WO2024000873A1 - 复合隔膜及其制备方法和含有其的锂硫电池 - Google Patents

复合隔膜及其制备方法和含有其的锂硫电池 Download PDF

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WO2024000873A1
WO2024000873A1 PCT/CN2022/121937 CN2022121937W WO2024000873A1 WO 2024000873 A1 WO2024000873 A1 WO 2024000873A1 CN 2022121937 W CN2022121937 W CN 2022121937W WO 2024000873 A1 WO2024000873 A1 WO 2024000873A1
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molecular sieve
lithium
cobalt
composite separator
weight
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PCT/CN2022/121937
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English (en)
French (fr)
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杨为民
王小飞
蓝大为
李骏
王振东
薛浩亮
张道明
周思飞
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中国石油化工股份有限公司
中国石油化工股份有限公司上海石油化工研究院
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Priority claimed from CN202210742846.7A external-priority patent/CN117352958A/zh
Priority claimed from CN202210742774.6A external-priority patent/CN117352949A/zh
Application filed by 中国石油化工股份有限公司, 中国石油化工股份有限公司上海石油化工研究院 filed Critical 中国石油化工股份有限公司
Publication of WO2024000873A1 publication Critical patent/WO2024000873A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • the present invention relates to the field of battery separators, and in particular to a composite separator, a preparation method thereof, and a lithium-sulfur battery containing the same.
  • Lithium-sulfur batteries have high theoretical specific capacity (1675mAh/g) and theoretical energy density (2600Wh/kg). They are promising alternatives to lithium-ion batteries and have become the focus of research on the next generation of high-specific-energy secondary batteries.
  • its cathode material active material sulfur also has the advantages of abundant natural resources, low price and environmental friendliness.
  • the shuttle effect means that lithium-sulfur batteries will produce a series of sulfur-containing intermediate products during the charge and discharge process, among which long-chain polysulfides (Li 2 S x , 2 ⁇ x ⁇ 8) are easily soluble in the electrolyte, and Under the action of concentration gradient and electric field, chemical side reactions occur between the separator and the lithium anode, causing the loss of active materials and an increase in the internal resistance of the battery, resulting in a reduction in battery capacity and cycle performance.
  • long-chain polysulfides Li 2 S x , 2 ⁇ x ⁇ 8
  • the electrochemical reaction process of lithium-sulfur batteries involves multi-step solid-liquid conversion, and the electronic conductivity of sulfur and the final discharge product lithium sulfide is poor. Therefore, the polysulfide conversion reaction kinetics is slow and the battery rate performance is poor.
  • molecular sieves to modify conventional separators to inhibit the shuttle effect of lithium-sulfur batteries, such as CN107546356A and CN103490027A. They utilize the physical barrier effect of molecular sieves such as ZSM-5, SAPO-34, 3A, and 13X to limit the migration and diffusion of Li 2 S x in the electrolyte to a certain extent, thereby improving battery performance.
  • the purpose of the present invention is to overcome the problems of poor battery rate performance, low battery capacity and poor cycle performance existing in the prior art.
  • the inventors of the present invention have found that by using molecular sieves containing cobalt and optional lithium for lithium-sulfur battery separators, the performance of the battery can be further improved, thereby meeting the above-mentioned needs of the prior art.
  • a composite membrane is provided comprising a composite layer of molecular sieves containing cobalt and optionally lithium.
  • the composite separator of the present invention can improve the rate performance and cycle stability of the battery.
  • the invention also provides a method for preparing the composite separator and a lithium-sulfur battery containing the composite separator.
  • a first aspect of the present invention provides a composite separator, which includes a polymer matrix film and a composite layer distributed on the surface of the polymer matrix film, wherein the composite layer includes a molecular sieve and a conductive carbon material, wherein the molecular sieve contains cobalt.
  • a second aspect of the present invention provides a method for preparing the composite separator, which method includes:
  • the present invention provides an application of the composite separator in a lithium-sulfur battery.
  • a fourth aspect of the present invention provides a lithium-sulfur battery, which includes a positive electrode, a negative electrode and the above composite separator located between the positive electrode and the negative electrode.
  • the present invention can be embodied in the following items:
  • a molecular sieve modified separator characterized in that the separator includes a polymer matrix film and a cobalt-doped molecular sieve/conductive carbon material composite layer distributed on the surface of the polymer matrix film.
  • the thickness of the cobalt-doped molecular sieve/conductive carbon material composite layer is 5-50 ⁇ m, preferably 10-40 ⁇ m; and/or
  • the mass ratio of the conductive carbon material to the cobalt-doped molecular sieve is 1:(1-9), preferably 1:(2-9).
  • the cobalt-doped molecular sieve has a chemical composition as shown in the formula "aCo ⁇ bM 2 O ⁇ ySiO 2 ⁇ zAl 2 O 3 ".
  • the cobalt-doped molecular sieve is selected from MFI, MWW, GIS, BEC, FAU and MOR. At least one of them, more preferably the cobalt-doped molecular sieve is at least one of MFI, MWW and GIS;
  • M is an alkali metal element of Group IA, preferably one or more of Na, K, and Li;
  • the cobalt-doped molecular sieve is a cobalt-doped lithiated molecular sieve
  • the cobalt-doped lithiated molecular sieve has a chemical composition as shown in the formula "aCo ⁇ bLi 2 O ⁇ ySiO 2 ⁇ zAl 2 O 3 ", wherein, 0.02 ⁇ a/y ⁇ 0.2, 0.01 ⁇ b/y ⁇ 0.2, 10 ⁇ y/z ⁇ 50.
  • the material of the polymer matrix film is at least one of polyethylene, polypropylene, polyimide, polyacrylonitrile, polyethylene terephthalate, polytetrafluoroethylene and polyvinylidene fluoride, preferably be polyethylene and/or polypropylene; and/or
  • the conductive carbon material is at least one of graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, carbon nanofibers, acetylene black, Super P and Ketjen black, preferably graphene, graphene oxide and At least one of the graphene oxides is reduced.
  • the preparation method of cobalt-doped molecular sieve includes: adding cobalt ion solution to Na-type molecular sieve, drying and reducing, to obtain cobalt-doped molecular sieve;
  • the cobalt-doped molecular sieve is a cobalt-doped lithiated molecular sieve, and the preparation method includes:
  • the lithium ion solution in S1 is at least one of a lithium chloride solution, a lithium sulfate solution, and a lithium nitrate solution;
  • the exchange conditions in S1 include: the temperature is 40-100°C, and the liquid-solid ratio is 10-50;
  • the Na-type molecular sieve has a chemical composition represented by “bNa 2 O ⁇ ySiO 2 ⁇ zAl 2 O 3 ”, where 0.01 ⁇ b/y ⁇ 0.2, 10 ⁇ y/z ⁇ 50; preferably, the Na-type molecular sieve has The topology structure is selected from at least one of MFI, MWW, GIS, BEC, FAU and MOR;
  • the cobalt ion solution is at least one of cobalt chloride solution, cobalt nitrate solution, cobalt sulfate solution, and cobalt acetate solution;
  • the conditions for the reduction include: the reduction atmosphere is a hydrogen atmosphere, the reduction temperature is 600-750°C, and the reduction time is 1-4 hours.
  • step (2) is selected from deionized water, absolute ethanol, N,N-dimethylacetamide, N,N-dimethylform At least one of amide, dimethyl sulfoxide and N-methylpyrrolidone, preferably N-methylpyrrolidone.
  • step (2) is polyvinyl alcohol, carboxymethylcellulose, polyvinylidene fluoride, polytetrafluoroethylene, poly At least one of vinylpyrrolidone, styrene-butadiene rubber and polyacrylate is preferably polyvinylidene fluoride.
  • the coating method in step (3) is at least one of a casting method, a blade coating method, a spray coating method, and a spin coating method, and is preferably a blade coating method.
  • the present invention can also be embodied in the following items:
  • a lithiated molecular sieve modified separator characterized in that the separator includes a lithiated molecular sieve/conductive carbon material composite layer and a polymer matrix film; the lithiated molecular sieve/conductive carbon material composite layer is distributed in the polymer matrix membrane surface.
  • At least one of a lithiated MOR type molecular sieve and a lithiated MOR type molecular sieve is preferably at least one of a lithiated MFI type molecular sieve, a lithiated MWW type molecular sieve and a lithiated GIS type molecular sieve.
  • lithiated molecular sieve modified separator according to any one of items 1 to 3, wherein the thickness of the lithiated molecular sieve/conductive carbon material composite layer is 2-40 ⁇ m, preferably 5-25 ⁇ m.
  • the mass ratio of the conductive carbon material to the lithiated molecular sieve is 1: (1-9), preferably 1: (2-9); and/or
  • the lithiated molecular sieve has a chemical composition represented by the formula “xLi 2 O ⁇ ySiO 2 ⁇ zAl 2 O 3 ”, where 0.01 ⁇ x/y ⁇ 0.2, 10 ⁇ y/z ⁇ 50.
  • lithiated molecular sieve modified separator described in any one of items 1 to 5, wherein the conductive carbon material is graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, carbon nanofibers, acetylene At least one of black, Super P, and Ketjen Black, preferably at least one of graphene, graphene oxide, and reduced graphene oxide.
  • step (2)
  • the solvent is at least one of deionized water, absolute ethanol, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, preferably is N-methylpyrrolidone; and/or,
  • the binder is at least one of polyvinyl alcohol, polytetrafluoroethylene, polyvinylpyrrolidone, carboxymethylcellulose, styrene-butadiene rubber, polyvinylidene fluoride, and polyacrylate, preferably polyvinylidene fluoride;
  • the coating method in step (3) is at least one of a casting method, a blade coating method, a spray coating method, and a spin coating method, and is preferably a blade coating method;
  • the preparation method of the lithiated molecular sieve includes: exchanging the Na-type molecular sieve with the lithium ion solution, washing, and drying to obtain the Li-type molecular sieve;
  • the Na-type molecular sieve has the chemical composition shown as "xNa 2 O ⁇ ySiO 2 ⁇ zAl 2 O 3 ", where 0.01 ⁇ x/y ⁇ 0.2, 10 ⁇ y/z ⁇ 50; preferably the Na-type molecular sieve From at least one of MFI molecular sieve, MWW molecular sieve, GIS molecular sieve, BEC molecular sieve, FAU molecular sieve and MOR molecular sieve;
  • the lithium ion solution is selected from at least one of lithium chloride solution, lithium sulfate solution, and lithium nitrate solution;
  • the exchange conditions include: the temperature is 40-100°C, and the liquid-to-solid ratio is 10-50.
  • a lithium-sulfur battery characterized in that the lithium-sulfur battery includes: a positive electrode shell, a positive electrode sheet, a separator, a lithium sheet, a nickel foam, and a negative electrode shell, and the separator is any one of items 1-6.
  • the lithiated molecular sieve modified separator is any one of items 1-6.
  • the preparation process of the composite separator of the present invention is simple and has little impact on the energy density of the battery;
  • the composite separator of the present invention contains a molecular sieve containing cobalt and optionally lithium in the composite layer.
  • the pore structure of the molecular sieve can effectively limit the migration and diffusion of Li 2 S x through physical barriers and reduce side reactions inside the battery.
  • the molecular sieve of the present invention contains cobalt, and the introduced cobalt can not only improve the conductivity of the positive electrode side of the separator, but also serve as an active site to enhance the conversion reaction kinetics of polysulfides.
  • the molecular sieve further contains lithium, the introduced lithium can provide a large number of sites for the adsorption and transmission of lithium ions during battery cycles, improving the lithium ion transmission performance of the separator. More importantly, when the molecular sieve contains lithium and cobalt, a synergistic effect is achieved in the resulting composite separator, which can greatly improve the rate performance and cycle stability of lithium-sulfur batteries.
  • Figure 1 is a scanning electron microscope picture of the composite separator obtained in Example 2-1;
  • Figure 2 shows the charge and discharge curves of the lithium-sulfur battery sample obtained in Example 2-1 at different current densities.
  • the present invention provides a composite separator, which includes a polymer matrix film and a composite layer distributed on the surface of the polymer matrix film, wherein the composite layer contains a molecular sieve and a conductive carbon material, and the molecular sieve contains cobalt.
  • the amount of cobalt in the molecular sieve is 1-30% by weight, preferably 1-15% by weight, more preferably 2-7% by weight, calculated as elemental cobalt, based on the total weight of cobalt and molecular sieve.
  • the molecular sieve further contains lithium, preferably the amount of lithium in the molecular sieve is 0.1-5% by weight, preferably 0.2-3% by weight, more preferably 0.5-2.5% by weight, calculated as lithium ions, based on lithium and the total weight of molecular sieves.
  • the molecular sieve has a topology selected from at least one of MFI, MWW, GIS, BEC, FAU and MOR, preferably at least one topology selected from MFI, MWW and GIS.
  • the present invention has no limitation on the thickness of the composite layer.
  • the thickness of the composite layer is 5-50 ⁇ m, preferably 10-40 ⁇ m.
  • the present invention has no limit on the mass ratio of the conductive carbon material to the molecular sieve in the composite layer.
  • the mass ratio of the conductive carbon material to the molecular sieve is 1:(1-9), preferably 1:(2-9), for example, it can be 1:1, 1:2, 1:4, 1:6, 1:8, 1:9.
  • the material of the polymer matrix film may be conventional materials in the art.
  • the polymer matrix film is made of polyethylene, polypropylene, polyimide, polyacrylonitrile, polyethylene terephthalate, polytetrafluoroethylene and polyvinylidene fluoride. At least one of them is preferably polyethylene and/or polypropylene.
  • the conductive carbon material may be a conventional material in the art.
  • the conductive carbon material is at least one of graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, carbon nanofibers, acetylene black, Super P and Ketjen black, preferably graphite At least one of ene, graphene oxide and reduced graphene oxide.
  • a second aspect of the present invention provides a method for preparing a composite separator, which method includes:
  • the amount of cobalt in the molecular sieve is 1-30% by weight, preferably 1-15% by weight, more preferably 2-7% by weight, calculated as elemental cobalt, based on the total weight of cobalt and molecular sieve.
  • the method further includes obtaining the molecular sieve as follows: adding a cobalt ion solution to the raw molecular sieve, and then drying and reducing the cobalt-containing molecular sieve.
  • the molecular sieve further contains lithium.
  • the amount of lithium in the molecular sieve is 0.1-5% by weight, preferably 0.2-3% by weight, more preferably 0.5-2.5% by weight, calculated as lithium ions, based on the total molar amount of lithium and molecular sieve.
  • the method of the present invention further includes obtaining the molecular sieve as follows:
  • the lithium ion solution is selected from at least one of lithium chloride, lithium sulfate, and lithium nitrate.
  • the exchange is carried out under conditions including the following: temperature is 40-100°C, and liquid-solid ratio is 10-50.
  • the exchange may be performed once or multiple times, for example, 1-3 exchanges.
  • the cobalt ion solution is selected from at least one of cobalt chloride solution, cobalt nitrate solution, cobalt sulfate solution, and cobalt acetate solution.
  • the reduction is carried out in a hydrogen atmosphere at a temperature of 600-750°C for 1-4 hours.
  • the raw material molecular sieve has a chemical composition shown as “xM 2 O ⁇ ySiO 2 ⁇ zAl 2 O 3 ”, where 0.01 ⁇ x/y ⁇ 0.2, 10 ⁇ y/z ⁇ 50, and M is selected from Na, One or two of K.
  • the raw material molecular sieve is Na-type molecular sieve, that is, M is Na.
  • the raw material molecules are selected from at least one of MFI, MWW, GIS, BEC, FAU and MOR, preferably at least one of MFI, MWW and GIS.
  • the molecular sieve in step (1) has a topological structure selected from at least one of MFI, MWW, GIS, BEC, FAU and MOR, preferably at least one selected from MFI, MWW and GIS.
  • a topological structure selected from at least one of MFI, MWW, GIS, BEC, FAU and MOR, preferably at least one selected from MFI, MWW and GIS.
  • the solvent in step (2) can be a conventional material in this field.
  • the solvent in step (2) is selected from deionized water, absolute ethanol, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide and N -At least one of methylpyrrolidone, preferably N-methylpyrrolidone.
  • the adhesive in step (2) can be a conventional material in this field.
  • the binder in step (2) is polyvinyl alcohol, carboxymethyl cellulose, polyvinylidene fluoride, polytetrafluoroethylene, polyvinylpyrrolidone, styrene-butadiene rubber and polyacrylate. At least one of them is preferably polyvinylidene fluoride.
  • the coating in step (3) may be a conventional method in this field.
  • the coating in step (3) is at least one of a casting method, a blade coating method, a spray coating method, and a spin coating method, and is preferably a blade coating method.
  • a third aspect of the present invention provides an application of the composite separator in a lithium-sulfur battery.
  • a fourth aspect of the present invention provides a lithium-sulfur battery, which includes a positive electrode, a negative electrode and the above-mentioned composite separator located between the positive electrode and the negative electrode.
  • the lithium-sulfur battery also contains an electrolyte.
  • the positive electrode, negative electrode and electrolyte solution may be respectively selected from various positive electrodes, negative electrodes and electrolyte solutions used in lithium-sulfur batteries known to those skilled in the art.
  • the composite separator of the present invention contains a molecular sieve containing cobalt and optionally lithium in the composite layer.
  • the pore structure of the molecular sieve can effectively limit the migration and diffusion of Li2Sx through physical barriers and reduce side reactions inside the battery.
  • the molecular sieve of the present invention contains cobalt, and the introduced cobalt can not only improve the conductivity of the positive electrode side of the separator, but also serve as an active site to enhance the conversion reaction kinetics of polysulfides.
  • the molecular sieve further contains lithium, the introduced lithium can provide a large number of sites for the adsorption and transmission of lithium ions during battery cycles, improving the lithium ion transmission performance of the separator. More importantly, when the molecular sieve contains lithium and cobalt, a synergistic effect is achieved in the resulting composite separator, which can greatly improve the rate performance and cycle stability of lithium-sulfur batteries.
  • MFI type molecular sieve, GIS type molecular sieve, MWW type molecular sieve, BEC type molecular sieve purchased from Sigma-Aldrich,
  • Graphene, graphene oxide purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.
  • PVDF, NMP, CMC, DMF, cobalt chloride purchased from Sinopharm Chemical Reagent Co., Ltd.
  • the positive electrode mix the active material sublimated sulfur, the conductive agent Ketjen Black, and the binder polyvinylidene fluoride at a mass ratio of 6:3:1, add N-methylpyrrolidone to form a positive electrode slurry; The material is coated on aluminum foil and dried to obtain a positive electrode. Then assemble the 2025 button battery in an argon glove box with a water and oxygen content lower than 0.1ppm: assemble in the order of positive electrode shell, positive electrode, separator, lithium negative electrode, nickel foam, and negative electrode shell, and add 100 ⁇ L electrolyte.
  • the electrolyte used was 1,3-dioxolane/ethylene glycol dimethyl ether (DOL/DME, volume) containing 1 mol/L lithium bis(trifluoromethylsulfonyl)imide and 0.2 mol/L lithium nitrate. The ratio is 1:1) mixed solution.
  • the rate performance and cycle performance of the lithium-sulfur battery samples prepared as described above were tested through constant current charge and discharge tests.
  • the average discharge specific capacity of 5 cycles at 1C the sum of the discharge specific capacities from the 1st cycle to the 5th cycle/5
  • the lithium-sulfur battery sample was charged and discharged for 2 cycles at 0.1 and 0.2C in the voltage range of 1.7-2.7V, and then continued to be cycled for 100 and 150 cycles at 0.5C. Record the discharge specific capacity after the first cycle and the 100th and 150th cycles at different current densities (i.e., the above-mentioned 0.1C, 0.2C and 0.5C). Calculate the capacity retention rate after 100 or 150 cycles at 0.5C according to the following formula to characterize the cycle performance.
  • Capacity retention rate after 100 cycles discharge specific capacity of the 100th cycle/discharge specific capacity of the 1st cycle * 100%.
  • Capacity retention rate after 150 cycles discharge specific capacity of the 150th cycle/discharge specific capacity of the first cycle * 100%.
  • the prepared composite separator was used to assemble lithium-sulfur battery samples and perform performance tests. See Table 2-1 for specific test results.
  • Figure 1 is a scanning electron microscope picture of the composite separator of Example 2-1. As shown in the figure, the composite layer evenly covers the surface of the PP/PE film, forming a good barrier layer;
  • Figure 2 shows the charge and discharge curves of lithium-sulfur battery samples containing the composite separator of Example 2-1 at different current densities.
  • Example 2-1 except that the MFI type molecular sieve is replaced by the GIS type molecular sieve to prepare a GIS type molecular sieve containing lithium and cobalt with the same composition.
  • LiCl solution liquid-to-solid ratio of 20 were ion-exchanged at 80°C for 2 hours , then centrifuge and wash. Repeat the above ion exchange twice. The obtained sample is dried at 100°C overnight to obtain precursor 2-I.
  • the amount of the GIS type molecular sieve containing lithium and cobalt was adjusted to 0.6g, and the thickness of the composite layer was adjusted to 30 ⁇ m to prepare a composite separator.
  • Example 2-1 use the prepared composite separator to assemble lithium-sulfur battery samples and perform performance tests.
  • the test results are shown in Table 2-1.
  • Example 2-1 except that the MFI type molecular sieve is replaced by the MWW type molecular sieve to prepare a MWW type molecular sieve containing lithium and cobalt with the same composition.
  • 5 g of raw material molecular sieve (MWW type molecular sieve with the composition of Na 2 O ⁇ 20SiO 2 ⁇ Al 2 O 3 ) and 0.5 mol/L LiCl solution (liquid-to-solid ratio of 20) were ion exchanged at 80°C 2 hours, then centrifuged and washed. Repeat the above ion exchange twice. The obtained sample was dried at 100°C overnight to obtain precursor 3-I.
  • the amount of the MWW type molecular sieve containing lithium and cobalt was adjusted to 0.9g, and the thickness of the composite layer was adjusted to 40 ⁇ m to prepare a composite separator.
  • Example 2-1 use the prepared composite separator to assemble lithium-sulfur battery samples and perform performance testing.
  • the test results are shown in Table 2-1.
  • Example 2-1 Repeat Example 2-1, except that the weight of the MFI-type molecular sieve containing lithium and cobalt is adjusted to 1 g.
  • Example 2-1 use the prepared composite separator to assemble lithium-sulfur samples and perform performance testing.
  • the test results are shown in Table 2-1.
  • Example 2-1 Repeat Example 2-1, except that the thickness of the composite layer is adjusted to 50 ⁇ m.
  • Example 2-1 use the prepared composite separator to assemble lithium-sulfur battery samples and perform performance testing.
  • the test results are shown in Table 2-1.
  • Example 2-1 except that the MFI type molecular sieve with a composition of Na 2 O ⁇ 20SiO 2 ⁇ Al 2 O 3 is replaced with an MFI type molecular sieve with a composition of 2Na 2 O ⁇ 5SiO 2 ⁇ Al 2 O 3 , To prepare MFI-type molecular sieves containing lithium and cobalt.
  • Example 2-1 use the prepared composite separator to assemble lithium-sulfur battery samples and perform performance testing.
  • the test results are shown in Table 2-1.
  • Example 2-1 Repeat Example 2-1, except that the MFI molecular sieve containing lithium and cobalt is replaced with the raw material MFI molecular sieve.
  • Example 2-1 use the prepared composite separator to assemble lithium-sulfur battery samples and perform performance tests.
  • the test results are shown in Table 2-1.
  • Example 2-1 Repeat Example 2-1, except that the MFI type molecular sieve is replaced with the 13X type molecular sieve to prepare the 13X type molecular sieve containing lithium and cobalt with the same composition.
  • Example 2-1 use the prepared composite separator to assemble lithium-sulfur battery samples and perform performance testing.
  • the test results are shown in Table 2-1.
  • Example 2-1 Repeat Example 2-1, except that the MFI molecular sieve is replaced with a SAPO-34 molecular sieve to prepare a SAPO-34 molecular sieve containing lithium and cobalt with the same composition.
  • Example 2-1 use the prepared composite separator to assemble lithium-sulfur battery samples and perform performance testing.
  • the test results are shown in Table 2-1.
  • Example 2-1 Repeat Example 2-1, except that Precursor I is used to replace the MFI type molecular sieve containing lithium and cobalt to prepare a composite separator.
  • Example 2-1 use the prepared composite separator to assemble lithium-sulfur battery samples and perform performance testing.
  • the test results are shown in Table 2-1.
  • the prepared composite separator was used to assemble lithium-sulfur battery samples and perform performance tests.
  • the test results are shown in Table 3-1.
  • Example 3-1 except that the MFI type molecular sieve is replaced by the GIS type molecular sieve to prepare a cobalt-containing GIS type molecular sieve of the same composition.
  • 2 g of raw material molecular sieve (GIS type molecular sieve with a composition of Na 2 O ⁇ 20SiO 2 ⁇ Al 2 O 3 ) was immersed in 18 mL of cobalt chloride solution with a concentration of 0.1 mol/L, and dried under air conditions at 80°C. After 8 hours, it was treated in a hydrogen atmosphere at 700°C for 2 hours to obtain a cobalt-containing GIS molecular sieve.
  • the amount of the cobalt-containing GIS type molecular sieve was adjusted to 0.6g, and the thickness of the composite layer was adjusted to 30 ⁇ m to prepare a composite separator.
  • Example 3-1 use the prepared composite separator to assemble lithium-sulfur battery samples and perform performance testing.
  • the test results are shown in Table 3-1.
  • Example 2-1 Repeat Example 2-1, except that the MFI molecular sieve is replaced by the MWW molecular sieve to prepare a cobalt-containing MWW molecular sieve of the same composition.
  • 2 g of raw material molecular sieve MWW type molecular sieve with a composition of Na 2 O ⁇ 20SiO 2 ⁇ Al 2 O 3
  • cobalt chloride solution with a concentration of 0.1 mol/L
  • the amount of the cobalt-containing MWW molecular sieve was adjusted to 0.9g, and the thickness of the composite layer was adjusted to 40 ⁇ m to prepare a composite membrane.
  • Example 3-1 use the prepared composite separator to assemble lithium-sulfur battery samples and perform performance testing.
  • the test results are shown in Table 3-1.
  • Example 3-1 Repeat Example 3-1, except that the weight of the cobalt-containing MFI molecular sieve is adjusted to 1 g.
  • Example 3-1 use the prepared composite separator to assemble lithium-sulfur samples and perform performance testing.
  • the test results are shown in Table 3-1.
  • Example 3-1 Repeat Example 3-1, except that the thickness of the composite layer is adjusted to 50 ⁇ m.
  • Example 3-1 use the prepared composite separator to assemble lithium-sulfur battery samples and perform performance testing.
  • the test results are shown in Table 3-1.
  • Example 3-1 except that the MFI type molecular sieve with a composition of Na 2 O ⁇ 20SiO 2 ⁇ Al 2 O 3 is replaced with an MFI type molecular sieve with a composition of 2Na 2 O ⁇ 5SiO 2 ⁇ Al 2 O 3 , To prepare cobalt-containing MFI molecular sieves.
  • Example 3-1 use the prepared composite separator to assemble lithium-sulfur battery samples and perform performance testing.
  • the test results are shown in Table 3-1.

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Abstract

本发明涉及一种复合隔膜及其制备方法和应用，并涉及含有所述复合隔膜的锂硫电池。所述复合隔膜包括聚合物基体膜以及分布在聚合物基体膜的表面的复合层，所述复合层包含分子筛和导电碳材料，其中所述分子筛含有钴和任选的锂。与现有隔膜相比，本发明复合隔膜表面具有包含含有钴和任选的锂的分子筛的复合层，能够大幅度提高电池的倍率性能和循环稳定性。

Description

复合隔膜及其制备方法和含有其的锂硫电池 技术领域
本发明涉及电池隔膜领域，具体涉及一种复合隔膜及其制备方法和含有其的锂硫电池。
背景技术
随着科技的快速发展，锂离子电池因其正极材料较低的理论比容量，难以满足新能源电动汽车以及大容量储能系统对更高能量密度电池的需求。锂硫电池具有较高的理论比容量(1675mAh/g)和理论能量密度(2600Wh/kg)，是锂离子电池有前景的替代品，已成为下一代高比能二次电池的研究重点。此外，其正极材料活性材料硫还具备自然资源丰富、价格低廉和环境友好等优势。
但是，现阶段锂硫电池的实用化还面临诸多挑战，其中电池内部的副反应“穿梭效应”，是限制其应用的最大阻碍。具体而言，穿梭效应即：锂硫电池在充放电过程会产生一系列含硫中间产物，其中长链多硫化物(Li 2S x，2＜x≤8)易溶于电解液，并在浓度梯度和电场的作用下，穿过隔膜与锂负极发生化学副反应，造成活性物质损失和电池内阻增加，从而导致电池容量降低和循环性能下降。此外，锂硫电池由于电化学反应过程涉及多步固液转化，并且硫以及放电终产物硫化锂电子导电性较差，因此多硫化物转化反应动力学缓慢，电池倍率性能较差。
目前，现有技术已有利用分子筛对常规隔膜进行修饰，以抑制锂硫电池的穿梭效应，比如CN107546356A和CN103490027A。它们利用ZSM-5、SAPO-34、3A、13X等分子筛的物理阻隔作用，在一定程度上限制了Li 2S x在电解液中的迁移扩散，从而改善电池性能。
为了使(锂硫)电池能够满足新能源电动汽车以及大容量储能系统对更高能量密度电池的需求，目前仍然需要开发实现性能进一步改善的电池隔膜。
发明内容
本发明的目的是为了克服现有技术存在的电池倍率性能较差、电 池容量低和循环性能差的问题。本发明的发明人发现，通过将含有钴和任选的锂的分子筛用于锂硫电池隔膜，可以进一步改善电池的性能，从而满足现有技术的上述需求。因此，提供一种复合隔膜，其包含含有钴和任选的锂的分子筛的复合层。本发明的复合隔膜能够改善电池的倍率性能和循环稳定性。本发明还提供了上述复合隔膜的制备方法和含有所述复合隔膜的锂硫电池。
本发明第一方面提供一种复合隔膜，其包括聚合物基体膜以及分布在聚合物基体膜的表面的复合层，其中所述复合层包含分子筛和导电碳材料，其中所述分子筛含有钴。
本发明第二方面提供一种所述复合隔膜的制备方法，该方法包括：
(1)混合分子筛与导电碳材料，得到混合物，其中所述分子筛含有钴；
(2)将所述混合物与粘结剂分散在溶剂中，得到涂布浆料；
(3)将所述涂布浆料涂覆在聚合物基体膜表面，然后去除溶剂，得到复合隔膜。
本发明三方面提供一种所述复合隔膜在锂硫电池中的应用。
本发明四方面提供一种锂硫电池，其包括正极，负极和位于正极负极之间的上述复合隔膜。
本发明可以体现为以下各项：
1、一种分子筛改性隔膜，其特征在于，所述隔膜包括聚合物基体膜以及分布在聚合物基体膜的表面的钴掺杂分子筛/导电碳材料复合层。
2、第1项所述的隔膜，其中，
所述钴掺杂分子筛/导电碳材料复合层的厚度为5-50μm，优选为10-40μm；和/或
所述钴掺杂分子筛/导电碳材料复合层中，导电碳材料与钴掺杂分子筛的质量比为1∶(1-9)，优选为1∶(2-9)。
3、第1或2项所述的隔膜，其中，
所述钴掺杂分子筛具有如式“aCo·bM 2O·ySiO 2·zAl 2O 3”所示的化学组成，优选所述钴掺杂分子筛选自MFI、MWW、GIS、BEC、FAU和MOR中的至少一种，更优选所述钴掺杂分子筛为MFI、MWW和GIS中的至少一种；
其中，
0.02≤a/y≤0.2，0.01≤b/y≤0.2，10≤y/z≤50；M为IA族碱金属元素，优选自Na、K、Li中的一种或几种；
优选所述钴掺杂分子筛为钴掺杂锂化分子筛，所述钴掺杂锂化分子筛具有如式“aCo·bLi 2O·ySiO 2·zAl 2O 3”所示的化学组成，其中，0.02≤a/y≤0.2，0.01≤b/y≤0.2，10≤y/z≤50。
4、第1-3项中任意一项所述的隔膜，其中，
所述聚合物基体膜的材料为聚乙烯、聚丙烯、聚酰亚胺、聚丙烯腈、聚对苯二甲酸乙二醇酯、聚四氟乙烯和聚偏氟乙烯中的至少一种，优选为聚乙烯和/或聚丙烯；和/或
所述导电碳材料为石墨烯、氧化石墨烯、还原氧化石墨烯、碳纳米管、碳纳米纤维、乙炔黑、Super P和科琴黑中的至少一种，优选为石墨烯、氧化石墨烯和还原氧化石墨烯中的至少一种。
5、第1-4项中任一项所述分子筛改性隔膜的制备方法，其特征在于，该方法包括：
(1)将钴掺杂分子筛与导电碳材料研磨混合，得到钴掺杂分子筛和导电碳材料混合物；
(2)将所述钴掺杂分子筛和导电碳材料混合物与粘结剂分散在溶剂中，得到涂布浆料；
(3)将所述涂布浆料涂覆在聚合物基体膜表面，然后去除溶剂，得到分子筛改性隔膜。
6、第5项所述的制备方法，其中，
钴掺杂分子筛的制备方法包括：将钴离子溶液加入到Na型分子筛经过干燥并还原，得到钴掺杂分子筛；
优选所述钴掺杂分子筛为钴掺杂锂化分子筛，制备方法包括：
S1、将Na型分子筛与锂离子溶液交换、洗涤、干燥后得到前驱体I；
S2、将钴离子溶液加入到前驱体I中经过干燥并还原，得到钴掺杂锂化分子筛；
其中，优选地，
所述S1中的锂离子溶液为氯化锂溶液、硫酸锂溶液、硝酸锂中溶液的至少一种；
所述S1中的交换的条件包括：温度为40-100℃，液固比为10-50；
所述Na型分子筛具有“bNa 2O·ySiO 2·zAl 2O 3”所示的化学组成，其中，0.01≤b/y≤0.2，10≤y/z≤50；优选所述Na型分子筛的拓扑结构选自MFI、MWW、GIS、BEC、FAU和MOR中的至少一种；
所述钴离子溶液为氯化钴溶液、硝酸钴溶液、硫酸钴溶液、乙酸钴溶液中的至少一种；
所述还原的条件包括：还原的气氛为氢气气氛，还原温度为600-750℃，还原时间为1-4h。
7、第5或6项所述的制备方法，其中，步骤(2)所述溶剂选自去离子水、无水乙醇、N，N-二甲基乙酰胺、N，N-二甲基甲酰胺、二甲基亚砜和N-甲基吡咯烷酮中的至少一种，优选为N-甲基吡咯烷酮。
8、第5-7项中任意一项所述的制备方法，其中，步骤(2)所述粘结剂为聚乙烯醇、羧甲基纤维素、聚偏氟乙烯、聚四氟乙烯、聚乙烯吡咯烷酮、丁苯橡胶和聚丙烯酸酯中的至少一种，优选为聚偏氟乙烯。
9、第5-8项中任意一项所述的制备方法，其中，
步骤(3)所述涂覆方法为流延法、刮涂法、喷涂法、旋涂法中的至少一种，优选为刮涂法。
10、第1-4项中任意一项所述分子筛改性隔膜在锂硫电池中的应用。
本发明还可以体现为以下各项：
1、一种锂化分子筛改性隔膜，其特征在于，所述隔膜包括锂化分子筛/导电碳材料复合层和聚合物基体膜；所述锂化分子筛/导电碳材料复合层分布在聚合物基体膜的表面。
2、第1项所述的锂化分子筛改性隔膜，其中，所述锂化分子筛包括锂化MFI型分子筛、锂化MWW型分子筛、锂化GIS型分子筛、锂化BEC型分子筛、锂化FAU型分子筛和锂化MOR型分子筛中的至少一种，优选为锂化MFI型分子筛、锂化MWW型分子筛和锂化GIS型分子筛的至少一种。
3、第1或2项所述的锂化分子筛改性隔膜，其中，所述聚合物基体膜的材料为聚乙烯、聚丙烯、聚酰亚胺、聚丙烯腈、聚对苯二甲酸乙二醇酯、聚四氟乙烯和聚偏氟乙烯中的至少一种，优选为聚乙烯和/或聚丙烯。
4、第1-3项中任意一项所述的锂化分子筛改性隔膜，其中，所述锂化分子筛/导电碳材料复合层的厚度为2-40μm，优选为5-25μm。
5、第1-4项中任意一项所述的锂化分子筛改性隔膜，其中，
所述锂化分子筛/导电碳材料复合层中，导电碳材料与锂化分子筛的质量比为1∶(1-9)，优选为1∶(2-9)；和/或
所述锂化分子筛具有如式“xLi 2O·ySiO 2·zAl 2O 3”所示的化学组成，其中，0.01≤x/y≤0.2，10≤y/z≤50。
6、第1-5项中任意一项所述的锂化分子筛改性隔膜，其中，所述导电碳材料为石墨烯、氧化石墨烯、还原氧化石墨烯、碳纳米管、碳纳米纤维、乙炔黑、Super P、科琴黑中的至少一种，优选为石墨烯、氧化石墨烯、还原氧化石墨烯中的至少一种。
7、第1-6项中任意一项所述锂化分子筛改性隔膜的制备方法，其特征在于，该方法包括：
(1)将锂化分子筛与导电碳材料研磨混合，得到锂化分子筛和导电碳材料混合物；
(2)将所述锂化分子筛和导电碳材料混合物与粘结剂分散在溶剂中，得到涂布浆料；
(3)将所述涂布浆料涂覆在聚合物基体膜表面，然后去除溶剂，得到锂化分子筛改性隔膜。
8、第7项所述的制备方法，其中，
步骤(2)中，
所述溶剂为去离子水、无水乙醇、N，N-二甲基乙酰胺、N，N-二甲基甲酰胺、二甲基亚砜、N-甲基吡咯烷酮中的至少一种，优选为N-甲基吡咯烷酮；和/或，
所述粘结剂为聚乙烯醇、聚四氟乙烯、聚乙烯吡咯烷酮、羧甲基纤维素、丁苯橡胶、聚偏氟乙烯、聚丙烯酸酯中的至少一种，优选为聚偏氟乙烯；
和/或，
步骤(3)所述涂覆的方法为流延法、刮涂法、喷涂法、旋涂法中的至少一种，优选为刮涂法；
和/或
所述锂化分子筛的制备方法包括：将Na型分子筛经过与锂离子溶 液交换、洗涤、干燥后得到Li型分子筛；
其中，
所述Na型分子筛具有“xNa 2O·ySiO 2·zAl 2O 3”所示的化学组成，其中，0.01≤x/y≤0.2，10≤y/z≤50；优选所述Na型分子筛选自MFI分子筛、MWW分子筛、GIS分子筛、BEC分子筛、FAU分子筛和MOR分子筛中的至少一种；
所述锂离子溶液选自氯化锂溶液、硫酸锂溶液、硝酸锂溶液中的至少一种；
所述交换的条件包括：温度为40-100℃，液固比为10-50。
9、第1-8项中任意一项所述锂化分子筛改性隔膜在锂硫电池中的应用。
10、一种锂硫电池，其特征在于，所述锂硫电池包括：正极壳、正极片、隔膜、锂片、泡沫镍、负极壳，所述隔膜为第1-6项中任意一项所述的锂化分子筛改性隔膜。
本发明具有如下优势：
本发明复合隔膜的制备工艺简单，对电池能量密度的影响较小；
本发明的复合隔膜在复合层中包含含有钴和任选的锂的分子筛。在应用于锂硫电池中时，分子筛的孔道构造可通过物理阻隔有效限制Li 2S x的迁移扩散，减少电池内部的副反应。本发明分子筛含有钴，引入的钴既可以改善隔膜正极侧的导电性，还可以作为活性位点增强多硫化物的转化反应动力学。在分子筛进一步含有锂的情况下，引入的锂可以在电池循环中为锂离子的吸附和传输提供大量位点，改善隔膜的锂离子传输性能。更重要的是，在分子筛含有锂和钴时，在所得到的复合隔膜中实现协同效果，可大幅度提高锂硫电池的倍率性能和循环稳定性。
附图说明
图1为实施例2-1中获得的复合隔膜的扫描电镜图片；
图2为实施例2-1中获得的锂硫电池样品在不同电流密度下的充放电曲线。
具体实施方式
在本文中所披露的范围的端点和任何值都不限于该精确的范围或值，这些范围或值应当理解为包含接近这些范围或值的值。对于数值范围来说，各个范围的端点值之间、各个范围的端点值和单独的点值之间，以及单独的点值之间可以彼此组合而得到一个或多个新的数值范围，这些数值范围应被视为在本文中具体公开。除了在实施例外，在本文中，参数的所有数值都应理解为在所有情况下均由术语“约”修饰，无论“约”是否实际上出现在该数值之前。
本发明提供一种复合隔膜，其包括聚合物基体膜以及分布在聚合物基体膜的表面的复合层，其中所述复合层包含分子筛和导电碳材料，其中所述分子筛含有钴。在一个实施方式中，钴在分子筛中的量为1-30重量％，优选1-15重量％，更优选2-7重量％，以单质钴计，基于钴和分子筛的总重量。
在一种实施方式中，所述分子筛进一步含有锂，优选锂在分子筛中的量为0.1-5重量％，优选0.2-3重量％，更优选0.5-2.5重量％，以锂离子计，基于锂和分子筛的总重量。
在一种实施方式中，分子筛具有选自MFI、MWW、GIS、BEC、FAU和MOR中的至少一种的拓扑结构，优选具有选自MFI、MWW和GIS中的至少一种的拓扑结构。
本发明对所述复合层的厚度没有限制。在一种实施方式中，所述复合层的厚度为5-50μm，优选为10-40μm。
本发明对所述复合层中导电碳材料与分子筛的质量比没有限制。根据一种实施方式，所述复合层中，导电碳材料与分子筛的质量比为1∶(1-9)，优选为1∶(2-9)，例如可以是1∶1、1∶2、1∶4、1∶6、1∶8、1∶9。
所述聚合物基体膜的材料可以是本领域的常规材料。根据一种实施方式，所述聚合物基体膜的材料为聚乙烯、聚丙烯、聚酰亚胺、聚丙烯腈、聚对苯二甲酸乙二醇酯、聚四氟乙烯和聚偏氟乙烯中的至少一种，优选为聚乙烯和/或聚丙烯。
所述导电碳材料可以是本领域的常规材料。根据一种实施方式，所述导电碳材料为石墨烯、氧化石墨烯、还原氧化石墨烯、碳纳米管、碳纳米纤维、乙炔黑、Super P和科琴黑中的至少一种，优选为石墨烯、氧化石墨烯和还原氧化石墨烯中的至少一种。
本发明第二方面提供一种复合隔膜的制备方法，该方法包括：
(1)将分子筛与导电碳材料混合，得到混合物，其中所述分子筛含有钴；
(2)将所述混合物与粘结剂分散在溶剂中，得到涂布浆料；
(3)将所述涂布浆料涂覆在聚合物基体膜表面，然后去除溶剂，得到复合隔膜。
在一个实施方式中，钴在分子筛中的量为1-30重量％，优选1-15重量％，更优选2-7重量％，以单质钴计，基于钴和分子筛的总重量。在一种实施方式中，所述方法还包括如下获得所述分子筛：将钴离子溶液加入到原料分子筛中、然后进行干燥和还原，得到含有钴的分子筛。
在一种实施方式中，所述分子筛进一步含有锂。优选，锂在分子筛中的量为0.1-5重量％，优选0.2-3重量％，更优选0.5-2.5重量％，以锂离子计，基于锂和分子筛的总摩尔量。在一种实施方式中，本发明方法还包括如下获得所述分子筛：
S1、将原料分子筛与锂离子溶液进行交换，然后进行洗涤和干燥，得到前驱体I；和
S2、将钴离子溶液加入到前驱体I中，然后进行干燥并还原，得到所述用分子筛，其含有钴和锂。
优选地，所述锂离子溶液选自氯化锂、硫酸锂、硝酸锂中的至少一种。
优选地，所述交换在包括以下的条件下进行：温度为40-100℃，液固比为10-50。所述交换可以进行一次或多次，例如进行1-3次交换。
优选地，所述钴离子溶液选自氯化钴溶液、硝酸钴溶液、硫酸钴溶液、乙酸钴溶液中的至少一种。
优选地，所述还原在氢气气氛下，在600-750℃的温度下，进行1-4h。
优选地，原料分子筛具有“xM 2O·ySiO 2·zAl 2O 3”所示的化学组成，其中，0.01≤x/y≤0.2，10≤y/z≤50，并且M为选自Na、K中的一种或两种。优选，原料分子筛为Na型分子筛，即所述M为Na。
优选地，原料分子筛选自MFI、MWW、GIS、BEC、FAU和MOR中的至少一种，优选为MFI、MWW和GIS中的至少一种。
在一种实施方式中，步骤(1)中所述分子筛具有选自MFI、MWW、 GIS、BEC、FAU和MOR中的至少一种的拓扑结构，优选具有选自MFI、MWW和GIS中的至少一种的拓扑结构。
所述步骤(2)所述溶剂可以是本领域的常规材料。根据一种实施方式，步骤(2)所述溶剂选自去离子水、无水乙醇、N，N-二甲基乙酰胺、N，N-二甲基甲酰胺、二甲基亚砜和N-甲基吡咯烷酮中的至少一种，优选为N-甲基吡咯烷酮。
步骤(2)所述粘结剂可以是本领域的常规材料。根据本发明一种实施方式，步骤(2)所述粘结剂为聚乙烯醇、羧甲基纤维素、聚偏氟乙烯、聚四氟乙烯、聚乙烯吡咯烷酮、丁苯橡胶和聚丙烯酸酯中的至少一种，优选为聚偏氟乙烯。
步骤(3)所述涂覆可以是本领域的常规方法。根据一种实施方式，步骤(3)所述涂覆为流延法、刮涂法、喷涂法、旋涂法中的至少一种，优选为刮涂法。
本发明第三方面提供一种所述复合隔膜在锂硫电池中的应用。
本发明第四方面提供一种锂硫电池，其包括正极，负极和位于正极负极之间的上述复合隔膜。所述锂硫电池还包含电解液。所述正极、负极和电解液可以分别选自本领域技术人员公知的锂硫电池中所用的各种正极、负极和电解液。
本发明的复合隔膜在复合层中包含含有钴和任选的锂的分子筛。在应用于锂硫电池中时，分子筛的孔道构造可通过物理阻隔有效限制Li2Sx的迁移扩散，减少电池内部的副反应。本发明分子筛含有钴，引入的钴既可以改善隔膜正极侧的导电性，还可以作为活性位点增强多硫化物的转化反应动力学。在分子筛进一步含有锂的情况下，引入的锂可以在电池循环中为锂离子的吸附和传输提供大量位点，改善隔膜的锂离子传输性能。更重要的是，在分子筛含有锂和钴时，在所得到的复合隔膜中实现协同效果，可大幅度提高锂硫电池的倍率性能和循环稳定性。
以下将通过实施例对本发明进行详细描述。
原料列表：
MFI型分子筛、GIS型分子筛、MWW型分子筛、BEC型分子筛：购自Sigma-Aldrich，
石墨烯、氧化石墨烯：购自上海阿拉丁生化科技股份有限公司
PVDF、NMP、CMC、DMF、氯化钴：购自国药集团化学试剂有限公司
测试方法：
锂硫电池样品的组装：
首先制备正极：将活性物质升华硫、导电剂科琴黑、粘结剂聚偏氟乙烯按照质量比为6∶3∶1进行混合，加入N-甲基吡咯烷酮，形成正极浆料；将正极浆料涂覆在铝箔上，并烘干，得到正极。然后在水氧含量低于0.1ppm的氩气手套箱内组装2025扣式电池：按照正极壳、正极、隔膜、锂负极、泡沫镍、负极壳的顺序依次组装，并加入100μL电解液。所用电解液是包含有1mol/L二(三氟甲基磺酰基)亚胺锂和0.2mol/L硝酸锂的1，3-二氧戊环/乙二醇二甲醚(DOL/DME，体积比为1∶1)混合溶液。
通过恒流充放电测试检测如上所述制备的锂硫电池样品的倍率性能和循环性能。
倍率性能测试：
将锂硫电池样品在1.7-2.7V的电压范围，在1C(1C＝1675mA/g)下充放电循环5圈。记录相应充放电循环的放电比容量，计算5圈循环的平均放电比容量：
在1C下的5圈的平均放电比容量＝第1圈循环至第5圈循环的放电比容量之和/5
类似地，在2C和3C下重复充放电循环5圈，测量在2C和3C下的5圈循环的平均放电比容量。
循环性能测试：
将锂硫电池样品在1.7-2.7V的电压范围内，分别在0.1和0.2C下充放电循环2圈，然后继续将锂硫电池样品在0.5C下循环100圈和150圈。记录在不同电流密度(即上述的0.1C、0.2C和0.5C)下的首次循环以及第100圈循环和第150圈循环后的放电比容量。根据以下公式计算在0.5C下循环100圈或150圈后的容量保持率，用来表征循环性能。
循环100圈后的容量保持率＝第100圈循环的放电比容量/第1圈循环的放电比容量*100％。
循环150圈后的容量保持率＝第150圈循环的放电比容量/第1 圈循环的放电比容量*100％。
涉及分子筛含有锂和钴的情况
实施例2-1
复合隔膜的制备：
(1)将5g原料分子筛(组成为Na 2O·20SiO 2·Al 2O 3的MFI型分子筛)与0.5mol/L的LiCl溶液(液固比为20)在80℃下进行离子交换2小时，然后离心洗涤。重复上述离子交换两次。得到的样品在100℃下过夜烘干，得前驱体1-I。
将2g制得的前驱体1-I浸渍于18mL浓度为0.1mol/L的氯化钴溶液中，于80℃空气条件干燥处理8h后，在700℃氢气气氛下处理2h，得到含有锂和钴的MFI型分子筛。
(2)将0.35g含有锂和钴的MFI型分子筛与0.1g石墨烯在研钵中研磨混合，得到混合物；
(3)将所述混合物与0.05g聚偏氟乙烯分散在N-甲基吡咯烷酮中，进行搅拌，混合均匀，得到涂布浆料；
(4)将所述涂布浆料利用刮涂法均匀涂覆在聚乙烯/聚丙烯基体膜一侧表面，然后烘干去除溶剂，得到聚合物基体膜的一侧表面均匀分布有复合层的复合隔膜，其中复合层的厚度为15μm。
复合隔膜的性能测试：
根据上文有关测试方法的描述，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。具体测试结果见表2-1。
图1为实施例2-1的复合隔膜的扫描电镜图片。如图所示，复合层均匀覆盖在PP/PE膜表面，形成良好的阻隔层；
图2为含有实施例2-1的复合隔膜的锂硫电池样品在不同电流密度下的充放电曲线。
实施例2-2
重复实施例2-1，不同之处在于：将MFI型分子筛替换为GIS型分子筛来制备同组成的含有锂和钴的GIS型分子筛。具体地说，将5g原料分子筛(组成为Na 2O·20SiO 2·Al 2O 3的GIS型分子筛)与0.5mol/L的LiCl溶液(液固比为20在80℃下进行离子交换2小时，然后离心洗 涤。重复上述离子交换两次。得到的样品在100℃下过夜烘干，得前驱体2-I。将2g制得的前驱体2-I浸渍于18mL浓度为0.1mol/L的氯化钴溶液中，于80℃空气条件干燥处理8h后，在700℃氢气气氛下处理2h，得到所述含有锂和钴的GIS型分子筛。
另外，将所述含有锂和钴的GIS型分子筛的用量调整为0.6g，并将复合层的厚度调整为30μm，来制备复合隔膜。
重复实施例2-1，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。测试结果见表2-1。
实施例2-3
重复实施例2-1，不同之处在于：将MFI型分子筛替换为MWW型分子筛来制备同组成的含有锂和钴的MWW型分子筛。具体地说，将5g原料分子筛(组成为Na 2O·20SiO 2·Al 2O 3的MWW型分子筛)与0.5mol/L的LiCl溶液(液固比为20)在80℃下进行离子交换2小时，然后离心洗涤。重复上述离子交换两次。得到的样品在100℃下过夜烘干，得前驱体3-I。将2g制得的前驱体3-I浸渍于18mL浓度为0.1mol/L的氯化钴溶液中，于80℃空气条件干燥处理8h后，在700℃氢气气氛下处理2h，得到所述含有锂和钴的MWW型分子筛。
另外，将所述含有锂和钴的MWW型分子筛的用量调整为0.9g，并将复合层的厚度调整为40μm，来制备复合隔膜。
重复实施例2-1，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。测试结果见表2-1。
实施例2-5
重复实施例2-1，不同之处在于：将所述含有锂和钴的MFI型分子筛的重量调整为1g。
重复实施例2-1，利用制备的复合隔膜组装锂硫样品并进行性能测试。测试结果见表2-1。
实施例2-6
重复实施例2-1，不同之处在于：将复合层的厚度调整为50μm。
重复实施例2-1，利用制备的复合隔膜组装锂硫电池样品并进行性 能测试。测试结果见表2-1。
实施例2-7
重复实施例2-1，不同之处在于：将组成为Na 2O·20SiO 2·Al 2O 3的MFI型分子筛替换为组成为2Na 2O·5SiO 2·Al 2O 3的MFI型分子筛，来制备含有锂和钴的MFI型分子筛。
重复实施例2-1，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。测试结果见表2-1。
对比例2-1
重复实施例2-1相比，不同之处在于：将含有锂和钴的MFI型分子筛替换为原料MFI型分子筛。
重复实施例2-1，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。测试结果见表2-1。
对比例2-2
重复实施例2-1相比，不同之处在于：将MFI型分子筛替换为13X型分子筛来制备同组成的含有锂和钴的13X型分子筛。
重复实施例2-1，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。测试结果见表2-1。
对比例2-3
重复实施例2-1相比，不同之处在于：将MFI型分子筛替换为SAPO-34型分子筛来制备同组成的含有锂和钴的SAPO-34型分子筛。
重复实施例2-1，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。测试结果见表2-1。
对比例2-4
重复实施例2-1相比，不同之处在于：用前驱体I替代所述含有锂和钴的MFI型分子筛来制备复合隔膜。
重复实施例2-1，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。测试结果见表2-1。
表2-1所测锂硫电池样品的性能测试结果
Figure PCTCN2022121937-appb-000001
涉及分子筛含有钴的情况
实施例3-1
(1)将2g原料分子筛(组成为Na 2O·20SiO 2·Al 2O 3的MFI分子筛)浸渍于18mL浓度为0.1mol/L的氯化钴溶液中，于80℃空气条件干燥处理8h后，在700℃氢气气氛下处理2h，得到含有钴的MFI型分子筛。
(2)将0.35g含有钴的MFI型分子筛与0.1g石墨烯在研钵中研磨混合，得到混合物；
(3)将所述混合物与0.05g聚偏氟乙烯分散在N-甲基吡咯烷酮中，进行搅拌，混合均匀，得到涂布浆料；
(4)将所述涂布浆料利用刮涂法均匀涂覆在聚乙烯/聚丙烯基体膜一侧表面，然后烘干去除溶剂，得到聚合物基体膜的一侧表面均匀分布有复合层的复合隔膜，其中复合层的厚度为15μm。
根据上文有关测试方法的描述，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。测试结果见表3-1。
实施例3-2
重复实施例3-1，不同之处在于：将MFI型分子筛替换为GIS型分子筛来制备同组成的含钴的GIS型分子筛。具体地说，将2g原料分子筛(组成为Na 2O·20SiO 2·Al 2O 3的GIS型分子筛)浸渍于18mL浓度为0.1mol/L的氯化钴溶液中，于80℃空气条件干燥处理8h后，在700℃氢气气氛下处理2h，得到含钴的GIS型分子筛。
另外，将所述含钴的GIS型分子筛的用量调整为0.6g，并将复合层的厚度调整为30μm，来制备复合隔膜。
重复实施例3-1，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。测试结果见表3-1。
实施例3-3
重复实施例2-1，不同之处在于：将MFI型分子筛替换为MWW型分子筛来制备同组成的含钴的MWW型分子筛。具体地说，将2g原料分子筛(组成为Na 2O·20SiO 2·Al 2O 3的MWW型分子筛)浸渍于18mL浓度为0.1mol/L的氯化钴溶液中，于80℃空气条件干燥处理8h后，在700℃氢气气氛下处理2h，得到含钴的MWW型分子筛。
另外，将所述含钴的MWW型分子筛的用量调整为0.9g，并将复合层的厚度调整为40μm，来制备复合隔膜。
重复实施例3-1，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。测试结果见表3-1。
实施例3-4
重复实施例3-1，不同之处在于：将所述含钴的MFI型分子筛的重量调整为1g。
重复实施例3-1，利用制备的复合隔膜组装锂硫样品并进行性能测试。测试结果见表3-1。
实施例3-5
重复实施例3-1，不同之处在于：将复合层的厚度调整为50μm。
重复实施例3-1，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。测试结果见表3-1。
实施例3-6
重复实施例3-1，不同之处在于：将组成为Na 2O·20SiO 2·Al 2O 3的MFI型分子筛替换为组成为2Na 2O·5SiO 2·Al 2O 3的MFI型分子筛，来制备含钴的MFI型分子筛。
重复实施例3-1，利用制备的复合隔膜组装锂硫电池样品并进行性能测试。测试结果见表3-1。
表3-1所测锂硫电池样品的性能测试结果
Figure PCTCN2022121937-appb-000002
以上详细描述了本发明的优选实施方式，但是，本发明并不限于此。在本发明的技术构思范围内，可以对本发明的技术方案进行多种简单变型，包括各个技术特征以任何其它的合适方式进行组合，这些简单变型和组合同样应当视为本发明所公开的内容，均属于本发明的保护范围。

Claims (12)

  1. 一种复合隔膜，其特征在于，所述复合隔膜包括聚合物基体膜以及分布在聚合物基体膜的表面的复合层，所述复合层包含分子筛和导电碳材料，其中所述分子筛含有钴。
  2. 根据权利要求1所述的复合隔膜，其中，
    所述复合层的厚度为5-50μm，优选为10-40μm；和/或
    所述复合层中，导电碳材料与分子筛的质量比为1∶(1-9)，优选为1∶(2-9)。
  3. 根据权利要求1或2所述的复合隔膜，其中，所述分子筛进一步含有锂；
    优选，锂在分子筛中的量为0.1-5重量％，优选0.2-3重量％，更优选0.5-2.5重量％，以锂离子计；
    优选，钴在分子筛中的量为1-30重量％，优选1-15重量％，更优选2-7重量％，以单质钴计。
  4. 根据权利要求3所述的复合隔膜，其中所述分子筛具有选自MFI、MWW、GIS、BEC、FAU和MOR中的至少一种的拓扑结构，优选具有选自MFI、MWW和GIS中的至少一种的拓扑结构。
  5. 根据权利要求1-4任意一项所述的复合隔膜，其中，
    所述聚合物基体膜的材料为聚乙烯、聚丙烯、聚酰亚胺、聚丙烯腈、聚对苯二甲酸乙二醇酯、聚四氟乙烯和聚偏氟乙烯中的至少一种，优选为聚乙烯和/或聚丙烯；和/或
    所述导电碳材料为石墨烯、氧化石墨烯、还原氧化石墨烯、碳纳米管、碳纳米纤维、乙炔黑、Super P和科琴黑中的至少一种，优选为石墨烯、氧化石墨烯和还原氧化石墨烯中的至少一种。
  6. 权利要求1-5任一项所述复合隔膜的制备方法，其特征在于，该方法包括：
    (1)将分子筛与导电碳材料混合，得到混合物，其中所述分子筛含有钴；
    (2)将所述混合物与粘结剂分散在溶剂中，得到涂布浆料；
    (3)将所述涂布浆料涂覆在聚合物基体膜表面，然后去除溶剂，得到复合隔膜。
  7. 根据权利要求6所述的制备方法，其中所述制备方法还包括获得所述分子筛，其包括：将钴离子溶液与原料分子筛混合、然后进行干燥和还原，得到含有钴的分子筛。
  8. 根据权利要求6所述的制备方法，所述分子筛进一步含有锂，并且所述制备方法还包括如下获得所述分子筛：
    S1、将原料分子筛与锂离子溶液进行交换，然后进行洗涤和干燥，得到前驱体I；和
    S2、将钴离子溶液与所述前驱体I混合，然后进行干燥并还原，得到所述分子筛，其含有钴和锂。
  9. 根据权利要求7或8所述的制备方法，其中，
    所述锂离子溶液选自氯化锂、硫酸锂、硝酸锂中的至少一种；和/或
    所述交换在包括以下的条件下进行：温度为40-100℃，液固比为10-50；优选所述交换进行1-3次；和/或
    所述钴离子溶液选自氯化钴溶液、硝酸钴溶液、硫酸钴溶液、乙酸钴溶液中的至少一种；和/或
    所述还原在氢气气氛下，在600-750℃的温度下，进行1-4h；和/或
    原料分子筛具有“xM 2O·ySiO 2·zAl 2O 3”所示的化学组成，其中，0.01≤x/y≤0.2，10≤y/z≤50，并且M为选自Na、K中的一种或两种；优选，M为Na；和/或
    原料分子筛选自MFI、MWW、GIS、BEC、FAU和MOR中的至少一种，优选为MFI、MWW和GIS中的至少一种。
  10. 根据权利要求7或8所述的制备方法，其中，所述分子筛具有选自MFI、MWW、GIS、BEC、FAU和MOR中的至少一种的拓扑结构，更优选具有选自MFI、MWW和GIS中的至少一种的拓扑结构；
    优选，锂在分子筛中的量为0.1-5重量％，优选0.2-3重量％，更优选0.5-2.5重量％，以锂离子计；
    优选，钴在分子筛中的量为1-30重量％，优选1-15摩尔％，更优选2-7重量％，以单质钴计。
  11. 根据权利要求6-9中任意一项所述的制备方法，其中，
    步骤(2)所述溶剂选自去离子水、无水乙醇、N，N-二甲基乙酰胺、 N，N-二甲基甲酰胺、二甲基亚砜和N-甲基吡咯烷酮中的至少一种，优选为N-甲基吡咯烷酮；和/或
    步骤(2)所述粘结剂为聚乙烯醇、羧甲基纤维素、聚偏氟乙烯、聚四氟乙烯、聚乙烯吡咯烷酮、丁苯橡胶和聚丙烯酸酯中的至少一种，优选为聚偏氟乙烯；和/或
    步骤(3)所述涂覆为流延法、刮涂法、喷涂法、旋涂法中的至少一种，优选为刮涂法。
  12. 一种锂硫电池，其特征在于，包括正极，负极和位于正极负极之间的权利要求1-5任意一项所述的复合隔膜。
PCT/CN2022/121937 2022-06-28 2022-09-28 复合隔膜及其制备方法和含有其的锂硫电池 WO2024000873A1 (zh)

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CN102709521A (zh) * 2012-06-12 2012-10-03 宁德新能源科技有限公司 一种锂离子电池及其正极
CN107681091A (zh) * 2017-09-12 2018-02-09 北京理工大学 一种锂硫电池功能化复合隔膜及其制备方法
US20180159171A1 (en) * 2015-06-18 2018-06-07 University Of Southern California Lithium-ion mixed conductor membrane improves the performance of lithium-sulfur battery and other energy storage devices
CN110391386A (zh) * 2019-08-01 2019-10-29 青岛上惠新材料科技有限公司 一种复合隔膜及其制备方法和用途
CN112054153A (zh) * 2020-10-20 2020-12-08 广州市豪越新能源设备有限公司 一种锂硫电池用改性隔膜及其制备方法
CN113270688A (zh) * 2021-05-19 2021-08-17 江南大学 一种环糊精/石墨碳改性锂硫电池隔膜及其制备方法和应用

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CN102709521A (zh) * 2012-06-12 2012-10-03 宁德新能源科技有限公司 一种锂离子电池及其正极
US20180159171A1 (en) * 2015-06-18 2018-06-07 University Of Southern California Lithium-ion mixed conductor membrane improves the performance of lithium-sulfur battery and other energy storage devices
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