A method for preparing an XRD test sample and an XRD test method

Abstract

The application relates to the technical field of battery performance detection, in particular to a preparation method of an XRD test sample and an XRD test method.The preparation method comprises the following steps: disassembling a battery, taking out an electrode sheet, and performing cleaning and drying treatment on the electrode sheet; adopting an adhesive piece to paste one side of the electrode sheet provided with an active material layer, then removing the electrode sheet to obtain an XRD test sample; and adopting the adhesive piece to paste the active material layer on the electrode sheet, so that the active substance of the active material layer is transferred from the electrode sheet to the adhesive piece during pasting; and the XRD test sample is obtained after the electrode sheet is removed; the XRD test sample is subjected to XRD test, the process operation is simple and fast, the problem of current collector metal signal interference is solved, and in addition, the XRD spectrum obtained by the method has high peak strength of characteristic peaks and high signal-to-noise ratio.

Description

Technical Field

[0001] This application relates to the field of battery performance testing technology, specifically to a method for preparing an XRD test sample and an XRD testing method. Background Technology

[0002] In lithium-ion batteries, the crystal structure changes of battery materials during charge and discharge have always been a key focus. Characterizing the structure of battery materials effectively reveals the principles of battery reactions, enables failure analysis, and facilitates in-depth investigations into material mechanisms. X-ray diffraction (XRD) is one of the commonly used methods for characterizing the crystal structure of battery materials. Since changes in crystal structure are closely related to battery cycle performance, XRD testing of electrode sheets after charge and discharge is frequently used to evaluate the cycle performance of battery materials, significantly shortening evaluation time and reducing testing costs. XRD testing of electrode sheets after charge and discharge can also be used to predict the pre-lithiation amount and / or pre-lithiation capacity of pre-lithiated batteries; the method is simple, fast, and highly accurate.

[0003] Currently, there are two main approaches to characterize the crystal structure of electrodes after charge-discharge cycles: in-situ and non-in-situ. In-situ characterization allows for real-time monitoring of material changes; however, it places specific demands on equipment and battery structure, resulting in extremely high testing costs. Furthermore, in-situ characterization suffers from significant signal interference from the battery casing and current collectors, making it difficult to focus on the true material composition. Non-in-situ characterization, on the other hand, involves disassembling the battery after the reaction and performing XRD tests on the charged-discharge electrodes. However, the problem of signal interference from current collectors still exists. Summary of the Invention

[0004] This application provides a method for preparing an XRD test sample and an XRD testing method to solve the problem of current collector metal signal interference in the existing XRD testing technology.

[0005] In a first aspect, this application provides a method for preparing an XRD test sample, the method comprising the following steps:

[0006] Step S1: Disassemble the battery, remove the electrode plates, and clean and dry the electrode plates.

[0007] Step S2: Use an adhesive to attach the electrode sheet to one side where the active material layer is located, and then remove the electrode sheet to obtain the XRD test sample.

[0008] In one alternative embodiment, the adhesive is double-sided tape.

[0009] In one alternative embodiment, the battery is a battery that has undergone charging or discharging treatment.

[0010] In one optional embodiment, the peel strength of the adhesive is 5N / 25mm to 15N / 25mm.

[0011] In one optional embodiment, before removing the electrode sheet, a step of rolling the electrode sheet with the adhesive attached is included. Optionally, during rolling, the pressure roller abuts against the electrode sheet with the adhesive attached.

[0012] In one optional embodiment, the number of roller pressing cycles is 1 to 5, and the pressure is 5-60 MPa.

[0013] In one optional embodiment, the electrode sheet is a positive electrode sheet or a negative electrode sheet; the positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector; the negative electrode sheet includes a positive current collector and a negative active material layer disposed on at least one surface of the negative current collector.

[0014] Optionally, the positive electrode active material layer comprises lithium-ion battery positive electrode active material and / or sodium-ion battery positive electrode active material;

[0015] Optionally, the negative electrode active material layer comprises one or more of graphite, hard carbon, silicon-based materials, and tin-based materials.

[0016] In one optional embodiment, in step S1, the electrode sheet is cleaned with an organic solvent; optionally, the organic solvent is one or more of ethanol, isopropanol, acetone, and dimethyl carbonate; more preferably, it is acetone.

[0017] In one optional embodiment, the drying is vacuum drying; optionally, the drying temperature is 80–120°C, and the time is 2–6 hours.

[0018] Secondly, this application provides an XRD testing method, including the preparation method of any of the XRD test samples described above, and also includes the step of performing XRD testing on the XRD test samples.

[0019] Furthermore, during the XRD test, the target material is a Cu target or a Mo target, the voltage is 30-50kV, the current is 7-8mA, the step size is 0.01-0.02°, the step time is 28-32s, the divergence slit is 1 / 4-1°, the scanning range is 5-120°, and the scanning speed is 1-2° / min.

[0020] The technical solution of this application has the following advantages:

[0021] 1. The method for preparing XRD test samples provided in this application includes the following steps: disassembling the battery, removing the electrode sheet, and cleaning and drying the electrode sheet; using an adhesive to attach the side of the electrode sheet where the active material layer is disposed, and then removing the electrode sheet to obtain the XRD test sample. By using an adhesive to attach the active material layer on the electrode sheet, the active material in the active material layer is transferred from the electrode sheet to the adhesive during the attachment process. After removing the electrode sheet, the XRD test sample is obtained. XRD testing of the XRD test sample is not only simple and quick, but also solves the problem of current collector metal signal interference. In addition, the XRD spectrum obtained by this method has high peak intensity and high signal-to-noise ratio.

[0022] 2. The method for preparing XRD test samples provided in this application, by controlling the peel strength of the adhesive to be 5N / 25mm to 15N / 25mm, can better peel the active material from the original electrode sheet without peeling off the current collector.

[0023] 3. The method for preparing XRD test samples provided in this application includes a step of rolling the electrode sheet with the adhesive attached before removing the electrode sheet, so as to make the adhesion between the active material and the adhesive more firm, increase the degree of peeling of the active material from the electrode sheet, increase the active material on the surface of the adhesive, thereby improving the signal intensity of the effective substance and further reducing the signal-to-noise ratio. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 These are the XRD curves obtained after XRD testing in Examples 1 and 2;

[0026] Figure 2 These are the XRD curves obtained after XRD testing in Examples 1-2 and Comparative Examples 1-2;

[0027] Figure 3 It is the XRD curve obtained after XRD testing of copper foil. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification of this application are intended to cover non-exclusive inclusion.

[0030] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0031] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0032] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0034] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more (including two groups), and "multiple pieces" refers to two or more (including two pieces).

[0035] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0036] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0037] Characterizing electrode sheets after charge and discharge using in-situ methods places special requirements on equipment and battery structure, resulting in extremely high testing costs. Furthermore, these methods are susceptible to significant signal interference from the battery casing and current collectors. Non-in-situ characterization methods, on the other hand, still suffer from current collector signal interference issues, and scraping off the electrode powder introduces complex processing procedures.

[0038] To address the problems existing in the aforementioned related technologies, according to a first aspect of this application, a method for preparing an XRD test sample is provided, the preparation method comprising the following steps:

[0039] Step S1: Disassemble the battery, remove the electrode plates, and clean and dry the electrode plates.

[0040] Step S2: Use an adhesive to attach the electrode sheet to one side where the active material layer is located, and then remove the electrode sheet to obtain the XRD test sample.

[0041] This application uses an adhesive to attach the active material layer on the electrode sheet. During the attachment process, the active material in the active material layer is transferred from the electrode sheet to the adhesive. After removing the electrode sheet, an XRD test sample is obtained. XRD testing of the XRD test sample is not only simple and quick, but also solves the problem of metal signal interference from the current collector. In addition, the XRD spectrum obtained by this method has high peak intensity and high signal-to-noise ratio.

[0042] In one alternative embodiment, the adhesive is double-sided tape.

[0043] In one alternative embodiment, the battery is a battery that has undergone charging and / or discharging treatment.

[0044] In one optional embodiment, the peel strength of the adhesive is 5 N / 25 mm to 15 N / 25 mm. Too low a peel strength will prevent the material from being peeled off the electrode, while too high a peel strength may damage the material structure. Controlling the peel strength within this range ensures the transfer of active material from the active material layer while avoiding damage to the active material layer or even peeling off the current collector. Examples include 5 N / 25 mm, 10 N / 25 mm, or 15 N / 25 mm. The peel strength of the adhesive is determined according to the national standard GB / T 2792-2014 "Test Method for Peel Strength of Adhesive Tapes".

[0045] In one optional embodiment, before removing the electrode sheet, a step of rolling the electrode sheet with the adhesive attached is included. Optionally, during rolling, the pressure roller abuts against the electrode sheet with the adhesive attached.

[0046] In one optional embodiment, the number of rolling passes is 1 to 5, and the pressure is 5-60 MPa. For example, the number of rolling passes can be 1, 3, or 5. The pressure can be 5 MPa, 10 MPa, 15 MPa, 30 MPa, or 60 MPa. Controlling the number of rolling passes and the pressure within the above range promotes better adhesion between the active material and the adhesive, thereby improving the signal strength of the active material and further reducing the signal-to-noise ratio.

[0047] In one optional embodiment, the electrode sheet is a positive electrode sheet or a negative electrode sheet; the positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector; the negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector.

[0048] In some embodiments, the positive electrode active material layer comprises lithium-ion battery positive electrode active material and / or sodium-ion battery positive electrode active material.

[0049] The specific type of positive electrode active material is not limited and can be selected according to requirements. For example, positive electrode active materials may include, but are not limited to, lithium iron phosphate (LiFePO4), lithium manganese phosphate (LiMnPO4), lithium cobalt phosphate (LiCoPO4), iron pyrophosphate (Li2FeP2O7), lithium cobalt oxide (LiCoO2), spinel-type lithium manganese oxide (LiMn2O4), and spinel-type lithium nickel manganese oxide (LiNi). 0.5 Mn 1.5O4), layered lithium manganate (LiMnO2), lithium nickelate (LiNiO2), lithium niobate (LiNbO2), lithium ferrite (LiFeO2), lithium manganate (LiMgO2), lithium calcium oxide (LiCaO2), lithium copper oxide (LiCuO2), lithium zinc oxide (LiZnO2), lithium molybdate (LiMoO2), lithium tantalate (LiTaO2), lithium tungstate (LiWO2), lithium nickel cobalt aluminum oxide (LiNi x Co y Al 1-x-y O2, 0 < x < 1, 0 < y < 1, 0 < x + y < 1, for example LiNi 0.8 Co 0.15 Al 0.05 O2), lithium nickel cobalt manganese oxide (LiNi x Co y Mn 1-x-y O2, 0 < x < 1, 0 < y < 1, 0 < x + y < 1, for example LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, etc.), lithium-rich materials (such as lithium-rich nickel cobalt manganese oxide), manganese dioxide (MnO2), vanadium oxide, sulfur oxide, silicate oxide, and at least one of their respective modified compounds. These materials can be used alone or in combination of two or more.

[0050] In this application, the positive electrode material can also be a compound that can reversibly intercalate and deintercalate Na+. As an example, the positive electrode active material includes transition metal oxides, polyanion compounds, Prussian blue analogs, etc.

[0051] In some embodiments, the positive electrode active material is a transition metal oxide. As an example, Na x MO2 or Na y M2O4 (where M is a transition metal, 0 ≤ x ≤ 1, 0 ≤ y ≤ 2) can be mentioned for sodium-containing composite oxides, spinel-like oxides, layered metal chalcogenides, olivine structures, etc. For example, sodium cobalt oxides such as NaCoO2, sodium manganese oxides such as NaMn2O4, sodium nickel oxides such as NaNiO2, Na 4 / 3 Ti 5 / 3Sodium titanium oxides such as O4, sodium manganese nickel composite oxides, sodium manganese nickel cobalt composite oxides; materials with olivine-type crystal structures such as NaMPO4 (M=Fe, Mn, Ni), etc.

[0052] In some embodiments, the positive electrode active material may optionally be a layered or spinel-like sodium-containing composite oxide, such as NaCoO2, NaMn2O4, NaNiO2, or NaNi 1 / 2 Mn 1 / 2 Sodium-manganese-nickel composite oxides, represented by O2, etc., with NaNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, NaNi 0.6 Mn 0.2 Co 0.2 Sodium-manganese-nickel-cobalt composite oxides, represented by O2, or NaNi 1-x-y- z Co x Al y Mg z Sodium-containing composite oxides such as O2 (where 0≤x≤1, 0≤y≤0.1, 0≤z≤0.1, 0≤1-xyz≤1). Furthermore, sodium-containing composite oxides in which a portion of the constituent elements of the aforementioned sodium-containing composite oxides are replaced by additive elements such as Ge, Ti, Zr, Mg, Al, Mo, and Sn are also included within the scope of this application.

[0053] In some embodiments, the positive electrode active material is optionally a polyanionic compound. As an example, the polyanionic compound may be a compound containing sodium ions, transition metal ions, or a tetrahedral (YO4) structure. n- A class of compounds with anionic units. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si; n represents (YO4). n- The valence state. Polyanionic compounds can also have sodium ions, transition metal ions, or tetrahedral (YO4) ions. n- A class of compounds containing anionic units and halide anions. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si, and n represents (YO4). n- The valence state; the halogen can be at least one of F, Cl, or Br. Polyanionic compounds can also have sodium ions, tetrahedral (YO4) valence states. n- Anionic unit, polyhedral unit (ZO) y ) m+And a class of compounds with optional halide anions. Y can be at least one of P, S, and Si, and n represents (YO4). n- The valence state; Z represents a transition metal, which can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; m represents (ZO) y ) m+ The valence state; the halogen can be at least one of F, Cl, and Br. Examples of polyanionic compounds include NaFePO4, Na3V2(PO4)3, NaM'PO4F (M' is one or more of V, Fe, Mn, and Ni), and Na3(VO4)2(PO4)3. y )2(PO4)2F 3-2y At least one of (0≤y≤1).

[0054] In some embodiments, the positive electrode active material is optionally a Prussian blue analogue. As an example, Prussian blue compounds may contain sodium ions, transition metal ions, and cyanide ions (CN). - A class of compounds. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Prussian blue compounds include, for example, Na. a Me b Me' c (CN)6, wherein Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0 < a ≤ 2, 0 < b < 1, 0 < c < 1.

[0055] The modified compounds for the above-mentioned positive electrode active materials can be modified by doping, surface coating, or both doping and coating.

[0056] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0057] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0058] In some embodiments, the positive electrode active material layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0059] In some embodiments, the binder may optionally comprise 0.1-3.5% of the total weight of the positive electrode active material layer, optionally 0.5-2.5%.

[0060] In some embodiments, the positive electrode active material layer may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0061] In some embodiments, the conductive agent may optionally account for 0.05-5% of the total weight of the positive electrode active material layer, and optionally 0.5-3%.

[0062] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0063] In some embodiments, the negative electrode active material layer may comprise a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: graphite, hard carbon, silicon-based materials, tin-based materials, etc. The graphite may be selected from artificial graphite and / or natural graphite. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0064] In some embodiments, the negative electrode active material layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0065] In some embodiments, the negative electrode active material layer may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0066] In some embodiments, the negative electrode active material layer may also optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0067] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0068] In one optional embodiment, in step S1, the electrode sheet is cleaned with an organic solvent; optionally, the organic solvent is one or more of ethanol, isopropanol, acetone, and dimethyl carbonate; more preferably, it is acetone.

[0069] In one optional embodiment, the drying is vacuum drying; optionally, the drying temperature is 80–120°C, and the time is 2–6 hours. For example, the drying temperature can be 80°C, 100°C, or 120°C. The time can be 2 hours, 4 hours, or 6 hours.

[0070] Secondly, this application provides an XRD testing method, including the preparation method of any of the XRD test samples described above, and also includes the step of performing XRD testing on the XRD test samples.

[0071] Furthermore, during the XRD test, the target material is a Cu target or a Mo target, the voltage is 30-50kV, the current is 7-8mA, the step size is 0.01-0.02°, the step time is 28-32s, the divergence slit is 1 / 4-1°, the scanning range is 5-120°, and the scanning speed is 1-2° / min.

[0072] For example, the voltage can be 30kV, 40kV or 50kV, the current can be 7mA, 7.5mA or 8mA, the step size can be 0.01°, 0.015° or 0.02°, the step time can be 28s, 30s or 32s, the divergence slit can be 1°, 1 / 4°, 1 / 3° or 1 / 2°, and the scanning speed can be 1° / min, 1.5° / min or 2° / min.

[0073] The battery described in this application also includes a separator and an electrolyte.

[0074] As for the aforementioned separator, this application does not have any particular limitations. Any known porous structure separator with electrochemical and mechanical stability can be selected according to actual needs. For example, it can be a single-layer or multi-layer film containing one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.

[0075] As for the electrolyte mentioned above, this application does not have any particular restrictions, and conventional electrolytes can be selected according to actual needs, generally including electrolyte salts and solvents.

[0076] As an example, the electrolyte sodium salt includes at least one of sodium hexafluorophosphate, sodium difluorooxalate borate, sodium tetrafluoroborate, sodium dioxalate borate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethanesulfonate, and sodium bis(trifluoromethanesulfonyl)imide.

[0077] As an example, the solvent may include one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), and fluoroethylene carbonate (FEC).

[0078] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0079] In some embodiments, the battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0080] In some implementations, the battery's outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The battery's outer packaging can also be a soft pack, such as a pouch. The soft pack can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0081] This application does not impose any particular restrictions on the shape of the battery; it can be cylindrical, square, or any other arbitrary shape.

[0082] In some implementations, the batteries can be assembled into battery modules, and the number of batteries contained in a battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0083] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0084] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0085] The test batteries in each embodiment and comparative example were prepared using either method one or method two as follows:

[0086] Method 1: Mix the negative electrode active material, conductive agent Super P, and binder SBR in a mass ratio of 8:1:1 to obtain a mixture. Add the mixture to water and mix thoroughly to prepare a negative electrode slurry (solid content of 31.5%). The negative electrode slurry is then prepared at a concentration of 1.2 mg / cm³. 2 A single-sided surface density uniform coating is applied to the negative electrode current collector copper foil, followed by drying, cold pressing, and die cutting to form the negative electrode sheet for the lithium-ion battery. Lithium salt (LiPF6) is dissolved in a mixed solvent of EC, EMC, and DMC in a volume ratio of 1:1:1 to obtain an electrolyte with a lithium salt concentration of 12.5 wt%. The aforementioned negative electrode sheet, PP / PE separator, lithium sheet, and electrolyte are assembled into a CR2032 coin cell. The prepared test battery is charged to obtain a fully charged battery, i.e., a state of charge (SOC) of 100%.

[0087] Method 2: Mix the positive electrode active material, conductive agent Super P, and binder PVDF in a mass ratio of 92:4:4 to obtain a uniform mixture. Add the mixture to the solvent NMP to prepare a positive electrode slurry (solid content of 6.25%). The positive electrode slurry is then prepared at a concentration of 17 mg / cm³. 2 A single-sided surface density uniform coating is applied to the positive electrode current collector aluminum foil, followed by drying, cold pressing, and die cutting to form the positive electrode sheet for lithium-ion batteries. Lithium salt (LiPF6) is dissolved in a mixed solvent of EC, EMC, and DMC in a volume ratio of 1:1:1 to obtain an electrolyte with a lithium salt concentration of 12.5 wt%. The positive electrode sheet, PP / PE separator, lithium sheet, and electrolyte are assembled into a CR2032 coin cell. The prepared test battery is charged to obtain a fully charged battery, i.e., a state of charge (SOC) of 100%.

[0088] Example 1

[0089] This embodiment provides a method for preparing an XRD test sample and an XRD testing method, including the following steps:

[0090] The test battery prepared by Method 1 above, wherein the negative electrode active material used in the preparation of the test battery is SiO, was disassembled in a glove box filled with an inert atmosphere to obtain the negative electrode sheet. The negative electrode sheet was repeatedly cleaned three times with acetone and then dried in a vacuum oven at 105℃ for 4 hours. Double-sided adhesive tape with a peel strength of 5N / 25mm was pressed onto the surface of the negative electrode sheet, and it was repeatedly rolled three times using a roller press at a pressure of 20MPa. The negative electrode sheet was in contact with the upper and lower rollers (i.e., the gap between the negative electrode sheet and the upper and lower rollers was 0mm). The tape was removed, and the side without material was pasted onto the sample stage for XRD testing.

[0091] The test parameters for the X-ray diffractometer analysis of the sample are as follows: target material is Cu target, voltage is 40kV, current is 7.5mA, scanning range is set to 2θ=15-80°, step time is 29s, step size is set to 0.01°, divergence slit is set to 1°, and scanning speed is 1.5° / min.

[0092] Example 2

[0093] This embodiment provides a method for preparing an XRD test sample and performing XRD testing, including the following steps:

[0094] The test battery prepared by Method 1 above, wherein the negative electrode active material used in the preparation of the test battery is SiO, was disassembled in a glove box filled with an inert atmosphere to obtain the negative electrode sheet. The negative electrode sheet was repeatedly cleaned three times with isoacetone and then dried in a vacuum oven at 80℃ for 2 hours. Double-sided adhesive tape with a peel strength of 15N / 25mm was pressed onto the surface of the electrode sheet, and it was repeatedly rolled three times with a pressure of 20MPa, ensuring the negative electrode sheet was in contact with the upper and lower rollers (i.e., the gap between the negative electrode sheet and the upper and lower rollers was 0mm). The tape was removed, and the side without material was adhered to the sample stage for XRD testing.

[0095] The test parameters for the X-ray diffractometer analysis of the sample are as follows: target material is Cu target, voltage is 40kV, current is 7.5mA, scanning range is set to 2θ=15-80°, step time is 29s, step size is set to 0.01°, divergence slit is set to 1°, and scanning speed is 1.5° / min.

[0096] The method for preparing the battery under test in this embodiment is the same as in Embodiment 1.

[0097] Example 3

[0098] This embodiment provides a method for preparing an XRD test sample and performing XRD testing, including the following steps:

[0099] The test battery prepared by method two above is used, wherein the molecular formula of the positive electrode active material used in the preparation of the test battery is as follows: Li(Ni) 0.8 Co 0.1 Mn 0.1 The positive electrode was obtained by disassembling the battery under test in a glove box filled with an inert atmosphere using O2. It was then repeatedly cleaned three times with dimethyl carbonate and dried in a vacuum oven at 120°C for 6 hours. Double-sided adhesive tape with a peel strength of 10 N / 25 mm was pressed onto the electrode surface and repeatedly rolled five times with a roller press at a pressure of 10 MPa, ensuring the positive electrode was in contact with the upper and lower rollers (i.e., the gap between the positive electrode and the upper and lower rollers was 0 mm). The tape was then removed, and the side without material was adhered to the sample stage for XRD testing.

[0100] The test parameters for the X-ray diffractometer analysis of the sample are as follows: target material is Cu target, voltage is 40kV, current is 7.5mA, scanning range is set to 2θ=15-80°, step time is 29s, step size is set to 0.01°, divergence slit is set to 1°, and scanning speed is 1.5° / min.

[0101] The method for preparing the battery under test in this embodiment is the same as in Embodiment 1.

[0102] Example 4

[0103] This embodiment provides a method for preparing an XRD test sample and conducting XRD testing, which is basically the same as in Embodiment 1, except that the test parameters of the X-ray diffractometer for analyzing the sample are different.

[0104] In this embodiment, the test parameters for the X-ray diffractometer to analyze the sample are as follows: the target material is Cu, the voltage is 50kV, the current is 7mA, the scanning range is set to 2θ=5-80°, the step time is 28s, the step size is set to 0.02, the divergence slit is set to 1 / 4°, and the scanning speed is 1° / min.

[0105] Example 5

[0106] This embodiment provides a method for preparing an XRD test sample and conducting XRD testing, which is basically the same as in Embodiment 1, except that the test parameters of the X-ray diffractometer for analyzing the sample are different.

[0107] In this embodiment, the test parameters for the X-ray diffractometer to analyze the sample are as follows: the target material is Cu, the voltage is 30kV, the current is 8mA, the scanning range is set to 2θ=5-120°, the step time is 32s, the step size is set to 0.015°, the divergence slit is set to 1 / 2°, and the scanning speed is 2° / min.

[0108] Example 6

[0109] This embodiment provides a method for preparing an XRD test sample and conducting XRD testing, which is basically the same as in Embodiment 1, except that the double-sided tape is removed without being rolled after being pressed.

[0110] Example 7

[0111] This embodiment provides a method for preparing an XRD test sample and conducting XRD testing, which is basically the same as in Embodiment 1, except that the number of rolling cycles is 1.

[0112] Example 8

[0113] This embodiment provides a method for preparing an XRD test sample and performing XRD testing, which is basically the same as in Embodiment 1, except that isoacetone is used instead of acetone during cleaning.

[0114] Example 9

[0115] This embodiment provides a method for preparing an XRD test sample and conducting XRD testing, which is basically the same as in Embodiment 3, except that the positive electrode active material used in the preparation of the battery under test in this embodiment is NaMn2O4.

[0116] Example 10

[0117] This embodiment provides a method for preparing an XRD test sample and conducting XRD testing, which is basically the same as in Embodiment 1, except that the negative electrode active material used in the preparation of the battery under test in this embodiment is graphite.

[0118] Comparative Example 1

[0119] This comparative example provides a method for preparing an XRD test sample and performing XRD testing, including the following steps:

[0120] The battery under test was disassembled in a glove box with an inert atmosphere to obtain the negative electrode sheet, which was then directly subjected to XRD testing.

[0121] The X-ray diffractometer was used to analyze the sample as in Example 1. The preparation method of the battery in this comparative example was the same as in Example 1.

[0122] Comparative Example 2

[0123] This comparative example provides a method for preparing an XRD test sample and performing XRD testing, including the following steps:

[0124] The negative electrode was obtained by disassembling the battery under test in a glove box filled with an inert atmosphere. It was repeatedly washed three times with acetone and then dried in a vacuum oven at 105°C for 4 hours. The dried negative electrode was then subjected to XRD testing. The X-ray diffractometer parameters for analyzing the sample were the same as in Example 1. The preparation method of the battery under test in this comparative example was the same as in Example 1.

[0125] Comparative Example 3

[0126] This comparative example provides a method for preparing an XRD test sample and performing XRD testing, including the following steps:

[0127] The positive electrode was obtained by disassembling the battery under test in a glove box filled with an inert atmosphere. It was then repeatedly washed three times with dimethyl carbonate and dried in a vacuum oven at 120°C for 6 hours. The dried positive electrode was then subjected to XRD testing. The X-ray diffractometer parameters for analyzing the sample were the same as in Example 3. The preparation method of the battery under test in this comparative example was the same as in Example 3.

[0128] The XRD test results of each embodiment and comparative example are shown in the table below.

[0129] Table 1 XRD Test Results

[0130] Peak intensity (cps) Are there any interfering peaks? Signal-to-noise ratio Example 1 8600 none 3.44 Example 2 6500 none 2.33 Example 3 12500 none 3.05 Example 4 8500 none 2.98 Example 5 7700 none 2.88 Example 6 5500 none 2.01 Example 7 6000 none 2.23 Example 8 8200 none 3.01 Example 9 13500 none 3.55 Example 10 12100 none 3.04 Comparative Example 1 3000 Copper interference peaks are present 1.50 Comparative Example 2 2100 Copper interference peaks are present 1.51 Comparative Example 3 5700 Aluminum interference peaks are present 1.55

[0131] Figure 3 The copper foil was tested and analyzed using a direct X-ray diffractometer, with the same test parameters as in Example 1. Figure 1-3 It can be seen that the XRD patterns obtained by the method in Comparative Examples 1-2 not only contain copper interference peaks, but also interfere with the characteristic peaks of the negative electrode active material (see...). Figure 2 The arrow indicates the position of the sample peak (which is close to the position of the interference peak). Moreover, the main sample characteristic peak has a low peak intensity and a low signal-to-noise ratio. The XRD pattern obtained by the method of Comparative Example 3 has aluminum interference peaks. However, the XRD pattern obtained by the method of each embodiment of the present invention not only has no interference peaks, but also the intensity of the sample peaks is significantly improved, and the signal-to-noise ratio is significantly increased.

[0132] Compared with Example 6, Example 1 improves the signal strength of the effective material and further reduces the signal-to-noise ratio by rolling the electrode sheet with the adhesive attached.

[0133] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A method for preparing an XRD test sample, characterized in that, The preparation method includes the following steps: Step S1: Disassemble the battery, remove the electrode plates, and clean and dry the electrode plates. Step S2: Use an adhesive to attach the side of the electrode sheet with the active material layer, and then remove the electrode sheet to obtain the XRD test sample.

2. The method for preparing XRD test samples according to claim 1, characterized in that, The adhesive is double-sided tape.

3. The method for preparing XRD test samples according to claim 1 or 2, characterized in that, The battery is a battery that has undergone charging or discharging treatment.

4. The method for preparing XRD test samples according to any one of claims 1-3, characterized in that, The peel strength of the adhesive is 5N / 25mm to 15N / 25mm.

5. The method for preparing XRD test samples according to any one of claims 1-4, characterized in that, Before removing the electrode sheet, the process includes a rolling step of pressing the electrode sheet with the adhesive attached. Optionally, during the rolling process, the pressure roller abuts against the electrode sheet with the adhesive attached.

6. The method for preparing XRD test samples according to claim 5, characterized in that, The number of roller pressing cycles is 1 to 5, and the pressure is 5-60 MPa.

7. The method for preparing XRD test samples according to any one of claims 1-6, characterized in that, The electrode sheet is a positive electrode sheet or a negative electrode sheet; the positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector; the negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector; Optionally, the positive electrode active material layer comprises lithium-ion battery positive electrode active material and / or sodium-ion battery positive electrode active material; Optionally, the negative electrode active material layer comprises one or more of graphite, hard carbon, silicon-based materials, and tin-based materials.

8. The method for preparing XRD test samples according to any one of claims 1-7, characterized in that, In step S1, the electrode sheet is cleaned using an organic solvent; optionally, the organic solvent is one or more of ethanol, isopropanol, acetone, and dimethyl carbonate; more preferably, it is acetone.

9. The method for preparing an XRD test sample according to any one of claims 1-8, characterized in that, The drying process is vacuum drying; optionally, the drying temperature is 80–120°C and the drying time is 2–6 hours.

10. An XRD testing method, characterized in that, The method for preparing an XRD test sample according to any one of claims 1-9 further includes the step of performing XRD testing on the XRD test sample.

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