In-situ SEM imaging and macroscopic battery testing system

Abstract

The invention discloses an in-situ SEM imaging and macroscopic battery testing system, and belongs to the technical field of solid-state battery testing, the in-situ SEM imaging and macroscopic battery testing system comprises an SEM-FIB double-beam electron microscope, the SEM-FIB double-beam electron microscope is fixedly connected with a vacuum transmission mechanism, the top of the vacuum transmission mechanism is fixedly connected with a solid-state battery clamp, the vacuum transmission mechanism is fixedly connected with the solid-state battery clamp, and the solid-state battery clamp is fixedly connected with the SEM-FIB double-beam electron microscope. A to-be-tested sample piece is arranged in the solid-state battery clamp, and the solid-state battery clamp is electrically connected with an electrochemical testing mechanism. The device can be used for observing the cross section of a macroscopic battery sample and observing the reaction in the battery during electrochemical testing, avoids a traditional nanometer manipulator electrifying mode, adopts a power supply for macroscopic battery testing to electrify, is similar to a macroscopic testing condition, and obtains an electrochemical curve similar to a macroscopic battery; and the reaction in the battery can be reflected more truly.

Description

Technical Field

[0001] The invention belongs to the technical field of solid-state battery testing, and in particular relates to an in-situ SEM imaging and macroscopic battery testing system. Background Art

[0002] In theory, solid-state batteries have perfect properties such as safety, high specific energy, and long cycle life. However, when solid-state batteries are actually used, many practical problems are found. First, lithium dendrites do not stop growing in solid electrolytes, and can even pass through hard ceramic solid electrolytes, causing solid-state batteries to short-circuit. Secondly, even if the ionic conductivity of solid electrolytes has reached the level of liquid electrolytes, the current solid-solid contact between the positive and negative electrodes and the electrolyte will still limit the efficiency of ion transmission, and even electrolyte decomposition will occur at the interface. In addition, solid-solid contact leads to more stringent requirements on the volume expansion of electrode materials. Slight volume changes can easily cause the rigid and brittle ceramic electrolyte sheets to crack during the cycle.

[0003] There are many problems with all-solid-state batteries, but the internal environment of solid electrolytes is more complex than that of liquid electrolytes, and there is a working environment with mechanical-chemical-electrical multi-field coupling. At the same time, it is difficult to sort out the cause of failure because the entire process of battery failure cannot be directly observed. Therefore, advanced in-situ imaging technology can further analyze the failure mechanism of all-solid-state batteries. Currently, the commonly used in-situ imaging technologies mainly include in-situ optical microscopy imaging technology, in-situ electron microscopy imaging technology, and in-situ CT imaging technology.

[0004] Optical microscopes are simple and practical, and they can observe microscopic changes in solid-state batteries. The Sakamoto team used an optical microscope and a dual-beam electron microscope together (Matter. 2020, 2, 1025-1048) to observe and focus ion beam cut the phenomena presented under the optical microscope under the electron microscope. They found that lithium dendrites grow in solid electrolytes accompanied by cracks, and the cracks provide channels for the deposition of lithium metal. However, the field of view under the optical microscope is large, and the failure area needs to be analyzed under the electron microscope, which limits the application of the optical microscope.

[0005] Electron microscopes can be divided into scanning electron microscopes and transmission electron microscopes. Huang et al. (Science. 2010, 330, 1515-1520) constructed an in-situ liquid battery in a transmission electron microscope and observed for the first time the morphological and structural changes of SnO2 nanowires during the lithium insertion process. Compared with the transmission electron microscope, although the scanning electron microscope has a lower resolution, it has excellent spatial imaging capabilities, its imaging is highly stereoscopic, and the electron beam damage is much less than that of the transmission electron microscope. The Zaghib group (Nano Letters. 2020, 20, 1607-1613) used in-situ SEM technology to observe the gas production of NMC during the solid-state battery cycle.

[0006] CT imaging technology is widely used to study the structural changes of electrode materials and solid electrolytes inside solid-state batteries. Due to the strong penetrability of X-rays, the working conditions of solid-state battery materials in X-ray transparent molds can be truly observed. The McDowell group (Nano Letters. 2017, 17, 2967-2972) used CT technology to observe the cracking process of LAGP electrode sheets during electrochemical cycling. Although CT technology is simple and easy to use and can perform in-situ non-destructive testing of batteries, its low resolution and high price limit its widespread application.

[0007] This shows that electron microscopy plays an important role in in-situ imaging. Its resolution is higher than that of optical microscopy and CT, and it has a variety of spectral characterization methods, and can also perform in-situ spectral characterization. Among electron microscopes, although the transmission electron microscope has the advantage of high resolution, its characterization scale is too small. It is usually used to observe samples at the nanoscale or a few microns. The observation area is too small, so it is often considered to be very different from macroscopic batteries and cannot present the reactions in real batteries. Scanning electron microscopes have high resolution and a large observation area, and can be used for microscopic in-situ characterization of macroscopic batteries. At present, in-situ SEM mostly uses nanomanipulators to bring battery materials into contact with metal negative electrodes, applies voltage through an external power supply, and observes the behavior of individual particles. This is similar to the in-situ battery in transmission electron microscopy. Since the solid / solid contact between the nanomanipulator / battery material / metal negative electrode is poor, the applied voltage is usually large, and the resulting electrochemical curve is also very different from the macroscopic battery curve. Some studies use macroscopic solid electrolyte sheets and improve the contact between the nanomanipulator and the surface of the electrolyte sheet by magnetron sputtering metal films. This method can measure a curve similar to the macroscopic electrochemical curve, but due to the sample structure, only the surface morphology changes of the electrolyte sheet can be observed, and the information inside the electrolyte cannot be observed. In addition, the nanomanipulator is mostly used to contact the electrolyte material when power is applied, which may cause problems with uneven battery distribution. Summary of the invention

[0008] The purpose of the present invention is to provide an in-situ SEM imaging and macroscopic battery testing system to solve the problems existing in the above-mentioned prior art.

[0009] To achieve the above-mentioned purpose, the present invention provides the following scheme: The present invention provides an in-situ SEM imaging and macro battery testing system, including a SEM-FIB dual-beam electron microscope, the SEM-FIB dual-beam electron microscope is fixedly connected to a vacuum transmission mechanism, the top of the vacuum transmission mechanism is fixedly connected to a solid-state battery fixture, the vacuum transmission mechanism is fixedly connected to the solid-state battery fixture, a sample to be tested is arranged in the solid-state battery fixture, and the solid-state battery fixture is electrically connected to an electrochemical testing mechanism.

[0010] Preferably, the vacuum transfer mechanism comprises a vacuum transfer sample stage, and the top surface of the vacuum transfer sample stage is provided with the SEM-FIB dual-beam electron microscope.

[0011] Preferably, a vacuum flange is provided on the SEM-FIB dual-beam electron microscope, and the electrodes on the solid-state battery fixture are connected to the wires on the vacuum flange.

[0012] Preferably, the vacuum flange is provided with an external wire connection port, the external wire connection port is connected to one end of an electrochemical test external wire, the other end of the electrochemical test external wire is electrically connected to the electrochemical testing mechanism, and the vacuum flange is provided with two electrode wire interfaces, the electrode wire interface is electrically connected to one end of an electrode external wire, and the other end of the electrode external wire is electrically connected to the solid-state battery fixture.

[0013] Preferably, the electrochemical testing mechanism is a LAND testing mechanism, and the LAND testing mechanism is electrically connected to the electrochemical testing external lead.

[0014] Preferably, the solid-state battery fixture includes a fixture base, a groove is provided in the fixture base, a screw is threadedly connected to one side of the groove, a slider is threadedly connected to the screw, the slider is slidably connected in the groove, and the sample to be tested is provided at one end of the slider away from the screw.

[0015] Preferably, the sample to be tested is an all-solid-state battery, and the all-solid-state battery is composed of a solid electrolyte and all-solid-state battery positive and negative electrode materials.

[0016] A method for using an in-situ SEM imaging and macroscopic battery testing system comprises the following steps:

[0017] A. Make test samples by using a powder tablet press;

[0018] B. Install the test sample and install the manufactured test sample into the solid-state battery fixture;

[0019] C. Place the solid-state battery fixture into the vacuum transfer mechanism;

[0020] D. Connect the solid-state battery fixture to the electrochemical testing mechanism;

[0021] E. Test the test samples.

[0022] The present invention discloses the following technical effects: the present invention can be used for cross-sectional observation of macroscopic battery samples and for observing the reactions inside the battery during electrochemical testing. At the same time, the present invention avoids the traditional nanomanipulator power-on method and adopts the power supply used for macroscopic battery testing, which is similar to the macroscopic testing conditions. The obtained electrochemical curve is also similar to that of the macroscopic battery, and can more realistically reflect the reactions inside the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0024] Figure 1 It is a structural schematic diagram of the in-situ SEM imaging and macroscopic battery testing system of the present invention;

[0025] Figure 2 The SEM image of the morphological structure evolution process of the lithium all-solid-state battery failure process in Example 1;

[0026] Figure 3 The voltage-time curve variation process measured by the LAND electrochemical testing system during the failure process of the lithium all-solid-state battery in Example 1;

[0027] Figure 4 This is a SEM image of the morphological structure evolution process of the NMC / LSPSCl / Li solid-state battery in the failure process in Example 2;

[0028] Figure 5 This is a SEM image of the morphological structure evolution process of the Li / LSPSCl / Li solid-state battery in Example 3 during the failure process.

[0029] In the figure: 1. SEM-FIB dual-beam electron microscope; 2. Vacuum transfer sample stage; 3. Vacuum flange; 4. External wire connection port; 5. Electrode wire interface; 6. Electrode external wire; 7. LAND test mechanism; 8. Fixture base; 9. Groove; 10. Screw; 11. Slider. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Reference Figure 1 As shown, this embodiment provides an in-situ SEM imaging and macro battery testing system, including a SEM-FIB dual-beam electron microscope 1, the SEM-FIB dual-beam electron microscope 1 is fixedly connected to a vacuum transmission mechanism, the top of the vacuum transmission mechanism is fixedly connected to a solid-state battery fixture, the vacuum transmission mechanism is fixedly connected to the solid-state battery fixture, a sample to be tested is arranged in the solid-state battery fixture, and the solid-state battery fixture is electrically connected to an electrochemical testing mechanism.

[0033] The sample to be tested is placed in the solid-state battery fixture. The sample to be tested is the assembly of the lithium battery. According to the battery system to be tested, different solid-state electrolytes, different negative electrodes, different positive electrodes and other solid-state battery components are designed, different interfaces such as negative electrode / solid electrolyte, positive electrode / solid electrolyte, and different solid-state batteries are tested using an electrochemical testing device, and the reaction process and the structural changes of the solid-state battery and its components are observed in situ through SEM imaging.

[0034] According to a further optimized solution, the vacuum transfer mechanism comprises a vacuum transfer sample stage 2 , and a SEM-FIB double-beam electron microscope 1 is disposed on the top surface of the vacuum transfer sample stage 2 .

[0035] To further optimize the solution, a vacuum flange 3 is provided on the SEM-FIB dual-beam electron microscope 1 , and the electrodes on the solid-state battery fixture are connected to the wires on the vacuum flange 3 .

[0036] A further optimized solution is that the vacuum flange 3 is provided with an external wire connection port 4, the external wire connection port 4 is connected to one end of an electrochemical test external wire, and the other end of the electrochemical test external wire is electrically connected to an electrochemical test mechanism; the vacuum flange 3 is provided with two electrode wire interfaces 5, the electrode wire interface 5 is electrically connected to one end of an electrode external wire 6, and the other end of the electrode external wire 6 is electrically connected to the solid-state battery fixture.

[0037] Fix the vacuum transfer sample stage 2 adapted to the solid-state battery fixture on the SEM-FIB dual-beam electron microscope 1, and connect the electrodes on the vacuum transfer sample stage 2 to the electrochemical testing mechanism outside the electron microscope through the vacuum flange 3, and then evacuate the SEM-FIB dual-beam electron microscope 1; cut a flat cross section of the prepared solid-state battery, put the solid-state battery fixture into the glove box, and transfer it to the SEM-FIB dual-beam electron microscope 1 through the vacuum transfer sample stage 2.

[0038] According to a further optimized solution, the electrochemical test mechanism is a LAND test mechanism 7, and the LAND test mechanism 7 is electrically connected to an electrochemical test external lead.

[0039] A further optimized solution is that the solid-state battery fixture includes a fixture base 8, a groove 9 is provided in the fixture base 8, a screw rod 10 is threadedly connected to one side of the groove 9, a slider 11 is threadedly connected to the screw rod 10, the slider 11 is slidably connected in the groove 9, and a sample to be tested is provided at one end of the slider 11 away from the screw rod 10.

[0040] To further optimize the scheme, the sample to be tested is an all-solid-state battery, which is composed of a solid electrolyte and positive and negative electrode materials. Oxide inorganic solid electrolytes, such as garnet oxide electrolytes (Li7La3Zr2O 12 , Li 6.4 Ln3Z 1.4 Ta 0.6 O 12 etc.), perovskite oxide electrolytes (Li3xLa 2 / 3-x TiO3), sodium superion conductor oxide electrolyte (Li 1+x Al x Ti 2-x (PO4)3、Li1+ x Al x Ge 2-x (PO4)3); sulfide inorganic solid electrolytes, such as sulfide glass electrolytes, sulfide glass-ceramic electrolytes (0.7Li2S-0.3P2S5, 0.6Li2S-0.4SiS2, etc.), Li 10 MP2S 12 Group sulfide electrolytes (M = Ge, Sn, Si), argyrodite-type sulfide electrolytes (Li6PS5X, X = Cl, Br, I), etc.

[0041] The negative electrode is a metallic lithium negative electrode, a silicon negative electrode, a graphite negative electrode, a lithium titanate negative electrode and a silicon-carbon negative electrode.

[0042] The positive electrode includes lithium iron phosphate positive electrode, lithium cobalt oxide positive electrode, ternary layered oxide positive electrode, high voltage spinel positive electrode (LiMn2O4), lithium-rich manganese-based positive electrode, etc.

[0043] A method for using an in-situ SEM imaging and macroscopic battery testing system comprises the following steps:

[0044] A. Make test samples by using a powder tablet press;

[0045] B. Install the test sample and install the manufactured test sample into the solid-state battery fixture;

[0046] C. Place the solid-state battery fixture into the vacuum transfer mechanism;

[0047] D. Connect the solid-state battery fixture to the electrochemical testing mechanism;

[0048] E. Test the test samples; use a scanning electron microscope to record the microscopic morphology and structural evolution of the battery samples during the electrochemical test process; use a macro battery test system to synchronously record the electrochemical curve of the solid-state battery during the test to simulate the test conditions of the macro battery. Use analysis software to superimpose the morphological evolution process with the electrochemical curve to obtain high-resolution microscopic failure process imaging of the solid-state battery under macro electrochemical test conditions.

[0049] Example 1

[0050] In a glove box, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 (LSPSCl) solid electrolyte powder and Li 6.5 Ln3Z 1.5 Ta 0.5 O 12 (LLZTO) solid electrolyte powders are pressed together into sheets under a certain pressure and assembled into lithium batteries. After taking out the assembled battery, cut a flat cross section with a scalpel. The prepared sample to be tested is installed on the solid-state battery fixture in the glove box, and then the solid-state battery fixture is transferred to the SEM-FIB dual-beam electron microscope 1 using a vacuum transfer mechanism. After confirming that the circuit contact is good, the LAND test mechanism 7 is connected to the internal battery fixture through an external wire, and the LAND test program is set up. The scanning electron microscope is used for imaging to record the dendrite growth process of the two-phase electrolyte interface of the solid-state battery during the cycle. At the same time, the LAND test mechanism 7 records the voltage-time curve of the solid-state battery during the test.

[0051] By the attached Figure 2 It can be seen that lithium dendrites will grow near the LSPSCl / LLZTO solid electrolyte interface during the lithium insertion process. At the same time, the dendrite growth causes cracks in the electrolyte. With the growth of dendrites and the expansion of cracks, the battery will short-circuit. Figure 3It can be seen that during the failure of solid-state batteries, as the lithium insertion process proceeds, the polarization of the battery continues to increase, eventually leading to a battery short circuit.

[0052] Example 2

[0053] In a glove box, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 (LSPSCl) solid electrolyte powder and NMC811 powder are pressed into sheets together under a certain pressure, and an NMC / LSPSCl / Li all-solid-state battery is assembled. After taking out the assembled battery, cut a flat cross section with a scalpel. The prepared sample is mounted on a fixture in a glove box, and then the fixture is transferred to an electron microscope using a vacuum transfer device. After confirming that the circuit contact is good, the LAND test device is connected to the internal battery fixture through an external wire, and the LAND test program is set up. Scanning electron microscope imaging is used to record the dendrite growth process of the two-phase electrolyte interface during the cycle of the solid-state battery. At the same time, the LAND test system records the voltage-time curve of the solid-state battery during the test.

[0054] By the attached Figure 4 It can be seen that the NMC / LSPSCl / Li all-solid-state battery did not show dendrite growth during the cycle, and there was no crack in the electrolyte. The results show that the NMC / LSPSCl / Li all-solid-state battery has good stability during the cycle.

[0055] Example 3

[0056] In a glove box, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 (LSPSCl) solid electrolyte powder is pressed into sheets under a certain pressure, and a Li / LSPSCl / Li all-solid-state battery is assembled. After taking out the assembled battery, a flat cross-section is cut with a scalpel. The prepared sample is mounted on a fixture in a glove box, and then the fixture is transferred to an electron microscope using a vacuum transfer device. After confirming that the circuit contact is good, the LAND test device is connected to the internal battery fixture through an external wire, and the LAND test program is set up. Scanning electron microscope imaging is used to record the dendrite growth process at the two-phase electrolyte interface of the solid-state battery during the cycle. At the same time, the LAND test system records the voltage-time curve of the solid-state battery during the test.

[0057] By the attached Figure 5It can be seen that dendrite growth occurs in the Li / LSPSCl cross section of the Li / LSPSCl all-solid-state battery during the lithium insertion process, but no cracks appear in the electrolyte. The results show that the failure of the Li / LSPSCl / Li all-solid-state battery during the cycle may be related to the large-scale growth of dendrites at the interface.

[0058] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0059] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An in-situ SEM imaging and macroscopic battery testing system, characterized in that: The invention comprises a SEM-FIB dual-beam electron microscope (1), wherein the SEM-FIB dual-beam electron microscope (1) is fixedly connected to a vacuum transmission mechanism, a solid-state battery fixture is fixedly connected to the top of the vacuum transmission mechanism, the vacuum transmission mechanism is fixedly connected to the solid-state battery fixture, a sample to be tested is arranged in the solid-state battery fixture, and the solid-state battery fixture is electrically connected to an electrochemical testing mechanism.

2. The in-situ SEM imaging and macroscopic battery testing system according to claim 1, characterized in that: The vacuum transfer mechanism comprises a vacuum transfer sample stage (2), and the top surface of the vacuum transfer sample stage (2) is provided with the SEM-FIB double-beam electron microscope (1).

3. The in-situ SEM imaging and macroscopic battery testing system according to claim 2, characterized in that: The SEM-FIB dual-beam electron microscope (1) is provided with a vacuum flange (3), and the electrodes on the solid-state battery fixture are connected to the wires on the vacuum flange (3).

4. The in-situ SEM imaging and macroscopic battery testing system according to claim 3, characterized in that: The vacuum flange (3) is provided with an external wire connection port (4), the external wire connection port (4) is connected to one end of an electrochemical test external wire, and the other end of the electrochemical test external wire is electrically connected to the electrochemical test mechanism. The vacuum flange (3) is provided with two electrode wire interfaces (5), the electrode wire interface (5) is electrically connected to one end of an electrode external wire (6), and the other end of the electrode external wire (6) is electrically connected to the solid-state battery fixture.

5. The in-situ SEM imaging and macroscopic battery testing system according to claim 4, characterized in that: The electrochemical testing mechanism is a LAND testing mechanism (7), and the LAND testing mechanism (7) is electrically connected to the electrochemical testing external lead wire.

6. The in-situ SEM imaging and macroscopic battery testing system according to claim 1, characterized in that: The solid-state battery fixture comprises a fixture base (8), a groove (9) is provided in the fixture base (8), a screw rod (10) is threadedly connected to one side of the groove (9), a slider (11) is threadedly connected to the screw rod (10), the slider (11) is slidably connected in the groove (9), and the sample to be tested is provided at one end of the slider (11) away from the screw rod (10).

7. The in-situ SEM imaging and macroscopic battery testing system according to claim 1, characterized in that: The sample to be tested is an all-solid-state battery, which is composed of a solid electrolyte and positive and negative electrode materials of the all-solid-state battery.

8. A method for using an in-situ SEM imaging and macroscopic battery testing system, based on the in-situ SEM imaging and macroscopic battery testing system according to any one of claims 1 to 7, characterized in that: The following steps are involved: A. Make test samples by using a powder tablet press; B. Install the test sample and install the manufactured test sample into the solid-state battery fixture; C. Place the solid-state battery fixture into the vacuum transfer mechanism; D. Connect the solid-state battery fixture to the electrochemical testing mechanism; E. Test the test samples.

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