Method and device for detecting sodium separation threshold value of sodium ion battery negative electrode material

Abstract

The invention provides a method and a device for detecting a sodium separation threshold value of a sodium ion battery negative electrode material, and belongs to the field of lithium ion batteries. The method for detecting the sodium separation threshold value of the battery negative electrode material comprises the following steps: assembling a negative electrode material to be detected into a half-battery system; discharging the half-cell system for multiple times by utilizing constant current; acquiring the voltage change of the half-cell system after each discharge; determining an internal resistance value change curve of the half-cell system in the whole discharge process based on the voltage change of the half-cell system after each discharge; and determining the sodium separation threshold value of the negative electrode material of the half-cell system based on the internal resistance value change curve. According to the invention, accurate determination of the sodium separation threshold value of the sodium ion battery negative electrode material can be realized.

Description

Technical Field

[0001] This disclosure relates to the field of sodium-ion battery technology, and specifically to a method and apparatus for detecting the sodium deposition threshold of sodium-ion battery negative electrode materials. Background Technology

[0002] Sodium-ion batteries are rechargeable batteries that primarily use sodium ions as charge carriers to move between the positive and negative electrodes to achieve the charging and discharging process. During the charging process of sodium-ion batteries, sodium deposition easily occurs in the negative electrode material.

[0003] However, existing methods for detecting sodium deposition in sodium-ion batteries are insufficient to accurately determine the sodium deposition threshold of the anode material itself. Summary of the Invention

[0004] The purpose of this disclosure is to provide a method, apparatus, device, and storage medium for accurately determining the sodium deposition threshold of sodium-ion battery anode materials.

[0005] To achieve the above objectives, in a first aspect, embodiments of this disclosure provide a method for detecting the sodium deposition threshold of a sodium-ion battery anode material, comprising: assembling the anode material to be tested into a half-cell system; discharging the half-cell system multiple times using a constant current; obtaining the voltage change of the half-cell system after each discharge; determining the internal resistance change curve of the half-cell system throughout the discharge process based on the voltage change of the half-cell system after each discharge; and determining the sodium deposition threshold of the anode material of the half-cell system based on the internal resistance change curve.

[0006] In some embodiments, obtaining the voltage change of the half-cell system after each discharge includes: when the amount of electricity released by the half-cell system during each discharge reaches a preset first electricity threshold, interrupting the discharge process and keeping the half-cell system in a static state for a preset first duration; and obtaining the voltage change of the half-cell system after each discharge within the first duration.

[0007] In some embodiments, the constant current is 0.1C to 5C, the first charge threshold is 0.1% SOC to 5% SOC, and the first duration is 1s to 5s.

[0008] In some embodiments, the constant current is 0.5C, the first charge threshold is 1% SOC, and the first duration is 3s.

[0009] In some embodiments, determining the internal resistance change curve of the half-cell system throughout the entire discharge process based on the voltage change of the half-cell system after each discharge includes: determining the internal resistance value of the half-cell system after each discharge based on the voltage change of the half-cell system after each discharge; and determining the internal resistance change curve of the half-cell system throughout the entire discharge process based on the internal resistance value of the half-cell system after each discharge.

[0010] In some embodiments, determining the sodium deposition threshold of the negative electrode material of the half-cell system based on the internal resistance change curve includes: determining the decay inflection point of the internal resistance change curve based on the internal resistance change curve; and determining the sodium deposition threshold of the negative electrode material of the half-cell system based on the decay inflection point, wherein the sodium deposition threshold is the amount of electricity cumulatively released by the half-cell system corresponding to the decay inflection point.

[0011] In some embodiments, determining the decay inflection point of the internal resistance change curve based on the internal resistance change curve includes: if the change trend of the internal resistance change curve is first decreasing, then leveling off, and then decreasing again, then the point of the second decrease is taken as the decay inflection point of the internal resistance change curve; if the change trend of the internal resistance change curve is first decreasing and then continuously decreasing, then the point of continuous decrease is taken as the decay inflection point of the internal resistance change curve.

[0012] In some embodiments, before discharging the half-cell system multiple times with a constant current, the method further includes: forming the half-cell system with a formation current, wherein the formation current is 0.01C to 0.1C.

[0013] In some embodiments, the half-cell system is a button cell half-cell system, and the negative electrode material is assembled into a half-cell system in the form of a negative electrode sheet. The half-cell system is assembled according to the following components: negative electrode shell, sodium sheet, separator, negative electrode sheet, gasket, spring sheet, and positive electrode shell.

[0014] Secondly, embodiments of this disclosure provide a detection device for the sodium deposition threshold of a sodium-ion battery anode material, comprising: an assembly unit for assembling the anode material to be tested into a half-cell system; a discharge testing unit for discharging the half-cell system multiple times using a constant current; a voltage acquisition unit for acquiring the voltage change of the half-cell system after each discharge; a determination unit for determining the internal resistance change curve of the half-cell system throughout the discharge process based on the voltage change of the half-cell system after each discharge; and a device for determining the sodium deposition threshold of the anode material of the half-cell system based on the internal resistance change curve.

[0015] Through the above technical solution, the method for detecting the sodium deposition threshold of sodium-ion battery anode materials provided in this disclosure embodiment can achieve accurate determination of the sodium deposition threshold of sodium-ion battery anode materials.

[0016] Other features and advantages of the embodiments disclosed herein will be described in detail in the following detailed description section. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the embodiments of this disclosure and form part of the specification. They are used together with the following detailed description to explain the embodiments of this disclosure, but do not constitute a limitation thereof. In the drawings:

[0018] Figure 1 This is a flowchart provided in Example 1 of the method for detecting the sodium deposition threshold of sodium-ion battery anode materials disclosed herein;

[0019] Figure 2 This is a flowchart provided in Example 2 of the method for detecting the sodium deposition threshold of sodium-ion battery anode materials according to this disclosure;

[0020] Figure 3 This is a flowchart illustrating the process of determining the internal resistance change curve of a half-cell system throughout the discharge process, as provided in Embodiment 2 of this disclosure.

[0021] Figure 4 This is a flowchart provided in Example 3 of the method for detecting the sodium deposition threshold of sodium-ion battery anode materials according to this disclosure;

[0022] Figure 5 This is a flowchart illustrating the process of determining the attenuation inflection point of the internal resistance change curve according to Embodiment 3 of this disclosure;

[0023] Figure 6 This is a schematic diagram of the internal resistance variation curves under different discharge rates provided in Embodiment 3 of this disclosure;

[0024] Figure 7 This is a schematic diagram of the structure of a detection device for the sodium deposition threshold of sodium-ion battery negative electrode material provided according to an embodiment of this disclosure. Detailed Implementation

[0025] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this disclosure.

[0026] The following explains some of the terms used in the embodiments of this disclosure.

[0027] Sodium deposition phenomenon: During charging, if the sodium storage potential of the negative electrode material is very close to the sodium deposition potential, then when the battery voltage is only slightly higher than 0V, the negative electrode material may begin to deposit metallic sodium instead of storing sodium ions. This deposition process is called sodium deposition.

[0028] SOC (State of Charge): A parameter used to describe the current remaining charge of a battery, usually expressed as a percentage, ranging from 0% (fully discharged) to 100% (fully charged).

[0029] With the rapid increase in energy demand and the rise of environmentalism, traditional fossil fuels can no longer meet the current energy demand structure. Improving energy utilization efficiency and developing large-scale electrochemical energy storage devices is an inevitable trend in future energy development. Sodium-ion batteries have broad application prospects due to their superior cost-effectiveness, safety, and low-temperature performance compared to lithium-ion batteries. However, because the sodium storage potential and sodium deposition potential of sodium-ion batteries are very close (0V), sodium deposition easily occurs in the negative electrode material during charging, affecting battery cycle life and safety.

[0030] Traditional methods for detecting sodium deposition in sodium-ion batteries mainly involve disassembling the battery to observe the sodium deposition situation. This method is cumbersome, and due to the reactive nature of sodium, it is difficult to accurately determine the sodium deposition threshold of the negative electrode material.

[0031] To address the shortcomings of traditional methods, several new detection technologies have been proposed. However, existing methods for detecting sodium deposition in sodium-ion batteries still have certain limitations.

[0032] One method is to observe sodium deposition using a three-electrode system. While the location of sodium deposition can be determined relatively intuitively using a three-electrode system, sodium, due to its reactive chemical properties and soft texture, makes three-electrode assembly either impossible or overly complicated.

[0033] Another method is to determine the sodium deposition potential and degree of sodium deposition in a sodium-ion battery by conducting charge-discharge tests. This method mainly tests the entire sodium-ion battery, but the overall test cannot distinguish the specific reactions of each part inside the battery, especially it cannot accurately measure the sodium deposition behavior of the negative electrode material alone. Therefore, it is also difficult to accurately determine the sodium deposition threshold of the negative electrode material itself.

[0034] Based on this, in a first aspect, Embodiment 1 of this disclosure provides a method for detecting the sodium deposition threshold of a sodium-ion battery anode material, referring to... Figure 1 As shown, Figure 1 This is a flowchart provided in Example 1 of the method for detecting the sodium deposition threshold of sodium-ion battery anode materials according to this disclosure.

[0035] like Figure 1 As shown, the method for detecting the sodium deposition threshold of the sodium-ion battery anode material may include steps S101 to S105:

[0036] Step S101: Assemble the negative electrode material to be tested into a half-cell system.

[0037] In some embodiments, the half-cell system can be a button cell system, and the negative electrode material is assembled into a half-cell system in the form of a negative electrode sheet. The half-cell system can be assembled according to the following components: negative electrode shell, sodium sheet, separator, negative electrode sheet, gasket, spring sheet, and positive electrode shell.

[0038] Taking a coin cell as an example, the fabrication of a coin cell includes the following components: counter electrode / reference electrode (pure sodium sheet, 14 mm in diameter), negative electrode sheet, separator (e.g., glass fiber separator GF-D), electrolyte (e.g., ester electrolyte, 1 M NaPF6 in a mixed solvent with a volume ratio of DMC:EC:EMC = 1:1:1), and casing assembly (coin cell type 2032, made of 316 stainless steel).

[0039] The negative electrode sheet is composed of the following: the negative electrode current collector is aluminum foil with a thickness ranging from 4 micrometers to 12 micrometers. The negative electrode active material can be one or more of the negative electrode materials prepared above, biomass hard carbon, resin-based hard carbon, fossil fuel-based hard carbon materials, etc.; the negative electrode conductive agent can be selected from one or more of conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene, or carbon nanotubes; the negative electrode binder can be selected from one or more of carboxymethyl cellulose, styrene-butadiene latex, polypropylene, polyethylene, polyvinylidene fluoride, chlorofluoroethylene-hexafluoropropylene, polytetrafluoroethylene, or polyhexafluoropropylene.

[0040] The diaphragm is selected as follows: a composite diaphragm based on polypropylene (PP) / polyethylene (PE) / polypropylene (PP) with ceramic / alumina or other materials coated on both sides.

[0041] The electrolyte is composed of sodium salt, electrolyte solvent and additives to form an electrolyte system suitable for sodium-ion battery operation.

[0042] For example, commercially available biomass hard carbon materials can be used for research. A slurry is prepared in water according to the main material: SP: carboxymethyl cellulose (CMC): styrene-butadiene latex (SBR) = 94.7:1.4:1.2:2.7 mass ratio. This slurry is then manually coated onto a 13μm thick aluminum foil using a doctor blade to a thickness of 100μm. After baking at 90°C for 30 min, the electrode sheet is rolled to approximately 70μm using a roller press, then punched into 12mm small discs and baked in a 110°C vacuum oven for 12 h. A coin cell is assembled in the following order: negative electrode shell, sodium sheet, separator, electrode sheet, gasket, spring sheet, and positive electrode shell. The electrolyte (1M NaPF6 in DMC:EC:EMC = 1:1:1 Vol%) is injected in 8 drops, and the cell is sealed under a pressure of 700KG. This yields half-cell system A.

[0043] It should be noted that, since the half-cell system involves only the reaction of one electrode, researchers can focus on studying the electrochemical behavior of a specific anode material without being disturbed by the reactions of other electrodes in the full cell. Therefore, this disclosure assembles anode materials into a half-cell system, which allows for the precise determination of the sodium deposition threshold of the anode material.

[0044] Step S102: Discharge the half-cell system multiple times using a constant current.

[0045] The discharge process of the half-cell system is the process by which the half-cell system stores sodium.

[0046] In some embodiments, prior to multiple discharges of the half-cell system using a constant current, the process may further include: forming the half-cell system using a formation current, wherein the formation current is 0.01C to 0.1C. It is understood that C is a unit representing a charge / discharge rate, where 1C means completing a full charge or discharge of the battery within one hour. For example, if a battery has a rated capacity of 100mAh, then a 1C current is 100mA.

[0047] It should be noted that formation refers to the initial charging process performed on a new lithium-ion or sodium-ion battery during its manufacturing process. This process uses a relatively small current to charge and discharge the battery, aiming to form a stable solid electrolyte interphase (SEI) film. The SEI film protects the negative electrode of the battery, preventing further decomposition of the electrolyte and improving the battery's cycle stability and safety.

[0048] For sodium-ion batteries, due to the chemical reactivity of sodium, the formation of a stable SEI film is crucial for battery performance. Using a formation current of 0.01C to 0.1C helps to form a uniform and stable SEI film on the negative electrode surface, thereby protecting the battery during subsequent charge and discharge processes, reducing irreversible capacity loss, and improving battery cycle life and safety.

[0049] Following the formation process, a capacity grading step is typically performed. Capacity grading involves conducting a series of charge-discharge cycles on the battery after formation, measuring various battery parameters, and classifying and grouping the batteries based on these parameters. Through capacity grading, battery cells with consistent performance can be selected, providing a foundation for balanced management and performance optimization of the battery pack.

[0050] For example, half-cell system A is pre-formed at a current density of 0.1 mA / cm² (approximately 0.05 C), with a charge / discharge window of 0-2 V. This pre-formation and capacity testing is performed to avoid solvent side reactions.

[0051] Step S103: Obtain the voltage change of the half-cell system after each discharge.

[0052] For example, half-cell system A is discharged with a constant current, and the voltage change of half-cell system A is recorded after each discharge.

[0053] Step S104: Based on the voltage change of the half-cell system after each discharge, determine the internal resistance change curve of the half-cell system throughout the entire discharge process.

[0054] In some embodiments, such as Figure 3 As shown, step S104 may include steps S301 to S302.

[0055] Step S301: Based on the voltage change of the half-cell system after each discharge, determine the internal resistance value of the half-cell system after each discharge.

[0056] Step S302: Based on the internal resistance value of the half-cell system after each discharge, determine the internal resistance value change curve of the half-cell system throughout the entire discharge process.

[0057] Since the current is constant, the change in the internal resistance of the half-cell system can be calculated based on the voltage change of the half-cell system after each discharge, thus obtaining the curve of the internal resistance change of the half-cell system throughout the entire discharge process.

[0058] Step S105: Based on the internal resistance change curve, determine the sodium deposition threshold of the negative electrode material in the half-cell system.

[0059] It should be noted that due to sodium deposition, a parallel circuit is formed between the sodium-deposited layer and the negative electrode, altering the trend of system resistance. During sodium storage, if sodium deposition occurs, the sodium-deposited layer on the electrode surface will form a parallel circuit with the negative electrode, causing a decrease in system resistance. Therefore, the sodium deposition threshold of the negative electrode material in the half-cell system can be determined based on the internal resistance change curve.

[0060] The sodium deposition threshold detection method for sodium-ion battery anode materials provided in this disclosure determines whether sodium deposition has occurred and establishes the sodium deposition threshold of the anode material by monitoring the change in system resistance during half-cell testing. Compared to existing sodium deposition detection methods for sodium-ion batteries, this method is characterized by its intuitiveness and non-destructive nature, while also providing a more accurate definition of the sodium deposition threshold for the anode material, thus providing information on the usable capacity of the corresponding anode material under specific usage conditions in subsequent production.

[0061] In the first aspect, based on Embodiment 1, Embodiment 2 of this disclosure provides a method for detecting the sodium deposition threshold of a sodium-ion battery anode material, referring to... Figure 2 As shown, Figure 2 This is a flowchart provided in Example 2 of the method for detecting the sodium deposition threshold of sodium-ion battery anode materials according to this disclosure.

[0062] In one feasible implementation, obtaining the voltage change of the half-cell system after each discharge may include steps S201 to S202.

[0063] Step S201: When the amount of electricity released by the half-cell system during each discharge process reaches a preset first electricity threshold, the discharge process is interrupted and the half-cell system is kept in a static state for a preset first duration.

[0064] The preset first power threshold can be 1% SOC, 1.5% SOC, 2% SOC, 5% SOC, etc., depending on the precision required for the study. For example, the preset first power threshold can be 1% SOC, meaning that each discharge discharge is at 1% SOC, and after each 1% SOC discharge, the voltage is held for a preset first duration. The purpose of this holding period is to obtain a stable voltage value.

[0065] Step S202: Within the first time period, obtain the voltage change of the half-cell system after each discharge.

[0066] This disclosure primarily studies the behavior of a half-cell system during sodium storage. Obtaining the voltage change of the half-cell system after each discharge allows for precise measurement of the voltage response after reaching a specific charge threshold.

[0067] In some embodiments, the constant current can be from 0.1C to 5C, the first charge threshold can be from 0.1% SOC to 5% SOC, and the first duration can be from 1s to 5s.

[0068] Preferably, the constant current is 0.5C, the first charge threshold is 1% SOC, and the first duration is 3s.

[0069] For example, half-cell system A is discharged with a constant current of 0.1C0 (C0 is the actual capacity of the battery after formation). Every 6 minutes of discharge (1% SOC) is followed by a 3-second rest period. This cycle is repeated 100 times. The voltage change before and after the rest period is recorded. The internal resistance of half-cell system A is calculated based on this.

[0070] The method for detecting the sodium deposition threshold of sodium-ion battery anode materials provided in this disclosure can more accurately determine the sodium deposition threshold of sodium-ion battery anode materials by controlling the discharge capacity and measuring voltage changes.

[0071] In the first aspect, based on Embodiment 1, Embodiment 3 of this disclosure provides a method for detecting the sodium deposition threshold of a sodium-ion battery anode material, referring to... Figure 4 As shown, Figure 4 This is a flowchart provided in Example 3 of the method for detecting the sodium deposition threshold of sodium-ion battery anode materials according to this disclosure.

[0072] In one feasible implementation, such as Figure 4 As shown, determining the sodium deposition threshold of the negative electrode material in the half-cell system based on the internal resistance change curve may include steps S401 to S402.

[0073] Step S401: Based on the internal resistance change curve, determine the decay inflection point of the internal resistance change curve.

[0074] In some embodiments, such as Figure 5 As shown, step S401 may include steps S501 to S502.

[0075] Step S501: If the trend of the internal resistance change curve is first decreasing, then leveling off, and then decreasing again, then the point of the second decrease is taken as the decay inflection point of the internal resistance change curve.

[0076] Step S502: If the trend of the internal resistance value change curve is first decreasing and then continuously decreasing, then the point of continuous decrease is taken as the decay inflection point of the internal resistance value change curve.

[0077] Step S402: Based on the decay inflection point, determine the sodium deposition threshold of the negative electrode material in the half-cell system.

[0078] The sodium precipitation threshold is the amount of electricity cumulatively released by the half-cell system corresponding to the decay inflection point.

[0079] For example, half-cell system B and half-cell system D were prepared using the method of Example 1. Half-cell system B was discharged with a constant current of 0.1C0 (C0 is the actual capacity of the battery after formation), and then rested for 3 seconds every 6 minutes (1% SOC), and this cycle was repeated 100 times. The voltage changes before and after the resting period were recorded, and the DC internal resistance value was calculated. Half-cell system D was discharged with a constant current of 0.5C0 (C0 is the actual capacity of the battery after formation), and then rested for 3 seconds every 6 minutes (1% SOC), and this cycle was repeated 100 times. The voltage changes before and after the resting period were recorded, and the DC internal resistance value was calculated. The internal resistance value change curves at 0.1C0 and 0.5C0 are shown below. Figure 6 As shown. Reference Figure 6 The internal resistance of half-cell system B did not show a rapid decay inflection point, indicating that sodium deposition did not occur at this point. The internal resistance of half-cell system D began to show a rapid decay inflection point at 91% SOC, indicating that sodium deposition occurred at this point. The sodium deposition threshold corresponds to 91% SOC.

[0080] Because the accuracy of the sodium precipitation threshold varies with different magnifications, a more accurate sodium precipitation threshold can be obtained by changing the magnification.

[0081] The method for detecting the sodium deposition threshold of sodium-ion battery anode materials provided in this disclosure determines the decay inflection point by accurately analyzing the internal resistance change curve, thereby accurately evaluating the sodium deposition threshold of the anode material.

[0082] Based on this, in a second aspect, embodiments of this disclosure provide a detection device for the sodium deposition threshold of a sodium-ion battery negative electrode material, referring to... Figure 7 As shown, Figure 7This is a schematic diagram of the structure of a detection device for the sodium deposition threshold of sodium-ion battery negative electrode material provided according to an embodiment of this disclosure.

[0083] like Figure 7 As shown, the sodium deposition threshold detection device 100 for the sodium-ion battery negative electrode material includes an assembly unit 110, a discharge test unit 120, a voltage acquisition unit 130, and a determination unit 140.

[0084] Assembly unit 110 is used to assemble the negative electrode material to be tested into a half-cell system.

[0085] The discharge test unit 120 is used to discharge the half-cell system multiple times using a constant current.

[0086] The voltage acquisition unit 130 is used to acquire the voltage change of the half-cell system after each discharge.

[0087] The determination unit 140 determines the internal resistance change curve of the half-cell system throughout the entire discharge process based on the voltage change of the half-cell system after each discharge; and determines the sodium deposition threshold of the negative electrode material of the half-cell system based on the internal resistance change curve.

[0088] The sodium deposition threshold detection device for sodium-ion battery anode materials provided in this disclosure adopts the sodium deposition threshold detection method for sodium-ion battery anode materials in the above embodiments, and can solve the technical problems mentioned in the background art.

[0089] The beneficial effects of the sodium deposition threshold detection device for sodium-ion battery anode materials provided in this disclosure are the same as those of the sodium deposition threshold detection method for sodium-ion battery anode materials provided in the above embodiments. Furthermore, the other technical features of the sodium deposition threshold detection device for sodium-ion battery anode materials are the same as those disclosed in the sodium deposition threshold detection method for sodium-ion battery anode materials, and will not be repeated here.

[0090] It should be noted that although the terms "first," "second," etc., are used herein to describe different modules, steps, and data in the embodiments of this disclosure, these terms are only for distinguishing between different modules, steps, and data, and do not indicate a specific order or degree of importance. In fact, the terms "first," "second," etc., can be used interchangeably.

[0091] Although the operations are described in a specific order in the accompanying drawings, this should not be construed as requiring these operations to be performed in the specific order or serial order shown, or requiring all of the operations shown to obtain the desired result. In certain environments, multitasking and parallel processing may be advantageous.

[0092] The acquisition, transmission, storage, use, and processing of data in this embodiment comply with the relevant provisions of national laws and regulations.

[0093] It should be noted that in the embodiments disclosed herein, certain software, components, models, and other existing solutions in the industry may be mentioned. These should be considered as exemplary and are intended only to illustrate the feasibility of implementing the technical solutions disclosed herein. However, they do not mean that the applicant has used or necessarily used such solutions.

[0094] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0095] The above are merely embodiments of this disclosure and are not intended to limit the scope of this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of the claims of this disclosure.

Claims

1. A method for detecting the sodium deposition threshold of a sodium-ion battery negative electrode material, characterized in that, include: The negative electrode material to be tested is assembled into a half-cell system; The half-cell system was discharged multiple times using a constant current. Obtain the voltage change of the half-cell system after each discharge; Based on the voltage change of the half-cell system after each discharge, the internal resistance change curve of the half-cell system during the entire discharge process is determined. Based on the internal resistance change curve, the sodium deposition threshold of the negative electrode material of the half-cell system is determined.

2. The method for detecting the sodium deposition threshold of sodium-ion battery negative electrode material according to claim 1, characterized in that, The step of obtaining the voltage change of the half-cell system after each discharge includes: When the amount of electricity released by the half-cell system during each discharge process reaches a preset first electricity threshold, the discharge process is interrupted and the half-cell system is kept in a static state for a preset first duration. Within the first time period, the voltage change of the half-cell system after each discharge is acquired.

3. The method for detecting the sodium deposition threshold of sodium-ion battery negative electrode material according to claim 2, characterized in that, The constant current is 0.1C to 5C, the first charge threshold is 0.1%SOC to 5%SOC, and the first duration is 1s to 5s.

4. The method for detecting the sodium deposition threshold of sodium-ion battery negative electrode material according to claim 3, characterized in that, The constant current is 0.5C, the first charge threshold is 1% SOC, and the first duration is 3s.

5. The method for detecting the sodium deposition threshold of sodium-ion battery negative electrode material according to claim 1, characterized in that, The determination of the internal resistance change curve of the half-cell system throughout the entire discharge process based on the voltage change of the half-cell system after each discharge includes: Based on the voltage change of the half-cell system after each discharge, the internal resistance value of the half-cell system after each discharge is determined. Based on the internal resistance value of the half-cell system after each discharge, the curve of the internal resistance value change of the half-cell system throughout the entire discharge process is determined.

6. The method for detecting the sodium deposition threshold of sodium-ion battery negative electrode material according to claim 1, characterized in that, Determining the sodium deposition threshold of the negative electrode material in the half-cell system based on the internal resistance change curve includes: Based on the internal resistance change curve, determine the decay inflection point of the internal resistance change curve; Based on the decay inflection point, the sodium deposition threshold of the negative electrode material of the half-cell system is determined, wherein the sodium deposition threshold is the amount of electricity cumulatively released by the half-cell system corresponding to the decay inflection point.

7. The method for detecting the sodium deposition threshold of sodium-ion battery negative electrode material according to claim 6, characterized in that, Determining the attenuation inflection point of the internal resistance change curve based on the internal resistance change curve includes: If the trend of the internal resistance value change curve is first decreasing, then leveling off, and then decreasing again, then the point of the second decrease is taken as the decay inflection point of the internal resistance value change curve. If the trend of the internal resistance change curve is first decreasing and then continuously decreasing, then the point of continuous decrease is taken as the decay inflection point of the internal resistance change curve.

8. The method for detecting the sodium deposition threshold of sodium-ion battery negative electrode material according to claim 1, characterized in that, Before repeatedly discharging the half-cell system using a constant current, the method further includes: The half-cell system is formed using a formation current, wherein the formation current is 0.01C to 0.1C.

9. The method for detecting the sodium deposition threshold of sodium-ion battery negative electrode material according to any one of claims 1 to 8, characterized in that, The half-cell system is a button cell half-cell system. The negative electrode material is assembled into a half-cell system in the form of a negative electrode sheet. The half-cell system is assembled according to the following components: negative electrode shell, sodium sheet, separator, negative electrode sheet, gasket, spring sheet, and positive electrode shell.

10. A device for detecting the sodium deposition threshold of a sodium-ion battery negative electrode material, characterized in that, include: The assembly unit is used to assemble the negative electrode material to be tested into a half-cell system. A discharge test unit is used to discharge the half-cell system multiple times using a constant current. A voltage acquisition unit is used to acquire the voltage change of the half-cell system after each discharge. The unit determines the internal resistance change curve of the half-cell system throughout the entire discharge process based on the voltage change of the half-cell system after each discharge. And for determining the sodium deposition threshold of the negative electrode material of the half-cell system based on the internal resistance change curve.

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