Porous composite positive electrode material suitable for lithium primary battery as well as preparation method and application of porous composite positive electrode material

Abstract

The preparation method is innovated according to the pyrolytic reaction characteristics of chromium trioxide, such as a heat absorption phenomenon and an oxygen evolution phenomenon in a pyrolytic process, which bring serious negative effects on the temperature field uniformity and heat balance of a reaction site and further affect the reaction process and phase uniformity of a product; the invention particularly relates to a preparation method and application of a porous composite positive electrode material suitable for a lithium primary battery. And the metal oxide with high heat conductivity coefficient is used for promoting the temperature field uniformity of the reaction and providing a reaction interface of the pyrolytic reaction, so that the phase uniformity of the target product and the consistency of batch performance are improved. Besides, thermal oxygen desorption is a favorable condition for pore forming, the reaction condition and the phase conversion process of the reaction are controlled through a two-step roasting method, and the porous characteristic of the positive electrode material is adjusted, so that the power characteristic and the capacity exerting efficiency of the positive electrode material are further improved, and an effective material modification method and a control method for the batch stability of the material are provided.

Description

Technical Field

[0001] This invention belongs to the field of lithium primary batteries, specifically relating to a porous composite cathode material suitable for lithium primary batteries and its preparation method. Background Technology

[0002] Lithium-ion primary batteries play a crucial role in both military and civilian applications. Currently, the most widely used lithium-ion primary battery systems on the market are lithium manganese dioxide batteries, lithium thionyl chloride batteries, lithium fluoride batteries, and lithium sulfur dioxide batteries, with lithium sulfur batteries and lithium chromium oxide batteries used on a smaller scale. Each of these battery systems has its own advantages and disadvantages. For example, lithium sulfur dioxide and lithium thionyl chloride batteries, which use gaseous and liquid substances as active components respectively, face challenges in packaging and manufacturing. Other battery systems using solid substances or active components also suffer from insufficient energy density, poor power density, low reliability, high cost, or low technological maturity. The recently developed and small-scale tested lithium chromium oxide primary battery system, while theoretically boasting a high energy density (1210Wh / kg) and good power density (sustainable 1C-3C discharge), faces the challenge of simple but difficult-to-control batch stability in cathode material synthesis, resulting in low product yield and insufficient production capacity. Although numerous patents and articles demonstrate modifications to the material during preparation or use to improve the battery system's performance, most do not address modifications based on the material's inherent pyrolysis characteristics, heat, temperature field, or other factors during synthesis. For example, patent CN 113644244 A uses chromium trioxide as a reactant and fluorinated carbon and a highly conductive premix as dopants. The reactants and dopants are sequentially ball-milled and sintered with oxygen to prepare a Cr8O-containing material. 21 Cr2O5, Cr5O 12 Composite cathode materials based on chromium oxides. Chromium trioxide has a melting point of 196℃ at room temperature and pressure. Its low melting point raises concerns about whether material delamination occurs during melting due to interfacial tension and significant density differences between the low-density solid fluorinated carbon, conductive carbon, and the high-density liquid chromium oxide. Furthermore, the large amount of oxygen released during the reaction process may exacerbate surface delamination of the carbon material. While the patent does not address this, it is a real concern. In patent CN118833859 A, the applicant obtained FeS2-doped Cr8O by grinding and then sintering CrO3 and FeS2. 21Composite cathode materials. Although FeS2 possesses electrochemical activity, due to the pyrolysis characteristics of CrO3, a large amount of oxygen is generated at high temperatures, which reacts with FeS2, thus failing to achieve the desired effect. In patent CN 117457848 A, the applicant mixes chromium-based metal oxides with vanadium oxides, conductive agents, and binders in a solvent at a certain ratio, disperses the mixture using ball milling or high-shear dispersion, coats it onto aluminum foil, and dries it to ensure that the vanadium oxides are uniformly distributed among the chromium-based metal oxide nanoparticles, thus obtaining a composite cathode. This patent only optimizes the battery manufacturing process and does not modify the cathode material itself, thus having limited impact on improving the performance of chromium oxide cathode materials. Furthermore, the modification of the porous morphology of the cathode material is crucial for rate discharge performance. In the paper "Design of a Porous Cathode for Ultrahigh Performance of a Li-ion Battery: An Overlooked Pore Distribution," the authors simulated the effects of porosity and pore size on rate discharge performance. The data results show that the porous structure of the cathode material significantly affects rate discharge and capacity. The large-scale, controllable, and stable preparation of this type of material, along with morphology optimization and modification, is key to improving the overall performance of lithium primary batteries. In view of this, this patent application adjusts the temperature field uniformity of the melt based on the reaction characteristics of CrO3 to prepare a porous composite cathode material with uniform phase, batch stability, and controllable pore size, thereby improving the specific capacity and power characteristics of the cathode material. Summary of the Invention

[0003] To address the current situation of insufficient energy density and power density in lithium-ion primary batteries, this invention provides an effective material modification method and batch stability control method based on relatively advantageous cathode materials. This invention addresses the pyrolysis characteristics of CrO3, such as the endothermic and oxygen evolution phenomena that occur during pyrolysis, which severely negatively impact the uniformity of the temperature field and heat balance in the reaction environment. Different reaction processes occur at different temperature zones, negatively affecting the phase purity of the reaction products, and consequently affecting the reaction process and phase uniformity. This invention transforms unfavorable factors into favorable ones by using metal oxides with high thermal conductivity to promote a uniform temperature field and provide a reaction interface for the pyrolysis reaction, improving the phase uniformity and batch performance consistency of the target products. Furthermore, thermal oxygen evolution is a favorable condition for pore formation. Based on the phase transformation process of the reaction, a two-step calcination method is used to adjust the porosity of the cathode material by controlling the reaction conditions, thereby improving the power characteristics and capacity utilization efficiency of the cathode material. Thus, this invention provides an effective material modification method and batch stability control method.

[0004] A method for preparing and applying a porous composite cathode material suitable for lithium primary batteries is described below: (1) Mix CrO3 powder with other metal oxide powders in a certain proportion to form a mixture; the mass ratio of CrO3 powder to other metal oxides is 80% to 95%: 5% to 20%; Other metal oxides are one or more of copper oxide, aluminum oxide, zinc oxide, and magnesium oxide; (2) Under an oxygen or air atmosphere, the mixture obtained in step (1) is subjected to high-temperature calcination and pyrolysis to obtain an ingot-shaped metal oxide composite material; the calcination temperature range is 200℃~300℃, and the calcination time is 2h~24h. (3) The product in step (2) is mechanically pulverized to obtain composite oxide powder material; (4) Under an oxygen or air atmosphere, the powder material obtained in step (3) is subjected to secondary calcination and pyrolysis to obtain a porous target product; The roasting temperature range is 200℃~250℃, and the roasting time is 1h~6h.

[0005] The metal oxide is a high thermal conductivity material with a thermal conductivity of 20-200 W / (m·K), preferably 30-100 W / (m·K), which is much higher than the 1-3 W / (m·K) of CrO3 material.

[0006] The mass ratio of the CrO3 powder to other metal oxide powders is preferably 85%–95%: 5%–15%; more preferably 88%–92%: 8%–12%.

[0007] In step (2), the high-temperature roasting pyrolysis is preferably carried out at a temperature range of 260℃ to 300℃ and for a roasting time of 6h to 12h.

[0008] The particle size distribution of the composite oxide powder material in step (3) is D90: 5um to 25um, preferably 10um to 20um; the mechanical crushing is grinding or ball milling.

[0009] In step (4), the secondary roasting pyrolysis is preferably carried out at a roasting temperature of 220℃ to 250℃ and for a roasting time of 2h to 5h.

[0010] The porous composite cathode material is characterized in that: the porous composite cathode material is a porous high-purity phase Cr8O. 21 Composite materials with other metal oxides are designated as Porous-Cr8O. 21 @MeO.

[0011] The porous composite cathode material is characterized in that: the pores are a porous structure distributed on the surface of the cathode material particles, with pore sizes ranging from macropores to mesopores, preferably from 2 nm to 1 μm, and a specific surface area ranging from 2.5 m² / m³. 2 / g~30 m 2 / g, preferably 10m 2 / g~25 m 2 / g; The porous composite cathode material is used as a cathode active material in lithium primary batteries.

[0012] This invention optimizes the preparation process of chromium-based oxide materials, enabling controllable and stable batch preparation of porous composite cathode materials. This is of great significance for improving the physicochemical properties of cathode materials and the electrical performance of lithium primary batteries, and is also easy to scale up industrially. Specifically, it has the following advantages: This invention improves heat transfer between the inside and outside of the melt by incorporating a metal oxide with high thermal conductivity into the pyrolysis reaction, resulting in a uniform temperature field at the reaction site. This, in turn, allows for uniform control of the phase composition of the reaction products, yielding a pure-phase Cr8O with high specific capacity. 21 The cathode material has a simple preparation process, which is easy to industrialize and solves the problem of uneven phase in the existing preparation process. At the same time, based on the self-pore-forming characteristics and phase transformation characteristics of the reaction, a porous composite cathode material is prepared by combining metal oxide powder with a two-step calcination method. No pore-forming agent is needed, which increases the solid-liquid contact area, i.e., the reaction site area, thereby improving the power characteristics of the cathode material. Furthermore, by adjusting the process conditions, a composite cathode material with controllable pore size can be prepared.

[0013] Furthermore, the electrode reaction of chromium-based oxide cathode materials is a two-stage reaction. The first stage is a lithium intercalation reaction with good kinetic performance, while the second stage is a phase transformation reaction with poor reaction kinetic performance. Moreover, the generated low-conductivity lithium oxide hinders the reaction process, and the heat generated by the reaction is aggravated, affecting the safety performance. This invention combines a metal oxide with a high thermal conductivity in chromium-based oxide, which is beneficial to the conduction of internal heat and avoids the safety hazards of thermal runaway caused by local overheating. Attached Figure Description

[0014] Figure 1 The figure shows the discharge curve of a coin cell (1C@RT). As can be seen from the figure, the specific surface area of ​​the cathode material prepared by the two-step calcination method is increased. The cathode material with further optimized composition and calcination process has a significantly improved specific capacity.

[0015] Figure 2 Example 3 and pure phase Cr8O 21 Diffraction peak comparison diagram. As can be seen from the diagram, the characteristic peaks of the XRD diffraction of the composite oxide cathode material prepared by adding metal oxides are similar to those of the pure phase Cr8O.21 The corresponding characteristic peaks of the diffraction peaks of the phases indicate that the active components in the complex are pure phase components. Detailed Implementation

[0016] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are merely illustrative of the invention and are not intended to limit its scope. Example 1

[0017] 1. Weigh out 25g of powder material according to the weight ratio of CrO3:CuO=95%:5%, mix it evenly and place it in a corundum crucible; 2: The ingot material was kept at 260℃ for 10 hours in an oxygen atmosphere and then naturally cooled before being taken out and ground and crushed. The particle size distribution of the crushed powder was D90: 11.6um. 3: Place the obtained powder material back into the corundum crucible and keep it at 200℃ for 5 hours in an oxygen atmosphere to obtain the positive electrode material powder; 4: The pore size and specific surface area of ​​the cathode material powder after secondary calcination were tested; the results are shown in Table 1; (the final particle size is obtained by crushing after the first calcination in step 2. Secondary calcination only creates pores on the particle surface, and the particle size does not change. The following examples and comparative examples are the same as here.) 5: Button cell fabrication and testing: 1) The obtained cathode material powder, conductive carbon Super-P, and PVDF (polyvinylidene fluoride) were mixed in a mass ratio of 8:1:1. A slurry with a solid content of 55% was prepared using NMP solvent, homogenized, and coated onto aluminum foil. After vacuum drying at 100℃, the cathode material powder had an areal loading of 2.1 mg / cm³. 2 Positive electrode plate; 2) After rolling, the positive electrode sheet is cut into φ12mm round pieces and assembled into CR2032 coin cells in a glove box where the water and oxygen values ​​are both below 0.1ppm. The coin cells are assembled with a lithium negative electrode sheet with a diameter of φ16mm and a thickness of 400um, a PP separator with a thickness of 16um, and a positive electrode sheet of φ12mm. The electrolyte composition is LiFSI:1mol / L; PC:DME=1:1 (v:v), and the electrolyte injection volume is 30uL. 3) The discharge performance of the coin cells was tested, and the specific capacity of the cathode material was evaluated. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1. Example 2

[0018] By changing the secondary calcination conditions while keeping other factors, processes, and conditions consistent with Example 1, cathode materials were prepared and their performance was tested. 1. Weigh out 25g of powder material according to the weight ratio of CrO3:CuO=95%:5%, mix it evenly and place it in a corundum crucible; 2: The ingot material was kept at 260℃ for 10 hours in an oxygen atmosphere and then naturally cooled. It was then removed and ground and crushed. The particle size distribution of the crushed powder was D90: 10.2um. 3: Place the obtained powder material back into the corundum crucible and keep it at 230℃ for 5 hours in an oxygen atmosphere to obtain the positive electrode material powder; 4: The pore size distribution and specific surface area of ​​the cathode material powder after secondary calcination were tested; the results are shown in Table 1. 5: The preparation and testing conditions and processes for the button cells are the same as step 5 in Example 1. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1. Example 3

[0019] By changing the secondary calcination conditions while keeping other factors consistent with Example 1, cathode materials were prepared and their performance was tested. 1. Weigh out 25g of powder material according to the weight ratio of CrO3:CuO=95%:5%, mix it evenly and place it in a corundum crucible; 2: The ingot material was kept at 260℃ for 10 hours in an oxygen atmosphere and then naturally cooled. It was then removed and ground and crushed. The particle size distribution of the crushed powder was D90: 10.7um. 3: The obtained powder material was placed back into the corundum crucible and kept at 250℃ for 5 hours in an oxygen atmosphere to obtain pure phase Cr8O. 21 Composite cathode material with CuO ( Figure 2 ), as a positive electrode material; 4: The pore size distribution and specific surface area of ​​the cathode material powder after secondary calcination were tested; the results are shown in Table 1. 5: The preparation and testing conditions and processes for the button cells are the same as step 5 in Example 1. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1. Example 4

[0020] By changing the proportions of the cathode material components while keeping other factors consistent with Example 3, cathode materials were prepared and their performance was tested. 1. Weigh out 25g of powder material according to the weight ratio of CrO3:CuO=85%:15%, mix it evenly and place it in a corundum crucible; 2: The ingot material was kept at 260℃ for 10 hours in an oxygen atmosphere and then naturally cooled before being taken out and ground and crushed. The particle size distribution of the crushed powder was D90: 12.4um. 3: Place the obtained powder material back into the corundum crucible and keep it at 250°C for 5 hours in an oxygen atmosphere; 4: The pore size distribution and specific surface area of ​​the cathode material powder after secondary calcination were tested; the results are shown in Table 1. 5: The preparation and testing conditions and processes for the button cells are the same as step 5 in Example 1. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1. Example 5

[0021] By changing the composition of the cathode material while keeping other factors consistent with Example 3, a cathode material was prepared and its performance was tested. 1. Weigh out 25g of powder material according to the weight ratio of CrO3:ZnO=95%:5%, mix it evenly and place it in a corundum crucible; 2: The ingot material was kept at 260℃ for 10 hours in an oxygen atmosphere and then naturally cooled before being taken out and ground and crushed. The particle size distribution of the crushed powder was D90: 11.9um. 3: Place the obtained powder material back into the corundum crucible and keep it at 250°C for 5 hours in an oxygen atmosphere; 4: The pore size distribution and specific surface area of ​​the cathode material powder after secondary calcination were tested; the results are shown in Table 1. 5: The preparation and testing conditions and processes for the button cells are the same as step 5 in Example 1. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1. Example 6

[0022] By changing the composition of the cathode material while keeping other factors consistent with Example 3, a cathode material was prepared and its performance was tested. 1. Weigh out 25g of powder material according to the weight ratio of CrO3:MgO=95%:5%, mix it evenly and place it in a corundum crucible; 2: The ingot material was kept at 260℃ for 10 hours in an oxygen atmosphere and then naturally cooled before being taken out and ground and crushed. The particle size distribution of the crushed powder was D90: 12.2um. 3: Place the obtained powder material back into the corundum crucible and keep it at 250°C for 5 hours in an oxygen atmosphere; 4: The pore size distribution and specific surface area of ​​the cathode material powder after secondary calcination were tested; the results are shown in Table 1. 5: The preparation and testing conditions and processes for the button cells are the same as step 5 in Example 1. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1.

[0023] Comparative Example 1 By changing the composition of the cathode material while keeping other factors consistent with Example 3, a cathode material was prepared and its performance was tested. 1. Weigh out 25g of powder material according to the weight ratio of CrO3: Co3O4 = 95%: 5%, mix it evenly and place it in a corundum crucible; 2: The ingot material was kept at 260℃ for 10 hours in an oxygen atmosphere and then naturally cooled before being taken out and ground and crushed. The particle size distribution of the crushed powder was D90: 13.6um. 3: Place the obtained powder material back into the corundum crucible and keep it at 250°C for 5 hours in an oxygen atmosphere; 4: The pore size distribution and specific surface area of ​​the cathode material powder after secondary calcination were tested; the results are shown in Table 1. 5: The preparation and testing conditions and processes for the button cells are the same as step 5 in Example 1. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1.

[0024] Comparative Example 2 By changing the proportions of the cathode material components while keeping other factors consistent with Example 3, cathode materials were prepared and their performance was tested. 1. Weigh out 25g of powder material according to the weight ratio of CrO3:CuO=70%:30%, mix it evenly and place it in a corundum crucible; 2: The ingot material was kept at 260℃ for 10 hours in an oxygen atmosphere and then naturally cooled before being taken out and ground and crushed. The particle size distribution of the crushed powder was D90: 14.1um. 3: Place the obtained powder material back into the corundum crucible and keep it at 250°C for 5 hours in an oxygen atmosphere; 4: The pore size distribution and specific surface area of ​​the cathode material powder after secondary calcination were tested; the results are shown in Table 1. 5: The preparation and testing conditions and processes for the button cells are the same as step 5 in Example 1. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1.

[0025] Comparative Example 3 By changing the proportions of the cathode material components while keeping other factors consistent with Example 3, cathode materials were prepared and their performance was tested. 1. Weigh out 25g of powder material according to the weight ratio of CrO3:CuO=99%:1%, mix it evenly and place it in a corundum crucible; 2: The ingot material was kept at 260℃ for 10 hours in an oxygen atmosphere and then naturally cooled before being taken out and ground and crushed. The particle size distribution of the crushed powder was D90: 11.3um. 3: Place the obtained powder material back into the corundum crucible and keep it at 250°C for 5 hours in an oxygen atmosphere; 4: The pore size distribution and specific surface area of ​​the cathode material powder after secondary calcination were tested; the results are shown in Table 1. 5: The preparation and testing conditions and processes for the button cells are the same as step 5 in Example 1. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1.

[0026] Comparative Example 4 1: Weigh 25g of CrO3 powder and place it in a corundum crucible; 2: The ingot material was kept at 260℃ for 10 hours in an oxygen atmosphere and then naturally cooled before being taken out and ground and crushed. The particle size distribution of the crushed powder was D90: 12.8um. 3: Place the obtained powder material back into the corundum crucible and keep it at 250°C for 5 hours in an oxygen atmosphere; 4: The pore size distribution and specific surface area of ​​the cathode material powder after secondary calcination were tested; the results are shown in Table 1. 5: The preparation and testing conditions and processes for the button cells are the same as step 5 in Example 1. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1.

[0027] Comparative Example 5 1: Weigh 25g of CrO3 powder and place it in a corundum crucible; 2: The ingot material was kept at 320℃ for 10 hours in an oxygen atmosphere and then naturally cooled before being taken out and ground and crushed. The particle size distribution of the crushed powder was D90: 15.1um. 3: Place the obtained powder material back into the corundum crucible and keep it at 250°C for 5 hours in an oxygen atmosphere; 4: The pore size distribution and specific surface area of ​​the cathode material powder after secondary calcination were tested; the results are shown in Table 1. 5: The preparation and testing conditions and processes for the button cells are the same as step 5 in Example 1. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1.

[0028] Comparative Example 6 1: Weigh 25g of CrO3 powder and place it in a corundum crucible; 2: The ingot material was kept at 260℃ for 10 hours in an oxygen atmosphere and then naturally cooled before being taken out and ground and crushed. The particle size distribution of the crushed powder was D90: 12.1um. 3: Place the obtained powder material back into the corundum crucible and keep it at 300℃ for 5 hours in an oxygen atmosphere; 4: The pore size distribution and specific surface area of ​​the cathode material powder after secondary calcination were tested; the results are shown in Table 1. 5: The preparation and testing conditions and processes for the button cells are the same as step 5 in Example 1. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1.

[0029] Comparative Example 7: 1: Weigh 25g of CrO3 powder and place it in a corundum crucible; 2: The ingot material was kept at 260℃ for 10 hours in an oxygen atmosphere and then naturally cooled before being taken out and ground and crushed. The particle size distribution of the crushed powder was D90: 10.6um. 3: The specific surface area of ​​the calcined cathode material powder was tested; the results are shown in Table 1. 4: The preparation and testing conditions and processes for the button cells are the same as in step 5 of Example 1. The results are shown in Table 1 and... Figure 1 As shown in Table 1, discharge was performed at a discharge rate of 1C at room temperature, and the discharge data are shown in Table 1.

[0030] The physicochemical and electrical properties of the obtained cathode material are summarized in Table 1 below: Table 1 Experiment number Cathode material precursor composition Synthesis conditions Particle size distribution Aperture distribution Specific surface area Capacity Example 1 <![CDATA[CrO3:CuO=95%:5%]]> 260℃@10h / 200℃@5h D90: 11.6um 20.4nm-654.5nm <![CDATA[6.1m 2 / g]]> 348.4mAh / g@1C Example 2 <![CDATA[CrO3:CuO=95%:5%]]> 260℃@10h / 230℃@5h D90: 10.2um 46.5nm-867.2nm <![CDATA[8.6m 2 / g]]> 359.6mAh / g@1C Example 3 <![CDATA[CrO3:CuO=95%:5%]]> 260℃@10h / 250℃@5h D90: 10.7um 56.6nm-934.8nm <![CDATA[11.5m 2 / g]]> 397.1mAh / g@1C Example 4 <![CDATA[CrO3:CuO=85%:15%]]> 260℃@10h / 250℃@5h D90: 12.4um 89.9nm-980.3nm <![CDATA[12.4m 2 / g]]> 375.5mAh / g@1C Example 5 <![CDATA[CrO3:ZnO=95%:5%]]> 260℃@10h / 250℃@5h D90: 11.9um 54.6nm-795.3nm <![CDATA[11.9m 2 / g]]> 382.9mAh / g@1C Example 6 <![CDATA[CrO3:MgO=95%:5%]]> 260℃@10h / 250℃@5h D90: 12.2um 52.7nm-894.5nm <![CDATA[12.2m 2 / g]]> 377.6mAh / g@1C Comparative Example 1 <![CDATA[CrO3:Co3O4=95%:5%]]> 260℃@10h / 250℃@5h D90: 13.6um 90.7nm-883.2nm <![CDATA[6.3m 2 / g]]> 340.1mAh / g@1C Comparative Example 2 <![CDATA[CrO3:CuO=70%:30%]]> 260℃@10h / 250℃@5h D90: 14.1um 93.5nm-940.2nm <![CDATA[8.2m 2 / g]]> 325.6mAh / g@1C Comparative Example 3 <![CDATA[CrO3:CuO=99%:1%]]> 260℃@10h / 250℃@5h D90: 11.3um 89.9nm-980.3nm <![CDATA[7.4m 2 / g]]> 333.2mAh / g@1C Comparative Example 4 <![CDATA[CrO3]]> 260℃@10h / 250℃@5h D90: 12.8um 84.2nm-907.5nm <![CDATA[8.4m 2 / g]]> 321.6mAh / g@1C Comparative Example 5 <![CDATA[CrO3]]> 320℃@10h / 250℃@5h D90: 15.1um 90.3nm-772.7nm <![CDATA[8.6m 2 / g]]> 316.7mAh / g@1C Comparative Example 6 <![CDATA[CrO3]]> 260℃@10h / 300℃@5h D90: 12.1um 100.5nm-967.3nm <![CDATA[9.2m 2 / g]]> 311.3mAh / g@1C Comparative Example 7 <![CDATA[CrO3]]> 260℃@10h D90: 10.6um -- <![CDATA[1.7m 2 / g]]> 303.6mAh / g@1C Experimental results analysis: When using CuO, which has high thermal conductivity and active properties, as the composite material, the resulting pure-phase porous cathode material exhibits the highest specific capacity performance. Adjusting the composition, introducing a secondary calcination process, and changing the conditions significantly affect the physicochemical and electrical properties of the cathode material.

Claims

1. A method for preparing and using a porous composite cathode material suitable for use in a lithium primary battery, characterized in that: The preparation process is as follows: (1) CrO3 powder and other metal oxide powder are mixed in a certain proportion to form a mixture; the mass ratio of CrO3 powder to other metal oxides is 80%-95%:5%-20%; The other metal oxides are one or two or more of copper oxide, aluminum oxide, zinc oxide, and magnesium oxide; (2) The mixture obtained in step (1) is subjected to high-temperature calcination pyrolysis under an oxygen or air atmosphere to obtain an ingot-shaped metal oxide composite material; the calcination temperature range is 200-300°C, and the calcination time is 2-16h; (3) The product in step (2) is mechanically pulverized to obtain a composite oxide powder material; (4) The powder material obtained in step (3) is subjected to secondary calcination pyrolysis under an oxygen or air atmosphere to obtain a porous target product; the calcination temperature range is 200-250°C, and the calcination time is 1-6h.

2. The production method according to claim 1, characterized by: The other metal oxides belong to high thermal conductivity materials, and the thermal conductivity of high thermal conductivity metal oxide materials is 20-200 W / (m·K), preferably 30-100 W / (m·K), which is much higher than the 1-3 W / (m·K) of CrO3 materials.

3. The production method according to claim 1, wherein: The mixture of CrO3 powder and other metal oxide powder has a mass ratio of 85%-95%:5%-15%, and more preferably 88%-92%:8%-12%.

4. The production method according to claim 1, wherein: In step (2), the high-temperature calcination pyrolysis has a calcination temperature range of 260-300°C and a calcination time of 6-12h.

5. The production method according to claim 1, wherein: The particle size distribution of the composite oxide powder material in step (3) is D90: 5-25um, preferably 10-20um; and the mechanical pulverization is grinding or ball milling.

6. The production method according to claim 1, wherein: In step (4), the secondary calcination pyrolysis has a calcination temperature range of 220-250°C and a calcination time of 2-5h.

7. The porous composite cathode material obtained by the preparation method according to any one of claims 1-6, characterized in that: The porous composite cathode material is a porous high-purity phase Cr8O 21 The composite material with other metal oxides is denoted as Porous-Cr8O 21 @MeO.

8. The porous composite cathode material of claim 7, wherein: The porous structure is a pore structure distributed on the surface of the positive electrode material particle, and the pore diameter is macropore and mesopore, ranging from 2 nm to 1 um, preferably 50 nm to 1 um; the specific surface area ranges from 2.5 m 2 / g to 30 m 2 / g, preferably 10 m 2 / g to 25 m 2 / g.

9. Use of the porous composite positive electrode material of any one of claims 7-8 as a positive electrode active material in a lithium primary battery.

Images