. MgO powder and / or Al2O3 powder have large surface areas, can effectively disperse Fe powder and KClO4 powder, delay the burning rate of Fe and KClO4 oxidation-reduction reaction, and do not react with KClO4, which can significantly improve the heat release of the heating powder.

[0012] Furthermore, the mass percentage of the inert dispersible powder is 5% to 15%. The use of inert dispersible powder within this range ensures the overall performance of the heating powder while ensuring that the inert dispersible powder has good dispersibility and a moderate heat release rate.

[0013] The method for preparing the high-conductivity sustained-release heating powder is characterized in that it specifically comprises the following steps:

[0014] (1) Weighing Fe powder, KClO4 powder, and high-conductivity conductive graphite respectively according to mass percentage, and then drying them for later use;

[0015] (2) Fe powder, high-conductivity conductive graphite and KClO4 powder are mixed to obtain a mixture, and then put into a ball mill for ball milling;

[0016] (3) Add inert dispersing powder to the ball-milled mixture and mix them evenly. After mixing, the mixture is ball-milled and then passed through a 100-200 mesh standard sieve to obtain a high-conductivity slow-release heating powder.

[0017] In this scheme, the mixture is first ball-milled. Since the hardness of the mixture is relatively large, a higher speed is used to ball-mill it, which can evenly mix Fe powder, KClO4 powder and high-conductivity conductive graphite, and can also grind Fe powder, KClO4 powder and high-conductivity conductive graphite finer. After the mixture is ball-milled, inert dispersion powder is added for ball-milling, so that the mixed heating powder can be evenly dispersed.

[0018] Furthermore, the method for preparing the high-conductivity slow-release heating powder is characterized in that, in step (2), the diameter of the ball milling beads in the ball mill is 10 mm to 20 mm; the speed of the ball mill is 500 r / min to 2000 r / min, and the ball milling time is 0.5 h to 2 h. This method improves the ball milling efficiency while reducing the particle size of the mixture, which helps to fully mix the Fe powder, KClO4 powder and high-conductivity conductive graphite.

[0019] Furthermore, the method for preparing the high-conductivity sustained-release heating powder is characterized in that, in the step 3, the diameter of the ball milling beads in the ball mill is 25 mm to 40 mm; the rotation speed of the ball mill is 25 r / min to 40 r / min, and the ball milling time is 0.5 h to 4 h. The ball milling at 25 r / min to 40 r / min ensures the ball milling efficiency while ensuring uniform mixing and dispersion.

[0020] The application of the high-conductivity slow-release heating powder in thermal batteries is specifically to reduce the internal resistance of thermal batteries, delay heat release, enhance the thermal battery's ability to resist large current pulses and high voltage output, extend the battery power supply time, and improve the electrical performance of thermal batteries.

[0021] Compared with the prior art, the technical effects created by the present invention are embodied in:

[0022] (1) The present invention introduces high-conductivity conductive graphite and slow-release inert powder, and optimizes the ratio of each raw material in the high-conductivity slow-release heating powder, namely 60% to 80% of Fe powder, 15% to 35% of KClO4 powder, 1% to 5% of high-conductivity conductive graphite and 5% to 15% of inert dispersed powder; so that the prepared high-conductivity slow-release heating powder has good conductivity and slower heat release; its conductivity and heat retention time are significantly better than those of the Fe / KClO4 heating powder in the prior art.

[0023] (2) In the present invention, the mixed material is first ball-milled during preparation. Since the mixed material has a large hardness, it is ball-milled at a high speed, so that the Fe powder, KClO4 powder and high-conductivity conductive graphite can be evenly mixed, and the Fe powder, KClO4 powder and high-conductivity conductive graphite can be ground finer. After the mixed material is ball-milled, an inert dispersion powder is added and ball-milled, so that the mixed heating powder can be evenly dispersed.

[0024] (3) Since the high-conductivity slow-release heating powder in the present invention has good conductivity and slow heat release, it can be widely used in thermal batteries that require long-term power supply, high current, and high voltage. After the high-conductivity slow-release heating powder in this application is made into a high-conductivity slow-release heating sheet and applied to the thermal battery, it can significantly reduce the internal resistance of the thermal battery and delay the heat release, enhance the thermal battery's ability to resist large current pulses and high voltage output, and extend the battery power supply time, thereby improving the electrical performance of the thermal battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a comparison chart of discharge curves of the high-conductivity slow-release heating powder in Example 1 (Fe powder: KClO4 powder: high-conductivity conductive graphite = 80:15:1, ball milled for 1 hour at a grinding bead diameter of 15 mm and a rotation speed of 1000 r / min; then adding 4% MgO powder and grinding beads with a diameter of 30 mm, and ball milling for 2 hours at a rotation speed of 1000 r / min) and the heating powder in the prior art after being applied to a thermal battery. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further defined below in conjunction with specific implementation methods, but the scope of protection required is not limited to the description.

[0027] Example 1

[0028] Preparation of high conductivity sustained-release heating powder:

[0029] (1) Weigh 800 g of Fe powder, 150 g of KClO4 powder, and 10 g of high-conductivity conductive graphite respectively, and then dry them for later use;

[0030] (2) Fe powder, high-conductivity conductive graphite and KClO4 powder are mixed to obtain a mixture, and then put into a ball mill for ball milling at a bead diameter of 15 mm and a rotation speed of 1000 r / min for 1 h;

[0031] (3) Add 4% MgO powder and grinding beads with a diameter of 30 mm to the ball-milled mixture, ball-mill for 2 h at a rotation speed of 1000 r / min, and then pass through a standard sieve of 100-200 meshes to obtain a high-conductivity slow-release heating powder.

[0032] Comparative experiment:

[0033] The discharge curve comparison diagram of the high conductivity slow-release heating powder obtained in Example 1 and the heating powder in the prior art after being applied to the thermal battery is shown in FIG. Figure 1 .

[0034] Finally, it should be pointed out that the above embodiments are only representative examples of the present invention. Obviously, the technical solution of the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by ordinary technicians in this field should be considered as the protection scope of the present invention.

Claims

1. A high conductivity sustained-release heating powder, characterized in that: The invention comprises the following raw materials: Fe powder, KClO4 powder, high-conductivity conductive graphite and inert dispersion powder; wherein the mass percentages of Fe powder and KClO4 powder are as follows: 60% to 80% of Fe powder and 15% to 35% of KClO4 powder.

2. The high-conductivity sustained-release heating powder according to claim 1, characterized in that: The high-conductivity graphite powder is a mixture of one or more of graphite powder, conductive graphite powder and carbon nanotube powder in any proportion.

3. The high-conductivity sustained-release heating powder according to claim 1, characterized in that: The mass percentage of the high-conductivity conductive graphite is 1% to 5%.

4. The high-conductivity sustained-release heating powder according to claim 1, characterized in that: The inert dispersed powder is one of MgO powder and Al2O3 powder or a mixture of the two in any proportion.

5. The high-conductivity sustained-release heating powder according to claim 1, characterized in that: The mass percentage of the inert dispersible powder is 5% to 15%.

6. The method for preparing the high-conductivity sustained-release heating powder according to claim 1, characterized in that: The specific steps include: (1) Weighing Fe powder, KClO4 powder, and high-conductivity conductive graphite respectively according to mass percentage, and then drying them for later use; (2) mixing Fe powder, high-conductivity conductive graphite and KClO4 powder to obtain a mixture, and then placing the mixture in a ball mill for ball milling; (3) Add inert dispersing powder to the ball-milled mixture and mix them evenly. After mixing, the mixture is ball-milled and then passed through a 100-200 mesh standard sieve to obtain a high-conductivity slow-release heating powder.

7. The method for preparing the high-conductivity sustained-release heating powder according to claim 6, characterized in that: In step (2), the diameter of the ball milling beads in the ball mill is 10 mm to 20 mm; the rotation speed of the ball mill is 500 r / min to 2000 r / min, and the ball milling time is 0.5 h to 2 h.

8. The method for preparing the high-conductivity sustained-release heating powder according to claim 6, characterized in that: In the step 3, the diameter of the ball milling beads in the ball mill is 25 mm to 40 mm; the rotation speed of the ball mill is 25 r / min to 40 r / min, and the ball milling time is 0.5 h to 4 h.

9. Application of the high-conductivity slow-release heating powder according to claim 1 in thermal batteries.

10. The use according to claim 9, characterized in that: The thermal battery is used to reduce the internal resistance of the thermal battery, delay heat release, enhance the thermal battery's ability to resist large current pulses and high voltage output, extend the battery's power supply time, and improve the thermal battery's electrical performance.

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