Lithium-sulfur battery catalyst performance test system

Abstract

The utility model provides a lithium-sulfur battery catalyst performance test system, and relates to the technical field of lithium-sulfur batteries. The lithium-sulfur battery catalyst performance testing system comprises a to-be-tested catalyst layer and an electrochemical testing device, the electrochemical testing device comprises a positive electrode, a negative electrode, a diaphragm and an electrolysis chamber, electrolyte is arranged in the electrolysis chamber, and polysulfide is contained in the electrolyte; the positive electrode and the negative electrode are arranged on two opposite sides of the electrolysis chamber; the diaphragm is arranged in the electrolysis chamber and between the positive electrode and the negative electrode; wherein the positive electrode comprises a positive electrode current collector layer; the negative electrode comprises a negative electrode current collector layer. The to-be-tested catalyst layer is arranged on the surface, facing the positive current collector layer, of the negative current collector layer. According to the performance test system for the lithium-sulfur battery catalyst, by designing an asymmetric single-side catalytic structure, the oxidation and reduction capability of the lithium-sulfur battery catalyst on polysulfide can be independently and efficiently evaluated.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-sulfur batteries, and in particular to a lithium-sulfur battery catalyst performance testing system. Background Art

[0002] Lithium-sulfur batteries use sulfur as the positive electrode and metallic lithium as the negative electrode. They have high theoretical mass energy density (2600Wh / kg) and volume energy density (2200Wh / L). In addition, the electrode materials are abundant, cheap, and environmentally friendly. However, polysulfides (Li2S x , 2<x≤8) has a serious "shuttle effect", resulting in rapid capacity decay and poor cycling stability of lithium-sulfur batteries, which has greatly hindered the further commercial development of lithium-sulfur batteries. In recent years, a variety of catalysts have been applied to lithium-sulfur batteries to promote the conversion of polysulfides, reduce shuttle effects, and thus improve the battery capacity and cycling stability.

[0003] At present, the methods for studying the effect of catalysts on polysulfide conversion in lithium-sulfur batteries are mainly based on the following two types of technologies: (1) Conventional electrochemical test device: using a standard three-electrode system (working electrode, counter electrode, reference electrode), the catalyst is placed on the working electrode, and the kinetic effect of the catalyst on polysulfide conversion is indirectly inferred by testing methods such as cyclic voltammetry (CV) and constant current charge and discharge. However, in this scheme, due to the uncontrollable diffusion path of sulfur species and the inability to simulate the synergistic effect of the dynamic migration of sulfur cathode and polysulfide in real batteries, the regulation mechanism of the catalyst on multi-step reactions is difficult to analyze. (2) Symmetrical cell: the same catalyst is coated on two identical symmetrical electrodes, and an electrolyte containing polysulfide is injected for constant current charge and discharge or impedance testing. However, in this scheme, the dissolution-deposition behavior of sulfur occurs symmetrically on both sides, and it is impossible to distinguish the differential contributions of the catalyst in the two stages of sulfur reduction (e.g., S8→Li2S6) and deep conversion of polysulfide (e.g., Li2S6→Li2S2), resulting in the averaging of kinetic parameters (such as activation energy and overpotential). Therefore, it is necessary to propose a new lithium-sulfur battery catalyst performance testing system to better evaluate the catalyst performance. Utility Model Content

[0004] The present application is made in view of the above-mentioned problems, and its purpose is to provide a lithium-sulfur battery catalyst performance testing system for better evaluating the performance of lithium-sulfur battery catalysts, especially independently analyzing the oxidation and reduction ability of the catalyst on polysulfides.

[0005] In a first aspect, embodiments of the present application provide a lithium-sulfur battery catalyst performance testing system, comprising a catalyst layer to be tested and an electrochemical testing apparatus, the electrochemical testing apparatus comprising a positive electrode, a negative electrode, a diaphragm, and an electrolysis chamber, wherein an electrolyte containing polysulfides is provided in the electrolysis chamber; the positive electrode and the negative electrode are disposed on opposite sides of the electrolysis chamber, and the diaphragm is disposed within the electrolysis chamber and positioned between the positive and negative electrodes. The positive electrode comprises a positive current collector layer, the negative electrode comprises a negative current collector layer, and the catalyst layer to be tested is disposed on the surface of the negative current collector layer facing the positive current collector layer.

[0006] In the above technical solution, the positive electrode is designed as a blank electrode (i.e., it only includes the positive electrode current collector layer), and the catalyst layer to be tested is set on the negative electrode side to form an asymmetric single-sided catalytic structure, so that the oxidation and reduction ability of the catalyst to be tested on polysulfides can be independently tested and evaluated.

[0007] In one possible implementation, the diaphragm separates the electrolysis chamber into a positive electrode chamber and a negative electrode chamber. The positive electrode, the diaphragm and part of the inner wall of the electrolysis chamber form the positive electrode chamber, and the negative electrode, the diaphragm and another part of the inner wall of the electrolysis chamber form the negative electrode chamber.

[0008] In the above technical solution, by providing a diaphragm to form physical isolation, a positive electrode chamber and a negative electrode chamber are formed, which can avoid interference of the counter-electrode side reaction (such as electrolyte decomposition) on the test signal and improve the test accuracy.

[0009] In a possible implementation, the thickness of the catalyst layer to be tested is 10 μm to 15 μm.

[0010] In the above technical solution, by controlling the thickness of the catalyst layer to be tested within a suitable range and the corresponding loading amount of the catalyst to be tested within a suitable range, sufficient active sites can be provided for the electrochemical reaction, and the moderate thickness can effectively adsorb and catalyze polysulfides, and the polarization internal resistance is small, which can enable the electrochemical reaction to proceed efficiently.

[0011] In a possible implementation, the catalyst layer to be tested includes a catalyst to be tested and a binder.

[0012] In the above technical solution, by mixing the catalyst to be tested and the binder to form the catalyst layer to be tested, the catalyst can be evenly distributed, providing more evenly distributed active sites for the battery reaction and firmly bonding with the current collector.

[0013] In one possible implementation, the positive electrode current collector layer and the negative electrode current collector layer are each independently selected from carbon paper or aluminum foil. Both carbon paper and aluminum foil have good chemical stability and corrosion resistance.

[0014] In one possible implementation, the thickness of the positive and negative current collector layers is independently 10 μm to 20 μm. The thickness of the positive and negative current collector layers within the appropriate range provides suitable surface area and mechanical support, enabling a stable structure during battery preparation and use. This allows the positive and negative current collector layers to withstand volume changes during charge and discharge, providing reliable support for the electrodes and ensuring their integrity and stability, thereby improving the battery's cycle life and safety.

[0015] In a possible implementation, the positive electrode and the negative electrode are each independently circular or square in shape.

[0016] In the above technical solution, the circular or square electrode sheet is convenient for processing by stamping or cutting, and is suitable for corresponding existing button battery or square battery structure.

[0017] In one possible implementation, the electrolyte includes lithium bis(trifluoromethanesulfonyl)imide, lithium nitrate, 1,3-dioxolane, and ethylene glycol dimethyl ether.

[0018] In the above technical solution, lithium bis(trifluoromethanesulfonic acid)imide, lithium nitrate, 1,3-dioxolane and ethylene glycol dimethyl ether are common components of lithium-sulfur battery electrolytes. The use of this combination of electrolytes can effectively simulate the conversion effect of catalysts in lithium-sulfur batteries on polysulfides.

[0019] In a possible implementation, the separator includes one of a cellulose separator, a polyethylene separator, a polypropylene separator, an aramid film, or a polyester film.

[0020] In the above technical solutions, these diaphragms have good stability and good mechanical properties, which can ensure the reliability of the test results.

[0021] In a possible implementation, the thickness of the separator is 10 μm to 30 μm.

[0022] In the above technical solution, the separator has an appropriate thickness to ensure ion transport and, to a certain extent, suppress side reactions within the battery. Furthermore, the appropriate thickness maintains the stability of the battery structure and effectively separates the electrolytic chamber into the positive and negative electrode chambers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0024] Figure 1This is a structural schematic diagram of a lithium-sulfur battery catalyst performance testing system provided in an embodiment of the present application.

[0025] Figure 2 This is a cyclic voltammetry curve diagram of the lithium-sulfur battery catalyst performance test system provided in Example 1 of the present application.

[0026] Figure 3 This is a cyclic voltammetry curve diagram of the lithium-sulfur battery catalyst performance test system provided in Example 2 of the present application.

[0027] Description of reference numerals:

[0028] 100 - electrochemical test device; 10 - positive electrode; 12 - positive electrode current collector layer; 20 - negative electrode; 22 - negative electrode current collector layer; 30 - electrolysis chamber; 32 - positive electrode chamber; 34 - negative electrode chamber; 40 - diaphragm; 200 - catalyst layer to be tested. DETAILED DESCRIPTION

[0029] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in this application and in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0031] In the description of this application, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the utility model product is usually placed when in use. It is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on this application.

[0032] In addition, the terms "first", "second", etc., if used, are merely used to distinguish and describe, and should not be understood as indicating or implying relative importance.

[0033] Lithium-sulfur batteries have high theoretical mass energy density (2600Wh / kg) and volume energy density (2200Wh / L), and the electrode materials are abundant, cheap, and environmentally friendly. Lithium-sulfur batteries are usually composed of a sulfur positive electrode, a separator, a lithium negative electrode, an electrolyte, and a current collector. The charging and discharging principle is the back-and-forth conversion of sulfur to polysulfide to lithium sulfide; the discharge process is the reaction of S8 and Li to form Li2S, and the charging process is the conversion of Li2S to S8. Many intermediate products are generated during the reaction, namely polysulfide (Li2S x Liquid polysulfides are easily soluble in the electrolyte, and some conversion reactions have poor kinetics. Driven by the electric field and the concentration gradient difference on both sides of the separator, polysulfides are generated on the sulfur side and dissolved in the electrolyte. They then pass through the separator to the lithium side, causing a severe shuttle effect. Finally, they are converted into Li2S and Li2S2 and deposited on the lithium negative electrode side. This leads to low sulfur utilization, poor cycle stability, and safety hazards in lithium-sulfur batteries, hindering their commercial application.

[0034] In recent years, a variety of catalysts have been applied to lithium-sulfur batteries to reduce the x The activation energy of conversion to Li2S is reduced x accumulation and shuttling, improving Li2S x To convert to Li2S, improve battery capacity and cycle stability. In order to quickly evaluate the conversion effect of catalysts on polysulfides and screen out efficient catalysts, current research is mainly based on the following two types of technologies: (1) Conventional electrochemical test equipment: using a standard three-electrode system (working electrode, counter electrode, reference electrode), through cyclic voltammetry (CV), constant current charge and discharge and other test methods, indirectly infer the kinetic effect of catalysts on polysulfide conversion. However, in this scheme, due to the uncontrollable diffusion path of sulfur species and the inability to simulate the synergistic effect of the dynamic migration of sulfur cathode and polysulfides in real batteries, it is difficult to analyze the regulation mechanism of catalysts on multi-step reactions. (2) Symmetrical battery: the same catalyst is coated on two identical symmetrical electrodes, and polysulfide electrolyte is injected for constant current charge and discharge or impedance testing. However, in this scheme, the sulfur dissolution-deposition behavior occurs symmetrically on both sides, making it impossible to distinguish the differential contributions of the catalyst in the sulfur reduction (e.g., S8→Li2S6) and the deep conversion of polysulfides (e.g., Li2S6→Li2S2). This results in the averaging of kinetic parameters (such as activation energy and overpotential). Therefore, it is necessary to propose a new lithium-sulfur battery catalyst performance testing system to better evaluate catalyst performance.

[0035] Based on this, the present invention provides a lithium-sulfur battery catalyst performance testing system for evaluating the performance of lithium-sulfur battery catalysts. Figure 1 This is a structural diagram of a lithium-sulfur battery catalyst performance test system provided in the embodiment of the present application, see Figure 1 The lithium-sulfur battery catalyst performance test system includes an electrochemical testing device 100 and a catalyst layer 200 to be tested. The electrochemical testing device 100 includes a positive electrode 10, a negative electrode 20, an electrolysis chamber 30 and a diaphragm 40. The electrolysis chamber 30 is provided with an electrolyte, and the electrolyte contains polysulfide. The positive electrode 10 and the negative electrode 20 are arranged on opposite sides of the electrolysis chamber 30. The diaphragm 40 is arranged in the electrolysis chamber 30 and is located between the positive electrode 10 and the negative electrode 20.

[0036] The positive electrode 10 includes a positive electrode current collector layer 12 . The negative electrode 20 includes a negative electrode current collector layer 22 . The catalyst layer 200 to be tested is disposed on the surface of the negative electrode current collector layer 22 facing the positive electrode current collector layer 12 .

[0037] In traditional symmetrical cells used for lithium-sulfur battery catalyst performance testing, the catalyst to be tested is set on both sides. The catalysts on both sides participate in the reaction simultaneously, resulting in coupled oxidation and reduction current signals, making it impossible to distinguish the contribution of the catalyst on one side. In this application, by designing the positive electrode 10 as a blank electrode (i.e., only including the positive electrode current collector layer 12), and setting the catalyst layer 200 to be tested on the negative electrode 20 side, an asymmetric single-sided catalytic structure is formed. The oxidation reaction (such as Li2S2→Li2S6) can be confined to the positive electrode 10 side, while the reduction reaction (such as Li2S6→Li2S2) is concentrated on the negative electrode 20 side. This allows the kinetic parameters (such as overpotential and Tafel slope) of the two reaction paths to be directly separated in the electrochemical test, and the oxidation and reduction abilities of the catalyst to be tested for polysulfides can be independently tested and evaluated.

[0038] In addition, although the traditional symmetrical cell has a catalyst layer to be tested on both sides, a single test can only evaluate one material. In this application, a single-sided catalytic design allows only the catalytic side electrode (i.e., the negative electrode 20) to be replaced in a single experiment, and the non-catalytic side (i.e., the positive electrode 10) remains blank, which increases the test flux by at least 2 times. By adjusting the types of polysulfides in the electrolyte on both sides (such as Li2S8 / Li2S4 or Li2S6 / Li2S2), the selective catalytic ability of the catalyst for different conversion steps (long chain → medium chain or medium chain → short chain) can be studied in a targeted manner. For example, if Li2S8 is injected into the negative electrode 20 and Li2S4 is injected into the positive electrode 10, the activity of the catalyst to be tested for the S8→S4 reduction reaction can be focused on, while traditional methods cannot achieve such targeted analysis.

[0039] Please continue to see Figure 1 In some embodiments, the diaphragm 40 separates the electrolysis chamber 30 into a positive electrode chamber 32 and a negative electrode chamber 34. The positive electrode 10, the diaphragm 40 and a portion of the inner wall of the electrolysis chamber 30 form the positive electrode chamber 32, and the negative electrode 20, the diaphragm 40 and another portion of the inner wall of the electrolysis chamber 30 form the negative electrode chamber 34.

[0040] By providing a diaphragm 40 to form physical isolation, interference with the test signal caused by side reactions at the opposite electrode (such as electrolyte decomposition) is avoided. For example, due to the lack of catalytic activity, the oxidation reaction current of the positive electrode 10 is significantly lower than that of the negative electrode 20, which greatly improves the data purity on the catalytic side.

[0041] In some embodiments, the thickness of the catalyst layer 200 to be tested is 10 μm to 15 μm. As an example, the thickness of the catalyst layer 200 to be tested is 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or a range between any two of the above values. By controlling the thickness of the catalyst layer to be tested within a suitable range, the corresponding loading amount of the catalyst to be tested is within a suitable range, which can provide sufficient active sites for the electrochemical reaction. The moderate thickness can effectively adsorb and catalyze polysulfides, and the polarization internal resistance is small, which can enable the electrochemical reaction to proceed efficiently.

[0042] In some embodiments, the catalyst layer 200 to be tested includes a catalyst to be tested and a binder, wherein the binder may be polyvinylidene fluoride (PVDF).

[0043] It should be noted that mixing the catalyst to be tested and the binder as the catalyst layer 200 to be tested is a common technology in this field and is not an improvement made in this application. For example, Chinese patent application CN119565582A discloses "mixing the catalyst and the binder in a suitable proportion, uniformly coating the resulting slurry on the current collector, drying and cutting to obtain symmetrical battery electrodes."

[0044] It is understood that the catalyst to be tested can be attached to one side of the negative electrode current collector layer 22 using a binder and then dried to form the catalyst layer 200 to be tested. Compared to applying the catalyst to be tested directly to the surface of the negative electrode current collector layer 22, forming the catalyst layer to be tested by mixing the catalyst to be tested and the binder can make the catalyst evenly distributed, providing more evenly distributed active sites for the battery reaction and firmly bonding to the current collector.

[0045] In other embodiments, the catalyst to be tested may be dispersed and then directly added dropwise to one side surface of the negative electrode current collector layer 22 , and then dried to form the catalyst layer 200 to be tested.

[0046] In the embodiments of the present application, the types and thicknesses of the positive electrode current collector layer 12 and the negative electrode current collector layer 22 are not specifically limited, and any current collector used in conventional symmetrical batteries can be used.

[0047] In some embodiments, the positive electrode current collector layer 12 and the negative electrode current collector layer 22 can each be independently selected from carbon paper or aluminum foil. In other embodiments, they can also be carbon-coated aluminum foil. These current collector materials all have good chemical stability and corrosion resistance.

[0048] In some embodiments, the thickness of the positive electrode current collector layer 12 and the negative electrode current collector layer 22 is independently 10 μm to 20 μm, for example, 10 μm, 12 μm, 15 μm, 16 μm, 20 μm, etc. A thickness within a suitable range can provide an appropriate surface area and mechanical support, enabling a stable structure during battery preparation and use. This can withstand volume changes during charge and discharge, provide reliable support for the electrodes, ensure electrode integrity and stability, and help improve the battery's cycle life and safety.

[0049] In the embodiments of the present application, the shapes of the positive electrode 10 and the negative electrode 20 are not specifically limited. The positive electrode 10 and the negative electrode 20 can each be independently circular or square, or other conventional shapes. Circular or square electrode sheets are convenient for processing by stamping or cutting, and are suitable for use with existing button cell or square battery structures.

[0050] In the embodiments of the present application, there is no specific limitation on the electrolyte, and any conventional electrolyte used for lithium-sulfur batteries can be applied to the present application.

[0051] In some embodiments, the electrolyte includes lithium bis(trifluoromethanesulfonimide) (LiTFSI), lithium nitrate (LiNO 3 ), 1,3-dioxolane (DOL), and ethylene glycol dimethyl ether (DME).

[0052] It should be noted that the above electrolyte composition is a common composition for lithium-sulfur battery electrolytes and is not an improvement to the mixture made by this application. For example, Chinese patent application CN119565582A discloses a lithium-sulfur battery electrolyte (a mixed solution of 1M lithium bistrifluoromethanesulfonyl imide (LiTFSI) and 1% lithium nitrate (LiNO3) in 1,3-dioxolane (DOL) and ethylene glycol dimethyl ether (DME) (1:1 volume ratio)).

[0053] In the embodiment of the present application, the type and thickness of the separator 40 are not specifically limited, and any separator used for lithium-sulfur batteries can be used.

[0054] In some embodiments, the separator 40 includes a cellulose separator, a polyethylene separator, a polypropylene separator, an aramid film, or a polyester film; and the thickness of the separator 40 is 10 μm to 30 μm. For example, the separator may be celgard 2500 with a thickness of 25 μm.

[0055] These separators 40 all possess good stability and mechanical properties, ensuring the reliability of test results. Furthermore, at an appropriate thickness, they ensure ion transport and, to a certain extent, suppress side reactions within the battery. Furthermore, this appropriate thickness maintains the stability of the battery structure and effectively separates the electrolytic chambers into the positive electrode chamber 32 and the negative electrode chamber 34.

[0056] The assembly process of the lithium-sulfur battery catalyst performance testing system of the present application may include the following steps:

[0057] (1) Take the positive electrode current collector layer 12 and the negative electrode current collector layer 22 and cut them into a predetermined size and shape (for example, a disc with a diameter of 12 mm) to serve as the positive electrode 10 and the negative electrode 20, respectively.

[0058] (2) The catalyst to be tested and the binder are mixed in a certain proportion, coated on one side of the negative electrode current collector layer 22, and vacuum dried at a certain temperature (e.g., 60°C to 80°C) to form the catalyst layer 200 to be tested.

[0059] (3) The positive electrode 10 and the negative electrode 20 are installed in the positive electrode chamber 32 and the negative electrode chamber 34 respectively, and the separator 40 is placed between the positive electrode chamber 32 and the negative electrode chamber 34 to ensure that the separator 40 is completely isolated.

[0060] (4) Inject appropriate amounts of electrolyte into the positive electrode chamber 32 and the negative electrode chamber 34 through the injection port, respectively. The polysulfide contained in the electrolyte is added according to the test requirements.

[0061] (5) Install the battery housing and seal the package to obtain the lithium-sulfur battery catalyst performance test system.

[0062] As an example, the lithium-sulfur battery catalyst performance testing system of the present application can be tested using the following method:

[0063] Add a low concentration of polysulfide Li2S to the electrolyte on the positive electrode 10 side (i.e., the positive electrode chamber 32) x-1 , a high concentration of polysulfide Li2S is added to the electrolyte on the negative electrode 20 side (ie, the negative electrode chamber 34) x (2<x≤8). The positive electrode 10 is connected to the anode of a power supply, and the negative electrode 20 is connected to the cathode of a power supply, and a cyclic voltammetry (CV) test is performed using an electrochemical workstation.

[0064] During the charge and discharge process, polysulfides diffuse and migrate through the pores of the diaphragm 40 driven by the concentration gradient, and a reduction reaction of high-order to low-order polysulfides occurs on the negative electrode 20 side (Li2S x →Li2S x-1 ), the positive electrode 10 undergoes a reverse oxidation reaction (Li2S x-1 →Li2S x By comparing the polarization voltage, reaction current and other parameters of the two electrodes, the catalytic efficiency of the catalyst to be tested for a specific conversion step can be quantitatively evaluated.

[0065] Example

[0066] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0067] Example 1

[0068] This embodiment provides a lithium-sulfur battery catalyst performance testing system, the assembly process includes the following steps:

[0069] (1) Take two identical sheets of carbon paper (10 μm thick) and cut them into a positive electrode and a negative electrode.

[0070] (2) The catalyst to be tested (nitrogen-doped carbon-loaded cobalt material, abbreviated as CO-NC) and the binder PVDF were mixed in a mass ratio of 9:1, coated on one side of the negative electrode carbon paper (thickness of 10 μm), and vacuum dried at 60 °C to form a catalyst layer to be tested (thickness of 12 μm).

[0071] (3) The positive electrode and the negative electrode are installed in the positive electrode chamber and the negative electrode chamber respectively, and the separator 40 is placed between the positive electrode chamber and the negative electrode chamber to ensure that the separator (Celgard 2500 with a thickness of 25 μm) is completely isolated.

[0072] (4) Through the injection port, inject an appropriate amount of electrolyte into the positive electrode chamber and the negative electrode chamber respectively. The electrolyte composition is a mixed solution of 1,3-dioxolane (DOL) and ethylene glycol dimethyl ether (DME) (volume ratio is 1:1) containing 1M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1wt% lithium nitrate (LiNO3). Among them, 20μL of 0.05MLi2S7 is added to the electrolyte of the positive electrode chamber, and 20μL of 0.1M Li2S8 is added to the electrolyte of the negative electrode chamber.

[0073] (5) Install the battery housing and seal it to obtain a lithium-sulfur battery catalyst performance test system.

[0074] Example 2

[0075] This embodiment provides a lithium-sulfur battery catalyst performance testing system. The assembly process differs from that of Example 1 in that:

[0076] The catalyst to be tested in step (2) is a nitrogen-doped carbon material, referred to as NC.

[0077] The lithium-sulfur battery catalyst performance test system in Example 1 and Example 2 was subjected to a cyclic voltammetry test with a voltage range of -1V to 1V.

[0078] Figure 2 This is a cyclic voltammetry curve of the lithium-sulfur battery catalyst performance test system provided in Example 1 of the present application. Figure 3 This is a cyclic voltammetry curve of the lithium-sulfur battery catalyst performance test system provided in Example 2 of this application. Figure 2 and Figure 3 It can be seen that Figure 2 The reduction peak in is sharper and larger, indicating that CO-NC has a stronger reducing ability for Li2S8.

[0079] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A lithium-sulfur battery catalyst performance testing system, characterized in that: The device comprises a catalyst layer to be tested and an electrochemical testing device, wherein the electrochemical testing device comprises a positive electrode, a negative electrode, a diaphragm and an electrolysis chamber, wherein an electrolyte is provided in the electrolysis chamber, and the electrolyte contains polysulfide; the positive electrode and the negative electrode are arranged on opposite sides of the electrolysis chamber, and the diaphragm is arranged in the electrolysis chamber and located between the positive electrode and the negative electrode; The positive electrode includes a positive electrode current collector layer, the negative electrode includes a negative electrode current collector layer, and the catalyst layer to be tested is arranged on the surface of the negative electrode current collector layer facing the positive electrode current collector layer.

2. The lithium-sulfur battery catalyst performance testing system according to claim 1, characterized in that: The diaphragm separates the electrolysis chamber into a positive electrode chamber and a negative electrode chamber. The positive electrode, the diaphragm and part of the inner wall of the electrolysis chamber form the positive electrode chamber, and the negative electrode, the diaphragm and another part of the inner wall of the electrolysis chamber form the negative electrode chamber.

3. The lithium-sulfur battery catalyst performance testing system according to claim 1, characterized in that: The thickness of the catalyst layer to be tested is 10 μm to 15 μm.

4. The lithium-sulfur battery catalyst performance testing system according to claim 1, characterized in that: The catalyst layer to be tested includes a catalyst to be tested and a binder.

5. The lithium-sulfur battery catalyst performance testing system according to claim 1, characterized in that: The positive electrode current collector layer and the negative electrode current collector layer are each independently selected from carbon paper or aluminum foil.

6. The lithium-sulfur battery catalyst performance testing system according to claim 5, characterized in that: The thickness of the positive electrode current collector layer and the negative electrode current collector layer are each independently 10 μm to 20 μm.

7. The lithium-sulfur battery catalyst performance testing system according to claim 1, characterized in that: The positive electrode and the negative electrode are each independently circular or square in shape.

8. The lithium-sulfur battery catalyst performance testing system according to claim 1, characterized in that: The electrolyte includes lithium bis(trifluoromethanesulfonyl)imide, lithium nitrate, 1,3-dioxolane and ethylene glycol dimethyl ether.

9. The lithium-sulfur battery catalyst performance testing system according to claim 1, characterized in that: The separator includes one of a cellulose separator, a polyethylene separator, a polypropylene separator, an aramid film or a polyester film.

10. The lithium-sulfur battery catalyst performance testing system according to claim 9, characterized in that: The thickness of the separator is 10 μm to 30 μm.

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