Carbon fluoride / niobium pentoxide mixed positive electrode, preparation method and application thereof
By developing a composite cathode of fluorinated carbon and niobium pentoxide, the conductivity and thermal conductivity issues of lithium/fluorinated carbon batteries were resolved, improving the rate performance and discharge capacity of the batteries, reducing heat generation, and enhancing safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-11-29
- Publication Date
- 2026-05-29
AI Technical Summary
The poor electrical and thermal conductivity of fluorinated carbon results in poor high-rate discharge capability and high heat generation in lithium/carbon fluoride batteries, which limits their widespread application.
Fluorinated carbon and niobium pentoxide composite cathodes were prepared by ball milling, gas-phase fluorination, and slurry coating. Conductive agents such as single-walled carbon nanotubes, multi-walled carbon nanotubes, or graphene were used to improve conductivity and reduce heat generation.
It improves the rate performance and discharge capacity of lithium/carbon fluoride batteries, reduces battery heat generation, reduces safety hazards, and enhances battery energy performance and lithium-ion diffusion capability.
Smart Images
Figure BDA0005162679790000031 
Figure BDA0005162679790000041 
Figure BDA0005162679790000081
Abstract
Description
Technical Field
[0001] This invention relates to the preparation method and application of a fluorinated carbon / niobium pentoxide hybrid cathode, belonging to the field of lithium / fluorinated carbon batteries. Background Technology
[0002] In recent years, lithium / carbon fluoride batteries have attracted widespread attention in the lithium primary battery field due to their ultra-high theoretical specific energy (2180 Wh / kg). However, due to the poor electrical and thermal conductivity of fluoride itself, lithium-carbon fluoride batteries suffer from poor high-rate discharge capability and high heat generation, which limits their widespread application to some extent. Existing technologies utilize methods that combine fluoride with other materials to improve the high-rate discharge capability and reduce battery heat generation. Chinese patent CN 118572086A discloses a sulfur-selenium compound-modified fluoride cathode material, its preparation method, and a lithium primary battery cathode. Sulfur-selenium compounds have similar chemical properties to sulfur and selenium, but possess higher conductivity and higher specific energy than sulfur and selenium. Combining them with fluoride improves specific energy and rate performance to some extent; however, the resulting battery can only discharge at a 40C rate, and it fails to address the problem of high temperature rise during battery discharge. Summary of the Invention
[0003] In view of the above problems, the present invention provides a method for preparing a fluorinated carbon / niobium pentoxide hybrid cathode, which improves the rate performance of the corresponding lithium / fluorinated carbon battery, and at the same time improves the problem of high heat generation in lithium fluorinated carbon batteries during discharge.
[0004] To achieve the above objectives, the technical solution of the present invention is as follows:
[0005] This invention provides a method for preparing a carbon fluoride / niobium pentoxide composite cathode, the method comprising the following steps:
[0006] (1) Preparation of carbon precursor / niobium pentoxide composite material: Niobium pentoxide and carbon precursor are ball-milled and mixed at a certain mass ratio; the mass ratio of carbon precursor to niobium pentoxide is (60-90):(10-40); the niobium pentoxide is nanoscale; the niobium pentoxide includes one or more of TT-niobium pentoxide, T-niobium pentoxide, B-niobium pentoxide, N-niobium pentoxide, P-niobium pentoxide, M-niobium pentoxide, and H-niobium pentoxide;
[0007] (2) Preparation of fluorinated carbon / niobium pentoxide composite material: The composite material obtained in step (1) was prepared by gas phase fluorination to obtain fluorinated carbon / niobium pentoxide composite material;
[0008] (3) Preparation of fluorinated carbon / niobium pentoxide cathode: Fluorinated carbon / niobium pentoxide cathode is prepared by slurry coating method; the conductive agent includes one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes and graphene.
[0009] As a further preferred embodiment of the present invention, the niobium pentoxide particle size in step (1) is 200-500 nm.
[0010] As a further preferred embodiment of the present invention, the carbon precursor in step (1) is one or more of graphite, graphene, carbon nanotubes, carbon fibers, activated carbon, hard carbon, KB, soft carbon, super P, and mesophase carbon spheres.
[0011] As a further preferred embodiment of the present invention, the ball-to-material mass ratio during ball milling in step (1) is (1-10):1, the ball milling time is 2-10, and the ball milling speed is 400-800 r / min.
[0012] As a further preferred embodiment of the present invention, step (2) involves placing the composite material obtained in step (1) in a tubular furnace and introducing an inert gas at room temperature to remove air from the tubular furnace.
[0013] As a further preferred embodiment of the present invention, the gas phase in the gas phase fluorination method described in step (2) refers to one or more of fluorine gas, fluorine / argon mixture, fluorine / nitrogen mixture, and nitrogen fluoride (NF3); the fluorination temperature is 100-800℃; the fluorination time is 4-15h; and the fluorine-carbon molar ratio in the obtained fluorinated carbon material is 0.7-1.
[0014] As a further preferred embodiment of the present invention, a fluorinated carbon / niobium pentoxide positive electrode is prepared by a slurry coating method. Specifically, fluorinated carbon / niobium pentoxide, binder, and conductive agent are mixed in a certain proportion, a solvent is added to form a slurry, and after stirring evenly, a fluorinated carbon / niobium pentoxide slurry is obtained. The slurry is then coated onto a current collector, and after removing the solvent, a fluorinated carbon / niobium pentoxide positive electrode sheet is obtained.
[0015] As a further preferred embodiment of the invention, the adhesive comprises polyvinylidene fluoride (PVDF).
[0016] As a further preferred embodiment of the present invention, the solvent comprises N-methylpyrrolidone (NMP).
[0017] As a further preferred embodiment of the present invention, the current collector includes a composite aluminum foil current collector.
[0018] As a further preferred embodiment of the present invention, the mass ratio of fluorinated carbon / niobium pentoxide: binder: conductive agent is (100-300):(2-50):1.
[0019] This invention provides a fluorinated carbon / niobium pentoxide hybrid cathode prepared by the above preparation method;
[0020] The present invention also provides a lithium / carbon fluoride primary battery comprising the aforementioned hybrid positive electrode.
[0021] The beneficial effects of this invention are as follows:
[0022] 1. The conductive agent provided by this invention is a one-dimensional or two-dimensional conductive agent, which plays a supporting and connecting role for fluorinated carbon and niobium pentoxide electrode materials, helping the two to exert a synergistic effect, improve discharge capacity, rate performance and reduce battery heat generation.
[0023] 2. The nano-sized TT-niobium pentoxide, T-niobium pentoxide, B-niobium pentoxide, N-niobium pentoxide, P-niobium pentoxide, M-niobium pentoxide, and H-niobium pentoxide selected in this invention have unique crystal structures that enable ultra-high-speed lithium-ion storage dynamics. They do not generate heat during discharge and have good thermal conductivity. Therefore, they can reduce battery heat generation and minimize safety hazards while increasing battery capacity. Detailed Implementation
[0024] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.
[0025] Table 1
[0026]
[0027]
[0028] Note: The blank parts are the same as in Example 1.
[0029] Example 1
[0030] (1) Preparation of activated carbon / H-niobium pentoxide composite material: Activated carbon and nano-sized (200-500nm) H-niobium pentoxide were mechanically ball-milled at a mass ratio of 80:20, wherein the mass ratio of ball to material was 5:1, the ball milling time was 10h, and the ball milling speed was 500r / min; (2) Preparation of activated carbon / H-niobium pentoxide composite material: The mixed material obtained in step (1) was placed in a tube furnace, and an inert gas was introduced at room temperature to remove the air in the tube furnace. Then, a fluorine / argon mixed gas was introduced to fluorinate the carbon precursor-graphite. The fluorination temperature was 300℃ and the fluorination time was 10h; The fluorine-carbon molar ratio in the fluorinated graphite material was 0.9; (3) Preparation of fluorinated carbon / H-niobium pentoxide: Fluorinated carbon / H-niobium pentoxide cathode was prepared by slurry coating method. Fluorinated carbon / H-niobium pentoxide:polyvinylidene fluoride (PVDF):conductive agent (single-walled carbon nanotubes) were mixed in a mass ratio of 96:3.52:0.48 and homogenized with N-methylpyrrolidone (NMP) solvent. After thorough stirring, a fluorinated carbon / H-niobium pentoxide slurry was obtained. This slurry was coated onto a composite aluminum foil current collector and dried at 85°C to obtain the fluorinated carbon / H-niobium pentoxide positive electrode. A lithium / fluorinated carbon battery was assembled using this as the positive electrode and lithium metal as the negative electrode. The separator was Celgard 2400, and the electrolyte was 1 mol / L potassium perchlorate / propylene carbonate / dimethyl carbonate / ethyl methyl carbonate / sulfolane (25:40:20:15 V / V). The discharge performance of the battery at 0.1C and 80C rates was tested, and the corresponding discharge specific capacity and discharge specific energy were obtained. The surface temperature of the lithium / carbon fluoride battery was monitored during the discharge process at 0.1C, and its temperature change during the discharge process was recorded.
[0031] Example 2
[0032] Fluorinated carbon / niobium pentoxide hybrid cathode and lithium / fluorinated carbon battery were prepared using the same method as in Example 1. The difference was that the niobium pentoxide used in step (1) was nanoscale (200-500nm) M-niobium pentoxide.
[0033] Example 3
[0034] Fluorinated carbon / niobium pentoxide hybrid cathode and lithium / fluorinated carbon battery were prepared using the same method as in Example 1. The difference was that the niobium pentoxide used in step (1) was nanoscale (200-500nm) T-niobium pentoxide.
[0035] Example 4
[0036] Fluorinated carbon / niobium pentoxide hybrid cathode and lithium / fluorinated carbon battery were prepared using the same method as in Example 1. The difference was that the niobium pentoxide used in step (1) was nanoscale (200-500nm) N-niobium pentoxide.
[0037] Examples 5-7
[0038] Fluorinated carbon / niobium pentoxide composite material and battery were prepared using the same method as in Example 1, except that the mass ratio of carbon precursor to niobium pentoxide in step (1) was 70:30, 60:40 and 90:10, respectively.
[0039] Example 8
[0040] Fluorinated carbon / niobium pentoxide composite material and battery were prepared using the same method as in Example 1, except that the conductive agent in step (3) was graphene.
[0041] Examples 9-10
[0042] Fluorinated carbon / niobium pentoxide composite material and battery were prepared using the same method as in Example 1, except that the mass ratio of fluorinated carbon / niobium pentoxide to conductive agent in step (3) was 100:1 and 300:1, respectively.
[0043] Comparative Example 1
[0044] The battery was prepared using the same method as in Example 1, except that the positive electrode was a fluorinated carbon positive electrode and niobium pentoxide was not added.
[0045] Comparative Example 2
[0046] The battery was prepared using the same method as in Example 1, except that the positive electrode was a fluorinated carbon / sulfur selenium compound (SeS2) positive electrode (CN 118572086 A).
[0047] Comparative Examples 3-4
[0048] Fluorinated graphite / niobium pentoxide composite material and battery were prepared using the same method as in Example 1, except that the mass ratio of carbon precursor to niobium pentoxide in step (1) was 95:5 and 55:45, respectively.
[0049] Comparative Example 5
[0050] Fluorinated graphite / niobium pentoxide composite material and battery were prepared using the same method as in Example 1, except that the conductive agent in step (3) was acetylene black.
[0051] Comparative Examples 6-7
[0052] Fluorinated graphite / niobium pentoxide composite materials and batteries were prepared using the same method as in Example 1, except that the mass ratios of fluorinated carbon / niobium pentoxide to the conductive agent in step (3) were 90:1 and 400:1, respectively.
[0053] Comparative Example 8
[0054] Fluorinated carbon / niobium pentoxide hybrid cathode and lithium / fluorinated carbon battery were prepared using the same method as in Example 1. The difference was that the niobium pentoxide used in step (1) was nanoscale (200-500nm) α-niobium pentoxide.
[0055] Comparative Example 9
[0056] Fluorinated carbon / niobium pentoxide hybrid cathode and lithium / fluorinated carbon battery were prepared using the same method as in Example 1, except that the niobium pentoxide used in step (1) was micron-sized (1-5μm) H-niobium pentoxide.
[0057] Comparative Example 10
[0058] Fluorinated graphite / niobium pentoxide composite material and battery were prepared using the same method as in Example 1, except that the conductive agent in step (3) was super P.
[0059] Comparative Example 11
[0060] Fluorinated carbon / niobium pentoxide hybrid cathode and lithium / fluorinated carbon battery were prepared using the same method as in Example 1. The difference was that the niobium pentoxide used in step (1) was nanoscale (200-500nm) RS-niobium pentoxide.
[0061] Analysis of Experimental Results
[0062] As shown in Table 2, when the electrode composition is within the range of this invention (e.g., Examples 1-10), the corresponding battery cell exhibits the best overall performance using the preparation method of this invention. Specifically, it has a high specific capacity (>1050 mAh / g) at a 0.1C discharge rate and a specific capacity exceeding 440 mAh / g at an 80C discharge rate, indicating a high 80C / 0.1C capacity retention rate (over 40%). This demonstrates the superior rate performance of the corresponding battery. Furthermore, the battery surface temperature is low (below 55°C) during 0.1C discharge, indicating that the lithium fluoride carbon battery using the fluorinated carbon / niobium pentoxide cathode of this invention generates less heat and has better thermal diffusivity during discharge, reducing potential safety hazards. During discharge, niobium pentoxide and fluorinated carbon react simultaneously. The former contributes to capacity without generating heat, increasing the overall battery capacity while reducing heat generation (battery temperature rise). Additionally, the unique crystal structure of niobium pentoxide gives it excellent lithium-ion diffusion capabilities, ultimately resulting in superior rate performance.
[0063] Compared with the examples, when niobium pentoxide was not added to the fluorinated carbon cathode (Comparative Example 1), the material composited with fluorinated carbon was not within the scope of this invention (Comparative Example 2), the amount of niobium pentoxide added (Comparative Examples 3-4), the type of conductive agent in the electrode was not within the scope of this invention (Comparative Examples 5, 10), the ratio of fluorinated carbon / niobium pentoxide to conductive agent (Comparative Examples 6-7), the crystal phase of niobium pentoxide (Comparative Examples 8, 11), and the particle size of niobium pentoxide (Comparative Example 9) were not within the scope of protection of this invention, the corresponding battery capacity was low (<900mAh / g, 0.1C); at an 80C discharge rate, the specific capacity was less than 200mAh / g, i.e., (80C / 0.1C) the capacity retention was low, only about 15-18%; the corresponding battery showed low capacity retention during 0.1C discharge. The battery surface temperature is relatively high, reaching 90℃ (Comparative Example 1) or close to 90℃ (Comparative Examples 2-11). This will lead to side reactions such as electrolyte decomposition and battery swelling, posing certain safety hazards. The conductive agent provided by this invention is a one-dimensional or two-dimensional conductive agent, which plays a supporting and connecting role for fluorinated carbon and niobium pentoxide electrode materials, helping them to exert a synergistic effect, improve discharge capacity, and reduce battery heat generation. In summary, compared with the preparation method of this invention, the batteries in the above comparative examples have poorer capacity, rate performance, and heat diffusivity during battery discharge. See Table 2, which shows the specific capacity, capacity retention rate, and maximum surface temperature of the battery cells during discharge at 0.1C for the electrodes prepared in the examples and comparative examples at different rates (0.1C and 80C).
[0064] In summary, the fluorinated carbon / niobium pentoxide composite material obtained by the preparation method of this invention has the following advantages: the use of a special conductive agent improves the conductivity of the fluorinated carbon material, increases its electrical conductivity, alleviates the voltage hysteresis phenomenon in the discharge of lithium fluorinated carbon batteries, and improves the rate performance of the battery; niobium pentoxide can serve as an active material, contributing to the discharge capacity and improving the battery's capacity performance, thereby enhancing its energy performance; niobium pentoxide, as an active material, does not release heat during discharge, reducing the accumulation of heat on the surface of the lithium / fluorinated carbon battery, thus lowering the battery surface temperature and reducing the safety hazards it poses; niobium pentoxide material has intrinsically high lithium-ion diffusion capability, which can improve the battery's rate charge and discharge capability.
[0065] Table 2 Performance of Lithium / Fluorocarbon Battery Cells
[0066]
[0067] Note: In the attached table, 80C / 0.1C - capacity retention (%) refers to the discharge specific capacity of a single cell at 80C rate / discharge specific capacity of a single cell at 0.1C rate * 100%; the highest temperature on the battery surface during discharge refers to the highest temperature detected by the battery due to heat release during the discharge process at 0.1C rate.
Claims
1. A method for preparing a carbon fluoride / niobium pentoxide mixed cathode, characterized in that: Includes the following steps: (1) Preparation of carbon precursor / niobium pentoxide composite material: Niobium pentoxide and carbon precursor are ball-milled and mixed at a certain mass ratio; the mass ratio of carbon precursor to niobium pentoxide is (60-90):(10-40); the niobium pentoxide is nanoscale; the niobium pentoxide includes one or more of TT-niobium pentoxide, T-niobium pentoxide, B-niobium pentoxide, N-niobium pentoxide, P-niobium pentoxide, M-niobium pentoxide, and H-niobium pentoxide; (2) Preparation of fluorinated carbon / niobium pentoxide composite material: The composite material obtained in step (1) was prepared by gas phase fluorination to obtain fluorinated carbon / niobium pentoxide composite material; (3) Preparation of fluorinated carbon / niobium pentoxide cathode: Fluorinated carbon / niobium pentoxide cathode is prepared by slurry coating method; the conductive agent includes one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes and graphene.
2. The preparation method according to claim 1, characterized in that: The niobium pentoxide particle size mentioned in step (1) is 200-500 nm.
3. The preparation method according to claim 1, characterized in that: The carbon precursor mentioned in step (1) is one or more of the following: graphite, graphene, carbon nanotubes, carbon fibers, activated carbon, hard carbon, KB, soft carbon, super P, and mesophase carbon spheres.
4. The preparation method according to claim 1, characterized in that: In step (1), the ball-to-material mass ratio during ball milling is (1-10):1, the ball milling time is 2-10, and the ball milling speed is 400-800 r / min.
5. The preparation method according to claim 1, characterized in that: Step (2) involves placing the composite material obtained in step (1) into a tube furnace and introducing an inert gas at room temperature to remove air from the tube furnace.
6. The preparation method according to claim 1, characterized in that: In step (2), the gas phase in the gas phase fluorination method refers to one or more of the following: fluorine gas, fluorine / argon mixture, fluorine / nitrogen mixture, and fluorination; the fluorination temperature is 100-800℃; the fluorination time is 4-15h; and the fluorine-carbon molar ratio in the obtained fluorinated carbon material is 0.7-1.
7. The preparation method according to claim 1, characterized in that: Fluorinated carbon / niobium pentoxide positive electrode is prepared by a slurry coating method. Specifically, fluorinated carbon / niobium pentoxide, binder, and conductive agent are mixed in a certain proportion, solvent is added and homogenized, and after stirring evenly, fluorinated carbon / niobium pentoxide slurry is obtained. The above slurry is coated on a current collector, and after removing the solvent, fluorinated carbon / niobium pentoxide positive electrode sheet is obtained.
8. The preparation method according to claim 7, characterized in that: The mass ratio of fluorinated carbon / niobium pentoxide: binder: conductive agent is (100-300):(2-50):
1.
9. A fluorinated carbon / niobium pentoxide mixed cathode prepared by the method according to any one of claims 1-8.
10. The application of the fluorinated carbon / niobium pentoxide hybrid cathode as described in claim 9 in a lithium / fluorinated carbon primary battery.