Patent Description:
A battery (such as an automotive battery) in general includes a plurality of battery cell. As a kind of battery cell, a cylindrical battery cell is used recently. For example, formfactors of the cylindrical battery cell may be from <NUM> (diameter is <NUM> and height is <NUM>) to <NUM> (diameter is <NUM> and height is <NUM>), and the cylindrical battery cell may at least include a cell housing and a jellyroll structure.

In general, the cylindrical battery cell needs to have a special current path within a cell design in order to ensure enough ampacity. Hence a resistive spot welding of an anode current collector to a steel cell housing is not applicable for larger cell sizes (e.g. <NUM> or larger). In some schemes, it is suggested to join a copper current collector and a steel cell housing by long welding seam created by a laser beam or an ultrasonic.

A cylindrical battery cell, battery and method for forming cylindrical battery cell is disclosed in <CIT>. This document relates to Art <NUM>(<NUM>) EPC, hence is not relevant to the question of inventive step.

However, the inventors found that in some existing schemes, there are several difficulties, challenges and risks in welding copper to steel. For example, copper and steel have quite different melting points (<NUM> vs. <NUM>). Almost <NUM> difference in melting point makes a proper adjustment of laser beam intensity rather challenging. Furthermore, joining/welding can be only achieved, in case a laser beam hits a copper surface. This means, the joining of a cell housing and a copper current collector cannot be performed from outside of the cell housing. Furthermore, welding of Cu and Nickel-Plated Steel can affect Nickel coating, which potentially introduce risk of corrosion of cell housing, which in terms may potentially lead to cell internal short circuit by transportation of corrosion products.

In order to solve at least part of the above problems, methods and devices are provided in the present invention. Features and advantages of embodiments of the present invention will also be understood from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the present invention.

In general, the present invention provides a cylindrical battery cell, a battery and a method for forming cylindrical battery cell. It is expected to join/weld the cell housing with the jellyroll structure by using a laser from outside of the cell housing, while risk of corrosion of cell housing is not introduced.

In a first aspect, a cylindrical battery cell according to claim <NUM> is provided.

In some embodiments, the copper plate is welded with the jellyroll structure by using a laser from outside of the cell housing.

In some embodiments, a thickness of the copper plate is determined according to a thickness of a flattened tab of the jellyroll structure on a bottom side of the jellyroll structure.

In some embodiments, one or more flattened tabs of the jellyroll structure are welded with the copper plate by using a laser after the jellyroll structure is inserted into the cell housing.

In some embodiments, one or more flattened tabs of the jellyroll structure are pre-welded with a copper current collector on a bottom side of the jellyroll structure, and the copper plate is welded with the copper current collector by using a laser after the jellyroll structure is inserted into the cell housing.

In some embodiments, the cell housing is made up of steel, and the bi-metal plate is formed by using a forging process on the bottom side of the cell housing.

In a second aspect, a method for forming cylindrical battery cell according to claim <NUM> is provided.

In a third aspect, a battery according to claim <NUM> is provided.

According to various embodiments of the present invention, a copper plate is forged with the cell housing to form a bi-metal plate on the bottom side of the cell housing, and the copper plate is welded with the jellyroll structure. Therefore, joining/welding the cell housing with the jellyroll structure is achieved by using a laser from outside of the cell housing, while risk of corrosion of cell housing is not introduced.

The above and other aspects, features, and benefits of various embodiments of the invention will become more fully apparent, by way of example, from the following detailed description with reference to the accompanying drawings, in which like reference numerals or letters are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the invention and not necessarily drawn to scale, in which:.

The present invention will now be described with reference to several example embodiments. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present invention, rather than suggesting any limitations on the scope of the present invention.

It should be understood that when an element is referred to as being "connected" or "coupled" or "contacted" to another element, it may be directly connected or coupled or contacted to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" or "directly contacted" to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., "between" versus "directly between", "adjacent" versus "directly adjacent", etc.).

As used herein, the terms "first" and "second" refer to different elements. The terms "comprises," "comprising," "has," "having," "includes" and/or "including" as used herein, specify the presence of stated features, elements, and/or components and the like, but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

The term "cover" is to be read as "at least in part cover".

In this invention, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong.

A cylindrical battery cell is provided in the embodiments.

<FIG> is a diagram which shows a cylindrical battery cell <NUM> in accordance with an embodiment of the present invention. <FIG> is a diagram which shows a section view of the cylindrical battery cell <NUM> in accordance with an embodiment of the present invention.

As shown in <FIG>, a cylindrical battery cell <NUM> at least includes: a cell housing <NUM> and a jellyroll structure <NUM>. The cell housing <NUM> have a cylindrical lateral portion <NUM> and a bottom portion <NUM>.

The jellyroll structure <NUM> is arranged inside the cell housing <NUM>. For example, the jellyroll structure <NUM> includes a rolled anode foil, a rolled cathode foil and a rolled separator between the rolled anode foil and the rolled cathode foil. As for the detail of the jellyroll structure <NUM>, please refer to relevant art.

As shown in <FIG>, a copper plate <NUM> is forged with the bottom portion <NUM> inside of the cell housing <NUM> to form a bi-metal plate on a bottom side of the cell housing <NUM>, and the copper plate <NUM> is welded with the jellyroll structure <NUM>.

For example, the bi-metal plate is formed by the copper plate <NUM> and the bottom portion <NUM> of the cell housing <NUM>. The bi-metal plate is a cu-steel plate while the copper plate <NUM> is arranged inside of the cell housing <NUM>.

It should be appreciated that some components or elements are illustrated only as examples in <FIG>. However, it is not limited thereto, for example, connections or positions of the components or elements may be adjusted, and/or, some components or elements may be omitted. For example, the cylindrical battery cell <NUM> may include a cap component, and it is not limited thereto.

In this invention, the bi-metal plate is formed at the bottom side of the cell housing <NUM>, and the copper plate <NUM> is welded with the jellyroll structure <NUM> by using a laser from outside of the cell housing <NUM>. Therefore, joining/welding the cell housing with the jellyroll structure is achieved by using a laser from outside of the cell housing, while risk of corrosion of cell housing is not introduced.

In this invention, a laser is used to weld the copper plate <NUM> inside of the cell housing <NUM> with the jellyroll structure <NUM>, but it is not limited thereto. For example, other ways such as an ultrasonic may be used in the welding process.

In some embodiments, the copper plate <NUM> is welded with the jellyroll structure <NUM> by using a laser from outside of the cell housing <NUM>. For example, as shown in <FIG>, some dots <NUM> are used to demonstrate laser welding footprints.

In some embodiments, a thickness of the copper plate is determined according to a thickness of a flattened tab of the jellyroll structure on a bottom side of the jellyroll structure. For example, the shape/thickness of copper plate <NUM> can be adjusted by tooling on demand according to requirement.

In some embodiments, one or more flattened tabs of the jellyroll structure are welded with the copper plate by using a laser after the jellyroll structure is inserted into the cell housing. For example, there is not a pre-welded copper current collector.

As shown in <FIG>, there are one or more flattened tabs <NUM> in the jellyroll structure <NUM> one the bottom side of the jellyroll structure <NUM>. The flattened tabs <NUM> of the jellyroll structure <NUM> are welded with the copper plate <NUM> by using a laser after the jellyroll structure <NUM> is inserted into the cell housing <NUM>.

Therefore, the copper plate (Cu) inside of the cell housing will be laser welded to the tabs (Cu) afterwards, such that there is not difference in melting point when welding. Furthermore, a copper current collector is intendedly not considered in this example. The copper plate inside of the cell housing will be directly laser welded to the flattened copper tabs of the jellyroll structure. Consequently, a manufacturing process, welding a current collector (Cu) to tabs is skipped, which reduces manufacturing costs.

In some embodiments, a thickness (D1) of the copper plate <NUM> is equal to a thickness (D2) of the cell housing <NUM>, or is smaller than a predetermined threshold (T1). For example, D1 = D2, or D1 < T1, and it is not limited thereto.

For example, the flattened tabs <NUM> of the jellyroll structure <NUM> are pre-welded with a copper current collector on the bottom side of the jellyroll structure <NUM>, and the copper plate <NUM> is welded with the copper current collector by using a laser after the jellyroll structure <NUM> is inserted into the cell housing <NUM>.

Therefore, the copper current collector is pre-welded to the flattened copper tabs. The copper plate (Cu) inside of the cell housing will be laser welded to the copper current collector (Cu) afterwards, such that there is not difference in melting point when welding.

In some embodiments, the cell housing is made up of steel, and the bi-metal plate is formed by a forging process on the bottom side of the cell housing. However, it is not limited thereto.

In this invention, copper is configured inside of a cell housing by a bi-metal forging process. For example, a copper plate is forged on the bottom side of the cell housing. The shape and thickness of the copper plate can be adjusted by tooling. Different shape and thickness of the copper plate may provide and enhance variety of cell properties, regarding thermal management and cooling system.

After inserting of the jellyroll structure into the cell housing, cell bottom (copper plate) can be penetration laser welded directly to the jellyroll structure, from outside of the cell housing. For example, the jellyroll structure can be pre-welded its own current collector (copper disk). For another example, it is possible to laser weld the copper plate directly to flattered tabs.

In this invention, joining of a copper plate to a steel cell housing by enabling laser welding from outside of the cell housing can be achieved, and the risk of corrosion within cell can be eliminated. Furthermore, the technique solution of this invention can maximize a space usage at the bottom side of the cell housing (higher volumetric filling ratio, higher energy content per cell, lower cost per cell mechanic).

In addition, the technical solution enhances substantially a thermal conduction path at the cell bottom. Concurrently, a high in-plane thermal conduction of jellyroll structure (in vertical axis) is achieved, this enables implementation of bottom cooling at module/pack level.

For example, implementation of bottom cooling increases volumetric filling ratio at module/pack level by minimize <NUM>%. Implementation of bottom cooling resolves many technical challenges in integration and reduces manufacturing costs.

It is to be understood that, the above examples or embodiments are discussed for illustration, rather than limitation. Those skilled in the art would appreciate that there may be many other embodiments or examples within the scope of the appended claims.

It can be seen from the above embodiments, a copper plate is forged with the cell housing to form a bi-metal plate on the bottom side of the cell housing, and the copper plate is welded with the jellyroll structure. Therefore, joining/welding the cell housing with the jellyroll structure is achieved by using a laser from outside of the cell housing, while risk of corrosion of cell housing is not introduced.

A method for forming cylindrical battery cell is provided in the embodiments. The corresponding devices are illustrated in the first aspect of embodiments, and the same contents as those in the first aspect of embodiments are omitted.

<FIG> is a diagram which shows a method for forming cylindrical battery cell in accordance with an embodiment of the present invention. As shown in <FIG>, a method <NUM> for forming cylindrical battery cell includes:.

<FIG> is a diagram which shows a cell housing with a copper plate in accordance with an embodiment of the present invention. As shown in <FIG>, a copper plate <NUM> is inserted into the cell housing <NUM>.

As shown in <FIG>, a method <NUM> for forming cylindrical battery cell includes:.

As shown in <FIG>, a method <NUM> for forming cylindrical battery cell includes:
<NUM>, inserting a jellyroll structure into the cell housing.

<FIG> is a diagram which shows a cell housing and a jellyroll structure in accordance with an embodiment of the present invention. As shown in <FIG>, the jellyroll structure <NUM> is inserted into the cell housing <NUM>.

<FIG> is another diagram which shows a cell housing and a jellyroll structure in accordance with an embodiment of the present invention. As shown in <FIG>, after the jellyroll structure <NUM> is inserted into the cell housing <NUM>, a force <NUM> is applied to insure a gap-free interface between the bi-metal plate (the bottom portion <NUM> and the copper plate <NUM>) of the cell housing <NUM> and the tabs <NUM> of the jellyroll structure <NUM>.

As shown in <FIG>, a method <NUM> for forming cylindrical battery cell includes:
<NUM>, welding the copper plate and the jellyroll structure on the bottom side of the cell housing.

As shown in <FIG>, the copper plate <NUM> inside of the cell housing <NUM> is weld (some dots in <FIG> are used to demonstrate laser welding footprints) with the jellyroll structure <NUM> by using a laser from outside of the cell housing.

It should be appreciated that <FIG> is only an example of the invention, but it is not limited thereto. For example, the order of operations at blocks or steps may be adjusted, and/or, some blocks or steps may be omitted. Moreover, some blocks or steps not shown in <FIG> may be added.

Furthermore, some components or elements are illustrated only as examples in <FIG>. However, it is not limited thereto, for example, connections or positions of the components or elements may be adjusted, and/or, some components or elements may be omitted.

A battery is provided in the embodiments. The corresponding devices and the method are illustrated in the first and second aspects of embodiments, and the same contents as those in the first and second aspects of embodiments are omitted.

In some embodiments, the battery includes a plurality of the cylindrical battery cell. The cylindrical battery cell is illustrated according to the first aspects of embodiments.

<FIG> is a diagram which shows a battery <NUM> in accordance with an embodiment of the present invention. As shown in <FIG>, the battery <NUM> may include a plurality of the cylindrical battery cell <NUM>.

It should be appreciated that <FIG> is only an example of the invention, but it is not limited thereto. For example, some components or elements are illustrated only as examples in <FIG>. However, it is not limited thereto, for example, connections or positions of the components or elements may be adjusted, and/or, some components or elements may be omitted.

Further, it is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and integrated circuits (ICs) with minimal experimentation.

Generally, various embodiments of the present invention may be implemented in hardware or special purpose circuits, software, logic or any combination thereof.

While various aspects of embodiments of the present invention are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present invention, but rather as descriptions of features that may be specific to particular embodiments.

Claim 1:
A cylindrical battery cell, at least comprising:
a cell housing (<NUM>) having a cylindrical lateral portion and a bottom portion, said bottom portion being provided with no opening; and
a jellyroll structure (<NUM>) which is arranged inside the cell housing (<NUM>);
characterized in that said cylindrical battery cell comprises << forging a copper plate (<NUM>) with the bottom portion, inside of the cell housing (<NUM>) >> a bi-metal plate on a bottom side of the cell housing (<NUM>) formed by << - >> ; and in that said copper plate (<NUM>) is welded with the jellyroll structure (<NUM>).