High-safety temperature control assembly for thermal battery and preparation method thereof

Abstract

The application discloses a high-safety temperature control assembly for thermal batteries and a preparation method thereof, and belongs to the technical field of thermal batteries. The temperature control assembly comprises a closed cavity formed by welding a first shell and a second shell, and a powdery inorganic salt phase change material sealed in the cavity. The shell is made of an insulating ceramic material with a thermal conductivity of 80-200 W / (m*K), an electrical resistivity greater than 1015 ohm*cm and a melting point higher than 1200 DEG C, thereby realizing 360-degree omnibearing physical isolation and coating of the phase change material. The overall leakage rate of the assembly is not greater than 3*10 ‑5 Pa*m 3 / s. The application realizes efficient heat storage and release through the high-thermal-conductivity shell, balances the temperature of the battery stack, and completely eliminates the overflow problem of the molten phase change material under high temperature and mechanical conditions through the fully-closed structure and strict leakage rate control, thereby eliminating the insulation failure and short circuit hidden danger caused by the overflow, and significantly improving the safety of the thermal battery.

Description

Technical Field

[0001] This invention relates to the field of thermal battery technology, specifically to a high-safety temperature control component for thermal batteries and its preparation method. Background Technology

[0002] A thermal battery is a type of storage battery that uses molten salt as the electrolyte. It ignites an internal ignition source through electrical or mechanical activation, heating the solid electrolyte to a molten state. Electrical energy is then generated at the positive and negative electrodes through an electrolyte reaction. Due to the high conductivity of molten salt electrolytes, thermal batteries offer significant advantages, including high current discharge capability, high specific energy and power, wide operating temperature range, long storage time, rapid and reliable activation, strong resistance to mechanical environments, and maintenance-free operation.

[0003] As application scenarios continue to expand, higher demands are being placed on the energy density and operating time of thermal batteries. To maintain longer operation, a larger heating capacity is required, leading to a significant increase in internal battery temperature and highlighting the problem of uneven heat distribution within the battery stack. To balance temperature and absorb excess heat, existing technologies typically employ a ring-shaped temperature control component made of insulating material, filled with phase change material and placed radially outside the battery stack for confinement. However, this structure only provides limited radial confinement and cannot achieve 360° full coverage. During operation, the phase change material heats up and becomes a molten salt. Since thermal batteries are subjected to mechanical conditions such as impact, vibration, and acceleration during application, the molten phase change material can easily overflow from the limited confinement, covering adjacent cells or internal structural components, causing insulation failure and triggering serious safety issues such as battery short circuits.

[0004] Another existing technical document, JPH06223844A, discloses a method for airtightening a thermal battery casing. This method involves cutting threads on the side of the battery cover, screwing them into the battery casing, and installing a silicone rubber gasket or sealing material to achieve an airtight seal. The purpose is to prevent welding heat from damaging the airtight glass and to facilitate disassembly. However, this solution aims to address the overall sealing and reusability of the battery casing, but does not address the encapsulation of phase change materials within the internal temperature control components. Furthermore, the silicone rubber and other sealing materials used have limited temperature resistance and cannot provide a reliable full-coverage seal for molten salts under long-term high temperatures and strong mechanical conditions inside the thermal battery, nor can they meet the requirements for high thermal conductivity and strong insulation. Therefore, this solution cannot solve the safety problems caused by phase change material overflow.

[0005] In summary, there is an urgent need for breakthroughs in existing technologies. A high-safety temperature control component is required that can achieve 360° absolute safety confinement of phase change materials under high temperature and full-power operating conditions, while also possessing efficient thermal management capabilities. Summary of the Invention

[0006] The purpose of this invention is to provide a high-safety temperature control component for thermal batteries and its preparation method, so as to solve the defects in the prior art where phase change materials cannot achieve 360° full coverage and restraint under high temperature and mechanical conditions (impact, vibration, acceleration), resulting in overflow, which leads to internal insulation failure, short circuit and other safety problems in the battery.

[0007] The technical solution of the present invention: A high-safety temperature control component for a thermal battery includes a shell, which is a closed cavity formed by welding a first shell and a second shell together; the shell is made of an insulating ceramic material with a thermal conductivity of 80-200 W / (m·K), a resistivity greater than 1015 Ω·cm, and a melting point higher than 1200℃, so as to achieve 360° all-round physical isolation and encapsulation of the phase change material contained therein; The phase change material is a powdered phase change molten salt prepared from mono- or multi-component inorganic salts, which is sealed in the closed cavity of the outer shell; The leakage rate of the sealed cavity is no greater than 3×10⁻⁶. -5 Pa·m 3 / s, to prevent the molten phase change material from overflowing from the shell under mechanical conditions.

[0008] Furthermore, the insulating ceramic material is a composite material composed of one or more of beryllium oxide, aluminum oxide, aluminum nitride, boron nitride, or silicon nitride.

[0009] Furthermore, the temperature control component is in the shape of a circular disc.

[0010] Furthermore, the size of the circular disc can be set to any size according to the requirements of the thermal battery.

[0011] Furthermore, the welding method is one of brazing, diffusion welding, or laser welding.

[0012] A method for preparing a high-safety temperature control component for a thermal battery involves, in a dry environment with humidity less than 3%, spreading a phase change material ground into powder into the inner cavity of a first outer shell; covering the first outer shell with a second outer shell; and, under an inert gas protective environment, connecting and sealing the first and second outer shells by welding to form a seal with a leakage rate not exceeding 3 × 10⁻⁶. -5 Pa·m 3 / s closed cavity.

[0013] Furthermore, the powder of the phase change material is 80 mesh.

[0014] The beneficial effects of this invention are as follows: The high-safety temperature control component for thermal batteries of this invention uses a shell made of highly thermally conductive, corrosion-resistant, and strongly insulating materials to completely encapsulate the phase change material (PCM) at 360°, preventing overflow after the PCM melts at high temperatures. The PCM efficiently stores or dissipates heat through the high thermal conductivity of the shell, effectively ensuring effective heat control within the thermal battery. Simultaneously, the shell material is an insulator and can be placed anywhere inside the thermal battery without affecting the insulation requirements during battery operation, allowing for on-demand arrangement within the thermal battery. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a front view of the high-safety temperature control component of the present invention; Figure 2 This is a top view of the high-safety temperature control component of the present invention; Reference numerals: 1-Second outer shell; 2-Phase change material; 3-First outer shell. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0018] The technical problem this invention aims to solve is that under high-capacity, long-term operating conditions, due to high thermal design and mechanical factors, the phase change material used may overflow after melting. This overflow can lead to a short circuit in the battery, causing safety issues. This invention provides a high-safety temperature control component for thermal batteries and its preparation method, solving the problem of effectively confining the phase change material 360° under high-heat, high-mechanical operating conditions to achieve absolute safety. Simultaneously, it enables the component to be stored and transported at room temperature, reducing the difficulty of production preparation.

[0019] Reference Figure 1 and Figure 2A high-safety temperature control component for a thermal battery includes a shell and a phase change material (PCM). The shell is resistant to high-temperature impact, corrosion, has high thermal conductivity, and strong insulation; it is a sealed cavity. The PCM is 360° enclosed by the shell to prevent overflow after melting at high temperatures. The PCM can efficiently store or dissipate heat through the high thermal conductivity of the shell, effectively ensuring effective heat control inside the thermal battery. Simultaneously, the shell material is an insulator and can be placed anywhere inside the thermal battery without affecting the insulation requirements during battery operation, allowing for customized internal arrangement within the thermal battery.

[0020] The outer shell is a cavity structure formed by welding or other methods to create a first outer shell 1 and a second outer shell 3. The high-safety temperature control component for the thermal battery is prepared by spreading phase change material 2 powder into the inner cavity of the first outer shell 1 in a dry environment with humidity less than 3%, then covering it with the second outer shell 3, and finally sealing the first outer shell 1 and the second outer shell 3 by welding in an inert gas environment to form a sealed body. The outer shell material is a composite material composed of one or more of beryllium oxide, aluminum oxide, aluminum nitride, boron nitride, or silicon nitride, with a thermal conductivity of 80–200 W / (m·K), a resistivity greater than 10¹⁵ Ω·cm, and a melting point above 1200℃. Welding methods include brazing, diffusion welding, and laser welding. The outer shell physically isolates the phase change material from the external environment, achieving effective 360° all-around coverage, and the leakage rate of the temperature control component is required to be no greater than 3×10-5 Pa·m. 3 The temperature control component is circular and disc-shaped, and its size can be customized to meet the needs of the thermal battery. The phase change material can be prepared from mono- or multi-element phase change molten salts, requiring an ambient humidity of less than 3% and grinding to an 80-mesh powder state.

[0021] Example 1: High-Safety Temperature Control Component for Thermal Batteries. This example provides a high-safety temperature control component for thermal batteries, the structure of which is as follows: Figure 1 and Figure 2 As shown, the temperature control component consists of a first outer shell 3, a second outer shell 1, and a phase change material 2. The first outer shell 3 is a shell with an inner cavity, in which the phase change material 2 is evenly spread; the second outer shell 1 is a cover plate that covers the first outer shell 3. The first outer shell 3 and the second outer shell 1 are connected by laser welding to form a complete closed cavity, achieving 360° all-round physical isolation and coverage of the internal phase change material 2.

[0022] Casing Material: Both the first casing 3 and the second casing 1 are made of aluminum nitride ceramic material. This material has excellent comprehensive properties: a thermal conductivity of 180 W / (m·K), enabling efficient heat conduction; and a resistivity of 10⁻⁶ W / (m·K). 16Ω·cm is an excellent insulator; its melting point is as high as 2200℃, far exceeding the operating temperature range of thermal batteries, ensuring that the structure remains intact under extreme conditions.

[0023] Phase change material: The phase change molten salt is prepared by mixing multiple inorganic salts such as lithium chloride and potassium chloride in a eutectic ratio and pre-grinding it into 80-mesh powder.

[0024] When the thermal battery is operating, a large amount of heat is generated inside the battery stack, causing the temperature to rise rapidly. In this embodiment, the temperature control component uses a highly thermally conductive aluminum nitride shell to quickly transfer the excess heat generated in the early stages of operation to the internal phase change material powder. The phase change material absorbs the heat and undergoes a phase change melting, storing the heat as latent heat, thereby suppressing the rapid rise in battery stack temperature. When the temperature begins to decrease in the later stages of thermal battery operation, the molten phase change material releases the stored heat through the shell, maintaining a stable battery stack temperature and achieving effective heat balance over time.

[0025] Meanwhile, when the thermal battery is subjected to mechanical conditions such as impact, vibration, and acceleration, the molten phase change material is completely bound by the closed cavity formed by the aluminum nitride shell, and the overall size of the component is no greater than 3×10. -5 Pa·m 3 With a leakage rate of / s, this eliminates any possibility of molten salt overflow, completely eradicating the safety hazard of insulation failure between adjacent cells or structural components due to molten salt leakage, which could lead to battery short circuits. Furthermore, because the casing itself is made of highly insulating material, this component can be flexibly placed anywhere within the battery stack according to thermal management needs, without affecting the battery's insulation layout.

[0026] Example 2: This example provides a method for preparing the above-mentioned high-safety temperature control component for a thermal battery, including the following steps: Step 1: Environmental Preparation and Material Pretreatment. All operations are carried out in a dry room where the ambient humidity is strictly controlled to be less than 3%. The multi-element inorganic salt phase change material prepared in the specified proportion is ground to achieve an 80-mesh powder state to ensure uniform powder particle size, which is conducive to uniform spreading and heat conduction.

[0027] Step 2: Phase change material filling. Take the first outer shell 3 and place it with its inner cavity facing upwards. Evenly spread the prepared 80-mesh phase change material powder into the inner cavity of the first outer shell 3. The filling amount is calculated and determined according to the specific thermal management requirements of the thermal battery, and ensure that the powder surface is flat.

[0028] Step 3: Closing the outer shell. Accurately cover the first outer shell 3 with the second outer shell 1, ensuring that the mating surfaces of the two are tightly fitted, thus completing the initial closure of the assembly.

[0029] Step 4: Welding and Sealing. The assembled assembly is moved into an inert gas chamber filled with high-purity argon. Under this inert gas protection environment, laser welding is used to weld the entire circumference of the joint between the first outer shell 3 and the second outer shell 1, ensuring a firm connection and forming a sealed cavity.

[0030] Step 5: Leakage Detection. After soldering, a helium mass spectrometer leak detector is used to detect the leakage rate of the component. The test results show that the leakage rate of the temperature control component is no greater than 3 × 10⁻⁶. -5 Pa·m 3 / s, meeting design requirements and ensuring that components can be stored and transported under natural conditions.

[0031] This preparation method effectively prevents the inorganic salt phase change material from absorbing moisture and deteriorating by filling it in a dry environment with humidity less than 3%, ensuring the stability of the material's performance. Laser welding under inert gas protection avoids adverse reactions such as oxidation during high-temperature welding, ensuring welding quality and the performance of the shell material. The entire process is clear, controllable, and can stably and reliably produce high-safety temperature control components that meet leakage rate requirements.

[0032] The above provides a detailed description of a high-safety temperature control component for thermal batteries and its preparation method. Specific examples have been used to illustrate the structure and working principle of the invention. The descriptions of the embodiments are merely for the purpose of helping to understand the method and core ideas of the invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A high-safety temperature control component for a thermal battery, characterized in that: Includes an outer shell, which is a closed cavity formed by welding a first outer shell and a second outer shell together; the outer shell is made of a material with a thermal conductivity of 80-200 W / (m·K) and a resistivity greater than 10. 15 Insulating ceramic materials with Ω·cm and melting point above 1200℃ are used to achieve 360° all-round physical isolation and encapsulation of the phase change materials contained therein; The phase change material is a powdered phase change molten salt prepared from mono- or multi-component inorganic salts, which is sealed in the closed cavity of the outer shell; The leakage rate of the sealed cavity is no greater than 3×10⁻⁶. -5 Pa·m 3 / s, to prevent molten phase change material from overflowing from the shell under mechanical conditions.

2. The high-safety temperature control component for thermal batteries according to claim 1, characterized in that: The insulating ceramic material is a composite material composed of one or more of beryllium oxide, aluminum oxide, aluminum nitride, boron nitride, or silicon nitride.

3. The high-safety temperature control component for thermal batteries according to claim 1, characterized in that: The temperature control component is in the shape of a round disc.

4. The high-safety temperature control component for thermal batteries according to claim 3, characterized in that: The size of the circular disc can be set to any size according to the requirements of the thermal battery.

5. The high-safety temperature control component for thermal batteries according to claim 1, characterized in that: The welding method is one of brazing, diffusion welding or laser welding.

6. A method for preparing a high-safety temperature control component for a thermal battery according to any one of claims 1-5, characterized in that: In a dry environment with humidity less than 3%, the phase change material, ground into powder, is evenly spread into the inner cavity of the first outer shell; the second outer shell is then placed on top of the first outer shell; under an inert gas protective environment, the first and second outer shells are connected and sealed by welding to form a leak rate of no more than 3 × 10⁻⁶. -5 Pa·m 3 / s closed cavity.

7. The method for a high-safety temperature control component for a thermal battery according to claim 6, characterized in that: The phase change material is in powder form with a mesh size of 80.

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