Preparation method of negative electrode and collector integrated structure of lithium-series thermal battery

Abstract

The invention relates to a preparation method of an integrated structure of a negative electrode and a current collector of a lithium-series thermal battery, and solves the problem that a pressed lithium-boron alloy sheet falls off from a choke ring. Before production, the lithium-boron alloy is subjected to surface pretreatment, an oxide layer and an oil seal layer on the surface are removed, and the surface roughness is increased, during preparation, a choke ring, a lithium-boron alloy sheet and a collector sheet are sequentially placed in a mold, it is guaranteed that the three sheets are coaxial, a pressing mold is covered, the lithium-boron alloy and the collector sheet are pressed and formed through a pressing method, and after forming, the lithium-boron alloy is obtained. The lithium-boron alloy sheet is embedded into the choke ring, and the choke ring is fully bonded with the lithium-boron alloy sheet and the collector sheet. Welding and edge wrapping are not needed in the pressing process, pressing is carried out only after automatic assembly of a mechanical arm, and technological automation of negative plate preparation is achieved more easily.

Description

Technical Field

[0001] This invention belongs to the field of pyrotechnics and power supply technology, specifically relating to a method for preparing an integrated structure of a negative electrode and current collector for a lithium-based thermal battery. Background Technology

[0002] With the development of automation in lithium-based thermal battery technology and the requirement for high energy density, the single cell of thermal battery has gradually shifted from integrated pressing of positive electrode layer, electrolyte layer and negative electrode layer to single-layer pressing. At this time, it is difficult to form the lithium boron alloy sheet, current blocking ring and current collector of the negative electrode layer by means of tolerance matching, or they are easy to fall off and fall apart after forming.

[0003] There are two existing methods for fabricating the integrated negative electrode and current collector structure of lithium-ion thermal batteries: One method involves concentrically spot welding a nickel square-hole mesh to the current collector using energy storage welding, and then pressing it together with a lithium-boron alloy and a baffle ring using a press. This method utilizes the ductility of the lithium-boron alloy, achieving a good bond between the nickel mesh and the alloy with relatively low pressure. The second method involves wrapping the lithium-boron alloy with a cup-shaped current collector to form the negative electrode. While both methods can solve the problem of the lithium-boron alloy sheet easily detaching from the baffle ring, the addition of a nickel mesh layer or edge wrapping results in a thicker negative electrode. When multiple individual cells are stacked together in parallel or series, the stack height becomes significantly higher, which is detrimental to the high energy-to-volume ratio requirements of current weapon systems. Furthermore, the complexity of the process increases the difficulty of automating the process. Summary of the Invention

[0004] This invention provides a method for preparing an integrated structure of negative electrode and current collector for lithium-based thermal batteries. It solves the problems of lithium-boron alloy sheets detaching from the current-blocking ring after pressing, and the issue of increased negative electrode thickness affecting the overall battery height due to the preparation method. Furthermore, the simpler process allows for easier automation.

[0005] This invention is achieved through the following technical solutions: A method for fabricating an integrated negative electrode and current collector structure for a lithium-based thermal battery involves pre-treating the surface of a lithium-boron alloy before production to remove the oxide layer and oil seal layer, while also increasing surface roughness. During fabrication, a flow-blocking ring, a lithium-boron alloy sheet, and a current collector are sequentially placed in a mold, ensuring they are coaxial. A pressure mold is then closed, and a suitable pressing method is used to press the lithium-boron alloy and current collector into shape. After molding, the flow-blocking ring is fully bonded to the lithium-boron alloy sheet and the current collector.

[0006] The flow-blocking ring is made of asbestos paper or asbestos paper compound, and its thickness should be the same as that of the lithium boron alloy sheet, and its inner diameter should be the same as that of the lithium boron alloy sheet. It is matched with the lithium boron alloy sheet by means of tolerance.

[0007] The lithium-boron alloy sheet is stamped from lithium-boron alloy strip and features high discharge power, rapid activation, and long storage time, making it an important negative electrode material for lithium-based thermal batteries.

[0008] The current collector and the current blocking ring have the same outer diameter. They are usually placed between individual cells. They not only serve as current collectors, but also effectively separate the heating element from the negative electrode of the adjacent individual cell, preventing the negative electrode from coming into contact with an open flame after the battery is activated, thus avoiding potential safety hazards caused by the battery being heated.

[0009] The pretreatment method involves grinding the surface of the lithium-boron alloy with a grinding wheel equipped with a scouring pad before production. The purpose is to remove the oxide layer and oil seal layer on the surface of the lithium-boron alloy, while increasing the surface roughness of the lithium-boron alloy, which is more conducive to the adhesion of the lithium-boron alloy to the current collector.

[0010] The pressing method described above involves pressing the flow-blocking ring, lithium-boron alloy sheet, and current collector under high pressure (e.g., 700KN~800KN for a Φ55 lithium-boron sheet). The good ductility of the lithium-boron alloy is utilized to achieve dimensional fit with the flow-blocking ring and adhesion to the surface of the current collector under high pressure.

[0011] The beneficial effects of this invention are: 1. This invention is a method for preparing an integrated structure of negative electrode and current collector of a lithium-based thermal battery. Before production, the surface of the lithium-boron alloy is polished to increase the surface roughness, which is beneficial to the bonding of the lithium-boron alloy and the current collector.

[0012] 2. This invention uses high pressure to press the lithium boron alloy, the flow-blocking ring, and the current collector. Taking advantage of the good ductility of the lithium boron alloy, it can better bond with the flow-blocking ring and the current collector under high pressure.

[0013] 3. While ensuring the tight integration of the negative electrode and the current collector integrated structure, this invention can also guarantee the minimum design thickness of the single cell, thus minimizing the thermal stress or excessive heat caused by the negative electrode preparation method.

[0014] 4. The pressing process of this invention does not require welding or edge wrapping. It only requires automatic assembly by a robotic arm and pressing, which makes it easier to automate the process of negative electrode preparation. Attached Figure Description

[0015] Figure 1 It is a structure that integrates the negative electrode and current collector of a thermal battery. Detailed Implementation

[0016] To further understand the content, features, and effects of this invention, the following embodiments are provided, and detailed descriptions are given in conjunction with the accompanying drawings: Reference Figure 1A method for preparing an integrated structure of negative electrode and current collector of a lithium-based thermal battery involves pre-treating the surface of the lithium-boron alloy sheet 2 using a grinding wheel before production. The pre-treatment method is to lightly grind the sheet to remove surface oil stains and increase surface roughness, which facilitates bonding with the current collector under pressure.

[0017] A method for preparing an integrated structure of negative electrode and current collector for lithium-based thermal batteries involves pressing with a large pressure (e.g., 700KN~800KN for Φ55 lithium boron sheets). The good ductility of the lithium boron alloy allows it to bond well with the current blocking ring 1 and the current collector 3.

[0018] A method for fabricating an integrated negative electrode and current collector structure for a lithium-based thermal battery is disclosed. This method involves pre-treating a lithium-boron alloy sheet and applying increased pressure, utilizing the inherent physical properties of lithium-boron. It eliminates the need for bonding with a porous nickel mesh and for wrapping the edges of the lithium-boron alloy sheet with a current collector to form an integrated structure. This solves the problem of increased negative electrode thickness affecting the overall battery height caused by the fabrication method. Furthermore, the method is simpler and easier to automate. The described embodiments are only a part of the invention, not all. This invention is applicable to all four-in-one, three-in-one, and two-in-one lithium-based single-cell batteries that require the negative electrode surface to be integrally pressed with the current collector. Without departing from the principles of this invention, the pressure can be adjusted according to the size of the single-cell battery; all such adjustments fall within the scope of this invention.

Claims

1. A method for preparing an integrated structure of negative electrode and current collector for a lithium-based thermal battery, characterized in that: Before production, the lithium-boron alloy undergoes surface pretreatment to remove the oxide layer and oil seal layer, increasing surface roughness. During preparation, a flow-blocking ring, a lithium-boron alloy sheet, and a current collector are placed sequentially in the mold, ensuring that the three are coaxial. The mold is then closed, and the lithium-boron alloy and current collector are pressed into shape using a pressing method. After forming, the lithium-boron alloy sheet is embedded in the flow-blocking ring, and the flow-blocking ring is fully bonded to the lithium-boron alloy sheet and the current collector.

2. The method for preparing a lithium-based thermal battery anode and current collector integrated structure according to claim 1, characterized in that: The flow-blocking ring is made of asbestos paper or asbestos paper compound, and its thickness should be the same as that of the lithium boron alloy sheet, and its inner diameter should be the same as that of the lithium boron alloy sheet. It is matched with the lithium boron alloy sheet by means of tolerance.

3. The method for preparing a lithium-based thermal battery anode and current collector integrated structure according to claim 1, characterized in that: The lithium-boron alloy sheet is stamped from a lithium-boron alloy strip.

4. The method for preparing a lithium-based thermal battery anode and current collector integrated structure according to claim 1, characterized in that: The outer diameter of the current collector plate is the same as that of the current blocking ring.

5. The method for preparing an integrated structure of negative electrode and current collector for a lithium-based thermal battery according to claim 1, characterized in that: The surface pretreatment method described above involves grinding the surface of the lithium boron alloy sheet using a grinding wheel equipped with a scouring pad.

6. The method for preparing a lithium-based thermal battery anode and current collector integrated structure according to claim 1, characterized in that: The pressing method involves pressing the flow-blocking ring, lithium-boron alloy sheet, and current collector with a pressure of 700KN to 800KN.

7. The method for preparing an integrated structure of negative electrode and current collector for a lithium-based thermal battery according to claim 1, characterized in that: The method is applicable to all lithium-ion single cells that require the negative electrode surface to be integrally pressed with the current collector, including four-in-one, three-in-one, and two-in-one cells.

Images