WO2013122448A1

WO2013122448A1 - Lithium-ion battery

Info

Publication number: WO2013122448A1
Application number: PCT/MY2012/000295
Authority: WO
Inventors: Mohd Ali SULAIMAN; Azrulnizam MAT; Nurhaswani ALIAS
Original assignee: Sirim Berhad
Priority date: 2012-02-14
Filing date: 2012-12-10
Publication date: 2013-08-22
Also published as: AU2012370347B2; AU2012370347A1; KR20140125862A; MY164650A

Abstract

There is disclosed a lithium-ion battery (1) that is assembled within a casing (11) comprising at least one bare cell (12) and each of bare cell (12) comprises at least an anode plate (21) and cathode plate (22) alternatively arranged between a. separator (23), a connector (13) is connecting each of the anode (21) and cathode plates (22) together in accordance to their respective polarity to form a pair of bus bar plates (14). The bus bar plates. (14) is positioned along the edge of bare cell (12) and bus bar plates (14) is provided with a plurality of slits (15). Each of the anode plates (21) and cathode plates (22) is provided with a tab (25). This tab (25) having similar polarity are arranged together to form stack of similar polarity tabs along the edge of the bare cell (12). A method of fabricating a lithium ion battery (1) is also disclosed and comprising the steps of preparing bare cell (12), arranging at least one bare cell (12) to form one or multi-stack of bare cells (81) and positioning a connector means (13) to connect each of the anode (21) and cathode plates (22) together in accordance to their respective polarity.

Description

LITHIUM-ION BATTERY

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to lithium-ion battery, and more particularly to a lithium-ion having a configuration in which multi-stack of bare cell are stacked in parallel and provided · with tab that allows plates of the bare cells to connect together to form a high capacity lithium-ion battery. The present invention also relates to a method of fabricating lithium-ion battery of the same.

2. BACKGROUND OF THE INVENTION

Lithium-ion batteries are rechargeable batteries also known as secondary cell batteries used as an energy source that can be found in many configurations, shapes and^' sizes. Lithium-ion batteries are common in consumer electronics. They are one of the most · popular types of rechargeable battery for portable electronics., such as cellular phones, cameras, camcorders and^'., note^'boo.ks , with^' one ; of the best energy densities, no memory effect, and a slow loss of charge' when not in use. With recent development, this battery turned its way to- a new dimension of high power applications such as uninterruptable power supply (UPS) for telecommunication tower stations, energy- storage for renewable energy, and also for various sizes of electric, vehicles, which require a new concept of batteries and new electrode properties to improve capacity and specific energy density. Lithium-ion- battery developed in the .1990's ^'has become increasingly popular because it has higher ^' operating voltage and energy density compared to Ni-MH, Ni-Cd and sulfuric acid-lead batteries that use aqueous solution electrolyte. A major- drawback of lithium-ion battery is the cylindrical and prismatic shape of the battery requires attention on the performance of battery and^' the safety issue of the battery. Despite the popular usage of the cylindrical-type lithium-ion battery, many instances have been reported . of the unpredictable explosion of these batteries. These explosions have been attributed to a temporary increased in the inner pressure within the battery. Further, this structure has .small radius of curvature at the center portion of the spiral which often results in extreme stresses at the bending surface of the electrode, often causing peeling of the electrode. In addition to the above, to fabricate high capacity ^' battery, there is required a very long electrode plate, which causes an increased in the internal impedance due to the longer electron path. Besides that, a- prismatic lithium ion battery is . reported to have lower capacity density and^' specific energy compared to cylindrical one. The capacity of the battery is generally proportional to^' the amount of the electrode active materials.

Recent development also pointed to the typically ^' high cost of manufactured of lithium ion-battery. In traditional lithium-ion battery technologies, they use arrangement of many cells ^" connected in series or parallel according to the required supplementary system. This will cause higher cost due to the additional process steps and additional material utilized in the finished cell. There are also some weak point of the most critical process that needs a lot of intention and precaution especially in the sealing process. The . conventional sealing of a battery sometimes facing many problems including generation of gas inside battery, peeling at the sealed of area and it affect the reliability and safety of the battery itself. From the welding point of view, the most important factors of tab welding are thickness and material of both the tab and the terminal. In battery manufacturing, there are some requirements for materials joining which depends on the type of material, size, capacity of battery such as the tab to terminal connections and external electrical connection. The welding challenges arise due to the limited electrode thickness that can be weld to form a high power lithium-ion battery.

It is therefore an object, of the present invention to provide a cell structure ^' and a method for the manufacturing thereof that is more convenient and reduced time due to reduced process involved during production of lithium-io battery which proportional .to cost reduction.- Next, the high power lithium ion battery can be manufactured using multi stack cell together with welding method even for a high capacity which involve finished cell in small .size. Further, the welding technique allows the layering. structure of bare cells to be stably Connected to each other without an additional support or connecting device. Besides that, it forms a flexible and rigid full cell that has a strong and solid structure. Further, ^" the present invention overcomes the problem of long winding plate jellyroll system in traditional lithium ion battery that imposes high internal impedance and limitation■ in layer welding in lithium polymer battery.

3. SUMMARY OF THE INVENTION

It is an object of the present -invention to provide a high power lithium-ion battery with multi stack bare cells structure, which, contain two or more bare cells connected in parallel.

It is another object of .the present invention to provide a method of producing lithium-ion battery that is convenient to manufacture and reduced time of processing due to the less process involved during production of the high power lithium-ion battery which generally proportional to cost reduction.

Yet, it is another object of the present invention to provide a method of prepared lithium-ion battery via various methods either by enveloped separator method, zigzag method, winding method or flatten jellyroll method.

Yet, it is- another object of the- present invention to provide a method of producing lithium ion ^'battery having stable and dependable cell structure.

It is also another -object of the present invention to provide a method of producing lithium-ion battery with shortened manufacturing process by eliminating few processing steps that also reduces manpower, machinery, materials processing time requirements and also lowered rej ect^■ rate .

These and other objects of the present invention are accomplished by providing,

A lithium-ion battery (1) assembled within a casing (11) , said lithium-ion battery (1) comprising: at least one bare cell (12), each of said bare cell (12) comprises of at least an anode plat-e and cathode plate alternatively arranged between a separator (23) ; and a connector means (13) connecting each of said anodes and cathode plates together in accordance to their respective polarity; characterized in that, said connector means (13) is formed as a pair of bus bar plates (14) where the bus bar plates (14) are arranged along the edge of said bare cell

(12) and said bus bar plate is provided with a plurality of slits (15) .

And ;

A method of fabricating a lithium-ion battery comprising the steps of; a) preparing a - bare cell (12) that comprises of at least, an anode plate and cathode plate alternatively arranged between a separator (23); b) arranging at least one^' of said bare cell (12) to form one or ^■ multi-stack of bare ^■ cells (81); c) positioning a connector means (13) to connect each of said anode and cathode plates together in accordance to their respective polarity; characterized in that, said connector means (13) is formed as a pair of bus bar plates (14) where the bus plates (14)_. is each positioned along the edge of said bare cell (12) and said bus bar- plate (14) is provided with a plurality of slits (15), and each of said anode plates and cathode plates is provided with a tab

(25) disposed at the edge of the plate and the tabs having similar polarity ..aire arranged together to form another stack of similar polarity tabs (25) along the edge of the bare cells (12) while tabs having another similar polarity are arranged together to form another stack of similar polarity tabs (25) along the edge of said bare cells; and inserting said tabs (25) into the respective slit (15) of said bus bar plate (14) and welding said tabs (25) to said bus bar plate (14) . BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of- the invention will now be described, by way of example only, with reference to the accompanying figures in which:

Figure 1 shows perspective view of a lithium ion battery configured according to the embodiment of the present invention;

Figure 2 shows a perspective view of the method of producing bare cell using enveloped separator method of the present .invention;

Figure 3 shows a perspective view of the method of producing bare cell using zig-zag method of the present invention;

Figure 4 shows a perspective view of the method of producing bare cell using winding method of the present invention;

Figure 5 shows a perspective view of the method of producing bare cell using flat jelly-roll method of the present invention;

Figure 6 shows a bus bar plate for positive and negative terminals of the present invention;

Figure 7· shows an illustration of the steps of connecting plates and performing ultrasonically spot welding process of the present invention;

Figure 8 shows a perspective view of an. integration of bare cell of the present invention; and

Figure 9 shows manufacturing process flow- of lithium ion battery to one embodiment of the present invention.

5. DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the figures, especially to Figure 1 and Figure 2, there are shown -the perspective view of a lithium-ion battery of the present invention. The lithium- ion battery (1). comprises of- among others, at least one bare cell (12), an anode plate (21), a cathode plate (22) alternatively arranged between a separators (23), bus bare plate (14) is provided with a plurality of slits (15) and welding plates (63). The electrochemical ^' cells can be formed^" via various methods either by enveloped separator, zig-zag, and winding or flat jelly roll. These structure except for the flatten jellyroll method uses a multi stacked electrode structure in which the anode and cathode electrode layer will have to be cut into the required size. and shape which are then stacked alternately proportional to the required capacity. A separator (23) is interposed between the anode electrode (21) and cathode electrode (22) forming bare cell (12) whereby repeatedly layering the positive electrode, the separator (23) and the negative electrode. Moreover, by calculating the capacity for one layer of the cell, the number of layer that heed to ^"be stacked to ^' build up a bare cell (12) can be determined easily. A plurality of these bare cells (12) can be stacked to prepare battery with practical^' capacity. The number of bare. cells (12) need to be stacked is proportional with the capacity required. For example, if^' the number of cells stacked is increasing thus the number of overlapping electrodes will also, be increasing. In this respect, by using the double side coating electrode for both anode and cathode, the thickness of the stacked electrode will decrease compared to the coating and using only a single side of the current collector.

In the embodiment of the present invention, the multiple bare cells (12) will be arranged having their respective anode (21) and cathode (22) layer overlapping each other. The alignment of the overlapped bare cell (12) will also be controlled. The bus bar plates (14) will be arranged at both right and left side of the tabs (25) and this bus bar plates (14), are preferably made of nickels (62) bus bar for the anode terminal because the nickel plates (62) are relatively lightweight for spot welding. On the other hand, aluminium (61) bus bar will .be used for the -cathode terminal. There are provided slits (15) in the^' same alignment and arranged at the middle of the^■ bus bar plate (14) . Each slits (14) has its welding plate (63) that can be bent upward to form a flat surface. The tabs (25) will be weld using ultrasonic spot welding method. The finished welded cells will be put in the suitable Teflon casing (11)^'.

Referring again to Figure 2 where the figure · shows the method of producing bare^' cell' using enveloped separator method of the present invention. As shown in Figure 2(a), the anode electrode (21) and cathode electrode (22) will be cut into required dimension. Next, the cut electrode will have uncoated terminals; for. electron connection. Then, as shown in Figure 2(b) the electrode anode (21) will be encapsulated (24) with separator enveloped (23) and electrode cathode- (22) will be left without encapsulated. Finally, as shown in Figure 2(c), the arrangement of the open tab terminal (25) of anode electrodes (21) and cathode electrodes (22) is in respective sides.

Figure 3 and Figure 4 show perspective views of the method of producing bare cell (12) using zig-zag method and winding method of the present- invention. For the zig-zag and winding method as shown in Figure 3(a) and 4(a), both of this methods use the same anode electrode (21) , separator (23) and the cathode electrode (22)- which is sequentially arranged but in the different technique of folding the separator (23) . Instead of that, the arrangement of the- open tab (25) terminal of anode electrodes (21) and cathode, electrodes (22) are in opposite sides as shown in Figure 3(b) and 4 (b) . Then, the sandwich structure between anode electrodes (21) and _.cathode .electrodes ^' (22) are combined together using^' zig-zag method (31) and winding method (41) to fabricate the bare cell (12) as shown in Figure 3(c) and 4(c).

Figure 5 shows a perspective view of ^■ the method of producing bare cell (12) using flat jelly-roll method of the present invention. For this method as shown in Figure 5(a), the anode electrode (21) and cathode electrode (22) will be slit in the long piece according to required cell capacity. The cut electrode will lay sandwich between anode electrodes (21), separator (23) and cathode electrodes (22) and wound in core cylindrical shape (52) and'flatted in the piece shape as shown in Figure 5 (b) . Finally, the arrangement of ■ the open tab (25) terminal . of anode electrodes (21) and cathode electrodes (22) is positioned in the opposite sides of each other as shown in Figure 5 (c) . Instead of that, . Figure 5 (d) also shows^' that the arrangement of the open tab terminal of anodes electrodes (21) and^' cathodes electrodes (22) can be positioned side by sides of each other's.

Figures 6 and 7 shows the bus bar plate for positive and negative terminals where the connection of this plate is effected by performing ultrasonically ^' spot welding method of the present invention. Figure 6(a) shows that the bus bar plate (14), which is preferably made of aluminium (61) and. nickel (62), having slits (15) and welding plate (63) for connecting to the positive and negative terminal of the complete lithium-ion cell structure.. There are also slits (15) arranged in the same alignment at the middle of the bus bar plate (14). Each slit (15) has its welding plate (63) that can be bent upward to form a flat surface. The area of the slit (15) can be adjusted or changed according to the thickness and size of the tabs (25) which function as the electrode terminal, of the. bare cell (12) and generally proportional to the capacity demand of the battery. .If the thickness of the anode tab (21) or cathode tab (22) for each bare cell (12) increases, the area of the slit (15) will need to be increased too. The bus bar (14) ■ size is not fixed but may come in the various sizes depend on■ the manufacturing requirements of the battery. Besides that, this bus bar (14) must fit well on. the stacked cells ( 81) .^'· Referring to Figure 7(a), the tabs (25) will be weld on the welding plate (63) using ultrasonic, spot welder to connect the electrode structure to the terminal one by one. Preferably, the welding process will be done start from the bottom until the last bare cell (12) . All the parameter for the welding process needs to be appropriately controlled to avoid any. mistake. Firstly, the bus bar plate (14) will be put on the anode tab (21) of the bare cell (12) . Then, the extended anode tab (21) rested on the welding plate (63) will be weld using ultrasonic spot welder or other suitable welding techniques. After the welding process completed, ^■ the welded terminal will be bent^■ upward and forming the flat surface. Then the process will continue with another bare cell (12) until the last bare cell (12) . These bare cells (12) will be put overlapped and welded together one by one until it -ful-fils the capacity demand. Similarly, the bus bar plate (14) will also be put on the cathode terminal (22). .and welded together using the same ultrasonic spot welder or the likes. After the welding process completed., the welded terminal will be bent upward and forming the flat surface. In this respect, ultrasonic spot welding -is ' · typically ^' a technique that produces a strong, structural weld and lends itself to large parts, and parts with complicated geometry and hard-to-reach joining surfaces. Ultrasonic spot _. welder will be applied at the upper and bottom head of the welding plate. Another option is the ultrasonic spot welder also can be applied at the upper head of the welding plate (63) in order to bent upward the welding plate (63). Referring,■now to Figure 6(b), it shows that the bus bar plate ^'(14) is- without the welding plates (63). During this process, the tabs (25) of the bare cell (12) will be folded and welded onto the bus bar plate (14) using ultrasonic spot welder or the likes, to connect the electrode structure to the terminal. The next process is similar with the. bus bar (14) with the welding plate (63).

Figure 8 shows a perspective view . of an already assembled bare cell of the- present invention. The arrangement of multiple bare cells (81) in the proper alignment and put overlapped and the tabs (25) are welded on the respective^'' welding plate (63) Figure 6(a) and according to ^'■ the respective polarity to form connection for the production of lithium-ion battery (1) of the present invention. During cell assembly, any moisture contamination will give deleterious effect on the cell operation/ performance. Therefore, a strict control is needed during the cell's assembling process. Thus, the finished cells or completed cells will be drying in oven to eliminate any moisture before the cell will be enter into the dry room or glove box for el.ectrolyte filling.

Figure 9 shows manufacturing process flow of lithium battery according to one embodiment of the present invention. To fabricate lithium-ion battery, several steps need to follow. Starting from preparation of material until cell stac-king, the process would still be the same for the known as well as the _.present invention. In the present invention, there are some process compared to the previous process that are eliminated and removed such^' as packaging bag cutting, bag forming, two side sealing, vacuum sealing, degassing, cell sorting and - cell welding. After the common process where the cell stacking is completed, all the tabs will be welded to the respective ^' bus bar plate (14)^" according to the respective clarity. Then the finished welded cell will be put into^■ a suitable Teflon casing (11) before the injection of electrolyte. In this respect, Teflon casing (11) is the best option for leakage protection due to the usage^■ of electrolyte^' solution that needs a rigid casing. Teflon is a thermoplastic^' synthetic material which maintains a unique character due to the special properties of its composition. Next is electrolyte dispensing. The electrolyte is typically a mixture of organic carbonates such as ethylene carbonate or diethyl carbonate containing complexes of lithium ions. These nonaqueous electrolytes generally use non-coordinating anion salts such as lithium hexafluorophosphate (LiPF₆) . The liquid electrolyte will be injected during packing. Final stage of producing lithium ion battery is to activate the cell. At the end of line, cell conditioning is carried out using cell^' cycler. Cell cycler .(not shown) will charge and discharge in a specific number of cycles. Depending from the specifications of the battery module, it is ^'become possible to freely adjust the capacity and power via serialization or parallelization. Battery Management System (BMS) , could also be is connected to a module cycler for module conditioning process. Moreover, the Battery ^■ Management System (BMS) is an electronic system that manages a rechargeable battery (cell or battery pack) , such as ^' by monitoring its state, calculating secondary data, reporting that data, protecting the battery, controlling its environment, and / or balancing it.

Still referring . to Figure 9, the present invention having the . following advantages:

1. Offering wide variety of shapes and sizes efficiently fitting the devices they intended to power.

2. Much lighter than other energy-equivalent secondary battery.

3. High open circuit voltage in comparison to aqueous

battery (such as lead acid, nickel-metal hydride and nickel-cadmium) . This is beneficial because it

increases the amount of power that can be transferred at a lower current. .

4. No memory effect.

5. Self-discharge rate of approximately 5-10% per month, compared to oyer 30% per month in common nickel metal hydride batteries, approximately 1.25% per month for Low Self-Discharge. NiMH^' batteries and 10% per month in nickel-cadmium batteries. .

6. Components are environmentally safe as there is no free lithium metal .

It is envisaged that feature of the present invention could be implemented^■ to replace the existing lithium-ion battery or can be used in a new- lithium-ion battery fabrication. While^■ the preferred embodiments of the present invention have been described, it should be understood that various- changes, adaptations and modifications may be made thereto. It should be understood, .therefore, that the invention is not limited to details of the illustrated invention shown in the figures arid that variations in such minor details will be apparent to one skilled in the art.

Claims

WHA.T IS CLAIMED IS:

1. A lithium-ion. battery (1) assembled within a casing

(11)^', said lithium-ion battery (1) comprising: at least one bare cell (12) , each of said bare cell

(12) ^· comprises of at least an anode -plate and cathode plate alternatively arranged between a separator ; and a connector (13) means connecting each of said anodes and cathode plates together in accordance to their respective polarity; characterized in that, said connector means (13) is ^' formed as a pair of bus bar plates (14)- where the bus bar plates (14) are arranged along the edge of said bare cell (12) and said bus bar plate is provided with a plurality of slits (15) .

2. A lithium-ion battery as claimed in Claim 1, further characterized in that a welding plate (63) is arranged to extend from each of said slit (15) .

3. A lithium-ion battery as claimed in Claim 1, further characterized in that each of said anode plates and cathode plates is provided with^' a tab (25) disposed at the edge. of the plate for allowing connection with said bus bar plates (14), wherein the tabs (25) having similar polarity are arranged together forming a stack of said similar polarity tabs (25) along the edge of bare cells (12) while tabs (25) having another similar polarity are arranged together forming another stack of similar polarity tabs (25) along the edge of' said bare cell (12) .

A lithium-ion battery as claimed in Claim 3, further characterized in that each of said tabs (25) is inserted into the respective slit (15) and welded together .

A lithium-ion battery as claimed in Claim 4, further characterized in that each of said tabs (25) is inserted into the respective slit (15) and welded together on said welding plate (22) .

A lithium-ion battery as claimed in Claim 5, further characterized in that said welding plates (63) are bent upward to form a flat surface^' to _. enclose said tabs (25).

A lithium-ion battery as claimed in any of the preceding claims,^' further characterized in that said bus bar plates (14) ^' are made of aluminum (61) and nickel (62) where the aluminum bus bar plate (61) is for connection to the cathode plates and the nickel bus bar (62) is for connection to the anode plates.

. A lithium-ion . battery as claimed in Claim. 5, further characterized in that said bus bar plates (14) are formed in various sizes^' according- to the desired capacity of the lithium ion battery.

A method of fabricating a lithium-ion battery comprising the steps of; a) preparing a bare- cell (12) that comprises of at least an anode, plate and cathode plate alternatively^" arranged between a separator (23) ; b) arranging at least one of said bare cell (12) to form one or multi-stack of bare cells (81); c) positioning a connector means (13) to connect each of said anode and cathode plates together in accordance to their respective polarity; characterized in that, said connector means (13) is formed as a pair of bus bar plates (14) where the bus plates (14) is each positioned along the edge of said bare cell (12) and said bus bar plate (14) is provided with a- plurality of slits (15), and each of said anode plates and cathode plates is provided with a tab (25) disposed at the edge of the plate and the tabs having similar polarity are arranged together to form another stack of similar polarity tabs (25) _^ along the edge of the bare cells (12) while . tabs having another similar polarity are arranged together to form another stack of similar .polarity tabs (25) along the edge of said bare cells; and

'inserting said tabs (25) into the respective ■5 slit (15) of said bus. bar plate (14) and welding said tabs (25) to said bus bar plate (14)..

10. A method of fabricating a lithium-ion battery as claimed in Claim 9, further characterized in that said tabs (25) are welded onto said welding plate (22) by

10 performing ultrasonic spot welding, laser welding or the likes.

11. A method of fabricating a lithium-ion battery as claimed in Claim 10, further characterized in that said assembled lithium-ion battery including the connected

15 bus bar plates (14) are put into a casing (11) for final packaging.-

12. A method of fabricating a lithium-ion battery as claimed in Claim 11, further characterized in that an electrolyte is dispense into said assembled casing

20 . . · (11) .

13. A method of fabricating a lithium-ion battery as claimed in any of Claims 9 to 12, further characterized n that said bus bar plates (14) are configured according to the number of bare cells (12) which

25 further configured according to the desired battery' s capacity. A method of fabricating a lithium-ion battery as claimed in Claim 13, further characterized in that said multi-stack of bare cells (81) are prepared according to Enveloped Separator- Method^", Zig-zag Method, Winding Method or Flatten Jellyroll Method of bare cell - methods of fabrication.