In-situ force electrochemical performance testing device and method for lithium battery

Abstract

The application provides a lithium battery in-situ force electrochemical performance testing device and method, and belongs to the technical field of battery performance testing, and comprises: an electrochemical cell, electrolyte is injected into the cavity of the electrochemical cell; a reference electrode is arranged on one side of the inner wall of the cavity of the electrochemical cell; a counter electrode is arranged on the other side of the inner wall of the cavity of the electrochemical cell; an electrode clamp is arranged on the bottom wall of the cavity of the electrochemical cell, and a working electrode is clamped on the electrode clamp; an external electrode is arranged on the outer wall of the electrochemical cell and is used for connecting an external electrochemical analysis device; the reference electrode, the counter electrode and the working electrode are connected with the external electrode through wires. The application can realize in-situ force electrochemical performance testing of a lithium battery electrode, obtain dynamic mechanical response characteristics of the electrode in an electrochemical reaction process, and study real-time change rules of the lithium battery electrode under different working conditions.

Description

Technical Field

[0001] This invention belongs to the field of battery performance testing technology, specifically relating to an in-situ electrochemical performance testing device and method for lithium batteries, and more specifically to a testing device and method for simultaneously performing electrochemical testing and in-situ nanoindentation testing on lithium battery electrodes. Background Technology

[0002] Lithium-ion batteries possess significant advantages such as high energy density, good rate performance, long cycle life, and strong environmental adaptability, leading to their widespread and in-depth application in numerous fields, including electronic products, power tools, and new energy vehicles. As an integrated energy storage and conversion device, lithium-ion batteries involve the coupled influence of multiple factors, including mechanical structure, electrochemical reactions, and temperature. During the charging and discharging process, the repeated insertion and extraction of lithium ions causes repeated expansion and contraction of the active material, resulting in structural deformation and compression / stretching of adjacent components. This, in turn, alters the mechanical properties of the electrode during the electrochemical reaction. Electrode deformation and cracking often lead to electrochemical reaction failure, causing lithium-ion battery malfunctions. Therefore, characterizing the mechanical properties of lithium-ion batteries under different electrochemical conditions will help further analyze the failure mechanism of lithium-ion batteries and develop more durable and efficient lithium-ion batteries.

[0003] The electrochemical reactions in lithium-ion batteries involve phenomena such as SEI film formation and active material denaturation, making them particularly sensitive to environmental factors like moisture and oxygen concentration. Therefore, in-situ testing devices for lithium-ion batteries are mostly sealed systems. However, current material mechanical property testing methods are mostly open systems, requiring the tested materials to have a certain degree of environmental adaptability. Consequently, most current lithium-ion battery mechanical property testing methods are non-in-situ characterizations, involving disassembly and reprocessing of the lithium-ion battery after a certain degree of electrochemical reaction, followed by mechanical property testing of the active materials and other substances. This process inevitably leads to some distortion in the obtained data. Summary of the Invention

[0004] To overcome the shortcomings of the existing technology, this invention provides an in-situ mechanochemical performance testing device and method for lithium batteries. This device and method can simultaneously perform in-situ mechanical performance testing on lithium battery electrodes under different electrochemical reaction conditions, thereby obtaining the mechanochemical coupling characteristics of the lithium battery.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A lithium battery in-situ mechanochemical performance testing device includes:

[0007] An electrochemical cell, wherein the cavity of the electrochemical cell is filled with an electrolyte;

[0008] A reference electrode is disposed on one side of the inner wall of the cavity of the electrochemical cell;

[0009] The counter electrode is disposed on the other side of the inner wall of the cavity of the electrochemical cell;

[0010] An electrode clamp is disposed on the bottom wall of the cavity of the electrochemical cell, and a working electrode is held thereon.

[0011] An external electrode is disposed on the outer wall of the electrochemical cell for connecting to an external electrochemical analysis device;

[0012] The reference electrode, counter electrode, and working electrode are all connected to the external electrode via wires.

[0013] During testing, the testing device is placed under the indenter of the nanoindentation tester.

[0014] Preferably, the electrode clamp includes a conductive connector disposed on the bottom wall of the cavity of the electrochemical cell and a fixing member disposed on the conductive connector. The working electrode is disposed on the conductive connector and located inside the fixing member. The working electrode is connected to the external electrode through the conductive connector.

[0015] Preferably, the fixing member includes clamps disposed around the conductive connector, and the clamps are connected to the conductive connector by a return spring.

[0016] Preferably, the fastener is made of an insulating material.

[0017] Preferably, the wire is embedded in the body of the electrochemical cell.

[0018] Preferably, the material of the electrochemical cell is polytetrafluoroethylene.

[0019] Preferably, the electrolyte is lithium hexafluorophosphate.

[0020] Based on the same inventive concept, another objective of this invention is to provide a method for in-situ mechanochemical performance testing of lithium batteries, comprising the following steps:

[0021] The working electrode is loaded onto the conductive connector and clamped by the fixing member;

[0022] The electrochemical cell was fixed on the stage of the nanoindentation tester.

[0023] Connect the external electrode to an external electrochemical analysis device;

[0024] An electrolyte is injected into the cavity of the electrochemical cell, and the working electrode, reference electrode, and counter electrode are all immersed in the electrolyte.

[0025] The test area of ​​the working electrode is marked using the optical mirror built into the nanoindentation tester;

[0026] Based on the Oliver-Pharr method, the indenter of a nanoindentation tester is used to press down on the target area marked on the working electrode and generate scratches.

[0027] The indenter of the nanoindentation tester sends the data collected during the pressing process to the host of the nanoindentation tester for analysis, in order to obtain the mechanical properties of the working electrode during the electrochemical reaction.

[0028] The reference electrode and counter electrode transmit the collected data to an external electrochemical analysis device, which analyzes the data to obtain the electrochemical performance of the working electrode during the electrochemical reaction.

[0029] Preferably, during testing, the indenter of the nanoindentation tester sends the collected data to the host of the nanoindentation tester for analysis, obtaining the indentation geometric parameters and load-displacement curve of the working electrode during the electrochemical reaction, and obtaining the mechanical properties of the working electrode through the indentation geometric parameters and load-displacement curve.

[0030] Preferably, during testing, the electrochemical cell and the associated nanoindentation tester are placed in a glove box filled with argon gas, where the water-oxygen concentration is below 0.1 mg / L. -1 .

[0031] The in-situ electrochemical performance testing device and method for lithium batteries provided by this invention have the following beneficial effects:

[0032] Unlike non-in-situ testing, this invention can simultaneously perform in-situ chemical performance testing of the working electrode using a reference electrode and a counter electrode. At the same time, it can perform in-situ mechanochemical performance testing of the working electrode using a nanoindentation tester, thereby obtaining the dynamic mechanical response characteristics of the working electrode during the electrochemical reaction process and studying the real-time change law of the working electrode under different operating conditions. In addition, this device can be combined with more characterization methods for joint and synchronous testing. Attached Figure Description

[0033] To more clearly illustrate the embodiments and design schemes of the present invention, the accompanying drawings required for this embodiment will be briefly described below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a front view of the in-situ mechanochemical performance testing device for lithium batteries according to Embodiment 1 of the present invention;

[0035] Figure 2 This is a top view of the in-situ mechanochemical performance testing device for lithium batteries according to Embodiment 1 of the present invention;

[0036] Figure 3 A flowchart of the in-situ mechanochemical performance testing method for lithium batteries provided by the present invention;

[0037] Explanation of reference numerals in the attached diagram: 1-Electrochemical cell, 2-Reference electrode, 3-Counter electrode, 4-Fixing component, 5-Conductive connector, 6-Wire, 7-External electrode, 8-Working electrode, 9-Pressure head, 10-Electrolyte. Detailed Implementation

[0038] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0039] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "connected" or "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, which will not be elaborated further here.

[0041] Example 1

[0042] This invention provides an in-situ mechanochemical performance testing device and method for lithium batteries, specifically as follows: Figure 1 and Figure 2 As shown, it includes an electrochemical cell 1, a reference electrode 2, a counter electrode 3, an external electrode 7, and an electrode clamp.

[0043] Specifically, the cavity of the electrochemical cell 1 is filled with electrolyte 10. In this embodiment, electrolyte 10 is lithium hexafluorophosphate. The reference electrode 2 is disposed on one side of the inner wall of the cavity of the electrochemical cell 1; the counter electrode 3 is disposed on the other side of the inner wall of the cavity of the electrochemical cell 1; the electrode clamp is disposed on the bottom wall of the cavity of the electrochemical cell 1, and the working electrode 8 is held thereon; the external electrode 7 is disposed on the outer wall of the electrochemical cell 1 for connecting to an external electrochemical analysis device.

[0044] The reference electrode 2 voltage, the counter electrode 3 control current, and the working electrode 8 are all connected to the external electrode 7 through wires 6 embedded in the body of the electrochemical cell 1.

[0045] During testing, the testing device is placed below the indenter 9 of the nanoindentation tester.

[0046] Furthermore, in this embodiment, the electrode clamp includes a conductive connector 5 disposed on the bottom wall of the cavity of the electrochemical cell 1 and a fixing member 4 disposed on the conductive connector 5. The working electrode 8 is disposed on the conductive connector 5 and located inside the fixing member 4. The working electrode 8 is connected to the external electrode 7 through the conductive connector 5.

[0047] Specifically, in this embodiment, the fixing member 4 includes clamps disposed around the conductive connector 5. The clamps are connected to the conductive connector 5 by a return spring. The fixing member 4 in this embodiment is similar to the clamp structure in the prior art.

[0048] Furthermore, in this embodiment, the fixing member 4 is made of an insulating material to prevent it from coming into contact with the device. The electrochemical cell 1 is made of polytetrafluoroethylene to avoid reaction with the electrolyte.

[0049] Based on the same inventive concept, this embodiment also provides a method for in-situ electrochemical performance testing of lithium batteries. In this embodiment, the working electrode 8 is a lithium cobalt oxide thin film electrode. Before testing, a lithium cobalt oxide (LiCoO2) thin film is first deposited by magnetron sputtering on an aluminum foil current collector to obtain multiple lithium cobalt oxide thin film electrodes of the same batch.

[0050] like Figure 3 As shown, the testing process includes the following steps:

[0051] Step 1: Load the lithium cobalt oxide thin film electrode onto the conductive connector 5, and clamp the lithium cobalt oxide thin film electrode with the fixing member 4 to maintain a tight and stable contact between the aluminum foil current collector side of the lithium cobalt oxide thin film electrode and the conductive connector 5.

[0052] Step 2: Fix the electrochemical cell 1 onto the stage of the nanoindentation tester.

[0053] Step 3: Connect the external electrode 7 to an external electrochemical analysis device; set the potential range to 2.0–3.7V, and perform cyclic charging and discharging at 1C, 2C, and 5C rates until the battery capacity decays to 80% SOC.

[0054] Step 4: Inject electrolyte 10 (1M lithium hexafluorophosphate organic solvent) into the cavity of electrochemical cell 1. The lithium cobalt oxide thin film electrode, reference electrode 2 and counter electrode 3 are all in electrolyte 10.

[0055] Step 5: Mark the test area of ​​the lithium cobalt oxide thin film electrode using the optical mirror built into the nanoindentation tester, ensuring that the spacing between each marked area is appropriate and that there is no mutual interference.

[0056] Step 6: Based on the Oliver-Pharr method, use the indenter 9 of the nanoindentation tester to press down on the marked target area on the lithium cobalt oxide thin film electrode and generate scratches.

[0057] Step 7: The Berkovich indenter 9 of the nanoindentation tester sends the data collected during the indentation process to the main unit of the nanoindentation tester for analysis to obtain the mechanical properties of the lithium cobalt oxide thin film electrode during the electrochemical reaction. Specifically, this is achieved by obtaining the indentation geometry parameters and load-displacement curves of the lithium cobalt oxide thin film electrode during the electrochemical reaction, and then using these parameters to determine the mechanical properties of the lithium cobalt oxide thin film electrode.

[0058] The reference electrode 2 and the counter electrode 3 send the collected data to an external electrochemical analysis device. The external electrochemical analysis device analyzes the data to obtain the electrochemical performance of the lithium cobalt oxide thin film electrode during the electrochemical reaction, and then obtains the dynamic mechanical response law of the lithium cobalt oxide thin film electrode with the electrochemical reaction.

[0059] By statistically analyzing data from multiple samples in the same batch, the mechano-electrochemical coupling law of lithium cobalt oxide thin film electrodes in the designed electrochemical reaction process was obtained.

[0060] Furthermore, in this embodiment, during testing, the electrochemical cell 1 and the accompanying nanoindentation tester were placed in a glove box filled with argon gas, where the water-oxygen concentration was below 0.1 mg / L. -1 .

[0061] In summary, the present invention has the following advantages:

[0062] 1. Unlike the distortion characteristics of non-in-situ testing, this invention can simultaneously achieve in-situ chemical performance testing of the working electrode through a reference electrode and a counter electrode. At the same time, it can achieve in-situ mechanochemical performance testing of the working electrode through a nanoindentation tester, thereby obtaining the dynamic mechanical response characteristics of the working electrode in the electrochemical reaction process and studying the real-time change law of the working electrode under different operating conditions.

[0063] 2. This invention can be used to study various types of lithium battery electrodes, including separators, polished composite electrodes, and metal foils, and is also applicable to similar materials for other batteries.

[0064] 3. The present invention has a simple and flexible composition, and the components are easy to replace and maintain. By adjusting the equipment configuration, it can be combined with more characterization methods for joint and synchronous testing.

[0065] The above-described embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited thereto. Any simple changes or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. A device for in-situ mechanochemical performance testing of lithium batteries, characterized in that, include: An electrochemical cell (1) is filled with an electrolyte (10) in its cavity. The material of the electrochemical cell (1) is polytetrafluoroethylene, and the electrolyte (10) is lithium hexafluorophosphate. A reference electrode (2) is disposed on one side of the inner wall of the cavity of the electrochemical cell (1); The counter electrode (3) is disposed on the other side of the inner wall of the cavity of the electrochemical cell (1); An electrode clamp is disposed on the bottom wall of the cavity of the electrochemical cell (1), and a working electrode (8) is clamped thereon. An external electrode (7) is disposed on the outer wall of the electrochemical cell (1) for connecting to an external electrochemical analysis device; The reference electrode (2), counter electrode (3) and working electrode (8) are all connected to the external electrode (7) via wires (6); During testing, the testing device is placed below the indenter (9) of the nanoindentation tester; The electrode clamp includes a conductive connector (5) disposed on the bottom wall of the cavity of the electrochemical cell (1) and a fixing member (4) disposed on the conductive connector (5). The working electrode (8) is disposed on the conductive connector (5) and located inside the fixing member (4). The working electrode (8) is connected to the external electrode (7) through the conductive connector (5).

2. The in-situ mechanochemical performance testing device for lithium batteries according to claim 1, characterized in that, The fixing member (4) includes clamps disposed around the conductive connector (5), and the clamps are connected to the conductive connector (5) by a return spring.

3. The in-situ mechanochemical performance testing device for lithium batteries according to claim 2, characterized in that, The fastener (4) is made of insulating material.

4. The in-situ mechanochemical performance testing device for lithium batteries according to claim 1, characterized in that, The conductor (6) is embedded in the body of the electrochemical cell (1).

5. A testing method for the in-situ mechanochemical performance testing device for lithium batteries according to any one of claims 1 to 4, characterized in that, Includes the following steps: The working electrode (8) is loaded onto the conductive connector (5) and clamped by the fixing member (4); The electrochemical cell (1) was fixed on the stage of the nanoindentation tester. Connect the external electrode (7) to an external electrochemical analysis device; Electrolyte (10) is injected into the cavity of the electrochemical cell (1), and the working electrode (8), reference electrode (2) and counter electrode (3) are all in the electrolyte (10); The test area of ​​the working electrode (8) is marked using the optical mirror built into the nanoindentation tester; Based on the Oliver-Pharr method, the indenter (9) of the nanoindentation tester is used to press down on the target area marked on the working electrode (8) and generate scratches; The indenter (9) of the nanoindentation tester sends the data collected during the pressing process to the host of the nanoindentation tester for analysis, and obtains the mechanical properties of the working electrode (8) during the electrochemical reaction process; The reference electrode (2) and the counter electrode (3) send the collected data to an external electrochemical analysis device. The external electrochemical analysis device analyzes the data to obtain the electrochemical performance of the working electrode (8) during the electrochemical reaction.

6. The in-situ mechanochemical performance testing method for lithium batteries according to claim 5, characterized in that, During testing, the indenter (9) of the nanoindentation tester sends the collected data to the host of the nanoindentation tester for analysis, and obtains the indentation geometric parameters and load-displacement curve of the working electrode (8) during the electrochemical reaction process. The mechanical properties of the working electrode (8) are obtained through the indentation geometric parameters and load-displacement curve.

7. The in-situ mechanochemical performance testing method for lithium batteries according to claim 6, characterized in that, During testing, the electrochemical cell (1) and the associated nanoindentation instrument were placed in a glove box filled with argon gas, where the water-oxygen concentration was below 0.1 mg / L. -1 .

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