Electrode assembly and secondary battery including the same

Abstract

The present invention relates to an electrode assembly and a secondary battery including the electrode assembly. A jelly-roll-type electrode assembly includes a positive electrode uncoated portion formed on a positive electrode plate and a negative electrode uncoated portion formed on a negative electrode plate. The negative electrode uncoated portion includes a first negative electrode uncoated portion and a second negative electrode uncoated portion, the first negative electrode uncoated portion being formed between the front end and the rear end of the negative electrode plate in a winding direction, and the second negative electrode uncoated portion being formed at the rear end of the negative electrode plate. A negative electrode tab is disposed in the first negative electrode uncoated portion.

Description

Technical Field

[0001] The present invention relates to an electrode assembly and a secondary battery including the electrode assembly. Background Art

[0002] Typically, a secondary battery is formed by housing an electrode assembly consisting of a positive electrode plate, a negative electrode plate, and a separator sandwiched between the two electrode plates together with an electrolyte in a housing. Unlike a non-rechargeable primary battery, the secondary battery is a rechargeable and dischargeable battery. With the development of technology and increased production for mobile devices such as mobile phones and laptop computers, the demand for secondary batteries as energy sources is increasing rapidly. In recent years, electric vehicles and hybrid vehicles have been actively researched and developed as alternative energy sources to replace fossil fuels.

[0003] Commercial secondary batteries currently include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries and lithium secondary batteries. Among them, when compared with nickel-based secondary batteries, lithium secondary batteries have attracted attention due to their advantages such as free charge and discharge, very low self-discharge rate and high energy density due to almost no memory effect.

[0004] In order to increase the output of lithium secondary batteries, the resistance of the battery must be reduced. In a limited volume, increasing the number of electrodes is effective. In addition, the length of the electrode plate gradually increases with the demand for high capacity and high output of lithium secondary batteries, which will lead to increased internal resistance. This problem can also be alleviated by increasing the number of electrode tabs. However, the increase in the number of electrode tabs not only increases the amount of material and working hours required, but also reduces the space utilization rate of the internal space of the lithium secondary battery.

[0005] In addition, generally, when a lithium secondary battery is overcharged to a certain voltage or higher, the reaction between the positive electrode active material and the electrolyte constituting the lithium secondary battery will be excessive, resulting in structural collapse of the positive electrode active material and oxidation reaction of the electrolyte, so lithium will also be deposited. If this state continues, the lithium secondary battery will be ignited or exploded.

[0006] The above information disclosed in the art used as background art of the present invention is only for improving understanding of the background art of the present invention and therefore may include information that does not constitute related art. Summary of the invention

[0007] Technical issues

[0008] In order to solve the above problems, an object of the present invention is to provide an electrode assembly capable of minimizing the number of electrode tabs while reducing the resistance of a secondary battery and a secondary battery including the same.

[0009] Another object of the present invention is to provide an electrode assembly capable of minimizing lithium deposition during overcharging and a secondary battery including the same.

[0010] Technical Solution

[0011] In an electrode assembly for achieving the above-mentioned purpose according to the present invention and a secondary battery including the electrode assembly, the electrode assembly includes: a positive electrode plate, including a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector, wherein an uncoated portion of the positive electrode not coated with the positive electrode active material is formed in the positive electrode current collector; a negative electrode plate, including a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector, wherein an uncoated portion of the negative electrode not coated with the negative electrode active material is formed in the negative electrode current collector; a separator, disposed between the positive electrode plate and the negative electrode plate; a positive electrode tab, electrically connected to the positive electrode of the positive electrode plate a current collector; and a negative electrode tab, a negative electrode current collector electrically connected to the negative electrode plate, wherein the positive electrode plate, the negative electrode plate and the separator are wound in a sequentially stacked state, the positive electrode uncoated portion is arranged between the front end and the rear end of the positive electrode plate in the winding direction, the positive electrode tab is attached to the positive electrode current collector on the positive electrode uncoated portion, the negative electrode uncoated portion includes a main negative electrode uncoated portion and a secondary negative electrode uncoated portion, the main negative electrode uncoated portion is formed between the front end and the rear end of the negative electrode plate in the winding direction, the secondary negative electrode uncoated portion is formed on the rear end of the negative electrode plate, and the negative electrode tab is arranged on the main negative electrode uncoated portion.

[0012] According to the present invention, the positive electrode uncoated portion may include a main positive electrode uncoated portion and a secondary positive electrode uncoated portion, the main positive electrode uncoated portion and the secondary positive electrode uncoated portion are formed to be spaced apart from each other between the front end and the rear end of the positive electrode plate in the winding direction, and the positive electrode tab may include a first positive electrode tab and a second positive electrode tab, the first positive electrode tab and the second positive electrode tab are respectively arranged on the main positive electrode uncoated portion and the secondary positive electrode uncoated portion. Here, the first positive electrode tab and the second positive electrode tab may be arranged on a straight line in the radial direction in a wound state. The main positive electrode uncoated portion may be arranged closer to the front end of the positive electrode plate than the secondary positive electrode uncoated portion, and the main positive electrode uncoated portion may extend in the winding direction to a width greater than the width of the first positive electrode tab to form a positive electrode semi-coated portion, wherein the positive electrode semi-coated portion may be arranged one circle inside the first positive electrode tab in a wound state. The main positive electrode uncoated portion can be set to be closer to the front end of the positive electrode plate than the secondary positive electrode uncoated portion, and the main positive electrode uncoated portion can extend in the winding direction to a width greater than the width of the first positive electrode tab to form a positive electrode semi-coated portion, wherein the positive electrode semi-coated portion can be set one circle outside the first positive electrode tab in the wound state.

[0013] The positive electrode plate may include a positive electrode semi-coated portion on which a positive electrode coating is not formed, the positive electrode semi-coated portion being located at a position spaced apart from and adjacent to the main positive electrode uncoated portion in the winding direction, wherein the positive electrode semi-coated portion may be disposed at a relatively front end side compared to the main positive electrode uncoated portion, and the positive electrode semi-coated portion is disposed one circle inside the first positive electrode tab in a wound state, or the positive electrode semi-coated portion may be disposed at a relatively rear end side compared to the main positive electrode uncoated portion, and the positive electrode semi-coated portion is disposed one circle outside the first positive electrode tab in a wound state.

[0014] In the electrode assembly and the secondary battery including the electrode assembly according to the present invention, the first positive electrode tab and the second positive electrode tab may be arranged on a straight line in the radial direction in a wound state, and the positive electrode tab and the negative electrode tab may be arranged in a region corresponding to 1 / 5 to 4 / 5 of the radius of the transverse section in a wound state. Here, the positive electrode tab and the negative electrode tab may be arranged on the same line in the longitudinal direction of the electrode assembly in a wound state, but the lower portion of the positive electrode tab and the upper portion of the negative electrode tab may be arranged not to overlap each other.

[0015] The secondary battery according to the present invention includes: an electrode assembly according to the present invention; a shell configured to accommodate the electrode assembly and an electrolyte in an inner space of the shell; and a cover plate coupled to an upper portion of the shell to seal the shell, wherein an uncoated portion of the sub-negative electrode can be attached to an inner surface of the shell.

[0016] Beneficial Effects

[0017] The electrode assembly and the secondary battery including the same according to the present invention can reduce the number of negative electrode tabs without increasing the resistance of the secondary battery by allowing an uncoated portion formed at one end of a negative electrode plate to be used as a negative electrode tab, thereby minimizing the total number of electrode tabs.

[0018] Furthermore, the electrode assembly and the secondary battery including the same according to the present invention can form an uncoated portion on a positive electrode plate on which a positive electrode tab is not formed among positive electrode plates adjacent to a negative electrode tab, thereby preventing lithium from being deposited during overcharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1a , Figure 1b , Figure 1c and Figure 1d are a perspective view, an exploded perspective view, a longitudinal sectional view, and a sectional view showing a secondary battery according to an embodiment of the present invention.

[0020] Figure 2 It is shown Figure 1a to Figure 1d0 is a cross-sectional view of a state before an electrode assembly of a secondary battery is wound.

[0021] Figure 3 It is shown Figure 2 An enlarged transverse cross-sectional view of a partial enlarged cross-sectional view of the electrode assembly shown in FIG. 1 after winding.

[0022] Figures 4a to 4c It is also shown Figure 3 An enlarged transverse cross-sectional view of the attachment positions of the positive electrode tab and the negative electrode tab in the cross-sectional view of the electrode assembly shown in FIG.

[0023] Figure 5 It is shown Figure 1a to Figure 1d 0 is a cross-sectional view of another example of a state before the electrode assembly of the secondary battery is wound.

[0024] Figure 6 It is shown Figure 5 An enlarged transverse cross-sectional view of a partial enlarged cross-sectional view of the electrode assembly shown in FIG. 1 after winding.

[0025] Figure 7 It is shown Figure 1a to Figure 1d 0 is a cross-sectional view of another example of a state before the electrode assembly of the secondary battery is wound.

[0026] Figure 8 It is shown Figure 7 An enlarged transverse cross-sectional view of a partial enlarged cross-sectional view of the electrode assembly shown in FIG. 1 after winding.

[0027] Fig. 9 It is shown Figure 1a to Figure 1d 0 is a cross-sectional view of another example of a state before the electrode assembly of the secondary battery is wound.

[0028] Fig.10 It is shown Fig. 9 An enlarged transverse cross-sectional view of a partial enlarged cross-sectional view of the electrode assembly shown in FIG. 1 after winding.

[0029] Fig.11 It is shown Figure 1a to Figure 1d 0 is a cross-sectional view of a state before an electrode assembly of a secondary battery is wound.

[0030] Fig.12 It is shown Fig.11 An enlarged transverse cross-sectional view of a partial enlarged cross-sectional view of the electrode assembly shown in FIG. 1 after winding.

[0031] Fig.13 It is shown Fig.11 An enlarged transverse cross-sectional view of a partial enlarged cross-sectional view of the electrode assembly shown in FIG. 1 after being wound in different ways.

[0032] Fig.14 is a cross-sectional view showing a state before an electrode assembly of a secondary battery according to another embodiment of the present invention is wound.

[0033] Fig.15 It is shown Fig.14 An enlarged transverse sectional view of a portion of the electrode assembly shown in FIG. 1 after winding. DETAILED DESCRIPTION

[0034] Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings. However, the present invention may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that those skilled in the art will thoroughly understand the present invention. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the present invention to those skilled in the art.

[0035] In addition, in the accompanying drawings, the sizes of layers and regions may be exaggerated for clarity. The same reference numerals always represent the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items. In this specification, it will also be understood that when component A is referred to as being connected to component B, component A may be directly connected to component B, or indirectly connected to component B, and component C is located between them.

[0036] The terms used herein are only for illustrative purposes of the present invention and should not be construed as limiting the meaning or scope of the present invention. As used in this specification, unless a specific situation is clearly indicated according to the context, the singular form may include the plural form. In addition, the expression "including" and / or its variations used in this specification neither limit the shapes, quantities, processes, operations, members, elements and / or these groups mentioned, nor exclude the existence or addition of one or more other different shapes, quantities, processes, operations, members, elements and / or these groups. The term "and / or" used herein includes any combination and all combinations of one or more of the related listed items.

[0037] As used herein, terms such as "first", "second", etc. are used to describe various components, components, regions, layers and / or parts. However, it is obvious that components, components, regions, layers and / or parts should not be limited by these terms. The term does not mean a specific order, up and down, or superiority, but is only used to distinguish one component, component, region, layer or part from another component, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first component, first component, first region, first layer or first part described may also be referred to as the second component, second component, second region, second layer or second part.

[0038] For ease of description, spatially relative terms such as "below", "under", "below", "above", "on", etc. are used here to describe the relationship between an element or feature and another (other) element or feature as shown in the drawings. These spatially relative terms are intended to facilitate understanding of the present invention according to various process states or use states of the present invention, and therefore, the present invention is not limited thereto. For example, the elements or features shown in the drawings are flipped, and the elements or features described as "below" or "below" can be changed to "above" or "on". Therefore, the term "below" can cover the terms "above" or "below".

[0039] Figure 1a , Figure 1b , Figure 1c and Figure 1d 1 is a perspective view, an exploded perspective view, a longitudinal cross-sectional view, and a transverse cross-sectional view showing a secondary battery 100 according to an embodiment of the present invention. Here, the longitudinal cross-section is a cross-section cut in the longitudinal direction of the secondary battery 100, and the transverse cross-section is a cross-section cut in the winding direction of the secondary battery.

[0040] like Figure 1a , Figure 1b , Figure 1c and Figure 1d As shown in , a secondary battery 100 according to the present invention includes a case 110 , an electrode assembly 120 accommodated in the case 110 , and a cap assembly 130 sealing an opening of an upper end of the case 110 .

[0041] The housing 110 includes a circular bottom 111 and a side 112 extending upward from the bottom 111 at a predetermined length. Here, although the secondary battery 100 is shown as a cylindrical secondary battery, it is applicable to a prismatic secondary battery and a pouch-type secondary battery, and in the present invention, the shape of the secondary battery is not limited to a cylindrical shape. During the process of manufacturing the secondary battery 100, the upper part of the housing 110 can be opened. Therefore, during the process of assembling the secondary battery, the electrode assembly 120 can be inserted into the housing 110 together with the electrolyte. The housing 110 can be made of steel, steel alloy, aluminum, aluminum alloy or its equivalent, but the material of the housing 110 is not limited thereto. In addition, in the housing 110, an inwardly concave beading part 113 can be formed at the lower part of the housing 110 relative to the cap assembly 130, and an inwardly bent crimping part 114 can be formed at the upper part of the housing 110 to prevent the cap assembly 130 from being separated to the outside.

[0042] The electrode assembly 120 may be accommodated in the case 110 together with the electrolyte in a state of being wound into a substantially cylindrical shape. Here, the electrolyte is an organic liquid containing salt, which is injected so that lithium ions move between the positive electrode plate and the negative electrode plate constituting the electrode assembly 120, and includes a non-aqueous organic electrolyte that is a mixture of a lithium salt (such as LiPF6, LiBF4, and LiClO4) and a high-purity organic solvent, but the present invention is not limited thereto.

[0043] The electrode assembly 120 includes a negative electrode plate 121 coated with a negative electrode active material, a positive electrode plate 122 coated with a positive electrode active material, and a separator 123, which is placed between the negative electrode plate 121 and the positive electrode plate 122 to prevent a short circuit from occurring between the negative electrode plate 121 and the positive electrode plate 122 and to allow only lithium ions to move. In addition, a negative electrode tab 124 protruding downward by a predetermined length may be attached to the negative electrode plate 121, and positive electrode tabs 125 and 129 each protruding upward by a predetermined length may be attached to the positive electrode plate 122. On the other hand, unlike the example shown, the protruding directions may be interchanged with each other. Here, "attachment" may be understood as being electrically connected to each other, i.e., short-circuited using means such as welding or bonding.

[0044] like Figure 1d As shown in , the electrode assembly 120 ideally has a circular cross-sectional shape, and an empty space including a winding center portion c may be formed during the winding process, which may be referred to as a core region. However, unlike the example shown, the cross-sectional shape of the core region does not always have to be circular.

[0045] In addition, refer to Figure 2 , showing Figure 1a to Figure 1d FIG. 1 is an exploded perspective view of a state before the electrode assembly of a secondary battery is wound. Figure 3 , showing that Figure 2 FIG. 1 is an enlarged transverse cross-sectional view of a portion of a transverse cross-sectional view of a secondary battery of an electrode assembly shown in FIG. Figure 2 and Figure 3 Configurations of a secondary battery and an electrode assembly according to the present invention are described in detail.

[0046] First, in the negative electrode plate 121 of the electrode assembly 120, a negative electrode coating 121b is coated on both sides of a negative electrode collector plate 121a, and the negative electrode coating 121b is an active material made of a transition metal oxide, and the negative electrode collector plate 121a is a plate-shaped metal foil made of copper (Cu) or nickel (Ni). The negative electrode plate 121 is provided with a negative electrode tab 124 attached to one surface of the negative electrode collector plate 121a. The negative electrode tab 124 may be partially welded and attached to the negative electrode collector plate 121a, and protrude downward by a predetermined length in the longitudinal direction of the electrode assembly 120.

[0047] In addition, the negative electrode collector plate 121a is provided with a first negative electrode uncoated portion 121c on which the negative electrode coating 121b is not formed at both sides, which are one side in the winding direction x and the opposite side in the winding direction x of one surface of the negative electrode collector plate 121a to which the negative electrode tab 124 is attached. That is, the negative electrode tab 124 is attached to one surface of the negative electrode collector plate 121a of the negative electrode plate 121 so as to be spaced apart from the negative electrode coating 121b. In addition, on the other surface which is the opposite surface of the one surface on which the negative electrode tab 124 is attached, the negative electrode collector plate 121a is further provided with a second negative electrode uncoated portion 121d on which the negative electrode coating 121b is not formed on an area corresponding to the area corresponding to the negative electrode tab 124 and the area on which the first negative electrode uncoated portion 121c is provided.

[0048] In the transverse section of the wound electrode assembly 120, the negative electrode tab 124 may be disposed at any position between 1 / 5 and 4 / 5 of the transverse section radius r, which is the length between the winding center c and the outermost portion o. Preferably, the negative electrode tab 124 may be disposed at the approximate center of the transverse section radius r. The negative electrode tab 124 may be made of copper or nickel material, but the present invention is not limited thereto.

[0049] The positive electrode plate 122 is coated with a positive electrode coating 122b on both surfaces of a positive electrode collector 122a, which is an active material made of a transition metal oxide, and the positive electrode collector 122a is a plate-shaped metal foil made of aluminum (Al). The positive electrode plate 122 is provided with a positive electrode tab 125 attached to one surface of the positive electrode collector plate 122a. The positive electrode tab 125 may be partially welded and attached to the positive electrode collector 122a, and protrude upward by a predetermined length in the longitudinal direction of the electrode assembly 120.

[0050] In the transverse section of the wound electrode assembly 120, the positive electrode tab 125 may be disposed at any position between 1 / 5 and 4 / 5 of the transverse section radius r, where the transverse section radius r is the length between the winding center c and the outermost portion o. Preferably, the positive electrode tab 125 may be disposed at the approximate center of the transverse section radius r. In addition, the positive electrode tab 125 may be disposed on a surface facing the negative electrode tab 124 relative to the separator 123 in the wound electrode assembly 120, but the present invention is not limited thereto. Figures 4a to 4cAs shown in , the positive electrode tab 125 and the negative electrode tab 124 may be disposed on the same surface of the positive electrode plate 122 and the negative electrode plate 121, or may be disposed on opposite surfaces of the positive electrode plate 122 and the negative electrode plate 121, respectively. Here, the same surface may be the same surface facing the outermost side o of the wound electrode assembly 120, or may be the surface facing the winding center c in the same manner. In addition, the opposite surface means that when the positive electrode tab 125 is formed on the surface facing the outermost side o of the wound electrode assembly 120, the negative electrode tab 124 is formed on the surface facing the winding center c, and vice versa. That is, in the present invention, the surfaces to which the positive electrode tab 125 and the negative electrode tab 124 are attached are not limited to the two surfaces of the positive electrode plate 122 and the negative electrode plate 121, each made of foil.

[0051] As described above, in the transverse section of the electrode assembly 120 wound with both the positive electrode tab 125 and the negative electrode tab 124, since the positive electrode tab 125 and the negative electrode tab 124 are arranged between 1 / 5 and 4 / 5 of the transverse section radius r, which is the length between the winding center c and the outermost portion o, the positive electrode tab 125 and the negative electrode tab 124 can be arranged to be aligned on the same line in the longitudinal direction in the wound electrode assembly 120. Here, the positive electrode tab 125 and the negative electrode tab 124 are arranged not to overlap each other on the same line. That is, the lower portion of the positive electrode tab 125 and the upper portion of the negative electrode tab 124 can be arranged on the same line in the longitudinal direction of the electrode assembly 120 so as not to overlap each other. This is to prevent a decrease in the winding roundness rate, which may occur when the positive electrode tab 125 and the negative electrode tab 124, which are thicker than the positive electrode plate 122 and the negative electrode plate 121, overlap each other in the longitudinal direction of the electrode assembly 120. In the electrode assembly 120, the positive electrode tab 125 may be disposed at the outer side of the negative electrode tab 124 with respect to the separator 123. The positive electrode tab 125 may be made of an aluminum material, but the present invention is not limited thereto.

[0052] In addition, the positive electrode collector plate 122a is provided with a first positive electrode uncoated portion 122c on which the positive electrode coating 122b is not formed at both sides, which are one side in the winding direction x and the opposite side in the winding direction x of one surface of the positive electrode collector plate 122a to which the positive electrode tab 125 is attached. That is, the positive electrode tab 125 is attached to one surface of the positive electrode collector plate 122a of the positive electrode plate 122 so as to be spaced apart from the positive electrode coating 122b. In addition, on the other surface which is the opposite surface of the one surface on which the positive electrode tab 125 is attached, the positive electrode plate 122 is further provided with a second positive electrode uncoated portion 122d on which the positive electrode coating 122b is not formed on an area corresponding to the area corresponding to the positive electrode tab 125 and the area on which the first positive electrode uncoated portion 122c is provided.

[0053] In addition, the positive electrode plate 122 is formed so that the second positive electrode uncoated portion 122d further extends in the opposite direction of the winding direction x. That is, the positive electrode plate 122 may be provided with a second positive electrode uncoated portion 122d on which the positive electrode coating 122b is not formed at a predetermined length from the area to which the positive electrode tab 125 is attached in the opposite direction of the winding direction x on the other surface of the positive electrode collector plate 122a. Preferably, the second positive electrode uncoated portion 122d extends one circle in the direction of the winding center portion c from the portion to which the positive electrode tab 125 is attached in the wound positive electrode plate 122. As described above, due to the second positive electrode uncoated portion 122d, the positive electrode plate 122 is provided with a positive electrode half-coated portion 122e extending one circle from the positive electrode tab 125 in the opposite direction of the winding direction x. Here, the positive electrode half-coated portion 122e means that the positive electrode coating 122b is formed only on one surface of the positive electrode collector plate 122a. In Figure 2 and Figure 3 In the embodiment, the positive electrode semi-coated portion 122e is provided with a positive electrode coating on one surface to which a positive electrode tab is attached, and is provided with an uncoated portion on the other surface as an opposite surface, and vice versa.

[0054] In this case, on the positive electrode plate 122 as the closest to the negative electrode plate 121, the wound electrode assembly 120 is provided with a positive electrode half-coating portion 122e on an area of ​​the positive electrode plate 122 on which the positive electrode tab 125 is not attached, on the inner side and the outer side of the portion on which the negative electrode tab 124 is attached. Here, the inner side means an area of ​​the positive electrode plate in a direction closest to the winding center c with respect to the negative electrode plate 121, and the outer side means an area of ​​the positive electrode plate in a direction closest to the outermost side o with respect to the negative electrode plate 121. As described above, the positive electrode plate 122 forms the positive electrode half-coating portion 122e at a position corresponding to the negative electrode tab 124 to prevent lithium from being deposited during overcharging.

[0055] The negative electrode tab 124 of the electrode assembly 120 may be welded to the bottom 111 of the case 110. Therefore, the case 110 may be used as a negative electrode. Of course, conversely, the first positive electrode tab 125 and the second positive electrode tab 129 may be welded to the bottom 111 of the case 110, and in this case, the case 110 may be used as a positive electrode.

[0056] In addition, a first insulating plate 126 may be placed between the electrode assembly 120 and the bottom 111, the first insulating plate 126 being coupled to the housing 110 and having a first hole 126a at its center and a second hole 126b formed outside its center. The first insulating plate 126 may be used to prevent the electrode assembly 120 from electrically contacting the bottom 111 of the housing 110. Specifically, the first insulating plate 126 may be used to prevent the positive electrode plate 122 of the electrode assembly 120 from electrically contacting the bottom 111. Here, the first hole 126a may be used to allow the gas to move quickly upward when a large amount of gas is generated due to an abnormality in the secondary battery, and the second hole 126b may be used to allow the negative electrode tab 124 to pass therethrough to be welded to the bottom 111. In addition, the electrode assembly 120 is also provided with a center pin (not shown) in the form of a hollow circular tube at approximately the center, so that a large amount of gas generated when the secondary battery is abnormal is easily discharged through the internal channel of the center pin.

[0057] In addition, a second insulating plate 127 may be placed between the electrode assembly 120 and the cap assembly 130, the second insulating plate 127 being coupled to the case 110 and having a first hole 127a located at the center thereof and a plurality of second holes 127b formed outside the center thereof. The second insulating plate 127 may be used to prevent the electrode assembly 120 from electrically contacting the cap assembly 130. Specifically, the second insulating plate 127 may be used to prevent the negative electrode plate 121 of the electrode assembly 120 from electrically contacting the cap assembly 130. Here, the first hole 127a may be used to allow the gas to quickly move to the cap assembly 130 when a large amount of gas is generated due to an abnormality in the secondary battery, and the second hole 127b may be used to allow the positive electrode tab 125 to pass therethrough to be welded to the cap assembly 130. In addition, the remaining second holes 127b may be used to allow the electrolyte to quickly flow into the electrode assembly 120 during the process of injecting the electrolyte. The electrolyte may be used as a moving medium for lithium ions generated by electrochemical reactions in the positive and negative electrode plates inside the battery during charging and discharging.

[0058] The cover assembly 130 may include an upper cover 131 having a plurality of through holes 131d, a safety plate 133 mounted on a lower portion of the upper cover 131, a connecting ring 135 mounted on a lower portion of the safety plate 133, a lower cover 136 coupled to the connecting ring 135 and having a first through hole 136a and a second through hole 136b, a lower plate 137 fixed to a lower portion of the lower cover 136 and electrically connected to the positive electrode tab 125, and an insulating gasket 138 for insulating the upper cover 131, the safety plate 133, the connecting ring 135, and the lower cover 136 from the side 112 of the shell 110.

[0059] Here, the insulating gasket 138 may be substantially squeezed between the curling portion 113 and the crimping portion 114 formed on the side of the housing 110. In addition, the through hole 131d formed in the upper cover 131 and the through hole 136b formed in the lower cover 136 may be used to discharge the internal gas to the outside when an abnormal internal pressure occurs inside the housing 110. Of course, when the safety plate 133 is turned up due to the internal pressure, the safety plate 133 may be electrically separated from the lower plate 137, and then, the safety plate 133 may be torn to discharge the internal gas to the outside.

[0060] Reference Figure 5 , showing Figure 1a to Figure 1d , which is a cross-sectional view of another example of a state before the electrode assembly of a secondary battery is wound. Figure 6 , showing Figure 5 An enlarged transverse cross-sectional view of a partial enlarged cross-sectional view of the electrode assembly shown in FIG. 1 after winding.

[0061] As mentioned above, Figure 5 and Figure 6 The configurations of the case 110 of the secondary battery, the negative electrode plate 121 of the electrode assembly 120, the separator 123 of the electrode assembly 120, and the cap assembly 130 shown in FIG. 1 may be the same as those of Figure 1a , Figure 1b and Figure 1d The configuration of the secondary battery 100 shown in FIG. 1 is the same as that of the secondary battery 100 shown in FIG. Figure 1a , Figure 1b , Figure 1d , Figure 5 and Figure 6 The configuration of the positive electrode plate 122 of the electrode assembly 220 of the secondary battery will be mainly described.

[0062] The positive electrode plate 122 is coated with a positive electrode coating 122b on both surfaces of a positive electrode current collector 122a, which is an active material made of a transition metal oxide, and the positive electrode current collector 122a is a plate-shaped metal foil made of aluminum (Al). The positive electrode plate 122 is provided with a positive electrode tab 125 attached to one surface of the positive electrode current collector plate 122a. The positive electrode tab 125 may be partially welded and attached to the positive electrode current collector 122a, and protrude upward by a predetermined length in the longitudinal direction of the electrode assembly 220.

[0063] The positive electrode tab 125 may be disposed at a substantially center of the transverse cross-sectional radius r of the wound electrode assembly 220. In addition, the positive electrode tab 125 may be disposed at the same position facing the negative electrode tab 124 relative to the separator 123 in the wound electrode assembly 220, but the present invention is not limited thereto. Figures 4a to 4c As shown in , the positive electrode tab 125 and the negative electrode tab 124 may be disposed on the same surface of the positive electrode plate 122 and the negative electrode plate 121, or may be disposed on opposite surfaces of the positive electrode plate 122 and the negative electrode plate 121, respectively. That is, in the present invention, the surfaces to which the positive electrode tab 125 and the negative electrode tab 124 are attached are not limited to the two surfaces of the positive electrode plate 122 and the negative electrode plate 121, each made of foil.

[0064] In addition, the positive electrode tab 125 and the negative electrode tab 124 may be arranged to be aligned on the same line in the longitudinal direction of the wound electrode assembly 220. In addition, the positive electrode tab 125 and the negative electrode tab 124 may be arranged not to overlap each other in the longitudinal direction of the wound electrode assembly 220. This is to prevent a reduction in the winding roundness rate, which may occur when the positive electrode tab 125 and the negative electrode tab 124, which are thicker than the positive electrode plate 122 and the negative electrode plate 121, overlap each other in the longitudinal direction of the electrode assembly 220. In the electrode assembly 220, the positive electrode tab 125 may be arranged outside the negative electrode tab 124 relative to the separator 123. The positive electrode tab 125 may be made of an aluminum material, but the present invention is not limited thereto.

[0065] In addition, the positive electrode collector plate 122a is provided with a first positive electrode uncoated portion 122c on which the positive electrode coating 122b is not formed at both sides, which are one side in the winding direction x and the opposite side in the winding direction x of one surface of the positive electrode collector plate 122a to which the positive electrode tab 125 is attached. That is, the positive electrode tab 125 is attached to one surface of the positive electrode collector plate 122a of the positive electrode plate 122 so as to be spaced apart from the positive electrode coating 122b. In addition, on the other surface which is the opposite surface of the one surface on which the positive electrode tab 125 is attached, the positive electrode plate 122 is further provided with a second positive electrode uncoated portion 122d on which the positive electrode coating 122b is not formed on an area corresponding to the area corresponding to the positive electrode tab 125 and the area on which the first positive electrode uncoated portion 122c is provided.

[0066] In addition, in the wound electrode assembly 220, on the positive electrode plate 122 as the closest to the negative electrode plate 121, on the inner and outer sides of the portion on which the negative electrode tab 124 is attached, the positive electrode plate 122 is provided with a positive electrode half-coating portion 222e on the positive electrode plate 122 to which the positive electrode tab 125 is not attached. Here, the positive electrode half-coating portion 222e means that the positive electrode coating 122b is formed only on one surface of the positive electrode current collector plate 122a, and the opposite surface is provided as an uncoated portion on which the positive electrode coating 122b is not formed. In the wound electrode assembly 220, the positive electrode half-coating portion 222e is provided on a region of the positive electrode plate 122 as the closest to the negative electrode plate 121, which is located on the inner side of the portion on which the negative electrode tab 124 is attached.

[0067] Here, the inner side means the area of ​​the positive electrode plate disposed in the direction of the winding center c relative to the negative electrode plate 121, and the outer side means the area of ​​the positive electrode plate disposed in the direction of the outermost side o relative to the negative electrode plate 121. In addition, the positive electrode half-coated portion 222e may be formed to have a width greater than the width of each of the first negative electrode uncoated portion 121c and the second negative electrode uncoated portion 121d in the direction perpendicular to the longitudinal direction. This is to prevent misalignment of the positive electrode tab 125, the negative electrode tab 124, and the positive electrode half-coated portion 222e when the electrode assembly 220 is wound.

[0068] In addition, the positive electrode half-coating portion 222e is Figure 5 and Figure 6 12 is shown as having a positive electrode coating portion 122b formed on one surface to which a positive electrode tab 125 is attached and an uncoated portion formed on the other surface as an opposite surface, and vice versa. As described above, the positive electrode plate 122 forms a positive electrode semi-coating portion 222e at a position corresponding to the negative electrode tab 124 to prevent lithium from being deposited when the secondary battery is overcharged.

[0069] Reference Figure 7 , showing Figure 1a to Figure 1d , which is a cross-sectional view of another example of a state before the electrode assembly of a secondary battery is wound. Figure 8 , showing Figure 7 An enlarged cross-sectional view of a partial enlarged transverse cross-sectional view of the electrode assembly shown in FIG. 1 after winding.

[0070] As mentioned above, Figure 7 and Figure 8 The configurations of the case 110 of the secondary battery, the negative electrode plate 121 of the electrode assembly 120, the separator 123 of the electrode assembly 120, and the cap assembly 130 shown in FIG. 1 may be the same as those of Figure 1a , Figure 1b and Figure 1d The configuration of the secondary battery 100 shown in FIG. 1 is the same as that of the secondary battery 100 shown in FIG. Figure 1a , Figure 1b , Figure 1d , Figure 7 and Figure 8 The configuration of the positive electrode plate 122 of the electrode assembly 320 of the secondary battery will be mainly described.

[0071] The positive electrode plate 122 is coated with a positive electrode coating 122b on both surfaces of a positive electrode current collector 122a, which is an active material made of a transition metal oxide, and the positive electrode current collector 122a is a plate-shaped metal foil made of aluminum (Al). The positive electrode plate 122 is provided with a positive electrode tab 125 attached to one surface of the positive electrode current collector plate 122a. The positive electrode tab 125 may be partially welded and attached to the positive electrode current collector 122a, and protrude upward by a predetermined length in the longitudinal direction of the electrode assembly 320.

[0072] The positive electrode tab 125 may be disposed at a substantially center of the transverse cross-sectional radius r of the wound electrode assembly 220. In addition, the positive electrode tab 125 may be disposed at the same position facing the negative electrode tab 124 relative to the separator 123 in the wound electrode assembly 320, but the present invention is not limited thereto. Figures 4a to 4c As shown in , the positive electrode tab 125 and the negative electrode tab 124 may be disposed on the same surface of the positive electrode plate 122 and the negative electrode plate 121, or may be disposed on opposite surfaces of the positive electrode plate 122 and the negative electrode plate 121, respectively. That is, in the present invention, the surfaces to which the positive electrode tab 125 and the negative electrode tab 124 are attached are not limited to the two surfaces of the positive electrode plate 122 and the negative electrode plate 121, each made of foil.

[0073] In addition, the positive electrode tab 125 and the negative electrode tab 124 may be arranged to be aligned on the same line in the longitudinal direction of the wound electrode assembly 320. In addition, the positive electrode tab 125 and the negative electrode tab 124 may be arranged not to overlap each other in the longitudinal direction of the wound electrode assembly 320. This is to prevent a reduction in the winding roundness rate, which may occur when the positive electrode tab 125 and the negative electrode tab 124, which are thicker than the positive electrode plate 122 and the negative electrode plate 121, overlap each other in the longitudinal direction of the electrode assembly 320. In the electrode assembly 320, the positive electrode tab 125 may be arranged inside the negative electrode plate 121 relative to the separator 123 at the portion to which the negative electrode tab 124 is attached. The positive electrode tab 125 may be made of an aluminum material, but the present invention is not limited thereto.

[0074] In addition, the positive electrode collector plate 122a is provided with a first positive electrode uncoated portion 122c on which the positive electrode coating 122b is not formed at both sides, which are one side in the winding direction x and the opposite side in the winding direction x of one surface of the positive electrode collector plate 122a to which the positive electrode tab 125 is attached. That is, the positive electrode tab 125 is attached to one surface of the positive electrode collector plate 122a of the positive electrode plate 122 so as to be spaced apart from the positive electrode coating 122b. In addition, on the other surface which is the opposite surface of the one surface on which the positive electrode tab 125 is attached, the positive electrode plate 122 is further provided with a second positive electrode uncoated portion 122d on which the positive electrode coating 122b is not formed on an area corresponding to the area corresponding to the positive electrode tab 125 and the area on which the first positive electrode uncoated portion 122c is provided.

[0075] In addition, the positive electrode plate 122 is formed so that the second positive electrode uncoated portion 122d further extends in the winding direction x. That is, the positive electrode plate 122 may be provided with a second positive electrode uncoated portion 122d on which the positive electrode coating 122b is not formed at a predetermined length in the winding direction x from the area to which the positive electrode tab 125 is attached on the other surface of the positive electrode collector plate 122a. Preferably, the second positive electrode uncoated portion 122d extends one circle in the direction of the outermost side o from the portion to which the positive electrode tab 125 is attached in the wound positive electrode plate 122. As described above, due to the second positive electrode uncoated portion 122d, the positive electrode plate 122 is provided with a positive electrode half-coated portion 322e extending one circle from the positive electrode tab 125 in the winding direction x. Here, the positive electrode half-coated portion 322e means that the positive electrode coating 122b is formed only on one surface of the positive electrode collector plate 122a. In Figure 7 and Figure 8In the embodiment, the positive electrode semi-coated portion 322e is provided with the positive electrode coated portion 122b on one surface to which the positive electrode tab 125 is attached, and is provided with an uncoated portion on the other surface as an opposite surface, and vice versa.

[0076] In this case, the wound electrode assembly 320 is provided with a positive electrode half-coating portion 322e on the positive electrode plate 122 to which the positive electrode tab 125 is not attached, on the positive electrode plate 122 as the closest to the negative electrode plate 121, on the inner side and the outer side of the portion to which the negative electrode tab 124 is attached. Here, the inner side means the positive electrode plate provided in the direction of the winding center c with respect to the negative electrode plate 121, and the outer side means the positive electrode plate provided in the direction of the outermost side o with respect to the negative electrode plate 121. As described above, the positive electrode plate 122 forms the positive electrode half-coating portion 322e at a position corresponding to the negative electrode tab 124 to prevent lithium from being deposited during overcharge.

[0077] Reference Fig. 9 , showing Figure 1a to Figure 1d , which is a cross-sectional view of another example of a state before the electrode assembly of a secondary battery is wound. Fig.10 , showing Fig. 9 An enlarged transverse cross-sectional view of a partial enlarged cross-sectional view of the electrode assembly shown in FIG. 1 after winding.

[0078] As mentioned above, Fig. 9 and Fig.10 The configurations of the case 110 of the secondary battery, the negative electrode plate 121 of the electrode assembly 120, the separator 123 of the electrode assembly 120, and the cap assembly 130 shown in FIG. 1 may be the same as those of Figure 1a , Figure 1b and Figure 1d The configuration of the secondary battery 100 shown in FIG. 1 is the same as that of the secondary battery 100 shown in FIG. Figure 1a , Figure 1b , Figure 1d , Fig. 9 and Fig.10 The configuration of the positive electrode plate 122 of the electrode assembly 420 of the secondary battery will be mainly described.

[0079] The positive electrode plate 122 is coated with a positive electrode coating 122b on both surfaces of a positive electrode current collector 122a, which is an active material made of a transition metal oxide, and the positive electrode current collector 122a is a plate-shaped metal foil made of aluminum (Al). The positive electrode plate 122 is provided with a positive electrode tab 125 attached to one surface of the positive electrode current collector plate 122a. The positive electrode tab 125 may be partially welded and attached to the positive electrode current collector 122a, and protrude upward by a predetermined length in the longitudinal direction of the electrode assembly 420.

[0080] The positive electrode tab 125 may be disposed at a substantially center of the transverse cross-sectional radius r of the wound electrode assembly 420. In addition, the positive electrode tab 125 may be disposed at the same position facing the negative electrode tab 124 relative to the separator 123 in the wound electrode assembly 420, but the present invention is not limited thereto. Figures 4a to 4c As shown in , the positive electrode tab 125 and the negative electrode tab 124 may be disposed on the same surface of the positive electrode plate 122 and the negative electrode plate 121, or may be disposed on opposite surfaces of the positive electrode plate 122 and the negative electrode plate 121, respectively. That is, in the present invention, the surfaces to which the positive electrode tab 125 and the negative electrode tab 124 are attached are not limited to the two surfaces of the positive electrode plate 122 and the negative electrode plate 121, each made of foil.

[0081] In addition, the positive electrode tab 125 and the negative electrode tab 124 may be arranged to be aligned on the same line in the longitudinal direction of the wound electrode assembly 420. In addition, the positive electrode tab 125 and the negative electrode tab 124 may be arranged not to overlap each other in the longitudinal direction of the wound electrode assembly 420. This is to prevent a reduction in the winding roundness rate, which may occur when the positive electrode tab 125 and the negative electrode tab 124, which are thicker than the positive electrode plate 122 and the negative electrode plate 121, overlap each other in the longitudinal direction of the electrode assembly 220. In the electrode assembly 420, the positive electrode tab 125 may be arranged inside the negative electrode plate 121 relative to the separator 123 at the portion to which the negative electrode tab 124 is attached. The positive electrode tab 125 may be made of an aluminum material, but the present invention is not limited thereto.

[0082] In addition, the positive electrode collector plate 122a is provided with a first positive electrode uncoated portion 122c on which the positive electrode coating 122b is not formed at both sides, which are one side in the winding direction x and the opposite side in the winding direction x of one surface of the positive electrode collector plate 122a to which the positive electrode tab 125 is attached. That is, the positive electrode tab 125 is attached to one surface of the positive electrode collector plate 122a of the positive electrode plate 122 so as to be spaced apart from the positive electrode coating 122b. In addition, on the other surface which is the opposite surface of the one surface on which the positive electrode tab 125 is attached, the positive electrode plate 122 is further provided with a second positive electrode uncoated portion 122d on which the positive electrode coating 122b is not formed on an area corresponding to the area corresponding to the positive electrode tab 125 and the area on which the first positive electrode uncoated portion 122c is provided.

[0083] In addition, in the wound electrode assembly 420, on the positive electrode plate 122 as the closest to the negative electrode plate 121, on the inner and outer sides of the portion to which the negative electrode tab 124 is attached, the positive electrode plate 122 is provided with a positive electrode half-coating portion 422e on the positive electrode plate 122 to which the positive electrode tab 125 is not attached. Here, the positive electrode half-coating portion 422e means that the positive electrode coating 122b is formed only on one surface of the positive electrode collector plate 122a, and the opposite surface is provided as an uncoated portion on which the positive electrode coating 122b is not formed. In the wound electrode assembly 420, the positive electrode half-coating portion 422e is provided on the positive electrode plate 122 as the closest to the negative electrode plate 121, on the outer side of the portion to which the negative electrode tab 124 is attached.

[0084] Here, the inner side means the positive electrode plate disposed in the direction of the winding center c relative to the negative electrode plate 121, and the outer side means the positive electrode plate disposed in the direction of the outermost side o relative to the negative electrode plate 121. In addition, the positive electrode half-coated portion 422e may be formed to have a width greater than that of each of the first negative electrode uncoated portion 121c and the second negative electrode uncoated portion 121d in the direction perpendicular to the longitudinal direction. This is to prevent misalignment of the positive electrode tab 125, the negative electrode tab 124, and the positive electrode half-coated portion 422e when the electrode assembly 420 is wound.

[0085] In addition, the positive electrode half-coating portion 422e is Fig. 9 and Fig.10 12 is shown as having a positive electrode coating portion 122b formed on one surface to which the positive electrode tab 125 is attached and an uncoated portion formed on the other surface as the opposite surface, and vice versa. As described above, the positive electrode plate 122 forms a positive electrode semi-coating portion 422e at a position corresponding to the negative electrode tab 124 to prevent lithium from being deposited when the secondary battery is overcharged. Fig.11 , showing another embodiment according to the present invention Figure 1a to Figure 1d 2 is a cross-sectional view of a state before an electrode assembly 120 of a secondary battery is wound. Fig.11 The negative electrode plate 121, the positive electrode plate 122, the separator 123, the negative electrode tab 124, the positive electrode tabs 125 and 129, etc. are shown. However, for the convenience of explanation, these are not shown in actual proportion. For example, it should be noted that the thickness of the negative electrode tab 124 or the positive electrode tabs 125 and 129 may be thicker and wider, or the positive electrode uncoated portions 122c and 122d may be formed longer. In addition, referring to Fig.12 , showing Fig.11 1 is an enlarged transverse cross-sectional view of a portion of the transverse cross-sectional view of the electrode assembly in the wound state shown in FIG. Fig.11 and Fig.12 The configurations of the secondary battery and the electrode assembly of the present invention are described in more detail.

[0086] In the negative electrode plate 121 of the electrode assembly 120, a negative electrode coating 121b as an active material made of a transition metal oxide is coated on both sides of a negative electrode collector 121a, which is a plate-shaped metal foil made of copper (Cu) or nickel (Ni). A negative electrode tab 124 is attached to one surface of the negative electrode collector 121a. The negative electrode tab 124 may be partially welded and attached to the negative electrode collector 121a, and may protrude downward by a predetermined length in the longitudinal direction of the electrode assembly 120, for example (see FIG. Figure 1c ). However, the negative electrode tab 124 may not necessarily protrude downward with respect to the longitudinal direction of the electrode assembly 120, but may protrude in another direction as needed.

[0087] The negative electrode plate 121 may be based on Figure 2 The drawing direction is from left to right (in Figure 2 In the following, the x direction is referred to as the winding direction, and for convenience, based on Figure 2 In the drawing direction of FIG. 1 , the left end of the negative electrode plate 121 is referred to as the front end of the negative electrode plate 121, and the right end is referred to as the rear end of the negative electrode plate 121. In the state where the winding is completed, the front end of the negative electrode plate 121 is in contact with the core region (see FIG. 1 ). Figure 1d ).

[0088] In addition, in the negative electrode plate 121, the negative electrode collector 121a is exposed through the main first negative electrode uncoated portion 121c and the main second negative electrode uncoated portion 121d (i.e., the main negative electrode uncoated portions 121c and 121d) in a state where the negative electrode coating 121b is not formed on the negative electrode collector 121a. The negative electrode tab 124 may be attached to the negative electrode collector 121a in the main negative electrode uncoated portions 121c and 121d, and Fig.11 , specifically, the negative electrode tab 124 is shown as being attached to the main first negative electrode uncoated portion 121c. The width of the main first negative electrode uncoated portion 121c in the winding direction may be greater than the width of the negative electrode tab 124 in the same direction, and thus, even after the negative electrode tab 124 is attached, a portion of the negative electrode current collector 121a may be exposed. Fig.11 The main negative electrode uncoated portions 121c and 121d are respectively formed on the bottom and top surfaces of the negative electrode collector 121a, but the main first negative electrode uncoated portion 121c may be formed only on the surface to which the negative electrode tab 124 is attached of the two surfaces of the negative electrode collector 121a.

[0089] In the transverse section of the wound electrode assembly 120, the negative electrode tab 124 may be disposed at any position between 1 / 5 and 4 / 5 of the transverse section radius r, where the transverse section radius r is the length between the winding center c and the outermost side o (see Figure 1d ). Preferably, the negative electrode tab 124 may be disposed at the approximate center of the transverse cross-sectional radius r. The negative electrode tab 124 may be made of copper or nickel, but is not limited thereto, and may be made of other materials.

[0090] The sub-negative electrode uncoated portion 128 is formed at the rear end of the negative electrode plate 121. As described again below, the sub-negative electrode uncoated portion 128 can be directly attached to the inner surface of the housing 110 and can therefore be used as an electrode. Therefore, the negative electrode plate 121 can have one negative electrode tab 124 and a sub-negative electrode uncoated portion 128 to act as if there are two negative electrode tabs, thereby minimizing the total number of electrode tabs. In the sub-negative electrode uncoated portion 128, the negative electrode coating 121b is shown as not being formed on both sides of the negative electrode collector 121a, but as required, the negative electrode coating may only not be formed on the outer surface of the negative electrode collector 121a (i.e., the surface facing the outermost side o in the winding state).

[0091] The positive electrode plate 122 is coated with a positive electrode coating 122b on both surfaces of a positive electrode current collector 122a, the positive electrode coating 122b being an active material made of a transition metal oxide, and the positive electrode current collector 122a being a plate-shaped metal foil made of aluminum (Al). Positive electrode tabs 125 and 129 are attached to one surface of the positive electrode current collector 122a. The positive electrode tabs 125 and 129 may be welded and attached to the positive electrode current collector 122a, and may protrude upward by a predetermined length based on the longitudinal direction of the electrode assembly 120 (see FIG. Figure 1c ). However, as in the case of the negative electrode tab 124 described above, the direction in which the positive electrode tabs 125 and 129 protrude may also be changed as desired. For example, the negative electrode tab 124 may protrude upward, and the positive electrode tabs 125 and 129 may protrude downward, or the negative electrode tab 124 and the positive electrode tabs 125 and 129 may protrude in the same direction.

[0092] The positive electrode tabs 125 and 129 are illustrated as being divided into a first positive electrode tab 125 and a second positive electrode tab 129. Here, the second positive electrode tab 129 differs from the first positive electrode tab 125 only in position, and unless otherwise described, the description of the first positive electrode tab 125 may be equally applicable to the second positive electrode tab 129.

[0093] In the transverse section of the wound electrode assembly 120, the first positive electrode tab 125 may be disposed at any position between 1 / 5 and 4 / 5 of the transverse section radius r, the transverse section radius r being the length between the winding center c and the outermost side o. Preferably, the first positive electrode tab 125 may be disposed at the approximate center of the transverse section radius r. Of course, it may be applied to the second positive electrode tab 129 in the same manner. This consideration regarding the position of the first positive electrode tab 125 is for the same reasons as described for the negative electrode tab 124. In addition, the positive electrode tab 125 may be disposed on each surface facing the negative electrode tab 124, while the separator 123 is between each of the negative electrode collector 121a and the positive electrode collector 122a of the wound electrode assembly 120. However, the present invention is not limited thereto. That is, the positive electrode tab 125 and the negative electrode tab 124 may be disposed on different surfaces of the negative electrode collector 121a and the positive electrode collector 122a, respectively. That is, in the present invention, the surfaces to which the positive electrode tab 125 and the negative electrode tab 124 are attached among the two surfaces of the negative electrode collector 121 a and the positive electrode collector 122 a each having the form of a foil are not limited.

[0094] In addition, although Fig.12 1 shows an example in which the first positive electrode tab 125 is disposed closer to the center c than the negative electrode tab 124 relative to the separator 123 in the wound state, but the first positive electrode tab 125 may also be disposed closer to the outermost side o than the negative electrode tab 124, and Fig.13 An example of the above structure is shown in FIG.

[0095] In the positive electrode plate 122, a main first positive electrode uncoated portion 122c and a main second positive electrode uncoated portion 122d on which the positive electrode coating 122b is not formed (i.e., main positive electrode uncoated portions 122c and 122d) are formed in the positive electrode collector 122a to which the first positive electrode tab 125 is attached. That is, the first positive electrode tab 125 may be attached to the positive electrode collector 122a in the main first positive electrode uncoated portion 122c, and the width of the main first positive electrode uncoated portion 122c in the winding direction is greater than the width of the first positive electrode tab 125 in the same direction, and therefore, a portion of the positive electrode collector 122a may be exposed even after the first positive electrode tab 125 is attached. Although in Fig.11 In the present invention, main positive electrode uncoated portions 122c and 122d are formed on the bottom and top surfaces of the positive electrode collector 122a, respectively, but the main first positive electrode uncoated portion 122c may be formed only on the surface to which the positive electrode tab 125 is attached, of the two surfaces of the positive electrode collector 122a.

[0096] In addition, the main second positive electrode uncoated portion 122d may be formed to extend toward the rear end in the winding direction x. Fig.11 As shown in , the main second positive electrode uncoated portion 122d formed on the bottom surface of the positive electrode collector 122a may extend a predetermined length in the winding direction x from the region to which the first positive electrode tab 125 is attached, and thus, a positive electrode half-coated portion 122e on which the positive electrode coating 122b is not formed may be formed. Preferably, the positive electrode half-coated portion 122e may be disposed at a position corresponding to the first positive electrode tab 125 before one turn from the portion to which the first positive electrode tab 125 is attached in the winding state. In other words, in the winding state, the positive electrode half-coated portion 122e may be positioned on the same straight line as the first positive electrode tab 125 in the radius r direction. As described above, instead of the main second positive electrode uncoated portion 122d located on the bottom surface of the positive electrode collector 122a, the main first positive electrode uncoated portion 122c located on the top surface may extend in the winding direction x to form a positive electrode half-coated portion, or both surfaces may extend in the winding direction x to form a positive electrode half-coated portion on each of the two surfaces. Specifically, the former may be disposed at a position corresponding to the first positive electrode tab 125 one turn ahead of the portion to which the first positive electrode tab 125 is attached in a wound state. The directions of the main positive electrode uncoated portions 122c and 122d may not be as shown in FIG. Fig.11 In the example of FIG. 1 , the first positive electrode tab 125 is not extended toward the rear end relative to the winding direction x, but toward the front end. Even in this case, in the wound state, it is preferred that the positive electrode half-coated portion caused by the first positive electrode uncoated portions 122c and 122d is arranged on the same straight line as the first positive electrode tab 125 in the radius r direction.

[0097] The second positive electrode tab 129 is disposed to be spaced apart from the first positive electrode tab 125 in the winding direction x. A sub-positive electrode uncoated portion for attaching the second positive electrode tab 129 may be formed, and the sub-positive electrode uncoated portion may be substantially the same as the first positive electrode uncoated portions 122c and 122d. That is, a positive electrode semi-coated portion may also be formed around the second positive electrode tab 129.

[0098] exist Fig.11 In the example shown in , in the wound state, when the positive electrode half-coated portion 122e caused by the main second positive electrode uncoated portion 122d and the first positive electrode tab 125 are arranged on the same straight line in the radius r direction, this can help suppress lithium deposition during overcharging.

[0099] Reference Fig.14 , showing Figure 1a to Figure 1d, which is a cross-sectional view of another example of a state before the electrode assembly of a secondary battery is wound. Fig.15 , showing Fig.14 An enlarged cross-sectional view of a partial enlarged transverse cross-sectional view of the electrode assembly shown in FIG. 1 after winding.

[0100] As mentioned above, Fig.14 and Fig.15 The configurations of the case 110 of the secondary battery, the negative electrode plate 121 of the electrode assembly 120, the separator 123 of the electrode assembly 120, and the cap assembly 130 shown in FIG. 1 may be the same as those of Figure 1a to Figure 1d The configuration of the secondary battery 100 shown in FIG. 1 is the same as that of the secondary battery 100 shown in FIG. 1 . Therefore, the configuration of the positive electrode plate 122 of the electrode assembly 120 of the secondary battery will be referred to below. Figure 1a to Figure 1d , Fig.14 and Fig.15 To mainly describe the differences.

[0101] In the positive electrode plate 122, the positive electrode half-coated portion 222e may be formed to be spaced apart from the main second positive electrode uncoated portion 122d. The positive electrode half-coated portion 222e may be disposed only between the main positive electrode uncoated portion and the secondary positive electrode uncoated portion, but may be disposed closer to the main positive electrode uncoated portion. More preferably, the positive electrode half-coated portion 222e may be disposed at a position corresponding to the first positive electrode tab 125 before starting one turn from each of the main positive electrode uncoated portions 122c and 122d in a wound state. In this state, it may correspond to the result of intermittently forming the positive electrode coating 122b in the middle of the main second positive electrode uncoated portion 122d, where in the above reference Fig.11 In the illustrated embodiment, the positive electrode half-coating portion 222e extends in the winding direction x to form the positive electrode half-coating portion 122e. This can have the effect of increasing the length of the section forming the positive electrode coating 122b on the entire positive electrode plate 122, and the designer can make various choices so that the first positive electrode tab 125 and the positive electrode half-coating portion 222e are arranged on the same straight line in the radial direction according to the thickness of the electrode assembly, the size of the wound electrode assembly in the radial direction, etc. Fig.14 and Fig.15 , the positive electrode half-coated portion 222e may be exemplified as being formed only on the bottom surface based on the drawing direction of the positive electrode current collector 122a, but may be formed on the opposite surface instead of this configuration, for example, may be formed on both surfaces. In another embodiment not shown, the positive electrode half-coated portion 222e may be disposed on the front end instead of the main positive electrode uncoated portions 122c and 122d, and in this case, the positive electrode half-coated portion 222e may be disposed to correspond to the first positive electrode tab 125 before one turn from the main positive electrode uncoated portions 122c and 122d. As previously described with reference to Fig.12 and Fig.13 described, although Fig.15 An example is shown in which the first positive electrode tab 125 is disposed closer to the center portion c than the negative electrode tab 124 with respect to the separator 123 in the wound state, but the first positive electrode tab 125 may be disposed closer to the outermost side o than the negative electrode tab 124 .

Claims

1. An electrode assembly, comprising: A positive electrode plate, comprising a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector, wherein a positive electrode uncoated portion on which the positive electrode active material is not coated is formed in the positive electrode current collector; A negative electrode plate, comprising a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector, wherein a negative electrode uncoated portion not coated with the negative electrode active material is formed in the negative electrode current collector; A separator, disposed between the positive electrode plate and the negative electrode plate; a positive electrode tab electrically connected to the positive electrode current collector of the positive electrode plate; and a negative electrode tab electrically connected to the negative electrode current collector of the negative electrode plate, wherein the positive electrode plate, the negative electrode plate and the separator are wound in a sequentially stacked state, The positive electrode uncoated portion is provided between the front end and the rear end of the positive electrode plate in the winding direction, the positive electrode tab being attached to the positive electrode current collector on the positive electrode uncoated portion, The negative electrode uncoated portion includes a main negative electrode uncoated portion and a secondary negative electrode uncoated portion, the main negative electrode uncoated portion is formed between the front end and the rear end of the negative electrode plate in the winding direction, and the secondary negative electrode uncoated portion is formed on the rear end of the negative electrode plate, The negative electrode tab is disposed on the uncoated portion of the main negative electrode, and A positive electrode half-coating portion is formed at a position of the positive electrode plate corresponding to the negative electrode tab, the positive electrode half-coating portion being a portion where the positive electrode active material is formed only on one surface of the positive electrode collector.

2. The electrode assembly according to claim 1, wherein: The positive electrode uncoated portion includes a main positive electrode uncoated portion and a sub-positive electrode uncoated portion, the main positive electrode uncoated portion and the sub-positive electrode uncoated portion are formed to be spaced apart from each other between the front end and the rear end of the positive electrode plate in the winding direction, and The positive electrode tab includes a first positive electrode tab and a second positive electrode tab, and the first positive electrode tab and the second positive electrode tab are disposed on the main positive electrode uncoated portion and the sub positive electrode uncoated portion, respectively.

3. The electrode assembly according to claim 2, wherein: The primary positive electrode uncoated portion is disposed closer to the front end of the positive electrode plate than the secondary positive electrode uncoated portion, and The main positive electrode uncoated portion extends to a width greater than that of the first positive electrode tab in the winding direction to form the positive electrode half-coated portion, wherein the positive electrode half-coated portion is arranged one circle inside the first positive electrode tab in the wound state.

4. The electrode assembly according to claim 2, wherein: The primary positive electrode uncoated portion is disposed closer to the front end of the positive electrode plate than the secondary positive electrode uncoated portion, and The main positive electrode uncoated portion extends to a width greater than that of the first positive electrode tab in the winding direction to form the positive electrode half-coated portion, wherein the positive electrode half-coated portion is arranged one circle outside the first positive electrode tab in the wound state.

5. The electrode assembly according to claim 2, wherein: The positive electrode half-coated portion is located at a position spaced apart from the main positive electrode uncoated portion in the winding direction so as to be adjacent thereto.

6. The electrode assembly according to claim 5, wherein: The positive electrode half-coated portion is disposed at an opposite front end side compared to the main positive electrode uncoated portion, and the positive electrode half-coated portion is disposed one turn inside the first positive electrode tab in the wound state.

7. The electrode assembly according to claim 5, wherein: The positive electrode half-coated portion is disposed at an opposite rear end side compared to the main positive electrode uncoated portion, and the positive electrode half-coated portion is disposed one turn outside the first positive electrode tab in the wound state.

8. The electrode assembly according to claim 2, wherein: The first positive electrode tab and the second positive electrode tab are arranged on a straight line in the radial direction in the wound state.

9. The electrode assembly according to claim 1, wherein: The positive electrode tab and the negative electrode tab are disposed in the wound state in a region corresponding to 1 / 5 to 4 / 5 of the radius of the transverse cross section.

10. The electrode assembly according to claim 9, wherein: The positive electrode tab and the negative electrode tab are disposed on the same line in the longitudinal direction of the electrode assembly in the wound state, wherein a lower portion of the positive electrode tab and an upper portion of the negative electrode tab are disposed not to overlap each other.

11. A secondary battery, comprising: The electrode assembly according to claim 1; a housing configured to accommodate the electrode assembly and the electrolyte in an inner space of the housing; as well as a cover plate coupled to an upper portion of the housing to seal the housing, Wherein, the uncoated portion of the sub-negative electrode is attached to the inner surface of the casing.

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