Patent Application
20230072029
This application claims the benefit of Korean Patent Application No. 10-2020-0123679 filed on Sep. 24, 2020 and Korean Patent Application No. 10-2021-0112409 filed on Aug. 25, 2021 in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in their entirety.
The present disclosure relates to a winding device, and more particularly to a winding device for winding an electrode assembly.
Recently, as energy source price is increasing due to the depletion of fossil fuels and increasing interest is being paid to environmental pollution, the demand for environmentally-friendly alternative energy sources is bound to play an important role in the future life. Thus, research into techniques for generating various kinds of power, such as nuclear energy, solar energy, wind energy, and tidal power, is underway, and power storage apparatuses for more efficient use of the generated energy are also drawing much attention.
In particular, as technology development and demands for mobile devices increase, the demand for batteries as energy sources is rapidly increasing. Accordingly, many researches on batteries capable of meeting diverse demands have been conducted. In recent years, batteries have also been used in electric vehicles, and the use range is gradually expanded.
Typically, the demand for the lithium secondary battery, such as a lithium ion battery or a lithium ion polymer battery, which have advantages such as a high energy density, a discharge voltage, an output stability, and the like is high.
The secondary battery may be classified based on how the electrode assembly, having a structure in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are stacked, is structured. Typically, the electrode assembly may include a jelly-roll (wound) type electrode assembly in which long sheet type positive electrodes and long sheet type negative electrodes are wound with a separator being interposed therebetween, and a stacked (laminated) type electrode assembly in which a plurality of positive electrodes and negative electrodes, cut into predetermined unit sizes, are sequentially stacked with separators being interposed therebetween, and the like. Recently, in order to solve the problems involved in the jelly-roll type electrode assembly and the stacked type electrode assembly, there has been developed a stack/folding type electrode assembly having an improved structure, which is a combination of the jelly-roll type electrode assembly and the stacked type electrode assembly. The stack/folding type electrode assembly has a structure in which the positive electrodes and the negative electrodes taken in predetermined units are sequentially wound with separators being disposed between the two electrodes.
Further, the secondary battery is classified based on the shape of a battery case into a cylindrical battery having an electrode assembly mounted in a cylindrical case, a prismatic battery having an electrode assembly mounted in a prismatic case, or a pouch-shaped case having an electrode assembly mounted in a pouch-shaped case formed of an aluminum laminate sheet. Among them, the cylindrical battery and the jelly-roll type or stack/folding type electrode assemblies have an advantage of having high energy density.
In the fabrication of an electrode assembly including such a winding process, an electrode assembly can be fabricated by the process of inserting a laminate comprising a positive electrode, a negative electrode and a separator into a mandrel, winding the laminate around the mandrel and then removing the mandrel.
Referring to
In particular, recently, as the demand for a large-capacity battery increases and the electrode becomes larger, these problems are more serious.
It is an object of the present disclosure to provide a winding device that minimizes cracks occurring on electrodes and the like during winding process of an electrode laminate.
The objects of the present disclosure are not limited to the aforementioned objects, and other objects which are not described herein should be clearly understood by those skilled in the art from the following detailed description.
According to one embodiment of the present disclosure, there is provided an electrode winding device for winding an electrode laminate, comprising: a mandrel for winding the electrode laminate, the mandrel having a first end and a second end opposite the first end; a first rotation driver located at the first end of the mandrel to rotate the mandrel; and a second rotation driver located at the second end of the mandrel to rotate the mandrel.
The first and second rotation drivers may provide a rotational force to rotate the mandrel. At this time, the first and second rotation drivers may each independently rotate the mandrel, and the first and second rotation drivers may operate at a same rotation speed.
Here, each of the first and second rotation drivers may include a motor.
Each of the first and second rotation drivers may have a hollow having an inner diameter corresponding to an outer diameter of the mandrel such that the mandrel can be inserted in the hollows of the first and second rotation drivers and the first and second rotation drivers may be fastened to the mandrel in a state in which the mandrel is inserted.
The electrode laminate may include a sheet-type positive electrode, a sheet-type negative electrode, and a sheet-type separator interposed therebetween, or the electrode laminate may include unit cells arranged on a sheet-type separator.
The mandrel may be in the shape of a cylindrical rod.
In the winding device as described above, a torsion angle of the mandrel due to the rotation of the first and second rotation drivers may be 0.004 degrees or less, and a maximum stress acting on the electrode laminate by the rotation of the first rotation driver and the second rotation driver may be 15 MPa or less.
Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. The present disclosure can be modified in various different ways, and is not limited to the embodiments set forth herein.
Portions that are irrelevant to the description will be omitted to clearly describe the present disclosure, and like reference numerals designate like elements throughout the specification.
Further, in the drawings, the size and thickness of each element are arbitrarily illustrated for convenience of description, and the present disclosure is not necessarily limited to those illustrated in the drawings. In the drawings, the thickness of layers, regions, etc. are exaggerated for clarity. In the drawings, for convenience of description, the thicknesses of some layers and regions are shown to be exaggerated.
In addition, it will be understood that when an element such as a layer, film, region, or plate is referred to as being “on” or “above” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, it means that other intervening elements are not present. Further, the word “on” or “above” means disposed on or below a reference portion, and does not necessarily mean being disposed on the upper end of the reference portion toward the opposite direction of gravity.
Further, throughout the specification, when a portion is referred to as “including” a certain component, it means that the portion can further include other components, without excluding the other components, unless otherwise stated.
Further, throughout the specification, when referred to as “planar”, it means when a target portion is viewed from the upper side, and when referred to as “cross-sectional”, it means when a target portion is viewed from the side of a cross section cut vertically.
Hereinafter, with reference to
Referring to
The mandrel 100 winds up an electrode laminate. The electrode laminate may be formed by laminating a sheet-type positive electrode, a sheet-type negative electrode, and a sheet-type separator, or may be one in which unit cells are arranged on a sheet-type separator. The electrode laminate can be wound around the mandrel 100 to form a jelly-roll type or a stack/folding type electrode assembly. Such an electrode assembly may be inserted into a cylindrical battery case.
The unit cell means a mono-cell, which is an electrode or a laminate of one electrode and a separator, a bi-cell laminated so that electrodes of the same polarities are arranged at both ends, a full cell laminated so that electrodes of different polarities are arranged at both ends, and the like.
The mandrel 100 may be formed in the shape of a cylindrical rod. While the outer surface of the cylindrical rod rotates, the electrode laminate in contact with the outer surface can be wound up.
According to the present embodiment, the winding device includes first and second rotation driving units 200 and 300 formed at both ends of the mandrel 100 to rotate the mandrel 100. At this time, the first and second rotation driving units 200 and 300 provide a rotational force to the electrode laminate to rotate the mandrel 100. At this time, the first and second rotation driving units 200 and 300 each independently rotate the mandrel 100.
For example, the first and second rotation driving units 200 and 300 include motors M1 and M2, respectively, and the motors M1 and M2 can provide a rotational force to rotate the mandrel, 100.
Therefore, the rotational force of the mandrel 100 can be improved and the mandrel 100 can be rotated more precisely, thereby more facilitating the rotation control of the mandrel 100, as compared with the case of rotating the mandrel 100 using a single motor.
Further, according to the present embodiment, the rotation speeds of the first and second rotation driving units 200 and 300 may be the same. If the rotational speeds of both ends of the mandrel 100 that rotates by biaxial driving are different, cracks may occur due to an increase in the torsion angle of the mandrel 100 and an increase in the stress acting on the electrode laminate to be wound. Therefore, according to the present embodiment, by equalizing the rotation speeds of the first and second rotation driving units to minimize the torsion angle, it is also possible to reduce and disperse the acting stress applied to the electrode laminate to be wound.
The first and second rotation driving units 200 and 300 are not limited as long as they have a structure that can connect to the mandrel 100 and rotate the mandrel 100. However, it is more preferable that the mandrel 100 and the first and second rotation driving units 200 and 300 are detachably formed so that they can be easily replaced when they have been consumed. Therefore, for example, they may have a structure in which a hollow having an inner diameter corresponding to the outer diameter of the mandrel is formed so that the mandrel 100 is inserted.
Further, in such a structure, the mandrel 100 must be fixed so as to be fully operated by the rotational force of the first and second rotation driving units 200 and 300. Therefore, the first and second rotation driving units 200 and 300 may be mechanically fastened to the mandrel 100 in a state in which the mandrel 100 is inserted.
Conventionally, as shown in
On the other hand, according to the present embodiment, as shown in
Hereinafter, with reference to
Referring to
Specifically, when the winding device according to the present disclosure is used, the torsion angle of the mandrel may be 0.004 degrees or less. Even if the length of the mandrel increases as the size of the electrode laminate increases, according to the present disclosure which is a biaxial driving method, the torsion angle does not change significantly and can be maintained at a low value.
Further, referring to
Specifically, when using the winding device according to the present disclosure, a maximum stress acting on the electrode laminate by the rotation of the first and second rotation driving units may be 15 MPa or less. This maximum stress also increases as the size of the electrode laminate increases. Even if the length of the mandrel is increased, according to the present invention which is a biaxial driving method, it is possible to maintain a low value without a large change.
Therefore, the winding device of the present disclosure is more effective as the size of the electrode stack increases.
Through this, during the electrode winding process, the torsion angle of the mandrel is lowered through biaxial driving, and the stress acting on the electrode laminate are lowered and dispersed, thereby capable of minimizing cracks in the electrode laminate that occur through winding.
Although the invention has been shown and described above with reference to the preferred embodiments, the scope of the present disclosure is not limited thereto, and numerous other modifications and embodiments can be devised by those skilled in the art, which will fall within the spirit and scope of the principles of the invention described in the appended claims.
According to an embodiment of the present invention, there is provided a winding device capable of reducing cracks in an electrode stack through a twist angle reduction and load dispersing effect by providing a winding device capable of double-axial driving of the winding core during the winding process of the electrode stack.
Effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2020-0123679 | Sep 2020 | KR | national |
| 10-2021-0112409 | Aug 2021 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2021/011545 | 8/27/2021 | WO |
