Device and method for measuring electrode potential of electrode piece

Abstract

The present invention provides an electrode potential measurement device and method for an electrode piece, the device comprising: a stage, a reference electrode probe, a first drive unit and a second drive unit; wherein the stage is used to carry the electrode piece to be measured; the reference electrode probe is used to contact the electrode piece to be measured to measure the electrode potential of the area in the electrode piece to be measured where the reference electrode probe contacts; the first drive unit is connected to the reference electrode probe to drive the reference electrode probe to reciprocate in a direction perpendicular to the electrode piece to be measured; the second drive unit is used to drive the first drive unit or the stage to move so that the reference electrode probe covers at least part of the surface of the electrode piece to be measured. The present invention realizes large-area electrode potential measurement of the electrode piece through the electrode potential measurement device, thereby characterizing the lithium concentration distribution of the electrode piece over a large range, and further realizing the judgment of the electrochemical reaction process of the electrode piece.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium batteries, and in particular relates to a device for measuring the electrode potential of a pole piece and a method for measuring the electrode potential of a pole piece. Background Art

[0002] Lithium ions are embedded and extracted from positive and negative electrode materials during the charge and discharge process. The lithium ion concentration distribution is directly related to the charge state of the electrode, and is also closely related to the stress and strain when the electrode expands / contracts. By characterizing the lithium concentration distribution of the electrode, a lot of important information related to the electrode reaction can be obtained, such as the charge and discharge process, failure analysis, etc. Over-compaction of the electrode, insufficient electrolyte infiltration, or some internal defects such as agglomeration, foreign matter, bubbles, etc. will also significantly affect the lithium concentration distribution in the corresponding area. Researchers have been able to observe or detect the lithium concentration distribution of activated electrode sheets in a variety of ways, such as judging the degree of lithium insertion by the color change of the graphite electrode. The color changes from the initial dark gray to dark blue and red, and finally all changes to gold. Optical microscopy can help make more refined judgments, and there are human biases in the color judgment method. More advanced in-situ analysis techniques such as neutron diffraction, X-ray diffraction, Raman spectroscopy, etc. are used to detect the degree of lithium insertion and lithium precipitation. These methods generally analyze the cross-section of the electrode by imaging, and cannot fully explain the lithium distribution of the entire electrode. Disassembling the battery cell to analyze the abnormal area of ​​the entire electrode is a simple method, and human judgment is still unable to make a quantitative analysis; transferring the disassembled electrode via a vacuum transfer box to a scanning electron microscope to look for the special morphology of lithium dendrites is also a common detection method. The disadvantage of the electron microscope observation method is that it is difficult to detect large-area electrodes.

[0003] In summary, the existing methods for detecting the lithium concentration distribution of the electrode have the following shortcomings:

[0004] Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an electrode potential measuring device and an electrode potential measuring method for an electrode piece, so as to characterize the lithium concentration distribution of a large range of the electrode piece by measuring the electrode potential of a large area of ​​the electrode piece, and then realize the judgment of the electrochemical reaction process of the electrode piece.

[0006] In order to solve or improve the above technical problems to a certain extent, according to one aspect of the present invention, there is provided an electrode potential measuring device for a pole piece, comprising: a stage, a reference electrode probe, a first driving part and a second driving part;

[0007] Wherein, the stage is used to carry the pole piece to be tested;

[0008] The reference electrode probe is used to contact the electrode piece to be tested, so as to measure the electrode potential of the area in the electrode piece to be tested where the reference electrode probe contacts;

[0009] The first driving unit is connected to the reference electrode probe, and drives the reference electrode probe to reciprocate in a direction perpendicular to the electrode piece to be tested;

[0010] The second driving unit is used to drive the first driving unit or the stage to move so that the reference electrode probe covers at least a portion of the surface of the electrode piece to be tested.

[0011] In some embodiments, the reference electrode probe comprises a probe housing, a reference electrode, and a diaphragm;

[0012] Wherein, the reference electrode is arranged in the probe housing, and the probe housing stores an electrolyte;

[0013] An opening is provided at one end of the probe housing, and the diaphragm covers the opening. When the first driving unit drives the reference electrode probe to contact the electrode to be measured, the reference electrode contacts one side of the diaphragm, and the other side of the diaphragm contacts the electrode to be measured.

[0014] In some embodiments, the probe housing includes a first shell and a second shell;

[0015] Wherein, the reference electrode is inserted into the first shell, and the second shell is slidably mounted on one end of the first shell;

[0016] An elastic member is disposed in the first shell and the second shell, and two ends of the elastic member abut against the first shell and the second shell respectively;

[0017] The opening is arranged on one end of the second shell away from the first shell. When driven by the first driving unit, the first shell compresses the elastic member, and one end of the reference electrode contacts the one side of the diaphragm.

[0018] In some embodiments, the diaphragm is disposed on an outer side of the one end of the second shell.

[0019] In some embodiments, a liquid injection hole is provided on the first shell.

[0020] In some embodiments, the first driving unit includes a Z-axis guide unit and a first driver, and the second driving unit includes a first X-axis guide unit, a first Y-axis guide unit, a second driver, and a third driver;

[0021] The reference electrode probe and the first driver are arranged on the Z-axis guide unit, and the first driver is connected to the reference electrode probe to drive the reference electrode probe to reciprocate in a direction perpendicular to the electrode piece to be tested;

[0022] The Z-axis guide unit is connected to the first X-axis guide unit, and the second driver is disposed on the Z-axis guide unit or the first X-axis guide unit to drive the Z-axis guide unit to move along the first X-axis guide unit;

[0023] The first X-axis guide unit is connected to the first Y-axis guide unit, and the third driver is disposed on the first X-axis guide unit or the first Y-axis guide unit to drive the first X-axis guide unit to move along the first Y-axis guide unit;

[0024] The first Y-axis guide unit is disposed on the stage and is parallel to the side of the electrode to be tested.

[0025] In some embodiments, the X-axis guide unit and the Y-axis guide unit are both provided with distance measuring modules to detect the moving distance of the reference electrode probe along the X-axis and the Y-axis.

[0026] In some embodiments, the first driving unit includes a Z-axis guide unit and a first driver, and the second driving unit includes a second X-axis guide unit, a second Y-axis guide unit, a fourth driver, and a fifth driver;

[0027] The Z-axis guide unit is arranged above the stage, the reference electrode probe and the first driver are arranged on the Z-axis guide unit, and the first driver is connected to the reference electrode probe to drive the reference electrode probe to reciprocate in a direction perpendicular to the electrode piece to be tested;

[0028] The second X-axis guide unit is connected to the second Y-axis guide unit and is arranged at the lower side of the worktable. The fourth driver is connected to the first X-axis guide unit to drive the worktable to move along the X-axis. The fifth driver is connected to the second Y-axis guide unit to drive the worktable to move along the Y-axis.

[0029] In some embodiments, the device further comprises a vacuum pump connected to the stage to evacuate the area of ​​the stage where the electrode to be tested is placed.

[0030] According to another aspect of the present invention, a method for measuring the electrode potential of a pole piece is provided. Based on the electrode potential measuring device of a pole piece according to any of the above embodiments, the method comprises:

[0031] Step 1, the electrode piece to be tested is placed on the stage, the electrode tab of the electrode piece to be tested is electrically connected to the positive electrode of the workstation, and the reference electrode probe is electrically connected to the negative electrode of the workstation;

[0032] Step 2: Control the second driving unit to drive the reference electrode probe to move in a plane parallel to the electrode piece to be tested, and control the first driving unit to drive the reference electrode probe to contact the surface of the electrode piece to be tested, so as to form a path to measure the electrode potential of the electrode piece to be tested in the contact area of ​​the reference electrode probe;

[0033] Step three, repeating step two to detect the electrode potentials of multiple areas of the electrode piece to be tested, and generating an electrode potential map of the electrode piece to be tested.

[0034] Compared with the prior art, the present invention has obvious advantages and beneficial effects. By means of the above technical solution, the electrode potential measuring device and electrode potential measuring method of the present invention can achieve considerable technical progress and practicality, and have wide industrial utilization value, and have at least the following advantages:

[0035] The present invention sets the first driving part and the second driving part so that the reference electrode probe can achieve full coverage of the electrode to be tested by changing its position, measure the electrode potential at multiple positions in the electrode to be tested, generate an electrode potential map of the electrode to be tested, and then determine the lithium concentration distribution of the electrode to be tested according to the electrode potential map of the electrode to be tested. The problem of human error in judging by the color change of the electrode is solved. Compared with the expensive equipment used in quantitative analysis methods (neutron diffraction, X-ray diffraction, Raman spectroscopy, etc.), the device of the present invention has low cost and can realize rapid detection of complete electrode pieces. Compared with the electron microscope micro-nano area observation method, it can realize large-viewing field detection on a macro scale (any position of the entire electrode piece), and the detection efficiency is higher and faster.

[0036] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of an electrode potential measuring device of a pole piece according to an embodiment of the present invention;

[0038] Figure 2 It is a schematic structural diagram of a reference electrode probe in a first state according to an embodiment of the present invention;

[0039] Figure 3It is a schematic structural diagram of a reference electrode probe in a second state according to an embodiment of the present invention;

[0040] Figure 4 Schematic diagram of an electrode potential diagram of a pole piece to be tested according to an embodiment of the present invention.

[0041]

Explanation of symbols

[0042] 1: Stage

[0043] 2: Reference electrode probe

[0044] 21: Probe housing

[0045] 211: First Shell

[0046] 212: Second shell

[0047] 22: Reference electrode

[0048] 23: Diaphragm

[0049] 24: Opening

[0050] 25: Elastic parts

[0051] 26: Liquid injection hole

[0052] 3: First drive unit

[0053] 31: Z-axis guide unit

[0054] 4: Second drive unit

[0055] 41: First X-axis guide unit

[0056] 42: First Y-axis guide unit

[0057] 5: Pole piece to be tested

[0058] 6: Electrode potential diagram DETAILED DESCRIPTION

[0059] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods and effects of an electrode potential measuring device and an electrode potential measuring method of an electrode proposed by the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0060] Experimental studies have shown that the lithium concentration distribution of the electrode sheet and the electrode potential (V vs.Li) have a close corresponding relationship. For example, the electrode potential of the graphite negative electrode sheet decreases with the increase of the concentration and depth of lithium insertion. Based on this, the present invention characterizes the lithium concentration distribution of a large range of electrode sheets by quantitatively measuring the electrode potential of the electrode sheet, and then judges the electrochemical reaction process of the electrode sheet, such as the state of charge, the degree of lithium precipitation, the abnormal failure area, the residual lithium concentration of the electrode sheet, the electrolyte infiltration condition, etc.

[0061] See also Figure 1 As shown, according to an embodiment of the present invention, a device for measuring electrode potential of a pole piece is provided, and the device includes: a stage 1, a reference electrode probe 2, a first driving part 3 and a second driving part 4.

[0062] The stage 1 is used to carry the electrode 5 to be tested. The stage 1 is made of marble or metal.

[0063] In one embodiment, in order to ensure that the position of the electrode piece 5 to be measured will not be offset during the measurement process, resulting in inaccurate measurement of the electrode potential of the electrode piece 5 to be measured, the electrode potential measuring device of the electrode piece further includes a vacuum pump (not shown in the figure), which is connected to the stage 1, more specifically, the vacuum pump is connected to the area of ​​the stage 1 where the electrode piece 5 to be measured is placed, so as to extract the gas in the area where the electrode piece 5 to be measured is placed, so as to make it in a vacuum state, and then firmly adsorb the electrode piece 5 to be measured on the stage 1.

[0064] It should be noted that the vacuum state in this embodiment does not mean that the area is in a complete vacuum state, but that part of the air in the area is extracted to be able to adsorb the electrode 5 to be tested.

[0065] The reference electrode probe 2 is used to contact the electrode piece 5 to be tested, so as to measure the electrode potential of the area in the electrode piece 5 to be tested where the reference electrode probe 2 contacts.

[0066] In one embodiment, if Figure 2 and Figure 3 As shown, the reference electrode probe 2 includes: a probe housing 21 , a reference electrode 22 and a diaphragm 23 .

[0067] The reference electrode 22 is disposed in the probe housing 21, and electrolyte is stored in the probe housing 21. An opening 24 is disposed at one end of the probe housing 21, and the diaphragm 23 is connected to the probe housing 21 and covers the opening 24. Specifically, the opening 24 is disposed at one end of the probe housing 21 facing the electrode piece 5 to be tested.

[0068] In the process of measuring the electrode potential of the electrode piece 5 to be tested, the electrode ear of the electrode piece 5 to be tested is connected to the positive electrode of the electrochemical workstation through a connecting line, and the reference electrode probe 2 is connected to the negative electrode of the electrochemical workstation through a connecting line. When the reference electrode probe 2 contacts the surface of the electrode piece 5 to be tested, the reference electrode 22 contacts one side of the diaphragm 23, and the other side of the diaphragm 23 contacts the surface of the electrode piece 5 to be tested. At this time, the reference electrode 22 squeezes the electrolyte in the diaphragm 23 to the contact area between the electrode piece 5 to be tested and the diaphragm 23, so that the electrolyte infiltrates the contact area. At this time, the reference electrode 22, the diaphragm 23 and the contact area form a passage similar to a button battery, and the electrochemical workstation measures the open circuit voltage of the contact area in the electrode piece 5 to be tested.

[0069] The probe housing 21 is made of PTFE (Poly tetra fluoroethylene) or PEEK (poly (ether-ether-ketone)). The reference electrode 22 is a stainless steel gold-plated cylinder, and a lithium layer is electroplated or a lithium sheet is set at one end of the stainless steel gold-plated cylinder facing the diaphragm 23, or the reference electrode 22 is directly made of a metal lithium rod. The diaphragm 23 can be a single-layer film or a multi-layer film, and the material of the diaphragm 23 can be a single-layer film of PE (polyethylene) or PP (polypropylene), or a multi-layer film of PP / PE / PP composite, or a composite film composed of PE and PP and ceramic or boehmite.

[0070] Furthermore, if Figure 2 and Figure 3 As shown, the probe housing 21 includes a first shell 211 and a second shell 212. The reference electrode 22 is inserted into the first shell 211, and the second shell 212 is slidably mounted on one end of the first shell 211 facing the electrode piece 5 to be measured. An elastic member 25 is arranged in the first shell 211 and the second shell 212, and the two ends of the elastic member 25 are respectively pressed against the first shell 211 and the second shell 212. The opening 24 is arranged on one end of the second shell 212 away from the first shell 211.

[0071] The diaphragm 23 may be disposed inside the second housing 212 and cover the opening 24, or may be disposed outside the second housing 212 and cover the opening 24. Preferably, the diaphragm 23 is disposed outside the second housing 212 to facilitate replacement of the diaphragm 23.

[0072] like Figure 3 As shown, when an external force is applied to the first housing 211, the first housing 211 compresses the elastic member 25, and the reference electrode 22 moves toward the diaphragm 23 and contacts the diaphragm 23. Figure 2As shown, when the external force is removed, under the action of the elastic member 25 , the reference electrode 22 moves away from the diaphragm 23 .

[0073] In one embodiment, a liquid injection hole 26 is provided on the first housing 211 to facilitate the filling of electrolyte. The liquid injection hole 26 can be provided on the side wall of the first housing 211 or on the top of the first housing 211, but the present invention is not limited thereto.

[0074] like Figure 1 As shown, the first driving part 3 is connected to the reference electrode probe 2, and is used to drive the reference electrode probe 2 to reciprocate in a direction perpendicular to the electrode piece 5 to be tested. The second driving part 4 is used to drive the first driving part 3 or the stage 1 to move, so that the reference electrode probe 2 can cover at least part of the electrode piece 5 to be tested.

[0075] Specifically, the second driving unit 4 can drive the first driving unit 3 to move, that is, drive the reference electrode probe 2 connected to the first driving unit 3 to move, or the second driving unit 4 drives the stage 1 to move, that is, drives the electrode piece 5 to be tested placed on the stage 1 to move, so that the reference electrode probe 2 can contact part or all of the surface of the electrode piece 5 to be tested.

[0076] In one embodiment, if Figure 1 As shown, the first driving part 3 includes a Z-axis guide unit 31 and a first driver (not shown in the figure), and the second driving part 4 includes a first X-axis guide unit 41, a first Y-axis guide unit 42, a second driver (not shown in the figure) and a third driver (not shown in the figure). The reference electrode probe 2 and the first driver are arranged on the Z-axis guide unit 31, and the first driver is connected to the reference electrode probe 2 to drive the reference electrode probe 2 to reciprocate in a direction perpendicular to the electrode piece 5 to be measured. The Z-axis guide unit 31 is connected to the first X-axis guide unit 41, and the second driver is arranged on the Z-axis guide unit 31 or the first X-axis guide unit 41 to drive the Z-axis guide unit 31 to move along the first X-axis guide unit 41. The first X-axis guide unit 41 is connected to the first Y-axis guide unit 42, and the third driver is arranged on the first X-axis guide unit 41 or the first Y-axis guide unit 42 to drive the first X-axis guide unit 41 to move along the first Y-axis guide unit 42. The first Y-axis guide unit 42 is arranged on the stage 1 and is parallel to the side of the electrode piece 5 to be measured.

[0077] Specifically, the first Y-axis guide unit 42 is arranged on the stage 1 and is parallel to the long side of the electrode piece 5 to be tested. The first Y-axis guide unit 42 can be one and is arranged on one side of the electrode piece 5 to be tested, or two and are arranged on two opposite sides of the electrode piece 5 to be tested. The first X-axis guide unit 41 is connected to the first Y-axis guide unit 42 and is parallel to the short side of the electrode piece 5 to be tested, that is, the first X-axis guide unit 41 and the first Y-axis guide unit 42 intersect vertically. The third driver can be arranged on the first X-axis guide unit 41 or on the first Y-axis guide unit 42. The third driver is used to drive the first X-axis guide unit 41 to move along the first Y-axis guide unit 42, that is, drive the reference electrode probe 2 to move along the Y-axis, and the Y-axis is parallel to the long side of the electrode piece 5 to be tested.

[0078] The Z-axis guide unit 31 is connected to the first X-axis guide unit 41, and the Z-axis guide unit 31 is arranged perpendicularly to the electrode piece 5 to be tested, that is, the Z-axis guide unit 31 is perpendicularly connected to the first X-axis guide unit 41. The second driver is arranged on the Z-axis guide unit 31 or the first X-axis guide unit 41. The second driver is used to drive the Z-axis guide unit 31 to move along the first X-axis guide unit, that is, to drive the reference electrode probe 2 to move along the X-axis, and the X-axis is parallel to the short side of the electrode piece 5 to be tested.

[0079] The reference electrode probe 2 and the first driver are arranged on the Z-axis guide unit 31 , and the first driver is used to drive the reference electrode probe 2 to move along the Z-axis guide unit 31 , that is, to drive the reference electrode probe 2 to move along the Z-axis, which is perpendicular to the electrode piece 5 to be tested.

[0080] In this embodiment, the reference electrode probe 2 is driven to move to any position of the electrode piece 5 to be tested by linkage of three axes (i.e., X-axis, Y-axis, and Z-axis), thereby realizing large-area electrode potential detection of the electrode piece 5 to be tested, and finally generating the following Figure 4 The electrode potential diagram 6 of the electrode piece 5 to be tested is shown.

[0081] Furthermore, distance measuring modules (not shown in the figure) are respectively provided on the first X-axis guide unit 41 and the first Y-axis guide unit 42 to detect the moving distance of the reference electrode probe 2 along the X-axis and the Y-axis, thereby realizing precise control of the movement of the reference electrode probe 2.

[0082] Preferably, the first driver is a servo motor, the second driver and the third driver are linear motors, and the distance measuring module is a grating ruler.

[0083] In another embodiment, the first driving part 3 includes a Z-axis guide unit 31 and a first driver, and the second driving part 4 includes a second X-axis guide unit (not shown in the figure), a second Y-axis guide unit (not shown in the figure), a fourth driver (not shown in the figure) and a fifth driver (not shown in the figure). The Z-axis guide unit 31 is arranged above the stage 1, the reference electrode probe 2 and the first driver are arranged on the Z-axis guide unit 31, and the first driver is connected to the reference electrode probe 2 to drive the reference electrode probe 2 to reciprocate in a direction perpendicular to the electrode piece 5 to be tested. The second X-axis guide unit is connected to the second Y-axis guide unit and is connected to the lower side of the stage 1, the fourth driver is connected to the second X-axis guide unit to drive the stage 1 to move along the X-axis, and the fifth driver is connected to the second Y-axis guide unit to drive the stage 1 to move along the Y-axis.

[0084] Specifically, the Z-axis guiding unit is arranged above the stage 1, and the reference electrode probe 2 and the first driver are arranged on the Z-axis guiding unit 31. The first driver is used to drive the reference electrode probe 2 to move along the Z-axis guiding unit 31, that is, to drive the reference electrode probe 2 to move along the Z-axis, which is perpendicular to the electrode piece 5 to be tested.

[0085] The second X-axis guide unit is connected to the second Y-axis guide unit and is arranged on the lower side of the stage 1. Preferably, the second X-axis guide unit and the second Y-axis guide unit intersect vertically. The fourth driver is connected to the second X-axis guide unit to drive the stage 1 to move along the X-axis, that is, to drive the pole piece 5 to be tested to move along the X-axis. The X-axis is parallel to the short side of the pole piece 5 to be tested. The fifth driver is connected to the second Y-axis guide unit to drive the stage 1 to move along the Y-axis, that is, to drive the pole piece 5 to be tested to move along the Y-axis. The Y-axis is parallel to the long side of the pole piece 5 to be tested.

[0086] In this embodiment, the reference electrode probe 2 is fixed in a plane parallel to the electrode piece 5 to be measured, and only moves perpendicular to the electrode piece 5 to be measured. The movement of the electrode piece 5 to be measured is achieved by controlling the movement of the stage 1, so that the reference electrode probe 2 can cover any position of the electrode piece 5 to be measured.

[0087] In this embodiment, a distance measurement module may be provided on both the second X-axis guide unit and the second Y-axis guide unit to achieve precise control over the movement of the stage 1 .

[0088] Preferably, the first driver is a servo motor, the fourth driver and the fifth driver are linear motors, and the distance measuring module is a grating ruler.

[0089] According to an embodiment of the present invention, a method for measuring the electrode potential of a pole piece is further provided. Based on the electrode potential measuring device of a pole piece in any of the above embodiments, the method comprises:

[0090] Step 1: The electrode to be tested is placed on the stage, the electrode ear of the electrode to be tested is electrically connected to the positive electrode of the workstation, and the reference electrode probe is electrically connected to the negative electrode of the workstation.

[0091] Specifically, after placing the electrode to be tested on the stage, the air in the area where the electrode to be tested is placed can be extracted by a vacuum pump so that the electrode to be tested is adsorbed on the stage, ensuring that the electrode to be tested will not be shifted during the measurement process.

[0092] The pole ear of the electrode to be tested is connected to the positive electrode of the electrochemical workstation through a connecting line, and the reference electrode probe is connected to the negative electrode of the electrochemical workstation through a connecting line.

[0093] The electrochemical workstation can use Autolab, which has a measurement point accuracy of 0.2%, a resolution of 300nV, and a measurement voltage range of 0 to 4.3V.

[0094] Step 2: Control the second driving unit to drive the reference electrode probe to move in a plane parallel to the electrode piece to be tested, and control the first driving unit to drive the reference electrode probe to contact the surface of the electrode piece to be tested, so as to form a path to measure the electrode potential of the reference electrode probe contact area in the electrode piece to be tested.

[0095] Specifically, the second driving unit is controlled to drive the reference electrode probe to move in a plane parallel to the electrode piece to be tested. When the reference electrode probe reaches the test position, the first driving unit is controlled to drive the reference electrode probe to move downward in a direction perpendicular to the electrode piece to be tested, so that the reference electrode probe contacts the test position.

[0096] During the measurement process, the area of ​​the electrode piece to be measured in a single measurement is determined by the diameter of the reference electrode probe. The intervals between multiple test positions are pre-set and controlled by the second drive unit. The stamping pressure, holding time, etc. of the electrode piece to be measured in a single measurement are controlled by the first drive unit.

[0097] In a specific embodiment, when the first driving unit drives the reference electrode probe to contact the electrode piece to be tested, the reference electrode on the reference electrode probe squeezes the electrolyte in the diaphragm to wet the area of ​​the electrode piece to be tested that the reference electrode probe contacts, forming a passage similar to a button battery, and the electrochemical workstation measures the electrode voltage of the reference electrode probe contact area in the electrode piece to be tested.

[0098] Step three, repeating step two to detect the electrode potentials of multiple areas of the electrode piece to be tested, and generating an electrode potential map of the electrode piece to be tested.

[0099] Specifically, the reference electrode probe is driven to move by repeatedly controlling the first driving unit and the second driving unit, so that the reference electrode probe measures the electrode potentials at multiple positions in the electrode piece to be tested, and finally generates an electrode potential map of the electrode piece to be tested according to multiple measurements. The distribution of lithium concentrations in different areas of the electrode piece to be tested can be understood through the electrode potential map.

[0100] The present invention uses the electrode potential measuring device of the electrode piece to realize the XYZ three-axis movement of the reference electrode probe, and then uses the reference electrode probe to map the electrode potential diagram of the electrode piece to be tested, quantitatively characterizes the lithium concentration distribution of the activated electrode piece, and helps to quickly determine the electrochemical reaction information of different areas of the electrode piece (such as the lithium insertion situation). The present invention closely associates the measured electrode potential size and distribution with the electrode piece state, avoiding the artificial error of the electrode color change judgment method and the shortcomings of neutron diffraction and other methods that require expensive testing instruments and can only measure a small range.

[0101] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A device for measuring electrode potential of an electrode piece, characterized in that: include: A stage, a reference electrode probe, a first driving unit and a second driving unit; Wherein, the stage is used to carry the pole piece to be tested; The reference electrode probe is used to contact the electrode piece to be tested, so as to measure the electrode potential of the area in the electrode piece to be tested where the reference electrode probe contacts; The reference electrode probe comprises a probe housing, a reference electrode and a diaphragm; Wherein, electrolyte is stored in the probe housing, and the probe housing includes a first shell and a second shell; Wherein, the reference electrode is inserted into the first shell, and the second shell is slidably mounted on one end of the first shell; An elastic member is disposed in the first shell and the second shell, and two ends of the elastic member abut against the first shell and the second shell respectively; An opening is provided at one end of the second shell, and the diaphragm is provided on the outer side of the one end of the second shell, and the diaphragm covers the opening. When the first driving unit drives the reference electrode probe to contact the electrode piece to be measured, the reference electrode contacts one side of the diaphragm, and the other side of the diaphragm contacts the electrode piece to be measured; The opening is provided on one end of the second shell away from the first shell, and under the driving of the first driving unit, the first shell compresses the elastic member, and one end of the reference electrode contacts the one side of the diaphragm; The first driving unit is connected to the reference electrode probe, and drives the reference electrode probe to reciprocate in a direction perpendicular to the electrode piece to be tested. When the first driving unit drives the reference electrode probe to contact the electrode piece to be tested, the reference electrode squeezes the electrolyte in the diaphragm to the contact area between the electrode piece to be tested and the diaphragm, so that the electrolyte infiltrates the contact area. The second driving unit is used to drive the first driving unit or the stage to move so that the reference electrode probe covers at least a portion of the surface of the electrode piece to be tested.

2. The electrode potential measuring device of the electrode piece according to claim 1, characterized in that: The first shell is provided with a liquid injection hole.

3. The electrode potential measuring device of a pole piece according to claim 1 or 2, characterized in that: The first driving part includes a Z-axis guide unit and a first driver, and the second driving part includes a first X-axis guide unit, a first Y-axis guide unit, a second driver and a third driver; The reference electrode probe and the first driver are arranged on the Z-axis guide unit, and the first driver is connected to the reference electrode probe to drive the reference electrode probe to reciprocate in a direction perpendicular to the electrode piece to be tested; The Z-axis guide unit is connected to the first X-axis guide unit, and the second driver is disposed on the Z-axis guide unit or the first X-axis guide unit to drive the Z-axis guide unit to move along the first X-axis guide unit; The first X-axis guide unit is connected to the first Y-axis guide unit, and the third driver is disposed on the first X-axis guide unit or the first Y-axis guide unit to drive the first X-axis guide unit to move along the first Y-axis guide unit; The first Y-axis guide unit is disposed on the stage and is parallel to the side of the electrode to be tested.

4. The electrode potential measuring device of the electrode piece according to claim 3, characterized in that: The X-axis guide unit and the Y-axis guide unit are both provided with distance measuring modules to detect the moving distance of the reference electrode probe along the X-axis and the Y-axis.

5. The electrode potential measuring device of a pole piece according to claim 1 or 2, characterized in that: The first driving part includes a Z-axis guide unit and a first driver, and the second driving part includes a second X-axis guide unit, a second Y-axis guide unit, a fourth driver and a fifth driver; The Z-axis guide unit is arranged above the stage, the reference electrode probe and the first driver are arranged on the Z-axis guide unit, and the first driver is connected to the reference electrode probe to drive the reference electrode probe to reciprocate in a direction perpendicular to the electrode piece to be tested; The second X-axis guide unit is connected to the second Y-axis guide unit and is arranged at the lower side of the worktable. The fourth driver is connected to the second X-axis guide unit to drive the worktable to move along the X-axis. The fifth driver is connected to the second Y-axis guide unit to drive the worktable to move along the Y-axis.

6. The electrode potential measuring device of a pole piece according to claim 1, characterized in that: The device also includes a vacuum pump connected to the stage to evacuate the area of ​​the stage where the electrode to be tested is placed.

7. A method for measuring the electrode potential of an electrode piece, characterized in that: The electrode potential measuring device of the electrode piece according to any one of claims 1 to 5, the method comprising: Step 1, the electrode piece to be tested is placed on the stage, the electrode tab of the electrode piece to be tested is electrically connected to the positive electrode of the workstation, and the reference electrode probe is electrically connected to the negative electrode of the workstation; Step 2: Control the second driving unit to drive the reference electrode probe to move in a plane parallel to the electrode piece to be tested, and control the first driving unit to drive the reference electrode probe to contact the surface of the electrode piece to be tested, so as to form a path to measure the electrode potential of the electrode piece to be tested in the contact area of ​​the reference electrode probe; Step three, repeating step two to detect the electrode potentials of multiple areas of the electrode piece to be tested, and generating an electrode potential map of the electrode piece to be tested.

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