KR101243445B1 - Lithium rechargeable battery - Google Patents

Abstract

The present invention relates to a lithium secondary battery, and more particularly, in the formation of an electrode assembly, an ultra-thin large-area electrode plate is provided by not winding or multiplying an electrode plate, but having dimensions optimized for mounting in a notebook computer or the like. It relates to a lithium secondary battery.

Lithium Secondary Battery, Pouch Type, Ultra Thin, Large Area, Polymer

Description

Lithium rechargeable battery

1 is an exploded perspective view of a lithium secondary battery according to an embodiment of the present invention.

2A is a coupling diagram of a first electrode plate and a second electrode plate according to an embodiment of the present invention;

Figure 2b is a vertical cross-sectional view of the electrode assembly according to an embodiment of the present invention

Figure 3a is a coupling diagram of the positive electrode plate and the negative electrode plate according to another embodiment of the present invention

Figure 3b is a vertical cross-sectional view of the electrode assembly according to another embodiment of the present invention

Description of the Related Art

100-Lithium Secondary Battery 150-Top Case

160-Lower Case 162-Space

164-Enclosure 180-Case

200-electrode assembly 202, 222-first electrode plate (cathode plate)

204, 224-Cathode collector 206, 226-Cathode active material layer

208, 218-Cathode plain part 210-Separator

212, 232-Second electrode plate (anode plate) 214, 234-Positive electrode current collector

216, 236-Cathode active material layer 220-Cathode tab

228-Positive electrode blank 240-Positive electrode tab

The present invention relates to a lithium secondary battery, and more particularly, in the formation of an electrode assembly, an ultra-thin large-area electrode plate is provided by not winding or multiplying an electrode plate, but having dimensions optimized for mounting in a notebook computer or the like. It relates to a lithium secondary battery.

As the weight reduction and high functionalization of portable wireless device products such as video cameras, mobile phones, notebook computers, portable personal digital assistants (PDAs), and power tools have increased, the importance of batteries used as driving power for these products has increased. Much research has been done on.

In particular, lithium secondary batteries capable of charging and discharging have a higher energy density per unit weight and rapid charge than conventional lead acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries due to the light characteristics of lithium atoms. Since this is possible, research and development on this is being actively conducted.

Lithium secondary batteries use nonaqueous electrolytes because of their reactivity with lithium. This electrolyte may be a solid polymer containing lithium salts, or may be a liquid phase in which lithium salts dissociate in an organic solvent. Solutions in which lithium salts dissolve are usually ethylene carbonate, propylene carbonate or other alkyl group-containing carbonates or similar organic compounds, having boiling points above 50 ° C. and very low vapor pressures at room temperature. Lithium secondary batteries may be classified into lithium metal batteries using a liquid electrolyte, lithium ion batteries, and lithium ion polymer batteries using a polymer solid electrolyte according to electrolyte types. Lithium ion polymer battery is a lithium ion polymer battery using an all solid lithium ion polymer battery which does not contain any organic electrolyte solution depending on the type of polymer solid electrolyte, and a gel polymer electrolyte containing organic electrolyte solution. Can be divided.

In the case of a completely solid lithium ion polymer battery, there is no problem of leakage of the organic electrolyte, and in the case of a gel type lithium ion polymer battery containing the organic electrolyte, a problem of leakage of the organic electrolyte may occur. However, as compared with lithium ion batteries using a liquid electrolyte, the problem of leakage of electrolyte in the case of lithium ion polymer batteries can be prevented in a simpler form. For example, a lithium ion polymer battery may use a multilayer film pouch consisting of a metal foil and one or more polymer films covering the foil, instead of a metal can of a lithium ion battery. The use of a multilayer film pouch has the advantage of significantly reducing the weight of the battery than using a metal can. Aluminum is usually used as the metal forming the foil in the multilayer film pouch. The polymer film forming the inner layer of the pouch film protects the metal foil from the electrolyte and prevents short circuit between the positive electrode, the negative electrode, and the electrode tabs.

As an example of how to form the pouch, first, the edges of the three sides except one side formed by the folded portion of the pouch film are folded in the middle of the upper and lower portions of the pouch by folding the middle of the pouch film. To achieve. The lower portion is formed with a groove that can accommodate the battery cell through a press (press) process or the like. Stacked electrode assemblies in which a plurality of separated electrode plates are stacked to draw electrode tabs from each electrode plate and then welded to each electrode tab may be used, but in general, a multilayer film laminated in the order of a positive electrode plate, a separator, and a negative electrode plate in a vortex shape is used. It is wound up to form a jelly roll. When forming the jelly roll, a separator is added to the electrode surface exposed to the outside of the roll to prevent a short circuit between the positive electrode and the negative electrode. The formed jelly roll is placed in the lower groove of the pouch film. The upper and lower portions of the pouch film are sealed by heating and pressing in a state in which the upper and lower portions of the four sides around the lower grooves are in close contact.

However, in the case of the multi-layered or wound type as described above, the size of the battery that can be developed and mass produced at the current level is limited. In order to use a battery of a larger size, a plurality of batteries can be used as a pack battery by connecting them in series or in parallel. There is no choice but to. In this case, an additional process and a unit cost are required for the configuration of the electric circuit and the pack battery, and there is a problem that the total volume of the battery is significantly increased.

The present invention has been made to solve the above problems, in particular, in the formation of the electrode assembly is provided with an ultra-thin large area electrode plate by not winding or multi-layered electrode plate, dimensions optimized for mounting on a notebook computer, etc. It is an object to provide a lithium secondary battery having a.

The lithium secondary battery according to the present invention for achieving the above object is inserted into the first electrode plate and the inner surface of the first electrode plate folded to form a V-shaped cross-section and the opposite polarity of the first electrode plate An electrode assembly having a second electrode plate having a separator and a separator interposed between the first electrode plate and the second electrode plate; And a case accommodating the electrode assembly, the thickness of which is less than 5% of the width.

In addition, the electrode assembly may be formed in a rectangular shape or a square shape.

In addition, the width of the lithium secondary battery may be at least 100mm. In addition, the thickness of the lithium secondary battery may be made of 2 ~ 5mm. In addition, the thickness of the lithium secondary battery may be less than 5.6% of the total height. In addition, the lithium secondary battery may have a total height of at least 90 mm.

In addition, the first electrode plate may be a negative electrode plate, and the second electrode plate may be a positive electrode plate.

In addition, the lithium secondary battery according to another aspect of the present invention, the first electrode plate is folded in the V-shape, the electrode plate is folded in the V-shape, but is arranged to face the V-shaped and the open portion of the first electrode plate and the first electrode plate An electrode assembly having a second electrode plate which is formed to be engaged with each other so as to be alternately stacked with the first electrode plate, and having a polarity opposite to that of the first electrode plate, and a separator interposed between the first electrode plate and the second electrode plate; It includes a case for accommodating the electrode assembly, characterized in that the thickness is made 5% or less of the width.

In addition, the lithium secondary battery may be formed in any one of the shapes mentioned above.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, a lithium secondary battery according to an embodiment of the present invention will be described.

1 is an exploded perspective view of a lithium secondary battery according to an embodiment of the present invention. FIG. 2A illustrates a coupling between the first electrode plate and the second electrode plate according to an embodiment of the present invention, and FIG. 2B illustrates a vertical cross-sectional view of the electrode assembly according to the embodiment of the present invention.

Referring to FIG. 1, a lithium secondary battery 100 according to an embodiment of the present invention is formed to include an electrode assembly 200 and a pouch-type case 180 accommodating the electrode assembly 200. The electrode assembly 200 includes a first electrode tab 220 and a second electrode tab 240, and the first electrode tab 220 and the second electrode tab 240 extend outside the case 180. It is formed to be drawn out. Hereinafter, a description will be given that the first electrode is a cathode and the second electrode is an anode. Of course, the first electrode may be an anode and the second electrode may be a cathode according to the design of the battery. In the case of the gel lithium secondary battery, the electrolyte is injected into the case through an electrolyte injection hole (not shown), and the case is sealed after the electrolyte is injected. In the case of an all-solid-type lithium secondary battery, since a semiconductor-type polymer electrolyte is formed on a flexible polymer material, such as a polyethylene (PE) separator, it can operate as a lithium secondary battery without injecting a separate electrolyte. Do.

The lithium secondary battery 100 may have a thickness less than or equal to 5% of the width. Table 1 shows representative ones as a standard of the lithium secondary battery 100. These standards are data derived by experiments, and the present invention is not limited to these standards because they are presented as embodiments of the present invention.

Thickness T (mm) Width W (mm) Total Height H (mm) T / W (%) T / H (%) 5 100 90 5.0 5.6 5 150 130 3.3 3.8 5 200 150 2.5 3.3 5 250 190 2.0 2.6 5 300 220 1.7 2.3 4 100 90 4.0 4.4 4 150 130 2.7 3.1 4 200 150 2.0 2.7 4 250 190 1.6 2.1 4 300 220 1.3 1.8

(Continued Table 1)

Thickness T (mm) Width W (mm) Total Height H (mm) T / W (%) T / H (%) 3 100 90 3.0 3.3 3 150 130 2.0 2.3 3 200 150 1.5 2.0 3 250 190 1.2 1.6 3 300 220 1.0 1.4 2 100 90 2.0 2.2 2 150 130 1.3 1.5 2 200 150 1.0 1.3 2 250 190 0.8 1.1 2 300 220 0.7 0.9

Referring to Table 1, the thickness (T) may be formed to be 5% or less of the width (W). If the thickness is too thick, the heat generation inside the battery increases, which makes it difficult to dissipate the heat sufficiently to the outside of the battery.In addition, the internal resistance varies depending on the part of the battery due to a large temperature difference between the inside of the battery and the surface of the battery. Therefore, there is a problem that the voltage imbalance increases. In addition, referring to Table 1, the thickness may be formed to be 5.6% or less of the total height. The reason is similar to that mentioned above for the relationship between thickness and width. In addition, the width W of the lithium secondary battery 100 may be at least 100 mm, and the total height H may be at least 90 mm. Accordingly, the thickness is preferably made of 2 to 5 mm. This is set to a value suitable for realizing a large area battery of a wide range, such as for notebook computers. Due to the nature of the notebook computer, the width and height may be large, but the thickness should be as thin as possible. Therefore, the thickness is reduced as much as possible, but the width and the gross height are formed as large as possible to secure the capacity. However, the use of the lithium secondary battery 100 is not limited to a notebook computer, and the width, the total height, and the thickness are only examples, and thus may be changed depending on the use and design.

The case 180 is formed of a multilayer film pouch composed of a metal foil and at least one polymer film covering the metal foil. The case 180 includes an upper case 150 and a lower case 160 coupled with the upper case 150. The outer shape of the combined upper case 150 and the lower case 160 is formed to correspond to the outer shape of the electrode assembly 200 in order to minimize the volume. The case 180 may be formed in a rectangle, a square, or the like, but the shape of the case 180 is not limited thereto. At least one side of the upper and lower cases 150 and 160 are integrally in contact with each other, and the other sides are open to each other. The lower case 160 has a space 162 in which the electrode assembly 200 is accommodated, and a sealing surface 164 is formed along an edge of the space 162. The sealing surface 164 is a portion in which the electrode assembly 200 is accommodated in the space 162 and then sealed by heat fusion.

Referring to FIGS. 2A and 2B, the electrode assembly 200 includes a negative electrode plate 202, a positive electrode plate 212, and a separator 210 interposed between the negative electrode plate 202 and the positive electrode plate 212. do. The electrode assembly 200 may be formed in a rectangular or square shape, but the electrode assembly 200 is not limited to the shape of the electrode assembly 200.

The negative electrode plate 202 includes a negative electrode current collector 204 made of a metal thin plate, and a negative electrode active material layer 206 coated on one surface of the negative electrode current collector 204. The negative electrode current collector 204 is preferably a copper foil, which is a metal thin plate having excellent conductivity, and the negative electrode active material layer 206 is a composition in which a binder, a plasticizer, a conductive material, and the like are mixed with a negative electrode active material such as a carbon material. . In addition, the negative electrode non-coating portion 208, which is a portion of the negative electrode current collector 204, in which the negative electrode plate 202 is folded, does not have the negative electrode active material layer 206. The reason why the negative electrode non-coating portion 208 is formed in the portion where the negative electrode plate 202 is folded is that when the negative plate 202 is folded, the negative electrode active material layer 206 existing on the inner side of the folded portion may be detached. This is because the folded portion does not face the positive electrode active material layer 216. A negative electrode tab 220 is attached to the negative electrode plate 202, and a protective tape having a predetermined width may be wound on an outer surface of the end side of the negative electrode tab 220.

The positive electrode plate 212 includes a positive electrode current collector 214 made of a metal thin plate and a positive electrode active material layer 216 coated on both surfaces of the positive electrode current collector 214. The positive electrode current collector 214 is preferably an aluminum thin plate having excellent conductivity, and the positive electrode active material layer 216 is a composition in which a lithium oxide is mixed with a binder, a plasticizer, a conductive material, and the like. A positive electrode tab 240 may be attached to the positive electrode plate 212, and a protective tape having a predetermined width may be wound on an outer surface of an end side of the positive electrode tab 240.

The separator 210 may be interposed between the negative electrode plate 202 and the positive electrode plate 212 and extend to surround the outer circumferential surface of the electrode assembly 200. The separator 210 is formed of a porous membrane polymer material to prevent short circuit between the negative electrode plate 202 and the positive electrode plate 212 and to allow lithium ions to pass therethrough.

Referring to FIG. 2A, the negative electrode plate 202 is folded in a V-shape, and the positive electrode plate 212 is inserted into an inner surface of the negative electrode plate 202. That is, the positive electrode plate 212 is inserted into the open portion of the V-shaped negative electrode plate 202. The negative electrode plate 202 is preferably formed on the inner side of the V-shape, that is, the portion facing the positive electrode plate 212, and the negative electrode non-coating portion 208 is formed on the remaining portion.

Thus, by forming the positive electrode plate and the negative electrode plate, it is possible to form a large area electrode assembly that is not possible in the conventional wound or stacked electrode assembly. That is, according to the present invention, it is possible to form an ultra-thin electrode assembly, which is a structure suitable for application to an electronic product in which the thickness of a battery such as a notebook computer needs to be thin.

The electrode assembly 200 is mounted to the lower case 160 provided with a space 162. At this time, ends of the negative electrode tab 220 and the positive electrode tab 240 electrically connected to the respective electrode plates 202 and 212 of the electrode assembly 200 are drawn out of the case 180 to be sealed. After the electrode assembly 200 is seated, the electrode assembly 200 is sealed by applying a predetermined heat and pressure to the sealing surface 164 formed along the edge of the space 162. At this time, the sealing surface 164 is a portion extending integrally from the case 180 along the edge of the space portion 162, and maintains a predetermined width.

Next, a lithium secondary battery according to another embodiment of the present invention will be described.

Figure 3a shows a coupling of the positive electrode plate and the negative electrode plate according to another embodiment of the present invention, Figure 3b is a vertical cross-sectional view of the electrode assembly according to another embodiment of the present invention. Since the embodiment of FIG. 3A is similar to the embodiment of FIG. 2A except that both the negative electrode plate 222 and the positive electrode plate 232 are folded and engaged with each other in a V-shape, the differences will be described.

Another electrode assembly according to another embodiment of the present invention, referring to Figure 3a, the negative electrode plate 222 is folded in the V-shape, the positive electrode plate 232 is also folded in the V-shape while the V of the negative electrode plate 222 The shape of the ruler and the open portions are disposed to face each other so that the negative electrode plate 222 and the positive electrode plate 232 are alternately stacked with each other. In this case, the negative electrode plate 222 is formed on two surfaces forming an inner surface and a surface of the outer surface which does not form an outer circumferential surface of the electrode assembly 200. In addition, the positive electrode plate 232, the positive electrode active material layer 236 is formed on a surface of the two inner and outer surfaces that do not form the outer peripheral surface of the electrode assembly 200. In addition, the separator 210 is interposed between the negative electrode active material layer 226 of the negative electrode plate 222 and the positive electrode active material layer 236 of the positive electrode plate 232.

The lithium secondary battery may have a thickness less than or equal to 5% of a width, and may be less than or equal to 5.6% of a total height. In addition, the width may be at least 100mm, the gross height is at least 90mm, the thickness is 2 ~ 5mm. In addition, the electrode assembly may have a rectangular shape or a square shape. In this manner, the lithium secondary battery may be implemented as a wide ultra-large-area battery, and both the positive electrode plate 222 and the negative electrode plate 232 may be formed to be engaged with each other in a folded V-shape, thereby increasing capacity.

As described above, the present invention is not limited to the above-described specific preferred embodiments, and any person skilled in the art may apply the present invention without departing from the gist of the present invention. It is to be understood that various changes and modifications may be practiced within the scope of the appended claims.

According to the lithium ion battery according to the present invention, a conventional wound or stacked electrode assembly solves the problem of not being able to manufacture a large area battery, and is used in the form of a pack battery for an electric / electronic product requiring a large capacity. Without this, the power can be stably supplied, and the configuration of the electric circuit and the battery pack are unnecessary due to the use of a plurality of batteries, thereby simplifying the process and reducing the manufacturing cost.

In addition, the present invention requires an ultra-thin battery, such as a notebook computer, but is applied to the electrical / electronic products that can be mounted in a large area, there is an effect that can reduce the volume occupied by the battery in the product.

In addition, the present invention is implemented so that the thickness is very thin compared to the width and total height to reduce the amount of heat generated inside the battery so that the heat generated is sufficiently radiated to the outside of the battery, the temperature difference between the inside of the battery and the surface of the battery is reduced, the internal resistance according to the site By making this uniform, there is an effect that the charge amount and voltage imbalance of the battery can be eliminated.

Claims (9)

A first electrode plate folded to form a V-shape, a second electrode plate inserted into an inner surface of the first electrode plate and having a polarity opposite to that of the first electrode plate, the first electrode plate and the second electrode plate; An electrode assembly having a separator interposed between the electrode plates; And It includes a case for receiving the electrode assembly, A lithium secondary battery, characterized in that the thickness is 5% or less of the width. The method of claim 1, The electrode assembly is a lithium secondary battery, characterized in that formed in a rectangular shape or a square shape. The method of claim 1, A lithium secondary battery, characterized in that the width of the lithium secondary battery made of at least 100mm. The method of claim 1, The lithium secondary battery has a thickness of 2 to 5mm, characterized in that the lithium secondary battery. The method of claim 1, The lithium secondary battery has a thickness of less than 5.6% of the total thickness of the lithium secondary battery. The method of claim 1, The lithium secondary battery is a lithium secondary battery, characterized in that the gross height is at least 90mm. The method of claim 1, The first electrode plate is a negative electrode plate, the second electrode plate is a lithium secondary battery, characterized in that the positive electrode plate. The electrode plate is folded in a V shape and the first electrode plate is folded in a V shape and arranged to face each other so that the V-shaped shape and the open portions of the first electrode plate face each other and are alternately stacked with the first electrode plate. An electrode assembly including a second electrode plate having a polarity opposite to that of the first electrode plate, and a separator interposed between the first electrode plate and the second electrode plate; It includes a case for receiving the electrode assembly, A lithium secondary battery, characterized in that the thickness is 5% or less of the width. 9. The method of claim 8, The lithium secondary battery is a lithium secondary battery, characterized in that formed in the shape according to any one of claims 2 to 7.

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