CN115863583A - A kind of thermal battery sulfide cathode material and preparation method thereof - Google Patents

Abstract

The scheme discloses a sulfide anode material of a thermal battery in the technical field of chemical power thermal batteries, the components of the anode material comprise a conductive agent and sulfide, the conductive agent is a nickel-containing composite conductive agent, the nickel-containing composite conductive agent comprises a first conductor and a second conductor of ternary perchloric acid, and at least metal elements contained in the nickel-containing composite conductive agent and the molar ratio of the metal elements to the sulfide are Ni: k: li = m:58.8:41.2, wherein m =1 to 5. The anode material is applied to a long-time tail-end large-current thermal battery, the no-load voltage is high, and the later-stage load capacity is strong.

Description

A kind of thermal battery sulfide cathode material and preparation method thereof

technical field

The invention belongs to the technical field of chemical power thermal batteries, and in particular relates to a thermal battery sulfide cathode material and a preparation method thereof.

Background technique

Thermal battery is a kind of special chemical power source, which is widely used in aerospace field because of its excellent power output performance and long storage life. Common thermal battery cathode materials (such as sulfides) have high interface resistance at high temperatures, so it is necessary to add ion-conducting agents and electron-conducting agents to improve the interface resistance of the cathode. With the development of remote equipment, the industry has put forward higher requirements for the performance of thermal batteries, such as the initial discharge current is small, the positive electrode material provides a higher voltage in the early stage, no-load in the middle stage, and the positive electrode material has higher ion conductivity in the later stage and electronic conductivity, etc., therefore, cathode materials with high electrical conductivity and high thermal shock resistance have become one of the important development directions of thermal batteries.

The main active material in the current thermal battery cathode material is sulfide. In the current research, due to the high mobility of alkali metal ions and high ion conductivity, it is very suitable for high-power thermal batteries, so the active material and alkali metal are mainly used. Halide molten salt composites are used to build thermal battery cathode materials. For example, CN201910205114.2 reports a high-potential, high-power thermal battery cathode material composed of fluoride, LiF-NaF-LiCl and LiF-KF-LiCl eutectic salts. CN201910304122.2 reports a composite positive electrode material composed of sulfide and potassium-containing electrolyte that reduces self-discharge; CN201110067556.9 reports a positive electrode material composed of nickel chloride positive electrode and alkali metal halide eutectic salt; CN201910411142. x reported a cathode material composed of tungsten-molybdenum sulfide and an alkali metal molten salt ion conductor.

Because sulfide will decompose at high temperature to generate sulfur vapor, resulting in loss of positive electrode capacity or exothermic side reactions, which will cause battery thermal runaway in severe cases, so a certain amount of alkali metal halide molten salt is added to the positive electrode material with sulfide It can reduce the interface resistance and prevent the electrolyte in the separator from diffusing and migrating to the positive electrode. The thermal buffering of alkali metal halide molten salt can effectively reduce the decomposition of sulfide and prolong the working time of the battery. At the same time, the long-term terminal high-current load thermal battery also has the characteristics of small current at the beginning of discharge and large load current at the later stage.

In the current thermal battery cathode material, because alkali metal molten salt is used as the ion conductive agent, in the long-term thermal battery, with the depth of discharge and the heat loss of the thermal battery, the discharge by-products of the positive electrode and the process of the positive electrode will be Increase the internal resistance of the battery, and the voltage is low, so that the battery cannot meet the high current load requirements in the later stage of discharge, resulting in long-term heat. The actual capacity output of sulfide can also reduce the internal resistance of the battery in the later stage and meet the high current load requirements of the battery in the later stage of discharge. It is a technical problem that needs to be focused on in the field of thermal battery technology.

Contents of the invention

The present invention aims to provide a thermal battery sulfide positive electrode material aiming at the problems existing in the prior art.

A thermal battery sulfide positive electrode material in this solution, the components of the positive electrode material include conductive agent and sulfide, the conductive agent is a nickel-containing composite conductive agent, and the nickel-containing composite conductive agent includes the first A quasi-conductor and a second-type conductor of ternary perchlorine, and the nickel-containing composite conductive agent contains at least metal elements and a molar ratio of Ni:Li:K=m:58.8:41.2, wherein m=1-5.

The working principle and beneficial technical effects of this scheme are:

The thermal battery with long-term terminal high-current load has the characteristics of small initial discharge current and large later-stage load current. This invention aims at the characteristics of high heat, easy decomposition of the positive pole, low initial voltage and large later-stage resistance of the long-term terminal high-current load thermal battery. , developed a thermal battery sulfide cathode material.

The nickel-containing composite conductive agent of the present invention contains at least metal elements and the molar ratio (Ni:Li:K) is Ni:Li:K=m:58.8:41.2, m=1-5. When the nickel element ratio m<1, there is little difference in properties from the alkali metal halide electrolyte, and it has little impact on the high current load capacity of the battery in the later stage. When the proportion of nickel element m>5, the viscosity will increase, and when the proportion of nickel element is too large, a muddy melt will be formed. The addition of carbonaceous conductive agent may cause the metal nickel produced by rapid reduction during the preparation of composite conductive agent. Layered settlement makes the composite conductive agent uneven.

1. By introducing the heavy metal element nickel into the molten salt system with fast ion migration speed, the melting point of the molten salt is increased, the thermal impact of the heating material on the positive electrode material at the initial stage of activation is reduced, and the decomposition of the positive active material sulfide is reduced; secondly, by introducing heavy metals The element nickel changes the viscosity of the material, reduces the high-temperature fluidity of the ion-conducting agent, and improves the binding force with the interface of the active material.

2. It is especially important to realize the uniform distribution of metal nickel ions by using the second-type conductor of ternary perchlorochloride, in which chloride ions can solvate heavy metal nickel ions at high temperature, and construct a single-unit voltage-regulating function Contains nickel solvation combination, so in addition to high ion conductivity, the positive electrode material can also provide correction voltage in the initial small current or no-load operation, and use weak electrochemical action or self-discharge effect to produce highly conductive metal nickel, Provide a highly active electronic conductive agent for the later electrochemical process of the battery to achieve a large battery load output in the later period.

3. The nickel-containing composite conductive agent in the present invention has a single voltage boosting function. Since the conductive agent of this solution contains metal nickel ions, metal nickel ions are more likely to accept electrons, so in the initial stage of battery discharge, the nickel-containing composite conductive agent has Boost the voltage function to increase the voltage of the sulfide monomer from about 2V to 2.1-2.6V. At the same time, due to the electrochemical reaction of metal nickel ions at the positive electrode, it can provide metal nickel with high electronic conductivity for the later stage of the battery to carry a greater current density.

Further, the sulfide is selected from FeS ₂ ; CoS ₂ ; NiS ₂ ; F _x Co _y S ₂ , where x+y=1; F _x Co _y N _z S ₂ , where x+y+z=1; WS ₂ ; any one or more combinations of _MoS2 .

Further, the mass ratio of the sulfide is 50%-95%. Preferably 70% to 90%. The remaining components are composite conductive agents, and additional metal conductive agents and carbonaceous conductive agents can also be added. As a preferred solution, if the mass ratio of the active material is greater than 95%, the material has poor formability, low ion conductivity, large internal resistance of the battery, and poor quality consistency. If the mass ratio is lower than 50%, the capacity of the positive electrode material is low, and nickel ions will interfere with the voltage for a long time, so it is not suitable for a long-term terminal high-current load thermal battery.

Further, the first type of conductor is an electronic conductor, including metal conductive agents and non-metallic carbonaceous conductive agents.

Further, the contents of the non-metallic carbon and Ni are both 0.01%-5% of the total mass of the nickel-containing composite conductive agent. Among them, the content of non-metallic carbon is preferably 1% to 3%. The specific content of metallic nickel can be determined by adding carbonaceous conductive agent and reducing time.

Furthermore, the content of the non-metallic carbon is 1%-3% of the total mass of the nickel-containing composite conductive agent.

Further, the metal conductive agent is selected from one or a combination of at least two of gold, silver, platinum, manganese, iron, cobalt, nickel, copper, zinc, lead, tin, indium, antimony, bismuth, etc. Iron, cobalt, nickel, copper, zinc, gold, silver are preferred. Metal conductors are mainly made of highly conductive metals, which can be added physically, or nickel ions in the composite conductive agent can be partially reduced by carbonaceous conductive agents. For example, in the preparation process, a certain carbon material is added to the molten salt, and at high temperature, the carbon reduces nickel-containing ions to obtain metallic nickel.

Further, the non-metallic carbon includes any one or more of carbon nanotubes, carbon nanofibers, graphene, carbon nanowires, Ketjen black, conductive carbon black Super P, porous carbon, fullerene or conductive graphite combination of species.

In order to further improve the overall performance of the positive electrode material, the present application also provides a method for preparing the thermal battery sulfide positive electrode material, comprising the following steps:

S1, sulfide pretreatment

Under the protection of an inert atmosphere, the active material sulfide is subjected to staged high-temperature heat treatment, cooled, and sieved through 80-200 meshes for later use;

S2, preparation of composite conductive agent

(1) Pretreatment: vacuum-dry the raw materials containing Ni ²⁺ , Li ⁺ , K ⁺ cations and Cl ^- anions at high temperature, transfer them into a dry atmosphere, and weigh the corresponding raw materials according to the proportion of cations for later use;

(2) Melting and roasting: Mix the raw materials without Ni evenly, transfer them into a crucible, add Ni-containing raw materials on it, transfer them into a high-temperature furnace, and roast them at a high temperature of 375-500°C for 2-8 hours to make the material form uniformly transparent melt;

(3) Composite carbon material: add 0.01-5% by mass non-metallic carbonaceous conductive agent to the melt at high temperature, mix evenly to form a suspension, and keep it warm for 1min-1h;

(4) Rapid cooling: Pour the obtained high-temperature melt suspension into a special condensation container and spread it out. After cooling, crush and refine the cooled block material, and sieve through 80-200 meshes to obtain a composite conductive agent. ;

S3. High-temperature roasting: mix the active material sulfide and the composite conductive agent in proportion, and the mixing method can be any one of mechanical mixing, point, line, surface, body contact or coating after high temperature melting or A combination of at least two;

S4. Post-processing: the mixed materials in S3 are crushed and sieved through 80-200 meshes to obtain sulfide cathode materials.

Further, the staged high-temperature heat treatment process in S1 is calcination at 80-200°C for 4-8 hours under the condition of using dry inert gas circulation to replace the internal atmosphere, and then heating up to 375-500°C for 2-8 hours.

Further, the vacuum drying temperature in the pretreatment process is 60-300° C., and the drying time is 1-24 hours.

Further, the special condensation container is a container with a heat exchange function at the bottom of the container, and the heat exchange medium includes any one of water with a temperature not higher than 10°C, frozen brine, frozen ethylene glycol, and low-temperature antifreeze containing ethylene glycol. one or more combinations.

Further, the mixing of the active material sulfide and the composite conductive agent in S3 is carried out by ball milling at a speed of 200-1000 r/min by a powder mixer, and after mixing evenly, it is sent to a high-temperature furnace protected by an inert gas for high-temperature roasting. cool down.

Compared with the prior art, the present invention has the following beneficial effects:

1) The present invention prepares thermal battery sulfide positive electrode materials by utilizing the high-temperature solvation of heavy metal Ni ions by Cl ions to achieve uniform distribution of metal nickel ions, and at the same time combines the use of liquefied gas for rapid cooling to achieve rapid shaping of high-temperature molten salts, forming Uniform nickel-containing ion conductive agent. The prepared nickel-containing ion conductive agent has uniform composition and high quality and reliability.

2) Since the thermal battery works at high temperature, physical mixing or high-temperature melting treatment can make the positive electrode and the composite conductive agent form a tight bond during the working process of the thermal battery, and the point-line-surface contact or coating after the high-temperature melting treatment can accelerate battery activation. , to shorten the activation time.

3) The method for preparing the sulfide positive electrode material for thermal batteries does not need to match high-precision sophisticated equipment, the process flow is simple, the efficiency is high, and the cost is low, and it is suitable for large-scale production.

Description of drawings

Fig. 1 is the process flow chart of a kind of thermal battery sulfide cathode material preparation method of the present invention;

Fig. 2 is the schematic diagram of a kind of thermal battery sulfide cathode material of the present invention;

3 is a discharge curve of a thermal battery sulfide positive electrode material in Example 1.

Detailed ways

The specific implementation method is further described in detail below, and the preparation method is shown in Figure 1:

Example 1

1. A method for preparing a thermal battery sulfide cathode material, said method comprising the following steps:

S1, sulfide pretreatment

Under the protection of argon atmosphere, the active material CoS ₂ is subjected to staged high-temperature heat treatment. The staged high-temperature treatment process is to roast at 180°C for 4 hours under the condition of using dry argon circulation to replace the internal atmosphere, and then raise the temperature to 450°C for 8 hours, and then cool it down. Sieve with 200 mesh for later use.

S2, preparation of composite conductive agent

(1) Pretreatment: The raw materials whose chemical composition is Li ₂ NiCl ₄ , LiCl, KCl are vacuum-dried at 180°C for 8 hours at high temperature, transferred into a dry atmosphere, weighed according to the ratio of cations, and the molar ratio of metal cations (Ni ²⁺ : Li ⁺ : K ⁺ ) is 2.5:58.8:41.2 (that is, the molar ratio of Li ₂ NiCl ₄ , LiCl, and KCl raw materials is 2.5:53.8:41.2, and the mass ratio is about 536:2281:3074).

(2) Melting and roasting: Mix the Ni-free raw materials (LiCl and KCl) evenly, transfer them into a crucible, add Ni-containing raw materials (Li ₂ NiCl ₄ ) on it, transfer them into a high-temperature furnace, and heat them at a high temperature of 450°C Baking for 8 hours, the material forms a uniform and transparent melt.

(3) Composite carbon material: Add 0.1% by mass carbon nanotubes to the melt at high temperature, stir and mix evenly for 30 minutes, add 1% by mass carbon nanotubes again, and stir rapidly to form a suspension.

(4) Rapid cooling: Pour the obtained high-temperature suspension into a special stainless steel plate container within 30 seconds and spread it out. The bottom of the stainless steel plate is equipped with a water circulation cooling heat exchanger less than 10°C, which can cool the spread in the stainless steel plate extremely quickly. The high-temperature suspension melt is crushed and refined after cooling, and the composite conductive agent is obtained after sieving with 200 mesh.

S3. High-temperature roasting: mix the active material sulfide and the composite conductive agent in a ratio of 80:20, and use a powder mixer to perform ball milling at a speed of 300r/min. After mixing evenly, send it to a high-temperature furnace protected by inert gas for high temperature. Roasting, the calcination temperature is 400°C, the calcination time is 4h, and the furnace is cooled.

S4, post-processing. The calcined and cooled material is crushed and sieved through 200 mesh to obtain the sulfide cathode material.

The positive electrode material is made of active material 80% cobalt disulfide and 20% nickel-containing composite conductive agent after high-temperature melting and bonding. The nickel-containing composite conductive agent is composed of the first type of conductor carbon nanotubes and reduced nickel powder. The composition of the conductor ternary (Ni-K-Li) perchloride ion conductive agent (Schematic 2), and the molar ratio of metal elements (Ni:K:Li) in the composite conductive agent is 2.5:58.8:41.2, and the ratio of carbon nanotubes is about 1%, and the metal nickel produced by reduction is about 1%. The positive electrode material is applied to a long-term terminal high-current thermal battery with a no-load voltage of 2.32V, as shown in Figure 3.

The present invention also provides the following implementation manners, which achieve basically the same effect as that of Embodiment 1.

Example 2

A method for preparing a thermal battery sulfide cathode material, the method comprising the following steps:

S1, sulfide pretreatment

The active material FeS ₂ was subjected to staged high-temperature heat treatment under the protection of an argon atmosphere. The staged high-temperature treatment process was roasting at 180°C for 4 hours under the condition of using dry argon circulation to replace the internal atmosphere, and then raising the temperature to 450°C for 8 hours. Cool and sieve through 200 mesh for later use.

S2, preparation of composite conductive agent

(1) Pretreatment: The chemical composition is NiCl ₂ , LiCl, KCl raw materials are dried in high temperature vacuum at 180°C for 8 hours, transferred into a dry atmosphere, weighed according to the ratio of cations, the molar ratio of metal cations (Ni ²⁺ : Li ⁺ : K ⁺ ) is 2.5:58.8:41.2 (that is, the molar ratio of NiCl ₂ , LiCl, and KCl raw materials is 2.5:58.8:41.2, and the mass ratio is about 324:2493:3074).

(2) Melting and roasting: Mix the raw materials (LiCl and KCl) without Ni evenly, transfer them into a crucible, add Ni-containing raw materials (NiCl ₂ ) on it, transfer them into a high-temperature furnace, and bake them at a high temperature of 450°C for 8h , so that the material forms a uniform and transparent melt.

(3) Composite carbon material: Add 1% by mass carbon nanotubes to the melt at high temperature, mix evenly to form a suspension, and keep warm for 5 minutes.

(4) Rapid cooling: Pour the obtained high-temperature melt suspension into a special container made of stainless steel plate immediately. The bottom of the stainless steel plate is equipped with a heat exchanger that circulates and cools the freezing liquid mainly composed of water and ethylene glycol, which can cool down extremely quickly. The high-temperature suspension melt spread in the stainless steel plate is crushed and refined after cooling, and the composite conductive agent is obtained after sieving with 200 mesh.

S3. High-temperature roasting: mix the active material sulfide and the composite conductive agent in a ratio of 80:20, and use a powder mixer to perform ball milling at a speed of 300r/min. After mixing evenly, send it to a high-temperature furnace protected by inert gas for high temperature. Roasting, cooling with the furnace.

S4. Post-processing: crush the calcined and cooled material, and sieve through 200 mesh to obtain the sulfide positive electrode material.

Example 3

1. A method for preparing a thermal battery sulfide cathode material, said method comprising the following steps:

S1, sulfide pretreatment

The active materials FeS ₂ and CoS ₂ were respectively subjected to segmental high-temperature heat treatment under the protection of argon atmosphere. The segmental high-temperature treatment process was roasting at 180°C for 5 hours under the condition of using dry argon circulation to replace the internal atmosphere, and then raising the temperature to 440°C for high-temperature roasting 12h. Cool and sieve through 200 mesh for later use.

S2, preparation of composite conductive agent

(1) Pretreatment: The chemical composition is NiCl ₂ , LiCl, and KCl-LiCl eutectic raw materials are dried at 180°C for 8 hours in high temperature vacuum, transferred into a dry atmosphere, weighed according to the proportion of cations, and the molar ratio of metal cations (Ni ^{2 +} : Li ⁺ : K ⁺ ) is 2.5:58.8:41.2 (that is, the molar ratio of NiCl ₂ , LiCl, and LiCl-KCl eutectic materials is 2.5:17.6:41.2, and the mass ratio is about 324:746:4820).

(2) Melting and roasting: Mix the Ni-free raw material (LiCl and LiCl-KCl eutectic) evenly, transfer it into a crucible, add Ni-containing raw material (NiCl ₂ ) on it, transfer it into a high-temperature furnace, and heat it at 480°C Roasting at high temperature for 8 hours at high temperature makes the material form a uniform and transparent melt.

(3) Composite carbon material: Add 1% by mass carbon nanotubes to the melt at high temperature, mix evenly to form a suspension, and keep warm for 2 minutes.

(4) Rapid cooling: Pour the obtained high-temperature melt suspension into a special container made of stainless steel plate immediately. The bottom of the stainless steel plate is equipped with a heat exchanger cooled by -5°C frozen brine circulation, which can cool the spread in the stainless steel plate extremely quickly. The high-temperature suspension melt is crushed and refined after cooling, and the composite conductive agent is obtained after sieving with 200 mesh.

S3. High-temperature roasting: mix the active material FeS ₂ , CoS ₂ and the composite conductive agent in a ratio of 40:40:20, and use a powder mixer to perform ball milling at a speed of 300r/min. Carry out high-temperature roasting in a high-temperature furnace and cool with the furnace.

S4. Post-processing: crush the calcined and cooled material, and sieve through 200 mesh to obtain the sulfide positive electrode material.

The positive electrode material of this scheme is made of active material 40% cobalt disulfide, 40% iron disulfide and 20% nickel-containing composite conductive agent through high-temperature melting and bonding. The nickel-containing composite conductive agent is composed of the first type of conductor carbon nanotube and It is composed of reduced nickel powder electronic conductive agent and the second type of conductor ternary (Ni-K-Li) perchloride ion conductive agent, and the molar ratio of metal elements (Ni:K:Li) in the composite conductive agent is 3:58.8:41.2, The proportion of carbon nanotubes is about 1%, and the reduction produces about 1% of metallic nickel. The positive electrode material is applied to a long-term terminal high-current thermal battery, and the no-load voltage is 2.34V.

Example 4

The difference between this scheme and Example 1 is that the positive electrode material in this scheme is composed of 75% nickel disulfide active material, 18% nickel-containing composite conductive agent, 2% silver powder and 5% graphite powder through high temperature melting and bonding , the nickel-containing composite conductive agent is composed of the first type of conductive carbon nanotubes and the reduced nickel powder electronic conductive agent and the second type of conductive ternary (Ni-K-Li) perchloride ion conductive agent, and the metal element mole in the composite conductive agent The ratio (Ni:K:Li) is 2.5:58.8:41.2, the ratio of carbon nanotubes is about 1%, and the metal nickel produced by reduction is about 1%. The positive electrode material is applied to a long-term terminal high-current thermal battery, and the no-load voltage is 2.30V.

Example 5

The difference between this scheme and Example 1 is that the positive electrode material in this scheme is made of 78% iron disulfide as the active material, 20% nickel-containing composite conductive agent and 2% silver powder through high-temperature melting and bonding, and the nickel-containing composite conductive agent It is composed of the first type of conductor carbon nanotubes, the reduced nickel powder electronic conductive agent and the second type of conductor ternary (Ni-K-Li) perchloride ion conductive agent, and the molar ratio of metal elements in the composite conductive agent (Ni: K: Li) is 4:58.8:41.2, the proportion of carbon nanotubes is about 1%, and the metal nickel produced by reduction is about 2%. The positive electrode material is applied to a long-term terminal high-current thermal battery, and the no-load voltage is 2.36V.

Claims (13)

1. A sulfide positive electrode material of a thermal battery, the components of the positive electrode material comprise a conductive agent and sulfide, and the sulfide positive electrode material is characterized in that: the conductive agent is a nickel-containing composite conductive agent, the nickel-containing composite conductive agent comprises a first conductor and a second conductor of ternary perchloric acid, and at least metal elements contained in the nickel-containing composite conductive agent and the molar ratio of the metal elements to the metal elements is Ni: li: k = m:58.8:41.2, wherein m =1 to 5.

2. A thermal battery positive sulfide cell according to claim 1A pole material characterized by: the sulfide is selected from FeS ₂ ；CoS ₂ ；NiS ₂ ；Fe _x Co _y S ₂ Wherein x + y =1; fe _x Co _y Ni _z S ₂ Wherein x + y + z =1; WS (WS) ₂ ；MoS ₂ Any one or a combination of more of them.

3. The sulfide positive electrode material for the thermal battery according to claim 1, wherein: the mass ratio of the sulfide is 50-95%.

4. The sulfide positive electrode material for the thermal battery according to claim 1, wherein: the first type of conductor is an electronic conductor and comprises a metal conductive agent and a non-metal carbonaceous conductive agent.

5. The sulfide positive electrode material for a thermal battery according to claim 4, wherein: the content of the nonmetal carbon and the Ni is 0.01 to 5 percent of the total mass of the nickel-containing composite conductive agent.

6. The sulfide positive electrode material for a thermal battery according to claim 5, wherein: the content of the non-metal carbon is 1-3% of the total mass of the nickel-containing composite conductive agent.

7. The sulfide positive electrode material for a thermal battery according to claim 4, wherein: the metal conductive agent is selected from one or a combination of at least two of gold, silver, platinum, manganese, iron, cobalt, nickel, copper, zinc, lead, tin, indium, antimony, bismuth and the like.

8. The sulfide positive electrode material for a thermal battery according to claim 4, wherein: the nonmetal carbon comprises any one or combination of more of carbon nano tubes, carbon nano fibers, graphene, carbon nano wires, ketjen black, conductive carbon black Super P, porous carbon, fullerene or conductive graphite.

9. The method for preparing the sulfide positive electrode material of the thermal battery according to claim 6, wherein the method comprises the following steps: the method comprises the following steps:

s1, sulfide pretreatment

Carrying out segmented high-temperature heat treatment on the active substance sulfide under the protection of inert atmosphere, cooling, and screening by 80-200 meshes for later use;

s2, preparation of composite conductive agent

(1) Pretreatment: will contain Ni ²⁺ ，Li ⁺ ，K ⁺ Cation and Cl ^- Carrying out high-temperature vacuum drying on the anion raw materials, transferring the anion raw materials into a drying atmosphere, and weighing the corresponding raw materials according to the cation proportion for later use;

(2) Melting and roasting: uniformly mixing the raw materials without Ni, transferring the mixture into a crucible, adding the raw materials containing Ni on the crucible, transferring the mixture into a high-temperature furnace, and roasting the mixture at the temperature of 375-500 ℃ for 2-8 hours to form uniform and transparent melt;

(3) Composite carbon material: adding 0.01-5% of non-metal carbonaceous conductive agent by mass into the melt at high temperature, uniformly mixing to form suspension, and preserving heat for 1 min-1 h;

(4) And (3) quick cooling: pouring the obtained high-temperature melt suspension into a special condensation container to spread, cooling, crushing and refining the cooled block materials, and sieving by 80-200 meshes to obtain the composite conductive agent;

s3, preparing powder and mixing: preparing active substance sulfide and composite conductive agent into powder according to a proportion, and mixing, wherein the mixing mode can be any one or the combination of at least two of mechanical mixing, point, line, surface, body contact or coating after high-temperature melting;

s4, post-processing: and (4) crushing the mixed material in the step (S3), and screening by 80-200 meshes to obtain the sulfide cathode material.

10. The method for preparing a sulfide positive electrode material of a thermal battery according to claim 9, wherein: the step of the step-by-step high-temperature heat treatment in the step S1 is to roast for 4 to 8 hours at the temperature of 80 to 200 ℃ under the condition of circularly replacing the internal atmosphere by dry inert gas, and then to roast for 2 to 8 hours at the temperature of 375 to 500 ℃.

11. The method for preparing a sulfide positive electrode material of a thermal battery according to claim 9, wherein: the vacuum drying temperature in the pretreatment process is 60-300 ℃, and the drying time is 1-24 h.

12. The method for preparing a sulfide positive electrode material of a thermal battery according to claim 9, wherein: the special condensation container is a container with a heat exchange function at the bottom of the container, and the heat exchange medium comprises any one or a combination of water with the temperature not higher than 10 ℃, frozen brine, frozen methanol, frozen ethanol, frozen glycol and low-temperature antifreeze solution containing glycol.

13. The method for preparing a sulfide positive electrode material of a thermal battery according to claim 9, wherein: and (4) mixing the active substance sulfide and the composite conductive agent in the step (S3) by adopting a powder mixer to perform ball milling and mixing at the speed of 200-1000 r/min, uniformly mixing, then sending into a high-temperature furnace protected by inert gas to perform high-temperature roasting, and cooling along with the furnace.

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