Carrier stage electrode, potential detection system and method

Abstract

The embodiment of the invention discloses a carrier electrode, a potential detection system and a potential detection method, which are used for detecting the potential of target powder. The carrying platform electrode comprises an extension part and a bearing part; the extension part comprises a conductive part and an isolation part wrapping the conductive part; the isolation part is connected with the bearing component; a containing cavity is formed in the bearing component and used for containing target powder, and the conductive part extends into the containing cavity; the bearing part is provided with a diffusion hole which is communicated with the containing cavity. According to the embodiment of the invention, under the condition that the powder is not compressed into a button battery, the potential of the powder coated on the surface of the battery electrode can be measured, so that the powder does not need to be damaged; and the required powder amount is smaller, that is, the potential of the trace powder can be measured, so that the amount of the powder used for measuring the potential can be reduced, and the powder potential measurement cost is saved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of potential measurement, and in particular to a carrier electrode, a potential detection system and a method. BACKGROUND

[0002] A power battery is an energy source of a new energy vehicle. Uniformity of a material coated on a surface of a positive or negative electrode tab of the power battery is an important factor affecting working performance of the power battery. If the material coated on the surface of the battery electrode tab is not uniform enough, problems such as obvious local temperature rise of each cell in the power battery during charging and discharging may be caused, and abnormal phenomena such as local purple stains or lithium precipitation on the surface of the battery electrode tab are easily caused.

[0003] The material coated on the surface of the battery electrode tab constitutes a conductive whole with each other, and it is impossible to directly determine whether the material coated on the surface of the battery electrode tab is uniform on the electrode, so the powder is usually assembled into a form of a button cell for potential measurement of the powder. However, assembling into the button cell may cause certain destructive damage to the powder. Therefore, how to measure the potential of the powder without causing damage to the powder is a problem to be solved at present. SUMMARY

[0004] The carrier electrode, the potential detection system and the method provided by the embodiments of the present application solve the technical problem that assembling into a button cell for potential measurement of powder causes certain destructive damage to the powder in the prior art, and achieve the technical effect of measuring the voltage of the powder without causing damage to the powder.

[0005] In a first aspect, the present application provides a carrier electrode applied to a potential detection system including an electrolyte, the potential detection system being used for detecting a potential of a target powder. The carrier electrode includes an extension component and a bearing component; the extension component includes a conductive part and an isolation part wrapped outside the conductive part; the isolation part is connected with the bearing component; the materials of the isolation part and the bearing component are insulating materials; the isolation part is used for isolating the conductive part and the electrolyte when the potential detection system detects the potential of the target powder; The bearing component is internally arranged with a containing cavity, the containing cavity being used for containing the target powder, and the conductive part extends to the containing cavity to contact the target powder when the potential detection system detects the potential of the target powder; The bearing component is provided with a diffusion hole, the diffusion hole being in communication with the containing cavity to realize ion diffusion between the target powder and the electrolyte when the potential detection system detects the potential of the target powder.

[0006] In some embodiments of the present application, based on the foregoing scheme, the bearing component comprises a bearing body, a cover plate and a fastener, the bearing body is provided with a groove for filling the target powder from the opening inwardly; the cover plate covers the opening of the groove by the fastener, so that the groove forms the containing cavity; the diffusion hole is arranged on the cover plate.

[0007] In some embodiments of the present application, based on the foregoing scheme, the material of the isolation part and the bearing component is an organic material or a ceramic material.

[0008] In some embodiments of the present application, based on the foregoing scheme, the isolation part and the bearing component are integrally formed.

[0009] In some embodiments of the present application, based on the foregoing scheme, the inner diameter of the containing cavity ranges from 1mm to 20mm.

[0010] In some embodiments of the present application, based on the foregoing scheme, the inner diameter of the containing cavity ranges from 1mm to 5mm.

[0011] In the second aspect, the present application provides a potential detection system for detecting the potential of the target powder, which comprises a reference electrode, an electrolyte, a voltage measurer, a container and a carrier electrode provided in the first aspect; One end of the reference electrode is placed in the electrolyte contained in the container, and the containing cavity of the carrier electrode for containing the target powder is placed in the electrolyte; One measurement end of the voltage measurer is connected with the other end of the reference electrode, and the other measurement end of the voltage measurer is connected with the conductive part of the carrier electrode, so as to determine the potential of the target powder based on the Kirchhoff's law and the voltage measurement value of the voltage measurer.

[0012] In some embodiments of the present application, based on the foregoing scheme, the reference electrode is a lithium metal sheet, a copper-lithium composite foil or a lithium iron phosphate positive electrode sheet with a preset lithium ion deintercalation ratio.

[0013] In some embodiments of the present application, based on the foregoing scheme, the electrolyte is the electrolyte of a lithium battery.

[0014] In some embodiments of the present application, based on the foregoing scheme, the measurement resolution of the voltage measurer is 0.00001V.

[0015] In some embodiments of the present application, based on the foregoing scheme, the container is made of one of quartz glass, polytetrafluoroethylene and expanded glass.

[0016] In some embodiments of the present application, based on the foregoing scheme, the equivalent resistance between the reference electrode and the carrier electrode is a first resistance, and the equivalent resistance between the reference electrode and the target powder is a second resistance, and the first resistance has a greater resistance value than the second resistance.

[0017] In a third aspect, the present application provides a potential measurement method, which is applicable to the potential detection system provided in the first aspect, and the potential measurement method comprises: adding the target powder to be measured into the accommodating cavity of the carrier electrode; immersing the accommodating cavity into the electrolyte in the container completely; and immersing one end of the reference electrode into the electrolyte; connecting one measurement end of the voltage measurer to the conductive part, and connecting the other measurement end of the voltage measurer to the other end of the reference electrode; collecting a first voltage value displayed by the voltage measurer; determining the actual potential of the target powder based on the first voltage value and Kirchhoff's law.

[0018] In some embodiments of the present application, based on the foregoing scheme, before the target powder to be measured is added into the accommodating cavity of the carrier electrode, the potential measurement method further comprises: calibrating the potential of the reference electrode.

[0019] In some embodiments of the present application, based on the foregoing scheme, before the target powder to be measured is added into the accommodating cavity of the carrier electrode, after the potential of the reference electrode is calibrated, the potential measurement method further comprises: adding a reference powder having a reference potential into the accommodating cavity; immersing the accommodating cavity into the electrolyte completely; and immersing one end of the reference electrode into the electrolyte; connecting one measurement end of the voltage measurer to the conductive part, and connecting the other measurement end of the voltage measurer to the other end of the reference electrode; collecting a second voltage value displayed by the voltage measurer; determining a measured potential of the reference powder based on the second voltage value and Kirchhoff's law; determining an accuracy threshold value for characterizing the accuracy of the potential measurement of the potential detection system according to the measured potential and the reference potential; measuring the potential of the target powder to be measured again in the case that the accuracy threshold value meets a preset accuracy requirement.

[0020] In some embodiments of the present application, based on the foregoing scheme, after the accommodation cavity is completely immersed in the electrolyte contained in the container, before collecting the first voltage value displayed by the voltage measurer, the method further comprises: The duration of the complete immersion of the accommodation cavity in the electrolyte reaches a preset duration, and the preset duration is a duration greater than or equal to 30 seconds.

[0021] In a fourth aspect, the present application provides a battery pole piece surface uniformity detection method, the detection method comprising: Scraping off the powder coated on at least two different regions of the target battery pole piece surface, and respectively adopting the potential measurement method provided in the third aspect to obtain the actual potential of the powder in each region; According to the actual potential of each region, determining a determination result characterizing the uniformity of the material coated on the target battery pole piece surface.

[0022] In some embodiments of the present application, based on the foregoing scheme, the detection method further comprises: In the case where the determination result characterizes that the material coated on the target battery pole piece surface is not uniform, adjusting the content of the powder in each region according to the difference between the actual potentials of each region, and re-producing a battery pole piece of the same type as the target battery pole piece, so that the material coated on the re-produced battery pole piece surface meets the uniformity requirement.

[0023] In a fifth aspect, the present application provides a battery pole piece quality inspection method, the inspection method comprising: Selecting at least two battery pole pieces from the same batch of battery pole pieces produced using the same production parameters as target battery pole pieces, and adopting the battery pole piece surface uniformity detection method provided in the fourth aspect to determine a determination result characterizing the uniformity of the material coated on the surface of each target battery pole piece; According to the determination result of each target battery pole piece, determining whether the quality of the batch of battery pole pieces is qualified.

[0024] In some embodiments of the present application, based on the foregoing scheme, the method further comprises: In the case where it is determined that the quality of the batch of battery pole pieces is unqualified, optimizing and adjusting the production parameters of the batch of battery pole pieces, and re-producing battery pole pieces using the optimized and adjusted production parameters, so that the quality of the re-produced battery pole pieces is qualified.

[0025] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages: The embodiment of the present application provides a carrier electrode, which comprises an extension component and a bearing component; the extension component comprises a conductive part and an isolation part wrapped outside the conductive part; the isolation part is connected with the bearing component; the isolation part and the bearing component are made of insulating materials; the isolation part is used for isolating the conductive part and the electrolyte when the potential detection system detects the potential of the target powder; the bearing component is internally arranged with a containing cavity used for containing the target powder, and the conductive part extends to the containing cavity to be in contact with the target powder when the potential detection system detects the potential of the target powder; the bearing component is provided with diffusion holes in communication with the containing cavity to realize ion diffusion between the target powder and the electrolyte when the potential detection system detects the potential of the target powder. In the embodiment of the present application, the potential of the powder coated on the surface of the battery electrode can be measured without compressing the powder into a button cell, and then the powder can not be damaged, so that the reusability of the powder can be improved. Further, since the embodiment of the present application does not need to compress the powder into a button cell, the amount of powder required is smaller, that is, the potential of the micro powder can be measured, so that the amount of powder used for measuring the potential can be reduced, and the measurement cost of the powder potential can be saved.

[0026] The embodiment of the present application does not need to use pulse signals such as electric signals and laser signals to measure the potential of the powder, so that the state of the powder material can be avoided to be changed by the two kinds of signals, the introduction of error terms is reduced, and the measurement result is more accurate. In addition, the embodiment of the present application measures the potential of the powder in the state that the powder and the battery are independent of each other, so that the battery does not need to be charged to different states to disassemble and test the local voltage, so that the iron lithium, ternary or graphite is in the same lithium intercalation state and belongs to the equilibrium state, and the measurement accuracy of the potential of the powder is ensured.

[0027] The application embodiment scrapes off the powder coated on at least two different regions of the target battery pole piece surface, respectively uses the aforementioned potential measurement method to obtain the actual potential of the powder in each region, and determines the determination result representing the uniformity of the material coated on the target battery pole piece surface according to the actual potential of each region. It can be seen that the application embodiment can determine whether the powder material coated on the battery pole piece surface is uniform by measuring the potential of the powder coated on each region of the battery pole piece surface, so as to check whether the produced battery pole piece is qualified, thereby improving the production quality and consistency of the battery pole piece. In this way, various non-uniformities of the positive and negative pole pieces can be reduced as much as possible, such as non-uniformity of the particle size distribution of the raw material, non-uniformity of the particle distribution and stress state in the slurry mixing, coating and rolling process, and non-uniformity of the local temperature rise of the structure of the battery cell in the charging and discharging process, thereby reducing the occurrence probability of local purple spots or lithium precipitation and improving the use safety and service life of the battery. The application embodiment can be applied in the research and development process of new battery pole pieces, such as crimped pole pieces, by measuring the potential of the powder coated on each region of the battery pole piece surface to determine whether the powder material coated on the battery pole piece surface is uniform, so as to adjust the content of the powder material in each different crimped region of the battery pole piece, thereby improving the charging and discharging performance of the battery pole piece and shortening the development cycle of the new battery pole piece.

[0028] The application embodiment selects at least two battery pole pieces as target battery pole pieces from the same batch of battery pole pieces produced by using the same production parameters, determines the determination result representing the uniformity of the material coated on the surface of each target battery pole piece by using the aforementioned battery pole piece surface uniformity detection method, and determines whether the quality of the battery pole pieces of the batch is qualified according to the determination result of each target battery pole piece. It can be seen that the application embodiment can detect the samples from the battery pole pieces of the same batch to measure whether the powder coated on each region of the surface of the battery pole pieces produced in the current batch is uniform, so as to check whether the battery pole pieces produced in the current batch are qualified. If the battery pole pieces of the current batch are generally unqualified, it means that the production parameters are abnormal, and the production parameters need to be adjusted, thereby improving the production quality and consistency of the battery pole piece. In this way, various non-uniformities of the produced positive and negative pole pieces can be reduced as much as possible, such as non-uniformity of the particle size distribution of the raw material, non-uniformity of the particle distribution and stress state in the slurry mixing, coating and rolling process, and non-uniformity of the local temperature rise of the structure of the battery cell in the charging and discharging process, thereby reducing the occurrence probability of local purple spots or lithium precipitation and improving the use safety and service life of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained based on these drawings without creative labor.

[0030] Figure 1 A structural schematic diagram of a potential detection system provided by an embodiment of the present application; Figure 2 A structural schematic diagram of a carrier electrode provided by an embodiment of the present application; Figure 3 A structural schematic diagram of another carrier electrode provided by an embodiment of the present application; Figure 4 A structural schematic diagram of a potential detection system provided by an embodiment of the present application; Figure 1 An equivalent circuit structural schematic diagram of the system shown in the figure; Figure 5 A flow schematic diagram of a potential measurement method provided by an embodiment of the present application; Figure 6 A flow schematic diagram of a battery electrode sheet surface uniformity detection method provided by an embodiment of the present application; Figure 7 A flow schematic diagram of a battery electrode sheet quality inspection method provided by an embodiment of the present application.

[0031] Reference signs: 1-reference electrode, 2-carrier electrode, 3-container, 4-electrolyte, 5-voltage measurer, 6-target powder; 21-extension component, 211-conductive part, 212-isolation part, 22-bearing component, 221-receiving cavity, 222-bearing body, 223-cover plate, 224-fastener. DETAILED DESCRIPTION

[0032] The embodiments of the present application provide a carrier electrode, a potential detection system and a method, and solve the technical problem that the assembly of a button cell for measuring the potential of powder causes certain destructive damage to the powder in the prior art.

[0033] The technical solutions of the embodiments of the present application are as follows to solve the above technical problems: The embodiment of the present application provides a carrier electrode, the carrier electrode 2 comprises an extension component 21 and a bearing component 22; the extension component 21 comprises a conductive part 211 and an isolation part 212 wrapped outside the conductive part 211; the isolation part 212 is connected with the bearing component 22; the materials of the isolation part 212 and the bearing component 22 are insulating materials; the isolation part 212 is used for isolating the conductive part 211 and the electrolyte 4 when the potential detection system detects the potential of the target powder 6; the bearing component 22 is internally arranged with a containing cavity 221, the containing cavity 221 is used for containing the target powder 6, the conductive part 211 extends into the containing cavity 221, so as to contact the target powder 6 when the potential detection system detects the potential of the target powder 6; the bearing component 22 is provided with a diffusion hole, the diffusion hole is communicated with the containing cavity 221, so that ion diffusion between the target powder 6 and the electrolyte 4 is realized when the potential detection system detects the potential of the target powder 6. In the embodiment of the present application, the potential of the powder coated on the surface of the battery electrode can be measured without compressing the powder into a button cell, and then the powder can not be damaged, so that the reuse rate of the powder can be improved. Further, since the powder does not need to be compressed into a button cell in the embodiment of the present application, the amount of powder required is smaller, that is, the potential of the trace powder can be measured, so that the amount of powder used for measuring the potential can be reduced, and the cost of powder potential measurement can be saved.

[0034] The embodiment of the present application does not need to use pulse signals such as electric signals and laser signals to measure the potential of the powder, so that the state of the powder material can be avoided to be changed by the two kinds of signals, the introduction of error terms is reduced, and the measurement result is more accurate. In addition, the embodiment of the present application measures the potential of the powder in a state that the powder and the battery are independent of each other, so that the battery needs to be charged to different states to disassemble and test the local voltage, so that the iron lithium, ternary or graphite is in the same lithium intercalation state, belongs to the equilibrium state, and the measurement accuracy of the potential of the powder is ensured.

[0035] The application can determine whether the powder material coated on the surface of the battery pole piece is uniform by measuring the potential of the powder coated on each region of the surface of the battery pole piece, so as to check whether the produced battery pole piece is qualified, thereby improving the production quality and consistency of the battery pole piece. In this way, various non-uniformities of the positive and negative pole pieces can be reduced as much as possible, such as non-uniformity of the particle size distribution of the raw material, non-uniformity of the particle distribution and stress state in the slurry mixing, coating and rolling processes, and non-uniformity of the local temperature rise of the structure of the battery cell in the charging and discharging process, thereby reducing the probability of occurrence of local purple spots or lithium precipitation and improving the use safety and service life of the battery. The application can be applied in the research and development process of new battery pole pieces, such as crimped pole pieces, so as to adjust the content of the powder material in each different crimped region of the battery pole piece, thereby improving the charging and discharging performance of the battery pole piece and shortening the development cycle of the new battery pole piece.

[0036] The application can determine whether the powder material coated on the surface of the battery pole piece is uniform by measuring the potential of the powder coated on each region of the surface of the battery pole piece, so as to check whether the produced battery pole piece is qualified, thereby improving the production quality and consistency of the battery pole piece. In this way, various non-uniformities of the positive and negative pole pieces can be reduced as much as possible, such as non-uniformity of the particle size distribution of the raw material, non-uniformity of the particle distribution and stress state in the slurry mixing, coating and rolling processes, and non-uniformity of the local temperature rise of the structure of the battery cell in the charging and discharging process, thereby reducing the probability of occurrence of local purple spots or lithium precipitation and improving the use safety and service life of the battery. The application can be applied in the research and development process of new battery pole pieces, such as crimped pole pieces, so as to adjust the content of the powder material in each different crimped region of the battery pole piece, thereby improving the charging and discharging performance of the battery pole piece and shortening the development cycle of the new battery pole piece.

[0037] In order to better understand the above technical solutions, the above technical solutions will be described in detail in conjunction with the drawings and specific embodiments of the specification.

[0038] Firstly, the term "and / or" appearing in the present document only describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone. In addition, the character " / " generally represents that the front and rear associated objects have an "or" relationship.

[0039] The embodiments of the present application are used for measuring potential, which refers to the potential energy of unit electric charge in an electric field. Potential is related to electrochemical potential. Regarding electrochemical potential, it is an important physical quantity describing the energy state of charged particles (such as ions or electrons) in an electrochemical system. It combines chemical potential and electric potential energy (also known as electric potential), and reflects the free energy change of particles under the joint action of chemical and electric fields. If the chemical potential is zero (or uniform), the electrochemical potential is determined only by the potential.

[0040] The embodiments of the present application provide a potential detection system for detecting the potential of target powder 6. The target powder 6 can be a material used for coating the surface of the electrode sheet of a battery. In the electrode sheet of a battery, the coated powder is different according to the battery type (lithium ion, sodium ion, solid-state battery, etc.) and the electrode function (positive / negative). For example, for the positive electrode sheet, the positive electrode material of the lithium ion battery can be a layered oxide, a phosphate, and a spinel material, and the positive electrode material of the sodium ion battery can be a Prussian blue analog and a layered oxide, etc. For the negative electrode sheet, it can be a carbon-based material such as graphite, hard carbon, and graphene composite, etc., or an alloy / conversion material such as silicon-based material, tin-based alloy, and lithium titanate, etc.

[0041] The embodiments of the present application record the powder to be measured as target powder 6. The target powder 6 can be the powder scraped from a certain area of the surface of the electrode sheet of a battery, and the target powder 6 can also be the production raw material used for coating the surface of the electrode sheet of a battery before coating. Further, the certain area of the surface of the electrode sheet of a battery can refer to any local area of the surface of the electrode sheet of a battery, and the size of the local area can be selected according to actual needs. For example, for a sheet-shaped electrode sheet, the surface of the electrode sheet can be equally divided into 10 areas, and then the powder obtained from each area is determined as the target powder 6. For a coiled electrode sheet, the powder in the bending area can be determined as the target powder 6, or the powder in the non-bending area can be determined as the target powder 6.

[0042] The potential detection system provided by the embodiments of the present application is shown in Figure 1 The detection system includes a reference electrode 1, an electrolyte 4, a voltage measurer 5, a container 3, and a carrier electrode 2.

[0043] One end of the reference electrode 1 is placed in the electrolyte 4 in the container 3, and the containing cavity 221 in the carrier electrode 2 for containing the target powder 6 is placed in the electrolyte 4; One measurement end of the voltage measurer 5 is connected to the other end of the reference electrode 1, and the other measurement end of the voltage measurer 5 is connected to the conductive part 211 of the carrier electrode 2, and then the potential of the target powder 6 is determined based on the Kirchhoff's law and the voltage measurement value of the voltage measurer 5.

[0044] The reference electrode 1 can be in the shape of a cylinder, a cuboid, etc., and can be selected according to actual conditions.

[0045] Further, the properties of the reference electrode 1 meet the preset requirements of the electrode, which include at least one of the non-deterioration requirement, the potential stability requirement, the electrochemical stability requirement, the thermal stability requirement, and the reversibility stability requirement.

[0046] The non-deterioration requirement means that the reference electrode 1 is kept intact and has no corrosion pits or changes in composition on the surface, such as being stored in an inert gas atmosphere and having no corrosion on the surface. In addition, the non-deterioration requirement can also mean that the electrode material does not undergo chemical corrosion, dissolution or phase change when the reference electrode 1 works in the electrolyte 4 for a long time, and the surface morphology and chemical composition remain in the initial state. The quantitative index can be a corrosion rate <0.1 nm / h, and the surface has no corrosion pits or changes in composition. The higher the non-deterioration requirement of the reference electrode 1, the smaller the degree of pollution of the electrolyte 4 in the potential detection process, and the smaller the negative impact of random potential fluctuations on the potential detection process.

[0047] The potential stability requirement means that the electrode potential (electric potential) in the electrochemical system remains relatively constant under certain conditions, and is usually not significantly affected by small currents or external disturbances. When the electrode reaction (such as the oxidation-reduction reaction) reaches a dynamic equilibrium, the net current on the electrode surface is zero, and the potential is stable at this time. The stable potential is not sensitive to small external currents or changes in concentration, that is, the polarization resistance is high, and the potential is not easy to drift. The open-circuit potential of the reference electrode 1 changes with time at a rate lower than a threshold value under the conditions of constant temperature and constant electrolyte composition. Quantitative index: short-term stability: 24-hour potential drift <±0.1 mV. Long-term stability: 30-day drift <±1 mV.

[0048] Electrochemical stability requirement refers to the ability of a material or system to maintain its chemical composition, structure, and performance unchanged in a specific electrochemical environment (such as electrolyte, potential range, etc.). It reflects the resistance of the material to oxidation, reduction, corrosion, or decomposition, and is a key indicator for evaluating the reliability of electrode materials, electrolytes, batteries, or corrosion protection systems. Broadly speaking, electrochemical stability refers to the fact that the material does not undergo irreversible chemical changes (such as decomposition, dissolution, phase transition) when an electric potential or current is applied. Narrowly speaking, electrochemical stability refers to the fact that the electrode material remains structurally stable during charging and discharging cycles, or the electrolyte does not decompose within the operating voltage window. The reference electrode 1 does not undergo irreversible reactions (such as electrolysis, passivation film rupture) at the interface when an electric current or potential scan is applied. The test method can be linear sweep voltammetry, i.e., the current response is linear within a ±10 mV window (deviation < 5%). Alternatively, an AC impedance spectroscopy method can be used, i.e., the charge transfer resistance is greater than 10 6 Ω·cm².

[0049] Thermal stability requirement refers to the predictability and reversibility of the potential of the reference electrode 1 with respect to temperature changes, which is usually characterized by the temperature coefficient (a).

[0050] Reversibility stability requirement refers to the ability of the reference electrode 1 to recover to the initial potential after experiencing redox disturbances (hysteresis effect evaluation). For example, specific evaluation parameters include: applying a ±5 mV step voltage, and recovering to within ±0.2 mV of the initial value within 30 minutes after removal. The potential change is < 0.3 mV after 100 cycles of charging and discharging cycles.

[0051] In the embodiments of the present application, the reference electrode 1 can be a lithium metal sheet, a copper-lithium composite foil, or a lithium iron phosphate positive electrode sheet with a preset lithium ion extraction ratio (which can be represented by State of Charge, abbreviated as SOC, SOC also referred to as State of Charge). The preset lithium ion extraction ratio can be 50%. Among them, the lithium metal sheet and the 50% SOC lithium iron phosphate positive electrode sheet are preferred. SOC represents the extraction ratio of lithium ions in the electrode material, i.e., the percentage of the current capacity to the maximum available capacity. The formula can be:

[0052] For example, lithium iron phosphate (LiFePO4) is completely delithiated to FePO4, corresponding to an SOC of 0%. Lithium ions are completely inserted to restore to LiFePO4, corresponding to an SOC of 100%.

[0053] The electrolyte 4 is the electrolyte of the lithium battery. The electrolyte 4 needs to provide a lithium ion path for the detection system, and has electrochemical compatibility. Regarding the lithium ion path, the electrolyte 4 is the medium for the transmission of lithium ions (Li+) between the positive and negative electrodes of the battery, forming an ion conductive path. The lithium salt (such as LiPF6, lithium hexafluorophosphate) in the electrolyte 4 dissociates Li+, which moves directionally under an applied electric field or concentration gradient, completing the charge transfer. In experiments or tests (such as cyclic voltammetry, impedance testing), the electrolyte 4 needs to provide stable ion conduction to ensure that the data reflects the true performance of the electrode material, rather than being limited by the resistance or diffusion rate of the electrolyte 4. Regarding electrochemical compatibility, the electrolyte 4 must stably coexist with the reference electrode 1, the carrier electrode 2, the target powder 6, the container 3, etc. in terms of chemistry and electrochemistry, avoiding side reactions.

[0054] The measurement resolution of the voltage measurer 5 is 0.00001V. Since the embodiment of the present application measures the potential of the target powder 6, and the potential of the target powder 6 is small, the open-circuit voltage between the reference electrode 1 and the carrier electrode 2 and the target powder 6 is small, so a high-precision voltage measurer 5 is needed to measure the voltage difference. The measurement resolution is the measurement accuracy.

[0055] The container 3 needs to have chemical stability and can be made of one of quartz glass, polytetrafluoroethylene, and expanded glass. Among them, polytetrafluoroethylene is preferred.

[0056] The equivalent resistance between the reference electrode 1 and the carrier electrode 2 is a first resistance, the equivalent resistance between the reference electrode 1 and the target powder 6 is a second resistance, and the resistance value of the first resistance is greater than the resistance value of the second resistance. Moreover, the greater the difference between the first resistance and the second resistance, the more accurate the potential measured by the target powder, the reason for which will be explained later. It should be noted that the equivalent resistance between the reference electrode 1 and the carrier electrode 2 specifically refers to the equivalent resistance between the reference electrode 1 and the insulating part of the carrier electrode 2, and the insulating part refers to the isolation part 212 and the carrier part 22.

[0057] The embodiment of the present application also provides a carrier electrode applied to the potential detection system mentioned above. Figure 2As shown, the carrier electrode 2 comprises an extension part 21 and a carrier part 22; the extension part 21 comprises a conductive part 211 and an isolation part 212 wrapped outside the conductive part 211; the isolation part 212 is connected with the carrier part 22; the materials of the isolation part 212 and the carrier part 22 are insulating materials; the isolation part 212 is used to isolate the conductive part 211 and the electrolyte 4 when the potential detection system detects the potential of the target powder 6. The materials of the isolation part 212 and the carrier part 22 are insulating materials, which can minimize the interference and influence of the isolation part 212 and the carrier part 22 on the measurement of the potential of the target powder 6.

[0058] The carrier part 22 is internally arranged with a containing cavity 221 for containing the target powder 6, and the conductive part 211 extends into the containing cavity 221 to contact the target powder 6 when the potential detection system detects the potential of the target powder 6.

[0059] The carrier part 22 is provided with diffusion holes which are in communication with the containing cavity 221 to realize ion diffusion between the target powder 6 and the electrolyte 4 when the potential detection system detects the potential of the target powder 6. The pore size of the diffusion holes can be selected according to the diameter of the ions contained in the target powder 6. The pore size of the diffusion holes can be selected from the following ranges: for example, micropores less than 2 nm, such as MOFs and activated carbon; mesopores between 2 nm and 50 nm, such as alumina templates and mesoporous silica; macropores greater than 50 nm, such as porous ceramics and polymer filter membranes. In addition, the porosity of the diffusion holes is usually in the range of 30%-90%, such as the porosity of commercial lithium battery separators being 40%-60%. The porosity of high-performance ion exchange membranes is 60%-80%. The greater the porosity, the higher the ionic conductivity, but the lower the mechanical strength.

[0060] The extension part 21 comprises a conductive part 211 and an isolation part 212 wrapped outside the conductive part 211, and the conductive part 211 and the isolation part 212 can be a metal core of a conductive wire and an external insulating layer of the conductive wire, respectively. In addition, the isolation part 212 can be a columnar body with a through hole in the middle, and the conductive part 211 can be a conductive wire which penetrates into the through hole and contacts the space of the containing cavity 221. The columnar body can be a cylindrical column or a square column.

[0061] The carrier part 22 can be a spherical structure, and the spherical structure itself is provided with diffusion holes. The spherical structure and the extension part 21 are integrally formed parts, and the powder can be placed into the containing cavity 221 of the carrier part 22 from the through hole of the extension part 21.

[0062] In addition, the bearing component 22 further comprises a bearing body 222, a cover plate 223 and a fastener 224, as shown in Figure 3 The bearing body 222 is provided with a groove, as shown in Figure 3 The groove is covered by the cover plate, and cannot be shown in Figure 3 The groove is shown in the accommodating cavity 221 in Figure 2 The groove is used for filling the target powder 6 from the opening; the cover plate 223 covers the opening of the groove by the fastener 224, so that the groove forms the accommodating cavity 221; the diffusion hole is arranged on the cover plate 223. The material of the side of the cover plate 223 in contact with the target powder is an insulating material. The material of the fastener 224 can be an insulating material or not.

[0063] The fastener 224 can be at least two bolts, and the cover plate 223 is fixed by the corresponding bolt holes of the cover plate 223, so that the groove cooperates with the cover plate 223 to form the accommodating cavity 221, which can be seen in Figure 3 .

[0064] The fastener 224 can also be a hinge and at least three bolts, one side of the hinge is fixed on the cover plate 223 by at least one bolt, the other side of the hinge is fixed on the bearing body 222 by at least one bolt, and the hinge is rotated to close or open the opening of the groove, and then at least one bolt is used to fix the movable end of the cover plate 223 on the bearing body 222, so that the groove cooperates with the cover plate 223 to form the accommodating cavity 221.

[0065] The materials of the isolation part 212 and the bearing component 22 are organic materials or ceramic materials.

[0066] The isolation part 212 and the bearing component 22 can be two connected components, but it should be noted that the connection between the two components needs to be sealed to avoid the solution entering the interior of the isolation part 212 and contacting the conductive part 211. The isolation part 212 and the bearing component 22 are preferably integrally formed, which can avoid the solution entering the interior of the isolation part 212 and contacting the conductive part 211.

[0067] The inner diameter of the accommodating cavity 221 ranges from 1 mm to 20 mm. The inner diameter of the accommodating cavity 221 preferably ranges from 1 mm to 5 mm. The amount of the target powder 6 is limited by the space size of the accommodating cavity 221, that is, the maximum amount of the powder used for measuring the potential of the powder in the embodiments of the present application is the space volume of the accommodating cavity 221. For example, the accommodating cavity 221 can be a regular sphere, and the minimum inner diameter (i.e. the diameter) of the accommodating cavity 221 can be 1 mm, and the volume is about 0.5236 cubic millimeters, and the maximum volume of the powder used for the potential measurement is 0.5236 cubic millimeters. It can be seen that the amount of the powder used for the potential measurement in the embodiments of the present application is very small. Compared with the related art in which the powder is compressed into a button cell, the amount of the powder used in the embodiments of the present application is greatly reduced, and the amount of the powder is reduced, and the cost of the powder is reduced. If the powder is a newly developed rare powder, the amount of the rare powder can be greatly reduced by using the stage electrode and the method for measuring the potential provided in the embodiments of the present application, and the waste of the rare powder is reduced. In addition, the method provided in the embodiments of the present application does not damage the rare powder, which means that the powder can be reused, and the utilization rate of the rare powder can be improved.

[0068] Further, according to Figure 1 , a corresponding equivalent circuit diagram can be obtained based on the Kirchhoff's current law and the Kirchhoff's voltage law, as shown in Figure 4 , V 1-2 represents the equivalent electromotive force between the stage electrode 2 and the reference electrode 1, V 6-1 represents the equivalent electromotive force between the target powder 6 and the reference electrode 1, R 1-2 represents the equivalent resistance (i.e. the first resistance) between the stage electrode 2 and the reference electrode 1, R 6-1 represents the equivalent resistance (i.e. the second resistance) between the target powder 6 and the reference electrode 1. It should be noted that the first resistance and the second resistance can be measured in advance.

[0069] , the equivalent circuit diagram of Figure 1 is obtained. Figure 4 The principle of obtaining the equivalent circuit diagram of is that in an electrochemical system, the behavior of an electrode (such as a working electrode or a counter electrode) can be analogous to an active element in a circuit, and the characteristics include a potential difference and a resistance characteristic. The potential difference refers to the inherent electrochemical potential (similar to a voltage source) at the interface between the electrode and the electrolyte 4. The resistance characteristic refers to the resistance of charge transfer and ion diffusion (similar to a resistor). Therefore, the equivalent circuit model of the electrode is usually represented as a combination of a voltage source (electromotive force) and an internal resistance (charge transfer resistance, solution resistance, etc.).

[0070] Specifically, regarding the voltage element (voltage source), that is, V Figure 4 in6-1 and V 1-2 When the electrode material is in contact with the electrolyte 4, a certain potential difference will be formed spontaneously due to the tendency of redox reaction, similar to the open circuit voltage (electromotive force) of a battery. If the electrode tends to oxidize (lose electrons), the polarity of the equivalent voltage source is negative to the electrolyte 4; if it tends to reduce (gain electrons), the opposite is true.

[0071] Regarding the resistance element, it can be divided into several categories, such as the resistance of electrons crossing the interface when the electrode surface undergoes an electrochemical reaction (related to reaction kinetics). The resistance caused by the insufficient ion conductivity of the electrolyte 4 (related to the concentration and temperature of the electrolyte 4). The additional resistance caused by the concentration gradient of the reactants.

[0072] Based on Kirchhoff's current law and Kirchhoff's voltage law, the sum of the voltages in the potential detection system is 0, and according to the direction of ion flow, the following formula 1 can be obtained.

[0073] Formula 1 Wherein, represents the potential change between the electrolyte 4 and the reference electrode 1. represents the potential change between the target powder 6 and the electrolyte 4. represents the potential change between the electrolyte 4 and the stage electrode 2, specifically the potential change between the electrolyte 4 and the insulating part (including the bearing part 22 and the isolation part 212) of the stage electrode 2, represents the potential change between the reference electrode 1 and the electrolyte 4. It should be noted that the potential change is a vector and has directionality. represents the potential change between the target powder 6 and the reference electrode 1. Figure 4 represents the current in the series circuit composed of V 1-2 , R 1-2 , R 6-1 , V 6-1 . represents the equivalent resistance (i.e. the second resistance) between the target powder 6 and the reference electrode 1, which can also be represented by R 6-1 . represents the equivalent resistance (i.e. the first resistance) between the insulating part (including the bearing part 22 and the isolation part 212) of the stage electrode 2 and the reference electrode 1, which can also be represented by R 1-2 .

[0074] According to and , the voltage value between the target powder 6 and the reference electrode 1 can be determined, which can be represented by , which can be seen from the following formula.

[0075]

[0076] according to and The voltage value between the insulating portion (including the carrier component 22 and the isolation portion 212) of the reference electrode 1 and the stage electrode 2 can be determined, and can be used... For details, please refer to the following formula.

[0077]

[0078] Therefore, Formula 1 above can also be transformed into Formula 2.

[0079] Formula 2 By transforming Formula 2 as follows, we can obtain Formula 3.

[0080]

[0081]

[0082] Formula 3 Furthermore, according to Figure 4 Chinese R 6-1 V 6-1 The relationship between the voltage, current, and resistance of the branch can be expressed by the following formula 4. Figure 4 The upper and lower branches on the left side are the two measuring terminals of voltage measuring device 5.

[0083] Formula 4 in, This indicates the voltage value displayed by voltage measuring device 5.

[0084] Then, substituting Formula 3 into Formula 4, we can obtain the following Formula 5.

[0085] Formula 5 The ultimate goal of this application embodiment is to obtain the potential of the target powder 6 relative to the reference electrode 1. Therefore, each voltage difference (i.e., V) can be converted into two associated potentials (i.e., ... Figure 4 Based on the relationship between formulas 5 and 6, we can obtain the following formula 6.

[0086] Formula 6 Simplifying formula 6, we can obtain formula 7 as follows.

[0087] Formula 7 Then, by further transforming formula 7, we can obtain the following formula 8.

[0088] Equation 8 As can be seen from Equation 8, when the potential detection system according to the embodiments of the present application is used to measure the potential of the target powder 6, two types of error terms will be introduced. One of the error terms is the potential difference between the target powder 6 and the insulated part of the carrier electrode 2, that is, the part of Equation 8 This part. The other error term is the equivalent resistance between the reference electrode 1 and the target powder 6, and the equivalent resistance between the reference electrode 1 and the insulated part of the carrier electrode 2 (including the bearing part 22 and the isolation part 212), that is, the part of Equation 8 This part.

[0089] Based on the two types of error terms in Equation 8, the following conclusions can be drawn: Conclusion 1: The equivalent resistance between the reference electrode 1 and the insulated part of the carrier electrode 2 (including the bearing part 22 and the isolation part 212) is much larger than the equivalent resistance between the reference electrode 1 and the target powder 6, which can make the error caused by the resistance error term lower.

[0090] Conclusion 2: The smaller the difference between the potential of the target powder 6 (also referred to as the potential) and the potential of the insulated part of the carrier electrode 2 (including the bearing part 22 and the isolation part 212), that is, the closer the potential of the target powder 6 is to the potential of the insulated part of the carrier electrode 2 (including the bearing part 22 and the isolation part 212), the lower the error caused by the potential difference error term. In the most ideal case, the potential of the target powder 6 is equal to the potential of the insulated part of the carrier electrode 2, which can eliminate the potential difference error term and the resistance error term.

[0091] However, the potential difference error term and the resistance error term cannot be eliminated, but only the error values of the potential difference error term and the resistance error term can be made as low as possible, so that the potential of the target powder 6 measured is more accurate. Therefore, according to the above Conclusion 1 and Conclusion 2, the reference electrode 1 and the insulated part of the carrier electrode 2 (including the bearing part 22 and the isolation part 212) can be selected to improve the accuracy of the potential measurement of the target powder 6 as much as possible.

[0092] The resistance is equal to the resistivity multiplied by the distance and divided by the surface area, that is, when the surface area of the containing cavity 221 in the carrier electrode 2 is smaller, the corresponding resistance value is larger, which can make the equivalent resistance between the reference electrode 1 and the insulated part of the carrier electrode 2 (including the bearing part 22 and the isolation part 212) much larger than the equivalent resistance between the reference electrode 1 and the target powder 6, so that the error caused by the resistance error term is lower. The resistivity is a characteristic of the electrolyte.

[0093] Further, based on the above potential detection system, the embodiments of the present application provide a potential detection system as shown inFigure 5 A potential measurement method is shown, the potential measurement method comprising: Step S51, the target powder 6 to be measured is added to the accommodating cavity 221 of the carrier electrode 2; Step S52, the accommodating cavity 221 is completely immersed in the electrolyte 4 contained in the container 3; one end of the reference electrode 1 is immersed in the electrolyte 4; Step S53, one measurement end of the voltage measurer 5 is connected with the conductive part 211, and the other measurement end of the voltage measurer 5 is connected with the other end of the reference electrode 1; Step S54, a first voltage value displayed by the voltage measurer 5 is collected; Step S55, based on the Kirchhoff's law and the first voltage value, the actual potential of the target powder 6 is determined.

[0094] In some embodiments of the present application, based on the foregoing scheme, before the target powder 6 to be measured is added to the accommodating cavity 221 of the carrier electrode 2, the potential measurement method further comprises: calibrating the potential of the reference electrode 1. That is, it is determined whether the potential of the reference electrode 1 has changed, and if it has changed compared with the last detected potential, the potential of the reference electrode 1 needs to be determined again.

[0095] Calibrating the potential of the reference electrode 1 is a key step in electrochemical testing, which needs to be compared with a standard hydrogen electrode or a secondary standard electrode. The calibration principle is that the potential of the reference electrode 1 is essentially the potential difference of the reference electrode 1 relative to the standard hydrogen electrode (defined as 0V). Common calibration methods include direct method and indirect method. The direct method refers to direct comparison with the standard hydrogen electrode (laboratory high-precision requirement), and the indirect method refers to transmission through the secondary standard electrode (such as saturated calomel electrode).

[0096] In some embodiments of the present application, based on the foregoing scheme, before the target powder 6 to be measured is added to the accommodating cavity 221 of the carrier electrode 2, after calibrating the potential of the reference electrode 1, the potential measurement method further comprises: A reference powder with a reference potential is added to the accommodating cavity 221; the reference powder can be any powder with a known potential.

[0097] The accommodating cavity 221 is completely immersed in the electrolyte 4; one end of the reference electrode 1 is immersed in the electrolyte 4; One measurement end of the voltage measurer 5 is connected with the conductive part 211, and the other measurement end of the voltage measurer 5 is connected with the other end of the reference electrode 1; collecting a second voltage value displayed by the voltage measurer 5; determining a measured potential of the reference powder based on the Kirchhoff's law and the second voltage value; determining an accuracy threshold value for characterizing the potential measurement accuracy of the potential detection system according to the measured potential and the reference potential; measuring the potential of the target powder 6 to be measured again in a case where the accuracy threshold value meets a preset accuracy requirement.

[0098] In some embodiments of the present application, based on the foregoing scheme, after the accommodating cavity 221 is completely immersed in the electrolyte 4 contained in the container 3, before the first voltage value displayed by the voltage measurer 5 is collected, the method further comprises: The duration for which the accommodating cavity 221 is completely immersed in the electrolyte 4 reaches a preset duration, and the preset duration is a duration greater than or equal to 30 seconds. The preset duration can be 60 seconds in particular.

[0099] It should be noted that the potential of the reference powder is measured before the potential of the target powder 6 is measured. In actual operation, the process of measuring the potential of the reference powder is the same as the process of measuring the potential of the target powder 6, so after the potential of the reference powder is measured and the accuracy threshold value meets the preset accuracy requirement, the reference powder can be replaced with the target powder only, without the need to reassemble the potential detection system, which can improve the potential detection efficiency.

[0100] On the basis of the foregoing scheme provided by the embodiments of the present application, a specific example is now provided to verify the accuracy of the potential measurement of the target powder 6 provided by the embodiments of the present application.

[0101] Two standard sample powders are now selected for testing, and the two sample powders are a graphite negative electrode with 50% SOC and a graphite negative electrode with 90% SOC. The standard potential U of the graphite negative electrode with 50% SOC is 140 mV. The standard potential U of the graphite negative electrode with 90% SOC is 90.00 mV.

[0102] The embodiments of the present application also provide two different reference electrodes 1. One reference electrode 1 is a 50% SOC lithium iron phosphate (LFP for short), and the standard potential U thereof is 3.414 V. The other reference electrode 1 is a lithium metal sheet, and the standard potential U thereof is 0 V.

[0103] The embodiments of the present application also provide three different sizes of the carrier electrode 2, which are 1.5 mm, 5 mm, and 20 mm respectively. It should be noted that the size here refers to the inner diameter of the accommodating cavity 221.

[0104] Based on the different standard samples, reference electrode 1 and carrier electrode 2 provided above, four examples can be obtained by combining them. The potential measurement method of the powder provided in the embodiment of the present application is used to measure the four examples respectively, and the contents shown in Table 1 can be obtained.

[0105] Table 1

[0106] As can be seen from Table 1, the potentials of the graphite detected in Example 1 and Example 3 are not much different from the reference potential. For example, for Example 1, the graphite with 50% SOC, the reference electrode 1 of LFP with 50% SOC and the carrier electrode 2 of 1.5 mm, the measured potential is 139.35 mV, which is 0.65 mV different from the standard potential U=140 mV, and the two are similar. The graphite with 90% SOC, the reference electrode 1 of LFP with 50% SOC and the carrier electrode 2 of 1.5 mm, the measured potential is 89.61 mV, which is 0.39 mV different from the standard potential U=90 mV, and the two are similar.

[0107] For Example 3, the graphite with 50% SOC, the reference electrode 1 of lithium metal sheet and the carrier electrode 2 of 1.5 mm, the measured potential is 139.21 mV, which is 0.79 mV different from the standard potential U=140 mV, and the two are similar. The graphite with 90% SOC, the reference electrode 1 of lithium metal sheet and the carrier electrode 2 of 1.5 mm, the measured potential is 89.2 mV, which is 0.8 mV different from the standard potential U=90 mV, and the two are similar.

[0108] As can be seen from Example 1 and Example 3, the LFP with 50% SOC and the lithium metal sheet as the reference electrode 1, the accuracy of the finally detected potential of the powder is high.

[0109] As can be seen from Table 1, the potentials of the graphite detected in Example 2 and Example 4 are relatively large different from the reference potential. For Example 2, the graphite with 50% SOC, the reference electrode 1 of LFP with 50% SOC and the carrier electrode 2 of 5 mm, the measured potential is 130.58 mV, which is 9.42 mV different from the standard potential U=140 mV, which is relatively large, and the accuracy is low. The graphite with 90% SOC, the reference electrode 1 of LFP with 50% SOC and the carrier electrode 2 of 5 mm, the measured potential is 89.61 mV, which is 4.65 mV different from the standard potential U=90 mV, which is relatively large, and the accuracy is low.

[0110] Comparing Example 1 with Example 2, the difference is that the size of the carrier electrode 2 is different, and the accuracy of the measured potential in Example 2 is lower. Such a comparative example can support the aforementioned inference of the embodiments of the present application: the smaller the volume of the carrier electrode 2, the higher the accuracy of the detected potential.

[0111] For Example 4, the measured potential of the graphite at 50% SOC, the reference electrode 1 of LFP at 50% SOC, and the carrier electrode 2 of 20 mm is 158.46 mV, which is 18.46 mV different from the standard potential U=140 mV, and the difference is large and the accuracy is low. The measured potential of the graphite at 90% SOC, the reference electrode 1 of LFP at 50% SOC, and the carrier electrode 2 of 20 mm is 109.35 mV, which is 19.35 mV different from the standard potential U=90 mV, and the difference is large and the accuracy is low.

[0112] Comparing Example 1 with Example 4, the difference is that the size of the carrier electrode 2 is different, and the accuracy of the measured potential in Example 4 is lower. Such a comparative example can support the aforementioned inference of the embodiments of the present application: the smaller the volume of the carrier electrode 2, the higher the accuracy of the detected potential.

[0113] Further, comparing Example 2 with Example 4, the difference is that the size of the carrier electrode 2 is different, and the accuracy of the measured potential in Example 4 is lower. Such a comparative example can support the aforementioned inference of the embodiments of the present application: the smaller the volume of the carrier electrode 2, the higher the accuracy of the detected potential.

[0114] In summary, the embodiment of the present application provides a carrier electrode, the carrier electrode 2 comprises an extension component 21 and a bearing component 22; the extension component 21 comprises a conductive part 211 and an isolation part 212 wrapped outside the conductive part 211; the isolation part 212 is connected with the bearing component 22; the materials of the isolation part 212 and the bearing component 22 are insulating materials; the isolation part 212 is used to isolate the conductive part 211 and the electrolyte 4 when the potential detection system detects the potential of the target powder 6; the bearing component 22 is internally arranged with a containing cavity 221, the containing cavity 221 is used to contain the target powder 6, and the conductive part 211 extends into the containing cavity 221 to contact the target powder 6 when the potential detection system detects the potential of the target powder 6; the bearing component 22 is provided with a diffusion hole, the diffusion hole is communicated with the containing cavity 221, so that the ion diffusion between the target powder 6 and the electrolyte 4 is realized when the potential detection system detects the potential of the target powder 6. It can be seen that in the embodiment of the present application, the potential of the powder coated on the surface of the battery electrode can be measured without compressing the powder into a button cell, and then the powder can not be damaged, so that the recycling rate of the powder can be improved. Further, since the embodiment of the present application does not need to compress the powder into a button cell, the amount of powder required is smaller, that is, the potential of the trace powder can be measured, which can reduce the amount of powder used for measuring the potential and save the cost of powder potential measurement.

[0115] Further, the embodiment of the present application measures the potential of the powder without using pulse signals such as electrical signals and laser signals, so that the state of the powder material can be avoided to be changed by the two kinds of signals, the introduction of error items is reduced, and the measurement result is more accurate. In addition, the embodiment of the present application measures the potential of the powder in the state that the powder and the battery cell are independent of each other, so that the battery cell does not need to be charged to different states to disassemble and test the local voltage. In this way, the iron lithium, ternary or graphite is in the same lithium intercalation state and belongs to the equilibrium state, which ensures the measurement accuracy of the potential of the powder.

[0116] Based on the same inventive concept, the embodiment of the present application provides a battery electrode sheet surface uniformity detection method as shown in Figure 6 The detection method comprises: Step S61, the powder coated on the surface of the target battery electrode sheet in at least two different regions is scraped off, and the actual potential of the powder in each region is obtained by using the potential measurement method provided in the foregoing embodiment of the present application respectively; In step S62, a determination result characterizing the uniformity of the material coated on the surface of the target battery pole piece is determined according to the actual potentials of the respective regions. If the difference between the actual potentials of the respective regions is within the preset difference range, it is considered that the powder material coated on the surface of the target battery pole piece is uniform. If the difference between the actual potentials of any two regions is not within the preset difference range, it is considered that the powder material coated on at least one of the two regions is non-uniform.

[0117] In some embodiments of the present application, based on the foregoing scheme, the detection method further comprises: In the case where the determination result characterizes that the material coated on the surface of the target battery pole piece is non-uniform, the content of the powder of the respective regions is adjusted according to the difference between the actual potentials of the respective regions, and a battery pole piece of the same type as the target battery pole piece is re-produced so that the material coated on the surface of the re-produced battery pole piece meets the uniformity requirement.

[0118] In summary, in the embodiments of the present application, the powder coated on at least two different regions of the surface of the target battery pole piece is scraped off, and the actual potential of the powder of each region is obtained by using the foregoing potential measurement method provided in the embodiments of the present application. A determination result characterizing the uniformity of the material coated on the surface of the target battery pole piece is determined according to the actual potentials of the respective regions. It can be seen that, in the embodiments of the present application, the uniformity of the powder material coated on the surface of the battery pole piece can be determined by measuring the potential of the powder coated on each region of the surface of the battery pole piece, so as to verify whether the produced battery pole piece is qualified, thereby improving the production quality and consistency of the battery pole piece. In this way, the various non-uniformities of the positive and negative pole pieces leaving the factory can be minimized, such as the non-uniformity of the particle size distribution of the raw material, the non-uniformity of the particle distribution and stress state in the slurry mixing, coating and rolling processes, and the non-uniformity of the structure of the battery cell in the local temperature rise during charging and discharging, thereby reducing the probability of occurrence of local purple stains or lithium precipitation and improving the use safety and service life of the battery.

[0119] Further, in the embodiments of the present application, the uniformity of the powder material coated on the surface of the battery pole piece can be determined by measuring the potential of the powder coated on each region of the surface of the battery pole piece, which can be applied in the research and development process of new battery pole pieces, such as crimped pole pieces, so as to adjust the content of the powder material of each different crimped region of the battery pole piece, thereby improving the charging and discharging performance of the battery pole piece and shortening the development cycle of the new battery pole piece.

[0120] Based on the same inventive concept, the embodiments of the present application provide a battery pole piece quality detection method as shown in Figure 7 The detection method comprises the following steps. Step S71, selecting at least two battery pole pieces respectively as target battery pole pieces from the same batch of battery pole pieces produced using the same production parameters, and determining a determination result characterizing the uniformity of the material coated on the surface of each of the target battery pole pieces by using the battery pole piece surface uniformity detection method provided in the foregoing embodiments of the present application; Step S72, determining whether the quality of the battery pole pieces of the batch is qualified according to the determination result of each of the target battery pole pieces.

[0121] In some embodiments of the present application, based on the foregoing scheme, the method further comprises: In the case where it is determined that the quality of the battery pole pieces of the batch is unqualified, the production parameters of the battery pole pieces of the batch are adjusted and optimized, and the battery pole pieces are re-produced by using the adjusted and optimized production parameters, so that the re-produced battery pole pieces are qualified.

[0122] In summary, in the embodiments of the present application, at least two battery pole pieces are selected respectively as target battery pole pieces from the same batch of battery pole pieces produced using the same production parameters, and a determination result characterizing the uniformity of the material coated on the surface of each of the target battery pole pieces is determined by using the battery pole piece surface uniformity detection method provided in the foregoing embodiments of the present application; whether the quality of the battery pole pieces of the batch is qualified is determined according to the determination result of each of the target battery pole pieces. It can be seen that the embodiments of the present application can measure whether the powder coated on each region of the surface of the battery pole pieces produced in the current batch is uniform by sampling detection on the battery pole pieces produced in the same batch, so as to check whether the battery pole pieces produced in the current batch are qualified. If the battery pole pieces produced in the current batch are generally unqualified, it means that the production parameters are abnormal, and the production parameters need to be adjusted, so that the production quality and consistency of the battery pole pieces can be improved. In this way, various non-uniformities of the produced positive and negative pole pieces can be reduced as much as possible, such as non-uniformity of the particle size distribution of the raw material, non-uniformity of the particle distribution and stress state in the slurry mixing, coating and rolling processes, and non-uniformity of the structure of the battery cell in the local temperature rise during charging and discharging, thereby reducing the probability of occurrence of local purple stains or lithium precipitation, and improving the use safety and service life of the battery.

[0123] Since the electronic device introduced in the embodiments of the present application is the electronic device used to implement the information processing method in the embodiments of the present application, the specific implementation of the electronic device and its various forms can be understood by those skilled in the art based on the information processing method introduced in the embodiments of the present application, so the detailed introduction of how the electronic device implements the method in the embodiments of the present application is not given here. As long as the electronic device used to implement the information processing method in the embodiments of the present application is implemented by those skilled in the art, it belongs to the scope of protection of the present application.

[0124] The technical solutions in the embodiments of the present application have at least the following technical effects or advantages: The embodiment of the present application first provides a carrier electrode, the carrier electrode 2 includes an extension component 21 and a bearing component 22; the extension component 21 includes a conductive part 211 and an isolation part 212 wrapped outside the conductive part 211; the isolation part 212 is connected with the bearing component 22; the materials of the isolation part 212 and the bearing component 22 are insulating materials; the isolation part 212 is used to isolate the conductive part 211 and the electrolyte 4 when the potential detection system detects the potential of the target powder 6; the bearing component 22 is internally arranged with a containing cavity 221, the containing cavity 221 is used to contain the target powder 6, and the conductive part 211 extends into the containing cavity 221 to contact the target powder 6 when the potential detection system detects the potential of the target powder 6; the bearing component 22 is provided with a diffusion hole, the diffusion hole is in communication with the containing cavity 221, so that ion diffusion between the target powder 6 and the electrolyte 4 is realized when the potential detection system detects the potential of the target powder 6. Then on this basis, a potential detection system is provided, the detection system includes: a reference electrode 1, an electrolyte 4, a voltage measurer 5, a container 3 and a carrier electrode 2; one end of the reference electrode 1 is placed in the electrolyte 4 contained in the container 3, and the containing cavity 221 in the carrier electrode 2 for containing the target powder 6 is placed in the electrolyte 4; one measurement end of the voltage measurer 5 is connected with the other end of the reference electrode 1, and the other measurement end of the voltage measurer 5 is connected with the conductive part 211 of the carrier electrode 2, and then the potential of the target powder 6 is determined based on Kirchhoff's law and the voltage measurement value of the voltage measurer 5.

[0125] In the embodiment of the present application, the potential of the powder coated on the surface of the battery electrode can be measured without compressing the powder into a button cell, and then the powder can not be damaged, so that the reuse rate of the powder can be improved. Further, since the powder does not need to be compressed into a button cell in the embodiment of the present application, the amount of powder required is smaller, that is, the potential of the trace amount of powder can be measured, which can reduce the amount of powder used for measuring the potential and save the cost of powder potential measurement.

[0126] The potential of the powder is measured by the embodiment of the present application without using pulse signals such as electrical signals and laser signals, so that the state of the powder material is avoided to be changed by the two signals, the introduction of error terms is reduced, and the measurement result is more accurate. In addition, the potential of the powder is measured by the embodiment of the present application in the state that the powder and the battery cell are independent of each other, so that the battery cell does not need to be charged to different states to disassemble and test the local voltage. In this way, the lithium-iron, ternary or graphite is in the same lithium intercalation state, which belongs to the equilibrium state, and the measurement accuracy of the potential of the powder is ensured.

[0127] The powder coated on at least two different regions of the surface of the target battery pole piece is scraped off by the embodiment of the present application, and the actual potential of the powder in each region is obtained by using the aforementioned potential measurement method provided by the embodiment of the present application. According to the actual potential of each region, a determination result is determined to characterize the uniformity of the material coated on the surface of the target battery pole piece. It can be seen that the embodiment of the present application can determine whether the powder material coated on the surface of the battery pole piece is uniform by measuring the potential of the powder coated on each region of the surface of the battery pole piece, so as to check whether the produced battery pole piece is qualified, so as to improve the production quality and quality consistency of the battery pole piece. In this way, the various non-uniformities of the positive and negative pole pieces leaving the factory can be minimized, such as the non-uniformity of the particle size distribution of the raw material, the non-uniformity of the particle distribution and stress state in the slurry mixing, coating and rolling process, and the non-uniformity of the structure of the battery cell in the local temperature rise during charging and discharging process, and the like. In this way, the occurrence probability of local purple spots or lithium precipitation phenomenon can be reduced, and the use safety and service life of the battery can be improved. The embodiment of the present application can be applied in the research and development process of new battery pole pieces, such as crimped pole pieces, so as to adjust the content of the powder material in each different crimped region of the battery pole piece, and improve the charging and discharging performance of the battery pole piece, and shorten the development cycle of the new battery pole piece.

[0128] The embodiments of the present application select at least two battery pole pieces from the same batch of battery pole pieces produced using the same production parameters as target battery pole pieces, respectively, determine a determination result characterizing the uniformity of the material coated on the surface of each target battery pole piece by using the battery pole piece surface uniformity detection method provided in the foregoing of the embodiments of the present application, and determine whether the quality of the battery pole pieces of the batch is qualified according to the determination result of each target battery pole piece. It can be seen that the embodiments of the present application can perform sampling detection on the battery pole pieces produced in the same batch to measure whether the powder coated on each region of the surface of the battery pole pieces produced in the current batch is uniform, so as to verify whether the battery pole pieces produced in the current batch are qualified. If the battery pole pieces produced in the current batch are generally unqualified, it means that the production parameters are abnormal, and the production parameters need to be adjusted, so that the production quality and quality consistency of the battery pole pieces can be improved. In this way, various non-uniformities of the positive and negative pole pieces produced can be reduced as much as possible, for example, due to the non-uniformity of the particle size distribution of the raw materials, the non-uniformity of the particle distribution and stress state in the slurry mixing, coating and rolling processes, and the non-uniformity of the temperature rise of the structure of the battery cell in the charging and discharging process, and so on, so that the occurrence probability of the local purple stain or lithium precipitation phenomenon can be reduced, and the use safety and service life of the battery can be improved.

[0129] Although preferred embodiments of the application have been described, those skilled in the art will be able to make additional changes and modifications without departing from the spirit and scope of the application. Therefore, the appended claims are intended to cover all such changes and modifications that fall within the scope of the application.

[0130] Obviously, various modifications and changes can be made to the present application by those skilled in the art without departing from the spirit and scope of the present application. Thus, it is intended that the present application cover the modifications and changes as they fall within the scope of the claims and their equivalents.

Claims

1. A carrier electrode, characterized by, The application is applied to a potential detection system including electrolyte, and is used for detecting the potential of target powder. The carrier electrode comprises an extension component and a bearing component; the extension component comprises a conductive part and an isolation part wrapped outside the conductive part; the isolation part is connected with the bearing component; the isolation part and the bearing component are made of insulating material; the isolation part is used for isolating the conductive part and the electrolyte when the potential detection system detects the potential of the target powder. The bearing component is internally arranged with a containing cavity used for containing the target powder, and the conductive part extends to the containing cavity to contact with the target powder when the potential detection system detects the potential of the target powder. The bearing component is provided with diffusion holes which are communicated with the containing cavity to realize ion diffusion between the target powder and the electrolyte when the potential detection system detects the potential of the target powder.

2. A carrier electrode as claimed in claim 1, characterized in that The bearing component comprises a bearing body, a cover plate and a fastener; the bearing body is arranged with a groove used for adding the target powder from an opening; the cover plate covers the opening of the groove by the fastener to make the groove form the containing cavity; and the diffusion holes are arranged on the cover plate.

3. A carrier electrode as claimed in claim 1, wherein The isolation part and the bearing component are made of organic material or ceramic material.

4. The carrier electrode of claim 1, wherein The isolation part and the bearing component are integrally formed.

5. The carrier electrode of claim 1, wherein The inner diameter of the containing cavity ranges from 1mm to 20mm.

6. A carrier electrode as claimed in claim 1, wherein The inner diameter of the containing cavity ranges from 1mm to 5mm.

7. A potential detection system characterized by, The detection system is used for detecting the potential of target powder, and comprises a reference electrode, electrolyte, a voltage measurer, a container and the carrier electrode as claimed in any one of claims 1-6. One end of the reference electrode is placed in the electrolyte in the container, and the containing cavity in the carrier electrode used for containing the target powder is placed in the electrolyte. One measuring end of the voltage measurer is connected with the other end of the reference electrode, and the other measuring end of the voltage measurer is connected with the conductive part of the carrier electrode, so as to determine the potential of the target powder based on Kirchhoff's law and the voltage measurement value of the voltage measurer.

8. A potential detection system as claimed in claim 7, characterised in that, The reference electrode is a lithium metal sheet, a copper-lithium composite foil or a lithium iron phosphate positive electrode sheet with a preset lithium ion deintercalation ratio.

9. A potential detection system as claimed in claim 7, wherein, The electrolyte is the electrolyte of a lithium battery.

10. A potential detection system as claimed in claim 7, wherein, The measurement resolution of the voltage measurer is 0.00001V.

11. A potential detection system as claimed in claim 7, wherein, The container is made of one of quartz glass, polytetrafluoroethylene and expanded glass.

12. A potential detection system as claimed in claim 7, characterized in that The equivalent resistance between the reference electrode and the carrier electrode is a first resistance, and the equivalent resistance between the reference electrode and the target powder is a second resistance, and the resistance value of the first resistance is greater than that of the second resistance.

13. A method of measuring potential, characterized by, The potential detection method is suitable for the potential detection system as claimed in any one of claims 7-12, and comprises: adding the target powder to be measured into the containing cavity of the carrier electrode; immersing the accommodating cavity into the electrolyte in the container completely; and immersing one end of the reference electrode into the electrolyte; connecting one measurement end of the voltage measurer with the conductive part, and connecting the other measurement end of the voltage measurer with the other end of the reference electrode; collecting a first voltage value displayed by the voltage measurer; determining an actual potential of the target powder based on the first voltage value and the Kirchhoff's law.

14. A method of measuring potential as claimed in claim 13, wherein, Before the target powder to be measured is added into the accommodating cavity of the carrier electrode, the potential measurement method further comprises: calibrating the potential of the reference electrode.

15. A method of measuring potential as claimed in claim 14, wherein, Before the target powder to be measured is added into the accommodating cavity of the carrier electrode, after the potential of the reference electrode is calibrated, the potential measurement method further comprises: adding a reference powder with a reference potential into the accommodating cavity; immersing the accommodating cavity into the electrolyte completely; and immersing one end of the reference electrode into the electrolyte; connecting one measurement end of the voltage measurer with the conductive part, and connecting the other measurement end of the voltage measurer with the other end of the reference electrode; collecting a second voltage value displayed by the voltage measurer; determining a measurement potential of the reference powder based on the second voltage value and the Kirchhoff's law; determining an accuracy threshold value representing the accuracy of the potential measurement of the potential detection system according to the measurement potential and the reference potential; measuring the potential of the target powder to be measured again in a case where the accuracy threshold value meets a preset accuracy requirement.

16. A method of measuring potential as defined in claim 13, wherein After the accommodating cavity is immersed into the electrolyte in the container completely, before the first voltage value displayed by the voltage measurer is collected, the method further comprises: The duration of the accommodating cavity being immersed into the electrolyte completely reaches a preset duration, and the preset duration is a duration greater than or equal to 30 seconds.

17. A method for detecting the surface uniformity of battery electrode sheets, characterized in that, The detection method comprises: scraping off the powder coated on at least two different regions of the surface of the target battery electrode sheet respectively, and obtaining actual potentials of the powder in each region by using any one of the potential measurement methods in claims 13-16; determining a determination result representing the uniformity of the material coated on the surface of the target battery electrode sheet according to the actual potentials of the regions.

18. The method for detecting the surface uniformity of battery electrode sheets as described in claim 17, characterized in that, The detection method further comprises: in a case where the determination result represents that the material coated on the surface of the target battery electrode sheet is not uniform, adjusting the content of the powder in each region according to the difference between the actual potentials of the regions, and re-producing a battery electrode sheet of the same type as the target battery electrode sheet so that the material coated on the surface of the re-produced battery electrode sheet meets the uniformity requirement.

19. A method for inspecting the quality of battery electrodes, characterized in that, The detection method comprises: selecting at least two battery electrode sheets from the same batch of battery electrode sheets produced by using the same production parameters as the target battery electrode sheets, and determining a determination result representing the uniformity of the material coated on the surface of each target battery electrode sheet by using any one of the battery electrode sheet surface uniformity detection methods in claims 17-18; According to the determination result of each target battery pole piece, it is determined whether the quality of the batch of battery pole pieces is qualified.

20. A method of battery electrode sheet quality inspection as claimed in claim 19, wherein, The method further comprises: In the case where it is determined that the quality of the batch of battery pole pieces is unqualified, the production parameters of the batch of battery pole pieces are adjusted and optimized, and the battery pole pieces are re-produced by using the adjusted and optimized production parameters, so that the quality of the re-produced battery pole pieces is qualified.

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