Patent Application
20160204392
The present invention relates to a method of manufacturing a prismatic battery cell. More particularly, the present invention relates to a method of manufacturing a battery cell including an electrode assembly, which includes a separator interposed between a cathode and an anode and is sealed inside a prismatic battery case, including bending and then welding a metal plate having a predetermined thickness to manufacture a prismatic body in which the upper portion and bottom portion are open, manufacturing upper and bottom portion sealing members corresponding to shape of each of the upper portion and bottom portion of the prismatic body, contacting and then welding the bottom portion of the prismatic body and the bottom portion sealing member, inserting the electrode assembly into the battery case, the bottom portion of which is sealed, and contacting and then welding the upper portion of the battery case and the upper portion sealing member.
Recently, people are more concerned with environmental problems and depletion of natural sources and, as such, interest in solar cells as an alternative energy source which does not cause environmental pollution is growing. Solar cells are classified into silicon solar cells, thin film-type compound solar cells, layered-type solar cells and the like. Among these solar cells, silicon semiconductor solar cells are the most widely studied.
An electrode assembly may be configured to have a jelly-roll (wound) type structure in which a long sheet type cathode and a long sheet type anode are wound while a separator is disposed between the cathode and the anode, a stacked type structure in which pluralities of cathodes and anodes having a predetermined size are sequentially stacked while separators are disposed respectively between the cathodes and the anodes, or a stacked/folded type structure in which pluralities of cathodes and anodes having a predetermined size are sequentially stacked while separators are disposed respectively between the cathodes and the anodes to constitute a bi-cell or a full-cell and then a plurality of bi-cells or full-cells is folded, according to the structure of an electrode assembly having a cathode/separator/anode structure.
In addition, secondary batteries are classified into a cylindrical or prismatic battery including an electrode assembly in a cylindrical or rectangular metal can and a pouch type battery including an electrode assembly in a pouch type case made of an aluminum laminate sheet according to shapes of battery cases.
Especially, prismatic batteries having relatively narrow width, according to miniaturization and weight reduction trends of mobile electric devices, have been developed. Such prismatic batteries may be applied to different applications than cylindrical type batteries.
Generally, prismatic batteries are manufactured by welding an upper portion cap assembly and injecting an electrolyte thereinto and then sealing an injection port after inserting some battery members into a prismatic hollow case, a bottom portion of which is sealed. Here, the prismatic hollow case having the sealed bottom portion is generally manufactured by processing an aluminum alloy plate according to a deep drawing method as exemplified in
Since a plate may be manufactured into a final hollow case through continuous deep drawing processes, the deep drawing method has high efficiency. However, the deep drawing method has some drawbacks as follows.
First, since a process of the deep drawing method consists of, approximately, 10 steps or more, and is sophisticated, manufacturing costs related thereto are extremely high. Especially, to manufacture a mold or the like, a long period of 2 to 3 months is generally required and thereby required time to develop batteries in accord with changing tastes of consumers greatly is greatly extended.
Second, materials able to be processed according to the deep drawing method are extremely limited. During the deep drawing process, materials are stretched and, as such, only materials capable of undergoing stretching can be user. However, it is generally difficult to stretch materials having high intensity and, as such, it may be difficult to obtain battery cases having desired characteristics.
Finally, when prismatic battery cases are processed according to a deep drawing method and a thickness ratio of a long side and short side of a bottom portion exceeds a predetermined ratio, edge cracks may occur and, as such, an error rate of products is high and case dimensions are limited.
Therefore, there is an urgent need to develop a technology that can fundamentally address these problems.
The present invention aims to address the aforementioned problems of the related art and to achieve technical goals that have long been sought.
Namely, the present invention aims to provide a method of manufacturing a prismatic battery cell, production cost of which is reduced due to a simplified manufacturing process and improved production process efficiency, by constituting a battery case such that a prismatic body having an open upper portion and bottom portion by bending and then welding a metal plate having a predetermined thickness, and an upper and bottom portion sealing member corresponding to shape of each of the upper portion and bottom portion of the prismatic body are combined.
The present invention also aims to provide a method of easily manufacturing a prismatic battery cell while improving a production ratio and obtaining high yield.
In accordance with one aspect of the present invention, provided is a method of manufacturing a battery cell including an electrode assembly which includes a separator interposed between a cathode and an anode, and is sealed inside a prismatic battery case, the method including:
(a) bending and then welding a metal plate having a predetermined thickness to manufacture a prismatic body in which an upper portion and bottom portion are open;
(b) manufacturing upper and bottom portion sealing members corresponding to shape of each of an upper portion and a bottom portion of a prismatic body;
(c) contacting and then welding the bottom portion of the prismatic body and the bottom portion sealing member;
(d) inserting the electrode assembly into the battery case, the bottom portion of which is sealed, manufactured according to step (c); and
(e) contacting and then welding the upper portion of the battery case and the upper portion sealing member manufactured according to step (d).
Therefore, a manufacturing cost of the method of manufacturing the battery cell according to the present invention may be reduced by combining together segmented case members, when compared to a deep drawing method. In addition, the total manufacturing period of the battery cell may be greatly shortened. Further, the battery cell may be manufactured in a variety of designs and, at the same time, the error rates of products may be reduced.
In one embodiment, overlapped both end portions of the metal plate bent according to step (a) may be welded in a state that sections of the end portions contact. In this case, as desired, the bent metal plate may be welded in a state that the overlapped both end portions are overlapped to a predetermined width.
In particular, a width by which both end portions overlap may be in a range of 0.1 to 10 mm. The overlapped portion may be welded after rolling such that the thickness of the overlapped portion is 110% to 150% based on the thickness of the metal plate.
Such a method of welding a case member is not limited specifically so long as the case member may be combined with high intensity and sealed. For example, the welding method may be a laser welding method, arc welding method, electric resistance welding method, gas welding method, ultrasonic welding method, or the like. Among these welding methods, the laser welding method may be more preferable.
Materials of a metal plate and sealing member constituting the prismatic battery cell according to the present invention are not specifically limited so long as the materials have properties suitable for a battery case, may be manufactured to a plate type and may be used in a manufacturing process of a cell case. The materials may be, concretely, aluminum or an aluminum alloy.
In addition, the battery case has a predetermined thickness. For example, the battery case may have a thickness of 0.1 to 1 mm. When the battery case is too thick, the total thickness or volume of a final battery cell product may be enlarged. On the contrary, when the battery case is too thin, the battery case may not have desired mechanical intensity and the prismatic battery cell may not be protected against external shock. Therefore, the battery case having thickness outside the above range is not preferable.
The upper portion sealing member and bottom portion sealing member may be manufactured, for example, by a forging, blanking or cutting process. The upper portion sealing member may include an electrolyte injection port for electrolyte injection.
Meanwhile, lithium secondary batteries go through a formation process during manufacture of the lithium secondary battery. The formation process is a process of charging and discharging the lithium secondary batteries after assembly of the lithium secondary batteries to activate the lithium secondary batteries. During charging of the lithium secondary batteries, lithium ions discharged from a cathode of the lithium secondary battery migrate to a carbon electrode, which is used as an anode of the lithium secondary batteries. At this time, a solid electrolyte interface (SEI) film is formed at the surface of the anode.
In the formation process, the lithium secondary batteries are repeatedly charged and discharged with constant current or constant voltage in a predetermined range. To effectively perform the activation process of the battery cell, at least a portion of outer surfaces of the battery case is coated with an insulative material.
The insulative material is not specifically restricted so long as the insulative material is coated on the outer surface of the prismatic can to insulate the outer surface of the prismatic can from the outside. For example, the coating of the prismatic can with the insulative material may be achieved by anodizing an aluminum oxide on the outer surface of the prismatic can, by spraying the insulative material to the outer surface of the prismatic can, or by spreading an insulative thin film label to the outer surface of the prismatic can.
The electrode assembly, which is not particularly limited, is preferably a folding type electrode assembly, stack type electrode assembly and stack/folding type electrode assembly. In one embodiment, taps extended from an electrode assembly are combined with one electrode lead. Due to the electrode lead, a planar type electrode terminal is formed.
Korean Patent Application Pub. Nos. 2001-0082058, 2001-0082059 and 2001-0082060 particularly disclose with respect to the stack/folding type electrode assembly. The applications are combined as references of the present invention.
The battery pack according to the present invention may be applied to a lithium ion secondary battery in which an electrode assembly is impregnated with a lithium-containing electrolyte, a lithium ion polymer battery in which an electrode assembly is impregnated with a gel-type lithium-containing electrolyte, and the like
In general, a lithium secondary battery includes a cathode, an anode, a separator, and a lithium salt-containing non-aqueous electrolyte.
The cathode may be manufactured by, for example, coating a mixture of a cathode active material, a conductive agent, and a binder on a cathode current collector and drying the coated cathode current collector. The mixture may further include a filler as desired.
Examples of the cathode active material include, without being limited to, layered compounds such as lithium cobalt oxide (LiCoO2) and lithium nickel oxide (LiNiO2) or compounds substituted with one or more transition metals; lithium manganese oxides represented by Li1-xMn2-xO4 where 0≦x≦0.33, such as LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, and Cu2V2O7; Ni-site type lithium nickel oxides having the formula LiNi1-xMxO2 where M═Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and 0.01≦x≦0.3; lithium manganese composite oxides having the formula LiMn2-xMxO2 where M═Co, Ni, Fe, Cr, Zn, or Ta, and 0.01≦x≦0.1 or the formula Li2Mn3MO8 where M═Fe, Co, Ni, Cu, or Zn; LiMn2O4 where some of the Li atoms are substituted with alkaline earth metal ions; disulfide compounds; and Fe2(MoO4)3.
The conductive material is typically added in an amount of 1 to 30 wt % based on a total weight of a mixture including a cathode active material. There is no particular limit as to the conductive material, so long as it does not cause chemical changes in the fabricated battery and has conductivity. Examples of conductive materials include, but are not limited to, graphite such as natural or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metallic fibers; metallic powders such as carbon fluoride powder, aluminum powder, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives.
The binder is a component assisting in binding between an active material and a conductive material and in binding of the active material to a current collector. The binder may be typically added in an amount of 1 to 50 wt % based on a total weight of a mixture including a cathode active material. Examples of the binder include, but are not limited to, polyvinylidene fluoride, polyvinyl alcohols, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluorine rubber, and various copolymers.
The filler is optionally used as a component to inhibit cathode expansion. The filler is not particularly limited so long as it is a fibrous material that does not cause chemical changes in the fabricated secondary battery. Examples of the filler include olefin-based polymers such as polyethylene and polypropylene; and fibrous materials such as glass fiber and carbon fiber.
The anode is manufactured by coating and drying an anode active material on an anode current collector. In this case, as desired, the ingredients described above may be further selectively included.
Examples of the anode active material include, for example, carbon such as hard carbon and graphite-based carbon; metal composite oxides such as LixFe2O3 where 0≦x≦1, LixWO2 where 0≦x≦1, SnxMe1-xMe′yOz where Me: Mn, Fe, Pb, or Ge; Me′: Al, B, P, Si, Group I, II and III elements, or halogens; 0≦x≦1; 1≦y≦3; and 1≦z≦8; lithium metals; lithium alloys; silicon-based alloys; tin-based alloys; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5; conductive polymers such as polyacetylene; and Li—Co—Ni-based materials.
The separator is disposed between the cathode and the anode and, as the separator, a thin insulating film with high ion permeability and high mechanical strength is used. The separator generally has a pore diameter of 0.01 to 10 μm and a thickness of 5 to 300 μm. As the separator, for example, sheets or non-woven fabrics, made of an olefin polymer such as polypropylene; or glass fibers or polyethylene, which have chemical resistance and hydrophobicity, are used. When a solid electrolyte such as a polymer or the like is used as an electrolyte, the solid electrolyte may also serve as a separator.
The lithium salt-containing non-aqueous electrolyte consists of a polar organic electrolyte and a lithium salt. The electrolyte may be a non-aqueous liquid electrolyte, an organic solid electrolyte, an inorganic solid electrolyte, or the like.
Examples of the non-aqueous liquid electrolyte include non-protic organic solvents such as N-methyl-2-pyrollidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxy ethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxy methane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ether, methyl propionate, and ethyl propionate.
Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphoric acid ester polymers, poly agitation lysine, polyester sulfide, polyvinyl alcohols, polyvinylidene fluoride, and polymers containing ionic dissociation groups.
Examples of the inorganic solid electrolyte include, without being limited to, nitrides, halides and sulfates of lithium (Li) such as Li3N, LiI, Li5NI2, Li3N—LiI—LiOH, LiSiO4, LiSiO4—LiI—LiOH, Li2SiS3, Li4SiO4, Li4SiO4—LiI—LiOH, and Li3PO4—Li2S—SiS2.
The lithium salt is a material that is readily soluble in the non-aqueous electrolyte and examples thereof include, without being limited to, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB10Ch10, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (CF3SO2)2NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate, and imides.
In addition, in order to improve charge/discharge characteristics and flame retardancy, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphoric triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxy ethanol, aluminum trichloride or the like may be added to the non-aqueous electrolyte. If necessary, in order to impart incombustibility, the non-aqueous electrolyte may further include halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride. Further, in order to improve high-temperature storage characteristics, the non-aqueous electrolyte may further include carbon dioxide gas.
The present invention also provides a battery cell manufactured according to the above method.
In addition, the present invention provides a battery pack including at least one prismatic battery cell and a device using the battery pack as a power supply. The device may be, concretely, laptop computers, cellular phones, PDPs, PMPs, MP3 players, digital still cameras (DSCs), DVRs, smart phones, GPS systems, camcorders, electric vehicles, hybrid electric vehicles, and plug-in hybrid electric vehicles, power storage devices, and the like.
The structures and manufacturing methods of battery packs and devices are known publicly in the art. Therefore, detailed descriptions of the structures and manufacturing methods are omitted.
As is apparent from the above description, by using a method of manufacturing the prismatic battery cell according to the present invention, a battery case is constituted such that an upper and bottom portion sealing member corresponding to the shape of each of an upper portion and bottom portion of a prismatic body, which has an upper and bottom portion which are open by bending and then welding a metal plate of a predetermined thickness, are combined each other. Consequently, a manufacturing method of the prismatic battery cell is simplified and production process efficiency is improved and, accordingly, manufacturing costs are reduced and a prismatic battery cell which was not manufactured using a deep drawing method may be manufactured.
The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawing, in which:
Now, the present invention will be described in more detail with reference to the following examples. These examples are provided only for illustration of the present invention and should not be construed as limiting the scope and spirit of the present invention.
Referring to
A prismatic body 120 having an upper portion and bottom portion which are opened by bending and then welding a metal plate having a predetermined thickness, an upper portion sealing member 130 and bottom portion sealing member 140 corresponding to the shape of each of the upper portion and bottom portion of the prismatic body 120 are respectively manufactured. After inserting the electrode assembly 110 into the battery case, the upper portion sealing member 130 and the bottom portion sealing member 140 contact with the prismatic body 120 and then are welded, resulting in completion of fabrication of a prismatic battery cell 100.
The prismatic battery cell 100 having such a structure includes a welding side 150 in which end portions of a metal plate at one side of the prismatic battery cell 100 are welded since the prismatic body 120 constituting the prismatic battery cell 100 is manufactured by bending and then welding a metal plate.
First, a metal plate 210 which is made of aluminum alloy and has a thickness of, approximately, 0.3 mm, is bent in the shape of the battery case as illustrated in
Alternatively, as illustrated in
As illustrated in
Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2013-0106641 | Sep 2013 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2014/006379 | 7/15/2014 | WO | 00 |
