Temperature-controlled graded curing and low-stress rolling method for FBG sensor electrode implantation

Abstract

This invention provides a method for implanting FBG (Fiber Optic Generative Gradient) sensors into electrode sheets using temperature-controlled graded curing and low-stress rolling, relating to the field of power battery manufacturing technology. The method involves attaching FBG optical fibers to the electrode sheet via an adhesive layer according to a preset wiring path, sequentially undergoing temperature-controlled pre-curing, multi-stage progressive rolling, and temperature-controlled final curing. This results in high bonding strength and strong integration reliability between the FBG optical fibers and the electrode sheet. While avoiding FBG optical fiber detachment, slippage, and breakage, the implantation process involves no grooving, drilling, or etching operations, preserving the electrode sheet coating and current collector, effectively ensuring the integrity of the cell structure and electrochemical performance. This results in an extremely low damage rate for both the FBG optical fibers and the electrode sheet. Furthermore, the process steps are simple, parameters are controllable, and it is compatible with large-scale power battery production lines, enabling high-efficiency mass production and cost reduction.

Description

Technical Field

[0001] This invention relates to the field of power battery manufacturing technology, specifically to a method for implanting FBG sensor electrodes using temperature-controlled graded curing and low-stress rolling. Background Technology

[0002] With the rapid development of the new energy vehicle industry, lithium-ion power batteries, as core power components, have seen their energy density, cycle life, safety performance, and intelligent monitoring level become key factors restricting the improvement of overall vehicle performance. To achieve in-situ, real-time, and accurate monitoring of key state parameters such as internal temperature, strain, and pressure of the battery, fiber Bragg grating (FBG) sensing technology, with its advantages of anti-electromagnetic interference, small size, high measurement accuracy, ability to achieve distributed multi-point detection, and good long-term stability, is gradually becoming an important technological direction for sensing the internal state of power batteries.

[0003] Currently, conventional methods for integrating FBG sensors into power batteries mainly include external cell attachment, electrode surface bonding, and mechanical grooving or drilling for embedding. However, all of these methods have significant drawbacks in practical applications, as follows: The method of attaching the battery cell to the outside cannot reflect the true electrochemical and mechanical state of the electrode body, and the detection signal is lagging and has a large error. The method of bonding the electrode surface to the optical fiber can easily lead to detachment, slippage or breakage during battery winding, stacking, electrolyte injection and charge-discharge cycles, resulting in monitoring failure. Mechanical grooving or drilling can directly damage the coating structure and current collector integrity of the battery electrode, causing problems such as active material shedding, obstruction of ion transport channels, and local stress concentration, which in turn can lead to safety risks such as battery capacity decay, reduced rate performance, lithium plating, and even internal short circuits.

[0004] Meanwhile, existing implantation processes generally suffer from poor compatibility with large-scale production lines for power batteries, irreversible damage to the electrode sheets during the implantation process, insufficient stability of the interface between the optical fiber and the electrode sheet, and difficulty in guaranteeing monitoring accuracy. These issues fail to meet the actual engineering requirements of high integration, high safety, long lifespan, and intelligent online monitoring for power batteries in new energy vehicles.

[0005] Therefore, in view of the pain points of existing technologies such as easy damage to battery electrodes, low integration reliability, and difficulty in mass production when FBG sensors are implanted into battery electrodes, there is an urgent need to develop a non-destructive, efficient, and stable method for implanting FBG sensors into battery electrodes. This method should achieve reliable integration of FBG sensors and battery electrodes without compromising the structural integrity and electrochemical performance of the electrodes, thereby providing technical support for accurate monitoring of the internal state of power batteries and early warning of thermal runaway. Summary of the Invention

[0006] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for embedding FBG sensors into battery electrodes using temperature-controlled graded curing and low-stress rolling, which solves the problems of electrode damage, low integration reliability, and difficulty in mass production when embedding FBG sensors into battery electrodes.

[0007] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: A method for implanting electrodes into FBG sensors using temperature-controlled graded curing and low-stress rolling, the method comprising: S1. Apply glue to a clean glass plate surface to form a uniform glue layer, and completely immerse the FBG optical fiber implant segment into the glue layer; S2. The non-implanted segments at both ends of the FBG fiber extend out of the adhesive layer. Fix the non-implanted segment at one end of the FBG fiber to the glass plate with tape. Use clean tweezers to adjust the FBG fiber, which has been soaked in adhesive, to the wiring position according to the preset path. Cover the FBG fiber with the electrode plate so that the FBG fiber is attached to the surface of the electrode plate according to the preset wiring path. Fix the non-implanted segment at the other end of the FBG fiber to the glass plate with tape, keeping the FBG fiber in a straight and tension-free state. S3. The glass plate carrying the bonding components is moved into a vacuum drying oven for pre-curing treatment; the adhesive layer is initially solidified; the bonding components include: electrode sheet, FBG optical fiber and adhesive layer; S4. Remove the pre-cured adhesive assembly from the glass plate and perform an initial roll press on the adhesive assembly using a roll press with a precisely adjustable roll gap. The roll gap of the initial roll press is slightly smaller than the thickness of the adhesive assembly. Then, the roll gap size is reduced to perform a second roll pressing on the adhesive component. This operation is repeated, and the roll gap size is gradually reduced in multiple stages to perform multiple cycles of roll pressing on the adhesive component until the thickness of the adhesive component reaches the target value. S5. Place the roll-formed bonding assembly on a clean glass plate, and use tape to fix the non-implanted sections at both ends of the FBG optical fiber to the glass plate; move the glass plate carrying the bonding assembly back into the vacuum drying oven for final curing, so that the adhesive is completely cured, and obtain the finished electrode with implanted FBG optical fiber.

[0008] Preferably, the method further includes: S6. Remove the electrode of the implanted FBG fiber that has been cured and transfer it to the glove box. Use a light tester to connect the two ends of the FBG fiber to test the continuity of the FBG fiber and confirm that the FBG fiber has not been broken or excessively damaged during the implantation process.

[0009] Preferably, the method further includes: After the S7.FBG fiber optic path performance test is passed, the FBG fiber is connected to the fiber optic grating demodulator to realize the implantation of the FBG sensor on the electrode.

[0010] Preferably, the adhesive is an AB type component adhesive that is uniformly mixed in a 2:1 ratio.

[0011] Preferably, in step S3, the vacuum degree in the vacuum drying oven is -0.11 to -0.09 MPa, the pre-curing temperature is 55 to 60°C, and the pre-curing time is 15 to 20 minutes.

[0012] Preferably, in step S4, the roll gap size is adjusted by 4~6µm each time.

[0013] Preferably, in step S5, the vacuum degree in the vacuum drying oven is -0.11 to -0.09 MPa, the final curing temperature is 65 to 70°C, and the final curing time is 25 to 30 minutes.

[0014] (III) Beneficial Effects This invention provides a method for implanting electrodes into FBG sensors using temperature-controlled graded curing and low-stress rolling. Compared with existing technologies, it has the following advantages: In this invention, the method uses an adhesive layer to bond FBG optical fibers to the electrode surface according to a preset wiring path, sequentially undergoing temperature-controlled pre-curing, multi-stage progressive rolling, and temperature-controlled final curing. This results in high bonding strength and strong integration reliability between the FBG optical fibers and the electrode. While avoiding FBG optical fiber detachment, slippage, and breakage, the implantation process involves no grooving, drilling, or etching operations, thus preserving the electrode coating and current collector and effectively ensuring the integrity of the cell structure and electrochemical performance. This results in extremely low damage rates to the FBG optical fibers and the electrode. Furthermore, the process steps are simple, the parameters are controllable, and it is compatible with large-scale production lines for power batteries, enabling high-efficiency mass production and cost reduction. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, 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.

[0016] Figure 1 This is a flowchart of the FBG sensor electrode implantation method in an embodiment of the present invention.

[0017] Figure 2 This is a demonstration diagram of the FBG optical fiber impregnation adhesive in an embodiment of the present invention.

[0018] Figure 3This is a schematic diagram of the FBG optical fiber and the electrode plate bonding structure in an embodiment of the present invention.

[0019] Figure 4 This is a schematic diagram of the structure of the roller press for rolling the adhesive assembly in an embodiment of the present invention.

[0020] Figure 5 This is a graph showing the capacity change trend after the electrode with embedded FBG optical fiber in Example 1 was made into a soft-pack battery and a charge-discharge cycle test was carried out.

[0021] Figure 6 This is a graph showing the capacity change trend after the electrode with embedded FBG optical fiber in Example 2 was made into a soft-pack battery and subjected to charge-discharge cycle testing.

[0022] Figure 7 This is a graph showing the capacity change trend after the electrode with embedded FBG optical fiber in Example 2 was made into a soft-pack battery and subjected to charge-discharge cycle testing. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This application provides a method for implanting FBG sensors into battery electrodes using temperature-controlled graded curing and low-stress rolling, which solves the problems of electrode damage, low integration reliability, and difficulty in mass production when implanting FBG sensors into battery electrodes.

[0025] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods. Example

[0026] like Figures 1-4 As shown, this invention provides a method for implanting electrodes into FBG sensors using temperature-controlled graded curing and low-stress rolling, the method comprising: S1. Optical fiber immersion Apply glue to the clean glass plate 1 surface to form a uniform glue layer 2. According to the preset implantation length, completely immerse the implantation section of FBG optical fiber 3 into the glue layer 2 to ensure that the surface of the bonding part is uniformly coated with glue. S2. Bonding of optical fiber and electrode sheet The non-implanted segments at both ends of the FBG fiber 3 extend out of the adhesive layer 2. The non-implanted segment at one end of the FBG fiber 3 is fixed to the glass plate 1 with adhesive tape 4. Using clean tweezers, the FBG fiber 3, which has been soaked in adhesive, is adjusted to the wiring position according to the preset path. The electrode 5 is covered on the FBG fiber 3, so that the FBG fiber 3 is attached to the surface of the electrode 5 according to the preset wiring path. The non-implanted segment at the other end of the FBG fiber 3 is fixed to the glass plate 1 with adhesive tape 4, keeping the FBG fiber 3 in a straight and tension-free state. The FBG fiber 3 is accurately positioned, flexibly protected, interface optimized and the electrode performance guaranteed through adhesive pre-curing. S3. Pre-curing treatment The glass plate 1 carrying the bonding components is moved into a vacuum drying oven for pre-curing treatment. The bonding components include: electrode 5, FBG optical fiber 3 and adhesive layer 2. The adhesive layer 2 is initially solidified, and the pre-cured adhesive layer 2 is maintained in a medium temperature environment to protect the positioning and electrode performance. S4. Multi-segment roll forming The pre-cured adhesive assembly is removed from the glass plate 1, and the adhesive assembly is initially rolled using a roller press 6 with a roller gap that can be precisely adjusted. The roller gap of the initial roll is slightly smaller than the thickness of the adhesive assembly. Then, the roll gap size is reduced to perform a second roll pressing on the adhesive component. This operation is repeated, and the roll gap size is gradually reduced in multiple stages to perform multiple cycles of roll pressing on the adhesive component until the thickness of the adhesive component reaches the target value. Segmented rolling achieves stress dispersion and high-precision bonding through step-by-step pressure application, improving process fault tolerance and protecting FBG optical fiber 3; S5. Final curing treatment The roll-formed adhesive assembly is placed on a clean glass plate 1, and the non-implanted sections at both ends of the FBG optical fiber 3 are fixed to the glass plate 1 using tape 4. The glass plate 1 carrying the adhesive assembly is then moved into a vacuum drying oven for final curing, so that the adhesive is completely cured, and the electrode 5 with the FBG optical fiber 3 implanted is obtained. The adhesive layer 2 is completely cured by using an adaptive medium-temperature final drying, which ensures the bonding strength and does not damage the structure.

[0027] The method further includes: S6. Path Performance Test Remove the electrode 5 of the implanted FBG fiber 3 after curing, transfer it to the glove box, and use a light tester to connect the two ends of the FBG fiber 3 to test the continuity of the FBG fiber 3 and confirm that the FBG fiber 3 has not been broken or excessively damaged during the implantation process. S7.FBG sensor access After the FBG fiber 3 path performance test is passed, the FBG fiber 3 is connected to the fiber grating demodulator to realize the implantation of the FBG sensor in the electrode 5.

[0028] The adhesive is an AB type component adhesive mixed evenly in a 2:1 ratio.

[0029] In S3, the vacuum degree in the vacuum drying oven is -0.1 MPa, the pre-curing temperature is 55°C, and the pre-curing time is 20 min.

[0030] In S4, the roll gap size is reduced by 4µm each time.

[0031] In S5, the vacuum degree in the vacuum drying oven is -0.1 MPa, the final curing temperature is 65°C, and the final curing time is 30 min.

[0032] In this embodiment, the electrode 5 with the embedded FBG optical fiber 3 is fabricated into a pouch battery, and charge-discharge cycle tests are conducted. Discharge capacity is used as the core evaluation indicator, and the capacity change trend during the cycle is recorded. Figure 5 As shown; the test results show that the discharge capacity of the battery assembled with the electrode 5 implanted with FBG optical fiber 3, which is manufactured using the process of this embodiment, remains within the normal and reasonable range of conventional batteries during long-term cycling, with stable capacity fluctuations and no significant attenuation; at the same time, the implanted FBG optical fiber 3 can collect the internal state parameters of the battery in real time, and realize online monitoring of the internal working condition of the soft pack battery without damaging the battery performance. Example

[0033] The difference from Example 1 is as follows: In S3, the vacuum degree in the vacuum drying oven is -0.09 MPa, the pre-curing temperature is 57.5℃, and the pre-curing time is 17.5 min.

[0034] In S4, the roll gap size is reduced by 5µm each time.

[0035] In S5, the vacuum degree in the vacuum drying oven is -0.09 MPa, the final curing temperature is 67.5℃, and the final curing time is 27.5 min.

[0036] In this embodiment, the electrode 5 with the embedded FBG optical fiber 3 is fabricated into a pouch battery, and charge-discharge cycle tests are conducted. Discharge capacity is used as the core evaluation indicator, and the capacity change trend during the cycle is recorded. Figure 6 As shown; the test results show that the discharge capacity of the battery assembled with the electrode 5 implanted with FBG optical fiber 3, which is manufactured using the process of this embodiment, remains within the normal and reasonable range of conventional batteries during long-term cycling, with stable capacity fluctuations and no significant attenuation; at the same time, the implanted FBG optical fiber 3 can collect the internal state parameters of the battery in real time, and realize online monitoring of the internal working condition of the soft pack battery without damaging the battery performance. Example

[0037] The difference from Example 1 is as follows: In S3, the vacuum degree in the vacuum drying oven is -0.11 MPa, the pre-curing temperature is 60°C, and the pre-curing time is 15 min.

[0038] In S4, the roll gap size is reduced by 6µm each time.

[0039] In S5, the vacuum degree in the vacuum drying oven is -0.11 MPa, the final curing temperature is 70°C, and the final curing time is 25 min.

[0040] In this embodiment, the electrode 5 with the embedded FBG optical fiber 3 is fabricated into a pouch battery, and charge-discharge cycle tests are conducted. Discharge capacity is used as the core evaluation indicator, and the capacity change trend during the cycle is recorded. Figure 7 As shown; the test results show that the discharge capacity of the battery assembled with the electrode 5 implanted with FBG optical fiber 3, which is manufactured using the process of this embodiment, remains within the normal and reasonable range of conventional batteries during long-term cycling, with stable capacity fluctuations and no significant attenuation; at the same time, the implanted FBG optical fiber 3 can collect the internal state parameters of the battery in real time, and realize online monitoring of the internal working condition of the soft pack battery without damaging the battery performance.

[0041] In summary, compared with the prior art, the present invention has the following beneficial effects: 1. In this embodiment of the invention, the implantation of FBG optical fiber does not require structural modifications such as slotting or drilling of the battery electrode, and will not cause significant damage to the electrode structure; no changes are required to the electrode structure, and FBG optical fiber integration is achieved only through bonding and curing, which can preserve the original structure and integrity of the electrode to the greatest extent.

[0042] 2. In this embodiment of the invention, the soft-pack battery assembled with the electrode plate implanted with FBG optical fiber has no significant difference in core performance such as charge / discharge capacity and cycle stability compared with the original soft-pack battery, and the battery performance remains within a reasonable range; at the same time, the implanted optical fiber can collect the internal state parameters of the battery in real time, and realize online monitoring of the internal working condition of the soft-pack battery without damaging the battery performance.

[0043] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0044] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for implanting electrodes into FBG sensors using temperature-controlled graded curing and low-stress rolling, characterized in that, The method includes: S1. Apply glue to the clean glass plate (1) surface to form a uniform glue layer (2), and completely immerse the implanted segment of FBG optical fiber (3) into the glue layer (2); S2. The non-implanted segments at both ends of the FBG fiber (3) extend out of the adhesive layer (2). Fix the non-implanted segment at one end of the FBG fiber (3) to the glass plate (1) with adhesive tape (4). Use clean tweezers to adjust the wiring position of the FBG fiber (3) that has been soaked in adhesive according to the preset path. Cover the FBG fiber (3) with the electrode plate (5) so that the FBG fiber (3) is attached to the surface of the electrode plate (5) according to the preset wiring path. Fix the non-implanted segment at the other end of the FBG fiber (3) to the glass plate (1) with adhesive tape (4) to keep the FBG fiber (3) in a straight and tension-free state. S3. The glass plate (1) carrying the bonding components is moved into a vacuum drying oven for pre-curing treatment; the adhesive layer (2) is initially solidified; the bonding components include: electrode (5), FBG optical fiber (3) and adhesive layer (2); S4. Remove the pre-cured adhesive assembly from the glass plate (1) and use a roller press (6) with a roller gap that can be precisely adjusted to perform the initial roller press on the adhesive assembly. The roller gap of the initial roller press is slightly smaller than the thickness of the adhesive assembly. Then, the roll gap size is reduced to perform a second roll pressing on the adhesive component. This operation is repeated, and the roll gap size is gradually reduced in multiple stages to perform multiple cycles of roll pressing on the adhesive component until the thickness of the adhesive component reaches the target value. S5. Place the roll-formed adhesive assembly on a clean glass plate (1), and use tape (4) to fix the non-implanted sections at both ends of the FBG optical fiber (3) on the glass plate (1); move the glass plate (1) carrying the adhesive assembly back into the vacuum drying oven for final curing, so that the glue is completely cured, and obtain the finished electrode (5) with the FBG optical fiber (3) implanted.

2. The method for implanting FBG sensor electrodes using temperature-controlled graded curing and low-stress rolling as described in claim 1, characterized in that, The method further includes: S6. Take out the electrode (5) of the implanted FBG fiber (3) after curing, transfer it to the glove box, connect the two ends of the FBG fiber (3) with a light tester, test the continuity of the FBG fiber (3), and confirm that the FBG fiber (3) has not been broken or excessively damaged during the implantation process.

3. The method for implanting FBG sensor electrodes using temperature-controlled graded curing and low-stress rolling as described in claim 2, characterized in that... The method further includes: After the S7.FBG fiber (3) passes the path performance test, the FBG fiber (3) is connected to the fiber optic demodulator to realize the FBG sensor implantation of the electrode (5).

4. The method for implanting FBG sensor electrodes using temperature-controlled graded curing and low-stress rolling as described in claim 1, characterized in that... The adhesive is an AB type component adhesive mixed evenly in a 2:1 ratio.

5. The method for implanting FBG sensor electrodes using temperature-controlled graded curing and low-stress rolling as described in claim 1, characterized in that... In S3, the vacuum degree in the vacuum drying oven is -0.11 to -0.09 MPa, the pre-curing temperature is 55 to 60°C, and the pre-curing time is 15 to 20 minutes.

6. The method for implanting FBG sensor electrodes using temperature-controlled graded curing and low-stress rolling as described in claim 1, characterized in that... In S4, the roll gap size is adjusted by 4~6µm each time.

7. The method for implanting FBG sensor electrodes using temperature-controlled graded curing and low-stress rolling as described in claim 1, characterized in that... In S5, the vacuum degree in the vacuum drying oven is -0.11 to -0.09 MPa, the final curing temperature is 65 to 70°C, and the final curing time is 25 to 30 minutes.

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