Electrolyte anti-overflow type thermal battery two-layer electrode plate and preparation method thereof

Abstract

The invention discloses an electrolyte anti-overflow type thermal battery two-layer electrode plate and a preparation method thereof. The two-layer electrode plate comprises a positive electrode layer, an isolating layer and an insulating lantern ring; the positive electrode layer and the isolation layer are of a cylindrical structure, the insulation lantern ring is of a center hole cylindrical structure, and the periphery of the isolation layer is wrapped by the insulation lantern ring. The outer diameters of the insulating lantern ring and the positive electrode layer are the same, the upper surface of the insulating lantern ring is provided with an embedded interface layer area covered by the positive electrode layer and the isolating layer, and powder of the positive electrode layer cannot penetrate downwards through gaps among the isolating layer, the insulating lantern ring and the mold. On one hand, the risk of short circuit caused by overflow of electrolyte at high temperature can be eliminated by means of the complete wrapping effect of the insulating lantern ring and the positive electrode layer on the side face of the isolating layer, and on the other hand, the high-reliability two-layer electrode plate prepared based on screwing and pre-pressing of the powder layer can reduce the phenomena of non-uniformity of the powder layer, permeation short circuit of the positive electrode layer and damage of the isolating layer after demolding. The preparation qualification rate and efficiency of the two layers of electrode plates and the working safety of the thermal battery are improved, and the method has engineering application value.

Description

Technical Field

[0001] The present application relates to the technical field of thermal batteries, and in particular to a two-layer electrode sheet of an electrolyte overflow-proof thermal battery and a preparation method thereof. Background Art

[0002] Thermal batteries are heat-activated batteries, which rely on their own heating system to melt solid molten salt and activate them as disposable storage batteries. They have the advantages of short activation time, long storage time and maintenance-free.

[0003] The requirements for specific energy and specific power of thermal batteries are constantly increasing, and thin, large-size electrode sheet structure design has become the mainstream; Figure 1 The two-layer electrode sheet shown, which consists of a positive electrode layer and an isolation layer (a mixture of a halogen eutectic salt electrolyte and MgO), is increasingly used in current thermal battery products because the overall safety of the single cell is higher than that of the three-layer sheet and the four-layer sheet and is more suitable for long-term large-pulse power consumption environments.

[0004] Conventional manual film-making methods are difficult to prepare thin, large-sized electrode sheets. The thickness of the uncompacted single-layer powder layer of a two-layer electrode sheet is about 1mm at its thinnest. When the size of the electrode sheet is above Φ50mm, it is difficult to ensure the uniformity of the powder layer by manually flattening it, and it is easy to disturb the already flattened powder layer, which has an adverse effect on the physical structure and electrical performance consistency of the product and the molding pass rate. At the same time, due to the low strength of the thin two-layer electrode sheet, the isolation layer may crack due to the friction between the mold and the mold during demolding, resulting in unqualified electrode sheets. At present, the pass rate of manual preparation of traditional two-layer electrode sheets is less than 70%, the efficiency is less than 2min / sheet, and product consistency is difficult to guarantee.

[0005] When the thermal battery is working, the temperature can rise to about 500°C. The electrolyte will be in a semi-molten state at this time. Under the condition of large-scale mechanical vibration, it may overflow, causing a short circuit between adjacent electrode sheets, affecting the safety of the battery. The existing technologies for solving the above problems will either cause the electrode sheet structure to be too complicated, the electrode sheet to be difficult to scrape flat, the monomer assembly to be difficult, the overall manufacturing efficiency to be low, and the engineering application to be difficult; or it will cause the insulating collar and the isolation layer to be difficult to achieve precise size matching, and the side of the isolation layer cannot be completely covered; when using the traditional manual scraping-pressing process, the insulating collar, the isolation layer, and the mold are not tightly combined and there is a gap. During the scraping and pressing process, the positive electrode powder is easy to penetrate and difficult to detect, which will affect the qualified rate of the electrode sheet at the least, and cause a short circuit when the thermal battery is working, bringing new safety risks. Summary of the invention

[0006] In order to solve the technical problems that the thin and large-sized two-layer electrode sheets are difficult to prepare, have a low qualified rate, and the electrolyte is easy to overflow, the present invention proposes an electrolyte overflow-proof thermal battery two-layer electrode sheet and a preparation method thereof.

[0007] In a first aspect, a two-layer electrode sheet of an electrolyte overflow-proof thermal battery is provided, wherein the two-layer electrode sheet comprises a positive electrode layer, a separation layer, and an insulating ring; the positive electrode layer and the separation layer are both cylindrical structures, the insulating ring is a mesoporous cylindrical structure, the outer periphery of the main part of the separation layer is wrapped by the insulating ring, the positive electrode layer covers the isolation layer and the insulating ring, and the outer diameter of the insulating ring is the same as the outer diameter of the positive electrode layer; the positive electrode layer has a chamfer on the side facing the insulating ring, and the separation layer is filled in the space formed by the chamfer to prevent the material of the positive electrode layer from penetrating downward through the gap between the main part of the separation layer and the insulating ring.

[0008] In combination with the first aspect, in some implementations of the first aspect, the insulating ring satisfies at least one of the following:

[0009] The insulating collar comprises at least one of the following high temperature resistant insulating materials: asbestos, aluminum silicate fiber wool, mica;

[0010] The thickness of the insulating sleeve ring is in the range of 0.3 mm to 0.5 mm, the width is 1 mm to 2 mm, and the outer diameter is the same as the nominal diameter of the two-layer electrode sheet of the electrolyte overflow-proof thermal battery.

[0011] In combination with the first aspect, in certain implementations of the first aspect, the isolation layer is a powder mixture of one or more halogen eutectic salts and MgO, and the halogen eutectic salts include at least one of the following: LiCl, LiBr, LiF, KCl.

[0012] In combination with the first aspect, in some implementations of the first aspect, the positive electrode layer satisfies at least one of the following:

[0013] The positive electrode layer is a powder mixture of one or more of FeS2, CoS2 and halogen eutectic salt.

[0014] In combination with the first aspect, in certain implementations of the first aspect, the thickness of the two-layer electrode sheet of the electrolyte overflow-proof thermal battery is in the range of 1 mm to 2 mm, and the diameter is in the range of Φ50 mm to Φ80 mm.

[0015] In a second aspect, a method for preparing a two-layer electrode sheet of an electrolyte overflow-proof thermal battery as described in any one of the implementations of the first aspect is provided, comprising:

[0016] The insulating sleeve is placed in the mold, and the insulating sleeve is pressed around with a limiting sleeve, wherein the limiting sleeve has a chamfer at the bottom facing the insulating sleeve;

[0017] Pour the weighed isolation layer powder into the mold so that the isolation layer powder fills the insulating collar. The excess powder that does not enter the insulating collar is accumulated in the limiting sleeve. Use the screwing head to screw the isolation layer powder flat, and then remove the screwing head.

[0018] Put a pre-pressing head in the mold, and use a press to pre-press and compact the isolation layer powder so that the isolation layer powder fills the space formed by the chamfer of the limiting sleeve;

[0019] Remove the mold from the press, and remove the limiting sleeve and the pre-pressing head;

[0020] Pour the weighed positive electrode layer powder into the mold, use the screwing press to screw the positive electrode layer powder flat, and then remove the screwing press;

[0021] A molding press is placed in the mold, and a press is used to press and mold the mold, and after demolding, the electrolyte overflow-proof thermal battery two-layer electrode sheet according to claim 1 is obtained.

[0022] In combination with the second aspect, in some implementations of the second aspect, the outer wall diameter of the limiting sleeve is the same as the nominal outer diameter of the insulating ring, the inner wall diameter is the same as the nominal inner diameter of the insulating ring, the chamfer angle of the bottom of the inner wall is α=45°, and the chamfer height is 0.2 mm. <A<0.4mm。

[0023] In combination with the second aspect, in certain implementations of the second aspect, the diameter of the screwing head used for screwing the isolation layer powder is the same as the nominal size of the inner diameter of the limiting sleeve, the diameter of the screwing head used for screwing the positive electrode layer powder is the same as the nominal size of the diameter of the two-layer electrode sheets of the electrolyte overflow-proof thermal battery, and the surface of the head is distributed with hemispherical bumps with a radius of 0.2mm to 0.5mm, which are used to improve the uniformity of the distribution of the viscous electrode powder.

[0024] In combination with the second aspect, in certain implementations of the second aspect, the screwing pressure head presses the powder layer and rotates one circle clockwise and one circle counterclockwise as one action cycle. When screwing the isolation layer powder, it is screwed for 3 to 5 cycles, and when screwing the positive electrode layer powder, it is screwed for 2 to 4 cycles.

[0025] In conjunction with the second aspect, in certain implementations of the second aspect, the preparation method satisfies at least one of the following:

[0026] The diameter of the preloading head is the same as the nominal size of the inner diameter of the limiting sleeve, and the preloading pressure is 50kN~200kN;

[0027] The diameter of the molding pressure head is the same as the nominal size of the diameter of the two-layer electrode sheet of the electrolyte overflow-proof thermal battery, and the molding pressure is 500kN to 2000kN.

[0028] Compared with the prior art, the solution provided by this application includes at least the following beneficial technical effects:

[0029] Firstly, a mosaic interface layer of positive electrode layer, insulating sleeve and isolation layer is designed. The side of the isolation layer is completely wrapped by the insulating sleeve and the positive electrode layer, which can eliminate the risk of short circuit between electrode sheets caused by high-temperature electrolyte overflow and improve the working safety of the thermal battery. Secondly, due to the introduction of the isolation layer pre-pressing process, the insulating sleeve and the isolation layer are shaped, so that the insulating sleeve, the isolation layer and the mold are tightly combined, avoiding the risk of downward penetration of the positive electrode layer during the preparation and operation of the electrode sheet. Thirdly, the mosaic interface layer can effectively improve the structural strength of the electrode sheet, reduce the risk of damage during demolding, subsequent assembly processes and product use, and improve reliability. Fourthly, the powder layer is flattened based on the screwing pressure head, and the isolation layer pre-pressing and compacting process is added, which solves the problems of poor uniformity of the powder layer, low preparation efficiency and low molding qualification rate of the two-layer electrode sheets of thin and large-size thermal batteries. The preparation efficiency of a single electrode sheet can reach 60s / sheet, and the molding qualification rate is more than 92%, which has engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the traditional thermal battery two-layer electrode structure.

[0031] Figure 2 It is a schematic diagram of the structure of the two-layer electrode sheet of the thermal battery of the present invention.

[0032] Figure 3 It is a schematic diagram of a limiting sleeve for auxiliary forming proposed by the present invention.

[0033] Figure 4 It is a schematic diagram of the combined relationship of the insulating sleeve ring, the isolation layer and the limiting sleeve after being twisted and flattened proposed by the present invention.

[0034] Figure 5 It is a schematic diagram of a screwing press head for leveling a powder layer proposed by the present invention.

[0035] Description of reference numerals:

[0036] 1. Positive electrode layer, 2. Isolation layer, 3. Insulating ring, 4. Limiting sleeve, 5. Screw pressure head. DETAILED DESCRIPTION

[0037] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Figure 2A two-layer electrode sheet of an electrolyte overflow-proof thermal battery provided by the present invention is shown. The two-layer electrode sheet includes a positive electrode layer 1, a separation layer 2, and an insulating ring 3. The positive electrode layer 1 and the separation layer 2 are both cylindrical structures, the insulating ring 3 is a mesoporous cylindrical structure, and the main part of the separation layer 2 is wrapped by the insulating ring 3. The positive electrode layer 1 covers the isolation layer 2 and the insulating ring 3, and the insulating ring 3 and the positive electrode layer 1 have the same outer diameter. The positive electrode layer 1 has a chamfer on the side facing the insulating ring 3, and the separation layer 2 is filled in the space formed by the chamfer, so that a mosaic interface layer area covered by the positive electrode layer 1 and the separation layer 2 is formed on the upper surface of the insulating ring 3, which is used to prevent the material of the positive electrode layer 1 from penetrating downward through the gap between the isolation layer 2 and the insulating ring 3.

[0039] Furthermore, the insulating ring 3 includes but is not limited to high temperature resistant insulating materials such as asbestos, aluminum silicate fiber wool, and mica.

[0040] Furthermore, the thickness of the insulating sleeve 3 is in the range of 0.3 mm to 0.5 mm, the width is 1 mm to 2 mm, and the outer diameter is the same as the nominal diameter of the electrode sheet.

[0041] Furthermore, the isolation layer 2 is a powder mixture of one or more halogen eutectic salts such as LiCl, LiBr, LiF, KCl and MgO.

[0042] Furthermore, the positive electrode layer 1 is a powder mixture of one or more of FeS2, CoS2 and halogen eutectic salt.

[0043] Furthermore, the thickness range of the applicable electrode sheet is 1 mm to 2 mm, and the diameter range is Φ50 mm to Φ80 mm.

[0044] The present invention also provides a method for preparing a two-layer electrode sheet of an electrolyte overflow-proof thermal battery, comprising the following steps.

[0045] Step 1: Place the insulating sleeve 3 in the mold, and use the limiting sleeve 4 to press the surrounding of the insulating sleeve 3, wherein the limiting sleeve 4 has a chamfer at the bottom facing the insulating sleeve 3;

[0046] Step 2: Pour the weighed powder of the isolation layer 2 into the mold, so that the powder of the isolation layer 2 fills the insulating collar 3, and the excess powder that does not enter the insulating collar 3 is accumulated in the limiting sleeve 4. Use the screwing head 5 to screw and level the powder of the isolation layer 2, and then remove the screwing head 5;

[0047] Step 3: Place a pre-pressing head in the mold, and use a press to pre-press and compact the powder of the isolation layer 2 so that the powder of the isolation layer 2 fills the space formed by the chamfer of the limiting sleeve 4;

[0048] Step 4: Take out the mold from the press, and take out the limiting sleeve 4 and the pre-pressing head;

[0049] Step 5: Pour the weighed positive electrode layer 1 powder into the mold, use the screwing press head 5 to screw the positive electrode layer 1 powder to make it flat, and then take out the screwing press head 5;

[0050] Step 6: Place a molding press in the mold, use a press to press the electrode sheet into shape, and then demold it through a demolding device to obtain the electrode sheet.

[0051] Furthermore, the outer wall size of the limiting sleeve 4 is the same as the outer diameter size of the insulating sleeve 3, the inner wall size of the limiting sleeve 4 is the same as the inner diameter size of the insulating sleeve 3, the chamfer angle size of the bottom of the inner wall is α=45°, and the chamfer height size is 0.2mm <A<0.4mm。

[0052] Furthermore, during the screwing process, the diameter of the screwing head 5 corresponding to the isolation layer 2 is the same as the nominal size of the inner diameter of the limiting sleeve 4, and the diameter of the screwing head 5 corresponding to the positive electrode layer 1 is the same as the nominal size of the electrode sheet diameter. Hemispherical bumps with a radius of 0.2mm to 0.5mm are distributed on the surface of the head to improve the uniformity of the distribution of the viscous electrode powder.

[0053] Furthermore, during the twisting process, the twisting head 5 presses the powder layer and rotates one circle clockwise and one circle counterclockwise as one action cycle. The isolation layer 2 powder is twisted for 3 to 5 cycles, and the positive electrode layer 1 powder is twisted for 2 to 4 cycles.

[0054] Furthermore, during the pre-pressing process, the diameter of the pre-pressing head is the same as the nominal size of the inner diameter of the limiting sleeve 4, and the pre-pressing pressure is 50 kN to 200 kN.

[0055] Furthermore, in the pressing process, the diameter of the forming press head is the same as the nominal size of the electrode sheet diameter, and the forming pressure is 500 kN to 2000 kN.

[0056] Embodiment 1:

[0057] Step 1: Place a mica insulating sleeve 3 with a thickness of 0.3 mm and a width of 1 mm in a mold with a diameter of 65 mm, and use a limiting sleeve 4 with a chamfer height of 0.2 mm to press the insulating sleeve 3 around;

[0058] Step 2: Pour the weighed isolation layer 2 powder (LiCl-KCl and MgO mixture, weight 3.20 g) into the mold, use a 63 mm diameter screw head 5 to screw for 3 cycles to level the isolation layer 2 powder, the radius of the hemispherical convex point on the screw head 5 is 0.3 mm, and then take out the screw head 5;

[0059] Step 3: Place a pre-pressing head in the mold, and use a press to pre-press and compact the powder of the isolation layer 2, with a pre-pressing pressure of 100 kN to compact the powder of the isolation layer 2;

[0060] Step 4: Take out the mold from the press, and take out the limiting sleeve 4 and the pre-pressing head;

[0061] Step 5: Pour the weighed positive electrode layer 1 powder (FeS2 and LiCl-KCl mixture, weight 6.78g) into the mold, use a 65mm diameter screw head 5 to screw for 2 cycles to level the positive electrode layer 1 powder, the radius of the hemispherical convex point on the screw head 5 is 0.3mm, and then take out the screw head 5;

[0062] Step 6: Place a molding press in the mold, place the mold in a press, set the molding pressure to 1000 kN, press the electrode sheet into shape, and demold it through a demolding device to obtain the electrode sheet.

[0063] Embodiment 2:

[0064] Step 1: Place an asbestos insulating sleeve 3 with a thickness of 0.5 mm and a width of 2 mm in a mold with a diameter of 80 mm, and use a limiting sleeve 4 with a chamfer height of 0.4 mm to press around the insulating sleeve 3;

[0065] Step 2: Pour the weighed isolation layer 2 powder (LiCl-LiBr-LiF and MgO mixture, weight 6.34 g) into the mold, use a 76 mm diameter screw head 5 to screw for 5 cycles to level the isolation layer 2 powder, the radius of the hemispherical convex point on the screw head 5 is 0.5 mm, and then take out the screw head 5;

[0066] Step 3: Place a pre-pressing head in the mold, and use a press to pre-press and compact the powder of the isolation layer 2, with a pre-pressing pressure of 200 kN to compact the powder of the isolation layer 2;

[0067] Step 4: Take out the mold from the press, and take out the limiting sleeve 4 and the pre-pressing head;

[0068] Step 5: Pour the weighed positive electrode layer 1 powder (mixture of CoS2 and LiCl-LiBr-LiF, weight 19.23 g) into the mold, and use a screwing head 5 with a diameter of 80 mm to screw for 4 cycles to level the positive electrode layer 1 powder. The radius of the hemispherical convex point on the screwing head 5 is 0.5 mm, and then take out the screwing head 5;

[0069] Step 6: Place a molding press in the mold, place the mold in a press, set the molding pressure at 2000 kN, press the electrode sheet into shape, and demold it through a demolding device to obtain the electrode sheet.

[0070] Although the present invention is disclosed as above in the form of a preferred embodiment, 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 two-layer electrode sheet for an electrolyte overflow-proof thermal battery, characterized in that: The two-layer electrode sheet comprises a positive electrode layer (1), a separation layer (2), and an insulating sleeve (3); the positive electrode layer (1) and the separation layer (2) are both cylindrical structures, the insulating sleeve (3) is a mesoporous cylindrical structure, the main body of the separation layer (2) is wrapped by the insulating sleeve (3), the positive electrode layer (1) covers the separation layer (2) and the insulating sleeve (3), and the outer diameter of the insulating sleeve (3) is the same as the outer diameter of the positive electrode layer (1); the positive electrode layer (1) has a chamfer on the side facing the insulating sleeve (3), and the separation layer (2) is filled in the space formed by the chamfer to prevent the material of the positive electrode layer (1) from penetrating downward through the gap between the main body of the separation layer (2) and the insulating sleeve (3).

2. The electrolyte overflow-proof thermal battery two-layer electrode sheet according to claim 1, characterized in that: The insulating sleeve (3) satisfies at least one of the following conditions: The insulating sleeve (3) comprises at least one of the following high temperature resistant insulating materials: asbestos, aluminum silicate fiber wool, mica; The insulating sleeve (3) has a thickness ranging from 0.3 mm to 0.5 mm, a width ranging from 1 mm to 2 mm, and an outer diameter which is the same as the nominal diameter of the two-layer electrode sheet of the electrolyte overflow-proof thermal battery.

3. The electrolyte overflow-proof thermal battery two-layer electrode sheet according to claim 1, characterized in that: The isolation layer (2) is a powder mixture of one or more halogen eutectic salts and MgO, and the halogen eutectic salts include at least one of the following: LiCl, LiBr, LiF, KCl.

4. The electrolyte overflow-proof thermal battery two-layer electrode sheet according to claim 1, characterized in that: The positive electrode layer (1) satisfies at least one of the following: The positive electrode layer (1) is a powder mixture of one or more of FeS2, CoS2 and halogen eutectic salt.

5. The electrolyte overflow-proof thermal battery two-layer electrode sheet according to claim 1, characterized in that: The thickness of the two-layer electrode sheet of the electrolyte overflow-proof thermal battery is in the range of 1 mm to 2 mm, and the diameter is in the range of Φ50 mm to Φ80 mm.

6. A method for preparing a two-layer electrode sheet of an electrolyte overflow-proof thermal battery according to any one of claims 1 to 5, characterized in that: include: The insulating sleeve (3) is placed in the mold, and the insulating sleeve (3) is pressed around with a limiting sleeve (4), wherein the limiting sleeve (4) has a chamfered bottom facing the insulating sleeve (3); Pour the weighed powder of the isolation layer (2) into the mold, so that the powder of the isolation layer (2) fills the insulating collar (3), and the excess powder that does not enter the insulating collar (3) is accumulated in the limiting sleeve (4), and the powder of the isolation layer (2) is leveled by twisting with a twisting press head (5), and then the twisting press head (5) is removed; A pre-pressing head is placed in the mold, and a press is used to pre-press and compact the powder of the isolation layer (2), so that the powder of the isolation layer (2) fills the space formed by the chamfer of the limiting sleeve (4); The mold is removed from the press, and the limiting sleeve (4) and the pre-pressing head are removed; Pour the weighed positive electrode layer powder into the mold, use a screwing press (5) to screw the positive electrode layer (1) powder to make it flat, and then remove the screwing press (5); A molding press is placed in the mold, and a press is used to press and mold the mold, and after demolding, the electrolyte overflow-proof thermal battery two-layer electrode sheet according to claim 1 is obtained.

7. The preparation method according to claim 6, characterized in that: The outer diameter of the limiting sleeve (4) is the same as the nominal outer diameter of the insulating sleeve (3), the inner diameter is the same as the nominal inner diameter of the insulating sleeve (3), the chamfer angle of the bottom of the inner wall is α=45°, and the chamfer height is 0.2 mm. <A<0.4mm。 8. The preparation method according to claim 6, characterized in that: The diameter of the screwing head (5) used to screw the isolation layer (2) powder is the same as the nominal size of the inner diameter of the limiting sleeve (4), and the diameter of the screwing head (5) used to screw the positive electrode layer (1) powder is the same as the nominal size of the diameter of the two-layer electrode sheet of the electrolyte overflow-proof thermal battery. The surface of the head is distributed with hemispherical protrusions with a radius of 0.2 mm to 0.5 mm, which are used to improve the uniformity of the distribution of the viscous electrode powder.

9. The preparation method according to claim 6, characterized in that: The screwing pressing head (5) presses the powder layer and rotates one circle clockwise and one circle counterclockwise respectively as one action cycle. When the isolation layer (2) powder is screwed, 3 to 5 cycles are screwed, and when the positive electrode layer (1) powder is screwed, 2 to 4 cycles are screwed.

10. The preparation method according to claim 6, characterized in that: The preparation method satisfies at least one of the following: The diameter of the pre-pressing head is the same as the nominal size of the inner diameter of the limiting sleeve (4), and the pre-pressing pressure is 50kN to 200kN; The diameter of the molding pressure head is the same as the nominal size of the diameter of the two-layer electrode sheet of the electrolyte overflow-proof thermal battery, and the molding pressure is 500kN to 2000kN.

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