CN114964601B - A real-time monitoring device for pressure changes inside a battery - Google Patents

Abstract

The application belongs to the technical field related to lithium ion batteries, and discloses a real-time pressure change monitoring device for the interior of a battery, which comprises a working electrode, a counter electrode, a wire and a shell, wherein: the working electrode and the counter electrode are both made of materials with double electric layer effect, and the surfaces of the working electrode and the counter electrode are both in villus bulge structures; the casing is used for supporting the working electrode and the counter electrode and enabling the working electrode and the counter electrode to be arranged at intervals; the working electrode and the counter electrode are respectively connected with one conducting wire so as to lead out electric signals on the working electrode and the counter electrode. The application can respond to weak pressure change of mPa level and remarkably improve the detection sensitivity.

Description

A device for real-time monitoring of pressure changes inside a battery

Technical Field

The present invention belongs to the technical field related to battery internal pressure detection, and more specifically, relates to a device for real-time monitoring of pressure changes inside a battery.

Background technique

Lithium-ion batteries are the representative of modern high-performance batteries and are widely used in mobile phones, electric vehicles, power tools, digital cameras and other industries. In recent years, with the steady increase in the demand for lithium batteries from 3C products, the gradual expansion of the scale of the new energy vehicle market and the expansion of demand for energy storage batteries, the scale of lithium battery production has increased year by year. However, due to factors such as limited service life and irregular charging, lithium batteries may explode, seriously threatening the safety of users. Battery explosions are usually caused by the accumulation of a large amount of gas generated during the charging and discharging process of the battery, resulting in excessive internal pressure. Therefore, the safety of the battery can be monitored by monitoring the internal pressure of the battery to prevent explosions and other situations.

Although existing pressure sensors can be used in electrolyte environments, they are usually affected by factors such as complex structural design, large size, and lack of placement space inside the battery, which affects the use of the battery. For example, the method of reducing the positive and negative electrodes of the battery to provide space for the sensor increases the remaining volume of the battery, reduces the sites of ion reaction, and seriously affects the performance of the battery. Although reducing the volume of the sensor can only reduce the volume of the positive or negative electrode of the battery to reduce the impact of this method, the structural asymmetry may cause greater damage to the safety of the battery. The method of attaching the sensor to the positive and negative electrodes of the battery will reduce the performance of the battery on the one hand, and on the other hand, the formation of the SEI film will also have a serious impact on the performance of the sensor.

Chinese patent CN111524715 and Chinese patent CN109781335 disclose a pressure sensor that can be placed in an electrolyte. Although it can also be placed inside a battery, it is limited by the microstructure of its carbon nanotube film and can only respond to pressure changes above 10Pa. The detection accuracy is low and it cannot meet the needs of high-precision pressure detection inside the battery. Especially for situations such as dendrite precipitation inside the battery, the internal pressure change is often below 10Pa, and the above scheme cannot achieve detection. On the other hand, the carbon nanotubes in the above schemes can only respond to pressure in a single direction or at most two directions, whether they are arranged horizontally or vertically, while the pressure inside the battery comes from all directions, so it cannot be effectively detected.

Summary of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a real-time monitoring device for pressure changes inside a battery, which can respond to slight pressure changes at the mPa level and significantly improve the detection sensitivity.

To achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided a device for real-time monitoring of pressure changes inside a battery, the device comprising a working electrode, a counter electrode, a wire and a shell, wherein: the working electrode and the counter electrode are both made of materials having a double-layer effect, and the surfaces of the working electrode and the counter electrode are both velvety protrusion structures; the shell is used to support the working electrode and the counter electrode and arrange the working electrode and the counter electrode at intervals; the working electrode and the counter electrode are respectively connected to a wire to lead out the electrical signals on the working electrode and the counter electrode.

Preferably, the shell is made of polymer material.

Preferably, when the shell completely seals the working electrode and the counter electrode, the shell is made of a flexible polymer material.

Preferably, the material of the working electrode is a carbon material, and the material of the counter electrode is a carbon material or an inert metal.

Preferably, the material of the working electrode and the counter electrode is carbon nanotubes.

Preferably, the real-time monitoring device for pressure changes also includes a fixed structure, which includes a receiving cavity and a fixed part fixed on the receiving cavity, the working electrode and the counter electrode are arranged in the receiving cavity, and the shell is provided between the working electrode and the counter electrode and the receiving cavity, and the fixed part is fixed on the entity of the battery to be detected.

Preferably, the receiving cavity is a hollow cage structure.

Preferably, the fixing portion is connected to the side ear of the battery to be tested through an insulating coating; in a further preferred embodiment, the insulating coating is a polymer coating or a polymer modified coating.

Preferably, the villi-like protrusion structure is designed integrally with the working electrode or the counter electrode.

Preferably, the material of the fixing structure is aluminum or nickel.

In general, compared with the prior art, the above technical solution conceived by the present invention provides a device for real-time monitoring of pressure changes inside a battery, which has the following beneficial effects:

1. The surfaces of the working electrode and the counter electrode of the present application are both fuzzy protrusion structures and are made of materials with double-layer effect, which can make the pressure detection sensitivity reach the mPa level, significantly improving the sensitivity. In addition, the working electrode and the counter electrode can be directly applied to the interior of the battery. They are small in size, do not increase the remaining volume of the battery, and have no effect on the battery performance, making internal pressure detection of micro-batteries possible.

2. The working electrode and counter electrode of the present application having a velvety protrusion structure can respond to weak pressures in all directions inside the battery, thereby realizing the detection of weak pressure changes inside the battery.

3. The shell can completely cover the working electrode and the counter electrode or partially cover the working electrode and the counter electrode. There are no strict requirements for preparation, there is a lot of room for operation during preparation, and the structure is simple, so it has great prospects for industrial production and application.

4. The receiving cavity is a hollow cage structure, which allows the pressure inside the battery to act directly on the working electrode and the counter electrode through the hollow part, thereby achieving high-sensitivity pressure measurement.

5. The fixing part is connected to the side ear of the battery to be tested through an insulating coating, thereby avoiding the problem of short circuit caused by direct welding of the pressure change real-time monitoring device to the battery side ear, which affects the battery performance.

6. The villi protrusions of the present application are designed as an integrated whole with the working electrode and the counter electrode, and are part of the working electrode and the counter electrode, thus avoiding the electron transmission barrier formed by the gap and achieving more sensitive detection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a partial structural schematic diagram of a pressure change real-time monitoring device in the present application;

FIG2 is a schematic diagram of the villi protrusion structure on the surface of the working electrode or the counter electrode of the present application;

FIG3 is a schematic diagram of the structure of the pressure change real-time monitoring device in the present application;

FIG4 is a schematic diagram of the structure of the real-time pressure change monitoring device in the present application attached to the side ear of the battery to be tested;

FIG5 is a schematic diagram of the structure of the pressure change real-time monitoring device in the present application being placed at a non-ear portion of the battery;

FIG6 is a schematic diagram of the structure of the real-time pressure change monitoring device in the present application placed at the side ear of the battery;

FIG7 is a diagram showing the short-circuit current of a real-time monitoring device for internal pressure changes of a lithium battery as a function of pressure;

FIG8 is a graph showing the open circuit voltage of a real-time monitoring device for internal pressure changes of a lithium battery as a function of pressure;

FIG9 is a short-circuit current cycle performance diagram of a real-time monitoring device for internal pressure changes of a lithium battery;

FIG10 is an open circuit voltage cycle performance diagram of a real-time monitoring device for internal pressure changes of a lithium battery;

FIG11A is a schematic diagram of battery performance without the pressure change real-time monitoring device provided by the present application placed;

FIG11B is a schematic diagram of battery performance of a device for real-time monitoring of pressure changes as shown in Example 1 of the present application;

FIG11C is a schematic diagram of battery performance of a device for real-time monitoring of pressure changes as shown in Example 2 of the present application;

FIG. 12 is a schematic diagram showing a comparison of the short-circuit current detected by the real-time monitoring device for pressure changes of the present application and the real-time monitoring device for pressure changes of the prior art.

Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

100 - real-time monitoring device for pressure change; 110 - working electrode; 120 - counter electrode; 130 - wire; 140 - shell; 150 - fixed structure; 151 - receiving cavity; 152 - fixed part; 160 - insulating coating; 200 - lateral ear.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

Please refer to FIG. 1 . The present invention provides a device for real-time monitoring of pressure changes inside a battery. The device 100 for real-time monitoring of pressure changes includes a working electrode 110 , a counter electrode 120 , a wire 130 , and a shell 140 . The specific structure is as follows.

The working electrode 110 and the counter electrode 120 are both made of materials with double-layer effect, and the surfaces of the working electrode 110 and the counter electrode 120 are both fuzzy protrusion structures, as shown in Figure 2. In a further preferred solution, the fuzzy protrusion structure of the present application is designed as an integral whole with the working electrode or the counter electrode.

In a further preferred embodiment, the material of the working electrode 110 is a carbon material, and the material of the counter electrode 120 is a carbon material or an inert metal. Further preferably, the material of the working electrode 110 and the counter electrode 120 is carbon nanotubes.

The housing 140 is used to support the working electrode 110 and the counter electrode 120 and to allow the working electrode 110 and the counter electrode 120 to be spaced apart.

In a further preferred embodiment, the material of the housing 140 is a polymer material, such as modified polydimethylsiloxane, modified polyvinyl alcohol, etc. Further preferably, the material of the housing 140 is a flexible polymer material.

The shell 140 may partially cover the working electrode 110 and the counter electrode 120, or may completely cover the working electrode 110 and the counter electrode 120. When the shell 140 completely covers the working electrode 110 and the counter electrode 120, the shell 140 is a flexible polymer material, and its outer surface thickness is preferably 0.1mm-0.3mm.

The working electrode 110 and the counter electrode 120 are respectively connected to the wire 130 to lead out the electrical signals on the working electrode 110 and the counter electrode 120 .

In a further preferred embodiment, as shown in Fig. 3, the pressure change real-time monitoring device 100 further includes a fixing structure 150, and the fixing structure 150 includes a receiving cavity 151 and a fixing portion 152 fixed to the receiving cavity 151. The receiving cavity 151 is a hollow cage structure, for example, it can be a box structure with holes or a mesh structure.

The working electrode 110 and the counter electrode 120 are disposed in the receiving cavity 151 , and the shell 140 is disposed between the working electrode 110 and the counter electrode 120 and the receiving cavity 151 to avoid direct contact between the working electrode 110 and the counter electrode 120 and the receiving cavity 151 .

The fixing portion 152 is fixed to the body of the battery to be tested. The fixing portion 152 can be fixed to a suitable position on the body of the battery to be tested, or the fixing portion 152 can be led out through the body of the battery to be tested. In a further preferred embodiment, as shown in FIG4 , the fixing portion 152 is connected to the side ear 200 of the battery to be tested through an insulating coating 160. The insulating coating 160 is preferably a polymer coating or a polymer modified coating such as polyethylene, polyvinylidene fluoride, etc.

In a further preferred solution, the material of the fixing structure 150 is preferably aluminum or nickel.

This real-time monitoring device for pressure changes can detect internal mPa-level pressure through a material with a villi protrusion structure and a double-layer effect. When there is a slight pressure change, the villi can react quickly to achieve surface charge rearrangement, causing the working electrode and the counter electrode to produce a potential change, converting the internal pressure signal of the battery into an electrical signal, thereby achieving sensitive real-time detection of the internal pressure of the battery.

Example 1

In this embodiment, the working electrode 110, the counter electrode 120, the wire 130 and the support structure 140 are placed in the non-ear part of the battery through the fixing structure 150, as shown in FIG. 5 .

In this embodiment, the fixing portion 152 of the fixing structure 150 protrudes from the battery surface, the fixing structure 150 has a thickness of 0.8 mm and an area of 5 mm×30 mm; the receiving cavity 151 has a thickness of 0.5 mm and an area of 5 mm×5 mm. The material of the working electrode and the counter electrode is carbon black, with an area of 5 mm×5 mm and a thickness of 0.5 mm.

When the device is used to detect the internal pressure of the battery, the double-layer effect of the carbon black in the real-time monitoring device is used based on the pressure change, and the internal pressure change of the battery is converted into an electrical signal output, and then the internal pressure of the battery is calculated based on the relationship between the electrical signal and the pressure, and the safety state of the battery is further judged. In this embodiment, the battery to be detected is a lithium-ion battery, and its electrolyte is 1 mol/L LiPF6/EC:DEC (5:5). While monitoring the pressure in real time, it has no effect on the performance of the battery.

Example 2

In this embodiment, the working electrode 110, the counter electrode 120, the wire 130 and the support structure 140 are placed at the inner ear of the battery through the fixing structure 150, and attached to the side ear of the battery to be tested through the insulating coating, as shown in FIG6.

In this embodiment, the side ears of the battery to be tested have a thickness of 0.2 mm and an area of 2 mm×30 mm, the fixed structure for accommodating the real-time monitoring device for pressure changes has a thickness of 0.8 mm and an area of 2 mm×30 mm, the accommodating cavity has a thickness of 0.5 mm and an area of 2 mm×2 mm, the insulating coating is polyethylene, the working electrode and the counter electrode are carbon black carbon nanotubes with an area of 2 mm×2 mm and a thickness of 0.5 mm, and signal acquisition and signal transmission are realized through an electrochemical workstation.

When the device is used to detect the internal pressure of the battery, based on the double-layer effect of the carbon nanotube black of the working electrode and the counter electrode, the internal pressure change of the battery is converted into an electrical signal output, and then the internal pressure of the battery is calculated based on the relationship between the electrical signal and the pressure, and the safety state of the battery is further judged. In this embodiment, the battery to be detected is a lithium-ion battery, and its electrolyte is 1 mol/L LiPF6/EC:DEC (5:5). While monitoring the pressure in real time, it has no effect on the performance of the battery.

Of course, in other embodiments, the preparation method of the device for real-time monitoring of battery internal pressure changes can be modified according to actual needs.

Referring to FIG. 7 and FIG. 8 , it can be seen that when the measured pressure gradually increases within the range of 0 MPa to 2 MPa, the short-circuit current and open-circuit voltage measured in this embodiment gradually increase, and the short-circuit current and open-circuit voltage are linearly related to the pressure, and the linear fitting degrees are 0.9804 and 0.9918, respectively. This indicates that the short-circuit current and open-circuit voltage can be used as effective parameters to characterize pressure changes.

9 and 10 , it can be seen that after 700 pressure cycles, the short-circuit current and open-circuit voltage responses of the battery internal pressure change real-time monitoring device remain stable, indicating that the battery internal pressure change real-time monitoring device has excellent stability performance.

Referring to Figures 11A to 11C, it can be seen that the specific capacity of the lithium battery without the pressure detection provided by the present application is 146mAh/g, the specific capacity of the lithium battery in Example 1 is 143mAh/g, and the specific capacity of the lithium battery in Example 2 is 144mAh/g, which are 97.93% and 98.63% of the specific capacity of the lithium battery without the built-in pressure sensor provided by the present application, and have basically no effect on the battery performance. As shown in Figure 12, the real-time pressure change monitoring device provided by the present application generates an obvious response signal under the pressure of 190mPa, and the short-circuit current is 0.00043A/ ^m2 , and the sensitivity is significantly improved, while the solution in the prior art cannot respond to weak pressure changes.

In summary, the real-time pressure change monitoring device disclosed in the present application has a simpler structure, higher sensitivity, more flexible layout, and great application value.

It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims (9)

1. A pressure change real-time monitoring device for a battery interior, wherein the pressure change real-time monitoring device (100) comprises a working electrode (110), a counter electrode (120), a wire (130) and a housing (140), wherein:

The working electrode (110) and the counter electrode (120) are made of materials with double electric layer effects, the surfaces of the working electrode (110) and the counter electrode (120) are of villus bulge structures, and the villus bulge structures and the working electrode or the counter electrode are integrally designed; the housing (140) is used for supporting the working electrode (110) and the counter electrode (120) and enabling the working electrode (110) and the counter electrode (120) to be arranged at intervals; the working electrode (110) and the counter electrode (120) are respectively connected with a lead (130) so as to lead out electric signals on the working electrode (110) and the counter electrode (120);

The pressure change real-time monitoring device (100) further comprises a fixing structure (150), the fixing structure (150) comprises a containing cavity (151) and a fixing portion (152) fixed on the containing cavity (151), the working electrode (110) and the counter electrode (120) are arranged in the containing cavity (151), a shell (140) is arranged between the working electrode (110) and the counter electrode (120) and the containing cavity (151), and the fixing portion (152) is fixed on a body of a battery to be detected.

2. The device according to claim 1, wherein the housing (140) is made of a polymer material.

3. The pressure change real-time monitoring device according to claim 2, wherein the housing (140) is a flexible polymer material when the housing (140) completely seals the working electrode (110) and the counter electrode (120).

4. The pressure change real-time monitoring device according to claim 1, wherein the material of the working electrode (110) is a carbon material, and the material of the counter electrode (120) is a carbon material or an inert metal.

5. The pressure change real-time monitoring device according to claim 4, wherein the material of the working electrode (110) and the counter electrode (120) is carbon nanotubes.

6. The pressure change real-time monitoring device according to claim 5, wherein the accommodating cavity (151) is of a hollowed-out cage structure.

7. The pressure change real-time monitoring device according to claim 5, wherein the fixing portion (152) is connected to a side ear of the battery to be detected through an insulating coating (160).

8. The pressure change real-time monitoring device according to claim 7, wherein the insulating coating (160) is a polymer coating or a polymer modified coating.

9. The device for monitoring pressure changes in real time according to any one of claims 6 to 8, wherein the material of the fixing structure (150) is aluminum or nickel.