Method for tracing migration path of migrating ions in solid-state battery

Abstract

A method for tracing the migration path of migrating ions in a solid-state battery. The method comprises the following steps: (1) adding an ion donor material to a solid-state battery, and then subjecting the solid-state battery to a charge and discharge cycle, wherein the solid-state battery comprises migrating ions, the ion donor material is used for providing exogenous ions, the exogenous ions and the migrating ions have the same valence state and similar ion radii, and the atomic number of the exogenous ions is higher than that of the migrating ions; and (2) subjecting the solid-state battery which has completed a charge and discharge cycle to characterization analysis, so as to determine the migration path of the exogenous ions, and using the migration path as the migration path of the migrating ions in the solid-state battery. By means of using the tracing method, the migration path of migrating ions in a solid-state battery, especially in a positive electrode and a solid electrolyte of the solid-state battery, can be graphically characterized.

Description

Methods for tracing the migration paths of migrating ions in solid-state batteries Technical Field

[0001] This invention belongs to the field of energy storage technology. Specifically, this invention relates to a method for tracing the migration paths of migrating ions in solid-state batteries. Background Technology

[0002] Solid-state batteries, as a novel energy storage technology, hold promise for meeting the application requirements of high energy density and long lifespan, and are expected to become a candidate for next-generation energy storage technology. The performance of solid-state batteries is closely related to the formation and evolution of ion transport pathways within them.

[0003] Characterizing and understanding ion pathways in solid-state batteries plays a crucial role in several aspects: for the positive electrode, it allows for failure characterization and optimization of the positive electrode design; for the electrolyte, it enables understanding of ion transport pathways, guiding the design of electrolytes with superior performance; and for the negative electrode, it allows for optimization of uniform ion deposition. However, current methods for characterizing ion pathways in solid-state batteries are insufficient to meet the development needs of solid-state batteries, facing severe limitations in scale and applicability. For example, nuclear magnetic resonance spectroscopy can obtain ion diffusion information at the nanoscale to submicron scale, and transmission electron microscopy-electron energy loss spectroscopy can obtain ion distribution information at interfaces smaller than 1 micrometer, but existing methods struggle to effectively characterize the ion pathways throughout the entire solid-state battery.

[0004] CN 111504914A discloses an in-situ testing device for solid-state batteries, which allows observation of structural changes in the solid electrolyte and the interface between the electrode material and the solid electrolyte through an observation window. This enables spectroscopic structural characterization of the electrode material and the solid electrolyte interface of the solid-state battery at different ambient temperatures. Although optical observation and spectroscopic structural characterization can be performed during solid-state battery cycling, spectroscopic characterization cannot obtain relevant information about ion pathways within the solid-state battery.

[0005] Since the ions migrating in solid-state batteries are mostly light element ions such as lithium and sodium, the current industry has limited methods for characterizing ion pathways in solid-state batteries, especially the ion pathways in the cathode and electrolyte of solid-state batteries are difficult to characterize effectively.

[0006] Therefore, there is an urgent need to develop a method for tracing ion pathways in solid-state batteries, which can effectively characterize ion migration pathways in solid-state batteries under electric field-driven conditions during cycling.

[0007] Invention Overview

[0008] The purpose of this invention is to provide a method for tracing the migration paths of ions in solid-state batteries. This method utilizes the movement mechanism of metal ions in a solid electrolyte. During cycling, exogenous ions provided by an ion donor material migrate, leaving clear migration paths in the solid-state battery. By observing the paths of these exogenous ions, the migration paths of ions in the solid-state battery can be traced, thereby effectively characterizing the migration paths of ions in the solid-state battery.

[0009] The above-mentioned objective of the present invention is achieved through the following technical solution.

[0010] In the context of this invention, the term "solid-state battery" can refer to any of the following: hybrid solid-liquid battery, semi-solid-state battery, quasi-solid-state battery, all-solid-state battery, or any of the following: solid-state lithium battery, solid-state sodium battery, or solid-state alkali metal battery, but is not limited thereto.

[0011] In the context of this invention, the term "ion donor material" refers to a material that, under an applied electric field, can directly release exogenous ions whose valence state is consistent with and has a similar radius to the original migrating ions in the solid-state battery, but which are different from the original migrating ions in the solid-state battery; or, during cycling, after the ion donor material is oxidized or reduced under an applied voltage, under an applied electric field, it can release exogenous ions whose valence state is consistent with and has a similar radius to the original migrating ions in the solid-state battery, but which are different from the original migrating ions in the solid-state battery.

[0012] In the context of this invention, the term "exogenous ions" does not refer to migrating metal ions in a solid-state battery, but rather to ions provided by an ion donor material under an applied electric field.

[0013] In the context of this invention, the term "window size" refers to the coverage area of ​​exogenous ions provided by the ion donor material within the solid-state battery. A larger window indicates a greater degree of coverage of the various components of the solid-state battery (including the positive electrode, electrolyte, and negative electrode), i.e., a larger area that can be traced and observed.

[0014] In the context of this invention, the term "resolution" refers to the minimum resolution of the ion paths left by exogenous ions in a solid-state battery during subsequent characterization (such as SEM-EDS). A smaller resolution indicates a stronger ability to distinguish ion paths in different components of the solid-state battery.

[0015] In the context of this invention, the term "ion path depth" refers to the depth to which exogenous ions migrate within a solid-state battery under certain conditions. A greater depth indicates a stronger migration ability of exogenous ions within the solid-state battery under those conditions, and a larger viewing window.

[0016] In the context of this invention, the term "lithium-ion enrichment" refers to the percentage of lithium-ion atoms within a specific region of a solid-state battery. By comparing lithium-ion enrichment levels, information on lithium-ion migration or blockage can be obtained.

[0017] This invention provides a method for tracing the migration paths of migrating ions in a solid-state battery, comprising the following steps:

[0018] (1) Add an ion donor material to a solid-state battery and then charge and discharge the solid-state battery; wherein the solid-state battery contains migrating ions, the ion donor material is used to provide exogenous ions, the exogenous ions have the same valence state and similar ionic radius as the migrating ions, and the atomic number is higher than that of the migrating ions;

[0019] (2) The solid-state battery that has completed the charge-discharge cycle is characterized and analyzed to determine the migration path of the exogenous ions and to use it as the migration path of the migrating ions in the solid-state battery.

[0020] Preferably, in the method described in this invention, the difference in ionic radius between the migrating ion and the exogenous ion is less than or equal to 50 pm.

[0021] Preferably, in the method described in this invention, the difference in ionic radius between the migrating ion and the exogenous ion is less than or equal to 20 pm.

[0022] In this invention, "similar ionic radii" means that the difference between the radii of two ions is less than or equal to 50 pm (picometers). Specifically, the difference in ionic radii includes, but is not limited to, values ​​less than or equal to: 50 pm, 20 pm, 18 pm, 15 pm, 10 pm, 8 pm, 5 pm, 3 pm, 2 pm, and 1 pm. "The original migrating ion and the exogenous ion have the same valence state" means that they are both +1 or both +2, as long as the valence state is the same, but it is not limited to these.

[0023] Preferably, in the method described in this invention, the ion donor material is selected from one or more of a first subgroup element and / or a compound containing a first subgroup element.

[0024] Preferably, in the method described in this invention, the first subgroup element is copper and / or silver.

[0025] Preferably, in the method described in this invention, the ion donor material is selected from one or more of elemental copper, copper nitride, copper oxide, cuprous oxide, copper fluoride, copper phosphide, cuprous phosphide, copper sulfide, cuprous sulfide, copper chloride, cuprous chloride, copper sulfate, copper selenide, cuprous selenide, cuprous iodide, elemental silver, silver oxide, silver fluoride, silver sulfide, silver chloride, silver arsenide, silver selenide, silver bromide, and silver iodide.

[0026] Preferably, in the method described in this invention, the exogenous ions are copper ions and / or silver ions.

[0027] Preferably, in the method described in this invention, the exogenous ion is selected from Cu. + Cu 2+ and Ag + One or more of them.

[0028] Preferably, in the method of the present invention, the solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte, wherein the positive electrode comprises a positive electrode material, and the addition of the ion donor material to the solid-state battery in step (1) is performed by a method including the following steps:

[0029] Implanting ion donor materials on the surface of a solid electrolyte; and / or

[0030] Implanting ion donor materials on the surface of the positive electrode of a solid-state battery; and / or

[0031] Ion donor materials are added to the cathode material of solid-state batteries.

[0032] Preferably, in the method described in this invention, the solid-state battery is selected from one or more of hybrid solid-liquid batteries, quasi-solid-state batteries, and all-solid-state batteries.

[0033] Preferably, in the method described in this invention, the solid-state battery is a solid-state lithium battery and / or a solid-state sodium battery.

[0034] Preferably, in the method described in this invention, the characterization analysis includes one or more of SEM-EDS (scanning electron microscope-energy dispersive X-ray spectroscopy), SIMS (secondary ion mass spectrometry), XPS (X-ray photoelectron spectroscopy), CT (computed tomography), and Auger electron spectroscopy.

[0035] The tracing method of the present invention can be used for solid-state battery failure analysis and / or solid electrolyte composition analysis and / or solid-state battery system design.

[0036] This invention provides a method for tracing ion pathways in solid-state batteries. By introducing specific ion donor materials into the solid-state battery, the migration pathways of exogenous ions provided by the ion donor materials are used to characterize the migration ion pathways in the active materials of the solid-state battery. This is because the migrating ions in the solid-state battery (alkali metal ions, such as Li) + and Na +Solid-state batteries (SSBs) have low atomic numbers, making characterization difficult. Existing detection techniques cannot provide graphical, full-scale characterization of ion pathways. For example, transmission electron microscopy combined with energy loss spectroscopy (TEM-EELS), commonly used for ion pathway resolution, can only characterize lithium enrichment at material or electrode interfaces due to its small viewing window, failing to meet the characterization requirements of ion pathways throughout the entire battery. Furthermore, existing technologies cannot visualize ion movement paths due to the inability to label ions. Therefore, this invention introduces specific ion donor materials into solid-state batteries. During cycling, the metal ions obtained after the exogenous ions directly provided by the ion donor material are oxidized or reduced, interact with migrating ions (e.g., Li) in the solid-state battery. + and Na + Because ions have similar radii and valence states, they share the same migration paths and similar migration capabilities. Furthermore, since exogenous ions have a significantly increased number of charged nuclei, they can be detected by conventional characterization methods. The observation of these exogenous tracer metal ions can cover the entire battery system, meaning that tracer ions can be observed in the positive electrode, electrolyte, and negative electrode of a solid-state battery. By using exogenous ion tracers instead of observing the original migrating ions in the solid-state battery, the limitation of incomplete observation due to low atomic numbers can be avoided. Therefore, the exogenous ion tracer method of this invention can obtain the ion paths throughout the entire battery.

[0037] The tracer method of this invention enables graphical characterization of ion pathways in solid-state batteries, particularly in the cathode and solid electrolyte. This is because while nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics simulations (MD) can obtain information on lithium-ion diffusion at the nanoscale, they cannot obtain spatial location information of lithium ions. Transmission electron microscopy-electron energy loss spectroscopy (TEM-EELS) can obtain transport information of ions at the bulk phase and / or interface at a scale of 1 μm or less, but due to the limitations of the imaging window of TEM, it cannot obtain transport and location information of lithium ions at a scale greater than 1 μm. This invention employs a method of introducing exogenous ions, which are perfectly suited for integration with conventional microscopic characterization techniques such as SEM-EDS. Within the imaging scale covered by SEM-EDS (10 nm-1 mm), the ion transport pathways in all components of the solid-state battery can be characterized. This imaging scale covers a range from microscopic (e.g., the observation of ion pathways at grain boundaries in solid electrolytes, where grain boundary striations are approximately tens to hundreds of nanometers) to macroscopic (e.g., the observation of ion pathways throughout the entire battery, where the distribution of ion pathways at the battery scale is from hundreds of micrometers to several millimeters). Precise observation of ion pathways helps guide the design of solid electrolytes, analyze the construction and failure mechanisms of ion pathways in the cathode of solid-state batteries, optimize solid-state battery systems, and ultimately promote the large-scale application of solid-state batteries.

[0038] The applicant discovered that in solid-state batteries, if the exogenous ions have a similar ionic radius and the same valence state as the existing migrating ions in the solid-state battery, for example, in solid-state lithium batteries, the exogenous ion Cu... + (77pm) and Li + (76 pm) Ion radii differ by 1 pm, exogenous ion Ag + (115pm) and Li + The ionic radii differ by 39 pm (76 pm); for solid-state sodium batteries, the exogenous ion Ag... + (115pm) and Na + The ionic radii differ by 13 pm (102 pm), indicating that the exogenous Cu ion... + (77pm) and Na + The ionic radii differ by 25 pm (102 pm), and the exogenous ion Au... + (137pm) and Na + The ionic radii differ by 35 pm (102 pm). Even with the difference in the number of charged nuclei, exogenous ions in solid-state batteries still possess the same migration path and similar migration ability as the original migrating ions, and adding an appropriate amount of exogenous ions does not affect the original performance of the battery. This is because exogenous ions and the original migrating ions in solid-state batteries have similar electron cloud morphologies, resulting in similar coordination effects between exogenous and migrating ions in the material. Thus, exogenous ions can mimic some characteristics of migrating ions in terms of physical and electrochemical properties, and therefore can replace migrating ions in moving within solid-state batteries. By limiting the ionic valence state and ionic radius, the electric field of exogenous ions is made similar to that of migrating ions, ensuring that the electric driving force experienced by exogenous ions in the material lattice is the same, thereby making the migration path and migration ability of the original migrating ions and exogenous ions essentially the same during charging and discharging. However, exogenous ions have a higher number of charged nuclei than the original migrating ions, making them more sensitive to imaging under conventional characterization methods (such as SEM-EDS and CT) and easier to graphically characterize. In contrast, the original migrating ions in solid-state batteries, such as Li... + Because its atomic number is too small, it is not visible to conventional characterization methods.

[0039] Based on the above characteristics, the aforementioned exogenous ions can replace the original migrating ions in the solid-state battery, migrating within the battery during charge and discharge. Because they differ from the original migrating ions, they leave migration paths after migration, which can be identified by conventional characterization and analysis methods. Furthermore, in the method of this invention, exogenous ions can migrate in the positive, electrolyte, and negative electrodes of the solid-state battery, covering the entire battery. Current characterization methods (such as EDS and CT) can cover the imaging scale of solid-state batteries from the microscopic to the device scale (10 nm-1 mm). Therefore, the method of this invention can visualize the ion migration paths throughout the solid-state battery. By adding the ion donor material of this invention to the solid-state battery, the migration paths of exogenous ions in the solid-state battery can be observed after cycling. By observing the exogenous ion paths, ion path tracing from the microscopic to the device scale (10 nm-1 mm) throughout the solid-state battery can be achieved. In contrast, TEM-EELS can only observe the enrichment degree of migrating ions within a window smaller than 1 μm, and NMR cannot obtain the spatial location information of migrating ions, thus failing to meet the ion path imaging requirements of the entire solid-state battery as the method of this invention does. Because this invention uses an exogenous ion tracer, it is applicable to conventional detection methods and techniques such as EDS and CT.

[0040] The present invention has the following beneficial effects:

[0041] The tracer method of the present invention enables graphical characterization of the migration paths of migrating ions in solid-state batteries, especially in the cathode and solid electrolyte of solid-state batteries.

[0042] The exogenous ions introduced in this invention are perfectly suited for integration with conventional microscopic characterization techniques such as SEM-EDS. Within the imaging scale covered by SEM-EDS (10 nm-1 mm), the ion transport pathways in all components of the entire solid-state battery can be characterized. This imaging scale covers a range from microscopic (e.g., the observation of ion pathways at grain boundaries in solid electrolytes, where grain boundary striations are approximately tens to hundreds of nanometers) to macroscopic (e.g., the observation of ion pathways throughout the entire battery, where the distribution of ion pathways at the battery scale is from hundreds of micrometers to several millimeters).

[0043] Precise observation of ion pathways helps guide the design of solid electrolytes, analyze the construction and failure mechanisms of ion pathways in the cathode of solid-state batteries, optimize the solid-state battery system, and thus promote the large-scale application of solid-state batteries.

[0044] Brief description of the attached figures

[0045] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:

[0046] Figure 1 is a schematic diagram of a specific embodiment of the present invention; wherein, the left figure is a schematic diagram of the initial position of the copper foil of battery number a2 in embodiment 1 of the present invention and the copper ion path in the positive electrode after cycling, and the right figure is a schematic diagram of the characterization of the degree of lithium ion enrichment at the interface between the positive electrode and the electrolyte of the solid battery by the TEM-EELS method.

[0047] Figure 2A is a scanning electron microscope image of the positive electrode and surface copper powder of battery a3 in Embodiment 1 of the present invention when it is not cycled;

[0048] Figure 2B is the EDS energy spectrum of copper element in the positive electrode and surface copper powder of battery a3 in Example 1 of the present invention when it is not cycled.

[0049] Figure 3A is a low-magnification scanning electron microscope image of the positive electrode of battery a3 after cycling in Embodiment 1 of the present invention.

[0050] Figure 3B is the EDS energy spectrum of copper in the positive electrode of battery a3 after cycling in Embodiment 1 of the present invention.

[0051] Figure 3C is a high-magnification scanning electron microscope image of the selected area shown in the white box in Figure 3A after cycling of battery number a3 in Embodiment 1 of the present invention; the figure shows the morphology of the ion pathway in the electrolyte;

[0052] Figure 3D is the EDS energy spectrum of the ion pathway in Figure 3C after cycling of battery number a3 in Embodiment 1 of the present invention;

[0053] Figure 4 is a SEM-EDS energy spectrum of the ion pathway in the electrolyte of battery b2 after cycling in Example 2 of the present invention.

[0054] Figure 5 is a SEM-EDS energy spectrum of the ion pathway in the electrolyte of battery c1 in Example 3 of the present invention after one charge.

[0055] Figure 6 is a SEM-EDS energy spectrum of the ion pathway in the positive electrode of battery d8 in Example 4 of the present invention.

[0056] Figure 7 is a photograph of the lithium metal anode and polymer electrolyte after disassembly of battery number e2 in Embodiment 5 of the present invention.

[0057] Figure 8 shows the SEM-EDS energy dispersive spectroscopy of the ion pathways in the positive electrode and electrolyte of battery g3 in Example 7 of the present invention.

[0058] The best way to implement an invention

[0059] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0060] Example 1

[0061] The ion pathway corresponds to a window size that can cover the entire scale of solid-state batteries.

[0062] This embodiment uses LiNi 0.8 Co 0.1 Mn 0.1 O2 is used as the positive electrode active material, Li6PS5Cl is used as the solid electrolyte, and lithium metal is used as the negative electrode. Copper foil, copper powder, Cu2S, CuI, CuCl, Ag2S, AgCl, and AgBr are used as ion donor materials. These ion donor materials are uniformly coated on the surface of the solid positive electrode to assemble the solid battery. The solid battery positive electrode material is then characterized after cycling.

[0063] By introducing ion donor materials, the effects of metal element ions (with Cu) on the evolution of metal element ions (in the form of Cu) can be elucidated. + and Ag + For example, ion paths can migrate within a solid-state battery and leave a migration path after migration. It is observed that the window size corresponding to the ion path can cover the entire scale of the solid-state battery, thereby achieving coverage of ion paths in each component (positive electrode, electrolyte, and negative electrode) of the solid-state battery.

[0064] The solid-state battery manufacturing process is as follows:

[0065] 1. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Then, add LiNi... 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was weighed and placed on one side of the electrolyte sheet, and kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium foil was cut into a 9.5 mm diameter disc and placed on the other side of the electrolyte sheet, and kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as a1.

[0066] 2. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Then, add LiNi... 0.8 Co 0.1 Mn 0.1O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. A 10 mg / mm diameter copper foil was placed on the surface of the composite positive electrode and kept under a pressure of 360 MPa for 10 min. A 9.5 mm diameter circular piece of 50 μm thick lithium foil was cut and placed on the other side of the electrolyte sheet and kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as a2.

[0067] 3. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Then, add LiNi... 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. 10 mg of elemental copper powder was then evenly placed on the surface of the composite positive electrode and kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium foil was cut into a 9.5 mm diameter disc and placed on the other side of the electrolyte sheet. The mixture was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as a3.

[0068] 4. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Add LiNi... 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. 10 mg of Cu2S was then evenly placed on the surface of the composite positive electrode and kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into a 9.5 mm diameter disc and placed on the other side of the electrolyte sheet. The disc was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as a4.

[0069] 5. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Add LiNi... 0.8 Co 0.1 Mn 0.1O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. 10 mg of CuI was then evenly placed on the surface of the composite positive electrode and kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into a 9.5 mm diameter disc and placed on the other side of the electrolyte sheet. The disc was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as a5.

[0070] 6. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Add LiNi... 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. 10 mg of CuCl was then evenly placed on the surface of the composite positive electrode and kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into a 9.5 mm diameter disc and placed on the other side of the electrolyte sheet. The disc was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as a6.

[0071] 7. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Add LiNi... 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. 10 mg of Ag2S was then evenly placed on the surface of the composite positive electrode and kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium foil was cut into a 9.5 mm diameter disc and placed on the other side of the electrolyte sheet. The mixture was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as a7.

[0072] 8. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Add LiNi... 0.8 Co 0.1 Mn 0.1O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. 10 mg of AgCl was then evenly placed on the surface of the composite positive electrode and kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into a 9.5 mm diameter disc and placed on the other side of the electrolyte sheet. The mixture was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as a8.

[0073] 9. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Add LiNi... 0.8 Co 0.1 Mn 0.1 O2 and Li6PS5Cl were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. 10 mg of AgBr was then evenly placed on the surface of the composite positive electrode and kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium foil was cut into a 9.5 mm diameter disc and placed on the other side of the electrolyte sheet. The disc was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as a9.

[0074] Batteries a1-a9 were cycled once at 60℃ with a current of 0.2mA within a voltage range of 2.7V to 4.3V. After the cycle, the batteries were disassembled for characterization, and the cross-sectional observations are shown below.

[0075] Table 1

[0076] As shown in Table 1, in Example 1, no ion donor material was applied to the surface of the solid-state battery composite cathode in sample a1. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) revealed no ion migration pathways. This is because lithium-ion migration pathways in solid-state batteries cannot be observed using SEM-EDS; therefore, the window size corresponding to the ion pathway is 0, making it impossible to observe the ion migration of each component in the solid-state battery.

[0077] In samples a2-a9, ion donor materials were applied to the surface of the solid-state battery composite cathode under pressure. These ion donor materials were copper foil, copper powder, Cu2S, CuI, CuCl, Ag2S, AgCl, and AgBr, respectively. Ion migration paths were clearly observed under SEM-EDS. The window size for samples a2-a4 was 1 mm × 1 mm, for samples a5-a6 it was 500 μm × 500 μm, and for samples a7-a9 it was 100 μm × 100 μm.

[0078] It can be seen that when copper foil, copper powder, and Cu₂S are used as ion donor materials, the corresponding viewing window range is the largest, enabling the observation of ion migration paths in the positive electrode, electrolyte, and negative electrode of the solid-state battery. This achieves effective observation of the entire solid-state battery system and allows for graphical characterization of the entire system. This not only allows for effective analysis of the construction and failure mechanisms of ion pathways in the positive electrode of solid-state batteries but also provides a basis for the design of solid electrolyte components and the optimization of the entire solid-state battery system.

[0079] When CuI and CuCl are used as ion donor materials, their corresponding viewing windows are relatively large, enabling the observation of ion migration paths in the cathode and electrolyte of solid-state batteries. This allows for effective observation and graphical characterization of the cathode and electrolyte in solid-state batteries. This provides a basis for constructing ion pathways in the cathode of solid-state batteries, effectively analyzing failure mechanisms, and designing solid electrolyte components.

[0080] When Ag2S, AgCl, and AgBr are used as ion donor materials, their corresponding viewing window range is relatively small, but it is still possible to observe the ion migration path in the cathode of solid-state batteries. This enables effective observation and graphical characterization of the cathode of solid-state batteries, and allows for effective analysis of the construction and failure mechanism of ion pathways in the cathode of solid-state batteries.

[0081] In comparison, in the case of LiNi 0.8 Co 0.1 Mn 0.1In solid-state battery systems using O2 as the positive electrode active material and Li6PS5Cl as the solid electrolyte, when pressing ion donor materials onto the composite positive electrode surface, copper foil, copper powder, and Cu2S are the most effective ion donor materials, followed by CuI and CuCl, and then Ag2S, AgCl, and AgBr. This is because different ion donor materials have different abilities and types of ions they can provide. As materials for cuprous ion donors, copper foil, copper powder, Cu2S, CuI, and CuCl have different ionic conductivities, resulting in different rates and quantities of cuprous ions provided. Furthermore, the difference in ionic radius between silver ions and lithium ions is slightly greater than that between cuprous ions and lithium ions, leading to more similar migration paths for cuprous ions and lithium ions. Therefore, within the same solid-state lithium battery system, cuprous ions have stronger migration capabilities, resulting in a larger window for the donor materials providing cuprous ions in this solid-state battery system.

[0082] Figure 2-3 shows the SEM and EDS observation results of sample a3, which uses Cu powder as the ion donor material, with elemental copper powder uniformly placed on the surface of the composite cathode. Figure 2A shows a cross-sectional SEM image of the cathode, electrolyte, and copper powder of the solid-state battery before cycling. It can be seen that the copper powder is located at the top layer, with a thickness of about 10 μm; next is the cathode layer, with a thickness of about 30 μm; and then the electrolyte layer, with a thickness of more than 800 μm. Figure 2B shows a cross-sectional EDS spectrum of the cathode, electrolyte, and copper powder of the solid-state battery before cycling. Corresponding to Figure 2A, only the top 10 μm copper powder layer has a copper element signal.

[0083] After cycling, the solid-state battery was disassembled and characterized. Figure 3A shows a low-magnification scanning electron microscope (SEM) image of the positive electrode and electrolyte after cycling. It can be seen that the 10 μm copper powder layer above the positive electrode layer has disappeared, indicating that ion migration of copper powder on the positive electrode surface occurred during charge-discharge cycling. Figure 3B shows a low-magnification EDS image of the positive electrode and electrolyte after cycling. It can be seen that copper elements are distributed in the positive electrode layer and electrolyte layer, indicating that cuprous ions migrated into the lower positive electrode and electrolyte layers.

[0084] The area marked by the white box in Figure 3A was observed using high-magnification scanning electron microscopy and EDS energy dispersive spectroscopy. The results are shown in Figures 3C and 3D. Copper can be clearly observed at the electrolyte interface. Combined with XPS identification of the monovalent Cu signal in the electrolyte, it indicates that the copper powder on the cathode surface is converted into cuprous ions and undergoes ion migration in the solid-state battery system.

[0085] Example 2

[0086] The observation of ion pathways enabled failure analysis of solid-state cathodes.

[0087] This embodiment uses LiNi 0.8 Co0.1 Mn 0.1 Using O2 as the positive electrode active material, Li6PS5Cl as the solid electrolyte, and lithium metal as the negative electrode, a solid-state battery was assembled and cycled 100 times at room temperature with a current of 0.2 mA and a voltage range of 2.7 V–4.3 V. Significant capacity decay was observed after 100 cycles. Subsequently, copper powder, Cu2S, CuI, CuCl, Ag2S, AgCl, and AgBr were used as ion donor materials, pressed onto the surface of the positive electrode material, and the ion pathways of the cycled battery were characterized using the method of this embodiment. The results showed that the metal ions provided by the ion donor materials could migrate in the cycled solid-state battery and leave ion pathways after migration. By observing the ion pathways, the causes of solid-state battery failure can be analyzed. The method of this invention enables failure analysis of solid-state batteries after cycling.

[0088] The solid-state battery fabrication and testing processes are as follows:

[0089] 1. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Then, add LiNi... 0.8 Co 0.1 Mn 0.1 O2, Li6PS5Cl, and Super P were mixed uniformly in a mortar at a mass ratio of 7:3:1 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and held at 360 MPa for 10 min. A 50 μm thick lithium foil was cut into 9.5 mm diameter discs and placed on the other side of the electrolyte sheet, held at 120 MPa for 5 min. The resulting battery was designated b1. After 100 cycles at 0.2 mA within a voltage range of 2.7 V–4.3 V at room temperature, the battery was disassembled. 10 mg of copper powder was uniformly placed on the surface of the solid positive electrode and held at 360 MPa for 10 min. The battery was then reassembled. At 60 °C, the battery was charged to 4.3 V at 0.2 mA. After one charge, the battery's cross-sectional area was characterized.

[0090] 2. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Then, add LiNi... 0.8 Co 0.1 Mn 0.1O2, Li6PS5Cl, and Super P were mixed uniformly in a mortar at a mass ratio of 7:3:1 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and held at 360 MPa for 10 min. A 50 μm thick lithium foil was cut into 9.5 mm diameter discs and placed on the other side of the electrolyte sheet, held at 120 MPa for 5 min. This resulting battery was designated b2. After 100 cycles at 0.2 mA within a voltage range of 2.7 V–4.3 V at room temperature, the battery was disassembled. 10 mg of Cu2S was uniformly placed on the surface of the solid positive electrode and held at 360 MPa for 10 min. The battery was then reassembled. At 60 °C, the battery was charged to 4.3 V at 0.2 mA. After one charge, the battery's cross-sectional area was characterized.

[0091] 3. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Then, add LiNi... 0.8 Co 0.1 Mn 0.1 O2, Li6PS5Cl, and Super P were mixed uniformly in a mortar at a mass ratio of 7:3:1 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and held at 360 MPa for 10 min. A 50 μm thick lithium foil was cut into 9.5 mm diameter discs and placed on the other side of the electrolyte sheet. The mixture was held at 120 MPa for 5 min. The resulting battery was designated b3. After 100 cycles at 0.2 mA within a voltage range of 2.7 V–4.3 V at room temperature, the battery was disassembled. 10 mg of CuI was uniformly placed on the surface of the solid positive electrode and held at 360 MPa for 10 min. The battery was then reassembled. At 60 °C, the battery was charged to 4.3 V at 0.2 mA. After one charge, the battery's cross-sectional characteristics were characterized.

[0092] 4. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Add LiNi... 0.8 Co 0.1 Mn 0.1O2, Li6PS5Cl, and Super P were mixed uniformly in a mortar at a mass ratio of 7:3:1 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and held at 360 MPa for 10 min. A 50 μm thick lithium foil was cut into 9.5 mm diameter discs and placed on the other side of the electrolyte sheet. The mixture was held at 120 MPa for 5 min. The resulting battery was designated b4. After 100 cycles at 0.2 mA within a voltage range of 2.7 V–4.3 V at room temperature, the battery was disassembled. 10 mg of CuCl was uniformly placed on the surface of the solid positive electrode and held at 360 MPa for 10 min. The battery was then reassembled. At 60 °C, the battery was charged to 4.3 V at 0.2 mA. After one charge, the battery's cross-section was characterized.

[0093] 5. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Add LiNi... 0.8 Co 0.1 Mn 0.1 O2, Li6PS5Cl, and Super P were mixed uniformly in a mortar at a mass ratio of 7:3:1 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and held at 360 MPa for 10 min. A 50 μm thick lithium foil was cut into 9.5 mm diameter discs and placed on the other side of the electrolyte sheet. The mixture was held at 120 MPa for 5 min. The resulting battery was designated b5. After 100 cycles at 0.2 mA within a voltage range of 2.7 V–4.3 V at room temperature, the battery was disassembled. 10 mg of Ag2S was uniformly placed on the surface of the solid positive electrode and held at 360 MPa for 10 min. The battery was then reassembled. At 60 °C, the battery was charged to 4.3 V at 0.2 mA. After one charge, the battery's cross-sectional area was characterized.

[0094] 6. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Add LiNi... 0.8 Co 0.1 Mn 0.1O2, Li6PS5Cl, and Super P were mixed uniformly in a mortar at a mass ratio of 7:3:1 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and held at 360 MPa for 10 min. A 50 μm thick lithium foil was cut into 9.5 mm diameter discs and placed on the other side of the electrolyte sheet, held at 120 MPa for 5 min. The resulting battery was designated b6. After 100 cycles at 0.2 mA within a voltage range of 2.7 V–4.3 V at room temperature, the battery was disassembled. 10 mg of AgCl was uniformly placed on the surface of the solid positive electrode and held at 360 MPa for 10 min. The battery was then reassembled. At 60 °C, the battery was charged to 4.3 V at 0.2 mA. After one charge, the battery's cross-sectional characteristics were characterized.

[0095] 7. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Add LiNi... 0.8 Co 0.1 Mn 0.1 O2, Li6PS5Cl, and Super P were mixed uniformly in a mortar at a mass ratio of 7:3:1 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and held at 360 MPa for 10 min. A 50 μm thick lithium foil was cut into 9.5 mm diameter discs and placed on the other side of the electrolyte sheet. The mixture was held at 120 MPa for 5 min. The resulting battery was designated b7. After 100 cycles at 0.2 mA within a voltage range of 2.7 V–4.3 V at room temperature, the battery was disassembled. 10 mg of AgBr was uniformly placed on the surface of the solid positive electrode and held at 360 MPa for 10 min. The battery was then reassembled. At 60 °C, the battery was charged to 4.3 V at 0.2 mA. After one charge, the battery's cross-sectional characteristics were characterized.

[0096] Table 2

[0097] As shown in Table 2, copper powder, Cu2S, CuI, CuCl, Ag2S, AgCl, and AgBr were used as ion donor materials in samples b1-b7, respectively. After 100 charge-discharge cycles, the above ion donor materials were pressed onto the surface of the positive electrode, reassembled, and charged once. Cu or Ag ion pathways in the positive electrode of the solid-state battery were observed in samples b1-b7 under SEM and EDS. Taking sample b2 as an example, Figure 4 shows the SEM-EDS energy dispersive spectroscopy (EDS) spectrum of the ion pathways in the electrolyte after battery cycle b2. Among them, Figure 4(a) is the SEM image of Cu2S ion donor material pressed onto the surface of the positive electrode material and charged; element S in Figure 4(b) is the characteristic element of the solid electrolyte Li6PS5Cl, and its EDS image represents the electrolyte; element Ni in Figure 4(d) is the positive electrode material LiNi. 0.8 Co 0.1 Mn 0.1 The characteristic element of O2, its EDS image represents the positive electrode particles. The positions of the solid electrolyte and positive electrode particles can be seen from the image. As shown in Figure 4(a), after cycling, the electrolyte in the solid-state battery positive electrode partially cracks. The EDS image of Cu in Figure 4(c) represents the ion path of cuprous ions. It can be seen that the copper element is only distributed on one side of the cracked electrolyte, indicating that the ion path is interrupted in the electrolyte and does not reach the position of the Ni element in Figure 4(d), indicating that the ions cannot be conducted to the surface of the positive electrode particles. This figure shows that after cycling, the ion path in the solid-state battery positive electrode is broken in the electrolyte and cannot be conducted to the surface of the positive electrode particles. Cracking of the solid electrolyte was observed in samples b1-b7, leading to the breakage of the ion path in the electrolyte and the loss of contact between the solid electrolyte and the positive electrode active material, resulting in the breakage of the ion path between the electrolyte and the active material. This fully demonstrates that the failure of the solid-state battery in this case is due to the cracking of the solid electrolyte in the composite positive electrode and the interruption of the ion path caused by the failure of the contact between the solid electrolyte and the positive electrode active material. This is the main reason for the failure of the solid-state battery positive electrode.

[0098] Example 3

[0099] Ion pathways in solid electrolytes - distinguishing grain boundary / bulk transport

[0100] This embodiment uses Cu₂S as the ion donor material to illustrate the role of metal element ions (with Cu₂S as the ion donor). + For example, ions can migrate in different solid electrolytes and leave migration paths after migration, thus tracing ion pathways in solid electrolytes. Furthermore, the minimum resolution for observing ion pathways meets the minimum scale required for characterizing solid electrolytes, thereby enabling the study of transport pathways in solid electrolytes (e.g., ion transport at grain boundaries and in the bulk phase), guiding the synthesis and application of solid electrolytes.

[0101] Li6PS5Cl, PEO-LiTFSI (polyoxyethylene solid polymer electrolyte, with lithium bis(trifluoromethanesulfonyl)imide as the lithium salt), and LLZTO (Li 6.75 La3Zr 1.5 Ta 0.5 O 12 Using lithium lanthanum zirconium tantalum oxide electrolyte as the solid electrolyte, an ion donor material is uniformly coated on the surface of the solid electrolyte as the positive electrode, and metallic lithium is used as the negative electrode to assemble a solid-state battery. The solid electrolyte is then characterized after cycling.

[0102] 1. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain this pressure at 360 MPa for 10 min to obtain a solid electrolyte sheet. Weigh 10 mg of Cu2S and evenly distribute it on the surface of the solid electrolyte sheet. Maintain this pressure at 360 MPa for 10 min. Cut a 50 μm thick lithium foil into a 9.5 mm diameter disc and place it on the other side of the electrolyte sheet. Maintain this pressure at 120 MPa for 5 min. The resulting battery is denoted as c1.

[0103] 2. Add 67 mL of acetonitrile to a mixing tank, then add 1.76 g of PEO and 0.574 g of LiTFSI, and stir thoroughly to dissolve them in the acetonitrile. Coat the electrolyte slurry evenly onto a PTFE template, allow it to stand at room temperature for 24 h to evaporate the acetonitrile, and then dry it in a 70°C oven for 12 h. After cooling to room temperature, punch the dried electrolyte membrane into a 10 mm diameter disc and quickly transfer it to an argon-filled glove box for storage. Weigh 10 mg of Cu₂S and evenly place it on the surface of the solid electrolyte, and maintain it at 360 MPa for 10 min. Cut a 50 μm thick lithium metal foil into a 9.5 mm diameter disc, place it on the other side of the electrolyte disc, and maintain it at 120 MPa for 5 min. The resulting battery is denoted as C₂.

[0104] 3. Weigh 100 mg of LLZTO powder and place it in a 10 mm diameter PTFE sleeve. Maintain the pressure at 360 MPa for 10 min to obtain a solid electrolyte powder sheet. Place the solid electrolyte powder sheet in a muffle furnace and calcine at 950 °C for 8 h. After cooling to room temperature with the furnace, obtain a solid oxide electrolyte sheet. Weigh 10 mg of Cu₂S and evenly place it on the surface of the solid electrolyte, and maintain the pressure at 360 MPa for 10 min. Cut a 50 μm thick lithium metal foil into a 9.5 mm diameter disc and place it on the other side of the electrolyte sheet. Maintain the pressure at 120 MPa for 5 min. The resulting battery is denoted as C3.

[0105] Batteries C1-C3 were charged to 4.3V at 0.2mA at 60℃. After charging was completed, the batteries were disassembled for characterization, and the cross-sectional observations are shown below.

[0106] Table 3

[0107] The results in Table 3 show that in samples c1-c3, with Cu₂S ion donor material as the positive electrode, Li₆PS₅Cl, PEO-LiTFSI, and LLZTO as solid electrolytes, and lithium metal as the negative electrode, the observations were conducted after one charge of the solid-state battery. Cu ion pathways were observed in samples c1-c3 under both SEM and EDS. Taking sample c1 as an example, as shown in Figure 5, the white stripes represent the EDS spectrum signal of copper. The copper stripes indicate that this is a region enriched during the migration of cuprous ions, representing the ion pathway in the solid electrolyte. Furthermore, the copper stripes basically coincide with the Li₆PS₅Cl electrolyte particle boundaries (i.e., grain boundaries) observed under scanning electron microscopy, indicating that under these conditions, ion transport in the solid electrolyte is mainly concentrated at the grain boundaries.

[0108] Example 4

[0109] Multiple Ion Pathways in Cathodes - Guiding Solid-State Cathode Construction

[0110] In this embodiment, Cu₂S is used as the ion donor material, along with Li₂S, S, MoS₂, VS₂, VS₄, FeS₂, SPAN (sulfurized polyacrylonitrile), and LiNi. 0.8 Co 0.1 Mn 0.1 O2 and LiFePO4 were used as positive electrode active materials. This study demonstrates that the method can be used to trace ion pathways in the positive electrode for various positive electrode active materials, and that the observation of ion pathways can guide the construction of solid-state positive electrodes. Using the above materials as positive electrode active materials, and uniformly coating the positive electrode with Cu2S as an ion donor, Li6PS5Cl as a solid electrolyte, and lithium metal as the negative electrode, a solid-state battery was assembled.

[0111] 1. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain this mixture at 360 MPa for 10 min to obtain a solid electrolyte sheet. Mix Li2S, Li6PS5Cl, and Super P in a mortar at a mass ratio of 1:1:1 to form a composite positive electrode. Weigh 10 mg of this mixture and place it on one side of the electrolyte sheet. Maintain this mixture at 360 MPa for 10 min. Weigh 10 mg of Cu2S and evenly distribute it on the surface of the solid positive electrode. Maintain this mixture at 360 MPa for 10 min. Cut a 50 μm thick lithium metal foil into a 9.5 mm diameter disc and place it on the other side of the electrolyte sheet. Maintain this mixture at 120 MPa for 5 min. The resulting battery is denoted as d1.

[0112] 2. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain this mixture at 360 MPa for 10 min to obtain a solid electrolyte sheet. Mix S, Li6PS5Cl, and Super P in a mortar at a mass ratio of 1:1:1 to form a composite positive electrode. Weigh 10 mg of this mixture and place it on one side of the electrolyte sheet, maintaining this mixture at 360 MPa for 10 min. Weigh 10 mg of Cu2S and evenly distribute it on the surface of the solid positive electrode, maintaining this mixture at 360 MPa for 10 min. Cut a 50 μm thick lithium metal foil into a 9.5 mm diameter disc and place it on the other side of the solid electrolyte sheet. Maintain this mixture at 120 MPa for 5 min. The resulting battery is denoted as d2.

[0113] 3. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain this mixture at 360 MPa for 10 min to obtain a solid electrolyte sheet. Mix MoS2, Li6PS5Cl, and Super P in a mortar at a mass ratio of 1:1:1 to form a composite positive electrode. Weigh 10 mg of this mixture and place it on one side of the electrolyte sheet, maintaining this mixture at 360 MPa for 10 min. Weigh 10 mg of Cu2S and evenly distribute it on the surface of the solid positive electrode, maintaining this mixture at 360 MPa for 10 min. Cut a 50 μm thick lithium metal foil into a 9.5 mm diameter disc and place it on the other side of the solid electrolyte sheet. Maintain this mixture at 120 MPa for 5 min. The resulting battery is denoted as d3.

[0114] 4. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Mix VS2, Li6PS5Cl, and Super P in a mortar at a mass ratio of 1:1:1 to form a composite positive electrode. Weigh 10 mg of this mixture and place it on one side of the electrolyte sheet, maintaining a pressure of 360 MPa for 10 min. Weigh 10 mg of Cu2S and evenly place it on the surface of the solid positive electrode, maintaining a pressure of 360 MPa for 10 min. Cut a 50 μm thick lithium metal foil into a 9.5 mm diameter disc and place it on the other side of the solid electrolyte sheet. Maintain a pressure of 120 MPa for 5 min. The resulting battery is denoted as d4.

[0115] 5. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain this mixture at 360 MPa for 10 min to obtain a solid electrolyte sheet. Mix VS4, Li6PS5Cl, and Super P in a mortar at a mass ratio of 1:1:1 to obtain a composite positive electrode. Weigh 10 mg of this mixture and place it on one side of the electrolyte sheet. Maintain this mixture at 360 MPa for 10 min. Weigh 10 mg of Cu2S and evenly place it on the surface of the solid positive electrode. Maintain this mixture at 360 MPa for 10 min. Cut a 50 μm thick lithium metal foil into a 9.5 mm diameter disc and place it on the other side of the solid electrolyte sheet. Maintain this mixture at 120 MPa for 5 min. The resulting battery is denoted as d5.

[0116] 6. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain this mixture at 360 MPa for 10 min to obtain a solid electrolyte sheet. Mix FeS2, Li6PS5Cl, and Super P in a mortar at a mass ratio of 1:1:1 to form a composite positive electrode. Weigh 10 mg of this mixture and place it on one side of the electrolyte sheet. Maintain this mixture at 360 MPa for 10 min. Weigh 10 mg of Cu2S and evenly distribute it on the surface of the solid positive electrode. Maintain this mixture at 360 MPa for 10 min. Cut a 50 μm thick lithium metal foil into a 9.5 mm diameter disc and place it on the other side of the solid electrolyte sheet. Maintain this mixture at 120 MPa for 5 min. The resulting battery is denoted as d6.

[0117] 7. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain this mixture at 360 MPa for 10 min to obtain a solid electrolyte sheet. Mix SPAN, Li6PS5Cl, and Super P in a mortar at a mass ratio of 1:1:1 to form a composite positive electrode. Weigh 10 mg of this mixture and place it on one side of the electrolyte sheet. Maintain this mixture at 360 MPa for 10 min. Weigh 10 mg of Cu2S and evenly distribute it on the surface of the solid positive electrode. Maintain this mixture at 360 MPa for 10 min. Cut a 50 μm thick lithium metal foil into a 9.5 mm diameter disc and place it on the other side of the solid electrolyte sheet. Maintain this mixture at 120 MPa for 5 min. The resulting battery is denoted as d7.

[0118] 8. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte sheet. Add LiNi... 0.8 Co 0.1 Mn 0.1 O2, Li6PS5Cl, and Super P were mixed evenly in a mortar at a mass ratio of 7:3:1 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. 10 mg of Cu2S was then evenly placed on the surface of the solid positive electrode and kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium foil was cut into a 9.5 mm diameter disc and placed on the other side of the solid electrolyte sheet. The disc was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as d8.

[0119] 9. Weigh 100 mg of Li6PS5Cl and place it in a 10 mm diameter PTFE sleeve. Maintain this pressure at 360 MPa for 10 min to obtain a solid electrolyte sheet. Mix LiFePO4, Li6PS5Cl, and Super P in a mortar at a mass ratio of 7:3:1 to form a composite positive electrode. Weigh 10 mg of this mixture and place it on one side of the electrolyte sheet, maintaining this pressure at 360 MPa for 10 min. Weigh 10 mg of Cu2S and uniformly place it on the surface of the solid positive electrode, maintaining this pressure at 360 MPa for 10 min. Cut a 50 μm thick lithium metal foil into a 9.5 mm diameter disc and place it on the other side of the solid electrolyte sheet. Maintain this pressure at 120 MPa for 5 min. The resulting battery is denoted as d9.

[0120] Batteries d1-d9 underwent EIS impedance testing at room temperature. Subsequently, batteries d1-d9 were charged to 4.3V at 0.2mA at 60℃. After charging, the batteries were disassembled for characterization, and the cross-sectional observations are shown below.

[0121] Table 4

[0122] As shown in Table 4, the positive electrode active materials in samples d1-d9 are Li2S, S, MoS2, VS2, VS4, FeS2, SPAN, and LiNi, respectively. 0.8 Co 0.1 Mn 0.1 O2 and LiFePO4 were pressed onto the cathode surface as Cu2S ion donor materials. Cu ion pathways in the battery could be observed in samples d1-d9 under SEM and EDS.

[0123] Observations of the copper ion transport pathways in samples d1-d9 revealed that different active cathode materials exhibited varying performance when ground and mixed with the same solid electrolyte material, Li6PS5Cl, to form composite cathode materials. When Li2S, S, VS2, and VS4 were used to form composite cathode materials, the Cu ion pathway could not reach 80% of the cathode material surface. This indicates that the grinding and mixing method for forming composite cathode materials is not suitable for these materials, failing to achieve uniform mixing of the electrolyte and active materials, thus hindering the construction of effective ion pathways in the solid cathode. Therefore, the grinding and mixing method cannot effectively construct composite cathodes for these materials. Furthermore, MoS2, FeS2, SPAN (sulfurized polyacrylonitrile), and LiNi... 0.8 Co 0.1 Mn 0.1 When O2, LiFePO4 and other five positive electrode active materials are used to form a composite positive electrode material, Cu ions can reach more than 80% of the surface of the positive electrode material. Therefore, the above five materials are suitable for mixing with solid electrolytes by grinding to form a positive electrode composite material.

[0124] Furthermore, impedance testing of d1-d9 batteries also verified the above viewpoints. Batteries assembled with composite cathode materials (Li2S, S, VS2, VS4) and solid electrolytes through a grinding and mixing method exhibited higher impedance (>1000Ω), while those assembled with MoS2, FeS2, SPAN (sulfurized polyacrylonitrile), and LiNi... 0.8 Co 0.1 Mn 0.1 The battery impedance of composite cathode assemblies formed by grinding and mixing five positive electrode active materials, including O2 and LiFePO4, with solid electrolytes all has a value of less than 200Ω. Therefore, observing the ion pathways in ion donor materials can effectively guide the construction of positive electrode material systems, thereby contributing to the research and development of battery systems.

[0125] Taking sample d8 as an example, Figure 6 shows the SEM-EDS energy dispersive spectroscopy (EDS) spectrum of the ion pathways in the positive electrode of battery d8. Figure 6(a) is the SEM image of battery d8, showing the positions of the electrolyte and positive electrode particles. Element S in Figure 6(b) is a characteristic element of the solid electrolyte Li6PS5Cl; therefore, the EDS image of S in Figure 6(b) represents the electrolyte. Element Ni in Figure 6(d) is the positive electrode material LiNi. 0.8 Co 0.1 Mn 0.1 O2 is a characteristic element; therefore, the EDS image of Ni in Figure 6(d) represents the cathode particles. Figure 6(c) shows the EDS image of Cu, representing the ion migration path of cuprous ions, reflecting the ion migration path in the solid-state battery cathode. As can be seen from Figures 6(b) and 6(c), the ion path represented by copper essentially reaches the surface of all solid-state battery cathode material particles, which fully demonstrates the effective construction of ion pathways in this solid-state battery cathode. This indicates that the LiNi constructed using the grinding method... 0.8 Co 0.1 Mn 0.1 In the O2-Li6PS5Cl composite cathode system, ions can reach more than 80% of the cathode particle surface. Therefore, it is feasible to construct the cathode composite system by grinding.

[0126] Example 5

[0127] The method of the present invention is applicable to polymer systems.

[0128] This embodiment uses copper powder, Cu₂S, CuI, CuCl, Ag₂S, AgCl, and AgBr as ion donor materials and PEO-LiTFSI as a solid polymer electrolyte to demonstrate that this method is applicable to the characterization of ion pathways in polymer-based solid-state batteries. LiNi 0.8 Co 0.1 Mn 0.1 O2 is used as the positive electrode active material, the above-mentioned substances are used as ion donor materials, PEO-LiTFSI is used as the solid electrolyte, and lithium metal is used as the negative electrode to assemble a solid-state battery.

[0129] 1. Add 67 mL of acetonitrile to a mixing tank, then add 1.76 g of PEO and 0.574 g of LiTFSI, and stir thoroughly to dissolve them in the acetonitrile. Coat the electrolyte slurry evenly onto a PTFE template, allow it to stand at room temperature for 24 h to evaporate the acetonitrile, and then dry it in a 70°C oven for 12 h. After cooling to room temperature, punch the dried solid electrolyte membrane into a 16 mm diameter disc and quickly transfer it to an argon-filled glove box for storage. Mix PEO and LiTFSI uniformly at a mass ratio of 3.07:1 to obtain PEO-LiTFSI. Add LiNi... 0.8 Co 0.1 Mn0.1 O2 and PEO-LiTFSI were added to acetonitrile at a 1:1 mass ratio, stirred thoroughly to ensure uniform dispersion, and then added to a mixing tank. After stirring again, the composite positive electrode slurry was evenly coated onto the surface of aluminum foil and dried in an oven at 55°C for 6 hours. The dried composite positive electrode sheet was punched into a 12mm diameter disc and placed in a vacuum oven at 120°C for 6 hours. After the temperature dropped to room temperature, the electrode sheet was quickly transferred to an argon-filled glove box for storage. A battery was fabricated using the composite positive electrode sheet, a solid electrolyte membrane, and a metallic Li sheet; the resulting battery is denoted as e1.

[0130] 2. Add 67 mL of acetonitrile to a mixing tank, then add 1.76 g of PEO and 0.574 g of LiTFSI, and stir thoroughly to dissolve them in the acetonitrile. Coat the solid electrolyte slurry evenly onto a PTFE template, allow it to stand at room temperature for 24 h to evaporate the acetonitrile, and then dry it in a 70℃ oven for 12 h. After cooling to room temperature, punch the dried solid electrolyte membrane into a 16 mm diameter disc and quickly transfer it to an argon-filled glove box for storage. Mix PEO and LiTFSI uniformly at a mass ratio of 3.07:1 to obtain PEO-LiTFSI. Add LiNi... 0.8 Co 0.1 Mn 0.1 O2 and PEO-LiTFSI were added to acetonitrile at a 1:1 mass ratio, stirred thoroughly to ensure uniform dispersion, and then added to a mixing tank. After stirring again, the composite positive electrode slurry was evenly coated onto the surface of aluminum foil and dried in a 55℃ oven for 6 hours. The dried composite positive electrode sheet was punched into a 12mm diameter disc and placed in a vacuum oven at 120℃ for 6 hours. After the temperature dropped to room temperature, the electrode sheet was quickly transferred to an argon-filled glove box for storage. A battery was fabricated using the composite positive electrode sheet, a solid electrolyte membrane, and a metallic Li sheet. 10mg of copper powder, the ion donor material, was evenly covered and pressed onto the surface of the positive electrode. The resulting battery was denoted as e2.

[0131] 3. Add 67 mL of acetonitrile to a mixing tank, then add 1.76 g of PEO and 0.574 g of LiTFSI, and stir thoroughly to dissolve them in the acetonitrile. Coat the solid electrolyte slurry evenly onto a PTFE template, allow it to stand at room temperature for 24 h to evaporate the acetonitrile, and then dry it in a 70℃ oven for 12 h. After cooling to room temperature, punch the dried electrolyte membrane into a 16 mm diameter disc and quickly transfer it to an argon-filled glove box for storage. Mix PEO and LiTFSI uniformly at a mass ratio of 3.07:1 to obtain PEO-LiTFSI. Add LiNi... 0.8 Co 0.1 Mn 0.1O2 and PEO-LiTFSI were added to acetonitrile at a 1:1 mass ratio, stirred thoroughly to ensure uniform dispersion, and then added to a mixing tank. After stirring again, the composite positive electrode slurry was evenly coated onto the surface of aluminum foil and dried in a 55℃ oven for 6 hours. The dried composite positive electrode sheet was punched into a 12mm diameter disc and placed in a vacuum oven at 120℃ for 6 hours. After the temperature dropped to room temperature, the electrode sheet was quickly transferred to an argon-filled glove box for storage. A battery was fabricated using the composite positive electrode sheet, electrolyte membrane, and metallic Li sheet. 10mg of Cu2S ion donor material was evenly covered and pressed onto the surface of the positive electrode. The resulting battery was denoted as e3.

[0132] 4. Add 67 mL of acetonitrile to a mixing tank, then add 1.76 g of PEO and 0.574 g of LiTFSI, and stir thoroughly to dissolve them in the acetonitrile. Coat the solid electrolyte slurry evenly onto a PTFE template, allow it to stand at room temperature for 24 h to evaporate the acetonitrile, and then dry it in a 70°C oven for 12 h. After cooling to room temperature, punch the dried electrolyte membrane into 16 mm diameter discs and quickly transfer them to an argon-filled glove box for storage. Mix PEO and LiTFSI uniformly at a mass ratio of 3.07:1 to obtain PEO-LiTFSI. Add LiNi... 0.8 Co 0.1 Mn 0.1 O2 and PEO-LiTFSI were added to acetonitrile at a mass ratio of 1:1, stirred thoroughly to ensure uniform dispersion, and then added to a mixing tank. After stirring again, the composite positive electrode slurry was evenly coated onto the surface of aluminum foil and dried in an oven at 55°C for 6 hours. The dried composite positive electrode sheet was punched into a 12mm diameter disc and placed in a vacuum oven at 120°C for 6 hours. After the temperature dropped to room temperature, the electrode sheet was quickly transferred to an argon-filled glove box for storage. A battery was fabricated using the composite positive electrode sheet, electrolyte membrane, and metallic Li sheet. 10mg of CuI ion donor material was evenly covered and pressed onto the surface of the positive electrode. The resulting battery was denoted as e4.

[0133] 5. Add 67 mL of acetonitrile to a mixing tank, then add 1.76 g of PEO and 0.574 g of LiTFSI, and stir thoroughly to dissolve them in the acetonitrile. Coat the solid electrolyte slurry evenly onto a PTFE template, allow it to stand at room temperature for 24 h to evaporate the acetonitrile, and then dry it in a 70°C oven for 12 h. After cooling to room temperature, punch the dried solid electrolyte membrane into 16 mm diameter discs and quickly transfer them to an argon-filled glove box for storage. Mix PEO and LiTFSI uniformly at a mass ratio of 3.07:1 to obtain PEO-LiTFSI. Add LiNi... 0.8 Co 0.1 Mn 0.1O2 and PEO-LiTFSI were added to acetonitrile at a 1:1 mass ratio, stirred thoroughly to ensure uniform dispersion, and then added to a mixing tank. After stirring again, the composite positive electrode slurry was evenly coated onto the surface of aluminum foil and dried in an oven at 55°C for 6 hours. The dried composite positive electrode sheet was punched into a 12mm diameter disc and placed in a vacuum oven at 120°C for 6 hours. After the temperature dropped to room temperature, the electrode sheet was quickly transferred to an argon-filled glove box for storage. A battery was fabricated using the composite positive electrode sheet, a solid electrolyte membrane, and a metallic Li sheet. 10mg of CuCl ion donor material was evenly covered and pressed onto the surface of the positive electrode. The resulting battery was designated e5.

[0134] 6. Add 67 mL of acetonitrile to a mixing tank, then add 1.76 g of PEO and 0.574 g of LiTFSI, stirring thoroughly to dissolve them in the acetonitrile. Coat the solid electrolyte slurry evenly onto a PTFE template, allow it to stand at room temperature for 24 h to evaporate the acetonitrile, and then dry it in a 70°C oven for 12 h. After cooling to room temperature, punch the dried solid electrolyte membrane into 16 mm diameter discs and quickly transfer them to an argon-filled glove box for storage. Mix PEO and LiTFSI uniformly at a mass ratio of 3.07:1 to obtain PEO-LiTFSI. Add LiNi... 0.8 Co 0.1 Mn 0.1 O2 and PEO-LiTFSI were added to acetonitrile at a 1:1 mass ratio, stirred thoroughly to ensure uniform dispersion, and then added to a mixing tank. After stirring again, the composite positive electrode slurry was evenly coated onto the surface of aluminum foil and dried in a 55℃ oven for 6 hours. The dried composite positive electrode sheet was punched into a 12mm diameter disc and placed in a vacuum oven at 120℃ for 6 hours. After the temperature dropped to room temperature, the electrode sheet was quickly transferred to an argon-filled glove box for storage. A battery was fabricated using the composite positive electrode sheet, electrolyte membrane, and metallic Li sheet. 10mg of Ag2S ion donor material was evenly covered and pressed onto the surface of the positive electrode. The resulting battery was designated e6.

[0135] 7. Add 67 mL of acetonitrile to a mixing tank, then add 1.76 g of PEO and 0.574 g of LiTFSI, and stir thoroughly to dissolve them in the acetonitrile. Coat the solid electrolyte slurry evenly onto a PTFE template, allow it to stand at room temperature for 24 h to evaporate the acetonitrile, and then dry it in a 70°C oven for 12 h. After cooling to room temperature, punch the dried solid electrolyte membrane into a 16 mm diameter disc and quickly transfer it to an argon-filled glove box for storage. Mix PEO and LiTFSI uniformly at a mass ratio of 3.07:1 to obtain PEO-LiTFSI. Add LiNi... 0.8 Co 0.1 Mn 0.1O2 and PEO-LiTFSI were added to acetonitrile at a 1:1 mass ratio, stirred thoroughly to ensure uniform dispersion, and then added to a mixing tank. After stirring again, the composite positive electrode slurry was evenly coated onto the surface of aluminum foil and dried in a 55℃ oven for 6 hours. The dried composite positive electrode sheet was punched into a 12mm diameter disc and placed in a vacuum oven at 120℃ for 6 hours. After the temperature dropped to room temperature, the electrode sheet was quickly transferred to an argon-filled glove box for storage. A battery was fabricated using the composite positive electrode sheet, electrolyte membrane, and metallic Li sheet. 10mg of AgCl ion donor material was evenly covered and pressed onto the surface of the positive electrode. The resulting battery was designated e7.

[0136] 8. Add 67 mL of acetonitrile to a mixing tank, then add 1.76 g of PEO and 0.574 g of LiTFSI, and stir thoroughly to dissolve them in the acetonitrile. Coat the solid electrolyte slurry evenly onto a PTFE template, allow it to stand at room temperature for 24 h to evaporate the acetonitrile, and then dry it in a 70°C oven for 12 h. After cooling to room temperature, punch the dried solid electrolyte membrane into 16 mm diameter discs and quickly transfer them to an argon-filled glove box for storage. Mix PEO and LiTFSI uniformly at a mass ratio of 3.07:1 to obtain PEO-LiTFSI. Add LiNi... 0.8 Co 0.1 Mn 0.1 O2 and PEO-LiTFSI were added to acetonitrile at a 1:1 mass ratio, stirred thoroughly to ensure uniform dispersion, and then added to a mixing tank. After stirring again, the composite positive electrode slurry was evenly coated onto the surface of aluminum foil and dried in a 55℃ oven for 6 hours. The dried composite positive electrode sheet was punched into a 12mm diameter disc and placed in a vacuum oven at 120℃ for 6 hours. After the temperature dropped to room temperature, the electrode sheet was quickly transferred to an argon-filled glove box for storage. A battery was fabricated using the composite positive electrode sheet, a solid electrolyte membrane, and a metallic Li sheet. 10mg of AgBr ion donor material was evenly covered and pressed onto the surface of the positive electrode. The resulting battery was designated e8.

[0137] Batteries e1-e8 were cycled once at 60°C with a current of 0.2mA within a voltage range of 2.7V to 4.3V. After the cycle, the batteries were disassembled for characterization, and the cross-sectional observations are shown below.

[0138] Table 5

[0139] As can be seen from the results in Table 5, in the solid-state battery of Example 5, the positive electrode active material is LiNi. 0.8 Co 0.1 Mn 0.1O2 was used, and the solid electrolyte was PEO-LiTFSI. In sample e1, no ion donor material was applied to the surface of the solid-state battery composite cathode. No ion migration pathways were observed using energy-dispersive scanning electron microscopy (SEM-EDS). This is because lithium-ion migration pathways in polymer solid-state batteries cannot be observed using SEM-EDS, thus making it impossible to observe the ion migration of individual components within the solid-state battery. In samples e2-e8, ion donor materials were applied to the surface of the solid-state battery composite cathode using a pressurized method. These ion donor materials were copper powder, Cu2S, CuI, CuCl, Ag2S, AgCl, and AgBr, respectively. Ion migration pathways were clearly observed under SEM-EDS in all of these samples.

[0140] As shown in Figure 7, the observation results for sample e2, which uses Cu powder as the ion donor material, show that elemental copper powder was uniformly placed on the surface of the composite positive electrode. The figure reveals that the originally silvery-white negative electrode surface is covered with a black substance, which is the reduction product of cuprous ions migrating from the positive electrode side and passing through the polymer electrolyte. The originally transparent polymer electrolyte sheet turns black, indicating that some cuprous ions remain in the polymer electrolyte. This evidence suggests that cuprous ions can reach the negative electrode surface through the PEO-LiTFSI polymer electrolyte. Therefore, the tracer method of this invention is applicable to polymer electrolytes, and thus suitable for the performance characterization of polymer solid-state batteries.

[0141] Example 6

[0142] The method of the present invention is applicable to oxide systems.

[0143] This embodiment uses copper powder, Cu₂S, CuI, CuCl, Ag₂S, AgCl, and AgBr as ion donor materials and LLZTO as an oxide solid electrolyte to illustrate that in an oxide-based solid-state battery, metal ions from the ion donor material can move within the solid cathode, and to trace the ion pathways within the cathode. LiNi is used as an example. 0.8 Co 0.1 Mn 0.1 O2 is used as the positive electrode active material, the above-mentioned substances are used as ion donor materials, LLZTO is used as the solid electrolyte, and lithium metal is used as the negative electrode to assemble a solid-state battery.

[0144] 1. Weigh 100 mg of LLZTO powder and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte powder sheet. Place the solid electrolyte powder sheet in a muffle furnace and calcine at 950 °C for 8 h. After cooling to room temperature with the furnace, obtain a solid oxide electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1O2 and LLZTO powder were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of the mixture was weighed and placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into a 9.5 mm diameter disc and placed on the other side of the electrolyte sheet. The disc was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as f1.

[0145] 2. Weigh 100 mg of LLZTO powder and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte powder sheet. Place the solid electrolyte powder sheet in a muffle furnace and calcine at 950 °C for 8 h. After cooling to room temperature with the furnace, obtain a solid oxide electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2 and LLZTO powder were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the solid electrolyte sheet, and 10 mg of copper powder, the ion donor material, was evenly placed on the surface of the solid positive electrode. The mixture was kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into a 9.5 mm diameter disc and placed on the other side of the solid electrolyte sheet. The mixture was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as f2.

[0146] 3. Weigh 100 mg of LLZTO powder and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte powder sheet. Place the solid electrolyte powder sheet in a muffle furnace and calcine at 950 °C for 8 h. After cooling to room temperature with the furnace, obtain a solid oxide electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2 and LLZTO powder were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet, and 10 mg of Cu2S ion donor material was evenly placed on the surface of the solid positive electrode. The mixture was kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into a 9.5 mm diameter disc and placed on the other side of the solid electrolyte sheet. The mixture was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as f3.

[0147] 4. Weigh 100 mg of LLZTO powder and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte powder sheet. Place the solid electrolyte powder sheet in a muffle furnace and calcine at 950 °C for 8 h. After cooling to room temperature with the furnace, obtain a solid oxide electrolyte sheet. (The last sentence appears to be incomplete and possibly refers to LiNi...) 0.8 Co 0.1 Mn0.1 O2 and LLZTO powder were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet, and 10 mg of CuI ion donor material was evenly placed on the surface of the solid positive electrode. The mixture was kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into a 9.5 mm diameter disc and placed on the other side of the solid electrolyte sheet. The mixture was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as f4.

[0148] 5. Weigh 100 mg of LLZTO powder and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte powder sheet. Place the solid electrolyte powder sheet in a muffle furnace and calcine at 950 °C for 8 h. After cooling to room temperature with the furnace, obtain a solid oxide electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2 and LLZTO powder were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet, and 10 mg of CuCl ion donor material was evenly placed on the surface of the solid positive electrode. The mixture was kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into a 9.5 mm diameter disc and placed on the other side of the solid electrolyte sheet. The mixture was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as f5.

[0149] 6. Weigh 100 mg of LLZTO powder and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte powder sheet. Place the solid electrolyte powder sheet in a muffle furnace and calcine at 950 °C for 8 h. After cooling to room temperature with the furnace, obtain a solid oxide electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2 and LLZTO powder were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the solid electrolyte sheet, and 10 mg of Ag2S ion donor material was evenly placed on the surface of the solid positive electrode. The mixture was kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into a 9.5 mm diameter disc and placed on the other side of the solid electrolyte sheet. The mixture was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as f6.

[0150] 7. Weigh 100 mg of LLZTO powder and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte powder sheet. Place the solid electrolyte powder sheet in a muffle furnace and calcine at 950 °C for 8 h. After cooling to room temperature with the furnace, obtain a solid oxide electrolyte sheet. LiNi0.8 Co 0.1 Mn 0.1 O2 and LLZTO powder were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet, and 10 mg of AgCl ion donor material was evenly placed on the surface of the solid positive electrode. The mixture was kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into a 9.5 mm diameter disc and placed on the other side of the solid electrolyte sheet. The mixture was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as f7.

[0151] 8. Weigh 100 mg of LLZTO powder and place it in a 10 mm diameter PTFE sleeve. Maintain a pressure of 360 MPa for 10 min to obtain a solid electrolyte powder sheet. Place the solid electrolyte powder sheet in a muffle furnace and calcine at 950 °C for 8 h. After cooling to room temperature with the furnace, obtain a solid oxide electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2 and LLZTO powder were mixed evenly in a mortar at a mass ratio of 7:3 to form a composite positive electrode. 10 mg of the composite positive electrode was weighed and placed on one side of the solid electrolyte sheet, and 10 mg of AgBr ion donor material was weighed and evenly placed on the surface of the solid positive electrode. The mixture was kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into a 9.5 mm diameter disc and placed on the other side of the solid electrolyte sheet. The mixture was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as f8.

[0152] Battery types f1-f8 were cycled once at 60℃ with a current of 0.2mA within a voltage range of 2.7V to 4.3V. After the cycle, the batteries were disassembled for characterization, and the cross-sectional observations are shown below.

[0153] Table 6

[0154] As can be seen from the results in Table 6, in the solid-state battery of Example 6, the positive electrode active material is LiNi. 0.8 Co 0.1 Mn 0.1The O2 content was [missing information], and the solid electrolyte was LLZTO. In sample f1, no ion donor material was applied to the surface of the solid-state battery composite cathode. No ion migration paths were observed using energy-dispersive scanning electron microscopy (SEM-EDS). This is because lithium-ion migration paths in oxide solid-state batteries cannot be observed using SEM-EDS, thus making it impossible to observe the ion migration of each component in the solid-state battery. In samples f2-f8, ion donor materials were applied to the surface of the solid-state battery composite cathode using a pressurized method. These ion donor materials were copper powder, Cu2S, CuI, CuCl, Ag2S, AgCl, and AgBr, respectively. Ion migration paths were clearly observed under SEM-EDS in all samples, proving that this method is applicable to oxide solid electrolyte systems.

[0155] Example 7

[0156] All-solid-state lithium batteries, hybrid solid-liquid lithium batteries, all-solid-state sodium batteries, and hybrid solid-liquid sodium batteries

[0157] This embodiment uses Cu₂S as the ion donor material to illustrate the role of metal element ions (with Cu₂S as the ion donor). + (For example) The ion donor material Cu2S can migrate in all-solid-state lithium batteries, hybrid solid-liquid lithium batteries, all-solid-state sodium batteries, and hybrid solid-liquid sodium batteries, leaving migration paths after migration to trace ion pathways in solid-state batteries. This proves that the method can effectively trace ion pathways in hybrid solid-liquid lithium batteries, all-solid-state lithium batteries, hybrid solid-liquid sodium batteries, and all-solid-state sodium batteries. After preparing the battery in the following manner, the ion donor material Cu2S is uniformly covered on the surface of the solid positive electrode, the solid-state battery is assembled, and the battery is characterized after cycling.

[0158] 1. Weigh 100mg LGPS (Li 10 GeP2S 12 A sulfide solid electrolyte was placed in a 10 mm diameter PTFE sleeve and held at a pressure of 360 MPa for 10 minutes to obtain a solid electrolyte sheet. LiNi 0.8 Co 0.1 Mn 0.1 O2, LGPS, and Super P were mixed evenly in a mortar at a mass ratio of 7:3:1 to form a composite positive electrode. 10 mg of this mixture was placed on one side of the electrolyte sheet and kept under a pressure of 360 MPa for 10 min. 10 mg of Cu2S was then evenly placed on the surface of the solid positive electrode and kept under a pressure of 360 MPa for 10 min. A 50 μm thick lithium metal foil was cut into 9.5 mm diameter discs and placed on the other side of the electrolyte sheet. The mixture was kept under a pressure of 120 MPa for 5 min. The resulting battery is denoted as g1.

[0159] 2. LiNi 0.8 Co0.1 Mn 0.1 O2, LATP, Super P, and Cu2S were ground and dispersed in a mortar in a mass ratio of 7:3:1:1. PVDF adhesive and NMP solvent were added and stirred thoroughly to ensure uniform dispersion. The mixture was then added to a mixing tank and stirred again. The composite positive electrode slurry was then uniformly coated onto the surface of aluminum foil and dried in a 60°C oven for 6 hours. The dried composite positive electrode sheet was punched into a 12mm diameter disc and placed in a vacuum oven at 120°C for 6 hours. After the temperature dropped to room temperature, the electrode sheet was quickly transferred to an argon-filled glove box for storage. A battery was assembled using a LATP electrolyte-modified separator, a lithium metal anode, and this positive electrode sheet. Commercial lithium battery electrolyte was added dropwise to obtain a hybrid solid-liquid lithium battery, denoted as g2.

[0160] 3. Weigh 100 mg of Na3PS4 and place it in a 10 mm diameter PTFE sleeve. Maintain the mixture at 360 MPa for 10 min to obtain a solid electrolyte sheet. Mix Na3V2(PO4)3, Na3PS4, Super P, and Cu2S in a mortar at a mass ratio of 7:3:1:1 to obtain a composite positive electrode. Weigh 10 mg of this mixture and place it on one side of the electrolyte sheet. Maintain the mixture at 360 MPa for 10 min. Cut a 50 μm thick sodium foil into a 9.5 mm diameter disc and place it on the other side of the electrolyte sheet. Maintain the mixture at 120 MPa for 5 min. The resulting battery is denoted as g3.

[0161] 4. Na3V2(PO4)3, β-Al2O3, Super P, and Cu2S were ground and dispersed in a mortar at a mass ratio of 7:3:1:1. PVDF adhesive and NMP solvent were added and stirred thoroughly to ensure uniform dispersion. The mixture was then added to a mixing tank and stirred again. The composite positive electrode slurry was then uniformly coated onto the surface of aluminum foil and dried in a 60℃ oven for 6 hours. The dried composite positive electrode sheet was punched into a 12mm diameter disc and placed in a vacuum oven at 120℃ for 6 hours. After the temperature dropped to room temperature, the electrode sheet was quickly transferred to an argon-filled glove box for storage. A battery was assembled using a β-Al2O3 electrolyte-modified separator, a hard carbon negative electrode, and this positive electrode sheet. Commercial sodium battery electrolyte was added to the battery to obtain a hybrid solid-liquid sodium battery, denoted as g4.

[0162] Batteries g1-g2 were cycled once at 60°C with a current of 0.2mA within a voltage range of 2.7V to 4.3V. Batteries g3-g4 were cycled once at 60°C with a current of 0.2mA within a voltage range of 2.2V to 3.8V. After the cycling was completed, the batteries were disassembled and characterized. The cross-sectional observations of the batteries are shown below.

[0163] Table 7

[0164] As shown in Table 7, in Example 7, Cu2S ion donor material was applied to the cathode surfaces of all-solid-state lithium batteries, hybrid solid-liquid lithium batteries, all-solid-state sodium batteries, and hybrid solid-liquid sodium batteries in samples g1-g4 using a pressurized method. Ion migration paths were clearly observed under energy-dispersive scanning electron microscopy (SEM-EDS). The viewing window size for samples g1-g2 was 1 mm × 1 mm, and the viewing window size for samples g3-g4 was 200 μm × 200 μm.

[0165] It can be seen that when Cu2S is used as an ion donor material in lithium batteries (all-solid-state or hybrid solid-liquid lithium batteries), its corresponding viewing window range is the largest, allowing observation of ion migration paths in the positive electrode, electrolyte, and negative electrode of the lithium battery. When Cu2S is used as an ion donor material in sodium batteries (all-solid-state or hybrid solid-liquid sodium batteries), its corresponding viewing window range is smaller than that of lithium batteries, but it can still observe ion paths in the positive electrode and electrolyte of sodium batteries. This is because the radius of cuprous ions is very close to that of lithium ions, but the radius of cuprous ions is smaller than that of sodium ions. Therefore, the migration ability of cuprous ions in solid-state lithium batteries is stronger than that in solid-state sodium batteries. In the current embodiment of this invention, the thickness of the solid-state battery positive electrode is less than 100 μm. Therefore, in this method, a viewing window of 200 μm × 200 μm can meet the characterization requirements of the positive electrode and electrolyte in solid-state sodium batteries.

[0166] Figure 8 shows the SEM-EDS energy dispersive spectroscopy (EDS) images of the ion pathways in the positive electrode of sample g3 after battery charging. Figure 8(a) shows the SEM images of the positive electrode and electrolyte, as well as the EDS image of the Na distribution. Figures 8(b) and (c) show the EDS images of the Cu and S (representing Na3PS4 electrolyte) distributions. Before charging, copper was only distributed in the positive electrode layer of the solid sodium battery. After charging, Cu, like Na, entered the solid sodium electrolyte, indicating that cuprous ions have similar migration capabilities to sodium ions, passing through the positive electrode layer and entering the solid sodium electrolyte layer. By characterizing the cuprous ion pathway, the migration pathway of sodium ions can be obtained, proving that the present invention is also applicable to solid sodium batteries.

Claims

1. A method for tracing the migration paths of migrating ions in a solid-state battery, comprising the following steps: (1) Add an ion donor material to a solid-state battery and then charge and discharge the solid-state battery; wherein the solid-state battery contains migrating ions, the ion donor material is used to provide exogenous ions, the exogenous ions have the same valence state and similar ionic radius as the migrating ions, and the atomic number is higher than that of the migrating ions; (2) The solid-state battery that has completed the charge-discharge cycle is characterized and analyzed to determine the migration path of the exogenous ions and to use it as the migration path of the migrating ions in the solid-state battery.

2. The method according to claim 1, wherein, The difference in ionic radius between the migrated ion and the exogenous ion is less than or equal to 50 pm.

3. The method according to claim 2, wherein, The difference in ionic radius between the migrated ion and the exogenous ion is less than or equal to 20 pm.

4. The method according to claim 1, wherein, The ion donor material is selected from one or more of elemental substances of Group 1 and / or compounds containing Group 1 elements.

5. The method according to claim 4, wherein, The first subgroup element is copper and / or silver.

6. The method according to claim 1, wherein, The ion donor material is selected from one or more of elemental copper, copper nitride, copper oxide, cuprous oxide, copper fluoride, copper phosphide, cuprous phosphide, copper sulfide, cuprous sulfide, copper chloride, cuprous chloride, copper sulfate, copper selenide, cuprous selenide, cuprous iodide, elemental silver, silver oxide, silver fluoride, silver sulfide, silver chloride, silver arsenide, silver selenide, silver bromide, and silver iodide.

7. The method according to claim 1, wherein, The exogenous ions are copper ions and / or silver ions; Preferably, the exogenous ions are selected from Cu. + Cu 2+ and Ag + One or more of them.

8. The method according to claim 1, wherein, The solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte, wherein the positive electrode comprises a positive electrode material, and the addition of the ion donor material to the solid-state battery in step (1) is performed by a method comprising the following steps: The ion donor material is disposed on the surface of a solid electrolyte; and / or The ion donor material is disposed on the surface of the positive electrode of a solid-state battery; and / or The ion donor material is added to the cathode material of a solid-state battery.

9. The method according to claim 1, wherein, The solid-state battery is selected from one or more of hybrid solid-liquid batteries, quasi-solid-state batteries, and all-solid-state batteries; Preferably, the solid-state battery is a solid-state lithium battery and / or a solid-state sodium battery.

10. The method according to claim 1, wherein, The characterization analysis includes one or more of SEM-EDS, SIMS, XPS, CT, and Auger.

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