Solid electrolyte membrane and solid-state battery

Abstract

The utility model provides a solid-state electrolyte membrane and a solid-state battery, and relates to the technical field of solid-state electrolyte membranes. The solid electrolyte membrane comprises an electrolyte sheet and a cobaltosic oxide layer attached to one surface of the electrolyte sheet. The cobaltosic oxide layer is arranged on the surface of the electrolyte sheet, and the cobaltosic oxide layer has relatively high surface flatness and uniform electric field distribution, so that the surface flatness of the electrolyte sheet can be effectively improved, the surface impedance of the electrolyte sheet can be effectively reduced, and the surface stability is improved; therefore, bad contact between the solid electrolyte membrane and the negative electrode can be effectively eliminated, electron and ion transmission is facilitated, interface side reactions (such as growth of lithium dendrites) can be inhibited, the surface impedance of an electrolyte sheet can be effectively reduced, the surface stability is improved, the polarization voltage of the solid-state battery is reduced, and the service life of the solid-state battery is prolonged. Therefore, the capacity and cycle performance of the solid-state battery are effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of solid electrolyte membranes, and in particular to a solid electrolyte membrane and a solid-state battery. Background Art

[0002] Solid-state electrolyte membranes are typically prepared by pressing solid electrolyte powders. This surface often exhibits numerous cracks and pores, resulting in poor surface flatness, high surface impedance, and poor surface stability. This results in insufficient contact between the solid electrolyte membrane and the electrode, compared to the effective contact between the liquid electrolyte and the electrode. This in turn leads to interfacial issues such as the formation of lithium dendrites, increased charge transfer impedance, and uneven current distribution. To optimize the surface properties of solid-state electrolyte membranes and address these interfacial issues, forming a protective coating on the surface of the solid-state electrolyte membrane is one of the most commonly used methods. For example, a LiF (or LiI) layer is formed on the surface of a sulfide solid-state electrolyte membrane, or a polyethylene oxide coating is formed on the surface of a garnet solid-state electrolyte membrane. However, these protective coatings currently provide limited improvement in the performance of solid-state electrolyte membranes. Utility Model Content

[0003] The present application is made in view of the above-mentioned problems, and its purpose is to provide a solid electrolyte membrane and a solid-state battery for improving the surface performance of the solid electrolyte membrane and thereby improving the interface problem between the solid electrolyte membrane and the negative electrode.

[0004] In a first aspect, an embodiment of the present application provides a solid electrolyte membrane, comprising an electrolyte sheet and a cobalt tetroxide layer attached to a surface of the electrolyte sheet.

[0005] In the above technical solution, by setting a cobalt tetroxide layer on the surface of the electrolyte sheet, the cobalt tetroxide layer has a high surface flatness and uniform electric field distribution, which can effectively improve the surface flatness of the electrolyte sheet. At the same time, it can also effectively reduce the surface impedance of the electrolyte sheet and improve the surface stability, thereby effectively eliminating the poor contact between the solid electrolyte membrane and the negative electrode, which is beneficial to the transmission of electrons and ions, and can inhibit interfacial side reactions (such as the growth of lithium dendrites). At the same time, it can also effectively reduce the surface impedance of the electrolyte sheet, improve the surface stability, and reduce the polarization voltage of the solid-state battery, thereby effectively improving the capacity and cycle performance of the solid-state battery.

[0006] In one possible implementation, the cobalt oxide layer includes cobalt oxide nanoparticles. Using cobalt oxide nanoparticles to form the cobalt oxide layer helps smooth the surface by filling microscopic cracks and pores on the surface of the electrolyte sheet, thereby helping to eliminate irregular defects on the surface of the electrolyte sheet and further improving the surface properties of the solid electrolyte membrane.

[0007] In one possible implementation, the average particle size of the cobalt oxide nanoparticles is 50 nm to 100 nm. By controlling the average particle size of the cobalt oxide nanoparticles within a suitable range, the cobalt oxide nanoparticles can effectively fill the microscopic cracks and pores on the surface of the electrolyte sheet, thereby making the surface of the electrolyte sheet smoother and further improving the surface properties of the solid electrolyte membrane.

[0008] In one possible implementation, the thickness of the cobalt oxide layer is 2μm to 4μm. By controlling the thickness of the cobalt oxide layer within an appropriate range, the solid electrolyte membrane has higher surface stability, which helps to form a good interface contact between the solid electrolyte membrane and the negative electrode, effectively relieves interfacial stress, inhibits interfacial side reactions (such as the growth of lithium dendrites), and improves interfacial stability, thereby further improving the capacity and cycle performance of the solid-state battery.

[0009] In one possible implementation, the surface density of the cobalt oxide layer is 0.0015 mg / mm 2 ~0.0030mg / mm 2 By controlling the surface density of the cobalt oxide layer within an appropriate range, the solid electrolyte membrane has higher surface flatness and surface stability, which can effectively isolate the solid electrolyte membrane and the negative electrode, fully inhibiting interfacial side reactions (such as the growth of lithium dendrites), thereby further improving the capacity and cycle performance of the solid-state battery.

[0010] In one possible implementation, the electrolyte sheet comprises an antiperovskite electrolyte, comprising one of Li3OX or Li2OHX, where X is Cl, F, Br, or I. Antiperovskite electrolytes have high ionic conductivity and are easy to prepare and process. However, these electrolyte sheets also have high interfacial resistance and poor interfacial compatibility with electrodes, which can easily induce electrochemical instability within the battery and reduce battery performance. Therefore, interfacial modification is necessary. By providing a cobalt oxide layer on the surface of the antiperovskite electrolyte sheet, the interfacial resistance can be effectively reduced, the interfacial compatibility with the electrodes can be improved, the stability of the solid-state battery can be enhanced, and the capacity and cycling performance of the solid-state battery can be improved.

[0011] In one possible implementation, the thickness of the electrolyte sheet is 0.5 mm to 1.5 mm. By controlling the thickness of the electrolyte sheet within a suitable range, it is beneficial to improve the ion transmission effect and maintain sufficient mechanical strength and stability.

[0012] In one possible implementation, the surface density of the electrolyte sheet is 1 mg / mm 2 ~1.5mg / mm 2 By controlling the surface density of the electrolyte sheet within an appropriate range, it is beneficial to further improve the ion transmission effect and enhance the interface stability.

[0013] In a second aspect, embodiments of the present application further provide a solid-state battery, comprising the solid-state electrolyte membrane provided in the first aspect of the embodiments of the present application. In one possible implementation, the solid-state battery further comprises a positive electrode sheet and a negative electrode sheet, the solid-state electrolyte membrane being disposed between the positive electrode sheet and the negative electrode sheet, and the cobalt oxide layer being in contact with the negative electrode sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] 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.

[0015] Figure 1 A schematic structural diagram of a solid electrolyte membrane provided in an embodiment of the present application.

[0016] Figure 2 A schematic structural diagram of a solid-state battery provided in an embodiment of the present application.

[0017] Figure 3 This is a scanning electron microscope (SEM) image of cobalt tetroxide provided in the examples of this application.

[0018] Figure 4 Scanning electron microscope (SEM) images of the surface of the electrolyte sheet and the surface of the solid electrolyte membrane provided in the embodiments of the present application.

[0019] Figure 5 Constant current charge and discharge test diagram of two symmetrical lithium batteries (Li|Li2OHCl|Li, Li|Co3O4|Li2OHCl|Co3O4|Li) provided for the test examples of this application.

[0020] Figure 6 Constant current discharge test curves of two lithium-copper batteries (Li|Li2OHCl|Cu, Li|Li2OHCl|Co3O4|Cu) provided for the test examples of this application.

[0021] Figure 7 Cyclic test curves of two all-solid-state batteries (Li|Li2OHCl|LFP, Li|Co3O4|Li2OHCl|LFP) provided for the test examples of this application.

[0022] Description of reference numerals:

[0023] 10-solid electrolyte membrane; 12-electrolyte sheet; 14-cobalt tetroxide layer; 20-positive electrode sheet; 30-negative electrode sheet; 100-solid-state battery. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0025] In the description of this utility model, it should be noted that the terms "upper," "lower," "inner," and "outer" and the like, when used to indicate orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the utility model product is typically placed when in use. These terms are intended solely to facilitate the description of this utility model and simplify the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and the like are used solely for distinction and should not be construed as indicating or implying relative importance.

[0026] Solid-state electrolyte membranes are typically prepared by pressing solid electrolyte powders. This surface often exhibits numerous cracks and pores, resulting in poor surface flatness, high surface impedance, and poor surface stability. This results in insufficient contact between the solid electrolyte membrane and the electrode, compared to the effective contact between the liquid electrolyte and the electrode. This in turn leads to interfacial problems such as the formation of lithium dendrites, increased charge transfer impedance, and uneven current distribution. To optimize the surface properties of solid-state electrolyte membranes and address these interfacial issues, forming a protective coating on the surface of the solid-state electrolyte membrane is one of the most commonly used methods. For example, a LiF (or LiI) layer is formed on the surface of a sulfide solid-state electrolyte membrane, or a polyethylene oxide coating is formed on the surface of a garnet solid-state electrolyte membrane. However, these protective coatings currently have limited effectiveness in improving the surface properties of solid-state electrolyte membranes.

[0027] Based on this, an embodiment of the present application provides a solid electrolyte membrane. Figure 1 This is a schematic diagram of the structure of a solid electrolyte membrane provided in the embodiment of the present application, see Figure 1 The solid electrolyte membrane 10 includes an electrolyte sheet 12 and a cobalt oxide layer 14 attached to one surface of the electrolyte sheet 12 .

[0028] In the embodiment of the present application, the "electrolyte sheet" can be obtained by pressing solid electrolyte particles. The pressing method can be cold pressing or hot pressing. The pressing method can be one-step pressing or step-by-step pressing. Affected by the unevenness of the particle size, insufficient pressure applied during the hot pressing process, etc., the surface of the electrolyte sheet is prone to irregular defects, such as microcracks and pores, resulting in poor surface flatness of the membrane, high surface impedance, and poor surface stability, which may adversely affect the ion conductivity of the electrolyte, become an obstacle to ion transport, and thus affect the overall electrochemical performance of the electrolyte sheet.

[0029] By forming a cobalt tetroxide layer on the surface of the electrolyte sheet, the cobalt tetroxide can partially fill the microscopic cracks and pores on the surface of the electrolyte sheet, achieving surface smoothing, helping to eliminate irregular defects on the surface of the electrolyte sheet and improve the surface flatness of the electrolyte sheet. At the same time, it can also effectively reduce the surface impedance of the electrolyte sheet and improve the surface stability, which can effectively solve the problem of insufficient interfacial contact between the solid electrolyte membrane and the electrode. Therefore, it is beneficial to promote the transmission of electrons and ions between the solid electrolyte membrane and the electrode, reduce the interfacial impedance (reducing the polarization voltage of the battery), and inhibit interfacial side reactions (such as the growth of lithium dendrites), thereby improving the capacity and cycle performance of the battery. In addition, the high mechanical strength of the cobalt tetroxide layer can effectively inhibit the penetration of lithium dendrites. At the same time, cobalt tetroxide has semiconductor properties, which can guide lithium ions to deposit uniformly on the negative electrode surface by homogenizing the interfacial electric field distribution, thereby delaying the loss of active lithium, which is beneficial to further improve the capacity and cycle performance of solid-state batteries.

[0030] In some embodiments, the cobalt oxide layer includes cobalt oxide nanoparticles. Cobalt oxide nanoparticles are nanometer-sized particles that can effectively fill microscopic cracks and pores on the surface of the electrolyte sheet and form a uniform and smooth surface.

[0031] Furthermore, the average particle size of the cobalt oxide nanoparticles is 50 nm to 100 nm. For example, the average particle size of the cobalt oxide nanoparticles is 50 nm, 80 nm, 100 nm, etc.

[0032] In some embodiments, the thickness of the cobalt oxide layer is 2 μm to 4 μm. For example, the thickness of the cobalt oxide layer is 2 μm, 3 μm, 4 μm, etc.

[0033] In some embodiments, the surface density of the cobalt oxide layer is 0.0015 mg / mm 2 ~0.0030mg / mm 2 As an example, the surface density of the cobalt oxide layer is 0.0015 mg / mm 2 , 0.0020mg / mm 2, 0.0025mg / mm 2 , 0.0030mg / mm 2 wait.

[0034] In the embodiments of the present application, "area density" refers to the mass of the interface layer per unit area. A suitable areal density of the cobalt oxide layer is beneficial for further improving ion transmission, reducing interface impedance, and enhancing interface stability.

[0035] In some embodiments, the material of the electrolyte sheet includes an antiperovskite electrolyte, and the antiperovskite electrolyte includes one of Li3OX or Li2OHX, wherein X is Cl, F, Br, or I. As an example, the material of the electrolyte sheet is Li3OCl, Li2OHCl, etc.

[0036] In the embodiments of this application, an "antiperovskite electrolyte" is a novel electrolyte structure formed by electrically reversing the cations and anions in a traditional perovskite structure. In other words, an antiperovskite electrolyte has the same topological structure as a perovskite electrolyte, but with a reversed ionic arrangement. This means that compared to the traditional perovskite cation center unit, an antiperovskite electrolyte has a unique anion center unit, typically exhibiting a lower melting point, better stability to metallic lithium, and higher ionic conductivity. These can be prepared using high-temperature solid-phase methods or solution methods (such as sol-gel methods and coprecipitation methods).

[0037] Antiperovskite electrolytes, a new class of solid-state electrolytes, possess superior electrochemical properties compared to traditional solid-state electrolytes (such as sulfide and garnet-type solid-state electrolytes), particularly low melting points and improved stability toward metallic lithium. Consequently, they have attracted considerable research attention. However, antiperovskite electrolytes exhibit high interfacial resistance and poor interfacial compatibility with electrodes, which can easily induce electrochemical instability within the battery and reduce battery performance. This has hindered the practical application of antiperovskite electrolytes. Furthermore, research on antiperovskite electrolytes is still in its infancy, and understanding of their interfacial stability in full battery systems is insufficient.

[0038] This application provides a cobalt tetroxide layer on the surface of the antiperovskite electrolyte sheet, which can effectively reduce the interface resistance, improve the interface compatibility with the negative electrode, improve the stability of the solid-state battery, and thus improve the capacity and cycle performance of the solid-state battery.

[0039] In some embodiments, the thickness of the electrolyte sheet is 0.5 mm to 1.5 mm. For example, the thickness of the electrolyte sheet is 0.5 mm, 1.0 mm, 1.2 mm, 1.5 mm, etc.

[0040] In some embodiments, the surface density of the electrolyte sheet is 1 mg / mm2 ~1.5mg / mm 2 The surface density of the electrolyte sheet is 1 mg / mm 2 , 1.1mg / mm 2 , 1.2mg / mm 2 , 1.5mg / mm 2 wait.

[0041] In a second aspect, an embodiment of the present application further provides a solid-state battery, comprising the solid-state electrolyte membrane provided in the first aspect of the embodiment of the present application.

[0042] Figure 2 For a structural diagram of a solid-state battery provided in an embodiment of the present application, see Figure 2 The solid-state battery 100 includes a solid electrolyte membrane 10, and a positive electrode sheet 20 and a negative electrode sheet 30 disposed on opposite sides of the solid electrolyte membrane 10. The cobalt oxide layer 14 is disposed between the negative electrode sheet 30 and the electrolyte sheet 12, i.e., the cobalt oxide layer 14 is in contact with the negative electrode sheet 30. In the embodiments of the present application, the positive electrode sheet and the negative electrode sheet are not specifically limited. Positive electrode sheets and negative electrode sheets commonly used in solid-state batteries in the art can be used.

[0043] In some embodiments, the positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer attached to the surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.

[0044] In some embodiments, the specific type of positive electrode active material is not particularly limited. As an example, the positive electrode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and modified compounds thereof. However, this application is not limited to these materials; other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more.

[0045] In some embodiments, there is no particular limitation on the specific type of the positive electrode current collector. The positive electrode current collector can be a conductive carbon sheet, a metal foil, a carbon-coated metal foil, a porous metal plate, or a composite current collector. The conductive carbon material of the conductive carbon sheet can be selected from one or more of conductive carbon black (Super P), carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers. The metal material of the metal foil, the carbon-coated metal foil, and the porous metal plate can be independently selected from at least one of copper, aluminum, nickel, and stainless steel. The composite current collector can be a composite current collector formed by combining a metal foil and a polymer base film.

[0046] In some embodiments, the positive electrode film layer may optionally include a binder. For example, the binder includes at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorinated acrylate resin.

[0047] In some embodiments, the positive electrode film layer may further include a conductive agent. For example, the conductive agent may be selected from at least one of conductive carbon black (Super P), acetylene black, vapor-grown carbon fiber (VGCF), carbon nanotubes, and graphene.

[0048] The preparation method of the positive electrode sheet may include: dispersing the components used to prepare the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode collector, and obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0049] In some embodiments, the negative electrode plate includes a negative electrode current collector and a metallic lithium or lithium alloy layer disposed on the negative electrode current collector. The lithium alloy may include at least one of a lithium-indium alloy, a lithium-zinc alloy, a lithium-magnesium alloy, a lithium-tin alloy, and a lithium-silver alloy. The metallic lithium or lithium alloy layer may have a thickness of 1 μm to 200 μm, preferably 5 μm to 100 μm.

[0050] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (sodium, sodium alloys, copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, silver alloys, etc.) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0051] In some embodiments, the negative electrode sheet may be prepared by attaching metallic lithium or lithium alloy to the surface of the negative electrode current collector to form the negative electrode sheet.

[0052] In some embodiments, the preparation method of a solid-state battery may include: stacking (and winding) the positive electrode sheet, the solid electrolyte membrane, and the negative electrode sheet in sequence, pressurizing and compounding them together at a certain temperature to obtain a battery cell, placing the battery cell in a shell, and encapsulating it to obtain a solid-state battery.

[0053] Example

[0054] 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.

[0055] Example 1

[0056] This embodiment provides a solid electrolyte membrane, the preparation method of which includes the following steps:

[0057] (1) Preparation of electrolyte sheets

[0058] The Li2OHCl solid electrolyte was fully ground in an agate mortar for 30 minutes to obtain Li2OHCl powder. The Li2OHCl powder was hot-pressed at 150°C for 30 minutes under a pressure of 10 MPa to form a 10 mm diameter disc-shaped electrolyte. Each disc weighed about 0.08 g, was 0.8 mm thick, and had an area density of 1 mg / mm. 2 .

[0059] (2) Preparation of cobalt tetroxide layer

[0060] In an argon glove box, 2 mg of cobalt tetroxide powder was evenly coated on one side of the electrolyte sheet using a dust-free cotton swab until the electrolyte surface changed from its original white to a uniform brown color, forming a cobalt tetroxide layer. This resulted in a solid electrolyte membrane with a thickness of 2 μm and an area density of 0.0015 mg / mm2. 2 .

[0061] The cobalt oxide powder, electrolyte sheet and solid electrolyte membrane were analyzed by scanning electron microscope.

[0062] Figure 3 This is a scanning electron microscope (SEM) image of cobalt tetroxide provided in the examples of the present application, wherein: Figure 3 (b) is correct Figure 3 A partial enlarged view of (a). Figure 3 It can be seen from the figure that the cobalt trioxide powder is cobalt trioxide nanoparticles, and the average particle size is about 100 nm.

[0063] Figure 4 This is a scanning electron microscope (SEM) image of the surface of the electrolyte sheet and the solid electrolyte membrane provided in Example 1 of the present application. Figure 4 (a) is the SEM image of the electrolyte sheet surface. Figure 4 (b) is correct Figure 4 A partial enlarged view of (a); Figure 4 (c) is the SEM image of the solid electrolyte membrane surface. Figure 4 (d) is correct Figure 4 (c) is a SEM image of a local magnified view. Figure 4 As can be seen from (a) and (b) in the figure, there are many micro cracks and pores on the surface of the unmodified electrolyte sheet, and the surface is not smooth. Figure 4 As can be seen from (c) and (d), after the cobalt oxide layer is set, the surface of the solid electrolyte membrane is relatively flat and smooth, indicating that the cobalt oxide layer effectively fills the micro cracks and pores on the surface of the electrolyte sheet, achieving surface smoothing.

[0064] Test example

[0065] (1) Symmetrical battery cycling stability

[0066] Cobalt tetroxide was coated on opposite sides of the electrolyte sheet prepared in Example 1 to form a cobalt tetroxide layer, resulting in a solid electrolyte membrane. This membrane was then combined with two lithium metal electrodes to create a symmetrical lithium battery, designated Li|Co3O4|Li2OHCl|Co3O4|Li. A symmetrical lithium battery, designated Li|Li2OHCl|Li, was also prepared using an uncoated electrolyte sheet as a control. Constant current charge and discharge tests were performed on the two symmetrical lithium batteries, Li|Li2OHCl|Li and Li|Co3O4|Li2OHCl|Co3O4|Li, at 130°C. The current density was set at 0.1 mA / cm², with a 30-minute charge and 30-minute discharge cycle. Long-term cycling testing was performed until the batteries exhibited abnormalities.

[0067] Figure 5 The constant current charge and discharge test diagram of two symmetrical lithium batteries (Li|Li2OHCl|Li, Li|Co3O4|Li2OHCl|Co3O4|Li) provided in the test example of this application is Figure 5 It can be seen that the symmetric lithium battery without a cobalt oxide layer (Li|Li2OHCl|Li) short-circuited at 506 hours, indicating that lithium dendrites appeared in the battery and penetrated the electrolyte, leading to battery failure. The battery with a cobalt oxide layer (Li|Co3O4|Li2OHCl|Co3O4|Li) had a cycle life extended to 566 hours, and the battery short-circuit failure time was delayed, indicating that the cobalt oxide layer suppressed the growth of lithium dendrites.

[0068] From the above, it can be seen that the cobalt oxide layer can effectively inhibit the formation and penetration of lithium dendrites through its high mechanical strength and uniform electric field distribution, thereby extending the battery life and significantly improving the cycle stability of the Li2OHCl solid electrolyte.

[0069] (2) Lithium-copper (Li-Cu) battery performance test

[0070] Li-Cu batteries were assembled using lithium (6mm diameter) as the negative electrode and copper (8mm diameter) as the positive electrode. An unmodified antiperovskite (Li2OHCl) solid electrolyte membrane and a Li2OHCl solid electrolyte membrane with a cobalt tetroxide layer were used. In Li-Cu battery research, surface modification is performed specifically on the side of the solid electrolyte membrane closest to the Cu positive electrode, where the cobalt tetroxide layer is applied. Therefore, the unmodified Li-Cu battery is designated as Li|Li2OHCl|Cu, while the modified Li-Cu battery is designated as Li|Li2OHCl|Co3O4|Cu. Constant current discharge tests were conducted on both lithium-copper batteries at a current density of 0.1 mA / cm².

[0071] Figure 6 The constant current discharge test curves of two lithium-copper batteries (Li|Li2OHCl|Cu, Li|Li2OHCl|Co3O4|Cu) provided in the test example of this application are shown in FIG. Figure 6 As can be seen in the figure, the Li|Li2OHCl|Co3O4|Cu battery exhibits a certain degree of capacity release during the initial discharge period. This observation is likely related to the chemical reaction between the solid electrolyte and the cobalt oxide layer on the copper surface during lithium ion deposition onto the copper cathode, potentially forming an intermediate layer. The Li|Li2OHCl|Cu battery exhibits a short short-circuit time (approximately 0.3 h) during discharge, indicating uneven lithium ion deposition on the copper cathode surface, forming lithium dendrites. These dendrites not only hinder lithium ion transport but can also cause electrolyte penetration, leading to battery short circuits. The Li|Li2OHCl|Co3O4|Cu battery exhibits a significantly prolonged short-circuit time (approximately 2.0 h), indicating that the cobalt oxide layer, through its high mechanical strength and uniform electric field distribution, effectively suppresses lithium dendrite formation, allowing lithium ion deposition on the copper electrode surface to be more uniform.

[0072] In addition, from the perspective of polarization voltage, the Li|Li2OHCl|Cu battery has a maximum polarization voltage of 0.13V, and the polarization voltage of the Li|Li2OHCl|Co3O4|Cu battery drops slightly to 0.06V.

[0073] From the above, it can be seen that by setting up a cobalt tetroxide layer, the short-circuit time of the lithium-copper battery is significantly prolonged, and the lithium ions are deposited more evenly on the surface of the copper positive electrode.

[0074] (3) All-solid-state battery testing

[0075] An all-solid-state battery was assembled using lithium as the anode and lithium iron phosphate (LFP) as the cathode. Two types of Li₂OHCl solid electrolytes were used: one without surface modification and one with a cobalt tetroxide layer, with the cobalt tetroxide coating applied to the side closest to the lithium anode. The battery without the protective layer is designated Li|Li₂OHCl|LFP, while the battery with the cobalt tetroxide layer is designated Li|Co₃O₄|Li₂OHCl|LFP. Testing conditions were a 0.1C rate and a temperature of 130°C.

[0076] Figure 7 The cycle test curves of two all-solid-state batteries (Li|Li2OHCl|LFP, Li|Co3O4|Li2OHCl|LFP) provided for the test examples of this application are as follows: Figure 7 It can be seen that the Li|Li2OHCl|LFP battery exhibits a lower discharge capacity (only 38.6 mAh / g) in the 90th cycle, while the Li|Co3O4|Li2OHCl|LFP battery exhibits a higher discharge capacity (93.2 mAh / g) in the 90th cycle.

[0077] As can be seen above, the difference in cycle capacity of all-solid-state batteries is essentially due to the synergistic optimization of the cobalt oxide layer in suppressing interfacial side reactions and lithium-ion transport kinetics. The high mechanical modulus of the cobalt oxide layer effectively inhibits the vertical penetration of lithium dendrites. At the same time, its semiconductor properties homogenize the interfacial electric field distribution, guiding the uniform deposition of lithium ions on the negative electrode surface, thereby delaying the loss of active lithium.

[0078] 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 solid electrolyte membrane, characterized in that The invention comprises an electrolyte sheet and a cobalt trioxide layer attached to a surface of the electrolyte sheet.

2. The solid electrolyte membrane according to claim 1, characterized in that The cobalt tetroxide layer includes cobalt tetroxide nanoparticles.

3. The solid electrolyte membrane according to claim 2, characterized in that The average particle size of the cobalt trioxide nanoparticles is 50nm-100nm.

4. The solid electrolyte membrane according to claim 1, wherein The thickness of the cobalt trioxide layer is 2 μm to 4 μm.

5. The solid electrolyte membrane according to claim 1, wherein The surface density of the cobalt oxide layer is 0.0015 mg / mm 2 ~0.0030mg / mm 2 .

6. The solid electrolyte membrane according to claim 1, characterized in that The material of the electrolyte sheet includes an antiperovskite electrolyte, and the antiperovskite electrolyte includes one of Li3OX or Li2OHX; wherein X is Cl, F, Br or I.

7. The solid electrolyte membrane according to claim 1, characterized in that The thickness of the electrolyte sheet is 0.5 mm to 1.5 mm.

8. The solid electrolyte membrane according to claim 1, characterized in that The surface density of the electrolyte sheet is 1 mg / mm 2 ~1.5mg / mm 2 .

9. A solid-state battery, characterized in that: The invention comprises the solid electrolyte membrane according to any one of claims 1 to 8.

10. The solid-state battery according to claim 9, characterized in that The solid-state battery further includes a positive electrode sheet and a negative electrode sheet, the solid electrolyte membrane is arranged between the positive electrode sheet and the negative electrode sheet, and the cobalt oxide layer is in contact with the negative electrode sheet.

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