A composite heating sheet and a preparation method thereof

Abstract

The present application discloses a composite heating sheet in the technical field of thermal battery materials, which is composed of a three-in-one composite of a fast-burning heating layer - a slow-release heating layer - a fast-burning heating layer. The composite heating sheet prepared by the present invention is formed by the three-in-one composite of a fast-burning heating layer - a slow-release heating layer - a fast-burning heating layer. The fast-burning heating layers at both ends burn to quickly provide heat inside the battery, melting the separator in the thermal battery monomer to quickly activate the thermal battery; while the slow-release heating layer in the middle slowly releases heat, preventing the heating sheet from releasing too much heat in the early stage and impacting the positive electrode material of the thermal battery, preventing the latter from pyrolyzing, and also maintaining the working characteristics of the slow-release heating powder with high specific energy for a long time.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal battery materials, and particularly relates to a composite heating sheet and a preparation method thereof. Background Art

[0002] A thermal battery is a thermally activated reserve battery. When stored at room temperature, the electrolyte is a non-conductive solid. When in use, an electric igniter or a firing pin mechanism is used to ignite the internal heating agent, so that the electrolyte melts into an ionic conductor and is activated. The storage time is theoretically infinite, and the actual measurable value can reach more than 17 years. Due to its large specific power output, small internal resistance, wide operating temperature range, long storage time, rapid and reliable activation, and no need for maintenance, it has developed into an ideal power source for modern equipment.

[0003] With the continuous expansion of the application fields of thermal batteries, long-working-time thermal batteries are increasingly becoming the development trend of thermal batteries. However, as the working time of thermal batteries extends, the pyrolysis of the positive electrode material of thermal batteries intensifies, resulting in the specific energy of thermal batteries not meeting the requirements. To solve this problem, scientific researchers have developed a slow-release heating powder, which reduces the thermal shock inside the battery by delaying the heat release of the heating powder and improves the specific energy of long-time thermal batteries. However, due to the application of the slow-release heating powder, after the thermal battery is activated, the activation time of the thermal battery is affected because the heat release of the slow-release heating powder is slow, which is not conducive to the rapid response of the thermal battery. Summary of the Invention

[0004] The present invention aims to provide a composite heating sheet and a preparation method thereof to solve the problem in the prior art that the activation time of the battery is affected by the slow-release heating powder, which is not conducive to the rapid response of the thermal battery.

[0005] To solve the above problems, the present invention provides the following technical solution: A composite heating sheet is composed of a three-in-one composite of a fast-burning heating layer - a slow-release heating layer - a fast-burning heating layer.

[0006] A preparation method of a composite heating sheet includes the following steps:

[0007] Step a, preparation of fast-burning heating powder: Mix iron powder a and an oxidant evenly to obtain fast-burning heating powder;

[0008] Step b, preparation of slow-release heating powder: Mix iron powder b, an oxidant and a slow-release agent evenly to obtain slow-release heating powder;

[0009] Step c, preparation of the composite heating sheet: Spread and overlap the fast-burning heating powder, the slow-release heating powder, and the fast-burning heating powder in a mold in sequence, and then press the mold under a press to obtain the composite heating sheet.

[0010] Working principle and beneficial effects of the present invention: The composite heating sheet prepared by the present invention is composed of a combination of a fast-burning heating layer, a slow-release heating layer, and a fast-burning heating layer, that is, it has slow-release heating powder, which has a characteristic of long-time high specific energy due to the excessive thermal shock to the cathode material of the thermal battery, and at the same time, the fast-burning heating layers at both ends burn to quickly provide heat at the moment when the battery is activated, melting the separator in the thermal battery monomer to achieve the effect of quickly activating the thermal battery.

[0011] Further, the iron powder a in step a is one or two of nano iron powder and mesoporous iron powder.

[0012] Further, the oxidant is one or two of KClO4 and LiClO4.

[0013] Further, the mass ratio of the iron powder a and the oxidant in step a is 80 - 83:20 - 17.

[0014] Further, the iron powder b in step b is conventional iron powder.

[0015] Further, the mass ratio of the iron powder b, the oxidant, and the slow-release agent in step b is 83 - 89:16 - 8:1 - 3.

[0016] Further, the slow-release agent in step b is one or more of NaCl, Li2O, and KCl.

[0017] Further, the mass ratio of the fast-burning heating powder, the slow-release heating powder, and the fast-burning heating powder in step c is 1 - 2:6 - 8:1 - 2.

[0018] Further, after each even spreading in step c, cover the pressing mold and rotate it for one week. After the top fast-burning heating powder rotates for one week, place the mold under the press for pressing to obtain the composite heating sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the process flow chart of the preparation of the composite heating sheet of the present invention;

[0020] Figure 2 is the vertical sectional view of the composite heating sheet of the present invention;

[0021] Figure 3 is the discharge curve of the composite heating sheet and the slow-release heating sheet. DETAILED DESCRIPTION OF THE INVENTION

[0022] The following is further detailed through specific embodiments:

[0023] Example: A composite heating sheet, as Figure 2 shown, is composed of a combination of a fast-burning heating layer, a slow-release heating layer, and a fast-burning heating layer.

[0024] The preparation method comprises the following steps:

[0025] Step a: Preparation of the fast-burning heating powder: Nanometer iron powder and LiClO4 are placed in a mixer and mixed in a mass ratio of 88:12. After being mixed evenly, the fast-burning heating powder is obtained.

[0026] Step b: Preparation of the slow-release heating powder: Conventional iron powder, KClO4 and NaCl are placed in a mixer and mixed in a mass ratio of 83:16:1. After being mixed evenly, the slow-release heating powder is obtained.

[0027] Step c: Preparation of the composite heating sheet: The fast-burning heating powder, the slow-release heating powder and the fast-burning heating powder are spread flat and overlapped in the composite heating sheet pressing die in sequence. After each spreading is even, the pressing die is covered and rotated for one week. After the top-layer fast-burning heating powder rotates for one week, the die is placed under a press to apply pressure to obtain the composite heating sheet. The mass ratio of the fast-burning heating powder, the slow-release heating powder and the fast-burning heating powder is 1:8:1.

[0028] Using composite heating sheets and slow-release heating sheets of the same weight, with FeS2 as the positive electrode material, LiCl-KCl as the separator, and LiB as the negative electrode, a thermal battery monomer is prepared, and 87 monomers are connected in series to prepare a unit thermal battery. Figure 3 are the discharge curves of the two heating sheets. As can be seen from the figure, the composite heating sheet quickly establishes a voltage relative to the slow-release heating sheet and has the characteristic of a fast activation time, achieving a fast activation of the thermal battery; at the same time, it maintains the thermal impact of the slow-release heating powder on the positive electrode material of the thermal battery and the characteristic of a long-time high specific energy.

[0029] For those skilled in the art, without departing from the technical concept of the present invention, multiple deformations and improvements can also be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application shall be subject to the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. A composite heating sheet, characterized in that, It is composed of a three-in-one composite of a quick-burning heating layer - a slow-release heating layer - a quick-burning heating layer. The quick-burning heating layer is composed of iron powder a and an oxidant. The iron powder a is one or two of nano iron powder and mesoporous iron powder. The mass ratio of the iron powder a to the oxidant is 80-83:20-17. The slow-release heating layer is composed of iron powder b, an oxidant and a slow-release agent. The iron powder b is conventional iron powder. The slow-release agent is one or more of NaCl, Li2O, and KCl. The oxidant is one or two of KClO4 and LiClO4. The mass ratio of the iron powder b, the oxidant and the slow-release agent is 83-89:16-8:1-3.

2. The preparation method of the composite heating sheet according to claim 1, characterized in that, It includes the following steps: Step a, preparation of quick-burning heating powder: Mix the iron powder a and the oxidant evenly to obtain the quick-burning heating powder; Step b, preparation of slow-release heating powder: Mix the iron powder b, the oxidant and the slow-release agent evenly to obtain the slow-release heating powder; Step c, preparation of the composite heating sheet: Spread and overlap the quick-burning heating powder, the slow-release heating powder, and the quick-burning heating powder in sequence in a mold, and then place the mold under a press to press to obtain the composite heating sheet.

3. The preparation method of the composite heating sheet according to claim 2, characterized in that, In step c, the mass ratio of the quick-burning heating powder, the slow-release heating powder and the quick-burning heating powder is 1-2:6-8:1-2.

4. The preparation method of the composite heating sheet according to claim 3, characterized in that, In step c, after each spreading is even, cover the pressing die and rotate it one week. After the quick-burning heating powder on the top layer rotates one week, place the mold under a press to press to obtain the composite heating sheet.

Images