A single cell battery and composite sheet used therein, and a method for preparing the composite sheet

Abstract

This invention discloses a composite sheet in the field of thermal battery technology. The sheet comprises a heating powder, a positive electrode material, and a nano-diaphragm powder, which are laminated and pressed together. The heating powder is a mixture of micro-nano iron powder and potassium perchlorate in a weight ratio of 70-90:10-25. The positive electrode material comprises components and their usage ratios of disulfide: electrolyte: adsorbent: high-thermal-conductivity graphene in the order of 65-85:5-10:3-10:7-15, with the adsorbent being MgO or Al2O3. The nano-diaphragm powder is a mixture of electrolyte and MgO in a ratio of 50-65:35-50, heated and melted, and then formed into particles with a size of less than 10 μm. The composite sheet obtained by this invention can be used to prepare a novel fast-activation single-cell battery, shortening activation time by over 50% compared to conventional single-cell batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal batteries, and in particular relates to a single cell battery, a composite sheet used therein, and a method for preparing the composite sheet. Background Art

[0002] A thermal battery is a heat-activated reserve battery that operates by heating a non-conductive solid salt electrolyte to melt and form an ionic conductor. Thermal batteries feature properties such as activation at any angle, rapid activation, long storage life, and robust resistance to environmental mechanical conditions. They are widely used in weapon systems and other applications. Furthermore, their civilian applications are gaining attention, with reports on their use as emergency power sources for aircraft, fire alarms, and underground high-temperature prospecting.

[0003] The key development direction of the new generation of weapons is to have the characteristics of rapid response and high strike accuracy, so the development of a new generation of weapon systems is of great significance. According to the combat technology characteristics and power supply requirements of the new generation of weapons, rapid activation of thermal batteries can provide technical support for the rapid response of weapons, thereby improving the performance of the new generation of portable missile weapons. The thermal battery activation process is shown in the attached figure. Figure 1 The detonation time of the primer can be guaranteed to be within 10ms. The activation time is determined by the time it takes for the ignition paper to burn, the heating plate to burn, the heat transfer, and the melting of the electrolyte. Therefore, key technologies such as rapid ignition technology, high-burning-rate heating powder technology, high-thermal-conductivity electrode material preparation technology, and low-melting-point, high-conductivity electrolyte technology must be tackled to shorten the activation time of the thermal battery. Summary of the Invention

[0004] The present invention aims to provide a composite sheet which is applied to the preparation of a thermal battery, improves the ignition speed, and shortens the activation time of the thermal battery.

[0005] A composite sheet in this scheme includes heating powder, positive electrode material and nano-membrane powder, which are stacked and pressed in sequence. The heating powder is a mixture of micro-nano iron powder and potassium perchlorate in a weight ratio of 70-90:10-25; the components included in the positive electrode material and the usage ratio of the components are disulfide: electrolyte: adsorbent: high thermal conductivity graphene = 65-85:5-10:3-10:7-15, and the adsorbent is MgO or Al2O3; the nano-membrane powder is an electrolyte and MgO mixed in a ratio of 50-65:35-50, heated and melted, and then prepared into particles with a particle size of less than 10 μm.

[0006] Furthermore, the disulfide is one of FeS2, CoS2, NiS2, WS2, and MoS2.

[0007] Furthermore, the electrolyte used in the positive electrode material is KCl-LiCl, and the electrolyte used in the nano-diaphragm is LiBr-KBr-CsBr.

[0008] The present invention also provides a method for preparing the composite sheet for thermal batteries, comprising:

[0009] (1) Preparation of heating powder: Mix micro-nano iron powder and potassium perchlorate in a weight ratio and set aside;

[0010] (2) Preparation of positive electrode material: calcining disulfide at 450℃~500℃ under inert gas for more than 2h, then crushing and sieving the calcined disulfide, retaining 200-300 mesh disulfide powder, adding electrolyte and mixing evenly, then adding adsorbent and mixing evenly, finally adding high thermal conductivity graphene and mixing evenly, then drying at 150℃~300℃ under inert gas, then crushing and screening out fine powder that passes through 200 mesh sieve for use;

[0011] (3) Preparation of nano-diaphragm powder: After mixing the low-melting-point electrolyte and MgO in proportion, melt them at 300°C to 450°C under inert gas, crush them into particles with a particle size of less than 10 μm, and dry them at 150°C to 200°C under inert gas;

[0012] (4) Pour the heating powder prepared in (1) into the mold frame and flatten it, then pour the positive electrode material prepared in (2) into the mold frame and flatten it, and finally add the nano-diaphragm powder prepared in (3) and flatten it, and finally cover the mold, place it on the press, apply a certain pressure, and press it into the composite sheet.

[0013] Furthermore, the electrolyte material used in the method is subjected to an inert drying treatment before use, with a treatment temperature of 175° C. to 200° C., an atmosphere of nitrogen or argon, and a drying time of more than 24 hours.

[0014] The composite sheet described above can be used to prepare a single cell that can be quickly activated. The single cell includes a current collecting sheet, a high-lithium lithium-boron alloy and the composite sheet described in the present invention, and the current collecting sheet, the high-lithium lithium-boron alloy and the composite sheet are stacked in sequence.

[0015] Furthermore, the lithium content in the high-lithium lithium-boron alloy is greater than 64%.

[0016] Furthermore, the current collecting sheet is made of 316 stainless steel with a thickness of 0.01 mm.

[0017] The working principle of the present invention is:

[0018] a) High burning rate heating powder technology

[0019] The heating powder of the thermal battery of the present invention mainly includes micro-nano Fe powder and KClO4. In order to increase the burning rate of the heating powder, the weight ratio of micro-nano iron powder and potassium perchlorate is limited to 70-90:10-25. At this ratio, compared with the heating plate of conventional technology, the present invention can increase the average burning speed from the conventional 18cm / s to 25cm / s, shortening the combustion time of the heating plate; and the average calorific value is increased from the conventional 1300J / g to 1350J / g.

[0020] b) Micro-nano low melting point electrolyte technology

[0021] The higher the melting point of a thermal battery electrolyte, the more heat is required to melt it. The most widely used LiCl-KCl (binary electrolyte) and LiF-LiCl-LiBr (ternary all-lithium electrolyte) in current engineering applications have relatively high melting points of 352°C and 436°C, respectively. These relatively high melting points hinder the rapid activation of thermal batteries. Therefore, the present invention utilizes a low-melting-point electrolyte, LiBr-KBr-CsBr, with a melting point of only 230°C. This significantly reduces the heat required to melt the electrolyte and accelerates thermal battery activation. Furthermore, by miniaturizing the separator particle size, the thermal battery activation time can be shortened.

[0022] c) High thermal conductivity cathode technology

[0023] When the positive and negative electrodes of a thermal battery participate in an electrode reaction, the greater the discharge current density, the faster the required ion migration rate. If the ion migration rate cannot keep up with the electrode reaction rate, severe concentration polarization will occur, increasing the battery's polarization internal resistance and causing the surface external voltage to be too low, ultimately affecting the battery's electrical performance. By adding a certain proportion of a new conductive agent to the positive electrode material, the high thermal conductivity graphene material has better thermal and electrical conductivity than conventional graphite conductive agents. After mixing, the graphene is evenly distributed on the surface of the disulfide material. The use of this new conductive agent can enhance the thermal and electrical conductivity of the electrode, reduce battery polarization, and shorten the battery activation time.

[0024] The beneficial technical effects of the present invention are:

[0025] 1. The composite sheet prepared by the method of the present invention is used to prepare thermal battery cells, which give full play to the advantages of their respective raw materials, can meet the requirements of rapid activation, and have the advantages of good electrochemical performance and strong stability, good conductivity, formability, high calorific value, long storage time, rapid activation, high output density current, strong resistance to harsh environments, and high safety;

[0026] 2. The thermal battery cell of the present invention has high thermal conductivity (to avoid an increase in internal resistance during the discharge process), which is conducive to rapid activation; the electrolyte has a low melting point, which minimizes the heat input required from the heating plate, can shorten the activation time of the thermal battery, and is a fast-activation single cell.

[0027] 3. The single cell of the present invention adopts 0.01mm ultra-thin current collector and high-lithium lithium-boron alloy lithium, which reduces the weight of the battery and improves the output specific energy of the battery; at the same time, the use of ultra-thin current collector and high-lithium lithium-boron alloy lithium is conducive to shortening the activation time of the thermal battery;

[0028] The invention has a simple preparation process, strong operability, does not require the introduction of high-tech or large-scale equipment, and is conducive to large-scale production. The new fast-activation single cell battery shortens the activation time by more than 50% compared with conventional single cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 : Schematic diagram of thermal battery activation;

[0030] Figure 2 : Comparison of activation time of the fast-activated single cell and conventional single cell described in Example 1, (1# conventional single cell, 2# low-melting-point micro-nano diaphragm, 3# low-melting-point micro-nano diaphragm + fast heating sheet, 4# low-melting-point micro-nano diaphragm + fast heating sheet + thin current collector, 5# low-melting-point micro-nano diaphragm + high-burning-rate heating sheet + thin current collector + high-thermal-conductivity positive electrode sheet);

[0031] Figure 3 This is a discharge diagram of a Φ18mm*30mm unit cell assembled from the fast-activated single cell described in Example 1; Figure b is an enlarged view of the period 0 to 1s in Figure a. DETAILED DESCRIPTION

[0032] The following is further described in detail through specific embodiments. The inert gases described in the present invention are argon or nitrogen.

[0033] The parameters of the high thermal conductivity graphene used in the present invention are shown in Table 1 below:

[0034] Table 1

[0035] project parameter project parameter Appearance Gray-black powder Moisture content ≤2％ Bulk density 0.01~0.02g / ml Specific surface area <![CDATA[50~200m 2 / h]]> <![CDATA[Particle size D 50 > 7~12μm Powder Chip Resistors 9.2mΩ·cm <![CDATA[Particle size D 50 > 11~15μm thickness 1st to 3rd floor Single layer rate ＞80％ Diameter-to-thickness ratio Average 9500 Carbon content About 98%

[0036] Example 1: A composite sheet and a method for preparing a fast-activation single cell battery using the composite sheet, comprising the following steps:

[0037] 1. Preparation of thermal battery composite sheets

[0038] (1) Preparation of heating powder: Mix micro-nano iron powder and potassium perchlorate in a weight ratio of 70:18 for later use;

[0039] (2) Preparation of positive electrode materials: NiS2 was calcined at 450℃ in an inert gas atmosphere for more than 4h, and then the calcined NiS2 was crushed and sieved, leaving 200-300 mesh NiS2 powder, and then the electrolyte KCl-LiCl was added and mixed evenly, and then the adsorbent MgO was added and mixed evenly, and finally the high thermal conductivity graphene was added and mixed evenly, and then dried at 170℃ under an inert gas atmosphere, and then crushed and sieved to obtain fine powder that passed a 200 mesh sieve, and sealed and stored for later use;

[0040] The material weight ratio is NiS2: electrolyte: adsorbent: high thermal conductivity graphene = 73:7:5:15;

[0041] (3) Preparation of nano-diaphragm powder: low melting point electrolyte LiBr–KBr–CsBr and MgO were mixed in a gravity ratio of 60:40, melted at 450°C under inert gas, and then crushed into particles with a particle size of less than 10 μm, and then dried at 180°C under inert gas;

[0042] (4) Pour the heating powder prepared in (1) into the mold frame and flatten it, then pour the positive electrode material prepared in (2) into the mold frame and flatten it, and finally add the nano-diaphragm powder prepared in (3) and flatten it, and finally cover the mold, place it on the press, apply a certain pressure, and press it into the composite sheet.

[0043] The pressure applied during tableting is adjusted according to the performance of the press used and the instructions for use according to conventional operations in this field. For example, a 25-ton press is used in production, and when the composite tablets of this scheme are pressed, the pressure is approximately 35KN.

[0044] 2. Preparation of fast-activated single cell batteries

[0045] The 0.01mm stainless steel ultra-thin current collector, the 0.1mm Li64 high-lithium lithium-boron alloy and the composite sheet prepared in the above step 1 are stacked in sequence to form a fast-activation single cell.

[0046] Example 2, a method for preparing a composite sheet, comprising the following steps:

[0047] (1) Preparation of heating powder: Mix micro-nano iron powder and potassium perchlorate in a weight ratio of 82:18 and set aside;

[0048] (2) Preparation of positive electrode materials: CoS2 was calcined at 450℃ in an inert gas atmosphere for more than 4h, and then the calcined CoS2 was crushed and sieved, leaving 200-300 mesh CoS2 powder, and then the electrolyte KCl-LiCl was added and mixed evenly, and then the adsorbent MgO was added and mixed evenly, and finally the high thermal conductivity graphene was added and mixed evenly, and then dried at 170℃ under an inert gas atmosphere, and then crushed and sieved to obtain the fine powder that passed the 200 mesh sieve, and sealed and stored for later use;

[0049] The material weight ratio is CoS2: electrolyte: adsorbent: high thermal conductivity graphene = 85:5:10:7;

[0050] (3) Preparation of nano-diaphragm powder: low melting point electrolyte LiBr–KBr–CsBr and MgO were mixed in a gravity ratio of 60:40, melted at 450°C under inert gas, and then crushed into particles with a particle size of less than 10 μm, and then dried at 180°C under inert gas;

[0051] (4) Pour the heating powder prepared in (1) into the mold frame and flatten it, then pour the positive electrode material prepared in (2) into the mold frame and flatten it, and finally add the nano-diaphragm powder prepared in (3) and flatten it, and finally cover the mold, place it on the press, apply a certain pressure, and press it into the composite sheet.

[0052] Example 3, a method for preparing a composite sheet, comprising the following steps:

[0053] (1) Preparation of heating powder: Mix micro-nano iron powder and potassium perchlorate in a weight ratio of 83:17 for later use;

[0054] (2) Preparation of positive electrode materials: NiS2 was calcined at 450℃ in an inert gas atmosphere for more than 4h, and then the calcined NiS2 was crushed and sieved, leaving 200-300 mesh NiS2 powder, and then the electrolyte KCl-LiCl was added and mixed evenly, and then the adsorbent Al2O3 was added and mixed evenly, and finally the high thermal conductivity graphene was added and mixed evenly, and then dried at 170℃ under an inert gas atmosphere, and then crushed and sieved to obtain fine powder that passed a 200 mesh sieve, and sealed and stored for later use;

[0055] The material weight ratio is NiS2: electrolyte: adsorbent: high thermal conductivity graphene = 65:10:10:15;

[0056] (3) Preparation of nano-diaphragm powder: low melting point electrolyte LiBr–KBr–CsBr and MgO were mixed in a 50:50 gravity ratio, melted at 450°C under inert gas, and then crushed into particles with a particle size of less than 10 μm, and then dried at 180°C under inert gas;

[0057] (4) Pour the heating powder prepared in (1) into the mold frame and flatten it, then pour the positive electrode material prepared in (2) into the mold frame and flatten it, and finally add the nano-diaphragm powder prepared in (3) and flatten it, and finally cover the mold, place it on the press, apply a certain pressure, and press it into the composite sheet.

[0058] Example 4, a method for preparing a composite sheet, comprising the following steps:

[0059] (1) Preparation of heating powder: Mix micro-nano iron powder and potassium perchlorate in a weight ratio of 84:16 for later use;

[0060] (2) Preparation of positive electrode materials: CoS2 was calcined at 450℃ in an inert gas atmosphere for more than 4h, and then the calcined CoS2 was crushed and sieved, leaving 200-300 mesh CoS2 powder, and then the electrolyte KCl-LiCl was added and mixed evenly, and then the adsorbent Al2O3 was added and mixed evenly, and finally the high thermal conductivity graphene was added and mixed evenly, and then dried at 170℃ under an inert gas atmosphere, and then crushed and sieved to obtain fine powder that passed a 200 mesh sieve, and sealed and stored for later use;

[0061] The material weight ratio is CoS2: electrolyte: adsorbent: high thermal conductivity graphene = 73:7:5:15;

[0062] (3) Preparation of nano-diaphragm powder: low melting point electrolyte LiBr–KBr–CsBr and MgO were mixed in a gravity ratio of 60:40, melted at 450°C under inert gas, and then crushed into particles with a particle size of less than 10 μm, and then dried at 180°C under inert gas;

[0063] (4) Pour the heating powder prepared in (1) into the mold frame and flatten it, then pour the positive electrode material prepared in (2) into the mold frame and flatten it, and finally add the nano-diaphragm powder prepared in (3) and flatten it, and finally cover the mold, place it on the press, apply a certain pressure, and press it into the composite sheet.

[0064] Test example

[0065] Here, according to the material preparation method of Example 1, single cells with a diameter of Φ48mm were prepared. Ten single cells were assembled into a unit battery and the discharge was compared with the unit battery equipped with conventional single cells. Figure 2 For five different unit cells at the same current density of 100mA / cm 2Comparison of the lower discharge activation time, (1# conventional single cell (conventional 0.1mm current collector, Li55 lithium boron alloy, composite sheet (low melting point diaphragm + conventional positive electrode), conventional heating sheet), 2# (conventional 0.1mm current collector, Li55 lithium boron alloy, composite sheet (low melting point micro-nano diaphragm + conventional positive electrode), conventional heating sheet), 3# (conventional 0.1mm current collector, Li55 lithium boron alloy, composite sheet (low melting point micro-nano diaphragm + conventional positive electrode), rapid heating sheet), 4# (thin current collector, Li55 lithium boron alloy, composite sheet (low melting point micro-nano diaphragm + conventional positive electrode), high burning rate heating sheet), 5# low melting point micro-nano diaphragm + rapid heating + thin current collector + high thermal conductivity positive electrode sheet) (0.01mm current collector, Li64 high lithium boron alloy, composite sheet (low melting point micro-nano diaphragm + high thermal conductivity positive electrode material + high burning rate heating sheet)), the assembly steps of the five unit batteries are exactly the same.

[0066] Figure 3 According to the method for preparing a single cell in Example 1, a single cell with a diameter of Φ12 mm was prepared. Three single cells were assembled into a unit cell for electrical activation discharge. The discharge current density was 50 mA / cm 2 Discharge for 2s, then switch to 3300mA / cm 2 , activation time reaches 40ms, and technical indicators reach the domestic leading level.

Claims

1. A composite sheet, characterized in that: The invention comprises heating powder, positive electrode material and nano-diaphragm powder which are stacked and pressed in sequence. The heating powder is a mixture of micro-nano iron powder and potassium perchlorate in a weight ratio of 70-90:10-25. The positive electrode material comprises components and the usage ratio of the components is disulfide: electrolyte: adsorbent: high thermal conductivity graphene = 65-85:5-10:3-10:7-15, and the adsorbent is MgO or Al2O3. The nano-diaphragm powder is prepared by mixing electrolyte and MgO in a ratio of 50-65:35-50, heating and melting, and then preparing particles with a particle size of less than 10 μm. The electrolyte used in the nano-diaphragm is: LiBr-KBr-CsBr.

2. A composite sheet according to claim 1, characterized in that: The disulfide is one of FeS2, CoS2, NiS2, WS2, and MoS2.

3. A composite sheet according to claim 2, characterized in that: The electrolyte used in the positive electrode material is KCl-LiCl.

4. The method for preparing a composite sheet according to any one of claims 1 to 3, wherein: include: (1) Preparation of heating powder: Mix micro-nano iron powder and potassium perchlorate in a uniform weight ratio and set aside; (2) Preparation of positive electrode materials: calcine the disulfide at 450℃~500℃ under inert gas for more than 2h, then crush and sieve the calcined disulfide, retain the disulfide powder of 200-300 mesh, add the electrolyte and mix evenly, then add the adsorbent and mix evenly, finally add the high thermal conductivity graphene and mix evenly, then put it into 150℃~300℃ under inert gas and dry it, then crush and sieve out the fine powder that passes through 200 mesh sieve for use; (3) Preparation of nano-diaphragm powder: After mixing the low-melting-point electrolyte and MgO in proportion, melt them under an inert gas atmosphere at 300°C to 450°C, crush them into particles with a size of less than 10 μm, and dry them under an inert gas atmosphere at 150°C to 200°C. (4) Pour the heating powder prepared in (1) into the mold frame and flatten it, then pour the positive electrode material prepared in (2) into the mold frame and flatten it, and finally add the nano-diaphragm powder prepared in (3) and flatten it, and finally cover the mold, place it on the press, apply a certain pressure, and press it into the composite sheet.

5. The method for preparing a composite sheet according to claim 4, wherein: The electrolyte material used in the method is subjected to an inert drying treatment before use, the treatment temperature is 175° C. to 200° C., the atmosphere is nitrogen or argon, and the drying time is more than 24 hours.

6. A single cell prepared using the composite sheet obtained by the method for preparing a composite sheet as claimed in claim 5.

7. A single battery, characterized in that: The single battery comprises a current collecting sheet, a high-lithium lithium-boron alloy and the composite sheet obtained according to claim 4, and the current collecting sheet, the high-lithium lithium-boron alloy and the composite sheet are stacked in sequence.

8. The single cell according to claim 7, characterized in that: The lithium content in the high-lithium lithium-boron alloy is greater than 64%.

9. The single cell according to claim 8, characterized in that: The current collecting piece is made of 316 stainless steel with a thickness of 0.01 mm.

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