A CF x / Mn5O8 composite positive electrode material synthesis method

Abstract

The present invention discloses a synthesis method of a CF x / Mn5O8 composite cathode material, belonging to the field of primary lithium-carbon monofluoride batteries. It is characterized in that CF x and a manganese source are used as raw materials to obtain a precursor material with rod-shaped MnOOH grown on the surface of CF x through hydrothermal synthesis, and then it is calcined in an oxygen atmosphere to obtain a CF x / Mn5O8 composite material; when this composite material is used as the cathode of a primary lithium-carbon monofluoride battery, it has excellent high-current discharge performance, and the specific capacity reaches 505 mAh g ‑1 at a current density of 3000 mAg ‑1 . The rod-shaped Mn5O8 forms a network structure on the surface of CF x , effectively improving the electron conduction and ion transport processes, and at the same time providing more electrochemically active sites; the synthesis method of the present invention is simple, efficient, and low-cost, and has good application prospects in the field of primary lithium-ion batteries.

Description

Technical Field

[0001] The present invention belongs to the field of lithium-carbon fluoride primary batteries, and in particular relates to a CF x / Mn5O8 composite positive electrode material synthesis method. Background Art

[0002] With the advantages of high energy density, storage life, low self-discharge rate and good safety, lithium-carbon fluoride primary batteries currently have good application prospects in medical devices and military weapons and equipment. However, the carbon fluoride (CF) used in traditional lithium / carbon fluoride primary batteries x ) The electronic conductivity of the positive electrode material is low, and CF x The lithiation process will continuously generate inert LiF on the surface, inhibiting the battery reaction from continuing. x The large current discharge performance of the positive electrode is poor and the voltage hysteresis is obvious, which hinders the further promotion of lithium-carbon fluoride primary batteries.

[0003] In order to make up for the performance shortcomings of lithium / carbon fluoride primary batteries, it is urgent to improve CF x The researchers have tried a variety of related improvement methods, such as using different carbon source materials (graphite fluoride, graphene fluoride, carbon nanotube fluoride, etc.), regulating the structure of the cathode material (morphology, crystallinity, particle size, etc.), and optimizing the fluorination conditions (high-temperature gas phase fluorination, low-temperature fluorination, electrolytic synthesis, etc.). However, the above methods often have poor improvement effects, or are difficult to apply on a large scale due to limitations in raw materials, manufacturing processes and costs. In response to the above problems, CF x Combining with other positive electrode materials with good discharge platform and rate performance (such as manganese oxide) to prepare composite positive electrode materials often has the advantages of good rate performance and high voltage platform, thereby enhancing the discharge performance of lithium-carbon fluoride primary batteries at high current density. Summary of the invention

[0004] The object of the present invention is to provide a CF x The synthesis method of Mn5O8 composite positive electrode material has the advantages of good rate performance and high voltage platform when used as the positive electrode of lithium-carbon fluoride primary battery, which is helpful to improve the application value of lithium-carbon fluoride primary battery under high current density. The synthesis method is simple, efficient and low-cost.

[0005] According to the above invention purpose, the present invention adopts the following technical solution:

[0006] A CF x Synthesis method of CF / Mn5O8 composite material, the CF x / Mn5O8 composite positive electrode material is suitable for lithium-carbon fluoride primary battery, characterized in that CF x With manganese source as raw material, CF x The precursor material with rod-shaped MnOOH grown on the surface is then calcined in an oxygen atmosphere to obtain CF x / Mn5O8 composite materials.

[0007] Preferably, the synthesis method comprises the following steps:

[0008] CF was added in a mass ratio of 9:0.25–2. x , emulsifier dispersed in deionized water, stirred evenly; then added high-valent manganese source and low-valent manganese source in a molar ratio of 3:1-2, stirred evenly; the mixed solution was transferred to a hydrothermal kettle, heated at 150-220 ° C for 8-24 h for hydrothermal synthesis, and then cooled to room temperature; the obtained product was washed and dried at 60-100 ° C to obtain rod-shaped MnOOH grown on CF x The precursor material on the surface is further calcined at 250–400 °C in an oxygen atmosphere for 1–12 h to obtain rod-shaped Mn5O8 grown on CF x Surface product composite material CF x / Mn5O8.

[0009] Preferably, CF x The fluorinated carbons have different fluorine contents (where x=0.6-1.2), including at least one of fluorinated graphite, fluorinated graphene, and fluorinated carbon nanotubes.

[0010] Preferably, the emulsifier is at least one of the alkylphenol polyoxyethylene ether emulsifiers OP series, TX series, and NP series.

[0011] Preferably, CF x The mass ratio of manganese to high-valent manganese source is 3:0.25–2.

[0012] Preferably, the high-valent manganese source is one of potassium permanganate KMnO4 and potassium manganate K2MnO4, and the low-valent manganese source is one of manganese sulfate MnSO4, manganese nitrate Mn(NO3)2, and manganese chloride MnCl2.

[0013] Compared with the prior art, the present invention has the following beneficial technical effects:

[0014] 1. The present invention provides a CF x The synthesis method of / Mn5O8 composite positive electrode material uses common and easily available raw materials, a simple preparation process, strong repeatability, and is conducive to large-scale production. Mn5O8 has good lithium storage performance due to its unique layered structure and cationic valence state, and has low cost. As a composite component, it helps to improve CF xelectrochemical performance while controlling its cost.

[0015] 2. CF provided by the present invention x / Mn5O8 composite materials, rod-shaped Mn5O8 in CF x The network structure formed on the surface can promote the electronic conduction and ion transport of the composite material, and the larger specific surface area can provide more electrochemical active sites. At the same time, by changing the synthesis conditions, the structure and valence state of Mn5O8 can be regulated to obtain better electrochemical performance.

[0016] 3. CF provided by the present invention x When the / Mn5O8 composite material is used as the positive electrode of lithium / carbon fluoride primary battery, it retains the x The high specific capacity of the positive electrode solves the defects of poor high current discharge performance and obvious voltage hysteresis. x The positive electrode cannot effectively discharge 3000mAg -1 Under these conditions, CF x The discharge capacity of the Mn5O8 positive electrode can reach 505 mAh g -1 , and the voltage platform is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Comparative Example 1CF x XRD pattern of the material;

[0018] Figure 2 Example 1CF x XRD pattern of / Mn5O8 composite material;

[0019] Figure 3 Comparative Example 1CF x SEM images of materials;

[0020] Figure 4 Example 1CF x SEM image of / Mn5O8 composite material;

[0021] Figure 5 The CF of Comparative Example 1 is x The discharge curve of button cells assembled with positive electrode materials at different current densities;

[0022] Figure 6 The CF of Example 2 is x Discharge curves of button cells assembled with / Mn5O8 composite materials as positive electrode materials at different current densities. DETAILED DESCRIPTION

[0023] In order to better understand the technical content of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only intended to more clearly illustrate the present invention, but the scope of protection claimed by the present invention is not limited to the scope described in the following embodiments:

[0024] Example 1

[0025] This embodiment CF x The synthesis method of the Mn5O8 composite material comprises the following steps:

[0026] (1) 0.9 g CF x (x=0.9) and 0.1g OP-10 emulsifier were dispersed in 20mL deionized water and stirred for 60min; then 2.0mmol potassium permanganate and 0.7mmol manganese sulfate were added and stirred for 60min; the mixture was transferred to a 50ml hydrothermal kettle for hydrothermal synthesis, heated at 160℃ for 12h, and then cooled at room temperature for 5h; the obtained product was washed with deionized water and ethanol three times each, and dried at 60℃ for 12h to obtain rod-shaped MnOOH grown on CF x Surface precursor materials;

[0027] (2) The precursor was placed in a tube furnace and introduced into an oxygen atmosphere, and calcined at 350°C for 4 h at a heating rate of 2.5°C / min. The product was a composite material CF in which rod-shaped Mn5O8 grew on the surface of fluorinated carbon. x / Mn5O8.

[0028] Example 2

[0029] This embodiment CF x The synthesis method of the Mn5O8 composite material comprises the following steps:

[0030] (1) 0.9 g CF x (x=0.6) and 0.025g NP-10 emulsifier were dispersed in 20mL deionized water and stirred for 60min; then 1.8mmol potassium permanganate and 0.9mmol manganese nitrate were added and stirred for 60min; the mixture was transferred to a 50ml hydrothermal kettle for hydrothermal synthesis, heated at 150℃ for 24h, and then cooled at room temperature for 3h; the obtained product was washed three times with deionized water and ethanol respectively, and dried at 80℃ for 12h to obtain rod-shaped MnOOH grown on CF x Surface precursor materials;

[0031] (2) The precursor was placed in a tube furnace and introduced into an oxygen atmosphere, and calcined at 250°C for 12 h at a heating rate of 1°C / min. The product was a composite material CF in which rod-shaped Mn5O8 grew on the surface of fluorinated carbon. x / Mn5O8.

[0032] Example 3

[0033] This embodiment CF x The synthesis method of the Mn5O8 composite material comprises the following steps:

[0034] (1) 0.9 g CF x (x=1.2) and 0.2g TX-10 emulsifier were dispersed in 20mL deionized water and stirred for 60min; then 1.62mmol potassium manganate and 1.08mmol manganese chloride were added and stirred for 60min; the mixture was transferred to a 50ml hydrothermal kettle for hydrothermal synthesis, heated at 220℃ for 8h, and then cooled at room temperature for 12h; the obtained product was washed with deionized water and ethanol three times respectively, and dried at 100℃ for 12h to obtain rod-shaped MnOOH grown on CF x Surface precursor materials;

[0035] (2) The precursor was placed in a tube furnace and introduced into an oxygen atmosphere, and calcined at 400°C for 1 h at a heating rate of 5°C / min. The product was a composite material CF in which rod-shaped Mn5O8 grew on the surface of fluorinated carbon. x / Mn5O8.

[0036] Comparative Example 1

[0037] Using the raw material CF in the embodiment x (x=0.9) was used as a comparative material.

[0038] To prove that the CF synthesized by the present invention x The phase and morphology of the / Mn5O8 composite material were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) of Example 1 and Comparative Example 1. The results are shown in Figure 1-Figure 4 .

[0039] Comparative Example 1 CF x The XRD spectrum of Figure 1 As shown in Figure 1, the peak at 13.8° corresponds to the (001) crystal plane of fluorinated carbon, and its higher peak intensity indicates a higher fluorine content; its SEM image is shown in Figure 1. Figure 3 As shown, CF x The material has a layered structure.

[0040] In Example 1, the CF synthesized by the present invention x The XRD spectrum of the / Mn5O8 composite material is shown in Figure 2 As shown, it is Figure 1 Medium CF x Compared with the XRD spectrum of the original CF, the new peaks correspond to the characteristic peaks of Mn5O8, proving that Mn5O8 and the original CF x Effective compounding of materials; CF xSEM images of / Mn5O8 composite materials are shown in Figure 4 As shown, Figure 3 Medium CF x Compared with the SEM images of x surface.

[0041] To prove that the CF synthesized by the present invention x The electrochemical properties of the CF prepared in Example 1 were investigated. x / Mn5O8 composite material is used to prepare the positive electrode material of lithium / carbon fluoride primary battery, and assembled into lithium / carbon fluoride primary battery to test its performance, the steps are as follows:

[0042] (1) CF x / Mn5O8, conductive agent (super p), binder (polyvinylidene fluoride), solvent (N-methylpyrrolidone) were mixed at a mass ratio of 8:1:1:9 for 30 minutes to obtain a uniform slurry. The slurry was evenly coated on aluminum foil with a scraper with a thickness of 100μL, dried at 70℃ for 2h, and then cut into circular positive electrode sheets with a diameter of 10mm, and continued to dry at 100℃ for 12h.

[0043] (2) In an argon atmosphere glove box, a 2032-type button cell was assembled in the order of anode shell, spring sheet, stainless steel gasket, metal lithium sheet, diaphragm, electrolyte (1 mol / L LiPF6 dissolved in EC / EMC / DMC with a volume ratio of 3:4:3), cathode sheet, and cathode shell, and a discharge test was performed at 25°C and 1C.

[0044] In addition, the CF of the above comparative example 1 is used x (x=0.9) to prepare the positive electrode material of the lithium / carbon fluoride primary battery, and assemble it into a lithium / carbon fluoride primary battery to test its performance, the steps are as follows:

[0045] (1)CF x (x=0.9), conductive agent (super p), binder (polyvinylidene fluoride), and solvent (N-methylpyrrolidone) were mixed at a mass ratio of 8:1:1:9 for 30 minutes to obtain a uniform slurry. The slurry was evenly coated on aluminum foil with a scraper with a thickness of 100μL, dried at 70℃ for 2h, and then cut into circular positive electrode sheets with a diameter of 10mm, and continued to dry at 100℃ for 12h.

[0046] (2) In an argon atmosphere glove box, a 2032-type button cell was assembled in the order of anode shell, spring sheet, stainless steel gasket, metal lithium sheet, diaphragm, electrolyte (1 mol / L LiPF6 dissolved in EC / EMC / DMC with a volume ratio of 3:4:3), cathode sheet, and cathode shell, and a discharge test was performed at 25°C and 1C.

[0047] The button cells assembled with Example 1 and Comparative Example 1 as positive electrode materials were discharged at different current densities, and the discharge cut-off voltage was set to 1.5V (vs. Li / Li + ).

[0048] Comparative Example 1 CF x The discharge curve of the lithium / carbon fluoride primary battery assembled as the positive electrode material is as follows Figure 5 As shown, at a current density of 3000mAg -1 When CF x The positive electrode cannot discharge effectively.

[0049] With the CF of Example 1 of the present invention x The discharge curve of the lithium / carbon fluoride primary battery assembled with the / Mn5O8 composite material as the positive electrode material is shown in Figure 6 As shown, at a current density of 3000mAg -1 When CF x The specific capacity of the Mn5O8 positive electrode is 505 mAh g -1 , and the specific capacity and voltage platform at high current density are higher than Figure 5 CF x This is because, on the one hand, the network structure formed by rod-shaped Mn5O8 on the surface of carbon fluoride can not only improve the CF x The electron conduction of the positive electrode, and its large specific surface area can provide more electrochemical active sites, thereby improving the high current discharge performance of lithium / carbon fluoride primary batteries; on the other hand, Mn5O8 has a unique crystal structure (interlayer and / or intralayer defects) and cationic valence characteristics (mixed valence cations), and it also has good lithium storage performance, and its cost is lower than CF x Lower, as a composite component it helps to increase CF x electrochemical performance while reducing its cost.

[0050] Although the preferred embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments, which are merely illustrative and not restrictive. Under the guidance of the present invention, a person skilled in the art can make many forms without departing from the scope of protection of the present invention and the claims. All of these belong to the protection scope of the present invention.

Claims

1. A kind of CF x / Mn5O8 composite positive electrode material synthesis method, the CF x / Mn5O8 composite positive electrode material is suitable for lithium-carbon fluoride primary battery, characterized in that: CF x With manganese source as raw material, CF x The precursor material with rod-like MnOOH grown on the surface is then calcined in an oxygen atmosphere to obtain CF x / Mn5O8 composite materials; The following steps are involved: CF was added in a mass ratio of 9:0.25–2. x The mixture was dispersed in deionized water with an emulsifier and stirred evenly; a high-valent manganese source and a low-valent manganese source were added in a molar ratio of 3:1-2 and stirred evenly; the mixture was transferred to a hydrothermal reactor and heated at 150-220°C for hydrothermal synthesis, and then cooled to room temperature; the obtained product was washed and dried to obtain rod-shaped MnOOH grown on CF x The precursor material on the surface is further calcined at 250–400 °C in an oxygen atmosphere to obtain rod-shaped Mn5O8 grown on CF x Surface product composite material CF x / Mn5O8.

2. The CF according to claim 1 x / Mn5O8 composite positive electrode material synthesis method, characterized in that, CF x The fluorinated carbons have different fluorine contents, wherein x=0.6-1.2, and include at least one of fluorinated graphite, fluorinated graphene, and fluorinated carbon nanotubes.

3. The CF according to claim 1 x / Mn5O8 composite positive electrode material synthesis method, characterized in that, The emulsifier is at least one of the alkylphenol polyoxyethylene ether emulsifiers OP series, TX series, and NP series.

4. The CF according to claim 1 x / Mn5O8 composite positive electrode material synthesis method, characterized in that, CF x The mass ratio of manganese to high-valent manganese source is 3:0.25–2.

5. The CF according to claim 1 x / Mn5O8 composite positive electrode material synthesis method, characterized in that, The high-valent manganese source is one of potassium permanganate KMnO4 and potassium manganate K2MnO4, and the low-valent manganese source is one of manganese sulfate MnSO4, manganese nitrate Mn(NO3)2, and manganese chloride MnCl2.

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