阅读说明：本技术 设置有压电元件的圆柱形二次电池 (Cylindrical secondary battery provided with piezoelectric element ) 是由 郑民基 成周桓 朴韩索 赵敏秀 于 2018-12-06 设计创作，主要内容包括：本文公开了一种圆柱形二次电池,包括：果冻卷型电极组件,果冻卷型电极组件配置为具有其中长片型正极和长片型负极在隔膜夹在正极与负极之间的状态下卷绕的结构；配置为容纳果冻卷型电极组件的圆柱形电池壳体；和压电元件,压电元件配置为由于果冻卷型电极组件的充电和放电引起的果冻卷型电极组件的体积膨胀而产生电能。(Disclosed herein is a cylindrical secondary battery including: a jelly-roll type electrode assembly configured to have a structure in which a long sheet type positive electrode and a long sheet type negative electrode are wound in a state in which a separator is sandwiched between the positive electrode and the negative electrode; a cylindrical battery case configured to receive the jelly-roll type electrode assembly; and a piezoelectric element configured to generate electric energy due to volume expansion of the jelly-roll type electrode assembly caused by charge and discharge of the jelly-roll type electrode assembly.)

1. A cylindrical secondary battery comprising:

a jelly-roll type electrode assembly configured to have a structure in which a long sheet type positive electrode and a long sheet type negative electrode are wound in a state in which a separator is interposed between the positive electrode and the negative electrode;

a cylindrical battery case configured to receive the jelly-roll type electrode assembly; and

a piezoelectric element configured to generate electric energy due to volume expansion of the jelly-roll type electrode assembly caused by charge and discharge of the jelly-roll type electrode assembly.

2. The cylindrical secondary battery according to claim 1, wherein the piezoelectric element is located between the jelly-roll type electrode assembly and the cylindrical battery case.

3. The cylindrical secondary battery according to claim 2, wherein the piezoelectric element is added to an adhesive tape configured to prevent the jelly-roll type electrode assembly from unwinding.

4. The cylindrical secondary battery according to claim 2, wherein the piezoelectric element is attached to an inner surface of the cylindrical battery case.

5. The cylindrical secondary battery according to claim 1, wherein

The cylindrical battery case includes an outer case and an inner case defining a hollow portion therebetween, and

the piezoelectric element is located in the hollow portion.

6. The cylindrical secondary battery according to claim 5, wherein the cylindrical battery case is configured such that a cylindrical side surface of the cylindrical battery case has a double structure including an outer case and an inner case, and such that a bottom surface of the cylindrical battery case has a single structure.

7. The cylindrical secondary battery according to claim 1, wherein the piezoelectric element is at least one selected from the group consisting of: natural piezoelectric materials, artificial piezoelectric crystals, lead-free piezoelectric ceramics, and artificial piezoelectric ceramics.

8. The cylindrical secondary battery according to claim 7, wherein the natural piezoelectric material is berlin's stone (AlPO)₄) Sucrose, quartz, rochelle salt, topaz, tourmaline, silk, enamel or dentin.

9. The cylindrical secondary battery according to claim 7, wherein the artificial piezoelectric crystal is gallium phosphate (GaPO)₄) Or lankshel (La)₃Ga₅SiO₁₄)。

10. The cylindrical secondary battery according to claim 7, wherein the lead-free piezoelectric ceramic is NaKNb, bismuth ferrite (BiFeO)₃) Sodium niobate (NaNbO)₃)、Bi₄Ti₃O₁₂Or Na_0.5Bi_0.5TiO₃。

11. According to claim 7The cylindrical secondary battery of, wherein the artificial piezoelectric ceramic is barium titanate (BaTiO)₃) Lead titanate (NbTiO)₃) Potassium niobate (KNbO)₃) Lithium niobate (LiNbO)₃) Lithium tantalate (LiTaO)₃) Sodium tungstate (Na)₂WO), zinc oxide (ZnO)₃)、Ba₂NaNb₅O₅Or Pb₂KNb₅O₁₅。

12. The cylindrical secondary battery according to claim 1, wherein the electrical energy generated by the piezoelectric element is stored in the jelly-roll type electrode assembly.

13. A battery pack comprising the cylindrical secondary battery according to any one of claims 1 to 12.

Technical Field

This application claims the benefit of korean patent application No. 2017-0166659, filed by 12/6/2017 at the korean intellectual property office, the disclosure of which is incorporated herein by reference in its entirety.

The present invention relates to a cylindrical secondary battery provided with a piezoelectric element, and more particularly, to a cylindrical secondary battery including a jelly-roll type electrode assembly mounted in a cylindrical battery case and a piezoelectric element generating electric energy due to volume expansion of the jelly-roll type electrode assembly caused by charge and discharge of the jelly-roll type electrode assembly.

Background

As mobile devices continue to be developed and the demand for mobile devices increases, secondary batteries capable of being charged and discharged have been widely used as energy sources for the mobile devices. In addition, as electric vehicles and hybrid electric vehicles have been developed to solve problems such as air pollution caused by existing gasoline and diesel vehicles using fossil fuel, secondary batteries have received significant attention as energy sources for electric vehicles and hybrid electric vehicles.

In general, secondary batteries are classified into cylindrical batteries having an electrode assembly mounted in a cylindrical metal can, prismatic batteries having an electrode assembly mounted in a prismatic metal can, and pouch-shaped batteries having an electrode assembly mounted in a pouch-shaped case made of an aluminum laminate sheet, based on the shape of a battery case.

The electrode assembly mounted in the battery case is a power generating element that includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode and that can be charged and discharged. The electrode assembly is classified into a jelly-roll type electrode assembly configured to have a structure in which a long-sheet type positive electrode and a long-sheet type negative electrode, to which an active material is applied, are wound in a state in which separators are disposed between the positive electrode and the negative electrode, or a stacking type electrode assembly configured to have a structure in which a plurality of positive electrodes having a predetermined size and a plurality of negative electrodes having a predetermined size are sequentially stacked in a state in which a plurality of separators are disposed between the positive electrodes and the negative electrodes, respectively. The jelly-roll type electrode assembly has advantages in that the jelly-roll type electrode assembly is easily manufactured and the jelly-roll type electrode assembly has a high energy density per unit weight. Therefore, the jelly-roll type electrode assembly has been widely used in the field where a high-capacity secondary battery must be applied.

That is, a cylindrical battery having a jelly-roll type electrode assembly received in a cylindrical battery case has been used to satisfy the demand for a battery having high energy density and high capacity. Since the cylindrical battery uses a metal can, which exhibits higher rigidity than the pouch-shaped battery, as a battery case, it is difficult to increase the size of a space defined in the battery. Unless a material having high energy efficiency is developed in a state where the utilization rate of the space defined within the cylindrical battery is not satisfactory as described above, it is difficult to increase the energy density of the cylindrical battery and to improve the energy efficiency of the cylindrical battery.

Korean registered patent No. 1261705 discloses a pouch-shaped battery including a battery case having a piezoelectric element layer that converts absorbed vibration into a voltage stored in a voltage storage unit so that self-charging can be performed when needed, and a protection circuit module having the voltage storage unit.

However, the above-described secondary battery is a pouch-shaped battery, which is different from a cylindrical battery, and further includes a separate element, such as a voltage storage unit, in order to store power generated by the piezoelectric element layer, which reduces the utilization rate of a space defined in the battery.

Korean registered patent No. 1708456 discloses a capacitor charging system including a piezoelectric element that generates power using pressure generated by a cell expansion phenomenon and a capacitor connected to the piezoelectric element, the capacitor receiving the power to perform charging. Since the piezoelectric element is located between the battery cells or between the battery cells and the module case, it is difficult to apply the piezoelectric element to the inside of the cylindrical battery.

Therefore, in the case of using a cylindrical battery having a higher energy density per unit weight, there is an urgent need for a technology that enables the battery to be self-charged without increasing the size of the battery and without requiring a separate storage space.

Disclosure of Invention

Technical problem

The present invention has been made in view of the above problems and other technical problems that have not yet been resolved, and it is an object of the present invention to provide a cylindrical secondary battery including a piezoelectric element that generates electric energy due to volume expansion of a jelly roll type electrode assembly caused by charge and discharge of the jelly roll type electrode assembly such that the cylindrical secondary battery performs autonomous power generation, in which the electric energy can be additionally generated in addition to the electric power generated by charging the jelly roll type electrode assembly accommodated in the cylindrical secondary battery.

Technical scheme

In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a cylindrical secondary battery comprising:

a jelly-roll type electrode assembly configured to have a structure in which a long sheet type positive electrode and a long sheet type negative electrode are wound in a state in which a separator is interposed between the positive electrode and the negative electrode; a cylindrical battery case configured to receive the jelly-roll type electrode assembly; and a piezoelectric element configured to generate electric energy due to volume expansion of the jelly-roll type electrode assembly caused by charge and discharge of the jelly-roll type electrode assembly.

That is, the cylindrical secondary battery according to the present invention uses a jelly-roll type electrode assembly that can be repeatedly charged and discharged. Accordingly, electric energy can be obtained as a result of charging the electrode assembly. In addition, in order to satisfy the demand for batteries having high capacity and high energy density, various efforts have been made to increase the energy density of cylindrical secondary batteries. However, it takes a long time to develop a material exhibiting high energy efficiency.

According to the present invention, a piezoelectric element is included in a cylindrical secondary battery, and generates energy due to a volume change of a jelly-roll type electrode assembly that repeatedly expands and contracts during charge and discharge of the electrode assembly. Therefore, the present invention has an advantage that the secondary battery can autonomously generate power when in use.

A piezoelectric element is a material in which a balance between positive and negative charges is lost, so that a potential difference occurs and thus electricity is generated. When pressure is applied to the piezoelectric element due to the expansion of the jelly-roll type electrode assembly, electric energy is generated.

According to the present invention, as described above, electric energy can be generated using the piezoelectric element in addition to the electric power generated by charging the jelly-roll type electrode assembly. Therefore, a cylindrical secondary battery having a high energy density can be provided without increasing the overall size of the secondary battery.

In a specific example, a piezoelectric element may be added to the cylindrical secondary battery so as not to increase the total volume of the cylindrical secondary battery. In view of the position of the piezoelectric element capable of generating electric power due to the volume expansion of the jelly-roll type electrode assembly, it is preferable to add the piezoelectric element to the inside of the battery case. For example, the piezoelectric element may be located between the jelly-roll type electrode assembly and the cylindrical battery case.

In the case where the piezoelectric element is disposed in contact with the jelly-roll type electrode assembly that repeats expansion and contraction during charge and discharge as described above, or in the case where the piezoelectric element is disposed adjacent to the jelly-roll type electrode assembly, pressure can be more accurately applied to the piezoelectric element, and the piezoelectric element can be added to a relatively large area, whereby the amount of electric energy generated by the piezoelectric element can be increased.

The area and location of the added piezoelectric element can be selectively applied. For example, a piezoelectric element may be added to an adhesive tape configured to prevent the jelly-roll type electrode assembly from being unwound. In the case where the piezoelectric element is added to the above position, the wound state of the jelly-roll type electrode assembly may be prevented from being released due to repeated expansion and contraction of the jelly-roll type electrode assembly, and electric energy may be additionally generated due to the piezoelectric element.

Further, a piezoelectric element may be attached to the inner surface of the cylindrical battery case. The piezoelectric element may be attached to the entire inner surface of the battery case, or may be attached only to the cylindrical side surface of the battery case.

The piezoelectric element may be added in the form of a tape having an adhesive layer formed on the surface opposite to the battery case, or may be added using a spray coating method.

In a particular example, the cylindrical battery case may include an outer case and an inner case defining a hollow portion therebetween, and the piezoelectric element may be located in the hollow portion. That is, the entire cylindrical battery case including the cylindrical surface and the bottom surface of the battery case may be configured to have a structure including an outer case and an inner case.

In addition, when considering the fact that the jelly-roll type electrode assembly expands in a centrifugal direction from the winding central axis thereof, the cylindrical battery case may be configured such that the cylindrical side surface of the cylindrical battery case has a double structure including an outer case and an inner case, and such that the bottom surface of the cylindrical battery case has a single structure, whereby only the piezoelectric element may be added to the cylindrical side surface of the cylindrical battery case.

The piezoelectric element may be at least one selected from the group consisting of: natural piezoelectric materials, artificial piezoelectric crystals, lead-free piezoelectric ceramics, and artificial piezoelectric ceramics.

Specifically, the natural piezoelectric material may be berlin's stone (AlPO)₄) Sucrose, quartz, Rochelle salt (Rochellesalt), sapphire, tourmaline, silk, enamel or dentin, and the artificial piezoelectric crystal may be gallium phosphate (GaPO)₄) Or lankshel (La)₃Ga₅SiO₁₄) The leadless piezoelectric ceramic may be NaKNb, bismuth ferrite (BiFeO)₃) Sodium niobate (NaNbO)₃)、Bi₄Ti₃O₁₂Or Na_0.5Bi_0.5TiO₃。

Artificial humanThe piezoelectric ceramic is barium titanate (BaTiO)₃) Lead titanate (NbTiO)₃) Potassium niobate (KNbO)₃) Lithium niobate (LiNbO)₃) Lithium tantalate (LiTaO)₃) Sodium tungstate (Na)₂WO), zinc oxide (ZnO)₃)、Ba₂NaNb₅O₅Or Pb₂KNb₅O₁₅。

In a specific example, the electrical energy generated by the piezoelectric element may be stored in a jelly-roll type electrode assembly. Since a separate member for storing electric energy generated by the piezoelectric element is not included, a cylindrical secondary battery having a higher energy density per unit volume can be provided.

According to another aspect of the present invention, there is provided a battery pack including a cylindrical secondary battery.

Specifically, the battery pack can be used as a power source for devices requiring the ability to withstand high temperatures, long life, high rate characteristics, and the like. Specific examples of the devices may include a mobile electronic device (mobile device), a wearable electronic device (wearable device), a power tool (power tool) driven by a battery-powered motor, an Electric Vehicle such as an Electric Vehicle (EV), a Hybrid Electric Vehicle (HEV), or a Plug-in Hybrid Electric Vehicle (PHEV), an Electric two-wheeled Vehicle such as an Electric bicycle (E-bike) or an Electric scooter (E-scooter), an Electric golf cart (electro golf cart), and an Energy Storage System (Energy Storage System). However, the present invention is not limited thereto.

The structure and manufacturing method of the device are well known in the art to which the present invention pertains, and thus, a detailed description thereof will be omitted.

Drawings

Fig. 1 is a vertical sectional view illustrating a cylindrical secondary battery according to an embodiment of the present invention.

Fig. 2 is a vertical sectional view illustrating a cylindrical battery case according to an embodiment of the present invention.

Fig. 3 is a vertical sectional view illustrating a cylindrical battery case according to another embodiment of the present invention.

Fig. 4 is a perspective view illustrating a jelly-roll type electrode assembly according to an embodiment of the present invention.

Fig. 5 is a perspective view illustrating a jelly-roll type electrode assembly according to another embodiment of the present invention.

Detailed Description

Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that the preferred embodiments of the present invention can be easily implemented by those of ordinary skill in the art to which the present invention pertains. However, in describing in detail the operation principle of the preferred embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention.

Wherever possible, the same reference numbers will be used throughout the drawings to refer to elements performing similar functions or operations. In addition, in the following description of the present invention, in the case where one element is expressed as being "connected" to another element, the one element may be not only directly connected to the other element but also indirectly connected to the other element via the other element. Furthermore, unless otherwise noted, "comprising" an element does not mean excluding the other elements, but rather means that the element can be included.

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

Fig. 1 is a vertical sectional view schematically illustrating a cylindrical secondary battery according to an embodiment of the present invention.

Referring to fig. 1, a cylindrical secondary battery, which is denoted by reference numeral 100, is configured to have a structure including a battery case 101, an electrode assembly 120 accommodated in the battery case 101, and a piezoelectric element 110 disposed between the battery case 101 and the electrode assembly 120, and the battery case 101 has a cylindrical single-layer structure including a closed bottom and an open top. The piezoelectric element 110 is also interposed between the lower surface of the battery case 101 and the electrode assembly 120. Alternatively, the piezoelectric element 110 may be interposed only between the side surface of the battery case 101 and the side surface of the electrode assembly 120.

For convenience of description, other internal elements constituting the cylindrical secondary battery are omitted from the drawings.

Fig. 2 and 3 are vertical sectional views schematically showing cylindrical battery cases according to various embodiments of the present invention.

Referring to fig. 2 and 3, each of the battery cases, which are denoted by reference numerals 200 and 300, is configured to have a cylindrical dual structure including a closed bottom and an open top.

The battery case 200 includes an outer case 201 and an inner case 202. A hollow portion is defined between the outer case 201 and the inner case 202, and a piezoelectric element 210 is disposed in the hollow portion. Each of the side and lower surfaces 205 of the battery case 200 includes an outer case 201 and an inner case 202.

The battery case 300 includes an outer case 301 and an inner case 302. A hollow portion is defined between the outer housing 301 and the inner housing 302, and a piezoelectric element 310 is disposed in the hollow portion. The side surface of the battery case 300 includes an outer case 301 and an inner case 302, but the lower surface 305 of the battery case 300 is configured to have a single layer.

Fig. 4 is a perspective view illustrating a jelly roll type electrode assembly according to an embodiment of the present invention, and fig. 5 is a perspective view illustrating a jelly roll type electrode assembly according to another embodiment of the present invention.

Referring to fig. 4, a jelly-roll type electrode assembly denoted by reference numeral 420 is shown in a state in which a piezoelectric element 410 is added to the entire outer surface of a wound sheet type electrode. As shown, the piezoelectric element 410 may be added 360 degrees around the outer surface of the jelly roll type electrode assembly. Alternatively, the length of the piezoelectric element may be shorter than the length of the jelly-roll type electrode assembly in the winding axis direction of the jelly-roll type electrode assembly in a state in which the piezoelectric element surrounds the outer surface of the jelly-roll type electrode assembly by 360 degrees.

Referring to fig. 5, a jelly-roll type electrode assembly denoted by reference numeral 520 is shown in a state in which a piezoelectric element 510 is added to an adhesive tape bonded to a winding end of the electrode assembly to prevent the electrode assembly from being released. In this case, in order to increase the size of the piezoelectric element, it is preferable to house the jelly-roll type electrode assembly in a battery case having the piezoelectric element attached to the inner surface thereof, such as the battery case 100 shown in fig. 1.

In the case of the piezoelectric element shown in fig. 1, 2, and 3, each of the outer cases 101, 201, and 301 corresponds to a negative electrode, and thus a negative (-) electrode of the piezoelectric element may be directly connected to each of the outer cases 101, 201, and 301. The positive (+) electrode of the piezoelectric element may be connected to the positive (+) electrode of the top cap of the cylindrical battery, or may be connected to a positive (+) electrode tab of the electrode assembly in parallel thereto.

In the case of the piezoelectric element shown in fig. 4 or 5, the positive (+) and negative (-) poles of the piezoelectric element may be directly connected to the positive and negative electrode tabs of the jelly-roll type electrode assembly 420 or 520 in parallel thereto.

As described above, the cylindrical secondary battery according to the present invention is configured to have a structure including a jelly-roll type electrode assembly and/or a piezoelectric element disposed in a battery case. Therefore, when the jelly-roll type electrode assembly expands during the charge and discharge of the secondary battery, pressure is applied to the piezoelectric element. Thus, a potential difference is formed, whereby electric energy can be generated.

Further, since the expansion and contraction of the jelly-roll type electrode assembly are repeated, the pressure may be repeatedly applied to the piezoelectric element. Thus, according to the charge-discharge cycle of the secondary battery, electric energy can be repeatedly generated by the piezoelectric element.

Hereinafter, the present invention will be described with reference to the following examples. This example is provided only for easier understanding of the present invention and should not be construed as limiting the scope of the present invention.

< example >

A cylindrical secondary battery configured such that the bottom surface of the battery case is provided to have a single layer, the side surface of the battery case includes an outer case and an inner case defining a hollow portion therebetween, and the piezoelectric element is disposed in the hollow portion as shown in fig. 2 is manufactured.

The cylindrical secondary battery is a 18650 type. That is, the outer diameter of the cylindrical secondary battery is 18mm, the height of the cylindrical secondary battery is 65mm, and the height of the side surface of the battery case where the piezoelectric element is provided, excluding the height of the cap assembly located at the upper portion of the cylindrical secondary battery, is 60 mm.

In the case where the thickness of the battery case is 0.15mm and the thicknesses of the outer case, the inner case, and the hollow portion are 0.05mm, and 0.05mm, respectively, the volume of the portion of the battery case where the piezoelectric element is provided can be calculated as follows.

V＝3.14x 18mm x 0.05mm x 60mm x 1cm³/1000mm³＝0.16956cm³

Typically, the energy density of the piezoelectric element when pressure is applied is 250 μ W/cm³. Therefore, 250. mu.W/cm can be obtained for the above battery case³x 0.16956cm³Energy of 0.4239mW when 42.39 μ W.

As described above, in the case of using the cylindrical secondary battery according to the present invention, electric energy may be generated due to physical volume expansion of the electrode assembly, in addition to energy generated by charging the secondary battery. Accordingly, a cylindrical secondary battery having an improved energy density may be provided without increasing the size of a battery cell.

Those skilled in the art to which the invention pertains will appreciate that various applications and modifications can be made based on the above description without departing from the scope of the invention.

Description of reference numerals

100: cylindrical secondary battery

101. 200 and 300: battery case

110. 210, 310, 410, 510: piezoelectric element

120. 420, 520: electrode assembly

201. 301: outer casing

202. 302: inner shell

205. 305: bottom surface of battery case

Industrial applicability

As is apparent from the above description, the cylindrical secondary battery according to the present invention is configured to have a structure in which a piezoelectric element generating electric energy due to volume expansion of the jelly-roll type electrode assembly caused by charge and discharge of the jelly-roll type electrode assembly is added to the jelly-roll type electrode assembly or to the battery case. Therefore, in addition to the generation of electric energy due to the charging of the secondary battery, it is possible to provide a cylindrical secondary battery capable of autonomous power generation, thereby significantly improving the energy density of the secondary battery.

The piezoelectric element according to the present invention delays the charge and discharge of the electrode assembly. Accordingly, the electrode assembly can be prevented from being deformed due to the charge and discharge of the electrode assembly.

In addition, since the electric energy generated by the self-power generation using the piezoelectric element is stored in the jelly-roll type electrode assembly, an additional storage space is not required. Therefore, it is possible to solve the problem that the energy density per unit volume of the cylindrical secondary battery is reduced due to the increase in volume of the cylindrical secondary battery.