All-solid-state battery thin-layer electrode device for multi-mode in-situ interface research and application of all-solid-state battery thin-layer electrode device

Abstract

The invention relates to an all-solid-state battery thin-layer electrode device for multi-mode in-situ interface research. The all-solid-state battery thin-layer electrode device comprises the following components: a solid electrolyte substrate; the functional thin layer is arranged on the surface of the solid electrolyte substrate; the functional thin layer has conductivity; the functionalized thin layer allows a detection signal of an in-situ characterization technology to effectively penetrate or be reflected from the surface of the functionalized thin layer; the in-situ characterization techniques include atomic force microscopes, optical microscopes, and Raman spectroscopy, X-ray photoelectron spectroscopy, infrared spectroscopy, or X-ray diffraction. The invention provides a universal thin-layer electrode design and system and a thin-layer electrode in-situ imaging and spectroscopic characterization method for all-solid-state battery interface reaction. The objective of the invention is to expose a solid electrolyte-electrode interface reaction process which is difficult to observe in an effective detection range of various characterization technologies so as to realize real-time and in-situ visualization and accurate analysis of a dynamic evolution process of an internal interface of an all-solid-state battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of electrochemistry and advanced characterization technology, and specifically discloses a thin-layer electrode device for multi-mode in-situ interface research of a full-solid-state battery and application thereof. BACKGROUND

[0002] Full-solid-state batteries are considered as the ideal choice for the next generation of energy storage devices due to their high safety and high energy density. However, the commercialization process of full-solid-state batteries is seriously restricted by solid-solid interface problems, including but not limited to interface side reactions, lithium dendrite growth, contact failure, and space charge layer effects. A deep understanding of the dynamic process and micro mechanism of the interface reaction is the key to developing high-performance and long-life full-solid-state batteries.

[0003] Currently, the core technical bottleneck of full-solid-state battery research is that the key electrochemical processes that determine the performance mainly occur in the solid-solid interface embedded by the electrode and the electrolyte body phase. The interface dynamically evolves under the working state of the battery, but it is difficult to be observed in real time and in situ, especially to realize in-situ characterization with high spatial resolution. The detection signal of the mainstream high-resolution technology (such as atomic force microscope, microscopic Raman spectrum, etc.) cannot effectively penetrate or analyze the hidden interface blocked and disturbed by the bulk phase material, resulting in the lack of key micro dynamic information such as interface reaction process, byproduct spatial distribution, lithium dendrite nucleation and spread, etc. Therefore, the interface research still largely relies on indirect speculation and non-in-situ static analysis. Therefore, the existing technology lacks an interface research strategy compatible with multiple in-situ characterization technologies, which makes it difficult to reveal the interface dynamic evolution rule of the full-solid-state battery in the working state in real time and intuitively at the nanometer or micrometer scale, seriously hindering the accurate understanding of the interface failure mechanism and the development of high-efficiency interface scheme. The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a universal thin-layer electrode design and in-situ characterization method, which provides a key technical solution for multi-mode in-situ research of the interface reaction of the full-solid-state battery.

[0004] There is no such device for observing and detecting the interface inside the full-solid-state battery in the prior art. The multi-mode in-situ interface research full-solid-state battery thin-layer electrode assembly provided by the present application can directly expose the "hidden" solid-solid interface reaction process in the traditional battery to the effective detection range of multiple characterization technologies, thereby realizing real-time, in-situ, multi-modal visualization observation and accurate analysis of the dynamic evolution process of the full-solid-state battery interface. The implementation of the present application can directly capture the key dynamic processes such as interface side reaction, lithium deposition / dissolution behavior, interface phase evolution, crack initiation and expansion under the working state of the battery, which provides indispensable in-situ experimental data and observation basis for deeply understanding the interface failure mechanism, establishing a battery life prediction model based on micro mechanism, and guiding the system design and manufacturing process optimization of high-reliability and long-life full-solid-state batteries. SUMMARY

[0005] To solve the problem that the existing technology is difficult to perform high spatial resolution in-situ dynamic characterization on the solid-solid interface embedded in the all-solid-state battery, the application provides a universal thin-layer electrode design, a system and a method for in-situ imaging and spectroscopy characterization of thin-layer electrode interface reaction of an all-solid-state battery. The purpose is to expose the solid electrolyte-electrode interface reaction process which is difficult to observe to the effective detection range of various characterization technologies, so as to realize real-time and in-situ visualization and accurate analysis of the dynamic evolution process of the solid electrolyte internal interface. To achieve the above purpose, the application adopts the following technical solutions:

[0006] In a first aspect, the application provides a thin-layer electrode device for multi-mode in-situ interface research of an all-solid-state battery, comprising the following components: a solid electrolyte substrate; a functionalized thin layer arranged on the surface of the solid electrolyte substrate; the functionalized thin layer has electrical conductivity; the functionalized thin layer allows the detection signal of in-situ characterization technology to effectively penetrate or reflect from its surface; the in-situ characterization technology includes atomic force microscopy, optical microscopy, and Raman spectroscopy, X-ray photoelectron spectroscopy, infrared spectroscopy or X-ray diffraction.

[0007] The thickness of the functionalized thin layer is a key control parameter. The thickness is a core factor for determining whether the detection signal can penetrate or whether a high spatial resolution can be obtained. The thickness of the thin layer needs to be controlled at the nanometer to micrometer level. The specific value depends on the thickness that the reaction can pass through. For negative electrode reactions such as metal lithium deposition, the thin layer thickness should be able to effectively penetrate the metal lithium, and is usually 5 nm to 500 nm, preferably 10 nm to 200 nm, and more preferably 20 nm to 100 nm. For positive electrode reactions, the thickness should be the thickness that lithium ions and electrons can penetrate, and is usually 5 nm to 50 μm, preferably 100 nm to 30 μm, and more preferably 500 nm to 20 μm. The reason why the thickness of the positive electrode system is generally larger than that of the negative electrode is that the particle size of the positive electrode active material is usually hundreds of nanometers to several micrometers. If the thickness of the thin layer is too small, a continuous ion-electron conduction network cannot be formed, and it is difficult to drive the complete bulk reaction.

[0008] The functionalized thin layer is a continuous and dense film, and the surface roughness Ra of the functionalized thin layer is less than 10% of the thickness; the functionalized thin layer and the solid electrolyte substrate are attached by physical cold pressing or thermal evaporation, etc., to enhance the adhesion.

[0009] Further, the solid electrolyte substrate is a dense sheet or a porous support. Further, the solid electrolyte substrate is selected from LISICON-type solid electrolytes and derivatives thereof, including Li2GeS3, Li4GeS4, Li2ZnGeS4, Li 4- 2x Zn xGeS4(wherein 0≤x≤1), Li5GaS4, Li 4+x+y (Ge 1-y-x Ga x )S4(wherein 0≤x≤0.2, 0≤y≤1), Li 10 GeP2S 12-x-y O x F y (wherein 0≤x≤1, 0≤y≤1), Li 2+2x Zn 1-x GeO4(wherein 0≤x≤1), Li 3+z X z Y 1-z O4(Y=P, As or V; X=Si, Ge or Ti, 0≤z≤1), Li 11-x M 2-x P 1+x S 12 (M=Ge, Sn or Si, 0≤x≤2), for example Li 10 GeP2S 12 ; or the solid electrolyte is selected from halide-type inorganic solid electrolytes and derivatives thereof, or sulfide-type inorganic solid electrolytes and derivatives thereof, the halide-type solid electrolyte having a composition of Li 3-x M 1-x Zr x X6(M=Y, Er or In; X=Cl or Br, 1≧x≧0), the sulfide-type solid electrolyte having a composition of xLi2S-(100-x)P2S5(wherein x is 50-87.5), Li6PS5X (X=Cl, Br or I), for example Li3PS4, Li7P3S 11 , Li6PS5Cl; or the solid electrolyte is selected from at least one of polymers and derivatives thereof, polyethylene oxide, polycarbonate, polysiloxane and copolymers or crosslinked networks thereof.

[0010] Further, the functional thin layer is of two types:

[0011] (a) for the negative electrode, the functional thin layer has a thickness of 5 nm to 500 nm, preferably 10 nm to 200 nm, more preferably 20 nm to 100 nm, such as 50-80 m. When the functional thin layer is used for negative electrode interface observation, its nanoscale thickness allows the probe or optical / spectral signals to directly perceive the changes in morphology and properties during the interface reactions (such as lithium deposition, dissolution and solid electrolyte interface film formation). When lithium deposition / dissolution is performed on the electrode, this layer provides an electron conductive path.

[0012] The material of the thin electron conductor layer is preferably one of the following materials:

[0013] (a1) Electron conductor materials capable of serving as lithium metal deposition substrate or capable of forming alloys with lithium, including but not limited to the following categories: metal materials: copper (Cu), nickel (Ni), platinum (Pt) and other inert metals, which can serve as stable deposition substrate; gold (Au), silver (Ag), tin (Sn), zinc (Zn), silicon (Si), aluminum (Al), magnesium (Mg), indium (In), germanium (Ge) and others, which can form alloys or intermetallic compounds with lithium;

[0014] (a2) Alloys and intermetallic compounds: including lithium alloy materials (such as lithium-tin alloy, lithium-silicon alloy, lithium-aluminum alloy, etc.; metal nitrides, metal carbides and other compounds with good electronic conductivity) or carbon-based materials (such as graphene, graphene-like carbon film, pyrolytic carbon film, carbon nanotube film), which have high conductivity and light weight characteristics;

[0015] (a3) Conductive oxides and other functional thin films: such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO) and other transparent conductive oxides, suitable for use with optical detection; metal nitrides (such as TiN) and other high-stability conductive thin films;

[0016] (b) For the positive electrode, the functional thin layer has a thickness of 5 nm to 50 μm, preferably 100 nm to 30 μm, and more preferably 500 nm to 20 μm; the functional thin layer is composed of positive electrode active material, conductive agent and solid-state electrolyte material, and is used for positive electrode interface research. Its limited thickness ensures that the electrochemical reaction process (such as phase change, volume change, byproduct generation, etc.) on the surface or near the surface of the electrode can be effectively detected. The mass ratio of positive electrode active material: conductive agent: solid-state electrolyte is 7-9: 2-3: 0.5-1.

[0017] The positive electrode active material is selected from at least one of sulfur, lithium sulfide, transition metal oxide, iron fluoride, lithium peroxide, ternary material, lithium cobaltate, lithium iron phosphate; the conductive agent is selected from at least one of carbon nanotube, Ketjen black, Super P, acetylene black; the solid-state electrolyte can be selected from at least one of the following categories: LISICON type and its derivatives, such as Li2GeS3, Li4GeS4, Li2ZnGeS4, Li 4-2x Zn x GeS4(0≤x≤1), Li5GaS4, Li 4+x+y (Ge 1-y-x Ga x )S4(0≤x≤0.2, 0≤y≤1), Li 10 GeP2S 12-x-y O x F y (0≤x≤1, 0≤y≤1), Li 2+2x Zn 1-xGeO4(0≤x≤1), Li 3+z X z Y 1-z O4(Y=P, As or V; X=Si, Ge or Ti, 0≤z≤1), Li 11-x M 2-x P 1+x S 12 (M=Ge, Sn or Si, 0≤x≤2), such as Li 10 GeP2S 12 ; halide-type inorganic solid electrolytes and their derivatives, with a composition of Li 3-x M 1-x Zr x X6(M=Y, Er or In; X=Cl or Br, 0≤x≤1); sulfide-type inorganic solid electrolytes and their derivatives, such as xLi2S·(100–x)P2S5(50≤x≤87.5), Li6PS5X(X=Cl, Br or I), Li3PS4, Li7P3S 11 , Li6PS5Cl; polymer-based solid electrolytes: composed of a polymer matrix, a lithium salt, and optionally a plasticizer or inorganic filler. Among them, the polymer matrix is selected from at least one of polyethylene oxide, polycarbonate, polysiloxane, and copolymers or crosslinked networks thereof; the lithium salt is selected from at least one of lithium bis(trifluoromethylsulfonyl)imide, lithium bisfluorosulfonylimide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium difluoro oxalate borate, lithium trifluoromethylsulfonate.

[0018] Further, the functional thin layer is composed with the solid-state electrolyte substrate by one of physical vapor deposition, thermal evaporation or physical pressing, and the thickness of the functional thin layer is adjusted by:

[0019] If the functional thin layer is prepared by physical vapor deposition: the thickness of the thin layer is adjusted by controlling the deposition time, sputtering / evaporation power, substrate temperature, and real-time calibration using an active film thickness monitoring feedback system.

[0020] If the functional thin layer is prepared by thermal evaporation: the thickness of the thin layer is adjusted by adjusting the evaporation source temperature, deposition time, substrate distance, and real-time monitoring of the deposition rate using a quartz crystal microbalance.

[0021] If the functional thin layer is prepared by physical pressing: the thickness of the thin layer is adjusted by adjusting the applied pressure (0.1 MPa to 500 MPa), pressing time, and powder filling amount.

[0022] The second object of the present application is to provide an in-situ characterization system for all-solid-state batteries, comprising the following components:

[0023] The above-mentioned all-solid-state battery thin-layer electrode device for multi-mode in-situ interface research: as the observed core component, the functionalized thin-layer surface faces the observation window;

[0024] Counter electrode: forms an electrochemical pair with the functionalized thin layer in the thin-layer electrode assembly, and fills or directly contacts a solid-state electrolyte material between the two, forming a complete electrochemical loop; the counter electrode is selected from at least one of the following materials: 1, metal negative electrode: metal lithium foil; 2, lithium alloy negative electrode: lithium-tin alloy, lithium-silicon alloy, lithium-magnesium alloy, lithium-aluminum alloy, etc.; 3, lithium-containing metal compound negative electrode: lithium titanate, lithium oxide, lithium sulfide, etc.; 4, silicon-based / alloy-based negative electrode: elemental silicon, silicon oxide, silicon-carbon composite material, etc.; 5, carbon-based negative electrode: lithiated graphite, hard carbon, soft carbon, etc.; 6, other metal negative electrode: metals or their composite materials that can form alloys with lithium, such as tin, antimony, aluminum, etc.

[0025] Model battery device: provided with a sealed cavity for accommodating the battery assembly; equipped with mechanical fasteners (such as screws) for applying controllable and uniform mechanical pressure to the battery assembly; and provided with at least one transparent observation window (diameter 1-10 mm, preferably 4-6 mm) to expose the functionalized thin-layer surface to external signal detection;

[0026] Signal detection unit: fixed or adjustably arranged outside the observation window, with its detection end aligned with the functionalized thin-layer surface through the observation window, to realize real-time and in-situ monitoring of its morphology, mechanics, electricity or chemistry; the cavity material of the model battery device is polyether ether ketone, stainless steel or engineering plastic to meet the requirements of insulation, corrosion resistance or high strength;

[0027] Preferably, the signal detection unit is selected from at least one of an atomic force microscope, an optical microscope or a spectrometer (such as a Raman spectrometer, an infrared spectrometer). When an atomic force microscope is used, its working mode includes one or more of contact mode, tapping mode, conductive atomic force microscope, Kelvin probe force microscope, electrochemical strain microscope;

[0028] Electrochemical test unit: connected to the thin-layer electrode assembly and the counter electrode through wires, for applying electrical signals such as potential and current to the battery, and controlling its charge and discharge state or conducting impedance test, synchronized with the signal detection process.

[0029] In a third aspect, the present application provides a thin-layer electrode in-situ imaging and spectroscopic characterization method for interface reaction of all-solid-state batteries using the above-mentioned in-situ characterization system for all-solid-state batteries, comprising the following steps:

[0030] (S1) Battery assembly and pressure application: stack the functionalized thin layer, solid-state electrolyte sheet, and counter electrode in the cavity of the model battery device in sequence to form a battery sandwich structure;

[0031] Controllable pressure is applied to the stacked structure using mechanical fasteners, with the pressure range being 0.01 MPa to 100 MPa, preferably 1 MPa to 20 MPa, to ensure uniform and stable physical and electrochemical contact between the layers.

[0032] (S2) Observation area alignment: Fix the assembled and pressurized model battery device on the stage or positioning platform of the signal detection unit; observe by scanning probe or laser positioning to make the detection area of ​​the signal detection unit accurately aligned with the surface area to be tested of the functionalized thin layer;

[0033] (S3) Synchronous electrochemical-in-situ signal acquisition: Connect the working electrode lead and the reference / counter electrode lead of the electrochemical testing unit to the functionalized thin film and the counter electrode, respectively; set the electrochemical testing signal, including but not limited to: constant current charge-discharge, cyclic voltammetry or electrochemical impedance spectroscopy; while applying the electrochemical signal, start the signal detection unit to perform in-situ scanning or spectral acquisition on the surface of the functionalized thin film; record and correlate the electrochemical signal (current, voltage, impedance) with the morphological, mechanical, electrical or chemical spectroscopic data acquired by the signal detection unit in real time to obtain dynamic evolution information of the interfacial reaction process.

[0034] Optionally, the method further includes step (S4): after the test, the pressure is released, the battery assembly is disassembled, and the functionalized thin layer is characterized in non-in-situ to supplement the verification.

[0035] Compared with the prior art, the present invention has the following significant advantages:

[0036] High versatility: Through precise thin-layer design, the embedded solid-solid interface is "exposed", making it compatible with a variety of high spatial resolution characterization methods such as atomic force microscopy, optical microscopy, and various spectroscopic techniques, realizing a leap from single technology to multi-technology combination.

[0037] High fidelity and in-situ accuracy: Under real-world battery conditions with controlled pressure, real-time, in-situ visualization of interfacial dynamic processes (such as lithium dendrite growth, cathode phase transition, and interfacial side reactions) at the nanometer to micrometer scale is achieved, resulting in more authentic and direct data.

[0038] Revealing the microscopic mechanism of interfacial reactions: This invention provides an experimental platform and technical solutions for revealing key scientific issues in all-solid-state batteries, such as the relationship between lithium deposition overpotential and morphology, interfacial ion transport mechanism, space charge layer effect, and interfacial side reaction pathway. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the all-solid-state battery thin-film electrode design for in-situ imaging / spectroscopy research according to the present invention.

[0040] Figure 2 Figure 1 is an in-situ atomic force microscope image during the process of thin layer Ag electrode plating lithium obtained in Example 1.

[0041] Figure 3 Figure 2 is an atomic force microscope image of the surface morphology of the electrode before and after lithium deposition in Comparative Example 1.

[0042] Figure 4 Figure 3 is an in-situ atomic force image obtained in Example 2.

[0043] Figure 5 Figure 4 is a surface scanning electron microscope image before and after the positive electrode reaction in Comparative Example 2. DETAILED DESCRIPTION

[0044] The present application is further described in conjunction with the following specific examples, but the present application is not limited to the following examples. In the following examples, the experimental methods described are conventional methods, unless otherwise specified; and the reagents and materials described are commercially available, unless otherwise specified. The following specific example is provided to help understand the thin layer electrode design strategy described in the present application.

[0045] Example 1:

[0046] In this example, the preparation of a thin layer electrode assembly for in-situ AFM study of the negative electrode interface, the battery assembly and testing process are specifically described.

[0047] 1. Preparation of thin layer electrode assembly and battery:

[0048] First, in an argon atmosphere glove box (water and oxygen content ≤0.1 ppm), 90 mg of sulfide solid-state electrolyte Li6PS5Cl powder was weighed and placed in a mold. It was cold-pressed into a dense disc with a diameter of 10 mm under a pressure of 350 MPa as a solid-state electrolyte substrate.

[0049] Subsequently, a layer of metal silver (Ag) with a thickness of about 80 nm was deposited on one side surface of the solid-state electrolyte substrate using a thermal evaporation method. This Ag layer constitutes the ultra-thin electronic conductor layer described in the claims.

[0050] Finally, a metal lithium sheet with a diameter of 10 mm was attached to the other side of the solid-state electrolyte substrate as a counter electrode, thereby completing the assembly of the thin layer electrode assembly and battery containing a (Li | Li6PS5Cl | Ag) sandwich structure.

[0051] 2. In-situ characterization and testing:

[0052] The assembled battery was placed in a model battery device. The device body was a polyether ether ketone sealed cavity, and a circular observation window with a diameter of 6 mm was provided at the top of the cavity; a positioning groove was provided in the cavity for fixing the stacking structure of the solid electrolyte sheet, the thin-layer electrode assembly and the counter electrode. A pressure of 1 MPa was applied along the stacking direction by four evenly distributed screw fasteners on the side wall of the cavity to ensure good interface contact between the components. Subsequently, the model battery device was fixed as a whole on the sample table of an atomic force microscope, and the sample table was adjusted so that the probe of the atomic force microscope was vertically aligned and contacted with the Ag layer on the surface of the thin-layer electrode assembly through the observation window, and in-situ scanning imaging was performed.

[0053] The entire device was connected with an electrochemical test unit (blue battery test system). First, the battery was controlled to perform constant current discharge at a current density of 0.1 mA / cm². During this process, lithium metal would be dissolved from the side of the counter electrode and pass through the solid electrolyte in the form of Li + and finally undergo reduction reaction and deposition on the surface of the ultra-thin Ag electronic conductor layer.

[0054] Figure 2 is an in-situ atomic force microscope image obtained during the process of plating lithium on the thin-layer Ag electrode of Example 1. Before lithiation, the surface of the Ag layer was composed of particles with a particle size of about 20 nm; as the plating proceeded, a large number of spherical deposits with a diameter of about 3 μm were observed on the surface, which directly corresponded to the uniform and large-scale nucleation and growth process of metal lithium on the modified interface.

[0055] Through in-situ and real-time observation by an atomic force microscope (as a signal detection unit), the dynamic process of nucleation, growth and morphology evolution of metal lithium on the surface of the Ag layer can be clearly captured, and the lithium deposition behavior of the negative electrode interface is directly revealed. It is found at the nanoscale that the particle expansion and fusion of the Ag layer during the initial lithiation process further promotes the uniform nucleation of a large amount of metal lithium, and guides the lithium to be deposited in a spherical shape in a large amount and uniformly, thereby significantly improving the uniformity of the interface reaction. The obtained dynamic morphology evolution image and electrochemical data provide direct experimental evidence for in-depth understanding of the deposition mechanism of lithium.

[0056] Comparative Example 1:

[0057] In-situ characterization attempt based on thick powder electrode

[0058] 1. Preparation of the battery:

[0059] In order to form a clear contrast with the ultra-thin electronic conductor layer design of the present application, a micron-thick powder electrode was used in this comparative example. The specific steps are as follows: in an argon gas glove box (water and oxygen content ≤0.1 ppm), a Li6PS5Cl solid electrolyte substrate (diameter 10 mm) was prepared according to the method of Example 1.

[0060] Subsequently, instead of using thermal evaporation method to prepare ultra-thin Ag layer, about 100 mg of micron-sized silver powder (particle size 1-5 μm) was weighed and poured into the mold, and then directly pressed onto the surface of the solid electrolyte substrate under a pressure of 350 MPa to form a dense Ag powder electrode layer with a thickness of several hundred microns.

[0061] Finally, a piece of metallic lithium was attached to the other side of the solid electrolyte substrate as the counter electrode, and the battery assembly containing the structure (Li | Li6PS5Cl | thick Ag powder electrode) was completed.

[0062] 2. In-situ characterization attempts and results:

[0063] The assembled battery was placed in the same model battery device as in Example 1, and an attempt was made to perform in-situ atomic force microscopy testing. The battery was controlled to discharge at a constant current of 0.1 mA / cm², while the atomic force microscope probe was attempted to scan the surface of the thick Ag powder electrode.

[0064] Figure 3 are the atomic force microscope images of the surface morphology of the electrode before and after lithium deposition in Comparative Example 1. It can be seen that during the entire discharge process, the atomic force microscope cannot obtain stable and meaningful surface morphology images. Since the Ag powder electrode surface itself is composed of micron-sized particles, the initial roughness is large, and the probe cannot stably track the surface. In addition, even if lithium metal is deposited at the interface between the Ag powder particles or with the electrolyte, this reaction area is physically blocked and wrapped by the thick and rough Ag powder particles above, making it impossible for the AFM probe to touch and detect the true interface reaction process. After the test, the battery was disassembled to confirm that an electrochemical reaction had occurred, but the key electrochemical interface was completely "embedded" and could not be observed in-situ.

[0065] Example 2:

[0066] 1. Preparation of thin-layer electrode assembly and battery:

[0067] First, in an argon atmosphere glove box (water and oxygen content ≤0.1 ppm), a model composite positive electrode layer was prepared. Lithium peroxide (Li2O2) positive electrode active material, conductive agent (acetylene black), and sulfide solid electrolyte Li6PS5Cl powder were uniformly mixed in a mass ratio of 70:20:10. About 10 mg of the mixture was placed on the surface of a Li6PS5Cl solid electrolyte substrate (diameter 10 mm, prepared by the same method as in Example 1) that had been pre-pressed with 90 mg of Li6PS5Cl at 250 MPa.

[0068] Subsequently, the positive electrode mixture and the electrolyte substrate were pressed together at a pressure of 100 MPa to form a dense model composite positive electrode layer with a thickness of about 10 μm.

[0069] Finally, a piece of lithium metal with a diameter of 10 mm was attached to the other side of the solid-state electrolyte substrate as the counter electrode, thereby completing the assembly of the thin-layer electrode assembly and battery containing the sandwich structure of (positive electrode | Li6PS5Cl | Li).

[0070] 2. In-situ characterization and testing:

[0071] The assembled battery was placed in the in-situ characterization system for all-solid-state batteries described in Example 1, and a constant pressure of 1 MPa was applied through the evenly distributed bolts on the sidewall of the model battery device to ensure uniform and stable physical-electrochemical interface contact between the solid-state electrolyte, the model composite positive electrode layer, and the counter electrode. Subsequently, the battery device was connected to the electrochemical test unit (blue battery test system), the test parameters were set, and the battery was controlled to charge at a current density of 0.05 C (based on the theoretical capacity of the positive electrode active material).

[0072] During the charging process, an atomic force microscope was simultaneously started as a signal detection unit to continuously and in-situ image the surface morphology of the model composite positive electrode layer through the observation window on the top of the model battery device. This system can directly observe and record the dynamic structural evolution of the positive electrode material during charging and discharging.

[0073] Figure 4 is the in-situ atomic force microscope image obtained in Example 2. The experimental results show that at the initial stage of charging, lithium peroxide (Li2O2) undergoes electrochemical decomposition with obvious volume shrinkage; at the same time, the adjacent solid-state electrolyte region undergoes local expansion due to oxidation reaction. These two opposite volume changes are clearly captured by the atomic force microscope, directly revealing the competitive reaction path and strain evolution process at the positive electrode-electrolyte interface. This result provides direct nanoscale experimental evidence for a deep understanding of the interface reaction mechanism, byproduct formation, and volume mismatch problems in solid-state lithium-oxygen batteries.

[0074] Comparative Example 2

[0075] 1. Battery preparation and processing:

[0076] A (positive electrode | Li6PS5Cl | Li) battery was prepared exactly as in Example 2. After discharging the battery to a specific capacity at a rate of 0.05 C, the test was stopped.

[0077] The cell was removed from the test equipment and carefully disassembled in an argon atmosphere to remove the solid-state electrolyte interface tab in contact with the positive electrode. After cleaning the sample, it was transferred to a scanning electron microscope (SEM) for observation and analysis.

[0078] Figure 5 The surface scanning electron microscope images before and after the positive electrode reaction in Comparative Example 2 are shown. Before the reaction and after the reaction is completed, the positive electrode surface is always composed of a large number of particles accumulated, and no obvious overall morphology evolution or structure reorganization is observed.

[0079] SEM is difficult to distinguish whether there are reaction products at the interface, and it is also difficult to determine when these products are formed, in what dynamic process, and to accurately correlate with specific potential / capacity points on the charge-discharge curve. There is a risk of exposure to air during sample preparation and transfer, which may introduce artifacts and cannot truly reflect the interface chemistry under working conditions.

[0080] This comparative example shows that the ex situ characterization method can only provide isolated and static snapshots before and after the reaction, and cannot capture the continuous process of the interface dynamic evolution, so it is difficult to reveal the reaction mechanism in depth.

Claims

1. A thin-film electrode device for all-solid-state batteries used in multi-mode in-situ interface research, characterized in that, Includes the following components: solid electrolyte substrate; A functionalized thin layer is disposed on the surface of the solid electrolyte substrate; the functionalized thin layer is conductive; the functionalized thin layer allows the detection signals of in-situ characterization techniques to effectively penetrate or be reflected from its surface; The in-situ characterization techniques include atomic force microscopy, optical microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, infrared spectroscopy, or X-ray diffraction; for the negative electrode reaction mode, the thickness of the functionalized thin layer is 5 nm to 500 nm; for the positive electrode reaction mode, the thickness of the functionalized thin layer is 5 nm to 50 μm.

2. The all-solid-state battery thin-film electrode device according to claim 1, characterized in that, For the negative electrode reaction mode, the thickness of the functionalized thin layer is 5 nm to 500 nm, preferably 10 nm to 200 nm; for the positive electrode reaction mode, the thickness of the functionalized thin layer is 5 nm to 50 μm, preferably 100 nm to 30 μm.

3. The all-solid-state battery thin-film electrode device according to claim 1, characterized in that, The solid electrolyte substrate is a dense sheet or porous support; furthermore, the solid electrolyte substrate is selected from LISICON-type solid electrolytes and their derivatives, including Li₂GeS₃, Li₄GeS₄, Li₂ZnGeS₄, and Li 4-2x Zn x GeS4 (where 0 ≤ x ≤ 1), Li5GaS4, Li 4+x+y (Ge 1-y-x Ga x S4 (where 0 ≤ x ≤ 0.2, 0 ≤ y ≤ 1), Li 10 GeP2S 12-x-y O x F y (where 0≤x≤1, 0≤y≤1), Li 2+2x Zn 1-x GeO4 (where 0 ≤ x ≤ 1), Li 3+z X z Y 1-z O4 (Y = P, As or V; X = Si, Ge or Ti, 0 ≤ z ≤ 1), Li 11- x M 2-x P 1+x S 12 (M = Ge, Sn or Si, 0 ≤ x ≤ 2), for example, Li 10 GeP2S 12 Alternatively, the solid electrolyte may be selected from halide-type inorganic solid electrolytes and their derivatives, or sulfide-type inorganic solid electrolytes and their derivatives, wherein the halide-type solid electrolyte has a composition of Li. 3-x M 1-x Zr x X6 (M = Y, Er or In; X = Cl or Br, 1 ≧ x ≧ 0), the sulfide-type solid electrolyte has the composition xLi2S·(100–x)P2S5 (where x is 50-87.5), Li6PS5X (X = Cl, Br or I), for example Li3PS4, Li7P3S 11 Li6PS5Cl; or the solid electrolyte is selected from at least one of polymers and their derivatives, polyethylene oxide, polycarbonate, polysiloxane and their copolymers or cross-linked networks.

4. The all-solid-state battery thin-film electrode device according to claim 1, characterized in that, For the negative electrode reaction mode, the materials for the functionalized thin layer are as follows: (a1) Electronic conductor materials that can serve as lithium metal deposition substrates or can form alloys with lithium, including but not limited to the following categories: metallic materials: inert metals such as copper (Cu), nickel (Ni), and platinum (Pt), which can serve as stable deposition substrates; gold (Au), silver (Ag), tin (Sn), zinc (Zn), silicon (Si), aluminum (Al), magnesium (Mg), indium (In), and germanium (Ge); (a2) Alloys and intermetallic compounds: including lithium alloy materials (such as lithium-tin alloy, lithium-silicon alloy, lithium-aluminum alloy, etc.; metal nitrides, metal carbides, etc., compounds with good electronic conductivity) or carbon-based materials (such as graphene, graphene-like carbon films, pyrolytic carbon films, carbon nanotube films). (a3) Conductive oxides and other functional thin films: including indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and metal nitrides (such as TiN).

5. The all-solid-state battery thin-film electrode device according to claim 1, characterized in that, For the positive electrode, the functionalized thin layer is composed of a positive electrode active material, a conductive agent and a solid electrolyte material; preferably, the mass ratio of positive electrode active material: conductive agent: solid electrolyte is 7-9:2-3:0.5-1.

6. The all-solid-state battery thin-film electrode device according to claim 5, characterized in that, The positive electrode active material is selected from at least one of sulfur, lithium sulfide, transition metal oxides, iron fluoride, lithium peroxide, ternary materials, lithium cobalt oxide, and lithium iron phosphate; the conductive agent is selected from at least one of carbon nanotubes, Ketjen black, Super P, and acetylene black; the solid electrolyte can be selected from at least one of the following categories: LISICON type and its derivatives, such as Li2GeS3, Li4GeS4, Li2ZnGeS4, Li 4-2x Zn x GeS4 (0≤x≤1), Li5GaS4, Li 4+x+y (Ge 1-y-x Ga x )S4 (0≤x≤0.2, 0≤y≤1), Li 10 GeP2S 12-x-y O x F y (0≤x≤1, 0≤y≤1), Li 2+2x Zn 1-x GeO4 (0≤x≤1), Li 3+z X z Y 1-z O4 (Y = P, As, or V; X = Si, Ge, or Ti, 0 ≤ z ≤ 1), Li 11-x M 2-x P 1+x S 12 (M = Ge, Sn, or Si, 0 ≤ x ≤ 2), such as Li 10 GeP2S 12 Halogenated inorganic solid electrolytes and their derivatives, with a composition of Li 3-x M 1-x Zr x X6 (M = Y, Er, or In; X = Cl or Br, 0 ≤ x ≤ 1); sulfide-type inorganic solid electrolytes and their derivatives, such as xLi2S·(100–x)P2S5 (50 ≤ x ≤ 87.5), Li6PS5X (X = Cl, Br, or I), Li3PS4, Li7P3S 11 Li6PS5Cl; Polymer-based solid electrolyte: composed of a polymer matrix, a lithium salt, and optionally a plasticizer or inorganic filler; wherein the polymer matrix is ​​selected from at least one of polyethylene oxide, polycarbonate, polysiloxane and their copolymers or cross-linked networks; the lithium salt is selected from at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium difluorooxalateborate, and lithium trifluoromethanesulfonate.

7. The all-solid-state battery thin-film electrode device according to claim 1, characterized in that, The functionalized thin layers are all composited with the solid electrolyte substrate by one of the following methods: physical vapor deposition, thermal evaporation, or physical pressing.

8. An in-situ characterization system for all-solid-state batteries, characterized in that, Includes the following components: The all-solid-state battery thin-film electrode device for multi-mode in-situ interface research as described in any one of claims 1-7 For the electrodes, Model battery assembly: It has a sealed cavity for housing the battery assembly; it is equipped with mechanical fasteners that apply controllable and uniform mechanical pressure to the battery assembly, and has at least one observation window; A signal detection unit that is fixedly or adjustablely installed on the outside of the observation window; An electrochemical testing unit connected to a thin-film electrode assembly and a counter electrode via wires; Preferably, the signal detection unit is selected from at least one of an atomic force microscope, an optical microscope, or a spectrometer (such as a Raman spectrometer or an infrared spectrometer). When an atomic force microscope is used, its operating modes include one or more of contact mode, tapping mode, conductive atomic force microscope, Kelvin probe force microscope, and electrochemical strain microscope. Preferably, the diameter of the observation window is 1-10 mm, more preferably 4-6 mm.

9. A method for in-situ imaging and spectroscopic characterization of thin-layer electrodes for interfacial reactions in all-solid-state batteries using the all-solid-state battery in-situ characterization system of claim 8, characterized in that, Includes the following steps: (S1) Battery assembly and pressure application: The functionalized thin layer, the solid electrolyte sheet, and the counter electrode are stacked sequentially in the cavity of the model battery device to form a battery sandwich structure. (S2) Observation area alignment: Fix the assembled and pressurized model battery device on the stage or positioning platform of the signal detection unit; observe by scanning probe or laser positioning to make the detection area of ​​the signal detection unit accurately aligned with the surface area to be tested of the functionalized thin layer; (S3) Synchronous Electrochemical-In-Situ Signal Acquisition: Connect the working electrode lead and the reference / counter electrode lead of the electrochemical testing unit to the functionalized thin film and the counter electrode, respectively; set the electrochemical testing signal, including but not limited to: constant current charge-discharge, cyclic voltammetry or electrochemical impedance spectroscopy; while applying the electrochemical signal, start the signal detection unit to perform in-situ scanning or spectral acquisition on the surface of the functionalized thin film; record and correlate the electrochemical signal (current, voltage, impedance) with the morphological, mechanical, electrical or chemical spectroscopic data acquired by the signal detection unit in real time to obtain dynamic evolution information of the interfacial reaction process; Preferably, in step (S1), a controllable pressure is applied to the stacked structure by mechanical fasteners, with the pressure range being 0.01 MPa to 100 MPa, preferably 1 MPa to 20 MPa, to ensure that uniform and stable physical and electrochemical contact is formed between the layers. Preferably, the method further includes step (S4): after the test, the pressure is released, the battery assembly is disassembled, and the functionalized thin layer is characterized in non-in-situ to supplement the verification.

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