阅读说明：本技术 锂原电池用铬氧化物/氟化碳/高导电性物质复合材料 (Chromium oxide/carbon fluoride/highly conductive substance composite material for lithium primary battery ) 是由 滕久康 王畅 王庆杰 张亮 张红梅 陈晓涛 石斌 于 2021-08-10 设计创作，主要内容包括：本发明属于电极材料制作技术领域,具体涉及锂原电池用铬氧化物/氟化碳/高导电性物质复合材料,所述电极材料是以三氧化铬为反应原料,以氟化碳、高导电性物质预混物为掺杂材料,将反应原料与掺杂材料依次经球磨、通氧烧结而成；本发明选择氟化碳、高导电性物质作为掺杂材料,以三氧化铬为制备铬氧化物的原料,在铬氧化物形成的全过程中引入掺杂材料,使得CrO-(3)在高温下经历液化、分解反应过程的同时氟化碳、高导电性物质能均匀地掺杂于铬氧化物表面或嵌入内部,有效的提高了铬氧化物的首次放电比容量和倍率性能。(The invention belongs to the technical field of electrode material manufacturing, and particularly relates to a chromium oxide/carbon fluoride/high-conductivity substance composite material for a lithium primary battery, wherein the electrode material is prepared by taking chromium trioxide as a reaction raw material and taking a carbon fluoride and high-conductivity substance premix as a doping material, and sequentially performing ball milling and oxygen introduction sintering on the reaction raw material and the doping material; the invention selects carbon fluoride and high-conductivity substances as doping materials, uses chromium trioxide as a raw material for preparing chromium oxide, and introduces the doping materials in the whole process of forming the chromium oxide to ensure that CrO 3 Undergoes liquefaction at high temperature,During the decomposition reaction process, the carbon fluoride and the high-conductivity substance can be uniformly doped on the surface of the chromium oxide or embedded in the chromium oxide, so that the first discharge specific capacity and the rate capability of the chromium oxide are effectively improved.)

1. The chromium oxide/carbon fluoride/high-conductivity substance composite material for the lithium primary battery is characterized in that the electrode material is prepared by taking chromium trioxide as a reaction raw material and taking carbon fluoride and high-conductivity substance premix as a doping material, and sequentially performing ball milling and oxygen introduction sintering on the reaction raw material and the doping material; the chromium oxide is Cr₈O₂₁、Cr₂O₅、Cr₅O₁₂Any of the above.

2. The chromium oxide/fluorocarbon/highly conductive material composite for primary lithium battery according to claim 1, wherein the chromium oxide is Cr₈O₂₁。

3. The chromium oxide/carbon fluoride/highly conductive substance composite material for a primary lithium battery according to claim 1, wherein the mass ratio of the chromium trioxide, the carbon fluoride and the highly conductive substance is (70 to 85): (10-20): (5-10).

4. The chromium oxide/carbon fluoride/highly conductive substance composite material for a primary lithium battery according to claim 1, wherein the highly conductive substance is any one of graphene, carbon nanotubes, and silver powder.

5. The chromium oxide/carbon fluoride/highly conductive substance composite material for a primary lithium battery according to claim 1 or 4, wherein the highly conductive substance is graphene.

6. The chromium oxide/fluorocarbon/highly conductive material composite for primary lithium batteries according to claim 1, wherein said ball milling is carried out under the following conditions: the rotating speed is 220-.

7. The chromium oxide/fluorocarbon/highly conductive material composite for primary lithium battery as claimed in claim 1, wherein said oxygen-supplying sintering is carried out under the following conditions: the oxygen flow rate is 20-40ml/min, the sintering time is 24-48h, and the sintering temperature is determined according to the generation temperature of the chromium oxide.

8. The chromium oxide/fluorocarbon/high-conductivity material composite for primary lithium battery according to claim 1, wherein the Cr is₈O₂₁The formation temperature of (A) is 250-290 ℃.

9. The chromium oxide/fluorocarbon/highly conductive material composite for primary lithium batteries according to any one of claims 1 to 8, wherein the method for preparing said composite comprises the steps of:

preparation of a doped material: mixing carbon fluoride, a high-conductivity substance and water, performing ultrasonic dispersion for 30 minutes, and then drying to obtain a uniformly mixed doped material;

② according to CrO₃: carbon fluoride: graphene (70-85): (10-20): (5-10) ball-milling chromium trioxide and the doping material for 2-6 hours at the rotating speed of 300r/min to uniformly disperse the material;

thirdly, placing the material obtained in the second step into a tube furnace, sintering for 24-48h at an oxygen flow rate of 20-40ml/min and a sintering temperature of 250-290 ℃, taking out and grinding the material to powder, and sieving the powder to obtain Cr₈O₂₁A/fluorocarbon/graphene composite material.

10. The chromium oxide/fluorocarbon/highly conductive material composite material for lithium primary batteries according to claim 9, wherein the mesh size is 180-250 mesh.

Technical Field

The invention belongs to the technical field of electrode material manufacturing, and particularly relates to a chromium oxide/carbon fluoride/high-conductivity substance composite material for a lithium primary battery.

Background

With the higher requirements of small electronic devices and military equipment on the specific energy of lithium batteries, the metal lithium batteries with high specific energy characteristics become research hotspots. Lithium primary batteries (lithium primary batteries) are favored by researchers because of a series of advantages, such as high operating voltage, high specific energy, and long storage life. The key to the performance of the lithium primary battery lies in the selection of the positive electrode material, and carbon fluoride, manganese dioxide, sulfur dioxide, thionyl chloride and the like are the commercial positive electrode materials of the lithium primary battery. However, the specific energy and specific power of the battery are difficult to be further improved due to the limitation of the system of the primary lithium battery. Thus, the multi-electron reacted chromium oxide (mainly Cr)₈O₂₁) Entering the human vision. Cr (chromium) component₈O₂₁Has high theoretical energy density (1210Wh/Kg) and lithium storage capacity, high first discharge specific capacity (390mAh/g), high working voltage (3.0V), low cost and other advantages when being used as the positive electrode material of the lithium primary battery. But Cr₈O₂₁The material has poor conductivity, so that the discharge specific capacity of the material is greatly different from the theoretical capacity, and the discharge capacity of the material under high current is greatly limited. Therefore, how to treat Cr₈O₂₁The modification of materials to make them have the characteristics of high specific energy and high power, which is the direction of urgent research.

Research on the performance of carbon fluoride-doped chromium oxide cells (Deng Korea, Power technology, 2021,45(05)) reported the use of carbon fluoride and chromium oxide (CrO)_X) Simply ball milling and mixing, the discharge capacity of the battery is the sum of the capacity of the battery and the capacity of the battery has a certain valueAnd (5) lifting. However, the simple physical mixing has the problems of uneven mixing, unstable discharge curve, large difference between discharge platforms and difficult stable discharge of the battery;

the patent CN 112201773A adopts a rotary spraying method to coat metal copper on Cr₂O₅Surface, promote Cr₂O₅The conductivity of the material, the second discharge specific capacity reaches 409.5mAh/g, and the discharge voltage platform is also obviously improved. However, since copper occupies a certain mass of the electrode sheet after coating with copper, the amount of the electrode active material is rather decreased, and the first discharge capacity is rather decreased in the case of the primary lithium battery.

The patent CN 112194182A prepares chromium oxide containing lithiated vulcanized polyacrylonitrile, and improves the first coulombic efficiency and the second discharge specific capacity of the material. But the specific capacity of the material for the first discharge is still lower, only 326.5mAh/g, and the specific capacity is lower for a lithium primary battery;

patent CN 111146412A lithium storage material Li with high charge capacity₅FeO₄High discharge capacity Cr₈O₂₁And the conductive agent are mixed according to a certain proportion to prepare the composite phase anode material. The composite phase anode material has 255mAh/g reversible discharge capacity, a discharge voltage platform is 3.0V, and a first discharge condition patent is not given, so that whether the composite phase anode material is applied to a lithium primary battery or not can not be judged to have a good effect;

patent CN 102339994A combines together chromium oxide and graphite alkene through physics or chemical mode, and the effectual electric conductivity that has promoted the combined material, and the cycling performance also has promoted by a wide margin. However, it is very difficult to chemically combine the chromium oxide and the graphene, the improvement effect of the simple physical mixing on the conductivity of the material is limited, and the chromium oxide is very sensitive to the solvent, and particularly under the high-temperature and high-pressure environment, chromic anhydride (H) is very easily generated₂CrO₄) Therefore, it is very difficult to prepare the chromium oxide/graphene composite material by a hydrothermal method.

In summary, the current research direction is focused on improving the conductivity of chromium oxide, but most researchers have prepared chromium oxide (e.g., Cr)₈O₂₁、Cr₂O₅Etc.) to remove the doping or coating, the obtained composite material has the problems of uneven coating and the like, and the discharge effect is poor.

Disclosure of Invention

The invention provides a chromium oxide/carbon fluoride/high-conductivity substance composite material for a lithium primary battery aiming at the defects of the prior art.

The method is realized by the following technical scheme:

the electrode material is prepared by taking chromium trioxide as a reaction raw material and taking carbon fluoride and a high-conductivity substance premix as a doping material, and sequentially performing ball milling and oxygen introduction sintering on the reaction raw material and the doping material; the chromium oxide is Cr₈O₂₁、Cr₂O₅、Cr₅O₁₂Any of the above.

Preferably, the chromium oxide is Cr₈O₂₁。

The mass ratio of the chromium trioxide to the carbon fluoride to the high-conductivity substance is (70-85): (10-20): (5-10).

The high-conductivity substance is any one of graphene, carbon nanotubes and silver powder; preferably graphene.

Preparing the doping material: mixing the carbon fluoride, the high-conductivity substance and water, performing ultrasonic dispersion for 30 minutes, and then drying to obtain the uniformly mixed doped material.

The working conditions of the ball milling are as follows: the rotating speed is 220-.

The working conditions of the oxygen-introducing sintering are as follows: the flow rate of oxygen is 20-40ml/min, the sintering time is 24-48h, and the sintering temperature is determined according to the generation temperature of chromium oxide.

The Cr is₈O₂₁The formation temperature of (A) is 250-290 ℃.

The preparation method of the chromium oxide/carbon fluoride/graphene composite material for the lithium primary battery comprises the following steps:

preparation of a doped material: mixing carbon fluoride, a high-conductivity substance and water, performing ultrasonic dispersion for 30 minutes, and then drying to obtain a uniformly mixed doped material;

② according to CrO₃: carbon fluoride: graphene (70-85): (10-20): (5-10) ball-milling chromium trioxide and the doping material for 2-6 hours at the rotating speed of 300r/min to uniformly disperse the material;

thirdly, placing the material obtained in the second step into a tube furnace, sintering for 24-48h at an oxygen flow rate of 20-40ml/min and a sintering temperature of 250-290 ℃, taking out and grinding the material to powder, and sieving the powder to obtain Cr₈O₂₁A/fluorocarbon/graphene composite material.

The number of the sieving meshes is 180 meshes and 250 meshes; preferably 200 mesh.

Has the advantages that:

the invention selects carbon fluoride and high-conductivity substances as doping materials, uses chromium trioxide as a raw material for preparing chromium oxide, and introduces the doping materials in the whole process of forming the chromium oxide to ensure that CrO₃The carbon fluoride and the high-conductivity substance can be uniformly doped on the surface of the chromium oxide or embedded in the chromium oxide while undergoing liquefaction and decomposition reaction processes at high temperature, so that the first discharge specific capacity and the rate capability of the chromium oxide are effectively improved.

With pure Cr₈O₂₁In contrast, Cr₈O₂₁The specific discharge capacity, the discharging capacity under large current and the conductivity of the/carbon fluoride/graphene composite material are greatly improved. The method of the invention enables the carbon fluoride and the graphene to be uniformly attached to the Cr₈O₂₁A surface.

The rotating speed of the ball mill is controlled, so that the reaction raw material and the doped raw material can be uniformly dispersed, and the surface micro-morphology of the chromium trioxide can be changed by utilizing the mechanical force and the frictional heat, so that the penetration sites of the doped raw material can be opened; meanwhile, the granularity of the materials is controlled by controlling the grinding rotating speed, so that the reaction state of each material is stable in the calcining process, and the generation of chromium oxide is favorably ensured. The invention discovers in research that: if the rotating speed is lower than 220r/min, the material is unevenly distributed, so that the electrochemical performance of the end product is greatly influenced, and the material is represented as lower conductivity(ii) a When the rotating speed is higher than 300r/min, the materials can be uniformly distributed, but the activity of the materials is too high, so that CrO is generated₃The decomposition of the composite material is over-active, so that the structure of the composite material is collapsed, and the capacitance of the material is greatly influenced.

The method controls the granularity of the final product, is beneficial to improving the specific surface area of the final product, further ensures the effect of the final product in the manufacturing process of the positive plate, simultaneously prevents the final product from being easy to agglomerate due to too large granularity and too small diameter, and can not be uniformly mixed with other materials of the positive plate, and simultaneously, the performance of the material is outstanding due to too large granularity and too small diameter, and further the use effect is influenced.

Drawings

FIG. 1 shows Cr prepared in example 1₈O₂₁XRD test pattern of the/fluorocarbon/graphene composite material;

FIG. 2 shows Cr prepared in example 1₈O₂₁SEM test picture of the/carbon fluoride/graphene composite material, wherein a picture is magnified by 2000, and b picture is magnified by 5000;

FIG. 3 shows Cr prepared in example 1₈O₂₁EDS elemental analysis chart of/carbon fluoride/graphene composite material;

FIG. 4 shows Cr prepared in example 1₈O₂₁Carbon fluoride/graphene composite material and pure Cr₈O₂₁Discharge profile of the material;

FIG. 5 shows Cr prepared in example 1₈O₂₁Carbon fluoride/graphene composite material and pure Cr₈O₂₁An electrochemical impedance plot of the material;

FIG. 6 shows CrO as a raw material in example 1₃Thermogravimetric TG-DSC curve of;

FIG. 7 shows Cr prepared in comparative example 2₈O₂₁Graphene composite material and pure Cr₈O₂₁Discharge profile of the material;

FIG. 8 shows Cr prepared in comparative example 3₈O₂₁Carbon fluoride composite and pure Cr₈O₂₁Discharge profile of the material.

Detailed Description

The following is a detailed description of the embodiments of the present invention, but the present invention is not limited to these embodiments, and any modifications or substitutions in the basic spirit of the embodiments are included in the scope of the present invention as claimed in the claims.

Example 1

Cr for lithium primary battery₈O₂₁The preparation method of the/fluorocarbon/graphene composite material comprises the following steps:

preparation of a doped material: mixing carbon fluoride, graphene and water, performing ultrasonic dispersion for 30 minutes, and then drying until water is completely removed to obtain a uniformly mixed doped material;

② according to CrO₃: carbon fluoride: graphene 80: 15: 5, ball-milling the chromium trioxide and the doping material for 6 hours at the rotating speed of 300r/min to uniformly disperse the materials;

thirdly, placing the obtained substance in the second step into a tube furnace, introducing oxygen at 270 ℃, sintering for 48 hours, taking out, grinding into powder, and sieving with a 200-mesh sieve to obtain Cr₈O₂₁A/fluorocarbon/graphene composite; the flow rate of the oxygen is 25 ml/min;

fourthly, the composite material, the SuperP, the CNTS and the PVDF (5 mass percent solution) are mixed according to the mass ratio of 80:6:4:10 to prepare a positive pole piece, a lithium metal piece is used as a negative pole, and an electrolytic liquid system is 1mol/L LiPF₆DMC, EM prepares CR2025 button cell; testing the discharge performance, the discharge current density is 0.05mA cm^-2、1.0mA·cm^-2Discharge cutoff voltage 2.0V;

FIG. 1 shows that Cr₈O₂₁The whole structure of the alloy is complete, and the doping of the carbon fluoride and the graphene does not damage Cr₈O₂₁The characteristic peak of the carbon fluoride is relatively complete, which shows that the carbon fluoride structure is not damaged; FIG. 2 is an SEM image showing that the dopant is uniformly distributed on the surface of the material; as can be seen from fig. 3: the C element and the F element are uniformly distributed in Cr₈O₂₁On the surface, the C element is more than the F element, because the graphene also contributes to part of the C element; the discharge results in FIG. 4 show that the composite material has a discharge current density of 0.05mA cm^-2、1.0mA·cm^-2Is as followsThe specific discharge capacity is 415.20mAh g^-1、349.65mAh·g^-1The capacity retention rate is 84.21%; pure Cr₈O₂₁Specific discharge capacity of 371.38mAh g^-1、266.98mAh·g^-1The capacity retention rate is 71.89%, and the discharge specific capacity and the rate capability of the composite material are greatly improved; the electrochemical impedance results of FIG. 5 show that the charge transfer impedance values of the composite material are compared to pure Cr₈O₂₁The conductivity is obviously improved by about half; as can be seen from fig. 6: CrO₃The thermal decomposition temperature is about 300 ℃, which is far lower than the decomposition temperature of the carbon fluoride, so that the structure of the carbon fluoride is not damaged.

Example 2:

cr for lithium primary battery₈O₂₁The preparation method of the/fluorocarbon/graphene composite material comprises the following steps:

preparation of a doped material: mixing carbon fluoride, graphene and water, performing ultrasonic dispersion for 30 minutes, and then drying until water is completely removed to obtain a uniformly mixed doped material;

② according to CrO₃: carbon fluoride: graphene 85: 10: 5, ball-milling the chromium trioxide and the doping material for 6 hours at the rotating speed of 300r/min to uniformly disperse the materials;

thirdly, placing the obtained substance in the second step into a tube furnace, introducing oxygen at 270 ℃, sintering for 48 hours, taking out, grinding into powder, and sieving with a 200-mesh sieve to obtain Cr₈O₂₁A/fluorocarbon/graphene composite; the oxygen flow rate was 25 ml/min.

Example 3:

cr for lithium primary battery₈O₂₁The preparation method of the/fluorocarbon/graphene composite material comprises the following steps:

preparation of a doped material: mixing carbon fluoride, graphene and water, performing ultrasonic dispersion for 30 minutes, and then drying until water is completely removed to obtain a uniformly mixed doped material;

② according to CrO₃: carbon fluoride: graphene 75: 20: 5, the chromium trioxide and the doping material are mixed at the rotating speed of 3Ball milling is carried out for 6 hours under the condition of 00r/min, so that the materials are uniformly dispersed;

thirdly, placing the obtained substance in the second step into a tube furnace, introducing oxygen at 270 ℃, sintering for 48 hours, taking out, grinding into powder, and sieving with a 200-mesh sieve to obtain Cr₈O₂₁A/fluorocarbon/graphene composite; the oxygen flow rate was 25 ml/min.

Example 4:

cr for lithium primary battery₈O₂₁The preparation method of the/fluorocarbon/graphene composite material comprises the following steps:

preparation of a doped material: mixing carbon fluoride, graphene and water, performing ultrasonic dispersion for 30 minutes, and then drying until water is completely removed to obtain a uniformly mixed doped material;

② according to CrO₃: carbon fluoride: graphene 70: 20: 10, ball-milling the chromium trioxide and the doping material for 6 hours at the rotating speed of 300r/min to uniformly disperse the material;

thirdly, placing the obtained substance in the second step into a tube furnace, introducing oxygen at 270 ℃, sintering for 48 hours, taking out, grinding into powder, and sieving with a 200-mesh sieve to obtain Cr₈O₂₁A/fluorocarbon/graphene composite; the oxygen flow rate was 25 ml/min.

Comparative example 1

Pure Cr₈O₂₁The preparation method of the cathode material comprises the following steps:

putting chromium trioxide into a tube furnace for sintering, introducing oxygen atmosphere for protection at the oxygen flow rate of 25ml/min, heating to 270 ℃ at the speed of 5 ℃/min, and sintering at 270 ℃ for 48h to obtain pure Cr₈O₂₁A positive electrode material; and then the positive plate is prepared according to the method of the embodiment 1, and the CR2025 button cell is assembled.

Comparative example 2

Cr (chromium)₈O₂₁The preparation method of the graphene composite material comprises the following steps:

firstly, the prepared Cr₈O₂₁Mixing graphene according to a mass ratio of 90:10, and then carrying out ball milling at a rotating speed of 300r/min for 6 h;

② then oxygen is introduced into the tube furnace at 270 ℃ for burningPreparation of Cr in 6h₈O₂₁Graphene composite materials; the flow rate of oxygen is 25 ml/min;

taking out the sample product, grinding the sample product to powder, and then sieving the powder by a 200-mesh sieve to obtain a composite material sample.

Fig. 7 shows that the rate performance of the material can be effectively improved by adding the graphene, but the overall specific discharge capacity is still low;

comparative example 3

Cr (chromium)₈O₂₁The preparation method of the/carbon fluoride composite material comprises the following steps:

firstly, the prepared Cr₈O₂₁Mixing the carbon fluoride according to the mass ratio of 90:10, and then carrying out ball milling at the rotating speed of 300r/min for 6 h;

② then introducing oxygen in a tube furnace at 270 ℃ for sintering for 6h to prepare Cr₈O₂₁Graphene composite materials; the flow rate of oxygen is 25 ml/min;

taking out the sample product, grinding the sample product to powder, and then sieving the powder by a 200-mesh sieve to obtain a composite material sample.

As can be seen from fig. 8: when fluorinated carbon and Cr₈O₂₁When the two are compounded alone, the discharge performance of the whole battery is deteriorated, because the conductivity of the two is poor, and the conductivity becomes worse after compounding, and therefore the discharge capacity cannot be fully discharged.