Thermal battery stack with height self-adjusting function

Abstract

The invention discloses a thermal battery stack with a height self-adjusting function. The thermal battery stack comprises an upper fixing plate, a plurality of single batteries and a lower fixing plate, n thermal bimetal sheets and at least one hard metal sheet are further included, and n is a positive integer; the n thermal bimetallic strips are arranged between the upper fixing plate and the lower fixing plate, and the hard metal sheets are adjacent to the thermal bimetallic strips. The invention provides a thermal battery electric pile structure with a height self-adjusting function, which can maintain stable electric pile pressure when a thermal battery works, and can solve the problem of electric pile relaxation caused by electrolyte state transition when a sheet type structure thermal battery electric pile works.

Description

Technical Field

[0001] The present application relates to the technical field of thermal batteries, and in particular to a thermal battery stack with a high degree of self-regulation function. Background Art

[0002] Thermal batteries are heat-activated batteries. They use molten salt as the electrolyte and are activated by melting it with a heat source. At room temperature, the electrolyte is a non-conductive solid. The battery detonates the ignition element through an electrical signal or a mechanical signal, and then ignites the heat source of the heating plate in the battery pack, causing the temperature in the battery pack to instantly rise above the melting point of the electrolyte. The electrolyte melts into a high-conductivity ion conductor, activating the thermal battery. Thermal batteries have the advantages of small internal resistance, high specific energy and specific power, wide operating temperature range, long storage time, rapid and reliable activation, compact structure, no directionality during use and not affected by the installation orientation, can withstand harsh mechanical environments, and do not require maintenance. They are favored by the military and have become an ideal power source for modern weapons such as missiles, nuclear weapons, and artillery, occupying an important position in the military field. In recent years, due to their fast activation and maintenance-free characteristics, thermal batteries have also been gradually used in life-saving equipment, aircraft backup power supplies and other fields.

[0003] When a thermal battery is working, the electrolyte changes from a solid state to a molten state. During this process, the volume of the electrolyte layer will shrink by about 10-15%, causing the fastening pressure of the thermal battery stack to decrease, the stack to relax, and the contact impedance between single cells to increase, ultimately leading to a decrease in battery performance. There is currently no effective solution to this problem. Summary of the invention

[0004] The present application provides a thermal battery stack structure with a high degree of self-regulation function, the purpose of which is to solve the problem of stack relaxation caused by the change of electrolyte state when the sheet-type thermal battery stack is working. The thermal battery stack structure provided by the present invention can maintain the stability of the stack pressure when the thermal battery is working.

[0005] In a first aspect, a thermal battery stack with a highly self-regulating function is provided, comprising an upper fixed plate, a plurality of single cells, and a lower fixed plate; further comprising n thermal bimetallic sheets and at least one hard metal sheet, where n is a positive integer; the n thermal bimetallic sheets are arranged between the upper fixed plate and the lower fixed plate, and the hard metal sheet is arranged adjacent to the thermal bimetallic sheet.

[0006] In combination with the first aspect, in certain implementations of the first aspect, before and after the thermal battery is activated, the n thermal bimetallic strips satisfy:

[0007]

[0008] h is the thickness of a single thermal bimetallic strip, k is the thermal curvature of the thermal bimetallic strip, ΔT2 is the temperature change before and after the thermal battery is activated, d is the diameter of the thermal bimetallic strip, t is the thermal shrinkage of the single battery before and after activation, n0 is the number of single batteries, and D1 is the preset threshold value of the total deformation of the thermal battery stack before and after activation.

[0009] In combination with the first aspect, in certain implementations of the first aspect, in a high temperature storage state of the thermal battery, n thermal bimetallic strips satisfy:

[0010]

[0011] h is the thickness of a single thermal bimetal strip, k is the thermal curvature of the thermal bimetal strip, ΔT1 is the temperature change under high-temperature storage conditions, d is the diameter of the thermal bimetal strip, and D1 is the preset threshold value for the total deformation of n thermal bimetal strips under high-temperature storage conditions.

[0012] In combination with the first aspect, in certain implementations of the first aspect, the installation of the thermal bimetallic strip satisfies any of the following:

[0013] The single cell closest to the upper fixing plate among the single cells is a first single cell, the thermal bimetallic sheet is located between the upper fixing plate and the first single cell, and a hard metal sheet is sandwiched between the thermal bimetallic sheet and the first single cell;

[0014] The single cell closest to the lower fixing plate among the plurality of single cells is a second single cell, the thermal bimetallic sheet is located between the lower fixing plate and the second single cell, and a hard metal sheet is sandwiched between the thermal bimetallic sheet and the second single cell;

[0015] The thermal bimetallic strip is located between the third single cell and the fourth single cell, which are two adjacent single cells; a hard metal sheet is sandwiched between the thermal bimetallic strip and the third single cell, and a hard metal sheet is also sandwiched between the thermal bimetallic strip and the fourth single cell.

[0016] In combination with the first aspect, in certain implementations of the first aspect, a groove is opened in the center of the upper fixing plate or the lower fixing plate, and the thermal bimetallic strip is embedded in the groove.

[0017] In combination with the first aspect, in certain implementations of the first aspect, the depth of the groove is 0.5 mm to 4 mm, the diameter of the groove is 5 mm to 6 mm smaller than the diameter of the fixed plate where the groove is located, the diameter of the thermal bimetallic strip is the same as the diameter of the groove, and the total thickness of the n thermal bimetallic strips is equal to the depth of the groove.

[0018] In combination with the first aspect, in certain implementations of the first aspect, a diameter of the thermal bimetallic strip is the same as a diameter of the upper fixing plate or the lower fixing plate.

[0019] In combination with the first aspect, in certain implementations of the first aspect, a thickness of at least one of the upper fixing plate and the lower fixing plate is 3 mm to 5 mm.

[0020] In combination with the first aspect, in certain implementations of the first aspect, the operating temperature of the n thermo bimetallic strips is 300-600° C., and the total thickness of the n thermo bimetallic strips is 0.5 mm-4 mm.

[0021] In combination with the first aspect, in certain implementations of the first aspect, the diameter of the hard metal sheet is the same as the diameter of the upper fixed plate / lower fixed plate, the thickness of the hard metal sheet is 0.5mm~2mm, and the hard metal sheet is a stainless steel sheet or a titanium alloy sheet or a Fe-KClO4 heating sheet.

[0022] Compared with the prior art, the solution provided by this application includes at least the following beneficial technical effects:

[0023] The present invention aims at the problem that when the thermal battery is working, the electrolyte volume is reduced, resulting in stress relaxation of the battery stack, increased battery impedance and decreased performance. The present invention creatively proposes a thermal battery stack structure that can compensate for the height when the thermal battery is working. By utilizing the characteristic that the thermal bimetal deforms with temperature changes, the thermal battery stack maintains a constant height when working, avoiding the phenomenon of stack relaxation and battery performance degradation. The present invention provides a simple structure, simple design and assembly, low cost, strong applicability, and can be applied to thermal batteries of different sizes and usage requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of two types of battery stack structures with highly self-regulating functions.

[0025] Figure 2 Schematic diagram of the discharge curve comparison under the same conditions after the fuel cell stack with a high degree of self-regulation function in Example 1 and the conventional fuel cell stack are assembled into unit cells respectively, (a) is the comparison of the entire working voltage curve, (b) to (d) are the comparison of the voltage curves under 100A current pulses at 1100s, 1400s and 1700s respectively.

[0026] Figure numerals: 1 - upper fixing plate; 2 - single battery; 3 - hard metal sheet; 4 - lower fixing plate; 5 - thermal bimetallic sheet. DETAILED DESCRIPTION

[0027] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Figure 1Two types of thermal battery stacks with a height self-adjustment function provided by the present invention are shown. The thermal battery stack may include: an upper fixed plate 1, a plurality of single cells 2, a lower fixed plate 4 and other auxiliary structures and components necessary for the thermal battery stack. The upper fixed plate 1 and the lower fixed plate 4 are respectively installed at both ends of the stack. A plurality of single cells 2 are arranged between the upper fixed plate 1 and the lower fixed plate 4. The thermal battery stack may also include n thermal bimetallic strips 5 and at least one hard metal strip 3, where n is a positive integer. The n thermal bimetallic strips 5 are arranged between the upper fixed plate 1 and the lower fixed plate 4, and the hard metal strip 3 is arranged adjacent to the thermal bimetallic strip 5.

[0029] In some embodiments, the thermal bimetallic strip 5 can have the following three installation methods.

[0030] Installation method 1: the single cell closest to the upper fixed plate 1 among the single cells 2 is the first single cell, the thermal bimetallic strip 5 can be located between the upper fixed plate 1 and the first single cell, and a hard metal sheet 3 is sandwiched between the thermal bimetallic strip 5 and the first single cell. Furthermore, a groove can be provided in the center of the upper fixed plate 1, and the thermal bimetallic strip 5 is embedded in the groove of the upper fixed plate 1. Alternatively, the thermal bimetallic strip 5 can be in direct contact with the upper fixed plate 1, and the upper fixed plate 1 does not have a groove.

[0031] Installation method 2: the single cell closest to the lower fixed plate 4 among the single cells 2 is the second single cell, the thermal bimetallic strip 5 can be located between the lower fixed plate 4 and the second single cell, and a hard metal sheet 3 is sandwiched between the thermal bimetallic strip 5 and the second single cell. Furthermore, a groove can be provided in the center of the lower fixed plate 4, and the thermal bimetallic strip 5 is embedded in the groove of the lower fixed plate 4. Alternatively, the thermal bimetallic strip 5 can be in direct contact with the lower fixed plate 4, and the lower fixed plate 4 does not have a groove.

[0032] Installation mode three: the thermal bimetallic strip 5 can be located between the third single cell and the fourth single cell, which are two adjacent single cells. A hard metal strip 3 is sandwiched between the thermal bimetallic strip 5 and the third single cell, and a hard metal strip 3 is also sandwiched between the thermal bimetallic strip 5 and the fourth single cell.

[0033] In the installation method 1 or the installation method 2, the depth of the groove is 0.5 mm to 4 mm, and the diameter of the groove is 5 mm to 6 mm smaller than the diameter of the fixing plate where the groove is located.

[0034] In the first installation method or the second installation method, the diameter of the thermal bimetallic strip 5 is the same as the diameter of the groove.

[0035] In the installation method 1 or the installation method 2, the number of the n thermal bimetallic strips 5 is related to the depth of the groove, and the total thickness of the n thermal bimetallic strips 5 is equal to the depth of the groove.

[0036] In the third installation method, the diameter of the thermal bimetallic strip 5 is the same as the diameter of the upper fixing plate 1 or the lower fixing plate 4 .

[0037] The number n of the thermal bimetallic strips 5 and the thickness h of a single thermal bimetallic strip are related to the diameter d of the thermal bimetallic strip 5 , the temperature curvature k, the thermal shrinkage t before and after activation of the single battery 2 , and the number n0 .

[0038] Optionally, the n thermal bimetallic strips 5 should satisfy that the total deformation of the n thermal bimetallic strips 5 does not exceed D1 (D1 may be 0.5 to 2 mm, D1 is, for example, 1 mm) when the thermal battery is stored at high temperature. The design requirements are:

[0039]

[0040] Wherein ΔT1 is the temperature change under high temperature storage state. In one embodiment, according to the margin design principle, ΔT1 can be 100K.

[0041] Optionally, the n thermal bimetallic strips 5 should satisfy the requirement that when the thermal battery is activated, the total deformation amount compensates for the thickness shrinkage amount of the single battery 2, so that the total deformation amount of the thermal battery stack does not exceed D2 (D2 may be 0.5-2 mm, D2 is, for example, 1 mm). The design requirements are:

[0042]

[0043] Wherein ΔT2 is the temperature change before and after the thermal battery is activated. In one embodiment, ΔT2 is 500K.

[0044] Optionally, at least one of the upper fixing plate 1 and the lower fixing plate 4 has a thickness of 3 mm to 5 mm.

[0045] Optionally, the operating temperature of the n thermal bimetallic strips 5 is 300-600° C., and the total thickness of the n thermal bimetallic strips 5 is 0.5 mm-4 mm.

[0046] Optionally, the diameter of the hard metal sheet 3 is the same as the diameter of the upper fixed plate 1 / lower fixed plate 4, the thickness of the hard metal sheet 3 is 0.5mm~2mm, and the hard metal sheet 3 can be a stainless steel sheet or a titanium alloy sheet or a Fe-KClO4 heating sheet used in the field of thermal batteries.

[0047] The thermal battery stack described in the present invention should have other auxiliary structures and components necessary for the thermal battery stack in addition to the structures such as the fixing plate 1, the single battery cell 2, the thermal bimetallic sheet 5 and the hard metal sheet 3. The above-mentioned components or auxiliary structures can be made of materials, designs and assembly methods well known to those skilled in the art.

[0048] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Example 1

[0050] Prepare 96 single thermal batteries with a diameter of 75mm, 1 thermal bimetallic sheet with a brand of 5J2270, a diameter of 75mm and a thickness of 1.5mm, 2 fixing plates with a diameter of 75mm and a thickness of 3mm (used as the upper fixing plate and the lower fixing plate respectively), and 1 titanium alloy sheet with a diameter of 75mm and a thickness of 1.5mm. From bottom to top, the battery stack is composed of a lower fixing plate, a thermal bimetallic sheet, a titanium alloy sheet, 96 single batteries, an upper fixing plate, and other necessary auxiliary structures and parts, and the battery stack is assembled into a unit battery.

[0051] The thermal bimetallic strip was replaced with a common metal strip of the same size and weight, and the other parts remained unchanged. The control unit battery was assembled and a discharge test was performed under the same environment and load. The discharge test curves of the two unit batteries are shown in Figure 2. Figure 2 ,The output voltage, pulse voltage and working time of the battery using thermal bimetallic strips are better than those of the control battery.

[0052] Example 2

[0053] Prepare 72 single thermal batteries with a diameter of 75mm, a thermal bimetallic sheet of brand 5J2270, a diameter of 70mm, and a thickness of 2mm, an upper fixed plate with a diameter of 75mm and a thickness of 3mm, a lower fixed plate with a diameter of 75mm and a thickness of 5mm and a groove with a diameter of 69mm and a depth of 2mm, and a titanium alloy sheet with a diameter of 75mm and a thickness of 2mm. From bottom to top, the battery stack is composed of a lower fixed plate with a groove, a thermal bimetallic sheet, a titanium alloy sheet, 72 single batteries, an upper fixed plate, and other necessary auxiliary structures and parts, and the battery stack is assembled into a unit battery.

[0054] Example 3

[0055] Prepare 64 single thermal batteries with a diameter of 40mm, 1 thermal bimetallic sheet of brand 5J1970, 40mm in diameter and 0.5mm in thickness, 2 stainless steel sheets with a diameter of 40mm and a thickness of 0.5mm, and 2 fixing plates with a diameter of 40mm and a thickness of 3mm (used as the upper fixing plate and the lower fixing plate respectively). From bottom to top, the battery stack is composed of the lower fixing plate, 32 single batteries, stainless steel sheet, 1 thermal bimetallic sheet, stainless steel sheet, 32 single batteries, the upper fixing plate, and other necessary auxiliary structures and parts, and the battery stack is assembled into a unit battery.

[0056] Example 4

[0057] Prepare 48 single thermal batteries with a diameter of 40mm, a thermal bimetallic sheet of brand 5J1970, a diameter of 35mm, and a thickness of 0.5mm, an upper fixing plate with a diameter of 40mm and a thickness of 3mm, a lower fixing plate with a diameter of 40mm and a thickness of 3mm and a groove of 35mm and a depth of 0.5mm, and a stainless steel sheet with a diameter of 40mm and a thickness of 0.5mm. From bottom to top, the battery stack is composed of a lower fixing plate with a groove, a thermal bimetallic sheet, a stainless steel sheet, 48 single batteries, an upper fixing plate, and other necessary auxiliary structures and parts, and the battery stack is assembled into a unit battery.

[0058] Example 5

[0059] Prepare 32 single thermal batteries with a diameter of 22mm, 2 thermal bimetallic strips of brand 5J1356, 22mm in diameter and 0.5mm in thickness, 2 fixing plates with a diameter of 22mm (used as upper fixing plates and lower fixing plates respectively), and 2 stainless steel metal sheets with a thickness of 0.5mm and a diameter of 22mm. From bottom to top, the battery stack is composed of a lower fixing plate, 16 single batteries, a stainless steel metal sheet, 2 thermal bimetallic strips, a stainless steel metal sheet, 16 single batteries, an upper fixing plate, and other necessary auxiliary structures and parts, and the battery stack is assembled into a unit battery.

[0060] Although the present invention is disclosed as above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims of the present invention.

Claims

1. A thermal battery stack with a height self-regulating function, comprising an upper fixing plate (1), a plurality of single cells (2), and a lower fixing plate (4); characterized in that: It also comprises n thermal bimetallic sheets (5) and at least one hard metal sheet (3), where n is a positive integer; the n thermal bimetallic sheets (5) are arranged between the upper fixed plate (1) and the lower fixed plate (4), and the hard metal sheet (3) is arranged adjacent to the thermal bimetallic sheets (5).

2. The thermal battery stack according to claim 1, characterized in that: Before and after the thermal battery is activated, the n thermal bimetallic strips (5) satisfy: h is the thickness of a single thermal bimetallic strip (5), k is the thermal curvature of the thermal bimetallic strip (5), ΔT2 is the temperature change before and after the thermal battery is activated, d is the diameter of the thermal bimetallic strip (5), t is the thermal contraction amount of the single battery (2) before and after activation, n0 is the number of single batteries (2), and D1 is the preset threshold value of the total deformation amount of the thermal battery stack before and after activation.

3. The thermal battery stack according to claim 1 or 2, characterized in that: In the high temperature storage state of the thermal battery, the n thermal bimetallic strips (5) satisfy: h is the thickness of a single thermal bimetallic strip (5), k is the thermal curvature of the thermal bimetallic strip (5), ΔT1 is the temperature change under high-temperature storage conditions, d is the diameter of the thermal bimetallic strip (5), and D1 is the preset threshold value of the total deformation of n thermal bimetallic strips (5) under high-temperature storage conditions.

4. The thermal battery stack according to claim 1, characterized in that: The installation of the thermal bimetallic strip (5) satisfies any of the following conditions: The single cell (2) closest to the upper fixing plate (1) among the plurality of single cells (2) is a first single cell, the thermal bimetallic sheet (5) is located between the upper fixing plate (1) and the first single cell, and a hard metal sheet (3) is sandwiched between the thermal bimetallic sheet (5) and the first single cell; The single cell (2) closest to the lower fixing plate (4) among the plurality of single cells (2) is a second single cell, the thermal bimetallic sheet (5) is located between the lower fixing plate (4) and the second single cell, and a hard metal sheet (3) is sandwiched between the thermal bimetallic sheet (5) and the second single cell; The thermal bimetallic strip (5) is located between a third single cell and a fourth single cell, and the third single cell and the fourth single cell are two adjacent single cells (2); a hard metal sheet (3) is sandwiched between the thermal bimetallic strip (5) and the third single cell, and a hard metal sheet (3) is also sandwiched between the thermal bimetallic strip (5) and the fourth single cell.

5. The thermal battery stack according to claim 4, characterized in that: A groove is provided at the center of the upper fixing plate (1) or the lower fixing plate (4), and a thermal bimetallic strip (5) is embedded in the groove.

6. The thermal battery stack according to claim 5, characterized in that: The depth of the groove is 0.5 mm to 4 mm, the diameter of the groove is 5 mm to 6 mm smaller than the diameter of the fixed plate where the groove is located, the diameter of the thermal bimetallic strip (5) is the same as the diameter of the groove, and the total thickness of n thermal bimetallic strips (5) is equal to the depth of the groove.

7. The thermal battery stack according to claim 4, characterized in that: The diameter of the thermal bimetallic strip (5) is the same as the diameter of the upper fixing plate (1) or the lower fixing plate (4).

8. The thermal battery stack according to claim 1, characterized in that: The thickness of at least one of the upper fixing plate (1) and the lower fixing plate (4) is 3 mm to 5 mm.

9. The thermal battery stack according to claim 1, characterized in that: The use temperature of the n thermal bimetallic strips (5) is 300-600° C., and the total thickness of the n thermal bimetallic strips (5) is 0.5 mm-4 mm.

10. The thermal battery stack according to claim 1, characterized in that: The diameter of the hard metal sheet (3) is the same as the diameter of the upper fixing plate (1) / lower fixing plate (4), the thickness of the hard metal sheet (3) is 0.5 mm to 2 mm, and the hard metal sheet (3) is a stainless steel sheet or a titanium alloy sheet or a Fe-KClO4 heating sheet.

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