Novel thermal battery electrolyte as well as preparation method and application thereof

Abstract

The invention relates to the technical field of thermal batteries, in particular to a novel thermal battery electrolyte as well as a preparation method and application thereof. According to the invention, the nano gamma-Al2O3 is introduced, and the ratio of the raw materials in the electrolyte is optimized, namely 30%-60% of the nano gamma-Al2O3 and 40%-70% of the fused salt; the prepared electrolyte has good affinity and relatively low internal resistance; and the electrical conductivity and the working holding time of the electrolyte are obviously superior to those of a fused salt / MgO electrolyte in the prior art. According to the preparation method disclosed by the invention, the mixture is firstly subjected to vacuum drying, and the molten salt and the nano gamma-Al2O3 are relatively high in moisture absorption, so that moisture in the molten salt and the nano gamma-Al2O3 can be removed, and the molten salt and the nano gamma-Al2O3 can be dispersed more uniformly during ball-milling and mixing as the molten salt and the nano gamma-Al2O3 are dried by adopting vacuum drying.

Description

Technical Field

[0001] The invention relates to the technical field of thermal batteries, in particular to a novel thermal battery electrolyte 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 monomers are mainly composed of current collectors, positive plates, diaphragm plates, negative plates, heating plates, etc., and a unit thermal battery is composed of multiple thermal battery monomers. 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 between 400℃ and 600℃. It uses high-temperature molten salt as the electrolyte. The electrolyte is a low-melting melt 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 is needed to work, the thermal battery is activated, and the non-conductive solid electrolyte at room temperature quickly melts into a molten ion conductor, and the battery begins to discharge. After working for a period of time, as the internal heating plate of the battery is consumed and heat is lost, the operating temperature of the thermal battery begins to drop, and finally the electrolyte changes from a molten state to a solid state, and the battery stops discharging. Therefore, under certain internal heat conditions of the thermal battery, the smaller the internal resistance, the smaller the internal power consumption, and the longer the normal operation of the thermal battery can be maintained.

[0004] At present, thermal battery electrolytes need to add flow inhibitors such as MgO and SiO2 to prevent leakage and short circuit after heating and melting. The optimization of parameters such as the type, morphology, specific surface area and usage ratio of the flow inhibitor can increase the affinity between the molten salt and the electrolyte to reduce the internal resistance of the battery, thereby improving the electrochemical performance of the thermal battery and improving the safety and reliability of the battery. This is the current key research direction. Summary of the invention

[0005] In order to solve the above technical problems existing in the prior art, the present invention provides a new thermal battery electrolyte and a preparation method and application thereof, which are specifically achieved through the following technical solutions.

[0006] A new type of thermal battery electrolyte, the raw materials and their mass percentages are: nano γ-Al2O3 30% to 60%, molten salt 40% to 70%. This ratio makes the prepared electrolyte have good affinity and low internal resistance; its conductivity and working retention time are significantly better than the molten salt / MgO electrolyte in the prior art.

[0007] Furthermore, the specific surface area of ​​the nano-γ-Al2O3 is 150m 2 / g~200m 2 / g. Nano-γ-Al2O3 has good high temperature resistance and specific surface area, and has good affinity with high temperature molten salt; it can effectively absorb more high temperature molten salt, and does not react with molten salt, which can significantly improve the conductivity and internal resistance of the electrolyte.

[0008] Furthermore, the particle size of the nano-γ-Al2O3 is 20nm to 100nm. Using nano-γ-Al2O3 in this range can effectively disperse the nano-γ-Al2O3 in the molten salt, ensure the bulkiness of the electrolyte, and ensure that the electrolyte has good conductivity and low internal resistance while ensuring the overall compaction density of the electrolyte.

[0009] Furthermore, the molten salt is a binary halide molten salt (which may be composed of lithium chloride and potassium chloride) or a ternary halide molten salt (which may be composed of lithium chloride, lithium bromide and lithium fluoride).

[0010] The preparation method of the novel thermal battery electrolyte specifically comprises the following steps:

[0011] Step 1, weighing molten salt and nano-γ-Al2O3 respectively according to mass percentage, and then vacuum drying them for standby use;

[0012] Step 2: ball-milling the molten salt and nano-γ-Al2O3 to obtain a mixture, and then putting it into a high-temperature furnace for melting;

[0013] Step 3: Cool the molten mixture, and then crush it through a standard sieve of 80-200 meshes to obtain a new thermal battery electrolyte.

[0014] Furthermore, in step 2, the diameter of the ball milling beads in the ball mill is 10 mm to 50 mm; the speed of the ball mill is 10 r / min to 200 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 mixed material and enhancing the coating effect of the nano-γ-Al2O3 by the molten salt, which helps to fully mix the molten salt and the nano-γ-Al2O3.

[0015] Furthermore, in step 2, the temperature in the high temperature furnace is 300° C. to 600° C., and the melting time is 4 hours to 12 hours. This method can ensure that the molten salt fully infiltrates the nano-γ-Al2O3 and is adsorbed.

[0016] Furthermore, in step 3, the cooling temperature in the ball mill is 10° C. to 40° C., the cooling time is 4 hours to 8 hours, and the humidity is 1% to 8%. The cooling with a humidity of 1% to 5% ensures that the electrolyte is not damp while ensuring stability and consistency.

[0017] Application of the novel thermal battery electrolyte in thermal batteries.

[0018] Furthermore, in the thermal battery, the novel thermal battery electrolyte is made into a diaphragm sheet and applied to the thermal battery.

[0019] After the electrolyte in the present application is made into a diaphragm sheet and applied to a thermal battery, it can significantly reduce the internal resistance and delay the solidification time of the thermal battery, enhance the thermal battery's ability to resist large current pulses and continuous power output, and extend the battery's power supply time, thereby improving the electrical performance of the thermal battery.

[0020] Compared with the prior art, the technical effects created by the present invention are embodied in:

[0021] (1) The present application introduces nano-γ-Al2O3 and optimizes the ratio of each raw material in the electrolyte, namely, 30% to 60% of nano-γ-Al2O3 and 40% to 70% of molten salt; the prepared electrolyte has good affinity and low internal resistance; its conductivity and working retention time are significantly better than those of the molten salt / MgO electrolyte in the prior art.

[0022] (2) The present application first performs vacuum drying on the mixture. Since the molten salt and nano-γ-Al2O3 have high hygroscopicity, vacuum drying can be used to remove moisture from the molten salt and nano-γ-Al2O3, and can also disperse the molten salt and nano-γ-Al2O3 more evenly during ball milling.

[0023] (3) The nano-γ-Al2O3 in the electrolyte of this application has a high specific surface area (γ-Al2O3 is 150 m 2 / g~200m 2 / g,MgO≤40m 2 / g), wettability and thermal stability (melting point>2100℃), can be used as a flow inhibitor to compound with high-temperature molten salt to prepare a thermal battery electrolyte with good affinity and low internal resistance. Therefore, it can be widely used in thermal batteries that require long-term power supply and high current. After the electrolyte in this application is made into a diaphragm sheet and applied to a thermal battery, it can significantly reduce the internal resistance of the thermal battery and delay the solidification time, enhance the thermal battery's ability to resist large current pulses and continuous power output, and extend the battery power supply time, thereby improving the electrical performance of the thermal battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 1 is a comparison chart of discharge curves of the electrolyte in Example 1 and the electrolyte in the prior art after being applied to a thermal battery. DETAILED DESCRIPTION

[0025] 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.

[0026] Example 1

[0027] Step 1: Weigh molten salt and nano-γ-Al2O3 (specific surface area 180m2) in a mass percentage of molten salt: nano-γ-Al2O3 = 55:45. 2 / g, particle size 30nm), and then vacuum dried for use; the specific ratio of the molten salt used is as follows: lithium chloride: lithium bromide: lithium fluoride = (20-23): (66-69): (8-10).

[0028] Step 2: ball mill the molten salt and nano-γ-Al2O3 for 1 h at a bead diameter of 35 mm and a rotation speed of 50 r / min to obtain a mixture, and then melt the mixture at 400°C for 6 h;

[0029] Step 3: Cool the molten mixture in an environment with a humidity of 2% and a temperature of 25° C. for 6 hours, and crush it through a 100-grit sieve to obtain a new thermal battery electrolyte.

[0030] Example 2

[0031] Step 1: Weigh molten salt and nano-γ-Al2O3 (specific surface area 180m2) in a mass percentage of molten salt: nano-γ-Al2O3 = 55:45. 2 / g, particle size 30nm), and then vacuum dried for use; the specific ratio of the molten salt used is as follows: lithium chloride: potassium chloride = (40-48): (52-60).

[0032] Step 2: ball mill the molten salt and nano-γ-Al2O3 for 1 h at a bead diameter of 35 mm and a rotation speed of 50 r / min to obtain a mixture, and then melt the mixture at 400°C for 6 h;

[0033] Step 3: Cool the molten mixture in an environment with a humidity of 2% and a temperature of 25° C. for 6 hours, and crush it through a 100-grit sieve to obtain a new thermal battery electrolyte.

[0034] The thermal battery monomer is mainly composed of a current collector, a positive electrode, a diaphragm, a negative electrode, a heating plate, etc. The thermal battery is composed of multiple thermal battery monomers, and the diaphragm is made of a thermal battery electrolyte. The new thermal battery electrolyte obtained in Example 1 is made into a diaphragm, and then made into a thermal battery monomer with a current collector, a positive electrode, a negative electrode, a heating plate, etc. to form a thermal battery.

[0035] 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 novel thermal battery electrolyte, characterized in that: The raw materials and their mass percentages are: 30% to 60% of nanometer gamma-Al2O3 and 40% to 70% of molten salt.

2. The novel thermal battery electrolyte according to claim 1, characterized in that: The specific surface area of ​​the nano-γ-Al2O3 is 150m 2 / g~200m 2 / g.

3. The novel thermal battery electrolyte according to claim 1, characterized in that: The particle size of the nano-γ-Al2O3 is 20nm-100nm.

4. The novel thermal battery electrolyte according to claim 1, characterized in that: The molten salt is a binary halide molten salt or a ternary halide molten salt.

5. The method for preparing the novel thermal battery electrolyte according to claim 1, characterized in that: The specific steps include: Step 1, weighing molten salt and nano-γ-Al2O3 respectively according to mass percentage, and then vacuum drying them for standby use; Step 2: ball-milling the molten salt and nano-γ-Al2O3 to obtain a mixture, and then putting it into a high-temperature furnace for melting; Step 3: Cool the molten mixture, and then crush it through a standard sieve of 80-200 meshes to obtain a new thermal battery electrolyte.

6. The method for preparing the novel thermal battery electrolyte according to claim 5, characterized in that: In the step 2, the diameter of the ball milling beads in the ball mill is 10 mm to 50 mm; the rotation speed of the ball mill is 10 r / min to 200 r / min, and the ball milling time is 0.5 h to 2 h.

7. The method for preparing the novel thermal battery electrolyte according to claim 1, characterized in that: In the step 2, the temperature in the high temperature furnace is 300° C. to 600° C., and the melting time is 4 h to 12 h.

8. The method for preparing the novel thermal battery electrolyte according to claim 1, characterized in that: In the step 3, the cooling temperature in the ball mill is 10° C. to 40° C., the time is 4 h to 8 h, and the humidity is 1% to 8%.

9. Application of the novel thermal battery electrolyte according to claim 1 in thermal batteries.

10. The use according to claim 9, characterized in that: In the thermal battery, the novel thermal battery electrolyte is made into a diaphragm sheet and applied to the thermal battery.

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