TECHNICAE FIELD

Engineering technology related to a battery and a manufacturing method therefor

BACKGROUND OF THE INVENTION

A battery, especially a cylindrical battery such as an 18650 battery, is regarded as an energy storage device that are widely used commercially since such battery is considered a power source that is potential for applications and provides high capacity and energy density per weight. It also has a longer cycle life than other types of battery. Such battery is used in portable devices such as power banks for mobile phones, and in large electric devices such as plug-in hybrid vehicle or electric vehicle, etc. The cylindrical battery used in these large electric devices require energy storage of about 100 kWh for running. To this end, the battery that has high energy storage value and is safe for use is necessary for satisfying the growing energy demand.

Generally, a cylindrical battery pack consists of a cap, a metal case and a jellyroll wound electrode assembly, which comprises at least one strip of a cathode plate coated with an active material being a lithium compound, a lithium salt or a phosphate compound such as a lithium nickel cobalt aluminium oxide material (LiNi _x Co _y Al _z O2 : NCA) and a lithium nickel manganese cobalt oxide material (LiNi _x Mn _y Co _z O2 : NMC), etc.; at least one strip of an anode plate coated with a graphite, graphene or carbon compound with at least one strip of a separator being disposed in the center in order to prevent the cathode plate and the anode plate from contacting each other, which would result in a short circuit. Such separator allows only the lithium ion to displace. The separator is generally made of a plastic material such as polypropylene (PP) or polyethylene (PE), etc. There are two current collectors: one connected to the cathode plate and the cap, and the other connected to the anode plate and the bottom of the metal case. Such current collectors are made of a conductive material such as aluminium, copper and nickel, etc. They enable the electron to flow outside from the circuit. An electrolyte, which is an organic solution of salt having Li+ such as lithium hexafluorophosphate (LiPFe), lithium perchlorate (LiCICU), etc., enabling the passage of the lithium ion, which will be injected into such metal case.

At present, due to the increasing market demand for such battery, there is an attempt to develop to increase the efficiency of the battery. This will bring out the battery that provides a high level of safety, high energy capacity, stability, and a longer cycle life. Most of the developments focus on the materials used to create electrodes, particularly cathode, or the development of electrolyte, etc.

However, such lithium-ion battery still encounters problems when being used since the battery’s heat and internal resistance are still high. These make the battery deteriorate rapidly that it cannot supply sufficient electric current to meet the need. It may cause explosions easily, resulting in the decrease in the overall battery efficiency being used and the big loss of energy. Such problems rely on an appropriate condition in preparing electrodes, intracellular electrochemical reaction, and battery production and assembly, etc.

Therefore, there is an attempt to invent and develop guidelines of solutions to such aforementioned problems to improve the battery efficiency as disclosed in the following patent document examples.

US 2021210792 (Al) discloses a cylindrical battery comprising a wound electrode body, including at least one strip of the first electrode plate and at least one strip of the second electrode plate that are wound with a separator being disposed in the center. A bottom cylindrical outer covering plate capable of supporting the electrode body and the first polarity terminal attached to an opening portion of an outer cover through a first insulating member to close the opening portion. The electrode plates include a first core formed of a conductive material; and a first active material layer formed on the first core having the edge of the first core on the first polarity terminal side will be removed with respect to the edge of the first active material layer on the first polarity terminal side to create the first led-out portion. The first led-out portion includes a first bent portion that is bent towards the radially inner or outer side of the electrode body. A first surface of a first polarity current collector plate is in contact with the surface of the first bent portion at the first polarity terminal side. The first polarity terminal is connected directly or via a conductive member to the second surface of the first polarity current collector plate. This patent document designs for the core of the first electrode plate, which is one of a positive electrode plate or a negative electrode plate, to be thin and low in rigidity. This results in the ability to reduce internal resistance of the cylindrical battery.

CN 201877518 U discloses a cylindrical battery comprising a group of electrodes, a metal case, and an electrolyte, wherein the group of electrodes are disposed inside the metal case and the electrolyte is loaded into the metal case. The battery further comprises a porous electrolyte storage body, which is disposed in the metal case and the electrolyte is absorbed inside the cavity of the porous electrolyte storage body. The porous electrolyte storage body is inserted inside the cylindrical battery. The porous electrolyte storage body is a porous cylinder that is placed at the center of the group of electrodes or the bottom of the group of electrodes. The porous electrolyte storage body in such cylindrical battery can store more electrolytes and can supply them to the group of eletrodes along with drying the electrolytes in the group of electrodes to help making the turnover life of the cylindrical battery longer. Such body also holds the group of battery electrodes to enable them to maintain the level of an assembly of the group of battery electrodes and keep a good contact with the metal case; thereby helping to reduce internal resistance and improve the stability of the cylindrical battery.

CN 214625136 U discloses a cylindrical lithium battery comprising a metal case, a battery cell disposed in the metal case and a cover disposed on the top opening of the metal case. The metal case is welded to the anode of the battery cell. The cover is welded to the positive electrode of the battery cell. The battery cell is formed by winding a negative electrode plate, a diaphragm, and a positive electrode plate. The diaphragm is placed in the metal case. The bottommost edge of the negative electrode plate is a reserved exposed area with a predetermined height. The exposed area is bent towards the center of the battery cell to form the bent portion after the battery cell is welded. The outer surface of the bent portion is in a point connection with the cathode current collector and the cathode current collector is in a point connection with the bottom surface inside of the metal case. The lithium battery having such design is found to have an improved discharge rate, as well as reduced internal resistance and discharge temperature.

However, although there are invention and development of ways to improve the efficiency of the cylindrical battery such as improvement of the battery to having an internal resistance as disclosed in the above prior arts, there is still a need to develop and improve the cylindrical battery, particularly to reduce the internal resistance and the heat to increase the efficiency and satisfy the need to make such battery applicable for both current and future technologies.

SUMMARY OF THE INVENTION

In the first aspect, the present invention discloses a battery comprising: an electrode assembly comprising: an electrode body comprising a first end portion, a second end portion, and a cathode plate, an anode plate, and a separator that are stacked and wound together, with the separator being centered between the cathode plate and the anode plate; at least one strip of a first current collector; and at least two strips of a second current collector, a metal case having one open end for loading the electrode assembly internally; and a closure connected to the electrode assembly and sealing the open end of the metal case.

The first current collector has one end which is connected to the cathode plate and is disposed in a central region of the first end portion of the electrode body and another end which is connected to the closure.

The second current collector comprises a side current collector having one end which is connected to the anode plate and is disposed at an edge of the first end portion of the electrode body and another end which is connected to an inner surface of a side wall close to an edge of an open end of the metal case, and a bottom current collector having one end which is connected to the anode plate and is disposed at an edge of the second end portion of the electrode body and another end which is connected to an inner surface of a bottom wall of the metal case.

The second aspect of the present invention relates to a manufacturing method battery having the aforementioned characteristics, the method comprising:

(a) preparing the electrode body comprising the cathode plate, the anode plate, and the separator,

(b) welding at least one strip of the first current collector to the end of the cathode plate such that a protruding end is formed and welding at least two strips of the second current collector to the anode plate such that a protruding end of the second current collector protrudes from the opposite side

(c) winding together the cathode plate having the first current collector welded thereto, the anode plate having the second current collector welded thereto, and the separator to form a wound electrode assembly comprising the electrode body having the first current collector disposed in the central region of the first end portion of the electrode body and having one strip of the second current collector disposed at the edge of the first end portion of the electrode body to form the side current collector and the other strip of the second current collector is disposed at the edge of the second end portion of the electrode body to form the bottom current collector,

(d) loading the wound electrode assembly into the metal case on the open- end side,

(e) welding the wound electrode assembly to the metal case and the closure, and

(f) sealing the closure.

According to the present invention, the welding of the electrode assembly to the metal case comprises welding the protruding end of the first current collector to the closure and welding the protruding end of the side current collector of the second current collector to the inner surface of the side wall close to the end of the open end of the metal case and the protruding end of the bottom current collector of the second current collector to the inner surface of the bottom wall of the metal case.

With the features of the battery structure produced according to the present invention, the obtained battery can excellently withstand both high and low temperatures, and the internal resistance of the obtained battery is also reduced. This leads to a decrease in the loss of charging energy through the heat as well.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a vertical cross-section view of an exemplary battery of the present invention.

Fig. 2 is a vertical cross-section view of the electrode assembly of an exemplary battery of the present invention.

Fig. 3 is a top image showing a welding position of the current collector on the cathode plate according to an embodiment of the battery and the method according to the present invention.

Fig. 4 is a top image showing a welding position of the current collector on the anode plate according to an embodiment of the battery and the method according to the present invention.

Fig. 5 is a top image showing the back of the anode plate according to an embodiment of the battery and the method according to the present invention.

Fig. 6 is a top image showing the arrangement of the components of the electrode body to be wound and the winding direction according to an embodiment of the battery and the method according to the present invention. Fig. 7 is an image of the wound electrode assembly according to an embodiment of the battery and the method according to the present invention.

Fig. 8 is a top image showing the welding of the bottom current collector of the anode plate to the inner surface of the bottom wall of the metal case according to an embodiment of the battery and the method according to the present invention.

Fig. 9 is a top image showing the welding of the side current collector of the anode plate to the inner surface of the side wall close to the edge of the open end of the metal case according to an embodiment of the battery and the method according to the present invention.

Fig. 10 is a side image showing the welding of the current collector of the cathode plate to the closure according to an embodiment of the battery and the method according to the present invention.

DETAILED DESCRIPTION

Any aspects shown herein shall encompass the application to other aspects of the present invention as well, unless specified otherwise.

Any tools, devices, methods, materials, or chemicals mentioned herein, unless specified otherwise, mean the tools, devices, methods, materials, or chemicals generally used or practiced by a person skilled in the art, unless explicitly specified as special or exclusive tools, devices, methods, or chemicals for the present invention.

The terms “comprise(s)”, “consist(s) of’, “have/has”, “contain(s)”, and “include(s)” are open-end verbs. For example, any method which “comprises”, “consists of’, “has”, “contains”, or “includes” one component or multiple components or one step or multiple steps is not limited to only one component or one step or multiple steps or multiple components as specified, but also encompass components or steps that are not specified.

The present invention relates to a battery, especially a cylindrical battery, and a manufacturing method of said battery. The components of the battery including the arrangement and the assembly of components are illustrated in Figs. 1-10.

The battery according to the present invention comprises: an electrode assembly (1) comprising: an electrode body (1.1) comprising a first end portion (1.1.1), a second end portion (1.1.2), and a cathode plate (1.1.3), an anode plate (1.1.4) and a separator (1.1.5) that are stacked and wound together, with the separator (1.1.5) being centered between the cathode plate (1.1.3) and the anode plate (1.1.4), at least one strip of a first current collector (1.2), and at least two strips of a second current collector (1.3); a metal case (2) having one open end for loading the electrode assembly (1) internally; and a closure (3) connected to the electrode assembly (1) and sealing the open end of the metal case (2) wherein the first current collector (1.2) has one end which is connected to the cathode plate (1.1.3) and is disposed in a central region of the first end portion (1.1.1) of the electrode body (1.1) and another end which is connected to the closure (3).

The second current collector (1.3) comprises a side current collector (1.3.1) having one end which is welded to the anode plate (1.1.4) and is disposed at an edge of the first end portion (1.1.1) of the electrode body (1.1) and another end which is welded to an inner surface of a side wall close to an edge of the open end of the metal case (2) and a bottom current collector (1.3.2) having one end which is welded to the anode plate (1.1.4) and is disposed at an edge of the second end portion (1.1.2) of the electrode body (1.1) and another end which is welded to the inner surface of a bottom wall of the metal case (2).

In a preferred embodiment, the anode plate (1.1.4) comprises a copper foil having a coating (1.1.4.1), a front bare copper foil (1.1.4.2) and a back bare copper foil (1.1.4.3), wherein the front bare copper foil (1.1.4.2) and the back bare copper foil (1.1.4.3) are disposed on the same end of the anode plate (1.1.4), where the front bare copper foil (1.1.4.2) is the part where the second current collector (1.3) is welded. Preferably, the back bare copper foil (1.1.4.3) is the outermost part of the electrode body (1.1) when winding the cathode plate (1.1.3), the anode plate (1.1.4), and the separator (1.1.5) together.

The size of the bare copper foil can be adjusted according to the battery and the applications. By way of example, the front bare copper foil (1.1.4.2) may range from 2-3 cm in length and the back bare copper foil (1.1.4.3) may range from 5-8 cm in length.

According to a preferred exemplary embodiment, the side current collector (1.3.1) of the second current collector (1.3) connected to the inner surface of the side wall close to the edge of the open end of the metal case (2) is distanced from the edge of the open end of the metal case (2) in a range from 0.8- 1.0 cm. Preferably, the battery according to the present invention is a cylindrical battery, of which the electrode body (1.1) and the metal case (2) are shaped as a cylinder, wherein the cathode plate (1.1.3) ranges from 60-100 cm in length and ranges from 5.4-5.8 cm in width, and the anode plate (1.1.4) ranges from 65-105 cm in length and ranges from 5.6-6.0 cm in width, and the separator (1.1.5) ranges from 70-110 cm in length and ranges from 5.8-6.2 cm in width.

An example of material suitable for making the first current collector (1.2) is an aluminum strip. The material suitable for making the second current collector (1.3) is a nickel strip. The material suitable for making the separator (1.1.5) is a ceramic film.

The metal case (2) may be made of a stainless-steel material and may further comprise grooves (2.1) disposed circumferentially on the outer surface close to the open end of the metal case (2).

In addition, the battery may further comprise an electrolyte solution (4) provided inside the metal case (2) and comprise an encapsulating portion (5) disposed such that it at least partially encapsulates the metal case (2) and the closure (3).

Another aspect of the present invention relates to the manufacturing method of the battery having the characteristics according to the invention as described above.

The manufacturing method of the battery according to the present invention comprises:

(a) preparing the electrode body (1.1) comprising the cathode plate (1.1.3), the anode plate (1.1.4), and the separator (1.1.5),

(b) welding at least one strip of the first current collector (1.2) to the end of the cathode plate (1.1.3) such that a protruding end is formed and welding at least two strips of the second current collector (1.3) to the anode plate (1.1.4) such that a protruding end of the second current collector (1.3) protrudes from the opposite side,

(c) winding together the cathode plate (1.1.3) having the first current collector (1.2) welded thereto, the anode plate (1.1.4) having the second current collector (1.3) welded thereto, and the separator (1.1.5) to form a wound electrode assembly (1) comprising the electrode body (1.1) having the first current collector (1.2) disposed in the central region of the first end portion (1.1.1) of the electrode body (1.1) and having one strip of the second current collector (1.3) disposed at the edge of the first end portion ( 1.1.1 ) of the electrode body ( 1.1 ) to form the side current collector (1.3.1) and the other strip of the second current collector (1.3) disposed at the edge of the second end portion (1.1.2) of the electrode body (1.1) to form the bottom current collector (1.3.2),

(d) loading the wound electrode assembly (1) into the metal case (2) on the open-end side,

(e) welding the wound electrode assembly (1) to the metal case (2) and the closure (3), and

(f) sealing the closure (3).

The welding of the electrode assembly (1) to the metal case (2) comprises welding the protruding end of the first current collector (1.2) to the closure (3) and welding the protruding end of the side current collector (1.3.1) of the second current collector (1.3) to the inner surface of the side wall close to the edge of the open end of the metal case (2) and the protruding end of the bottom current collector (1.3.2) of the second current collector (1.3) to the inner surface of the bottom wall of the metal case (2).

According to a preferred embodiment, the anode plate (1.1.4) comprises the copper foil having the coating (1.1.4.1), the front bare copper foil (1.1.4.2) and the back bare copper foil (1.1.4.3), wherein at least two strips of the second current collector (1.3) are welded to the anode plate (1.1.4) in the front bare copper foil (1.1.4.2) region. The front bare copper foil (1.1.4.2) and the back bare copper foil (1.1.4.3) are disposed on the same end of the anode plate (1.1.4). Preferably, the back bare copper foil (1.1.4.3) is the outermost part of the electrode body (1.1) when winding the cathode plate (1.1.3), the anode plate (1.1.4), and the separator (1.1.5) together, and the separator (1.1.5) is disposed between the cathode plate (1.1.3) and the anode plate (1.1.4).

According to a preferred embodiment, the front bare copper foil ( 1.1.4.2) may range from 2-3 cm in length and the back bare copper foil (1.1.4.3) may range from 5-8 cm in length.

According to an exemplary embodiment, the welding of the side current collector (1.3.1) of the second current collector (1.3) to the inner surface of the side wall close to the edge of the open end of the metal case (2) is distanced from the edge of the open end of the metal case (2) in a range from 0.8- 1.0 cm.

Preferably, the winding of the cathode plate (1.1.3), the anode plate (1.1.4), and the separator (1.1.5) together is carried out by using an automatic winding machine to obtain the cylindrical electrode body (1.1), and the metal case (2) is shaped as a cylinder as well. By way of example, welding the electrode assembly (1) is carried out by using an ultrasonic spot welding with an electric power ranging from 5.0-7.0 kW.

The method according to the present invention may further comprise additional steps such as making a circumferential indentation in the metal case (2) on the outer surface close to the open end of the metal case (2) to form the grooves (2.1), adding the electrolyte solution (4) to an inside of the metal case (2), and encapsulating the metal case (2) and the closure (3) at least partially with an encapsulating portion (5) by any suitable methods such as heating at a temperature ranging from 100-140°C.

Hereinafter, the exemplary embodiments of the present invention will be described in more detail with reference to the examples, the test results and the appended drawings. These examples are not intended to limit the scope of the present invention in any way.

Preparation of the exemplary battery

Preparation of the electrode

Examples of the cathode plate and the anode plate were prepared by a known method of production. The preparation of the cathode plate and the anode plate is carried out by coating a mixture of an active material, conductive material, and binder in a solution onto a substrate of the cathode plate and the anode plate, drying the coated substrate, and extruding the substrate to obtain a desired thickness.

Battery assembling

The cathode plate and the anode plate obtained were assembled into an 18650 cylindrical battery. The assembly started with cutting the cathode plate and the anode plate into 5.6 and 5.8 cm in width, respectively, and 60-100 cm in length using an automatic cutter. Then, welding the ending region of the cathode plate with the current collector made of aluminum using a welding machine in a point welding, and welding the bare copper foil ending region of the anode plate with the current collector made of two strips of nickel using the same welding machine. Then, both the cathode plate and the anode plate were wound together with the separator made of a ceramic film being centered between such two electrodes to prevent a short circuit using an automatic winding machine to obtain the electrode assembly. The bare copper foil side with no current collector welded thereto is disposed on the outermost side when winding the cathode plate, the anode plate, and the separator together. The wound electrodes were then loaded into a metal case. Then, a characteristic welding was performed by welding the protruding end of the side current collector of the anode plate to the inner surface of the side wall close to the edge of the open end of the metal case and the protruding end of the bottom current collector of the anode plate to the inner surface of the bottom wall of the metal case. The cylindrical metal case having the electrode assembly loaded inside was then subjected to a grooving process. Then, a closure was welded to the protruding end of the current collector of the cathode plate. Then, the electrolyte was added in an amount of 5-6.5g per one battery to obtain a total weight of about 40-45 g in an atmosphere-controlled chamber with the humidity and oxygen level lower than 0.1 ppm. The electrolyte solution used was lithium hexafluorophosphate which was dissolved in a mixture of ethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate in a volume ratio of 1:1:1. An additive which is fluoroethylene carbonate was also added in an amount of 4% by volume. The battery was then charged using an automatic battery charger before wrapping the battery with a polyvinyl chloride (PVC) sheet at a temperature of 140°C in a belt oven.

Test

The exemplary cylindrical battery prepared from the above method was subjected to a safety test and internal resistance (IR) of the battery by comparing it to the comparative example, which is a conventional battery. The test results are described as follows.

Safety test of battery

The battery examples obtained according to the method of the present invention (Example 1-10) were subjected to a battery safety test using a temperature testing process (thermal test, T2) under the international testing standard UN 38.3.

Such temperature testing process (T2) was carried out by loading the battery for at least six hours in an environment with a temperature of 75°C and was continuously tested by loading the battery for at least six hours in the environment with a temperature of -40°C. The battery was then loaded for 24 hours in the environment with a temperature of 20°C. The test results are summarized in Table 1.

Table 1 shows the safety test results of the battery according to the present invention obtained by testing the battery examples of the invention at the temperature (T2) under the international testing standard UN 38.3.

Table 1

Note:

The battery that passed the test must comply with requirements. That is, the battery had no weight loss, breakage, leakage, was not flammable, had no detachment, and had a potential difference during open circuit potential (OCV) not below 90% of the value prior to the test. However, the requirements regarding voltage cannot be applied to the sample cell and the battery in the total discharged condition.

The purpose of the test is to examine the completion of the battery assembly and the efficiency of the internal electrical connection of the battery obtained from the method of the present invention. From the test results as shown in T able 1 , it was found that the battery obtained from the present invention had a potential difference during the open circuit potential over 90% or over 4.00 volt, which passed the test according to all requirements.

Internal resistance (IR) test

Examples of the battery obtained from the method of the present invention (Example 1-35) and examples of the comparative battery having a conventional internal structure (Comparative example 1-35) were subjected to determination of the internal resistance value.

The process of determining the internal resistance of the battery was carried out using the AC conductance test at a frequency of one kilohertz.

The test results obtained are summarized in Table 2.

Table 2 shows the internal resistance value (IR) for examples of battery prepared according to the present invention, and examples of the comparative battery having a conventional general internal structure. Table 2

In Table 2, it was found that the examples of battery prepared according to the method of the present invention have a lower average internal resistance of 44.7 mQ when compared to the average internal resistance of the comparative example battery which has the average internal resistance of 52.3 m . From the test results above, it can be seen that the battery having the current collector of the anode plate welded to the inner surface of the side wall close to the edge of the open end of the metal case, as well as having the outermost bare copper foil of the electrode assembly according to the present invention is able to help reducing the internal resistance of the battery up to about 14-15% compared to the comparative example battery, which has a conventional internal structure and current collector connection. That is, the battery having an interior design with the structure according to an embodiment of the present invention can reduce the internal resistance of the battery. This helps increasing the efficiency of the battery, reducing the loss of charging energy through the heat, and can prolong the cycle life of the battery. Also, the manufacturing method of the battery according to the present invention facilitating the battery manufacturing more conveniently and more simply; thereby increasing the opportunity of commercial and industrial applications.

The lithium-ion battery and the manufacturing method the same disclosed and claimed in the present invention intend to encompass the aspects of the invention obtained from actions, practices, modifications or alterations of any parameters without substantially different experiments from the present invention, and obtain those having properties, utilities and implementation similar to the aspects of the present invention corresponding to opinions of an ordinary person skilled in the art despite not being specifically identified in the claims. Therefore, what is interchangeable or similar to the aspects of the present invention include any slightly modifications or alterations apparent to an ordinary person skilled in the art should be considered as being under the intention, scope, and concept of the present invention as well.

BEST MODE OF THE INVENTION

Best mode of the invention is as described in the detailed description of the invention.