WO2021121032A1

WO2021121032A1 - Positive electrode bus structure for battery capable of generating graphene by means of friction, current collector, and battery

Info

Publication number: WO2021121032A1
Application number: PCT/CN2020/133173
Authority: WO
Inventors: 陈璞; 刘正军; 罗云峰; 罗小松; 李成钢
Original assignee: 瑞海泊有限公司
Priority date: 2019-12-18
Filing date: 2020-12-01
Publication date: 2021-06-24
Also published as: CN111129415B; CN111129415A

Abstract

Provided are a positive electrode bus structure for a battery capable of generating graphene by means of friction, a current collector, and a battery. The positive electrode bus structure for a battery comprises: a plurality of positive electrode current collectors, one side of each of the positive electrode current collectors being provided with a positive electrode tab; a positive electrode bus plate, the positive electrode bus plate being provided on the positive electrode tab, and being suitable for rubbing against the positive electrode tab, so as to generate graphene, thereby increasing the conductive capability of the two, effectively reducing the internal resistance of a contact surface, and increasing an electronic transmission path, thereby significantly improving the electrochemical performance of a battery using the positive electrode bus structure for a battery.

Description

Battery positive electrode bus structure and current collector capable of generating graphene by friction and battery

Priority information

This disclosure requests the priority of a Chinese patent application filed with the State Intellectual Property Office of China on December 18, 2019, with a patent application number of 201911307413.3 and an application titled "Battery positive electrode confluence structure and current collector that can generate graphene by friction". And its entire content is incorporated into the present disclosure by reference.

Technical field

The present disclosure relates to the field of electrochemical devices. In particular, the present disclosure relates to a battery positive electrode bus structure, a current collector, and a battery that can generate graphene by friction.

Background technique

In water-based batteries, in addition to good electrical conductivity, the positive electrode current collector also needs to have strong oxidation resistance (the positive electrode material in the charged state has strong oxidation ability) and excellent resistance to electrolyte corrosion. Therefore, there are fewer metal materials suitable for use as a positive electrode current collector for water-based batteries. At present, in nickel-metal hydride, nickel-zinc, nickel-cadmium and other water-based batteries, foamed nickel is generally used as the cathode current collector for drainage. This material has complex processing techniques, scarce raw materials, and relatively expensive prices. Therefore, the cost of the positive electrode current collector limits the large-scale promotion and application of such batteries to a certain extent.

Graphite plates and graphite foils are both graphite products. They are inexpensive and have excellent properties such as electrical conductivity, oxidation resistance, and corrosion resistance. They are both ideal water-based battery cathode current collectors. However, their mechanical strength is weaker than that of metals, and they are more difficult to weld to metals. Therefore, in water-based batteries, for this type of current collector, if it is drawn out by conventional bolt fastening or metal welding, it is difficult to achieve, which greatly limits their application in water-based batteries. If conductive glue is used to connect the positive bus plate and the positive electrode tabs, since the conductive glue is generally made of a resin matrix with conductive fillers, there is a certain resistance, which will have obvious side effects on the aggregated current. If the ultrasonic welding technology is used to converge the battery, it is prone to corrosion.

In summary, the existing battery cathode bus structure and related components still need to be improved.

Public content

The present disclosure aims to solve one of the technical problems in the related art at least to a certain extent. To this end, an objective of the present disclosure is to propose a battery positive electrode bus structure and current collector that can generate graphene by friction, and a battery using the battery positive electrode bus structure or current collector.

In the first aspect of the present disclosure, the present disclosure proposes a battery cathode bus structure that can generate graphene by friction. According to an embodiment of the present disclosure, the battery positive electrode bus structure includes: a plurality of positive electrode current collectors, each side of the positive electrode current collector is provided with a positive electrode tab; a positive electrode bus plate, the positive electrode bus plate is arranged on the On the positive electrode tab, and suitable for friction with the positive electrode tab, so as to generate graphene. According to the battery positive electrode bus structure of the embodiment of the present disclosure, the positive electrode bus plate is in direct friction contact with the cross section of the positive electrode tab of each positive electrode current collector, and no conductive glue is used for connection. By rubbing the cross section of the positive electrode bus plate and the positive electrode tab, graphene can be generated on the cross section of the positive electrode tab (that is, the contact point between the positive electrode tab and the positive electrode bus plate) and both sides of the positive electrode tab according to the principle of mechanical peeling of graphite. The electrical conductivity of the two is increased, the internal resistance of the contact surface is effectively reduced, and the electron transmission path is increased, thereby significantly improving the electrochemical performance of the battery adopting the battery cathode bus structure.

In addition, the positive electrode confluence structure capable of generating graphene by friction according to the foregoing embodiments of the present disclosure may also have the following additional technical features:

In some embodiments of the present disclosure, the positive electrode current collector and the positive electrode bus plate are formed of graphite.

In some embodiments of the present disclosure, the positive electrode current collector is graphite foil.

In some embodiments of the present disclosure, the positive bus plate is a graphite plate.

In some embodiments of the present disclosure, the positive electrode bus structure further includes: a positive electrode drain wire, and the positive electrode drain wire is electrically connected to the positive electrode bus plate.

In the second aspect of the present disclosure, the present disclosure proposes a battery. According to an embodiment of the present disclosure, the battery includes the positive electrode bus structure of the above-mentioned embodiment. As a result, the battery can generate graphene through friction between the positive electrode bus plate in the positive electrode bus structure and the positive electrode tabs, thereby significantly improving electrochemical performance.

Based on the same inventive concept as the aforementioned "positive electrode confluence structure capable of generating graphene by friction", in the third aspect of the present disclosure, the present disclosure proposes a method for preparing a positive electrode current collector. According to an embodiment of the present disclosure, the method includes: providing a graphite foil; rubbing the surface of the graphite foil with a graphite plate to obtain the positive electrode current collector. Therefore, this method uses the graphite plate to rub the surface of the graphite foil. According to the principle of mechanical exfoliation of graphite, graphene can be produced on the surface of the graphite foil. The graphite foil rubbed by the graphite plate is used as the positive electrode current collector, which can significantly improve The electrical conductivity of the positive electrode current collector, and the combination of the positive electrode current collector and the positive electrode active material to prepare a battery can significantly improve the electrochemical performance of the battery.

In addition, the method for preparing a positive electrode current collector according to the foregoing embodiments of the present disclosure may also have the following additional technical features:

In some embodiments of the present disclosure, in the friction, the graphite plate is used to apply a vertical pressure of 0.001 to 0.01 MPa to the graphite foil.

In the fourth aspect of the present disclosure, the present disclosure proposes a positive electrode current collector. According to an embodiment of the present disclosure, the positive electrode current collector is prepared by the method for preparing a positive electrode current collector of the foregoing embodiment. Thus, the surface of the positive electrode current collector has graphene obtained by friction between the graphite plate and the graphite foil, so that the electrochemical performance is significantly improved.

In the fifth aspect of the present disclosure, the present disclosure proposes a battery. According to an embodiment of the present disclosure, the battery includes the positive electrode current collector of the above-mentioned embodiment. Therefore, the surface of the positive electrode current collector used in the battery has graphene obtained by friction between the graphite plate and the graphite foil, so that the electrochemical performance is significantly improved.

The additional aspects and advantages of the present disclosure will be partially given in the following description, and some will become obvious from the following description, or be understood through the practice of the present disclosure.

Description of the drawings

The above and/or additional aspects and advantages of the present disclosure will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, in which:

FIG. 1 is a schematic structural diagram of a positive electrode confluence structure capable of generating graphene by friction according to an embodiment of the present disclosure;

2 is a schematic structural diagram of a battery with a positive electrode bus structure capable of rubbing to generate graphene according to an embodiment of the present disclosure;

3 is a schematic diagram of a method for preparing a positive electrode current collector according to an embodiment of the present disclosure;

4 is an SEM image of graphene produced by friction at the cross section of the tab in Example 1;

Figure 5 is the battery cycle performance test results of Example 1 and Comparative Example 1;

Figure 6 is the battery rate performance test results of Example 1 and Comparative Example 1.

Detailed ways

The embodiments of the present disclosure are described in detail below. Examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the drawings are exemplary, and are intended to explain the present disclosure, but should not be construed as limiting the present disclosure.

In addition, the terms "first", "second", "third", "fourth", etc. are used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined with "first", "second", "third", and "fourth" may explicitly or implicitly include at least one of the features. In the description of the present disclosure, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

In the present disclosure, unless otherwise clearly defined and defined, terms such as "installation", "connected", "connected", and "fixed" shall be understood in a broad sense. For example, it may be a fixed connection or a detachable connection. Or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal communication of two components or the interaction relationship between two components, unless otherwise clear limited. For those of ordinary skill in the art, the specific meaning of the above-mentioned terms in the present disclosure can be understood according to specific circumstances.

In the present disclosure, unless otherwise clearly defined and defined, the first feature “on” or “under” the second feature may be in direct contact with the first and second features, or the first and second features may be indirectly through an intermediary. contact. Moreover, the "above", "above" and "above" of the first feature on the second feature may mean that the first feature is directly above or diagonally above the second feature, or it simply means that the level of the first feature is higher than that of the second feature. The “below”, “below” and “below” of the second feature of the first feature may mean that the first feature is directly below or obliquely below the second feature, or it simply means that the level of the first feature is smaller than the second feature.

In the first aspect of the present disclosure, the present disclosure proposes a battery cathode bus structure that can generate graphene by friction. According to an embodiment of the present disclosure, referring to FIG. 1, the battery positive electrode bus structure includes: a plurality of positive electrode current collectors 1 and a positive electrode bus plate 2, and a positive electrode tab 3 is provided on one side of each positive electrode current collector 1; 2 is arranged on the positive electrode tab 3 and is suitable for friction with the positive electrode tab 3 to generate graphene. According to the battery positive electrode bus structure of the embodiment of the present disclosure, the positive electrode bus plate is in direct friction contact with the cross section of the positive electrode tab of each positive electrode current collector, and no conductive glue is used for connection. By rubbing the cross section of the positive electrode bus plate and the positive electrode tab, graphene can be generated on the cross section of the positive electrode tab (that is, the contact point between the positive electrode tab and the positive electrode bus plate) and both sides of the positive electrode tab according to the principle of mechanical peeling of graphite. Increase the electrical conductivity of the two, and significantly improve the electrochemical performance (such as cycle performance, rate performance, etc.) of the battery adopting the battery cathode bus structure.

Preferably, the friction between the positive electrode bus plate 2 and the positive electrode tab 3 is performed by rotating the positive electrode bus plate 2, for example, the positive electrode bus plate 2 can be rotated in the direction of the curved arrow in FIG. 1. In some embodiments, the number of repeated rubbing between the positive electrode bus plate 2 and the positive electrode tab 3 is 1 to 5 times.

Preferably, during the process between the positive electrode bus plate 2 and the positive electrode tab 3, a vertical pressure of 0.001 to 0.01 MPa is applied to the positive electrode bus plate 2. Therefore, the friction effect between the positive electrode bus plate 2 and the positive electrode tab 3 can be further improved, which is further beneficial to the cross section of the positive electrode tab 3 (that is, the contact point between the positive electrode tab 3 and the positive electrode bus plate 2) and both sides of the surface. Produce graphene.

According to some embodiments of the present disclosure, the above-mentioned positive electrode current collector and positive electrode bus plate are formed of graphite. Therefore, it can further facilitate the friction between the cross section of the positive electrode bus plate and the positive electrode tab. According to the principle of mechanical peeling of graphite, the cross section of the positive electrode tab (that is, the contact point between the positive electrode tab and the positive electrode bus plate) and both sides of the surface Produce graphene.

According to some embodiments of the present disclosure, the above-mentioned positive electrode current collector is graphite foil.

According to some embodiments of the present disclosure, the above-mentioned positive busbar is a graphite plate.

According to some embodiments of the present disclosure, the above-mentioned positive electrode bus structure further includes: a positive electrode drain wire 4. The positive drain wire 4 is electrically connected to the positive bus plate 2.

According to a specific example of the present disclosure, referring to FIG. 2, the battery includes the positive electrode bus structure of the above-mentioned embodiment and the positive and negative electrode clusters 6. The positive and negative electrode cluster 6 includes a positive pole piece and a negative pole piece spaced apart from each other, wherein the negative pole piece includes a negative electrode tab 5.

In addition, it should be noted that the battery has all the features and advantages described above for the positive electrode bus structure of the battery, which will not be repeated here.

In the third aspect of the present disclosure, the present disclosure proposes a method of preparing a positive electrode current collector. According to an embodiment of the present disclosure, referring to FIG. 3, the method includes: providing a graphite foil 10; rubbing the surface of the graphite foil 10 with a graphite plate 20 to obtain the positive electrode current collector. Therefore, this method uses the graphite plate to rub the surface of the graphite foil. According to the principle of mechanical exfoliation of graphite, graphene can be produced on the surface of the graphite foil. The graphite foil rubbed by the graphite plate is used as the positive electrode current collector, which can significantly improve The electrical conductivity of the positive electrode current collector, and the combination of the positive electrode current collector and the positive electrode active material to prepare a battery can significantly improve the electrochemical performance of the battery (such as cycle performance, rate performance, etc.).

According to some embodiments of the present disclosure, in the process of horizontally rubbing the graphite foil by the graphite plate, the graphite plate may be used to apply a vertical pressure of 0.001 to 0.01 MPa to the graphite foil. In some embodiments, the number of repeated rubbing between the graphite plate and the graphite foil is 1 to 5 times.

In the fourth aspect of the present disclosure, the present disclosure proposes a positive electrode current collector. According to the embodiment of the present disclosure, the positive electrode current collector is prepared by the method for preparing the positive electrode current collector of the above-mentioned embodiment. Thus, the surface of the positive electrode current collector has graphene obtained by friction between the graphite plate and the graphite foil, so that the electrochemical performance is significantly improved.

In addition, it should be noted that all the features and advantages described above for the method for preparing the positive electrode current collector are also applicable to the positive electrode current collector, and will not be repeated here.

In the fifth aspect of the present disclosure, the present disclosure proposes a battery. According to an embodiment of the present disclosure, the battery includes the positive electrode current collector of the above-mentioned embodiment. Therefore, the surface of the positive electrode current collector used in the battery has graphene obtained by friction between the graphite plate and the graphite foil, thereby significantly improving electrochemical performance (such as cycle performance, rate performance, etc.).

In addition, it should be noted that the battery has all the features and advantages described above for the positive electrode current collector, which will not be repeated here.

The following describes the present disclosure with reference to specific embodiments. It should be noted that these embodiments are only descriptive and do not limit the present disclosure in any way.

Example 1

The positive electrode active material is LiMn ₂ O ₄ , the current collector is graphite foil, the graphite foil is reserved for the positive electrode tab 3; the negative electrode active material is metal Zn, the current collector is a copper mesh, and the copper mesh is reserved for the negative electrode tab 5; electrolyte It is an aqueous solution of 1mol/L Li ₂ SO ₄ + 2mol/L ZnSO _4. The contact between the positive electrode bus plate 2 and the positive electrode tab 3 is frictional contact. After rotating and rubbing for 5 times, the positive electrode bus plate is aligned to make the positive electrode tab 3 evenly contact the surface of the positive electrode bus plate 2. The SEM image of graphene produced by friction at the cross section of the tab is shown in Figure 4.

The material of the negative electrode tab 5 is copper mesh, and each negative electrode tab is connected together by soldering to converge.

Electrochemical performance test charge and discharge voltage range is 1.4 ~ 2.1V, 25 ℃ environment.

Comparative example 1

The battery was manufactured and tested in the same manner as in Example 1, except that the contact between the positive electrode bus plate and the positive electrode tabs was direct and vertical contact, and no mutual friction was performed.

The battery cycle performance of Example 1 and Comparative Example 1 is shown in Figure 5:

The cycle curve generated by rotating friction contact is relatively stable, the capacity is stable at 108～110mAh·/g, and the capacity retention rate of 30 cycles is 98.3% at a rate of 0.2C.

The specific capacity of the discharge generated by direct vertical contact is significantly reduced. After 15 cycles of charge and discharge, the capacity decreases significantly. At a rate of 0.2C, the capacity retention rate of 30 cycles is 96.7%.

The battery rate performance of Example 1 and Comparative Example 1 is shown in Figure 6:

The average specific capacity of the battery of Example 1 at 0.1C, 0.2C, 0.5C, 1C and back to 0.1C is 108.3mAh·/g, 106.7mAh·/g, 103.1mAh·/g, 98.9mAh·/g, respectively , 107.1mA·h/g. The capacity retention rate back to 0.1C was 98.9%.

The average specific capacity of the battery of Comparative Example 1 at 0.1C, 0.2C, 0.5C, 1C and back to 0.1C is 108.3mAh·/g, 106.6mAh·/g, 102.3mAh·/g, 97.2mAh·/g, respectively , 106.3mA·h/g. The capacity retention rate back to 0.1C was 98.2%.

The magnification performance produced by rotating friction contact is significantly better than direct vertical contact. Especially under the higher magnification of 0.5C and 1C, the capacity gap is more obvious.

Mechanism analysis:

Through rotating friction, a certain amount of graphene can be produced. Graphene increases the conductivity between the positive electrode bus plate and the positive electrode tabs and reduces the polarization, so the cycle and rate performance are improved significantly. In addition, the rotational friction can make each of the tabs contact the bus plate more fully, so that the positive electrode bus is not lost. However, direct vertical contact easily makes one or several of the many tabs contact poorly with the busbar, resulting in a loss of capacity. Moreover, the contact is insufficient, which increases the internal resistance and affects the magnification and cycle performance.

Comparative example 2

The battery was manufactured and tested in the same manner as in Example 1, except that the positive electrode bus plate and the positive electrode tab were combined by conductive glue. The 0.1～1C rate performance was tested, and the capacity retention rate was 95.8% when it returned to 0.1C. The specific capacity at 1C is 93.6mA·h/g.

Example 2

The battery was fabricated and tested in the same manner as in Example 1, except that the number of rotational friction between the positive electrode bus plate and the positive electrode tab was 2 times. Test the 0.1-C rate performance, and the capacity retention rate is 98.3% when it returns to 0.1C. The specific capacity at 1C is 97.7mA·h/g.

Example 3

The battery was fabricated and tested in the same manner as in Example 1, except that the surface of the graphite foil current collector was repeatedly rubbed with a graphite plate for 5 times before the positive electrode active material was combined with the graphite foil current collector. The 0.1～1C rate performance was tested, and the capacity retention rate was 99.1% when it returned to 0.1C. The specific capacity at 1C is 99.3mA·h/g.

On the basis of generating graphene by rotating and rubbing the cross-section of the graphite foil, the surface is subjected to friction treatment to also produce graphene, which makes the conductive performance of the graphite foil better and the rate performance further improved.

In the description of this specification, descriptions with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean specific features described in conjunction with the embodiment or example , Structures, materials, or characteristics are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples and the features of the different embodiments or examples described in this specification without contradicting each other.

Although the embodiments of the present disclosure have been shown and described above, it can be understood that the above-mentioned embodiments are exemplary and should not be construed as limiting the present disclosure. Those of ordinary skill in the art can comment on the foregoing within the scope of the present disclosure. The embodiment undergoes changes, modifications, substitutions, and modifications.

Claims

A positive electrode confluence structure capable of generating graphene by friction, which is characterized in that it comprises:

A plurality of positive electrode current collectors, each side of the positive electrode current collector is provided with a positive electrode tab;

A positive electrode bus plate, the positive electrode bus plate is arranged on the positive electrode tab, and is suitable for friction with the positive electrode tab, so as to generate graphene.
The positive electrode bus structure according to claim 1, wherein the positive electrode current collector and the positive electrode bus plate are formed of graphite.
The positive electrode bus structure according to any one of claims 1 to 2, wherein the positive electrode current collector is graphite foil.
The positive electrode bus structure according to any one of claims 1 to 4, wherein the positive electrode bus plate is a graphite plate.
The positive electrode bus structure according to any one of claims 1 to 4, further comprising: a positive electrode drain wire, and the positive electrode drain wire is electrically connected to the positive electrode bus plate.
A battery, characterized by comprising: the positive electrode bus structure according to any one of claims 1 to 5.
A method for preparing a positive electrode current collector, characterized in that it comprises:

Provide graphite foil;

A graphite plate is used to rub the surface of the graphite foil to obtain the positive electrode current collector.
8. The method according to claim 7, wherein in the friction, the graphite plate is used to apply a vertical pressure of 0.001 to 0.01 MPa to the graphite foil.
A positive electrode current collector, characterized in that the positive electrode current collector is prepared by the method according to any one of claims 7 to 8.
A battery, characterized by comprising the positive electrode current collector according to claim 9.