Graphene self-supporting membrane sensor and preparation method thereof

Abstract

The invention relates to the technical field of strain sensor preparation, in particular to a graphene self-supporting film sensor and a preparation method thereof. The invention discloses a graphene self-supporting membrane sensor which comprises a special particle layer for a graphene sensor, a special particle and elastomer base material mixing layer for the graphene sensor and an elastomer base material layer which are sequentially formed, the particle special for the graphene sensor comprises the following raw material components in parts by weight: 0.5-2 parts of graphene, 2-4 parts of carbon nanotubes, 3-8 parts of conductive carbon black, 5-10 parts of polytetrafluoroethylene and 76-89.5 parts of an elastomer base material, totaling 100 parts.

Description

Technical Field

[0001] This invention relates to the field of strain sensor fabrication technology, and in particular to a graphene self-supporting film sensor and its fabrication method. Background Technology With changes in the international energy landscape and advancements in battery technology, the global lithium battery industry is currently experiencing rapid growth. While lithium batteries bring convenience, their safety issues cannot be ignored. Countless lithium battery-related accidents occur globally each year, spanning energy storage, electric vehicles, and consumer electronics. Therefore, it is necessary to monitor the status of lithium battery cells in real time and address issues promptly to prevent accidents.

[0002] Thin-film sensors are core components in flexible electronics technology. They sense and measure strain and pressure by monitoring changes in electrical signals such as resistance, capacitance, or voltage caused by material deformation under stress. With the introduction of various battery safety policies, the application of thin-film sensors in the lithium battery industry will become increasingly widespread. However, the field of thin-film sensors still faces some challenges, such as how to maintain stable performance in complex environments (e.g., humidity, high and low temperatures), how to further reduce costs to achieve large-scale industrialization, and how to improve the integration and energy efficiency of sensor systems.

[0003] The core of thin-film sensors lies in the conductive sensing materials they use, primarily including metals such as copper and nickel, semiconductors such as silicon and germanium, and carbon materials such as graphene and carbon nanotubes. Among these, graphene possesses extremely high carrier mobility and excellent mechanical strength, and its resistance is highly sensitive to strain, enabling it to achieve extremely high sensitivity coefficients. Sensitivity can be further enhanced by designing microcrack or wrinkled structures. However, pure graphene materials lack elasticity and are easily damaged; furthermore, their high cost prevents them from meeting market demands.

[0004] Existing technologies have attempted to combine graphene with other metal materials to improve the sensitivity and applicability of sensors. For example, Chinese patent CN110487166A discloses a graphene-metal multilayer composite thin film sensor. However, metal-based sensors have the problem of low sensitivity, making it difficult to effectively monitor micro-deformations.

[0005] Chinese patent CN120992090A discloses a flexible thin-film sensor made of thermoplastic polyurethane (TPU). Through multi-dimensional structural design, it amplifies capacitance changes and improves sensitivity. However, the structure is complex, with a total of six layers of material and a relatively high overall thickness, making it difficult to meet the requirements for use in some small spaces.

[0006] The content of the background section is merely the technology known to the inventor and does not necessarily represent the prior art in this field. Summary of the Invention

[0007] In view of the above problems, the present invention discloses a graphene self-supporting film sensor, comprising, in sequence, a graphene sensor-specific particle layer, a graphene sensor-specific particle and elastomer substrate mixed layer, and an elastomer substrate layer; The raw material components of the graphene sensor-specific particles, by weight, total 100 parts, with the following proportions: 0.5-2 parts graphene, 2-4 parts carbon nanotubes, 3-8 parts conductive carbon black, 5-10 parts polytetrafluoroethylene (PTFE), and 76-89.5 parts elastomer substrate.

[0008] Furthermore, the graphene self-supporting film sensor has a thickness of 25-100 μm; and / or The elastomer substrate is one or more of the following: styrene-ethylene-butene-styrene block copolymer (SEBS), polyolefin elastomer (POE), thermoplastic polyurethane (TPU), ethylene propylene diene monomer (EPDM), and thermoplastic polyamide elastomer (TPEA); and / or The thickness of the graphene sensor-specific particle layer is 15%-35% of the total thickness, the thickness of the graphene sensor-specific particle and elastomer substrate hybrid layer is 15%-35% of the total thickness, and the thickness of the elastomer substrate layer is 30%-70% of the total thickness; and / or In the hybrid layer of graphene sensor-specific particles and elastomer substrate, the mass fraction of graphene sensor-specific particles is 30%-70%, and the mass fraction of elastomer substrate is 30%-70%; and / or The elastic modulus of the elastomer substrate is ≤10MPa; and / or The graphene has 3-5 layers and an ID / IG value of 0.8-1; and / or The carbon nanotubes are multi-walled carbon nanotubes; and / or The conductive carbon black is antistatic grade carbon black; and / or The PTFE is a protofibrillable PTFE powder.

[0009] Furthermore, the graphene self-supporting film sensor has a thickness of 50 μm; and / or 0.8-2 parts of the graphene; and / or 3-4 parts of the carbon nanotubes; and / or 5-8 parts of the conductive carbon black; and / or 7-10 parts of the polytetrafluoroethylene (PTFE); and / or 80-84 parts of the elastomer substrate; and / or The thickness of the graphene sensor-specific particle layer is 25% of the total thickness; the thickness of the graphene sensor-specific particle and elastomer substrate hybrid layer is 25% of the total thickness; and the thickness of the elastomer substrate layer is 50% of the total thickness; and / or In the hybrid layer of graphene sensor-specific particles and elastomer substrate, the mass fraction of graphene sensor-specific particles is 50%, and the mass fraction of elastomer substrate is 50%; and / or The elastic modulus of the elastomer substrate is 1-5 MPa.

[0010] Another aspect of the present invention discloses a method for preparing a graphene self-supporting film sensor, comprising the following steps: (1) Prepare graphene sensor-specific particles. The raw material components of the graphene sensor-specific particles are 100 parts by weight, and the proportions are as follows: graphene 0.5-2 parts, carbon nanotubes 2-4 parts, conductive carbon black 3-8 parts, polytetrafluoroethylene PTFE 5-10 parts, and elastomer substrate 76-89.5 parts. (2) Mix graphene sensor-specific particles with an elastomer substrate; (3) A three-layer co-extrusion casting composite film is formed, wherein the upper layer is a graphene sensor-specific particle layer, the middle layer is a mixture of graphene sensor-specific particles and elastomer substrate, and the lower layer is an elastomer substrate layer. (4) Press the composite membrane together to obtain a graphene self-supporting membrane sensor.

[0011] Furthermore, the elastomer substrate is one or more of styrene-ethylene-butene-styrene block copolymer (SEBS), polyolefin elastomer (POE), thermoplastic polyurethane (TPU), ethylene propylene diene monomer (EPDM), and thermoplastic polyamide elastomer (TPEA); and / or The elastic modulus of the elastomer substrate is ≤10MPa; and / or The thickness of the graphene sensor-specific particle layer is 15%-35% of the total thickness, the thickness of the graphene sensor-specific particle and elastomer substrate hybrid layer is 15%-35% of the total thickness, and the thickness of the elastomer substrate layer is 30%-70% of the total thickness; and / or In the hybrid layer of graphene sensor-specific particles and elastomer substrate, the mass fraction of graphene sensor-specific particles is 30%-70%, and the mass fraction of elastomer substrate is 30%-70%; and / or The graphene has 3-5 layers and an ID / IG value of 0.8-1; and / or The carbon nanotubes are multi-walled carbon nanotubes; and / or The conductive carbon black is antistatic grade carbon black; and / or The PTFE is a protofibrillable PTFE powder.

[0012] Furthermore, the graphene comprises 0.8-2 parts; and / or 3-4 parts of the carbon nanotubes; and / or 5-8 parts of the conductive carbon black; and / or 7-10 parts of the polytetrafluoroethylene (PTFE); and / or 80-84 parts of the elastomer substrate; and / or The thickness of the graphene sensor-specific particle layer is 25% of the total thickness; the thickness of the graphene sensor-specific particle and elastomer substrate hybrid layer is 25% of the total thickness; and the thickness of the elastomer substrate layer is 50% of the total thickness; and / or In the hybrid layer of graphene sensor-specific particles and elastomer substrate, the mass fraction of graphene sensor-specific particles is 50%, and the mass fraction of elastomer substrate is 50%; and / or The elastic modulus of the elastomer substrate is 1-5 MPa.

[0013] Furthermore, in step (1), the preparation process of graphene sensor-specific particles includes: (a) Weigh graphene, carbon nanotubes and conductive carbon black in proportion and stir to form mixture A; (b) Weigh the PTFE powder according to the proportion and mix it with mixture A to obtain mixture B; (c) After the mixture B is initially mixed with the elastomer substrate, it is melt-blended and extruded into granules to fibrillate the PTFE and distribute it evenly in the composite system to obtain graphene sensor-specific particles.

[0014] Furthermore, in step (a), a high-speed mixer is used for mixing at a speed of 2000-2500 r / min for a mixing time of 10-30 min; and / or In step (b), mixing is performed using a high-speed mixer at a speed of 1500-2000 r / min for a time of 10-20 min; and / or In step (c), the mixture is melt-blended and extruded into granules using a twin-screw extruder at a temperature of 150-180°C.

[0015] Furthermore, in step (3), a film is formed by three-layer co-extrusion casting using a casting machine, with a casting thickness of 40-120 μm; and / or In step (4), the rollers are pressed together by a double roller press. The roller press temperature is 90-120℃ and the roller press spacing is 25-100μm.

[0016] Furthermore, in step (2), the mixing method is low-speed mixing with a mixer speed of 150-200 r / min.

[0017] This invention effectively addresses the shortcomings of existing thin-film sensors on the market, meeting the requirements for long-term use, extremely high sensitivity, and adaptability to complex environments to meet the increasing market demand. To solve the above problems, this invention provides a graphene self-supporting film sensor for battery cell expansion detection and its preparation method. By using modified graphene as a conductive sensing material, and simultaneously compounding it with carbon black and carbon nanotubes to modify the elastomer for conductivity, and through process control, the accuracy and sensitivity of the sensor are greatly improved, enabling it to meet the needs of use in complex environments. The influence factor (GF: the ratio of resistance change rate to strain change rate) is increased from 3-5 for ordinary graphene materials to over 50. The service life far exceeds that of conventional metal-based thin-film sensors, reaching over 100,000 deformation cycles. Furthermore, the overall thickness of the sensor does not exceed 100μm, occupying minimal space and meeting the requirements for use in various confined environments. This invention meets the requirements for a graphene self-supporting film sensor for battery cell expansion detection.

[0018] This invention selects 3-5 layers of graphene with few defects, and forms a composite conductive network with carbon nanotubes and conductive carbon black. The graphene is sheet-like, the carbon nanotubes are strip-like, and the conductive carbon black is spherical. The three are combined to form an island-bridge structure, which can amplify the strain coefficient. The network structure is formed by PTFE fiberization, and the conductive network is completed. When the sensor is subjected to stress and deforms, the orientation effect can be suppressed, the fluctuation can be reduced, and the effect of stable strain monitoring can be achieved.

[0019] Furthermore, cell expansion mainly originates from volume changes in the main materials of the positive and negative electrodes. According to industry data, the expansion amount of a cell after 1000 cycles does not exceed 10% of the total (data source: CATL). For large-capacity cells such as power batteries, the expansion amount is relatively easy to monitor. However, for small cells such as consumer electronics cells, the expansion amount is often difficult to monitor. For example, the thickness of a 4000mAh mobile phone battery increases from 4.6mm to 5.0mm after 1000 cycles, with minimal deformation, which is difficult for conventional sensors to detect. Moreover, to maximize space utilization, the sensor needs to be as thin as possible, while the thickness of currently available thin-film sensors is generally above 180μm. The graphene self-supporting film sensor of this invention for cell expansion detection has a thickness of 25-100μm and can detect cell planar dimensional changes as small as 10μm, assisting in battery health assessment and ensuring equipment safety.

[0020] The main performance data of the graphene self-supporting film sensor obtained under the optimal scheme in this invention are as follows: thickness ≤50μm, minimum detectable strain 10μm, maximum strain change rate ≥30%, influence factor GF ≥110, operating temperature range -20-70℃, fatigue life ≥100,000 cycles, and service life ≥8 years.

[0021] The graphene self-supporting film sensor of this invention has excellent overall performance and offers significant advantages and application prospects compared to traditional thin-film sensors on the market. It also boasts advantages such as long service life, low manufacturing cost, and low equipment requirements. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a simplified flowchart for fabricating a graphene self-supporting film sensor; Figure 2 This is a graph showing the expansion results of the battery cell tested by the graphene self-supporting film sensor. Figure 3 It is the standard deviation of resistance after 20% strain has been stable for 24 hours at various temperatures. Detailed Implementation

[0023] In the following description, only certain exemplary embodiments are depicted simply. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0024] Unless otherwise defined herein, scientific and technical terms used in conjunction with this invention will have the meaning commonly understood by one of ordinary skill in the art. Furthermore, unless the context otherwise requires, singular terms shall include plural forms, and plural terms shall include singular forms. More specifically, as used in this specification and the appended claims, unless the context explicitly indicates otherwise, the singular forms “a,” “an,” and “the” include plural indicators. In this application, unless otherwise stated, the use of “or” means “and / or.” Furthermore, the use of the term “comprising” and other forms such as “including” and “containing” is not limiting. Moreover, the scope provided in the specification and the appended claims includes all values ​​between endpoints. Preferred embodiments of the invention are described below; it should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the invention.

[0025] This invention discloses a graphene self-supporting film sensor, which consists of three layers: the upper layer is 100% graphene sensor-specific particles (graphene sensor-specific particle layer), the middle layer is a mixture of graphene sensor-specific particles and elastomer substrate (graphene sensor-specific particle and elastomer substrate mixture layer), and the lower layer is 100% elastomer substrate (elastomer substrate layer).

[0026] A method for preparing a graphene self-supporting film sensor involves first preparing graphene sensor-specific particles. The raw material components, by weight, total 100 parts, with the following proportions: graphene 0.5-2 parts, e.g., 0.5, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, preferably 0.8-2; carbon nanotubes 2-4 parts, e.g., 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, preferably 3-4; conductive carbon black 3-8 parts, e.g., 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, preferably 5-8; polytetrafluoroethylene (PTFE) 5-1 parts. 0 parts, for example 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, preferably 7-10; 76-89.5 parts of elastomer substrate, for example 76, 80, 82, 84, 86, 88, 89.5, preferably 80-84; graphene has a sheet-like structure, carbon nanotubes have a long strip-like structure, and conductive carbon black has a spherical structure. The structures are different, and the structural changes that occur when the whole deformation occurs are greater, which plays a role in increasing the influence factor; PTFE is a stabilizer, which plays a role in extending fatigue life and service life; the elastomer substrate gives the whole body elasticity and is more sensitive to strain feedback, which plays a role in improving sensitivity.

[0027] Furthermore, the thickness of the graphene self-supporting film sensor is 25-100 μm, for example, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm; preferably, the thickness is 50 μm.

[0028] Furthermore, the elastomer substrate is at least one of styrene-ethylene-butene-styrene block copolymer (SEBS), polyolefin elastomer (POE), thermoplastic polyurethane (TPU), ethylene propylene diene monomer (EPDM), and thermoplastic polyamide elastomer (TPEA), with an elastic modulus ≤10MPa, such as 1MPa, 2MPa, 3MPa, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, or 10MPa. Preferably, the elastic modulus is 1-5MPa.

[0029] The definition of "elastic modulus" is: stress divided by strain in a uniaxial stress state.

[0030] Furthermore, the graphene has 3-5 layers, an ID / IG value of 0.8-1, the carbon nanotubes are multi-walled carbon nanotubes, and the conductive carbon black is antistatic grade carbon black. Furthermore, the PTFE is fibrillable PTFE powder.

[0031] According to another aspect of the present invention, a method for fabricating a graphene self-supporting film sensor is provided. A simplified flowchart of the fabrication process for the graphene self-supporting film sensor is shown below. Figure 1 .

[0032] The preparation method of graphene self-supporting film sensor includes: weighing graphene, carbon nanotubes and conductive carbon black in proportion, and stirring them in a high-speed mixer as mixture A. Preferably, the mixer speed is 2000-2500 r / min, such as 2000 r / min, 2100 r / min, 2200 r / min, 2300 r / min, 2400 r / min, 2500 r / min; the mixing time is 10-30 min, such as 10 min, 15 min, 20 min, 25 min, 30 min.

[0033] Weigh the PTFE powder and mix it with mixture A using a high-speed mixer to obtain mixture B. Preferably, the mixer speed is 1500-2000 r / min, such as 1500 r / min, 1600 r / min, 1700 r / min, 1800 r / min, 1900 r / min, or 2000 r / min; the mixing time is 10-20 min, such as 10 min, 12 min, 14 min, 16 min, 18 min, or 20 min.

[0034] After the mixture B is initially mixed with the elastomer substrate, it is melt-blended and extruded into granules by a twin-screw extruder to obtain graphene sensor-specific particles. Preferably, the extruder temperature is 150-180℃.

[0035] During the granulation process, PTFE is fibrillated. The fibrillated PTFE can form a fiber network in the material and be evenly distributed in the composite system, thereby improving the material's stability and service life.

[0036] Graphene sensor-specific particles are co-extruded into a film using a casting machine in three layers. The top layer consists of 100% graphene sensor-specific particles, with a thickness of 15%-35% of the total thickness, such as 15%, 20%, 25%, 30%, 35%, preferably 25%. The middle layer is a mixture of graphene sensor-specific particles and an elastomer substrate, with a thickness of 15%-35% of the total thickness, such as 15%, 20%, 25%, 30%, 35%, preferably 25%. The mixing method is a low-speed mixer, preferably with a mixer speed of 150 rpm. -200 r / min, for example 150 r / min, 160 r / min, 170 r / min, 180 r / min, 190 r / min, 200 r / min; mixing time is 10-20 min, for example 10 min, 12 min, 14 min, 16 min, 18 min, 20 min; the lower layer is 100% elastomer substrate, and the thickness is 30%-70% of the total thickness, for example 30%, 40%, 50%, 60%, 70%, preferably 50%, to obtain a multilayer composite film. Preferably, the thickness of the casting is 40-120μm; the upper layer is the sensing layer with a high content of conductive agent, but insufficient toughness. If it is too thin, it is easy to break; if it is too thick, the sensing sensitivity will decrease. The middle layer is the auxiliary sensing and transition layer with a lower concentration of conductive agent, which can amplify the resistance change and connect the upper and lower layers. If it is too thin, it will not be able to absorb the difference in elastic modulus between the upper and lower layers, which will cause tearing. If it is too thick, the sensing sensitivity will decrease. The lower layer is the toughening layer, which improves the overall toughness of the material and increases the maximum strain. If it is too thin, the overall toughness of the material will be insufficient, and the measurement range will be too low. If it is too thick, the strain of the lower layer may be too large and the strain of the upper layer may be too small, resulting in errors.

[0037] In the graphene sensor-specific particle and elastomer substrate hybrid layer, the mass fraction of the graphene sensor-specific particle is 30%-70%, for example 30%, 40%, 50%, 60%, 70%, preferably 50%; the mass fraction of the elastomer substrate is 30%-70%, for example 30%, 40%, 50%, 60%, 70%, preferably 50%.

[0038] The composite film is pressed by a two-roll press to control the thickness and eliminate the orientation effect generated during the casting process, thus obtaining a graphene self-supporting film sensor. Preferably, the roller press temperature is 90-120℃ and the roller press spacing is 25-100μm.

[0039] Orientation effects cause the conductive agent to align more uniformly and regularly along the casting direction, resulting in anisotropic conductivity. This means that the resistance value is lower in the casting direction and higher in other directions, causing errors and affecting measurement accuracy.

[0040] Example The invention generally described herein will be more readily understood by referring to the following examples, which are provided by way of illustration and are not intended to limit the invention. Furthermore, unless otherwise specified, the experimental methods in the following examples are conventional methods. Unless otherwise specified, the raw materials, reagents, and other materials used in the following examples are commercially available products.

[0041] The raw materials used in Examples 1-6 and Comparative Examples 1-3, except for graphene, were all commercially available. The graphene was SE1234 high-conductivity graphene produced by Changzhou Sixth Element Materials Technology Co., Ltd.

[0042] Battery cycle testing standard: GB / T 42260-2022 Strain gauge test standard: GB / T 12631-2017 Minimum strain detection limit test standard: GB / T 18806-2002 Fatigue life and service life testing standards: GB / T 13992-2010 Example 1 The graphene self-supporting film sensor of this embodiment consists of three layers: the upper layer is 100% graphene sensor-specific particles, the middle layer is a mixture of 50% graphene sensor-specific particles and 50% elastomer substrate, and the lower layer is 100% elastomer substrate. The thickness of the upper layer is 25% of the total thickness, the thickness of the middle layer is 25% of the total thickness, and the thickness of the lower layer is 50% of the total thickness. The graphene sensor-specific particles consist of 100 parts by weight, with the following proportions: graphene 0.5 parts, carbon nanotubes 2 parts, conductive carbon black 3 parts, PTFE 5 parts, and elastomer substrate 89.5 parts. The graphene self-supporting film sensor has a thickness of 25 μm. The elastomer substrate is SEBS with an elastic modulus of 10 MPa. The number of graphene layers is 3-5, the ID / IG value is 0.8, the carbon nanotubes are multi-walled carbon nanotubes, the conductive carbon black is antistatic grade carbon black, and the PTFE is fibrillable PTFE powder. The method for fabricating the graphene self-supporting film sensor in this embodiment includes: Weigh out graphene, carbon nanotubes, and conductive carbon black in proportion, and mix them in a high-speed mixer as mixture A. The mixer speed is 2000 r / min, and the mixing time is 30 min. Weigh the PTFE powder and mix it with mixture A using a high-speed mixer to obtain mixture B. The mixer speed is 1500 r / min and the mixing time is 20 min. After the mixture B is initially mixed with the elastomer substrate, it is melt-blended and extruded into granules through a twin-screw extruder to obtain graphene sensor-specific particles. The extruder temperature is 150℃. Graphene sensor-specific particles are co-extruded into a film using a casting machine in three layers. The upper layer consists of 100% graphene sensor-specific particles, the middle layer consists of 50% graphene sensor-specific particles mixed with 50% elastomer substrate, and the lower layer consists of 100% elastomer substrate. The thickness of the upper layer is 25% of the total thickness, the thickness of the middle layer is 25% of the total thickness, and the thickness of the lower layer is 50% of the total thickness, resulting in a multilayer composite film with a casting thickness of 40 μm. The composite film was pressed using a two-roll press to control its thickness and eliminate the orientation effect generated during the casting process, resulting in a graphene self-supporting film sensor. The roller press temperature was 90℃ and the roller press spacing was 25μm.

[0043] After welding wires to both ends of the obtained graphene self-supporting film sensor, the two ends of the sensor are connected with insulating glue to form a ring structure, which is then placed on the surface of the battery. After ensuring that the two are tightly attached, the battery is subjected to cycle testing, and the change in sensor resistance is monitored.

[0044] Example 2 The graphene self-supporting film sensor of this embodiment consists of three layers: the upper layer is 100% graphene sensor-specific particles, the middle layer is a mixture of 50% graphene sensor-specific particles and 50% elastomer substrate, and the lower layer is 100% elastomer substrate. The thickness of the upper layer is 25% of the total thickness, the thickness of the middle layer is 25% of the total thickness, and the thickness of the lower layer is 50% of the total thickness. The graphene sensor-specific particles consist of 100 parts by weight, with the following proportions: graphene 2 parts, carbon nanotubes 4 parts, conductive carbon black 8 parts, PTFE 10 parts, and elastomer substrate 76 parts. The graphene self-supporting film sensor has a thickness of 100 μm. The elastomer substrate is EPDM with an elastic modulus of 1 MPa. The number of graphene layers is 3-5, the ID / IG value is 1, the carbon nanotubes are multi-walled carbon nanotubes, the conductive carbon black is antistatic grade carbon black, and the PTFE is fibrillable PTFE powder. The method for fabricating the graphene self-supporting film sensor in this embodiment includes: Weigh out graphene, carbon nanotubes, and conductive carbon black in proportion, and mix them in a high-speed mixer as mixture A. The mixer speed is 2500 r / min, and the mixing time is 10 min. Weigh the PTFE powder and mix it with mixture A using a high-speed mixer to obtain mixture B. The mixer speed is 2000 r / min and the mixing time is 10 min. After the mixture B is initially mixed with the elastomer substrate, it is melt-blended and extruded into granules through a twin-screw extruder to obtain graphene sensor-specific particles. The extruder temperature is 180℃. Graphene sensor-specific particles are co-extruded into a film using a casting machine in three layers. The upper layer consists of 100% graphene sensor-specific particles, the middle layer consists of 50% graphene sensor-specific particles mixed with 50% elastomer substrate, and the lower layer consists of 100% elastomer substrate. The thickness of the upper layer is 25% of the total thickness, the thickness of the middle layer is 25% of the total thickness, and the thickness of the lower layer is 50% of the total thickness, resulting in a multilayer composite film with a casting thickness of 120 μm. The composite film was pressed using a two-roll press to control its thickness and eliminate the orientation effect generated during the casting process, resulting in a graphene self-supporting film sensor. The roller press temperature was 120℃ and the roller press spacing was 100μm.

[0045] After welding wires to both ends of the obtained graphene self-supporting film sensor, the two ends of the sensor are connected with insulating glue to form a ring structure, which is then placed on the surface of the battery. After ensuring that the two are tightly attached, the battery is subjected to cycle testing, and the change in sensor resistance is monitored.

[0046] Example 3 The graphene self-supporting film sensor of this embodiment consists of three layers: the upper layer is 100% graphene sensor-specific particles, the middle layer is a mixture of 50% graphene sensor-specific particles and 50% elastomer substrate, and the lower layer is 100% elastomer substrate. The thickness of the upper layer is 25% of the total thickness, the thickness of the middle layer is 25% of the total thickness, and the thickness of the lower layer is 50% of the total thickness. The graphene sensor-specific particles consist of 100 parts by weight, with the following proportions: graphene 1 part, carbon nanotubes 3 parts, conductive carbon black 5 parts, PTFE 7 parts, and elastomer substrate 84 parts. The graphene self-supporting film sensor has a thickness of 50 μm. The elastomer substrate is TPU with an elastic modulus of 3 MPa. The number of graphene layers is 3-5, the ID / IG value is 0.9, the carbon nanotubes are multi-walled carbon nanotubes, the conductive carbon black is antistatic grade carbon black, and the PTFE is fibrillable PTFE powder. The method for fabricating the graphene self-supporting film sensor in this embodiment includes: Weigh out graphene, carbon nanotubes, and conductive carbon black in proportion, and mix them in a high-speed mixer as mixture A. The mixer speed is 2300 r / min, and the mixing time is 20 min. Weigh the PTFE powder and mix it with mixture A using a high-speed mixer to obtain mixture B. The mixer speed is 1800 r / min and the mixing time is 15 min. After the mixture B is initially mixed with the elastomer substrate, it is melt-blended and extruded into granules through a twin-screw extruder to obtain graphene sensor-specific particles. The extruder temperature is 160℃. Graphene sensor-specific particles are co-extruded into a film using a casting machine in three layers. The upper layer consists of 100% graphene sensor-specific particles, the middle layer consists of 50% graphene sensor-specific particles mixed with 50% elastomer substrate, and the lower layer consists of 100% elastomer substrate. The thickness of the upper layer is 25% of the total thickness, the thickness of the middle layer is 25% of the total thickness, and the thickness of the lower layer is 50% of the total thickness, resulting in a multilayer composite film with a casting thickness of 60 μm. The composite film was pressed using a two-roll press to control its thickness and eliminate the orientation effect generated during the casting process, resulting in a graphene self-supporting film sensor. The roller press temperature was 100℃ and the roller press spacing was 50μm.

[0047] After welding wires to both ends of the obtained graphene self-supporting film sensor, the two ends of the sensor are connected with insulating glue to form a ring structure, which is then placed on the surface of the battery. After ensuring that the two are tightly attached, the battery is subjected to cycle testing, and the change in sensor resistance is monitored.

[0048] Example 4 The graphene self-supporting film sensor of this embodiment consists of three layers: the upper layer is 100% graphene sensor-specific particles, the middle layer is a mixture of 70% graphene sensor-specific particles and 30% elastomer substrate, and the lower layer is 100% elastomer substrate. The thickness of the upper layer is 15% of the total thickness, the thickness of the middle layer is 15% of the total thickness, and the thickness of the lower layer is 70% of the total thickness. The graphene sensor-specific particles consist of 100 parts by weight, with the following proportions: graphene 1.5 parts, carbon nanotubes 2.5 parts, conductive carbon black 7 parts, PTFE 8 parts, and elastomer substrate 82 parts. The graphene self-supporting film sensor has a thickness of 80 μm. The elastomer substrate is POE with an elastic modulus of 5 MPa. The number of graphene layers is 3-5, the ID / IG value is 0.85, the carbon nanotubes are multi-walled carbon nanotubes, the conductive carbon black is antistatic grade carbon black, and the PTFE is fibrillable PTFE powder. The method for fabricating the graphene self-supporting film sensor in this embodiment includes: Weigh out graphene, carbon nanotubes, and conductive carbon black in proportion, and mix them in a high-speed mixer as mixture A. The mixer speed is 2100 r / min, and the mixing time is 15 min. Weigh the PTFE powder and mix it with mixture A using a high-speed mixer to obtain mixture B. The mixer speed is 1600 r / min and the mixing time is 12 min. After the mixture B is initially mixed with the elastomer substrate, it is melt-blended and extruded into granules through a twin-screw extruder to obtain graphene sensor-specific particles. The extruder temperature is 170℃. Graphene sensor-specific particles are co-extruded into a film using a casting machine in three layers. The upper layer consists of 100% graphene sensor-specific particles, the middle layer consists of 50% graphene sensor-specific particles mixed with 50% elastomer substrate, and the lower layer consists of 100% elastomer substrate. The thickness of the upper layer is 15% of the total thickness, the thickness of the middle layer is 15% of the total thickness, and the thickness of the lower layer is 70% of the total thickness, resulting in a multilayer composite film with a casting thickness of 90 μm. The composite film was pressed using a two-roll press to control its thickness and eliminate the orientation effect generated during the casting process, resulting in a graphene self-supporting film sensor. The roller press temperature was 110℃ and the roller press spacing was 80μm.

[0049] After welding wires to both ends of the obtained graphene self-supporting film sensor, the two ends of the sensor are connected with insulating glue to form a ring structure, which is then placed on the surface of the battery. After ensuring that the two are tightly attached, the battery is subjected to cycle testing, and the change in sensor resistance is monitored.

[0050] Example 5 The graphene self-supporting film sensor of this embodiment consists of three layers: the upper layer is 100% graphene sensor-specific particles, the middle layer is a mixture of 30% graphene sensor-specific particles and 70% elastomer substrate, and the lower layer is 100% elastomer substrate. The thickness of the upper layer is 35% of the total thickness, the middle layer is 35% of the total thickness, and the lower layer is 30% of the total thickness. The graphene sensor-specific particles consist of 100 parts by weight, with the following proportions: graphene 0.8 parts, carbon nanotubes 3.5 parts, conductive carbon black 4 parts, PTFE 9 parts, and elastomer substrate 82.7 parts. The graphene self-supporting film sensor has a thickness of 40 μm. The elastomer substrate is TPEA with an elastic modulus of 8 MPa. The number of graphene layers is 3-5, the ID / IG value is 0.95, the carbon nanotubes are multi-walled carbon nanotubes, the conductive carbon black is antistatic grade carbon black, and the PTFE is fibrillable PTFE powder. The method for fabricating the graphene self-supporting film sensor in this embodiment includes: Weigh out graphene, carbon nanotubes, and conductive carbon black according to the proportions, and put them into a high-speed mixer to stir as mixture A. The mixer speed is 2200 r / min, and the mixing time is 25 min. Weigh the PTFE powder and mix it with mixture A using a high-speed mixer to obtain mixture B. The mixer speed is 1700 r / min and the mixing time is 16 min. After the mixture B is initially mixed with the elastomer substrate, it is melt-blended and extruded into granules through a twin-screw extruder to obtain graphene sensor-specific particles. The extruder temperature is 165℃. Graphene sensor-specific particles are co-extruded into a film using a casting machine in three layers. The upper layer is composed of 100% graphene sensor-specific particles, the middle layer is a mixture of 50% graphene sensor-specific particles and 50% elastomer substrate, and the lower layer is composed of 100% elastomer substrate, resulting in a multilayer composite film with a casting thickness of 50 μm. The composite film was pressed using a two-roll press to control its thickness and eliminate the orientation effect generated during the casting process, resulting in a graphene self-supporting film sensor. The roller press temperature was 95℃ and the roller press spacing was 40μm.

[0051] After welding wires to both ends of the obtained graphene self-supporting film sensor, the two ends of the sensor are connected with insulating glue to form a ring structure, which is then placed on the surface of the battery. After ensuring that the two are tightly attached, the battery is subjected to cycle testing, and the change in sensor resistance is monitored.

[0052] Example 6 The graphene self-supporting film sensor of this embodiment consists of three layers: the upper layer is 100% graphene sensor-specific particles, the middle layer is a mixture of 50% graphene sensor-specific particles and 50% elastomer substrate, and the lower layer is 100% elastomer substrate. The thickness of the upper layer is 25% of the total thickness, the thickness of the middle layer is 25% of the total thickness, and the thickness of the lower layer is 50% of the total thickness. The graphene sensor-specific particles consist of 100 parts by weight, with the following proportions: graphene 1.7 parts, carbon nanotubes 3.3 parts, conductive carbon black 6 parts, PTFE 6 parts, and elastomer substrate 83 parts. The graphene self-supporting film sensor has a thickness of 60 μm. The elastomer substrate is TPU with an elastic modulus of 6 MPa. The number of graphene layers is 3-5, the ID / IG value is 0.92, the carbon nanotubes are multi-walled carbon nanotubes, the conductive carbon black is antistatic grade carbon black, and the PTFE is fibrillable PTFE powder. The method for fabricating the graphene self-supporting film sensor in this embodiment includes: Weigh out graphene, carbon nanotubes, and conductive carbon black in proportion, and mix them in a high-speed mixer as mixture A. The mixer speed is 2250 r / min, and the mixing time is 18 min. Weigh the PTFE powder and mix it with mixture A using a high-speed mixer to obtain mixture B. The mixer speed is 1750 r / min and the mixing time is 14 min. After the mixture B is initially mixed with the elastomer substrate, it is melt-blended and extruded into granules through a twin-screw extruder to obtain graphene sensor-specific particles. The extruder temperature is 172℃. Graphene sensor-specific particles are co-extruded into a film using a casting machine in three layers. The upper layer consists of 100% graphene sensor-specific particles, the middle layer consists of 50% graphene sensor-specific particles mixed with 50% elastomer substrate, and the lower layer consists of 100% elastomer substrate. The thickness of the upper layer is 25% of the total thickness, the thickness of the middle layer is 25% of the total thickness, and the thickness of the lower layer is 50% of the total thickness, resulting in a multilayer composite film with a casting thickness of 70 μm. The composite film was pressed using a two-roll press to control its thickness and eliminate the orientation effect generated during the casting process, resulting in a graphene self-supporting film sensor. The roller press temperature was 105℃ and the roller press spacing was 60μm.

[0053] After welding wires to both ends of the obtained graphene self-supporting film sensor, the two ends of the sensor are connected with insulating glue to form a ring structure, which is then placed on the surface of the battery. After ensuring that the two are tightly attached, the battery is subjected to cycle testing, and the change in sensor resistance is monitored.

[0054] Comparative Example 1 (without graphene) This comparative example of a graphene self-supporting film sensor consists of three layers: the top layer is 100% sensor-specific particles, the middle layer is a mixture of 50% sensor-specific particles and 50% elastomer substrate, and the bottom layer is 100% elastomer substrate. The thickness of the top layer is 25% of the total thickness, the middle layer is 25% of the total thickness, and the bottom layer is 50% of the total thickness. The sensor-specific particles, by weight, comprise 100 parts in total, with the following proportions: 3 parts carbon nanotubes, 5 parts conductive carbon black, 7 parts PTFE, and 85 parts elastomer substrate. The film sensor thickness is 50 μm. The elastomer substrate is TPU with an elastic modulus of 3 MPa. The carbon nanotubes are multi-walled carbon nanotubes, the conductive carbon black is antistatic grade carbon black, and the PTFE is fibrillable PTFE powder. The fabrication method of the thin-film sensor in this comparative example includes: Weigh carbon nanotubes and conductive carbon black according to the proportion, and stir them in a high-speed mixer as mixture A. The mixer speed is 2300 r / min and the mixing time is 20 min. Weigh the PTFE powder and mix it with mixture A using a high-speed mixer to obtain mixture B. The mixer speed is 1800 r / min and the mixing time is 15 min. After the mixture B is initially mixed with the elastomer substrate, it is melt-blended and extruded into granules through a twin-screw extruder to obtain sensor-specific particles. The extruder temperature is 160℃. Sensor-specific particles are co-extruded into a film using a casting machine in three layers. The upper layer is composed of 100% sensor-specific particles, the middle layer is a mixture of 50% sensor-specific particles and 50% elastomer substrate, and the lower layer is composed of 100% elastomer substrate. The thickness of the upper layer is 25% of the total thickness, the thickness of the middle layer is 25% of the total thickness, and the thickness of the lower layer is 50% of the total thickness, resulting in a multilayer composite film with a casting thickness of 60 μm. The composite film is pressed by a two-roll press to control the thickness and eliminate the orientation effect generated during the casting process, thus obtaining a thin film sensor. The temperature of the roll press is 100℃ and the distance between the roll presses is 50μm.

[0055] After welding wires to both ends of the obtained thin-film sensor, the two ends of the sensor are connected with insulating glue to form a ring structure, which is then placed on the surface of the battery. After ensuring that the two are in close contact, the battery is subjected to cycle testing, and the change in sensor resistance is monitored.

[0056] Comparative Example 2 (Graphene outside the index range) This comparative example of a graphene self-supporting film sensor consists of three layers: the top layer is 100% graphene sensor-specific particles, the middle layer is a mixture of 50% graphene sensor-specific particles and 50% elastomer substrate, and the bottom layer is 100% elastomer substrate. The thickness of the top layer is 25% of the total thickness, the middle layer is 25% of the total thickness, and the bottom layer is 50% of the total thickness. The graphene sensor-specific particles, by weight, comprise 100 parts in total, with the following proportions: graphene 1 part, carbon nanotubes 3 parts, conductive carbon black 5 parts, PTFE 7 parts, and elastomer substrate 84 parts. The graphene self-supporting film sensor has a thickness of 50 μm. The elastomer substrate is TPU with an elastic modulus of 3 MPa. The number of graphene layers is 1-2, with an ID / IG value of 1.5. The carbon nanotubes are multi-walled carbon nanotubes, the conductive carbon black is antistatic grade carbon black, and the PTFE is fibrillable PTFE powder. The fabrication method of the graphene self-supporting film sensor in this comparative example includes: Weigh out graphene, carbon nanotubes, and conductive carbon black in proportion, and mix them in a high-speed mixer as mixture A. The mixer speed is 2300 r / min, and the mixing time is 20 min. Weigh the PTFE powder and mix it with mixture A using a high-speed mixer to obtain mixture B. The mixer speed is 1800 r / min and the mixing time is 15 min. After the mixture B is initially mixed with the elastomer substrate, it is melt-blended and extruded into granules through a twin-screw extruder to obtain graphene sensor-specific particles. The extruder temperature is 160℃. Graphene sensor-specific particles are co-extruded into a film using a casting machine in three layers. The upper layer consists of 100% graphene sensor-specific particles, the middle layer consists of 50% graphene sensor-specific particles mixed with 50% elastomer substrate, and the lower layer consists of 100% elastomer substrate. The thickness of the upper layer is 25% of the total thickness, the thickness of the middle layer is 25% of the total thickness, and the thickness of the lower layer is 50% of the total thickness, resulting in a multilayer composite film with a casting thickness of 60 μm. The composite film was pressed using a two-roll press to control its thickness and eliminate the orientation effect generated during the casting process, resulting in a graphene self-supporting film sensor. The roller press temperature was 100℃ and the roller press spacing was 50μm.

[0057] After welding wires to both ends of the obtained graphene self-supporting film sensor, the two ends of the sensor are connected with insulating glue to form a ring structure, which is then placed on the surface of the battery. After ensuring that the two are tightly attached, the battery is subjected to cycle testing, and the change in sensor resistance is monitored.

[0058] Comparative Example 3 (without using the three-layer co-extrusion process) The graphene self-supporting film sensor of this comparative example has a total of 100 parts by weight of each raw material component, with the following proportions: 1 part graphene, 3 parts carbon nanotubes, 5 parts conductive carbon black, 7 parts PTFE, and 84 parts elastomer substrate. The graphene self-supporting film sensor has a thickness of 50 μm, the elastomer substrate is TPU with an elastic modulus of 3 MPa, the number of graphene layers is 3-5, the ID / IG value is 0.9, the carbon nanotubes are multi-walled carbon nanotubes, the conductive carbon black is antistatic grade carbon black, and the PTFE is fibrillable PTFE powder. The fabrication method of the graphene self-supporting film sensor in this comparative example includes: Weigh out graphene, carbon nanotubes, and conductive carbon black in proportion, and mix them in a high-speed mixer as mixture A. The mixer speed is 2300 r / min, and the mixing time is 20 min. Weigh the PTFE powder and mix it with mixture A using a high-speed mixer to obtain mixture B. The mixer speed is 1800 r / min and the mixing time is 15 min. After the mixture B is initially mixed with the elastomer substrate, it is melt-blended and extruded into granules through a twin-screw extruder to obtain graphene sensor-specific particles. The extruder temperature is 160℃. Graphene sensor-specific particles were cast into a film using a casting machine, with a casting thickness of 60 μm. The cast film is pressed by a two-roll press to control the thickness and eliminate the orientation effect generated during the casting process, thus obtaining a graphene self-supporting film sensor. The temperature of the roll press is 100℃ and the distance between the roll presses is 50μm. After welding wires to both ends of the obtained graphene self-supporting film sensor, the two ends of the sensor are connected with insulating glue to form a ring structure, which is then placed on the surface of the battery. After ensuring that the two are tightly attached, the battery is subjected to cycle testing, and the change in sensor resistance is monitored.

[0059] Test results are available Figures 2-3 Table 1-2 shows that all values ​​are averages obtained from testing three samples from the same batch.

[0060] Table 1 Minimum Detection Limit Test

[0061] Table 2 Influencing Factors, Fatigue Life, and Service Life

[0062] Test results show that the graphene self-supporting mold sensor prepared in this invention has excellent micro-strain detection performance, with a minimum detectable strain of 10 μm, a maximum influence factor GF of ≥110, a fatigue life of ≥100,000 cycles, a maximum service life of ≥8 years, and a resistance drift of ≤10% after standing for 24 hours with a strain of 20% in the range of -20-70℃, which meets the requirements for cell expansion detection.

[0063] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention. Furthermore, although the elements of the present invention can be described or claimed individually, it is also conceivable to have multiple elements, unless explicitly limited to a single element.

Claims

1. A graphene self-supporting film sensor, characterized in that, It includes, in sequence, a graphene sensor-specific particle layer, a graphene sensor-specific particle and elastomer substrate hybrid layer, and an elastomer substrate layer; The raw material components of the graphene sensor-specific particles, by weight, total 100 parts, with the following proportions: graphene 0.5-2 parts, carbon nanotubes 2-4 parts, conductive carbon black 3-8 parts, polytetrafluoroethylene 5-10 parts, and elastomer substrate 76-89.5 parts.

2. The graphene self-supporting film sensor according to claim 1, characterized in that, The graphene self-supporting film sensor has a thickness of 25-100 μm; and / or The elastomer substrate is one or more of the following: styrene-ethylene-butene-styrene block copolymer (SEBS), polyolefin elastomer (POE), thermoplastic polyurethane (TPU), ethylene propylene diene monomer (EPDM), and thermoplastic polyamide elastomer (TPEA); and / or The thickness of the graphene sensor-specific particle layer is 15%-35% of the total thickness, the thickness of the graphene sensor-specific particle and elastomer substrate hybrid layer is 15%-35% of the total thickness, and the thickness of the elastomer substrate layer is 30%-70% of the total thickness; and / or In the hybrid layer of graphene sensor-specific particles and elastomer substrate, the mass fraction of graphene sensor-specific particles is 30%-70%, and the mass fraction of elastomer substrate is 30%-70%; and / or The elastic modulus of the elastomer substrate is ≤10MPa; and / or The graphene has 3-5 layers and an ID / IG value of 0.8-1; and / or The carbon nanotubes are multi-walled carbon nanotubes; and / or The conductive carbon black is antistatic grade carbon black; and / or The polytetrafluoroethylene is a protofibroblastable polytetrafluoroethylene powder.

3. The graphene self-supporting film sensor according to claim 2, characterized in that, The graphene self-supporting film sensor has a thickness of 50 μm; and / or 0.8-2 parts of the graphene; and / or 3-4 parts of the carbon nanotubes; and / or 5-8 parts of the conductive carbon black; and / or 7-10 parts of the polytetrafluoroethylene; and / or 80-84 parts of the elastomer substrate; and / or The thickness of the graphene sensor-specific particle layer is 25% of the total thickness; the thickness of the graphene sensor-specific particle and elastomer substrate hybrid layer is 25% of the total thickness; and the thickness of the elastomer substrate layer is 50% of the total thickness; and / or In the hybrid layer of graphene sensor-specific particles and elastomer substrate, the mass fraction of graphene sensor-specific particles is 50%, and the mass fraction of elastomer substrate is 50%; and / or The elastic modulus of the elastomer substrate is 1-5 MPa.

4. A method for fabricating a graphene self-supporting film sensor, characterized in that, Includes the following steps: (1) Prepare graphene sensor-specific particles. The graphene sensor-specific particles are composed of 100 parts by weight, and the proportions are as follows: graphene 0.5-2 parts, carbon nanotubes 2-4 parts, conductive carbon black 3-8 parts, polytetrafluoroethylene 5-10 parts, and elastomer substrate 76-89.5 parts. (2) Mix graphene sensor-specific particles with an elastomer substrate; (3) A three-layer co-extrusion casting composite film is formed, wherein the upper layer is a graphene sensor-specific particle layer, the middle layer is a mixture of graphene sensor-specific particles and elastomer substrate, and the lower layer is an elastomer substrate layer. (4) Press the composite membrane together to obtain a graphene self-supporting membrane sensor.

5. The method for preparing a graphene self-supporting film sensor according to claim 4, characterized in that, The elastomer substrate is one or more of the following: styrene-ethylene-butene-styrene block copolymer (SEBS), polyolefin elastomer (POE), thermoplastic polyurethane (TPU), ethylene propylene diene monomer (EPDM), and thermoplastic polyamide elastomer (TPEA); and / or The elastic modulus of the elastomer substrate is ≤10MPa; and / or The thickness of the graphene sensor-specific particle layer is 15%-35% of the total thickness, the thickness of the graphene sensor-specific particle and elastomer substrate hybrid layer is 15%-35% of the total thickness, and the thickness of the elastomer substrate layer is 30%-70% of the total thickness; and / or In the hybrid layer of graphene sensor-specific particles and elastomer substrate, the mass fraction of graphene sensor-specific particles is 30%-70%, and the mass fraction of elastomer substrate is 30%-70%; and / or The graphene has 3-5 layers and an ID / IG value of 0.8-1; and / or The carbon nanotubes are multi-walled carbon nanotubes; and / or The conductive carbon black is antistatic grade carbon black; and / or The polytetrafluoroethylene is a protofibroblastable polytetrafluoroethylene powder.

6. The method for preparing a graphene self-supporting film sensor according to claim 4, characterized in that, 0.8-2 parts of the graphene; and / or 3-4 parts of the carbon nanotubes; and / or 5-8 parts of the conductive carbon black; and / or 7-10 parts of the polytetrafluoroethylene; and / or 80-84 parts of the elastomer substrate; and / or The thickness of the graphene sensor-specific particle layer is 25% of the total thickness; the thickness of the graphene sensor-specific particle and elastomer substrate hybrid layer is 25% of the total thickness; and the thickness of the elastomer substrate layer is 50% of the total thickness; and / or In the hybrid layer of graphene sensor-specific particles and elastomer substrate, the mass fraction of graphene sensor-specific particles is 50%, and the mass fraction of elastomer substrate is 50%; and / or The elastic modulus of the elastomer substrate is 1-5 MPa.

7. The method for preparing a graphene self-supporting film sensor according to claim 4, characterized in that, In step (1), the preparation process of graphene sensor-specific particles includes: (a) Weigh graphene, carbon nanotubes and conductive carbon black in proportion and stir to form mixture A; (b) Weigh the polytetrafluoroethylene powder according to the proportion and mix it with mixture A to obtain mixture B; (c) After the mixture B is initially mixed with the elastomer substrate, it is melt-blended, extruded and granulated to obtain graphene sensor-specific particles.

8. The method for preparing a graphene self-supporting film sensor according to claim 7, characterized in that, In step (a), a high-speed mixer is used for mixing at a speed of 2000-2500 r / min for a mixing time of 10-30 min; and / or In step (b), mixing is performed using a high-speed mixer at a speed of 1500-2000 r / min for a time of 10-20 min; and / or In step (c), the mixture is melt-blended and extruded into granules using a twin-screw extruder at a temperature of 150-180°C.

9. The method for preparing a graphene self-supporting film sensor according to claim 4, characterized in that, In step (3), a film is formed by three-layer co-extrusion casting using a casting machine, with a casting thickness of 40-120 μm; and / or In step (4), the rollers are pressed together by a double roller press. The roller press temperature is 90-120℃ and the roller press spacing is 25-100μm.

10. The method for preparing a graphene self-supporting film sensor according to claim 4, characterized in that, In step (2), the mixing method is low-speed mixing machine, and the mixer speed is 150-200r / min.

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