Flexible sensor for lithium battery electrolyte leakage detection and preparation method thereof

Abstract

The application discloses a flexible sensor for lithium battery electrolyte leakage detection and a preparation method thereof. The flexible sensor is composed of a polyethylene layer and an oxidized graphene layer. The oxidized graphene layer is formed by drying and stacking an oxidized graphene aqueous dispersion on a polyethylene film. When stimulated by electrolyte solution volatilized from a leaking lithium battery, the flexible sensor is bent and deformed. The prepared flexible sensor has obvious deformation, an intuitive sensing method, fast response speed and simple preparation method, and provides a feasible idea for designing and preparing the flexible sensor for lithium battery electrolyte leakage detection.

Description

Technical Field

[0001] This invention relates to a flexible sensor, and more particularly to a flexible sensor for detecting electrolyte leakage in lithium batteries and its preparation method. Background Technology

[0002] Lithium-ion batteries, as an ideal energy storage system, are widely used in our daily lives. However, as a power source that converts chemical energy into electrical energy, the safety of lithium-ion batteries under conditions of heating, compression, impact, or overcharging has attracted deep concern from consumers. Lithium-ion battery failure is often accompanied by electrolyte leakage, and most safety issues are usually caused by the deflagration or explosion of organic vapors generated by electrolyte leakage. Lithium-ion battery electrolytes are mainly composed of solvents such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), or diethyl carbonate (DEC). These solvents are volatile and redox neutral, making them difficult to detect. Therefore, developing a rapid and effective method for early detection of lithium-ion battery electrolyte leakage is crucial for providing safety assurance in the widespread application of lithium-ion batteries. Summary of the Invention

[0003] The problem this invention aims to solve is that existing lithium battery electrolyte leakage detection sensors have complex fabrication processes and high costs. This invention proposes a lithium battery electrolyte leakage detection sensor with a simple fabrication process, low cost, low detection limit, and rapid detection capability. The fabricated sensor can respond to diethyl carbonate concentrations as low as 0.66 ppm.

[0004] To achieve the objectives of this invention, the following technical solution is provided: I. A flexible sensor for detecting electrolyte leakage in lithium batteries The flexible sensor comprises a polyethylene layer and a graphene oxide layer, which are stacked together.

[0005] When the flexible sensor comes into contact with the electrolyte solution volatilized from the lithium battery, the flexible sensor bends and deforms, specifically bending from one side of the polyethylene layer to the side of the graphene oxide layer.

[0006] The electrolyte solution emitted by the lithium battery includes dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate.

[0007] II. A method for fabricating a flexible sensor for detecting electrolyte leakage in lithium batteries. The preparation method includes the following steps: 1) Lay the polyethylene film flat on the glass plate; 2) Fix the polyethylene film around its perimeter and form a groove on the upper surface of the polyethylene film; 3) The graphene oxide dispersion is evenly coated in the groove and then dried until the water in the graphene oxide dispersion evaporates to form a graphene oxide-polyethylene composite film. 4) After cutting the graphene oxide-polyethylene composite film into the target shape, a flexible sensor (1) is obtained.

[0008] In step 3), the concentration of the graphene oxide dispersion is 2 mg / ml.

[0009] The drying temperature is 40°C.

[0010] As the concentration of the electrolyte solution decreases, the flexible sensor recovers its original shape. The sensor exhibits excellent linearity in the detection of diethyl carbonate. The detection limit for diethyl carbonate reaches 0.66 ppm. This sensor can effectively detect lithium battery leakage in sealed containers.

[0011] The angle between the cutting direction of the graphene oxide-polyethylene composite film and the direction of the molecular chains in the polyethylene layer is denoted as the cutting angle; changing the cutting angle adjusts the deformation mode of the flexible sensor, thereby achieving deformation control of the flexible sensor.

[0012] When the cutting angle is 0°, the prepared flexible sensor bends along the short side under the stimulation of the electrolyte solution; when the cutting angle is 90°, the prepared flexible sensor bends along the long side under the stimulation of the electrolyte solution; when the cutting angle is between 0° and 90° or between 90° and 180°, the prepared flexible sensor undergoes helical deformation under the stimulation of the electrolyte solution.

[0013] The principle of the flexible sensor for detecting electrolyte leakage in lithium batteries described in this invention is as follows: Solvent components in the leaked lithium battery electrolyte, such as dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate, evaporate and enter the polyethylene layer of the flexible sensor, causing the polyethylene layer to swell. This leads to stress mismatch at the interface between the polyethylene layer and the graphene oxide layer of the flexible sensor, resulting in bending and deformation of the sensor. This causes a noticeable shape change in the sensor.

[0014] The beneficial effects of this invention are as follows: 1. The method for preparing a flexible sensor for detecting electrolyte leakage in lithium batteries, as described in this invention, is simple to operate, easy to implement, and suitable for mass production.

[0015] 2. The flexible sensor prepared by this invention for detecting electrolyte leakage in lithium batteries has a fast response speed, obvious deformation, reversible and repeatable deformation process, and low detection limit. Attached Figure Description

[0016] To more clearly illustrate the purpose, technical solution, and beneficial effects of this invention, the following figures are provided for illustrative purposes: Figure 1 This is a schematic diagram showing the deformation of a flexible sensor for detecting lithium battery electrolyte leakage under the stimulation of lithium battery electrolyte.

[0017] Figure 2 This is a cross-sectional scanning electron microscope image of a flexible sensor for detecting electrolyte leakage in lithium batteries according to the present invention.

[0018] Figure 3 The sensor's response rate to different amounts of DEC is measured in a 750ml sealed container.

[0019] Figure 4 The sensor's response rate to 0.5 μl DEC in a 750 ml sealed container.

[0020] Figure 5 This represents the real-time response rate of the sensor to the lithium battery electrolyte.

[0021] In the diagram: 1-Flexible sensor, 2-Polyethylene layer, 3-Graphene oxide layer. Detailed Implementation

[0022] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments: like Figure 1 As shown, the flexible sensor 1 includes a flexible polyethylene layer 2 and a graphene oxide layer 3, which are stacked together, with the graphene oxide layer 3 closely attached to the polyethylene layer 2.

[0023] When the flexible sensor comes into contact with the electrolyte solution volatilized from the lithium battery, the polyethylene layer swells, while the graphene oxide layer does not undergo significant shape change or bending. This causes the flexible sensor to bend and deform, specifically bending from one side of the polyethylene layer 2 towards the side of the graphene oxide layer 3.

[0024] The electrolyte solution emitted by lithium batteries includes dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), or diethyl carbonate (DEC).

[0025] As the concentration of the electrolyte solution decreases, the flexible sensor recovers its deformation. The sensor exhibits excellent linearity in the detection of diethyl carbonate. The detection limit for diethyl carbonate reaches 0.66 ppm. The sensor can effectively detect lithium battery leakage in sealed containers.

[0026] like Figure 2 The image shown is a scanning electron microscope image of the flexible sensor prepared in this embodiment, from which it can be clearly seen that the flexible sensor has a double-layer structure.

[0027] A method for fabricating a flexible sensor for detecting electrolyte leakage in lithium batteries, the method comprising the following steps: 1) Lay a 10×12mm polyethylene film flat on the glass plate; 2) Use multi-layer polyimide tape to fix the polyethylene film around its perimeter and form a groove with a depth of 0.5 mm on the upper surface of the polyethylene film; 3) After taking 8 ml of graphene oxide dispersion with a pipette, evenly drop the graphene oxide dispersion into the groove, and then dry it until the water in the graphene oxide dispersion evaporates to form a graphene oxide-polyethylene composite film; wherein, the concentration of graphene oxide dispersion is 2 mg / ml; and the drying temperature is 40℃.

[0028] 4) After cutting the graphene oxide-polyethylene composite film into the target shape, the flexible sensor 1 is obtained.

[0029] The angle between the cutting direction of the graphene oxide-polyethylene composite film and the direction of the molecular chains in the polyethylene layer 2 is denoted as the cutting angle; changing the cutting angle adjusts the deformation mode of the flexible sensor, thereby achieving deformation control of the flexible sensor.

[0030] When the cutting angle is 0°, the prepared flexible sensor 1 bends along the short side under the stimulation of the electrolyte solution; when the cutting angle is 90°, the prepared flexible sensor 1 bends along the long side under the stimulation of the electrolyte solution; when the cutting angle is between 0° and 90° or between 90° and 180°, the prepared flexible sensor 1 undergoes helical deformation under the stimulation of the electrolyte solution.

[0031] The performance of the flexible sensor used for detecting electrolyte leakage in lithium batteries will be described in detail below through specific embodiments.

[0032] like Figure 1 As shown, the initial width of the circular sensor in the air is defined as... L 0 The width of the sensor when exposed to diethyl carbonate vapor is L t Define the sensor's response rate. R The degree of sensor response to diethyl carbonate is defined as: R =( L 0 - L t ) / L 0 ×100%.

[0033] The sensor was placed in a 0.75 L sealed chamber, and 0.5 ~ 15 μL of diethyl carbonate liquid was added sequentially. Figure 3The response-time curves show that when 0.5, 1, 5, 10, and 15 μL of diethyl carbonate were injected, the response rates reached 8.99%, 13.89%, 34.50%, 57.03%, and 72.50%, respectively. The shape change became more pronounced with increasing DEC addition.

[0034] A flexible sensor for detecting electrolyte leakage in lithium-ion batteries exhibits a low detection limit. Adding 0.5 μL of diethyl carbonate to a 0.75 L sealed cavity, such as... Figure 4 As shown, the sensor's response rate is 9%. The detection limit for diethyl carbonate is as low as 0.66 ppm.

[0035] The effectiveness of the sensor is demonstrated below using the sensing of a real lithium battery leak as an example.

[0036] After placing the sensor in a sealed chamber for 2 minutes, a damaged lithium battery was inserted, and the sensor's status was monitored in real time. Figure 5 As shown, the sensor's response rate increased significantly immediately after the leak, proving the feasibility of using this sensor for lithium battery leak detection.

[0037] Finally, it should be noted that the above embodiments and descriptions are only used to illustrate the technical solutions of the present invention and not to limit it. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the disclosure of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the protection scope of the claims of the present invention.

Claims

1. A flexible sensor for lithium battery electrolyte leakage detection, characterized in that, The flexible sensor (1) is a double-layer structure composed of a polyethylene layer (2) and a graphene oxide layer (3), with the graphene oxide layer (3) closely attached to the polyethylene layer (2). When the flexible sensor comes into contact with the electrolyte solution volatilized from the lithium battery, the flexible sensor bends and deforms, specifically bending from one side of the polyethylene layer (2) to the side of the graphene oxide layer (3). The electrolyte solution emitted by the lithium battery includes dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate.

2. The method for fabricating a flexible sensor for detecting electrolyte leakage in lithium batteries according to claim 1, characterized in that, The preparation method includes the following steps: 1) Lay the polyethylene film flat on the glass plate; 2) Fix the polyethylene film around its perimeter and form a groove on the upper surface of the polyethylene film; 3) The graphene oxide dispersion is evenly coated in the groove and then dried until the water in the graphene oxide dispersion evaporates to form a graphene oxide-polyethylene composite film. 4) After cutting the graphene oxide-polyethylene composite film into the target shape, a flexible sensor (1) is obtained.

3. The method for fabricating a flexible sensor for detecting electrolyte leakage in lithium batteries according to claim 2, characterized in that, In step 3), the concentration of the graphene oxide dispersion is 2 mg / ml.

4. The method for fabricating a flexible sensor for detecting electrolyte leakage in lithium batteries according to claim 2, characterized in that, The drying temperature is 40°C.

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