Raman device for detecting gas in battery

Abstract

The invention discloses a Raman device for detecting gas in a battery, which relates to the technical field of battery detection equipment and comprises a detection light emitting device, a spectrograph, a first light transmitting window and a second light transmitting window, the first light-transmitting window and the second light-transmitting window are used for being arranged on the wall face of a battery shell and connected with the wall face of the battery shell in a sealed mode, and the detection light emitting device can emit a detection light beam into the battery shell from the first light-transmitting window. And the spectrograph can receive scattered light emitted from the second light-transmitting window and perform chromatographic analysis. The method is high in detection precision, high in efficiency and low in cost.

Description

Technical Field

[0001] The present invention relates to the technical field of battery detection equipment, and in particular to a Raman device for detecting gas in a battery. Background Art

[0002] With the widespread use of energy storage power stations and electric vehicles, the problem of thermal runaway of lithium batteries has become increasingly prominent and has become a key factor affecting battery safety and reliability. During thermal runaway, combustible gases (such as H2, CO, CH4, etc.) will be violently released inside the battery, accompanied by a chain exothermic reaction, and the existing laboratory detection technology has serious limitations. Specifically, existing detection methods rely on gas sensors (electrochemical / semiconductor) or offline chromatography-mass spectrometry (GC-MS), which have slow response speeds (minutes), cannot be monitored in situ, and the sampling process is prone to changes in gas composition (such as oxidation and adsorption). Hysteresis defect: Existing methods can only capture the gas after the pressure relief valve is opened, that is, the gas released in the middle and late stages of thermal runaway. It is impossible to obtain gas evolution data in the early stage of thermal runaway, resulting in delayed warnings and difficulty in formulating effective active prevention and control strategies. Summary of the Invention

[0003] The purpose of the present invention is to provide a Raman device for detecting gas in a battery, so as to solve the problems existing in the above-mentioned prior art, and to have high detection accuracy, high efficiency and low cost.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a Raman device for detecting gas in a battery, comprising: a detection light emitting device, a spectrometer, a first light-transmitting window, and a second light-transmitting window. The first light-transmitting window and the second light-transmitting window are used to be arranged on the wall surface of a battery shell and to be sealed and connected to the wall surface of the battery shell. The detection light emitting device can emit a detection light beam into the battery shell through the first light-transmitting window, and the spectrometer can receive scattered light emitted from the second light-transmitting window and perform chromatographic analysis.

[0006] In some embodiments, the first light-transmitting window is used to be provided on a first wall surface of the battery housing in the circumferential direction, and the second light-transmitting window is used to be provided on a second wall surface of the battery housing in the circumferential direction adjacent to the first wall surface.

[0007] In some embodiments, it also includes a third light-transmitting window, a fourth light-transmitting window, a third reflection component and a fourth reflection component, the third light-transmitting window is used to be arranged on the third wall surface opposite to the first wall surface in the circumferential direction of the battery shell, and the fourth light-transmitting window is used to be arranged on the fourth wall surface opposite to the second wall surface in the circumferential direction of the battery shell; the third reflection component is arranged on the outside of the third light-transmitting window, and the fourth reflection component is arranged on the outside of the fourth light-transmitting window, the third reflection component can reflect the detection light beam emitted from the third light-transmitting window back into the battery shell and then emit it from the first light-transmitting window; the fourth reflection component can reflect the scattered light emitted from the fourth light-transmitting window back into the battery shell and then emit it from the second light-transmitting window.

[0008] In some embodiments, the detection beam is a laser.

[0009] In some embodiments, the detection light emitting device includes a laser, a first right-angle reflector and a first plane reflector; the first plane reflector, the first right-angle reflector and the laser are arranged in sequence along a direction parallel to the plane where the first light-transmitting window is located, the first plane reflector is directly opposite to the first light-transmitting window and the angle between the first plane reflector and the plane where the first light-transmitting window is located is 45°, a laser passage hole is provided at the right-angle end of the first right-angle reflector, the laser emitted by the laser is irradiated on the first plane reflector through the laser passage hole, the first plane reflector is used to reflect the laser along a direction perpendicular to the plane where the first light-transmitting window is located into the battery shell; the first plane reflector is also used to reflect the laser emitted from the first light-transmitting window onto the first right-angle reflector, the first right-angle reflector is used to emit the laser reflected from the first plane reflector back to the first plane reflector, and the first plane reflector is used to reflect the laser reflected from the first right-angle reflector back into the battery shell.

[0010] In some embodiments, the third reflective component includes a third right-angle reflector, and the angles between the two mirror surfaces of the third right-angle reflector and the plane where the third light-transmitting window is located are both 45°; the fourth reflective component includes a fourth plane reflector, and the fourth plane reflector is parallel to the plane where the fourth light-transmitting window is located.

[0011] In some embodiments, the first light-transmitting window, the second light-transmitting window, the fourth light-transmitting window and the fourth light-transmitting window all include a sapphire light-transmitting sheet and a fixing frame, one light-transmitting window corresponds to a through hole on the wall of the battery shell, the fixing frame is used to be fixed at the through hole and sealed to the wall, the sapphire light-transmitting sheet is fixed in the fixing frame and sealed to the fixing frame, and the fixing frame and the sapphire light-transmitting sheet jointly seal the through hole.

[0012] In some embodiments, the sapphire light-transmitting sheet and the fixing frame are connected by welding, and the fixing frame and the wall are connected by welding.

[0013] In some embodiments, an optical path bracket is further included, which is used to be arranged in the battery housing and located above the battery cell, and an optical path connecting the first light-transmitting window, the third light-transmitting window, the second light-transmitting window and the fourth light-transmitting window is formed in the optical path bracket.

[0014] In some embodiments, a filling block is further included, wherein the filling block is used to be arranged between the battery cell and the inner wall of the battery casing to limit the position of the battery cell.

[0015] Compared with the prior art, the present invention has achieved the following technical effects:

[0016] The Raman device for detecting gas in a battery provided by the present invention can directly obtain gas composition evolution data from the inside of the battery casing, and achieve millisecond-level response in the early stage of thermal runaway (temperature <100°C stage). In addition, the solution provided by the present invention does not require major changes to the original structure of the battery, such as the battery casing and battery cells. The original production line can be directly used to produce components such as the battery casing and battery cells. Then, a battery casing of a suitable size is selected to match a battery cell of a suitable size, and a light-transmitting window is installed after a hole is opened in the battery casing to construct a complete battery capable of detecting gas released from the battery cell, thereby improving efficiency and reducing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A schematic diagram of the overall optical path of the Raman device for detecting gas in a battery provided by the present invention;

[0019] Figure 2 This is a schematic diagram of the reconstructed overall battery structure;

[0020] Figure 3 for Figure 2 A top view of

[0021] Figure 4 for Figure 2 Schematic diagram of the internal structure of the battery shell;

[0022] Figure 5 for Figure 2 Structural explosion diagram;

[0023] Figure 6 for Figure 2 A vertical cross-sectional view of

[0024] In the figure: 1-detection light emitting device; 2-spectrometer; 3-third reflection component; 4-fourth reflection component.

[0025] 11-Laser; 12-First right-angle reflector; 13-First plane reflector.

[0026] 51 - first focusing lens; 52 - second focusing lens; 53 - first convex lens; 54 - second convex lens.

[0027] 61 - first light-transmitting window; 62 - second light-transmitting window; 63 - third light-transmitting window; 64 - fourth light-transmitting window; 65 - optical path bracket; 66 - sapphire light-transmitting sheet; 67 - fixing frame; 68 - optical path.

[0028] 71 - battery housing; 72 - battery cell; 73 - filling block; 74 - battery top cover; 75 - through hole. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] The purpose of the present invention is to provide a Raman device for detecting gas in a battery, so as to solve the problems existing in the prior art, and to have high detection accuracy, high efficiency and low cost.

[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] The following combination Figures 1 to 6 , describing embodiments of the present invention.

[0033] The present invention provides a Raman device for detecting gas in a battery. Figure 1 As shown, it includes: a detection light emitting device 1, a spectrometer 2, a first light-transmitting window 61 and a second light-transmitting window 62. The first light-transmitting window 61 and the second light-transmitting window 62 are used to be arranged on the wall of the battery housing 71 and are sealed and connected to the wall of the battery housing 71. The detection light emitting device 1 can emit a detection light beam from the first light-transmitting window 61 into the battery housing 71, and the spectrometer 2 can receive the scattered light emitted from the second light-transmitting window 62 and perform chromatographic analysis.

[0034] The Raman device for detecting gas in a battery provided in an embodiment of the present invention can directly obtain gas composition evolution data from the inside of the battery shell 71, and achieve millisecond-level response in the early stage of thermal runaway (temperature <100°C stage). The solution provided by the present invention does not require major changes to the original structure of the battery, such as the battery shell 71 and the battery cell 72. The original production line can be directly used to produce components such as the battery shell 71 and the battery cell 72. Then, a battery shell 71 larger than the battery cell 72 to be tested is selected to match the battery cell 72 to be tested, and a hole is opened in the battery shell 71 and a light-transmitting window is installed to construct a complete battery capable of detecting gas released by the battery cell 72, thereby improving detection efficiency and reducing costs.

[0035] In some embodiments, the first light-transmitting window 61 is provided on a first circumferential wall of the battery housing 71 , and the second light-transmitting window 62 is provided on a second circumferential wall of the battery housing 71 adjacent to the first wall.

[0036] In this embodiment, the detection beam incident from the first light-transmitting window 61 extends along the optical path 68 . The second light-transmitting window 62 is located on one side of the optical path 68 . The detection beam undergoes Raman scattering effect, and the scattered light is emitted from the second light-transmitting window 62 and received by the spectrometer 2 .

[0037] In some embodiments, the embodiments of the present invention also include a third light-transmitting window 63, a fourth light-transmitting window 64, a third reflective component 3 and a fourth reflective component 4, the third light-transmitting window 63 is used to be arranged on the third wall surface opposite to the first wall surface in the circumferential direction of the battery shell 71, and the fourth light-transmitting window 64 is used to be arranged on the fourth wall surface opposite to the second wall surface in the circumferential direction of the battery shell 71; the third reflective component 3 is arranged on the outside of the third light-transmitting window 63, and the fourth reflective component 4 is arranged on the outside of the fourth light-transmitting window 64, the third reflective component 3 can reflect the detection light beam emitted from the third light-transmitting window 63 back into the battery shell 71 and then emit it from the first light-transmitting window 61; the fourth reflective component 4 can reflect the scattered light emitted from the fourth light-transmitting window 64 back into the battery shell 71 and then emit it from the second light-transmitting window 62.

[0038] The embodiment of the present invention improves the signal intensity through reflection by the third reflection component 3 and the fourth reflection component 4, realizes focusing of light inside the battery, lowers the detection limit, enhances the Raman signal at this point inside the battery shell 71, and realizes high-precision and rapid detection inside the battery shell 71 at normal pressure.

[0039] In some embodiments, the detection beam is a laser.

[0040] Principle of Raman spectroscopy detection using laser:

[0041] Raman spectroscopy is based on the Raman scattering effect. When monochromatic laser light (frequency ν0) interacts with gas molecules, photons collide inelastically with the molecules, causing a shift in the photon frequency (Raman shift Δν), which is mathematically expressed as:

[0042] Δν=ν0-ν 散射

[0043] The Raman shift is directly related to the molecular vibrational / rotational energy levels and is the "fingerprint" characteristic of the gas composition. The Raman signal intensity (I) is proportional to the gas concentration (C), laser power (P) and the square of the molecular polarizability (α), satisfying:

[0044] I∝P·C·α 2 .

[0045] In some embodiments, the detection light emitting device 1 includes a laser 11, a first right-angle reflector 12 and a first plane reflector 13; the first plane reflector 13, the first right-angle reflector 12 and the laser 11 are arranged in sequence along a direction parallel to the plane where the first light-transmitting window 61 is located, the first plane reflector 13 is directly opposite to the first light-transmitting window 61 and the angle between the first plane reflector 13 and the plane where the first light-transmitting window 61 is located is 45°, a laser passing hole is provided at the right-angle end of the first right-angle reflector 12, and the laser emitted by the laser 11 passes through the laser passing hole to illuminate the laser. The laser is projected onto the first plane reflector 13, and the first plane reflector 13 is used to reflect the laser into the battery housing 71 along a direction perpendicular to the plane where the first light-transmitting window 61 is located; the first plane reflector 13 is also used to reflect the laser emitted from the first light-transmitting window 61 onto the first right-angle reflector 12, and the first right-angle reflector 12 is used to emit the laser reflected from the first plane reflector 13 back to the first plane reflector 13, and the first plane reflector 13 is used to reflect the laser reflected from the first right-angle reflector 12 back into the battery housing 71.

[0046] This embodiment significantly improves the signal strength through multi-level reflection of the first right-angle reflector 12 and the third emitting component, further reduces the detection limit, and further focuses the light inside the battery shell 71. It can further enhance the Raman signal at this point inside the battery shell 71, and achieve high-precision and rapid detection inside the battery shell 71 under normal pressure.

[0047] In some embodiments, a first focusing lens 51 is further provided between the first light-transmitting window 61 and the first plane reflector 13, and a second focusing lens 52 is further provided between the third light-transmitting window 63 and the third reflective assembly 3. A first convex lens 53 and a second convex lens 54 are sequentially provided outside the second light-transmitting window 62.

[0048] In this embodiment, the first focusing mirror 51 and the second focusing mirror 52 are used to focus the detection light beams entering the battery housing 71 from the first light-transmitting window 61 and the third light-transmitting window 63 to a single point, which is the center in the longitudinal direction of the battery housing 71. The first convex lens 53 is used to collimate the scattered light from the second light-transmitting window 62, and the second convex lens 54 is used to focus the scattered light to the light receiving end of the spectrometer 2.

[0049] In some embodiments, the third reflective component 3 includes a third right-angle reflector, and the angles between the two mirror surfaces of the third right-angle reflector and the plane where the third light-transmitting window 63 is located are both 45°; the fourth reflective component 4 includes a fourth plane reflector, and the fourth plane reflector is parallel to the plane where the fourth light-transmitting window 64 is located.

[0050] This embodiment provides a possible implementation method of the third reflective component 3 and the fourth reflective component 4 .

[0051] In some embodiments, the first light-transmitting window 61, the second light-transmitting window 62, the fourth light-transmitting window 64 and the fourth light-transmitting window 64 all include a sapphire light-transmitting sheet 66 and a fixing frame 67. One light-transmitting window corresponds to a through hole 75 on the wall of a battery shell 71. The fixing frame 67 is used to be fixed at the through hole 75 and sealed to the wall. The sapphire light-transmitting sheet 66 is fixed in the fixing frame 67 and sealed to the fixing frame 67. The fixing frame 67 and the sapphire light-transmitting sheet 66 jointly seal the through hole 75. Specifically, the sapphire light-transmitting sheet 66 and the fixing frame 67 are welded together, and the fixing frame 67 and the wall are welded together.

[0052] This embodiment provides a method for sealingly connecting the light-transmitting window to the wall of the battery shell 71. It can be understood that the weld between the fixed frame 67 and the wall is a closed ring structure, and the weld between the fixed frame 67 and the sapphire light-transmitting sheet 66 is also a closed ring structure, so that the purpose of sealing connection can be achieved.

[0053] Of course, in some examples, the sapphire light-transmitting sheet 66 can also be directly welded to the wall of the battery shell 71, but since the fixing frame 67 and the battery shell 71 are usually made of metal materials, such as stainless steel alloy materials, and the sapphire light-transmitting sheet 66 is a non-metallic material, the welding between the sapphire light-transmitting sheet 66 and the metal material needs to be carried out using a dissimilar material welding process. Compared with the welding of metal materials, the dissimilar material welding process is more complicated and has high requirements. Taking this situation into consideration, the present invention can pre-weld the sapphire light-transmitting sheet 66 to the fixing frame 67 using special equipment and a dissimilar material welding process, and then when inspection is required, the fixing frame 67 can be directly welded to the wall of the battery shell 71 using a metal welding process.

[0054] In addition to the above welding scheme, when the light-transmitting window is required to be detachable, the light-transmitting window can also be connected to the wall of the battery housing 71 by bolts and nuts. When bolts and nuts are used for connection, a sealing gasket needs to be provided to seal the connection.

[0055] In some embodiments, since the specifications of the battery shell 71 are usually larger than those of the battery cell 72, and the battery shell 71 needs to be equipped with a pole ear connected to the battery cell 72, the arrangement of the pole ear can easily block the light path 68. Therefore, the embodiment of the present invention also includes a light path bracket 65, which is used to be arranged in the battery shell 71 and above the battery cell 72. An optical path 68 connecting the first light-transmitting window 61, the third light-transmitting window 63, the second light-transmitting window 62 and the fourth light-transmitting window 64 is formed in the light path bracket 65. The optical path 68 can also be called a Raman cell.

[0056] In this embodiment, the tab is located above the optical path bracket 65. The optical path bracket 65 is provided on the one hand to prevent the tab from interfering with the propagation of the light path inside the battery shell 71, and on the other hand to reduce the cavity volume inside the battery to a certain extent, reduce the volatilization of the electrolyte in the battery cell 72, and increase the gas concentration at the optical path, thereby further improving the detection accuracy.

[0057] It should be noted that the optical path in the optical path bracket 65 needs to be connected to the space where the battery cell 72 is located, so that the gas released by the battery cell 72 can enter the optical path.

[0058] In some embodiments, the present invention further includes a filling block 73 , which is used to be disposed between the battery cell 72 and the inner wall of the battery housing 71 to limit the position of the battery cell 72 .

[0059] The filling block 73 in this embodiment is used to fix the position of the battery cell 72 on the one hand, and on the other hand it can also reduce the volume of the cavity inside the battery shell 71, thereby reducing the volatilization of the electrolyte in the battery cell 72 and increasing the gas concentration in the optical path, thereby further improving the detection accuracy.

[0060] It should be noted that during the detection, the battery can be detected in a charging state, a discharging state or an idle state.

[0061] In some embodiments, when testing a 50Ah lithium iron phosphate battery cell, the battery shell may adopt a 280Ah battery shell, which includes a 280Ah battery top cover, the battery top cover 74 is provided with a liquid injection hole, a pressure relief valve and a pole, and a pole ear is integrated under the battery top cover 74.

[0062] In some embodiments, a light shield is also included, which covers the outside of the battery shell and is used to block external light to avoid interference with the detection process. The light shield is provided with a hole structure to cooperate with the structure on the battery. For example, a hole structure is provided at the position corresponding to the position of the light-transmitting window and the position of the electrode to facilitate the entry and exit of the optical fiber and the lead-out of the positive and negative circuits.

[0063] In some embodiments, a power supply device is further included to charge the battery cells.

[0064] 1. Low-loss in-situ real-time gas Raman detection:

[0065] Compared with existing technologies (such as implanted fiber optic probes or external pressurized gas detection devices), this product's battery-Raman cell co-integrated design has better sealing performance and in-situ detection fidelity.

[0066] Improved sealing performance: The sapphire transparent sheet 66 is welded with stainless steel alloy to form a fully enclosed and leak-free structure, which can withstand extreme conditions of thermal runaway (pressure resistance > 1MPa) and avoid gas escape or external contamination.

[0067] In-situ detection fidelity: The laser directly penetrates the sapphire transparent sheet 66 (transmittance>99.5%) to stimulate the gas inside the battery shell 71, eliminating the composition distortion caused by external gas conduction (such as oxidation and adsorption), and reflecting the dynamic changes of the gas in real time (response delay<1s). The gas composition inside the battery shell 71 is directly detected, which can more accurately and timely describe the type and composition of the gas inside the battery.

[0068] 2. High-precision and fast detection dual modes in parallel:

[0069] Signal enhancement design: By designing a right-angle reflector to reflect the light path multiple times (extending the optical path to 10 times that of the traditional design), combined with the focusing of the focusing mirror, the Raman signal intensity is increased by more than 5 times.

[0070] Dynamic detection mode: Long cycle high-precision mode (integration time 60s): The detection limit is as low as 500ppm, suitable for battery cycle life testing; Thermal runaway fast mode (integration time 0.5s): Capture gas mutations (such as H2 and CO concentration surges) in milliseconds, and then set the gas sensors and alarm thresholds in the service battery by studying the gas mutation information, thereby meeting early warning needs.

[0071] 3. Low-cost architecture:

[0072] Compatible with existing production lines: Customized processing based on universal battery sizes, no need to modify the battery structure, only surface drilling is required to achieve large-scale application.

[0073] 4. Sources of Advantage

[0074] Common packaging technology: dissimilar metal welding eliminates interface thermal stress and ensures structural stability under extreme working conditions;

[0075] Optical-mechanical-electrical collaborative design: Optimizes optical signal transmission paths through multi-level reflective optical paths, combined with background noise subtraction technology to effectively achieve signal gain and noise suppression.

[0076] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A Raman device for detecting gas in a battery, characterized by: include: A detection light emitting device, a spectrometer, a first light-transmitting window and a second light-transmitting window, wherein the first light-transmitting window and the second light-transmitting window are used to be arranged on the wall surface of the battery housing and to be sealed with the wall surface of the battery housing; the detection light emitting device can emit a detection light beam into the battery housing from the first light-transmitting window; and the spectrometer can receive scattered light emitted from the second light-transmitting window and perform chromatographic analysis.

2. The Raman device for detecting gas in a battery according to claim 1, characterized in that: The first light-transmitting window is used to be arranged on a first wall surface of the battery housing in the circumferential direction, and the second light-transmitting window is used to be arranged on a second wall surface of the battery housing in the circumferential direction adjacent to the first wall surface.

3. The Raman device for detecting gas in a battery according to claim 2, characterized in that: It also includes a third light-transmitting window, a fourth light-transmitting window, a third reflection component and a fourth reflection component, the third light-transmitting window is used to be arranged on the third wall surface opposite to the first wall surface in the circumferential direction of the battery shell, and the fourth light-transmitting window is used to be arranged on the fourth wall surface opposite to the second wall surface in the circumferential direction of the battery shell; the third reflection component is arranged on the outside of the third light-transmitting window, and the fourth reflection component is arranged on the outside of the fourth light-transmitting window, and the third reflection component can reflect the detection light beam emitted from the third light-transmitting window back into the battery shell and then emit it from the first light-transmitting window; the fourth reflection component can reflect the scattered light emitted from the fourth light-transmitting window back into the battery shell and then emit it from the second light-transmitting window.

4. The Raman device for detecting gas in a battery according to claim 3, characterized in that: The detection light beam is a laser.

5. The Raman device for detecting gas in a battery according to claim 4, characterized in that: The detection light emitting device includes a laser, a first right-angle reflector and a first plane reflector; the first plane reflector, the first right-angle reflector and the laser are arranged in sequence along a direction parallel to the plane where the first light-transmitting window is located, the first plane reflector is directly opposite to the first light-transmitting window and the angle between the first plane reflector and the plane where the first light-transmitting window is located is 45°, a laser passage hole is provided at the right-angle end of the first right-angle reflector, the laser emitted by the laser is irradiated on the first plane reflector through the laser passage hole, the first plane reflector is used to reflect the laser along a direction perpendicular to the plane where the first light-transmitting window is located into the battery shell; the first plane reflector is also used to reflect the laser emitted from the first light-transmitting window onto the first right-angle reflector, the first right-angle reflector is used to emit the laser reflected from the first plane reflector back to the first plane reflector, and the first plane reflector is used to reflect the laser reflected from the first right-angle reflector back into the battery shell.

6. The Raman device for detecting gas in a battery according to claim 5, characterized in that: The third reflective assembly includes a third right-angle reflector, and the angles between the two mirror surfaces of the third right-angle reflector and the plane where the third light-transmitting window is located are both 45°; the fourth reflective assembly includes a fourth plane reflector, and the fourth plane reflector is parallel to the plane where the fourth light-transmitting window is located.

7. The Raman device for detecting gas in a battery according to claim 3, characterized in that: The first light-transmitting window, the second light-transmitting window, the fourth light-transmitting window and the fourth light-transmitting window all include a sapphire light-transmitting sheet and a fixing frame. One light-transmitting window corresponds to a through hole on the wall of the battery shell. The fixing frame is used to be fixed at the through hole and sealed to the wall. The sapphire light-transmitting sheet is fixed in the fixing frame and sealed to the fixing frame. The fixing frame and the sapphire light-transmitting sheet jointly seal the through hole.

8. The Raman device for detecting gas in a battery according to claim 7, characterized in that: The sapphire light-transmitting sheet and the fixing frame are connected by welding, and the fixing frame and the wall surface are connected by welding.

9. The Raman device for detecting gas in a battery according to claim 3, characterized in that: It also includes an optical path bracket, which is used to be arranged in the battery shell and located above the battery cell, and an optical path connecting the first light-transmitting window, the third light-transmitting window, the second light-transmitting window and the fourth light-transmitting window is formed in the optical path bracket.

10. The Raman device for detecting gas in a battery according to claim 9, characterized in that: It also includes a filling block and a light shield, wherein the filling block is used to be arranged between the battery cell and the inner wall of the battery shell to limit the position of the battery cell, and the light shield covers the outside of the battery shell.

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