FePcF 16 / Oxidized fruit residue carbon sulfur fixation material, preparation method, sulfur fixation method and lithium-sulfur battery cathode material

Abstract

The present invention discloses a FePcF 16 / oxidized fruit residue carbon sulfur fixation material and its preparation method, sulfur fixation method and lithium-sulfur battery cathode material, wherein: the preparation method of the sulfur fixation material includes the steps of: 1. preparing fruit residue carbon APC; 2. preparing oxidized fruit residue carbon OAPC; 3. preparing FePcF 16 / oxidized fruit residue carbon sulfur fixation material; the sulfur fixation method includes the steps of: mixing the FePcF 16 / oxidized fruit residue carbon sulfur fixation material with sublimed sulfur S8, grinding and then placing it in a hydrothermal reaction kettle, heating to 140-180 °C and keeping warm, and after naturally cooling to room temperature, obtaining the cathode material of the lithium-sulfur battery after sulfur fixation. The phthalocyanine containing an electron-withdrawing group in the present invention is combined with oxidized fruit residue carbon, showing excellent performance in anchoring and catalytic conversion of polysulfide lithium, improving its catalytic conversion efficiency and the utilization rate of active substance S, effectively inhibiting the occurrence of the shuttle effect, enabling the lithium-sulfur battery to exhibit stable cycling performance and high Coulomb efficiency under high current, and moreover, the preparation process is simple, has high repeatability and controllable morphology, which is beneficial to large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-sulfur batteries, and specifically relates to FePcF 16 / oxidized pomace carbon sulfur fixation materials, preparation methods, sulfur fixation methods, and lithium-sulfur battery cathode materials. Background Art

[0002] Currently, for commercially available lithium-ion secondary batteries, the cathode materials are usually some lithium intercalation compounds, such as: LiCoO2, LiNiO2, LiMnO2, LiFePO4, LiMnPO4, LiNiPO4, and LiMn2O4, etc. The actual specific capacity of these materials is relatively low, generally around 300 mAh g -1 . With the wide use of portable electronic devices and electric vehicles, higher requirements are put forward for energy storage devices. The existing commercially available lithium-ion batteries can no longer meet people's needs. Lithium-sulfur (Li-S) batteries have attracted extensive attention from researchers due to their extremely high theoretical energy density (2567 Wh.kg -1 ) and theoretical specific capacity (1675 mAh g -1 ). The positive active material sulfur has the advantages of rich reserves and low cost, which is very beneficial to the large-scale commercial production and application of Li-S batteries. Although Li-S batteries have great application potential, there are still many problems to be overcome, mainly reflected in: First, the conductivity of S and its discharge product Li2S is poor; Second, due to the different volume densities of elemental sulfur and the discharge product Li2S during the lithiation process, serious volume expansion will occur, about 80% or so; Third, the shuttle effect of polysulfide during charge and discharge, resulting in the loss of active substances. These problems will limit the development of lithium-sulfur batteries.

[0003] In response to the above problems, in recent years, researchers have extensively studied carbon materials with excellent electrical conductivity and adjustable pore structures to improve the rate performance of lithium-sulfur batteries. The pore structure can effectively relieve the volume expansion of the sulfur cathode while increasing the sulfur loading. However, the microporous structure of carbon materials is prone to blockage after long cycles, resulting in unstable cycle performance.

[0004] Transition metal phthalocyanine is a stable and efficient catalyst. The transition metal atom in its center can coordinate with the surrounding nitrogen atoms to form M-N4, which has high catalytic activity. Moreover, the transition metal phthalocyanine complex modified by peripheral substituents can effectively change the charge adsorption and transmission properties, and exhibits excellent ability in the catalytic conversion of lithium polysulfide. Therefore, there are currently two main methods to improve the catalytic performance of transition metal phthalocyanine: one is to improve its conjugation effect by modifying the peripheral substituents of phthalocyanine; the other most common method is to design nanoscale MPc to achieve the purpose of exposing more active specific surface area, but greater surface activity will cause MPc to agglomerate during the electrochemical reaction, and it cannot continuously exert the catalytic effect during the long cycle process. In addition, the electrical conductivity of MPc itself is not high, resulting in low electron utilization during the reaction process. Therefore, a suitable carbon material is needed as a carrier of transition metal phthalocyanine MPc. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a FePcF 16 / Oxidized pomace carbon sulfur-fixing material and preparation method, sulfur-fixing method and lithium-sulfur battery positive electrode material, which improve the structural stability, cycle performance and coulombic efficiency of the lithium-sulfur battery positive electrode under large current.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The preparation method of FePcF16 / oxidized pomace carbon sulfur-fixing material comprises the following steps:

[0008] Step 1: Preparation of pomace carbon APC

[0009] 0.5-1.5 g of pomace, 0.3-0.7 g of KOH and 30-70 mL of ultrapure water were added into a beaker and stirred evenly, and then transferred into a hydrothermal reactor, and kept at 150-200° C. for 20-30 h, and then cooled to obtain product A;

[0010] The product A is vacuum filtered to remove excess water, then dried and fully ground, then transferred to a porcelain boat and placed in a tube furnace, heated from room temperature to 500-800°C at a heating rate of 5-10°C / min under an argon atmosphere and calcined for 0.5-2h to obtain pomace carbon APC;

[0011] Step 2: Preparation of oxidized pomace carbon OAPC

[0012] Take 0.3-0.7g of pomace carbon and 0.2-0.5g of NaNO3 and dissolve them in 20-30mL of 98% concentrated sulfuric acid to obtain solution B. Let solution B stand in an ice bath, then heat it to 10°C, slowly add 2-5g of KMnO4 to solution B and stir to obtain solution C.

[0013] Solution C was heated to 35°C in a water bath for 2 hours, and 100-150 mL of deionized water was slowly added, and then the water bath was heated to 80°C and fully stirred, and then a 30% H2O2 solution was added dropwise to solution C until no bubbles were generated, and sample D was obtained by hot centrifugation, and sample D was first washed with HCl, and then washed with ultrapure water until neutral, and then dried to obtain oxidized pomace carbon OAPC;

[0014] Step 3: Preparation of FePcF 16 / Oxidized pomace carbon-fixing sulfur materials

[0015] Material F, urea, ammonium molybdate and ammonium ferrous sulfate hexahydrate were mixed according to a molar mass ratio of 50:(180-200):1:(15-25) to obtain a phthalocyanine raw material; oxidized pomace carbon OAPC was mixed with the phthalocyanine raw material according to a mass ratio of the phthalocyanine raw material to oxidized pomace carbon OAPC (7-20):10, and the oxidized pomace carbon OAPC was fully ground and placed in a tube furnace. In an argon atmosphere of 15 sccm, a two-step sintering method was adopted, and the temperature was raised from room temperature to 140-180°C at a heating rate of 5-10°C / min, and the temperature was kept for 30 minutes, and the temperature was further raised to 260-300°C for calcination for 1-5 hours to obtain a product E. The product E was first washed and filtered 3 times with ultrapure water and then washed and filtered 2 times with anhydrous ethanol, and dried to obtain FePcF 16 / Oxidized pomace carbon-fixing sulfur materials;

[0016] The substance F is any one of tetrafluorophthalic acid, tetrafluorophthalic anhydride or tetrafluorophthalimide.

[0017] Furthermore, the drying in step 1 is carried out at a constant temperature of 60 to 75° C. for 10 to 15 hours.

[0018] Furthermore, in step 1, the volume flow rate of argon gas is 15 to 30 sccm.

[0019] Furthermore, the standing time of step 2 is 20 to 50 minutes.

[0020] Furthermore, the stirring time of step 2 is 1 to 2 hours.

[0021] Furthermore, the drying in step 2 is performed in an oven at a constant temperature of 50 to 70° C. for 10 to 15 hours.

[0022] Further, the drying in step 3 is carried out in a forced-air drying oven at 60-75 °C for heat preservation for 10-20 h.

[0023] A kind of FePcF 16 / oxidized fruit residue carbon desulfurization material.

[0024] A kind of FePcF 16 The desulfurization method of the / oxidized fruit residue carbon desulfurization material includes the following steps:

[0025] Step 1: According to the mass ratio of 3:7 of the FePcF 16 / oxidized fruit residue carbon desulfurization material to sublimed sulfur S8, take 1.5-3.5 g of sublimed sulfur S8 and mix it with the FePcF 16 / oxidized fruit residue carbon desulfurization material, and grind it to obtain powder F;

[0026] Step 2: Place the powder F in a hydrothermal autoclave, heat it up to 140-180 °C and keep it warm for 20-30 h. After naturally cooling to room temperature, the sulfur-fixed lithium-sulfur battery cathode material is obtained.

[0027] A lithium-sulfur battery cathode material, at a current density of 3C, the initial discharge capacity is 920 mAh g -1 , after 500 cycles, the discharge capacity remains at 682 mAh g -1 .

[0028] Compared with the prior art, the present invention has the following technical effects:

[0029] The present invention uses industrial waste fruit residue as raw material, and prepares oxidized fruit residue carbon OAPC through simple etching, carbonization and oxidation processes. Among them, the oxidation process can generate a large number of defects on the surface of the fruit residue carbon material, functionalize it, increase the active sites, and promote the loading of FePcF 16 . The oxidized fruit residue carbon OAPC has a three-dimensional network pore structure with a large specific surface area. As the carrier of FePcF 16 , while improving the conductive characteristics, it induces the generation of nano-scale catalysts uniformly distributed on the surface of the oxidized fruit residue carbon, and exposes the active sites sufficiently, which can effectively relieve the volume expansion of the active substance sulfur during the working process of the lithium-sulfur battery and keep its pore structure stable. Adding iron phthalocyanine FePcF 16 modified by fluorine substituents, and using a simple in-situ method to combine FePcF 16 with the carbon material, effectively realizes the anchoring and conversion of polysulfide lithium, improves the catalytic conversion efficiency of polysulfide lithium and the utilization rate of the active substance S, effectively inhibits the occurrence of the shuttle effect, and makes the lithium-sulfur battery have an initial discharge capacity of 920 mAh g at a large current density of 3C 16 . -1After 500 cycles, the discharge capacity remains at 682 mAh g -1 . It can be seen that the lithium-sulfur battery cathode material prepared by the present invention has good conductivity, cycle stability, high discharge specific capacity and high Coulomb efficiency.

[0030] The present invention uses industrial waste fruit residue as a carbon source, which has sufficient sources and low costs. The obtained product has high repeatability and controllable morphology, not only conforms to the environmental protection concept, but also is more conducive to large-scale production and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the XRD pattern of the fruit residue carbon APC, oxidized fruit residue carbon OAPC and FePcF 16 / OAPC sulfur-fixing material prepared in Example 1 of the present invention;

[0032] Figure 2 is the SEM image of the FePcF 16 / OAPC sulfur-fixing material prepared in Example 1 of the present invention;

[0033] Figure 3 is the electrochemical characteristic diagram of the lithium-sulfur battery cathode material prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0034] The following further elaborates on the specific content of the present invention in conjunction with examples.

[0035] Example 1

[0036] FePcF 16 / OAPC sulfur-fixing material preparation method, including the following steps:

[0037] Step 1, preparation of fruit residue carbon APC

[0038] Add 1.5 g of fruit residue, 0.5 g of KOH and 30 mL of ultrapure water into a beaker, stir evenly, transfer to a hydrothermal reaction kettle with a capacity of 100 mL, keep warm at 150 °C for 25 h, and obtain product A after cooling;

[0039] Vacuum filter product A to remove excess moisture, dry it at a constant temperature of 60 °C in an oven for 13 h, then grind it thoroughly, then transfer it to a porcelain boat and place it in a tube furnace. Under an argon atmosphere of 15 sccm, heat it from room temperature to 500 °C at a heating rate of 7 °C / min and calcine for 1 h to obtain fruit residue carbon APC;

[0040] Step 2, preparation of oxidized fruit residue carbon OAPC

[0041] Take 0.4 g of fruit residue carbon and 0.3 g of NaNO3 and dissolve them in 20 mL of concentrated sulfuric acid with a mass fraction of 98% to obtain solution B. Let solution B stand for 30 min under an ice bath condition at 0 °C, then raise the temperature to 10 °C, slowly add 3 g of KMnO4 to solution B and stir for 2 h to obtain solution C;

[0042] Heat solution C to 35 °C in a water bath and keep it warm for 2 h, and slowly add 100 mL of deionized water. Then heat the water bath to 80 °C and stir well for 1.5 h. Next, add 30% H2O2 solution dropwise to solution C until no bubbles are generated. Centrifuge while it is hot to obtain sample D. Wash sample D first with 150 mL of HCl, then with ultrapure water until the pH value is 7, and dry it in an oven at 60 °C for 10 h to obtain oxidized fruit residue carbon OAPC;

[0043] Step 3: Prepare FePcF 16 / OAPC desulfurization material

[0044] Mix 50:180:1:15 of phthalic anhydride, urea, ammonium molybdate and ammonium ferrous sulfate hexahydrate according to the molar mass ratio to obtain phthalocyanine raw materials; according to the mass ratio of 7:10 of phthalocyanine raw materials to oxidized fruit residue carbon OAPC, take oxidized fruit residue carbon OAPC and phthalocyanine raw materials and mix them. After fully grinding, place them in a tube furnace. Under an argon atmosphere of 15 sccm, heat from room temperature to 150 °C at a heating rate of 7 °C / min and keep it warm for 30 min. Then continue to heat at a heating rate of 7 °C / min to 270 °C and calcine for 3 h to obtain product E. Wash product E with ultrapure water by suction filtration 3 times first, then wash with absolute ethanol by suction filtration 2 times. Next, keep it warm in a forced-air drying oven at 65 °C for 10 h to obtain FePcF 16 / OAPC desulfurization material.

[0045] FePcF 16 The desulfurization method of FePcF

[0046] Step 1: According to the mass ratio of FePcF 16 / OAPC desulfurization material to sublimed sulfur S8 of 3:7, take 1.5 g of sublimed sulfur S8 and mix it with FePcF 16 / OAPC desulfurization material, and grind to obtain powder F;

[0047] Step 2: Place powder F in a hydrothermal autoclave, heat it to 140 °C and keep it warm for 20 h. After natural cooling to room temperature, obtain the lithium-sulfur battery positive electrode material FePcF 16 / OAPC with desulfurization completed.

[0048] Consisting of Figure 1It can be seen from the XRD pattern that there is no obvious bread-like peak in the fruit residue carbon prepared in Example 1. Instead, it coincides with the PDF card of KHCO3, which is caused by the excess KOH after multiple etching processes. After acid treatment with concentrated sulfuric acid, the characteristic peak of KHCO3 in OAPC completely disappears, and the typical amorphous bread-like peak of graphite appears. In the FePcF 16 / OAPC desulfurization material, due to the existence of a large number of oxygen-containing functional groups on the surface of oxidized fruit residue carbon, FePcF16 grows along the crystal state on the surface of oxidized fruit residue carbon OAPC.

[0049] From Figure 2 the FePcF 16 / OAPC desulfurization material SEM image, it can be seen that nanoscale FePcF 16 particles grow densely on the surface of the OAPC carbon skeleton, and there is no obvious agglomeration.

[0050] The process of assembling a lithium-sulfur battery is as follows:

[0051] First, mix the sulfur-fixed lithium-sulfur battery cathode material FePcF 16 / OAPC, acetylene black, and PVDF in a mass ratio of 8:1:1, add an appropriate amount of NMP (N-methyl-2-pyrrolidone), stir into a slurry, coat it on aluminum foil, and vacuum dry it at 70 °C for 24 h, then stamp it into a battery cathode disc with a size of 12 mm. Then, select metallic lithium as the anode, use a CR 2032 type battery case, use Celgrad 2500 as the middle layer of the battery separator, the electrolyte is composed of 1.0 M lithium bis(trifluoromethanesulfonyl)imide LITFSI, the mixed solvent is DME / DOL (volume ratio 1:1), and the additive is 1.0% LiNO3. After assembling the lithium-sulfur battery, perform battery electrical performance tests;

[0052] From Figure 3 the electrochemical characteristic diagram of the lithium-sulfur battery cathode material FePcF 16 / OAPC, it can be seen that at a current density of 3C, the initial discharge capacity of the sulfur-fixed lithium-sulfur battery cathode material FePcF 16 / OAPC is 920 mAh g -1 . After 500 charge-discharge cycles, the capacity still remains at 682 mAh g -1 , and the capacity retention rate is 71.8%, and the attenuation rate per cycle is only 0.056%.

[0053] Example 2

[0054] FePcF 16 / OAPC desulfurization material preparation method, including the following steps:

[0055] Step 1, prepare fruit residue carbon APC

[0056] Add 0.8 g of fruit residue, 0.7 g of KOH, and 70 mL of ultrapure water into a beaker, stir evenly, transfer it into a hydrothermal reactor with a capacity of 150 mL, keep it warm at 170 °C for 25 h, and obtain product A after cooling;

[0057] Filter product A under vacuum to remove excess moisture, dry it at a constant temperature of 60 °C in an oven for 15 h, then grind it thoroughly, transfer it to a porcelain boat and place it in a tubular furnace. Under an argon atmosphere of 20 sccm, heat it from room temperature to 600 °C at a heating rate of 6 °C / min and calcine it for 1 h to obtain fruit residue carbon APC;

[0058] Step 2: Prepare oxidized fruit residue carbon OAPC

[0059] Take 0.5 g of fruit residue carbon and 0.3 g of NaNO3 and dissolve them in 30 mL of concentrated sulfuric acid with a mass fraction of 98%, obtain solution B. Let solution B stand still for 50 min under an ice bath condition of 0 °C, then raise the temperature to 10 °C, slowly add 3 g of KMnO4 to solution B and stir for 2 h to obtain solution C;

[0060] Heat solution C to 35 °C under a water bath condition and keep it warm for 2 h, slowly add 100 mL of deionized water, then heat the water bath to 80 °C and stir thoroughly for 1 h. Then, dropwise add a H2O2 solution with a mass fraction of 30% to solution C until no bubbles are generated. Centrifuge while it is hot to obtain sample D. Wash sample D first with 150 mL of HCl, then with ultrapure water until the pH value is 7, and dry it in an oven at 60 °C for 12 h to obtain oxidized fruit residue carbon OAPC;

[0061] Step 3: Prepare FePcF 16 / OAPC sulfur-fixing material

[0062] Take tetrafluorophthalic acid, urea, ammonium molybdate, and ammonium ferrous sulfate hexahydrate in a molar mass ratio of 50:190:1:20 and mix them to obtain phthalocyanine raw materials; take oxidized fruit residue carbon OAPC and phthalocyanine raw materials in a mass ratio of 14:10, mix oxidized fruit residue carbon OAPC and phthalocyanine raw materials, grind them thoroughly and place them in a tubular furnace. Under an argon atmosphere of 15 sccm, heat it from room temperature to 160 °C at a heating rate of 5 °C / min and keep it warm for 30 min, continue to heat it at a heating rate of 5 °C / min to 280 °C and calcine it for 4 h to obtain product E. Wash and filter product E 3 times with ultrapure water first, then wash and filter it 2 times with absolute ethanol, and then keep it warm at 60 °C in a forced-air drying oven for 15 h to obtain FePcF 16 / OAPC sulfur-fixing material.

[0063] FePcF 16 The sulfur-fixing method of FePcF

[0064] Step 1. According to the mass ratio of FePcF 16 / OAPC sulfur-fixing material to sublimed sulfur S8 of 3:7, take 2.5 g of sublimed sulfur S8 and mix it with FePcF 16 / OAPC sulfur-fixing material, and grind to obtain powder F;

[0065] Step 2. Place powder F in a hydrothermal autoclave, heat it to 155 °C and keep it warm for 24 h. After naturally cooling to room temperature, obtain the sulfur-fixed lithium-sulfur battery cathode material FePcF 16 / OAPC.

[0066] Example 3

[0067] Preparation method of FePcF 16 / OAPC sulfur-fixing material, including the following steps:

[0068] Step 1. Prepare fruit residue carbon APC

[0069] Add 1 g of fruit residue, 0.6 g of KOH and 50 mL of ultrapure water into a beaker, stir evenly, transfer it into a hydrothermal reaction kettle with a capacity of 200 mL, keep it warm at 200 °C for 20 h, and obtain product A after cooling;

[0070] Filter product A by vacuum filtration to remove excess water, dry it at a constant temperature of 70 °C in an oven for 12 h, then grind it thoroughly, then transfer it to a porcelain boat and place it in a tube furnace. Under an argon atmosphere of 25 sccm, heat it from room temperature to 700 °C at a heating rate of 9 °C / min and calcine for 0.5 h to obtain fruit residue carbon APC;

[0071] Step 2. Prepare oxidized fruit residue carbon OAPC

[0072] Take 0.3 g of fruit residue carbon and 0.2 g of NaNO3 and dissolve them in 20 mL of concentrated sulfuric acid with a mass fraction of 98%, obtain solution B, let solution B stand still for 20 min under an ice bath condition of 0 °C, then heat it to 10 °C, slowly add 2 g of KMnO4 to solution B and stir for 1 h to obtain solution C;

[0073] Heat solution C to 35 °C in a water bath and keep it warm for 1 h, slowly add 125 mL of deionized water, then heat the water bath to 80 °C and stir thoroughly for 2 h, then add a 30% H2O2 solution to solution C drop by drop until no bubbles are generated, centrifuge while it is hot to obtain sample D, wash sample D first with 250 mL of HCl, then with ultrapure water until the pH value is 7, and dry it in an oven at 50 °C for 15 h to obtain oxidized fruit residue carbon OAPC;

[0074] Step 3. Prepare FePcF 16 / OAPC sulfur-fixing materials

[0075] Tetrafluorophthalimide, urea, ammonium molybdate and ammonium ferrous sulfate hexahydrate were mixed according to a molar mass ratio of 50:200:1:25 to obtain a phthalocyanine raw material; according to a mass ratio of the phthalocyanine raw material to oxidized pomace carbon OAPC of 20:10, oxidized pomace carbon OAPC was mixed with the phthalocyanine raw material, fully ground and placed in a tube furnace, and heated from room temperature to 180°C at a heating rate of 9°C / min under an argon atmosphere of 15sccm for 30min, and then heated to 280°C at a heating rate of 9°C / min for calcination for 5h to obtain product E, and product E was first washed and filtered 3 times with ultrapure water, then washed and filtered 2 times with anhydrous ethanol, and then kept at 70°C in a blast drying oven for 12h to obtain FePcF 16 / OAPC sulfur-fixing material.

[0076] FePcF 16 / OAPC desulfurization material desulfurization method, comprising the following steps:

[0077] Step 1: According to FePcF 16 The mass ratio of OAPC solid sulfur material to sublimated sulfur S8 is 3:7. Take 3.5g of sublimated sulfur S8 and FePcF 16 / OAPC sulfur-fixing materials are mixed and ground to obtain powder F;

[0078] Step 2: Powder F is placed in a hydrothermal reactor, heated to 170°C and kept warm for 28 hours. After cooling naturally to room temperature, the solid sulfur lithium-sulfur battery positive electrode material FePcF is obtained. 16 / OAPC.

[0079] Example 4

[0080] FePcF 16 / OAPC sulfur-fixing material preparation method, comprising the following steps:

[0081] Step 1: Preparation of pomace carbon APC

[0082] 0.5 g of pomace, 0.3 g of KOH and 40 mL of ultrapure water were added into a beaker and stirred evenly, then transferred into a hydrothermal reactor with a capacity of 150 mL, and kept at 160°C for 23 h. Product A was obtained after cooling;

[0083] The product A was vacuum filtered to remove excess water, dried in an oven at 75°C for 10 h, and then fully ground, and then transferred to a porcelain boat and placed in a tube furnace. In an argon atmosphere of 15 sccm, the temperature was increased from room temperature to 800°C at a heating rate of 8°C / min and calcined for 1.5 h to obtain pomace carbon APC;

[0084] Step 2: Preparation of oxidized pomace carbon OAPC

[0085] 0.6 g of pomace carbon and 0.4 g of NaNO3 were dissolved in 25 mL of 98% concentrated sulfuric acid to obtain solution B. Solution B was placed in an ice bath at 0°C for 40 min, then heated to 10°C, 4 g of KMnO4 was slowly added to solution B and stirred for 1.5 h to obtain solution C.

[0086] Solution C was heated to 35°C in a water bath for 1.5h, and 150mL of deionized water was slowly added, and then the water bath was heated to 80°C and fully stirred for 1.5h, and then a 30% H2O2 solution was added dropwise to solution C until no bubbles were generated, and sample D was obtained by hot centrifugation, and sample D was first washed with 300mL of HCl, and then washed with ultrapure water until the pH value was 7, and dried in an oven at 65°C for 13h to obtain oxidized pomace carbon OAPC;

[0087] Step 3: Preparation of FePcF 16 / OAPC sulfur-fixing materials

[0088] Tetrafluorophthalimide, urea, ammonium molybdate and ammonium ferrous sulfate hexahydrate were mixed in a molar mass ratio of 50:185:1:18 to obtain a phthalocyanine raw material; oxidized pomace carbon OAPC was mixed with the phthalocyanine raw material in a mass ratio of 10:10 to the phthalocyanine raw material, and the phthalocyanine raw material was fully ground and placed in a tube furnace. In an argon atmosphere of 15 sccm, the temperature was increased from room temperature to 180°C at a heating rate of 6°C / min and kept for 30 min, and then the temperature was increased to 290°C at a heating rate of 6°C / min and calcined for 3 h to obtain product E. The product E was first washed and filtered 3 times with ultrapure water, then washed and filtered 2 times with anhydrous ethanol, and then kept at 75°C in a blast drying oven for 18 h to obtain FePcF 16 / OAPC sulfur-fixing material.

[0089] FePcF 16 / OAPC desulfurization material desulfurization method, comprising the following steps:

[0090] Step 1: According to FePcF 16 / OAPC solid sulfur material and sublimated sulfur S8 mass ratio is 3:7, take 2.5g sublimated sulfur S8 and FePcF 16 / OAPC sulfur-fixing materials are mixed and ground to obtain powder F;

[0091] Step 2: Powder F is placed in a hydrothermal reactor, heated to 160°C and kept warm for 25 hours. After cooling naturally to room temperature, the solid sulfur lithium-sulfur battery positive electrode material FePcF is obtained. 16 / OAPC.

[0092] Example 5

[0093] FePcF 16 / OAPC sulfur-fixing material preparation method, comprising the following steps:

[0094] Step 1: Preparation of pomace carbon APC

[0095] 1.2 g of pomace, 0.4 g of KOH and 60 mL of ultrapure water were added into a beaker and stirred evenly, then transferred into a hydrothermal reactor with a capacity of 200 mL, kept at 180°C for 28 h, and cooled to obtain product A;

[0096] The product A was vacuum filtered to remove excess water, dried in an oven at 65°C for 14 h, then fully ground, transferred to a porcelain boat and placed in a tube furnace, heated from room temperature to 550°C at a heating rate of 5°C / min in an argon atmosphere of 20 sccm and calcined for 0.5 h to obtain pomace carbon APC;

[0097] Step 2: Preparation of oxidized pomace carbon OAPC

[0098] Take 0.7g of pomace carbon and 0.5g of NaNO3 and dissolve them in 30mL of 98% concentrated sulfuric acid to obtain solution B. Place solution B in an ice bath at 0°C for 50min, then heat it to 10°C, slowly add 5g of KMnO4 to solution B and stir for 1h to obtain solution C.

[0099] Solution C was heated to 35°C in a water bath for 2 hours, and 150 mL of deionized water was slowly added, and then the water bath was heated to 80°C and fully stirred for 2 hours, and then a 30% H2O2 solution was added dropwise to solution C until no bubbles were generated, and sample D was obtained by hot centrifugation, and sample D was first washed with 150 mL of HCl, and then washed with ultrapure water until the pH value was 7, and dried in an oven at 70°C for 14 hours to obtain oxidized pomace carbon OAPC;

[0100] Step 3: Preparation of FePcF 16 / OAPC sulfur-fixing materials

[0101] Take tetrafluorophthalic acid, urea, ammonium molybdate and ammonium ferrous sulfate hexahydrate in a molar mass ratio of 50:195:1:22 and mix them to obtain a phthalocyanine raw material; take oxidized fruit residue carbon OAPC and the phthalocyanine raw material in a mass ratio of 17:10, mix the oxidized fruit residue carbon OAPC and the phthalocyanine raw material, fully grind them and then place them in a tube furnace. Under an argon atmosphere of 15 sccm, heat from room temperature to 150 °C at a heating rate of 8 °C / min and keep warm for 30 min, then continue to heat to 300 °C at a heating rate of 8 °C / min and calcine for 1 h to obtain product E. Wash product E with ultrapure water by suction filtration 3 times, then wash with absolute ethanol by suction filtration 2 times, and then keep warm in a forced-air drying oven at 60 °C for 20 h to obtain FePcF 16 / OAPC sulfur fixation material.

[0102] FePcF 16 A sulfur fixation method for FePcF

[0103] Step 1. According to the mass ratio of FePcF 16 / OAPC sulfur fixation material to sublimed sulfur S8 of 3:7, take 2 g of sublimed sulfur S8 and mix it with FePcF 16 / OAPC sulfur fixation material, and grind to obtain powder F;

[0104] Step 2. Place powder F in a hydrothermal autoclave, heat to 175 °C and keep warm for 22 h. After natural cooling to room temperature, obtain the sulfur-fixed lithium-sulfur battery cathode material FePcF 16 / OAPC.

[0105] Example 6

[0106] FePcF 16 A preparation method for FePcF

[0107] Step 1. Prepare fruit residue carbon APC

[0108] Add 1 g of fruit residue, 0.5 g of KOH and 70 mL of ultrapure water to a beaker, stir evenly, transfer to a hydrothermal reaction kettle with a capacity of 200 mL, keep warm at 190 °C for 30 h, and obtain product A after cooling;

[0109] Filter product A by vacuum suction to remove excess water, dry it at a constant temperature of 75 °C in an oven for 11 h, then fully grind it, and then transfer it to a porcelain boat and place it in a tube furnace. Under an argon atmosphere of 30 sccm, heat from room temperature to 650 °C at a heating rate of 10 °C / min and calcine for 2 h to obtain fruit residue carbon APC;

[0110] Step 2. Prepare oxidized fruit residue carbon OAPC

[0111] Take 0.5 g of fruit residue carbon and 0.35 g of NaNO3 and dissolve them in 30 mL of concentrated sulfuric acid with a mass fraction of 98% to obtain solution B. Let solution B stand for 20 min under an ice bath condition at 0 °C, then raise the temperature to 10 °C, slowly add 3.5 g of KMnO4 to solution B and stir for 1.5 h to obtain solution C;

[0112] Heat solution C to 35 °C under a water bath condition and keep it warm for 1.5 h, and slowly add 100 mL of deionized water. Then heat the water bath to 80 °C and stir well for 1 h. Next, add a 30% H2O2 solution dropwise to solution C until no bubbles are generated. Centrifuge while it is hot to obtain sample D. Wash sample D first with 200 mL of HCl, and then wash it with ultrapure water until the pH value is 7. Dry it in an oven at 55 °C for 15 h to obtain oxidized fruit residue carbon OAPC;

[0113] Step 3: Prepare FePcF 16 / OAPC desulfurization material

[0114] Take tetrafluorophthalic anhydride, urea, ammonium molybdate and ammonium ferrous sulfate hexahydrate in a molar mass ratio of 50:180:1:15 and mix them to obtain phthalocyanine raw materials; take oxidized fruit residue carbon OAPC and phthalocyanine raw materials in a mass ratio of 12:10 for the phthalocyanine raw materials and oxidized fruit residue carbon OAPC. After fully grinding, place them in a tubular furnace. Under an argon atmosphere of 15 sccm, heat from room temperature to 140 °C at a heating rate of 10 °C / min and keep it warm for 30 min. Then continue to heat at a heating rate of 10 °C / min to 260 °C and calcine for 2 h to obtain product E. Wash and filter product E with ultrapure water 3 times first, then wash and filter it with absolute ethanol 2 times. Next, keep it warm in a forced-air drying oven at 75 °C for 10 h to obtain FePcF 16 / OAPC desulfurization material.

[0115] FePcF 16 The desulfurization method of FePcF

[0116] Step 1: According to the mass ratio of FePcF 16 / OAPC desulfurization material to sublimed sulfur S8 of 3:7, take 3 g of sublimed sulfur S8 and mix it with FePcF 16 / OAPC desulfurization material, and grind to obtain powder F;

[0117] Step 2: Place powder F in a hydrothermal autoclave, raise the temperature to 180 °C and keep it warm for 30 h. After natural cooling to room temperature, obtain the lithium-sulfur battery positive electrode material FePcF 16 / OAPC with completed desulfurization.

[0118] The FePcF prepared in Examples 1 to 6 of the present invention 16 / FePcF in the oxidized fruit residue carbon sulfur-fixing material 16 It can also be replaced by tetrafluorosubstituted iron phthalocyanine, octafluorosubstituted iron phthalocyanine, tetraaminophthalocyanine iron, tetrahydroxyphthalocyanine iron, tetranitrophthalocyanine iron or tetramethylphthalocyanine iron, and the Fe atom of iron phthalocyanine can also be replaced by transition metals such as Zn, Mn or Co.

Claims

1. FePcF 16 / Preparation method of oxidized fruit residue carbon sulfur-fixing material, characterized in that The steps include: Step 1: Preparation of pomace carbon APC 0.5-1.5 g of pomace, 0.3-0.7 g of KOH and 30-70 mL of ultrapure water were added into a beaker and stirred evenly, and then transferred into a hydrothermal reactor, and kept at 150-200° C. for 20-30 h, and then cooled to obtain product A; The product A is vacuum filtered to remove excess water, then dried and fully ground, then transferred to a porcelain boat and placed in a tube furnace, heated from room temperature to 500-800°C at a heating rate of 5-10°C / min under an argon atmosphere and calcined for 0.5-2h to obtain pomace carbon APC; Step 2: Preparation of oxidized pomace carbon OAPC 0.3-0.7 g of pomace carbon and 0.2-0.5 g of NaNO3 are dissolved in 20-30 mL of 98% concentrated sulfuric acid to obtain solution B. Solution B is allowed to stand in an ice bath, then heated to 10°C, 2-5 g of KMnO4 is slowly added to solution B and stirred to obtain solution C. Solution C was heated to 35°C in a water bath for 2 hours, and 100-150 mL of deionized water was slowly added, and then the water bath was heated to 80°C and fully stirred, and then a 30% H2O2 solution was added dropwise to solution C until no bubbles were generated, and sample D was obtained by hot centrifugation, and sample D was first washed with HCl, and then washed with ultrapure water until neutral, and then dried to obtain oxidized pomace carbon OAPC; Step 3: Prepare FePcF 16 / oxidized fruit residue carbon desulfurization material Take substances F, urea, ammonium molybdate, and ammonium ferrous sulfate hexahydrate in a molar mass ratio of 50:(180 - 200):1:(15 - 25) and mix them to obtain the phthalocyanine raw material; take the oxidized fruit residue carbon OAPC and the phthalocyanine raw material in a mass ratio of (7 - 20):10, mix the oxidized fruit residue carbon OAPC and the phthalocyanine raw material, fully grind them, and place them in a tube furnace. Under an argon atmosphere of 15 sccm, heat from room temperature to 140 - 180 °C at a heating rate of 5 - 10 °C / min and hold for 30 min, then continue to heat to 260 - 300 °C at a heating rate of 5 - 10 °C / min and calcine for 1 - 5 h to obtain product E. Wash product E successively with ultrapure water and absolute ethanol, and dry to obtain FePcF 16 / oxidized fruit residue carbon sulfur-fixing material; The substance F is any one of tetrafluorophthalic acid, tetrafluorophthalic anhydride or tetrafluorophthalimide.

2. The FePcF according to claim 1 16 / Preparation method of oxidation fruit residue carbon desulfurization material, characterized in that The drying in step 1 is carried out at a constant temperature of 60 to 75° C. for 10 to 15 hours.

3. The FePcF according to claim 1 16 / Preparation method of an oxidized fruit residue carbon sulfur-fixing material, characterized in that The volume flow rate of argon gas in step 1 is 15-30 sccm.

4. The FePcF according to claim 1 16 / Preparation method of an oxidized fruit residue carbon sulfur-fixing material, characterized in that The standing time of step 2 is 20 to 50 minutes.

5. The FePcF according to claim 1 16 / Preparation method of oxidized fruit residue carbon desulfurization material, characterized in that The stirring time of step 2 is 1 to 2 hours.

6. The FePcF according to claim 1 16 / Preparation method of oxidized fruit residue carbon desulfurization material, characterized in that The drying in step 2 is carried out in an oven at a constant temperature of 50 to 70° C. for 10 to 15 hours.

7. The FePcF according to claim 1 16 / Preparation method of oxidized fruit residue carbon sulfur-fixing material, characterized in that The drying in step 3 is carried out by using a forced air drying oven at 60-75° C. for 10-20 hours.

8. An FePcF / oxidized fruit residue carbon sulfur fixation material prepared by the method according to any one of claims 1 to 7 16 ​ 9. A FePcF as described in claim 8 16 / desulfurization method of the oxidation residue carbon desulfurization material, characterized in that The steps include: Step 1. According to the mass ratio of FePcF 16 / oxidized fruit residue carbon desulfurization material to sublimed sulfur S8 of 3:7, take 1.5 - 3.5 g of sublimed sulfur S8 and mix it with FePcF 16 / oxidized fruit residue carbon desulfurization material, and grind to obtain powder F; Step 2: Place the powder F in a hydrothermal reactor, heat it to 140-180° C. and keep it warm for 20-30 hours. After cooling naturally to room temperature, a solid sulfur lithium-sulfur battery positive electrode material is obtained.

10. A lithium-sulfur battery cathode material prepared by the sulfur fixation method according to claim 9, characterized in that, At a current density of 3C, the initial discharge capacity is 920 mAh g -1 , and after 500 cycles, the discharge capacity remains at 682 mAh g -1 .

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