Sandwich type sulfenyl positive plate, preparation method thereof and magnesium battery

Abstract

The invention provides an interlayer type sulfur-based positive plate. The interlayer type sulfur-based positive plate comprises a current collector, the active material layer is arranged on at least one side of the current collector; and the microporous copper-based layer is arranged on the active material layer. The metal or metal alloy foil is adopted to replace traditional copper foil to serve as the current collector, the active material layer and the copper net or the copper foil with the micropore structure are sequentially arranged on the surface of the current collector, an integrated composite electrode structure is formed, corrosion caused when the sulfur-based positive plate uses a Cu current collector can be effectively avoided, and the service life of the sulfur-based positive plate is prolonged. And the problem of unstable interface contact caused by using a copper net as an independent intermediate layer is avoided. The sandwich type sulfur-based positive plate is used for the magnesium-sulfur battery, so that the conductivity of a system can be enhanced, the shuttle effect is inhibited, and the charge-discharge specific capacity and the cycle stability of the battery are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of magnesium battery technology, and relates to a sandwich-type sulfur-based positive electrode sheet and its preparation method, magnesium battery, and its application. Background Technology

[0002] With the rapid development of electric vehicles, portable devices, communications, and other fields, the market has placed higher demands on the energy density, safety, and cost of batteries. Magnesium metal anodes possess extremely high theoretical specific capacity (volume specific capacity of 3833 mAh / cm³). 3 With its outstanding advantages such as a specific capacity of 2205 mAh / g, low dendrite formation, and abundant natural reserves, magnesium batteries have become a research hotspot for novel energy storage systems. Currently, magnesium batteries can be classified into various types based on their cathode materials. Among them, sulfur cathode materials possess advantages such as high specific capacity (1675 mAh / g), high energy density (2600Wh / kg), environmental friendliness, low cost, and abundant natural reserves, making them more suitable for large-scale energy storage applications.

[0003] However, the aluminum current collector in magnesium-sulfur batteries exhibits poor electrochemical activity, and the polysulfides readily dissolve and generate a shuttle effect during cycling, leading to rapid capacity decay and thus hindering their market application. Therefore, current electrode modification strategies for magnesium-sulfur batteries still cannot meet practical application requirements, and more effective solutions urgently need to be developed.

[0004] Therefore, finding a more suitable electrode for magnesium-sulfur batteries and solving the aforementioned technical problems of existing magnesium-sulfur batteries has become one of the urgent problems to be solved by many front-line researchers in the industry. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a sandwich-type sulfur-based cathode sheet, its preparation method, a magnesium battery, and its application. The sandwich-type sulfur-based cathode sheet provided by the present invention improves the discharge specific capacity and cycle stability of magnesium-sulfur batteries, thereby solving the problems of poor electrochemical activity and shuttle effect of sulfur cathodes in existing magnesium-sulfur batteries.

[0006] This invention provides a sandwich-type sulfur-based positive electrode, wherein the sandwich-type sulfur-based positive electrode includes a current collector;

[0007] An active material layer disposed on at least one side of the current collector;

[0008] A microporous copper substrate is disposed on the active material layer.

[0009] Preferably, the current collector includes a non-copper-based current collector;

[0010] The thickness of the current collector is 6~20μm;

[0011] The active material layer includes a sulfur-based cathode material;

[0012] The thickness of the active material layer is 50~400μm.

[0013] Preferably, the current collector includes one or more of the following: titanium foil, coated titanium foil, titanium alloy foil, nickel foil, coated nickel foil, nickel alloy foil, stainless steel foil, coated stainless steel foil, stainless steel alloy foil, vanadium foil, coated vanadium foil, vanadium alloy foil, zinc foil, coated zinc foil, zinc alloy foil, aluminum foil, coated aluminum foil, and aluminum alloy foil;

[0014] The microporous copper substrate includes copper mesh and / or copper foil;

[0015] The microporous copper substrate is made of copper and / or copper alloys;

[0016] The thickness of the microporous copper substrate is 1~20μm.

[0017] Preferably, the pore size of the microporous copper substrate is 10 to 1000 mesh;

[0018] The active material layer includes a sulfur-based cathode material, a conductive agent, and a binder;

[0019] The sulfur-based cathode material includes a support and M composite on the support. x S 1-x Where M is Se or Te, 0≤x≤0.4.

[0020] Preferably, the carrier comprises one or more of carbon-based materials, polymer-based materials, and polar inorganic materials;

[0021] The mass content of sulfur-based cathode material in the active material layer is 70%~90%;

[0022] The mass content of the conductive agent in the active material layer is 5%~15%;

[0023] The sandwich-type sulfur-based cathode sheet is a cathode sheet used in magnesium-sulfur batteries.

[0024] The present invention also provides a method for preparing a sandwich-type sulfur-based positive electrode sheet as described in any of the above technical solutions, comprising the following steps:

[0025] The active material slurry is coated onto the current collector. After coating, a microporous copper base layer is laid on the wet coating of the active material. After drying and rolling, a sandwich sulfur-based positive electrode is obtained.

[0026] Preferably, the preparation process of the active material layer slurry includes the following steps:

[0027] After ball milling and mixing sulfur-based cathode material, conductive agent, binder and solvent, an active material layer slurry is obtained;

[0028] The conductive agent includes one or more of carbon black, Super-P, acetylene black, graphene, and carbon nanotubes.

[0029] The adhesive includes one or more of carboxymethyl cellulose, styrene-butadiene rubber, polytetrafluoroethylene, polyacrylic acid, polyvinylidene fluoride and acrylonitrile copolymer;

[0030] The solvent includes one or more of ethanol, ethylene glycol dimethyl ether, water, or N-methylpyrrolidone.

[0031] Preferably, in the active material layer slurry, the mass content of the sulfur-based cathode material is 70% to 90%;

[0032] In the active material layer slurry, the mass content of the conductive agent is 5%~15%;

[0033] The solid content of the active material layer slurry is 10%~40%;

[0034] The drying temperature is 40~100℃;

[0035] The drying time is 8 to 24 hours.

[0036] The present invention also provides a magnesium battery, comprising a sandwich-type sulfur-based positive electrode sheet as described in any one of the above technical solutions or a sandwich-type sulfur-based positive electrode sheet prepared by any one of the above technical solutions.

[0037] The present invention also provides the application of the sandwich-type sulfur-based positive electrode sheet described in any one of the above technical solutions or the sandwich-type sulfur-based positive electrode sheet prepared by the preparation method described in any one of the above technical solutions in metal sulfur-based batteries.

[0038] This invention provides a sandwich-type sulfur-based cathode, comprising a current collector; an active material layer disposed on at least one side of the current collector; and a microporous copper substrate disposed on the active material layer. Compared to existing technologies, although current research has demonstrated that using copper metal in the sulfur cathode can significantly improve the cycle stability of magnesium-sulfur batteries, and most current approaches involve introducing copper foil as the current collector or using copper foam or copper mesh as an independent interlayer inserted between the separator and the electrode, this invention argues that these technical solutions have certain limitations: firstly, copper current collectors are prone to corrosion, causing active material detachment; secondly, copper foam has a large volume, limiting the battery's energy density; furthermore, copper mesh as an independent interlayer suffers from unstable interfacial contact and is prone to displacement, all of which are detrimental to its practical application in magnesium-sulfur batteries. Therefore, current sulfur cathode modification strategies for magnesium-sulfur batteries still cannot meet practical application requirements, and more effective solutions are urgently needed.

[0039] Based on this, the present invention creatively designs a sandwich-type sulfur-based positive electrode with a specific structure and composition. The present invention uses metal or metal alloy foil instead of traditional copper foil as the non-copper current collector. An active material layer is sequentially coated on the surface of the current collector, followed by the deposition of a copper mesh or copper foil with a microporous structure, forming an integrated composite electrode structure. This effectively solves the problem of current collector corrosion and avoids issues such as unstable interfacial contact during cycling and easy displacement during stacking when the copper mesh exists as an independent intermediate layer. Furthermore, the sandwich-type sulfur-based positive electrode designed in this invention uses M... x S 1-x As an active material in sulfur-based cathodes, it can improve its own conductivity. At the same time, copper mesh or copper foil with microporous structure can adsorb and catalyze polysulfides, suppress shuttle effect, and synergistically improve the performance of magnesium-sulfur batteries.

[0040] The present invention also provides a corresponding method for preparing sandwich-type sulfur-based positive electrode sheets. The preparation process is simple and efficient, with low cost and no special treatment required, making it suitable for large-scale commercial production and use.

[0041] Experimental results show that the sandwich-type sulfur-based cathode provided by this invention, when applied to magnesium-sulfur batteries, has an initial discharge specific capacity as high as 1373 mAh / g, and after 15 cycles at 0.1C, the capacity retention rate is >100%, exhibiting excellent cycle stability that has not been previously reported. Attached Figure Description

[0042] Figure 1 The specific capacity-voltage curves are shown for the sandwich-type sulfur-based positive electrode sheet prepared in Example 1 of the present invention and the sulfur-based positive electrode sheet prepared in Comparative Example 1.

[0043] Figure 2The specific capacity-voltage curves of the sandwich-type sulfur-based positive electrode prepared in Example 2 of the present invention and the sulfur-based positive electrode prepared in Comparative Example 2 are shown.

[0044] Figure 3 The specific capacity-voltage curves are shown for the sandwich-type sulfur-based positive electrode sheet prepared in Example 3 of the present invention and the sulfur-based positive electrode sheet prepared in Comparative Example 3.

[0045] Figure 4 The specific capacity-voltage curves of the sandwich-type sulfur-based positive electrode prepared in Example 4 of the present invention and the sulfur-based positive electrode prepared in Comparative Example 4 are shown.

[0046] Figure 5 Electrochemical impedance spectroscopy (EIS) of the sandwich-type sulfur-based cathode prepared in Example 4 and the sandwich-type sulfur-based cathode prepared in Example 5 of this invention.

[0047] Figure 6 The diagram shows the cycle performance of the sandwich-type sulfur-based positive electrode prepared in Example 4 of this invention. Detailed Implementation

[0048] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention and not for limiting the claims of the present invention.

[0049] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0050] The purity of all raw materials used in this invention is not particularly limited. However, this invention preferably uses analytical grade or the purity requirements conventional in the field of sulfur battery cathode material preparation.

[0051] All raw materials of this invention are conventional in the field, and each brand name and abbreviation is clear and distinct in its relevant application. Those skilled in the art can purchase them from the market or prepare them by conventional methods based on the brand name, abbreviation and corresponding application.

[0052] The processes used in this invention are all commonly referred to in the field. The specific steps and conventional parameters of each abbreviation are clear and well-defined in their respective fields. Those skilled in the art can implement them using conventional methods based on the abbreviations.

[0053] This invention provides a sandwich-type sulfur-based positive electrode, wherein the sandwich-type sulfur-based positive electrode includes a current collector;

[0054] An active material layer disposed on at least one side of the current collector;

[0055] A microporous copper substrate is disposed on the active material layer.

[0056] In this invention, the current collector preferably includes a non-copper-based current collector.

[0057] In this invention, the thickness of the current collector can be 6~20μm, or 8~18μm, or 10~15μm.

[0058] In this invention, the active material layer preferably includes a sulfur-based cathode material.

[0059] In this invention, the thickness of the active material layer can be 50~400μm, or 100~350μm, or 150~300μm, or 200~250μm.

[0060] In this invention, the current collector preferably includes one or more of the following: titanium foil, coated titanium foil, titanium alloy foil, nickel foil, coated nickel foil, nickel alloy foil, stainless steel foil, coated stainless steel foil, stainless steel alloy foil, vanadium foil, coated vanadium foil, vanadium alloy foil, zinc foil, coated zinc foil, zinc alloy foil, aluminum foil, coated aluminum foil, and aluminum alloy foil. More preferably, it is titanium foil, coated titanium foil, titanium alloy foil, nickel foil, coated nickel foil, nickel alloy foil, stainless steel foil, coated stainless steel foil, stainless steel alloy foil, vanadium foil, coated vanadium foil, vanadium alloy foil, zinc foil, coated zinc foil, zinc alloy foil, aluminum foil, coated aluminum foil, or aluminum alloy foil.

[0061] In this invention, the microporous copper substrate can be considered as a copper-based material mesh. Specifically, it can be a copper mesh and / or copper foil.

[0062] In this invention, the material of the microporous copper substrate may include copper and / or copper alloy.

[0063] The copper mesh of the microporous copper substrate preferably includes pure copper mesh and / or alloy copper mesh, more preferably pure copper mesh or alloy copper mesh.

[0064] In this invention, the thickness of the microporous copper substrate can be 1~20μm, 5~16μm, or 9~12μm.

[0065] In this invention, the mesh size of the microporous copper substrate can be 10~1000 mesh, 200~800 mesh, or 400~600 mesh.

[0066] In this invention, the active material layer preferably includes a sulfur-based cathode material, a conductive agent, and a binder.

[0067] In this invention, the sulfur-based cathode material preferably includes a support and M composited on the support. x S 1-xWhere M is Se or Te, 0≤x≤0.4. Specifically, it can be 0.05≤x≤0.35, 0.1≤x≤0.3, or 0.15≤x≤0.25.

[0068] In this invention, the carrier preferably includes one or more of carbon-based materials, polymer-based materials, and polar inorganic materials, and more preferably carbon-based materials, polymer-based materials, or polar inorganic materials.

[0069] In this invention, the mass content of sulfur-based cathode material in the active material layer can be 70%~90%, 74%~86%, or 78%~82%.

[0070] In this invention, the mass content of the conductive agent in the active material layer can be 5%~15%, 7%~13%, or 9%~11%.

[0071] In this invention, the sandwich-type sulfur-based cathode sheet is preferably a cathode sheet used in magnesium-sulfur batteries.

[0072] This invention provides a method for preparing a sandwich-type sulfur-based positive electrode sheet as described in any of the above technical solutions, comprising the following steps:

[0073] The active material slurry is applied to the current collector. After the coating is completed, a microporous copper substrate (copper mesh or copper foil) is laid on the wet coating of the active material. After drying and rolling, a sandwich sulfur-based positive electrode is obtained.

[0074] In this invention, the preparation process of the active material layer slurry preferably includes the following steps:

[0075] A slurry of active material layer is obtained by ball milling and mixing sulfur-based cathode material, conductive agent, binder and solvent.

[0076] In this invention, the conductive agent preferably includes one or more of carbon black, Super-P, acetylene black, graphene and carbon nanotubes, and more preferably carbon black, Super-P, acetylene black, graphene or carbon nanotubes.

[0077] In this invention, the adhesive preferably includes one or more of carboxymethyl cellulose, styrene-butadiene rubber, polytetrafluoroethylene, polyacrylic acid, polyvinylidene fluoride and acrylonitrile copolymer, more preferably carboxymethyl cellulose, styrene-butadiene rubber, polytetrafluoroethylene, polyacrylic acid, polyvinylidene fluoride or acrylonitrile copolymer.

[0078] In this invention, the solvent preferably includes one or more of ethanol, ethylene glycol dimethyl ether, water or N-methylpyrrolidone, more preferably ethanol, ethylene glycol dimethyl ether, water or N-methylpyrrolidone.

[0079] In this invention, the mass content of sulfur-based cathode material in the active material layer slurry can be 70%~90%, 74%~86%, or 78%~82%.

[0080] In this invention, the mass content of the conductive agent in the active material layer slurry can be 5%~15%, 7%~13%, or 9%~11%.

[0081] In this invention, the solid content of the active material layer slurry can be 10%~40%, or 15%~35%, or 20%~30%.

[0082] In this invention, the drying temperature can be 40~100℃, 50~90℃, or 60~80℃.

[0083] In this invention, the drying time can be 8 to 24 hours, 11 to 21 hours, or 14 to 17 hours.

[0084] This invention provides a magnesium battery, comprising a sandwich-type sulfur-based positive electrode sheet as described in any one of the above technical solutions or a sandwich-type sulfur-based positive electrode sheet prepared by any one of the above technical solutions.

[0085] This invention provides the application of the sandwich-type sulfur-based positive electrode sheet described in any one of the above technical solutions or the sandwich-type sulfur-based positive electrode sheet prepared by the preparation method described in any one of the above technical solutions in metal sulfur-based batteries.

[0086] It should be noted that all batteries mentioned in this invention are secondary batteries or energy storage batteries.

[0087] In this invention, the metal sulfur-based battery can be a Li-S battery, a Na-S battery, a KS battery, a Ca-S battery, a Mg-S battery, or an Al-S battery, more preferably a Mg-S battery.

[0088] This invention replaces traditional copper foil with metal or metal alloy foil as the current collector. An active material layer and a copper mesh or copper foil with a microporous structure are sequentially deposited on the surface of the current collector, forming an integrated composite electrode structure. This effectively solves the corrosion problem faced by sulfur-based cathode sheets using Cu current collectors and avoids the interfacial contact instability issues associated with copper mesh as an independent intermediate layer. The sandwich-type sulfur-based cathode sheet of this invention, when used in magnesium-sulfur batteries, enhances the system's conductivity and suppresses the shuttle effect, significantly improving the battery's charge-discharge specific capacity and cycle stability.

[0089] This invention aims to complete and refine the overall technical solution, better ensure the composition and structure of the sandwich-type sulfur-based cathode sheet, and further improve the electrical performance of the sandwich-type sulfur-based cathode sheet in batteries. Specifically, the aforementioned sandwich-type sulfur-based cathode sheet, its preparation method, magnesium batteries, and applications may include the following:

[0090] A sandwich-type sulfur-based positive electrode includes a current collector and an active material layer and a microporous copper substrate disposed on one side of the current collector.

[0091] Specifically, the current collector is one of the following: titanium foil, coated titanium foil, titanium alloy foil, nickel foil, coated nickel foil, nickel alloy foil, stainless steel foil, coated stainless steel foil, stainless steel alloy foil, vanadium foil, coated vanadium foil, vanadium alloy foil, zinc foil, coated zinc foil, zinc alloy foil, aluminum foil, coated aluminum foil, and aluminum alloy foil.

[0092] Specifically, the active material layer is made of a sulfur-based cathode material, a conductive agent, and a binder, wherein the sulfur-based cathode material is composed of M x S 1-x It consists of a carrier, wherein the carrier is at least one of carbon-based materials, polymer-based materials, and polar inorganic materials, M is Se or Te, and 0≤x≤0.4.

[0093] Specifically, the coated microporous copper substrate is one of pure copper mesh (or pure copper foil) or alloy copper mesh (or alloy copper foil), wherein the mesh number of the copper mesh (or copper foil) is 10~1000 mesh and the thickness is 1~20μm.

[0094] This invention provides a method for preparing a sandwich-type sulfur-based positive electrode sheet as described in one of the above-mentioned technical solutions, comprising the following steps:

[0095] (1) Mix sulfur-based cathode material, conductive agent and binder in a certain proportion, add appropriate amount of solvent, and ball mill to obtain slurry;

[0096] (2) Apply the slurry to the current collector. After the coating is completed, lay the copper mesh or copper foil flat on the wet coating, dry and roll it to obtain the integrated composite electrode, which is the sandwich sulfur-based positive electrode sheet.

[0097] Specifically, the conductive agent is one or a mixture of several of carbon black, Super-P, acetylene black, graphene, and carbon nanotubes.

[0098] Specifically, the adhesive is one or a mixture of several of the following: carboxymethyl cellulose, styrene-butadiene rubber, polytetrafluoroethylene, polyacrylic acid, polyvinylidene fluoride, and acrylonitrile copolymer.

[0099] Specifically, the solvent is one or a mixture of several of ethanol, ethylene glycol dimethyl ether, deionized water, or N-methylpyrrolidone.

[0100] Specifically, the mass ratio of the sulfur-based cathode material, conductive agent, and binder is x:y:(100-xy), where x=70~90 and y=5~15.

[0101] Specifically, the drying temperature is 40~100℃, and the drying time is 8~24 hours.

[0102] The present invention also provides a magnesium battery, comprising a sandwich-type sulfur-based positive electrode sheet as described in any one of the above technical solutions or a sandwich-type sulfur-based positive electrode sheet prepared by any one of the above technical solutions.

[0103] The present invention provides a sandwich-type sulfur-based cathode sheet, its preparation method, a magnesium battery, and its application. This invention uses metal or metal alloy foil instead of traditional copper foil as the non-copper current collector. An active material layer is sequentially coated on the surface of the current collector, followed by the deposition of a copper mesh or copper foil with a microporous structure, forming an integrated composite electrode structure. This effectively solves the problem of current collector corrosion and avoids issues such as unstable interfacial contact during cycling and easy displacement during stacking when the copper mesh exists as an independent intermediate layer. Furthermore, the sandwich-type sulfur-based cathode sheet designed in this invention uses M... x S 1-x As an active material in sulfur-based cathodes, it can improve its own conductivity. At the same time, copper mesh or copper foil with microporous structure can adsorb and catalyze polysulfides, suppress shuttle effect, and synergistically improve the performance of magnesium-sulfur batteries.

[0104] The present invention also provides a corresponding method for preparing sandwich-type sulfur-based positive electrode sheets. The preparation process is simple and efficient, with low cost and no special treatment required, making it suitable for large-scale commercial production and use.

[0105] Experimental results show that the sandwich-type sulfur-based cathode provided by this invention, when applied to magnesium-sulfur batteries, has an initial discharge specific capacity as high as 1373 mAh / g, and after 15 cycles at 0.1C, the capacity retention rate is >100%, exhibiting excellent cycle stability that has not been previously reported.

[0106] To further illustrate the present invention, the following detailed description of a sandwich-type sulfur-based positive electrode sheet, its preparation method, magnesium battery, and applications provided by the present invention is provided in conjunction with embodiments. However, it should be understood that these embodiments are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are given only to further illustrate the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention. The scope of protection of the present invention is not limited to the following embodiments.

[0107] Example 1

[0108] Fabrication of a sandwich-type sulfur-based positive electrode and a magnesium battery containing the positive electrode:

[0109] Step 1: Mix 800 parts of commercial sulfur carbon, 100 parts of Super-P and 100 parts of carboxymethyl cellulose in a mass ratio of 80:10:10, grind evenly, and then add deionized water at a solid content of 20% to form a uniform slurry.

[0110] Step 2: Apply the above slurry to the nickel current collector. After coating, lay the copper mesh flat on the wet coating and dry it in a vacuum drying oven at 60°C for 12 hours. Then roll it with a roller press to obtain the sandwich sulfur-based positive electrode sheet.

[0111] Step 3: Preparation of magnesium battery containing the positive electrode: The sandwich-type sulfur-based positive electrode, glass fiber diaphragm, metallic magnesium or magnesium alloy negative electrode, and magnesium battery electrolyte prepared above are assembled into a button cell in a glove box, and then sealed with a hydraulic sealing machine to obtain a magnesium battery containing the positive electrode.

[0112] Example 2

[0113] Fabrication of a sandwich-type sulfur-based positive electrode and a magnesium battery containing the positive electrode:

[0114] The same preparation method as in Example 1 was used, except that the nickel current collector was replaced with a titanium current collector.

[0115] Example 3

[0116] Fabrication of a sandwich-type sulfur-based positive electrode and a magnesium battery containing the positive electrode:

[0117] The same preparation method as in Example 1 was used, except that the nickel current collector was replaced with a stainless steel current collector.

[0118] Example 4

[0119] Fabrication of a sandwich-type sulfur-based positive electrode and a magnesium battery containing the positive electrode:

[0120] The same preparation method as in Example 1 was used, except that the nickel current collector was replaced with an aluminum current collector.

[0121] Example 5

[0122] Fabrication of a sandwich-type sulfur-based positive electrode and a magnesium battery containing the positive electrode:

[0123] The same preparation method as in Example 4 was used, except that commercial sulfur-carbon (S / C) was replaced with a carbon-supported sulfur-selenium solid solution (Se). 0.4 S 0.6 / C).

[0124] Comparative Example 1

[0125] Preparation of a sulfur-based positive electrode and a magnesium battery containing the positive electrode:

[0126] The difference between Comparative Example 1 and Example 1 is that the sulfur-based cathode only includes a nickel current collector and an active material layer, but does not include a copper mesh layer. The other parameters are the same as those in Example 1.

[0127] Comparative Example 2

[0128] Preparation of a sulfur-based positive electrode and a magnesium battery containing the positive electrode:

[0129] The difference between Comparative Example 2 and Example 2 is that the sulfur-based cathode only includes a titanium current collector and an active material layer, but does not include a copper mesh layer. The other parameters are the same as those in Example 2.

[0130] Comparative Example 3

[0131] Preparation of a sulfur-based positive electrode and a magnesium battery containing the positive electrode:

[0132] The difference between Comparative Example 3 and Example 3 is that the sulfur-based positive electrode sheet only includes a stainless steel current collector and an active material layer, but does not include a copper mesh layer. The other parameters are the same as those in Example 3.

[0133] Comparative Example 4

[0134] Preparation of a sulfur-based positive electrode and a magnesium battery containing the positive electrode:

[0135] The difference between Comparative Example 4 and Example 4 is that the sulfur-based cathode sheet only includes an aluminum current collector and an active material layer, but does not include a copper mesh layer; the other parameters are the same as those in Example 4.

[0136] The magnesium batteries prepared in the embodiments and comparative examples of the present invention were tested.

[0137] The specific capacity-voltage curves of the sandwich-type sulfur-based cathode sheets prepared in Examples 1-4 and the sulfur-based cathode sheets prepared in Comparative Examples 1-4 are shown below. Figures 1-4 As shown.

[0138] See Figure 1 , Figure 1 The specific capacity-voltage curves are shown for the sandwich-type sulfur-based positive electrode prepared in Example 1 of the present invention and the sulfur-based positive electrode prepared in Comparative Example 1.

[0139] See Figure 2 , Figure 2 The specific capacity-voltage curves are shown for the sandwich-type sulfur-based positive electrode prepared in Example 2 of the present invention and the sulfur-based positive electrode prepared in Comparative Example 2.

[0140] See Figure 3 , Figure 3 The specific capacity-voltage curves are shown for the sandwich-type sulfur-based positive electrode prepared in Example 3 of the present invention and the sulfur-based positive electrode prepared in Comparative Example 3.

[0141] See Figure 4 , Figure 4 The specific capacity-voltage curves are shown for the sandwich-type sulfur-based positive electrode prepared in Example 4 of the present invention and the sulfur-based positive electrode prepared in Comparative Example 4.

[0142] The comparison shows that, regardless of the metal foil used to replace the traditional copper foil as the current collector, magnesium batteries containing sulfur-based cathodes without microporous copper substrates cannot be charged and discharged normally. However, sandwich-type sulfur-based cathodes with microporous copper substrates, using nickel, titanium, stainless steel, or aluminum as current collectors, all exhibit extremely high discharge specific capacity.

[0143] See Figure 5 , Figure 5 Electrochemical impedance spectroscopy (EIS) of the sandwich-type sulfur-based cathode prepared in Example 4 and the sandwich-type sulfur-based cathode prepared in Example 5 of this invention.

[0144] As can be seen from the electrochemical impedance spectroscopy of Examples 4 and 5, solid solution M was constructed by using selenium-doped sulfur, which has high conductivity and belongs to the same group as sulfur. x S 1-x As an active material in sulfur-based cathodes, it can significantly reduce the interfacial contact resistance of magnesium batteries, thereby providing good kinetic behavior and improving the cycle stability of sulfur cathode materials.

[0145] See Figure 6 , Figure 6 The diagram shows the cycle performance of the sandwich-type sulfur-based positive electrode prepared in Example 4 of this invention.

[0146] Cyclic performance tests of the sandwich-type sulfur-based cathode prepared in Example 4 showed that the magnesium battery containing this cathode had an initial discharge specific capacity of up to 1373 mAh / g at a 0.1C rate current, and after 15 cycles, the capacity retention rate was >100%, demonstrating extremely excellent sulfur utilization and cycle stability.

[0147] The foregoing has provided a detailed description of the sandwich-type sulfur-based positive electrode sheet, its preparation method, magnesium battery, and applications provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are merely for the purpose of helping to understand the method and core ideas of the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the textual description of the claims, or if they include equivalent structural elements that are not substantially different from the textual description of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A sandwich-type sulfur-based positive electrode, characterized in that, The sandwich-type sulfur-based positive electrode includes a current collector; An active material layer disposed on at least one side of the current collector; A microporous copper substrate is disposed on the active material layer.

2. The sandwich-type sulfur-based positive electrode according to claim 1, characterized in that, The current collector includes non-copper based current collectors; The thickness of the current collector is 6~20μm; The active material layer includes a sulfur-based cathode material; The thickness of the active material layer is 50~400μm.

3. The sandwich-type sulfur-based positive electrode according to claim 1, characterized in that, The current collector includes one or more of the following: titanium foil, coated titanium foil, titanium alloy foil, nickel foil, coated nickel foil, nickel alloy foil, stainless steel foil, coated stainless steel foil, stainless steel alloy foil, vanadium foil, coated vanadium foil, vanadium alloy foil, zinc foil, coated zinc foil, zinc alloy foil, aluminum foil, coated aluminum foil, and aluminum alloy foil. The microporous copper substrate includes copper mesh and / or copper foil; The microporous copper substrate is made of copper and / or copper alloys; The thickness of the microporous copper substrate is 1~20μm.

4. The sandwich-type sulfur-based positive electrode according to claim 1, characterized in that, The pore size of the microporous copper substrate is 10~1000 mesh; The active material layer includes a sulfur-based cathode material, a conductive agent, and a binder; The sulfur-based cathode material includes a support and M composite on the support. x S 1-x Where M is Se or Te, 0≤x≤0.

4.

5. The sandwich-type sulfur-based positive electrode according to claim 4, characterized in that, The carrier includes one or more of carbon-based materials, polymer-based materials, and polar inorganic materials; The mass content of sulfur-based cathode material in the active material layer is 70%~90%; The mass content of the conductive agent in the active material layer is 5%~15%; The sandwich-type sulfur-based cathode sheet is a cathode sheet used in magnesium-sulfur batteries.

6. A method for preparing a sandwich-type sulfur-based positive electrode sheet as described in any one of claims 1 to 5, characterized in that, Includes the following steps: The active material slurry is coated onto the current collector. After coating, a microporous copper base layer is laid on the wet coating of the active material. After drying and rolling, a sandwich sulfur-based positive electrode is obtained.

7. The preparation method according to claim 6, characterized in that, The preparation process of the active material layer slurry includes the following steps: After ball milling and mixing sulfur-based cathode material, conductive agent, binder and solvent, an active material layer slurry is obtained; The conductive agent includes one or more of carbon black, Super-P, acetylene black, graphene, and carbon nanotubes. The adhesive includes one or more of carboxymethyl cellulose, styrene-butadiene rubber, polytetrafluoroethylene, polyacrylic acid, polyvinylidene fluoride and acrylonitrile copolymer; The solvent includes one or more of ethanol, ethylene glycol dimethyl ether, water, or N-methylpyrrolidone.

8. The preparation method according to claim 7, characterized in that, In the active material layer slurry, the mass content of the sulfur-based cathode material is 70%~90%; In the active material layer slurry, the mass content of the conductive agent is 5%~15%; The solid content of the active material layer slurry is 10%~40%; The drying temperature is 40~100℃; The drying time is 8 to 24 hours.

9. A magnesium battery, characterized in that, Includes the sandwich-type sulfur-based positive electrode sheet according to any one of claims 1 to 5 or the sandwich-type sulfur-based positive electrode sheet prepared by the preparation method according to any one of claims 6 to 8.

10. The application of the sandwich-type sulfur-based positive electrode sheet according to any one of claims 1 to 5 or the sandwich-type sulfur-based positive electrode sheet prepared by the preparation method according to any one of claims 6 to 8 in metal sulfur-based batteries.

Images