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, wherein the capacity of the negative electrode coating can be prevented from being unnecessarily increased by adjusting at least one of the loading degree of the positive electrode coating and the loading degree of the negative electrode coating, and a minimum positive electrode to negative electrode capacity ratio can be maintained according to the number of winding turns of the electrode assembly to minimize lithium precipitation.

Description

Technical Field

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

[0002] Secondary batteries are power storage systems that provide excellent energy density to convert electrical energy into chemical energy to store chemical energy. When compared to non-rechargeable primary batteries, secondary batteries are rechargeable and widely used in IT devices such as smart phones, cellular phones, laptops, tablet PCs, etc. Recently, in order to prevent environmental pollution, interest in electric vehicles has increased, and therefore, high-capacity secondary batteries are being used in electric vehicles. Such secondary batteries need to have characteristics such as high density, high output, and stability.

[0003] 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

[0004] Technical issues

[0005] The present invention provides an electrode assembly and a secondary battery including the electrode assembly, in which at least one of the load degree of the positive electrode coating and the load degree of the negative electrode coating is adjusted to prevent the capacity of the negative electrode coating from increasing unnecessarily, and a minimum negative electrode to positive electrode capacity ratio is maintained according to the number of winding turns of the electrode assembly to minimize lithium precipitation.

[0006] The present invention also provides an electrode assembly and a secondary battery including the same, in which a capacity ratio of a negative electrode to a positive electrode is optimally maintained according to the number of turns of the electrode assembly to increase an output of the capacity of the electrode assembly.

[0007] Technical Solution

[0008] An electrode assembly according to an embodiment of the present invention includes: a negative electrode plate, on which a negative electrode coating is formed on both surfaces of a negative electrode collector; a positive electrode plate, on which a positive electrode coating is formed on both surfaces of a positive electrode collector; and a separator, disposed between the positive electrode plate and the negative electrode plate, wherein the positive electrode coating includes: a first positive electrode coating formed on a front end region of a first surface of the positive electrode collector; a second positive electrode coating formed on a front end region of a second surface, the second surface being an opposite surface of the first surface of the positive electrode collector; a third positive electrode coating formed on a rear end region of the first surface of the positive electrode collector; and a fourth positive electrode coating formed on a rear end region of the second surface of the positive electrode collector, wherein a load level of the first positive electrode coating is greater than a load level of the second positive electrode coating, and each of a load level of the third positive electrode coating and a load level of the fourth positive electrode coating is less than a load level of the first positive electrode coating and greater than a load level of the second positive electrode coating.

[0009] The sum of the loading degree of the first positive electrode coating layer and the loading degree of the second positive electrode coating layer may be equal to or less than the sum of the loading degree of the third positive electrode coating layer and the loading degree of the fourth positive electrode coating layer.

[0010] The negative electrode coating may include: a first negative electrode coating formed on a front end region of a first surface of the negative electrode collector; a second negative electrode coating formed on a front end region of a second surface, the second surface being an opposite surface to the first surface of the negative electrode collector; a third negative electrode coating formed on a rear end region of the first surface of the negative electrode collector; and a fourth negative electrode coating formed on a rear end region of the second surface of the negative electrode collector.

[0011] The loading degree of the first negative electrode coating layer and the loading degree of the third negative electrode coating layer may be the same, and

[0012] The loading degree of the second negative electrode coating layer and the loading degree of the fourth negative electrode coating layer may be the same and smaller than the loading degree of the first negative electrode coating layer.

[0013] The loading degree of the first negative electrode coating may be greater than that of the second negative electrode coating, and the loading degree of the third negative electrode coating and the loading degree of the fourth negative electrode coating may be less than that of the first negative electrode coating and greater than that of the second negative electrode coating.

[0014] The sum of the loading degree of the first negative electrode coating and the loading degree of the second negative electrode coating may be the same as the sum of the loading degree of the third negative electrode coating and the loading degree of the fourth negative electrode coating.

[0015] The positive electrode plate may further include: a first positive electrode uncoated portion, on the first surface, the first positive electrode coating and the third positive electrode coating are spaced apart from each other so that the positive electrode coating is not formed on the first positive electrode uncoated portion; a second positive electrode uncoated portion, on the second surface, the second positive electrode coating and the fourth positive electrode coating are spaced apart from each other so that the positive electrode coating is not formed on the second positive electrode uncoated portion; and a positive electrode tab attached to either the first positive electrode uncoated portion or the second positive electrode uncoated portion.

[0016] The negative electrode plate may further include: a first negative electrode uncoated portion, on a first surface, the first negative electrode coating and the third negative electrode coating are spaced apart from each other so that the negative electrode coating is not formed on the first negative electrode uncoated portion; a second negative electrode uncoated portion, on a second surface, the second negative electrode coating and the fourth negative electrode coating are spaced apart from each other so that the negative electrode coating is not formed on the second negative electrode uncoated portion; and a negative electrode tab attached to either the first negative electrode uncoated portion or the second negative electrode uncoated portion.

[0017] In addition, an electrode assembly according to an embodiment of the present invention includes: a negative electrode plate, on which a negative electrode coating is formed on both surfaces of a negative electrode collector; a positive electrode plate, on which a positive electrode coating is formed on both surfaces of a positive electrode collector; and a separator, disposed between the positive electrode plate and the negative electrode plate, wherein the negative electrode coating includes: a first negative electrode coating formed on a front end region of a first surface of the negative electrode collector; a second negative electrode coating formed on a front end region of a second surface, the second surface being an opposite surface of the first surface of the negative electrode collector; a third negative electrode coating formed on a rear end region of the first surface of the negative electrode collector; and a fourth negative electrode coating formed on a rear end region of the second surface of the negative electrode collector, wherein a load level of the first negative electrode coating is greater than a load level of the second negative electrode coating, and each of a load level of the third negative electrode coating and a load level of the fourth negative electrode coating is less than a load level of the first negative electrode coating and greater than a load level of the second negative electrode coating.

[0018] The sum of the loading degree of the first negative electrode coating and the loading degree of the second negative electrode coating may be equal to or greater than the sum of the loading degree of the third negative electrode coating and the loading degree of the fourth negative electrode coating.

[0019] The positive electrode coating may include: a first positive electrode coating formed on a front end region of a first surface of a positive electrode collector; a second positive electrode coating formed on a front end region of a second surface, the second surface being an opposite surface to the first surface of the positive electrode collector; a third positive electrode coating formed on a rear end region of the first surface of the positive electrode collector; and a fourth positive electrode coating formed on a rear end region of the second surface of the positive electrode collector, wherein a loading degree of the first positive electrode coating may be the same as a loading degree of the third positive electrode coating, and a loading degree of the second positive electrode coating and a loading degree of the fourth positive electrode coating may be the same and less than a loading degree of the first positive electrode coating.

[0020] Beneficial Effects

[0021] In an electrode assembly according to an embodiment of the present invention and a secondary battery including the electrode assembly, at least one of the load degree of the positive electrode coating and the load degree of the negative electrode coating can be adjusted to prevent the capacity of the negative electrode coating from increasing unnecessarily, and a minimum negative electrode to positive electrode capacity ratio is maintained according to the number of winding turns of the electrode assembly to minimize lithium precipitation.

[0022] That is, embodiments of the present invention may provide an electrode assembly and a secondary battery including the same, in which a negative electrode to positive electrode capacity ratio is optimally maintained according to the number of turns of the electrode assembly to increase an output of the capacity of the electrode assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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.

[0024] Figure 2 It is shown Figure 1a to Figure 1d 2 is an exploded perspective view of a state of an electrode assembly of a secondary battery before being wound.

[0025] Figure 3 is a view showing the result of a capacity ratio of a negative electrode to a positive electrode according to the number of winding turns of an electrode assembly according to a comparative example of the present invention.

[0026] Figure 4 : is a view showing the result of the capacity ratio of the negative electrode to the positive electrode according to the number of winding turns of the electrode assembly according to the example of Embodiment 1 of the present invention.

[0027] Figure 5 : is a view showing the result of the capacity ratio of the negative electrode to the positive electrode according to the number of winding turns of the electrode assembly according to another example of Embodiment 1 of the present invention.

[0028] Figure 6 : is a view showing the result of the capacity ratio of the negative electrode to the positive electrode according to the number of winding turns of the electrode assembly according to the example of Embodiment 2 of the present invention.

[0029] Figure 7 : is a view showing the result of the capacity ratio of the negative electrode to the positive electrode according to the number of winding turns of the electrode assembly according to another example of Embodiment 2 of the present invention.

[0030] Figure 8 : is a view showing the result of the capacity ratio of the negative electrode to the positive electrode according to the number of winding turns of the electrode assembly according to the example of Embodiment 3 of the present invention.

[0031] Fig. 9 : is a view showing the result of the capacity ratio of the negative electrode to the positive electrode according to the number of winding turns of the electrode assembly according to another example of Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0032] 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.

[0033] In addition, in the accompanying drawings, the sizes of layers and regions may be exaggerated for clarity. The same reference numerals always refer to 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 between component A and component B.

[0034] 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 particular 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 groups mentioned, nor exclude the existence or addition of one or more other different shapes, quantities, processes, operations, members, elements and / or groups of these. The term "and / or" used herein includes any combination and all combinations of one or more of the related listed items.

[0035] 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. These terms do not refer to a specific order, upper and lower or superiority, and are 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 refer to the second component, second component, second region, second layer or second part.

[0036] For ease of description, spatially relative terms such as "below", "under", "down", "above", "on", etc. are used herein to describe the relationship between an element or feature as shown in the figure and another (other) element or feature. 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 accompanying drawings are turned over, 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".

[0037] 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 cross-sectional view showing a secondary battery 100 according to an embodiment of the present invention. Here, the longitudinal cross-section is a section cut along the longitudinal direction of the secondary battery 100, and the cross-sectional view is a section cut along the winding direction of the secondary battery.

[0038] 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 .

[0039] The housing 110 includes a circular bottom 111 and a side 112 extending upward from the bottom 111 by a predetermined length. Here, the secondary battery 100 may be a cylindrical secondary battery formed by winding the electrode assembly 120. During the process of manufacturing the secondary battery 100, the upper portion of the housing 110 is open. Therefore, during the process of assembling the secondary battery, the electrode assembly 120 may be inserted into the housing 110 together with the electrolyte. The housing 110 may be made of steel, steel alloy, aluminum, aluminum alloy, or their equivalents, but its material is not limited thereto. In addition, in the housing 110, an inwardly concave curling portion 113 may be formed at the lower portion of the housing 110 relative to the cap assembly 140 to prevent the cap assembly 130 from being detached from the outside, and an inwardly bent crimping portion 114 may be formed at the upper portion of the housing 110.

[0040] The electrode assembly 120 is accommodated in the case 110 together with an electrolyte. Here, the electrolyte is an organic liquid containing a salt 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.

[0041] The electrode assembly 120 includes a negative electrode plate 121 coated with a negative active material, a positive electrode plate 122 coated with a positive active material, and a separator 125 interposed 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 move only lithium ions. The negative electrode plate 121, the positive electrode plate 122, and the separator 125 are wound into a substantially cylindrical shape. In addition, in the negative electrode plate 121, a negative electrode tab 126 protruding downward by a predetermined length may be attached to a positive electrode tab 127 protruding upward by a predetermined length, but vice versa.

[0042] In addition, refer to Figure 2 , showing Figure 1a to Figure 1d FIG. 1 is an exploded perspective view of an electrode assembly of a secondary battery before winding. Figure 2 The configurations of a secondary battery and an electrode assembly according to the present invention are described in detail.

[0043] First, in the negative electrode plate 121 of the electrode assembly 120, a negative electrode coating 123 as an active material made of a transition metal oxide is applied on both sides of a negative electrode collector 121a, which is a plate-shaped metal foil made of copper (Cu) or nickel (Ni). The negative electrode coating 123 may include a first negative electrode coating 123a formed on a front end region X as a region adjacent to a front end Ra of a first surface 121ax of the negative electrode collector 121a, a second negative electrode coating 123b formed on a front end region X of a second surface 121ay opposite to the first surface 121ax, a third negative electrode coating 123c formed on a rear end region Y adjacent to a rear end Rb of the first surface 121ax of the negative electrode collector 121a, and a fourth negative electrode coating 123d formed on the rear end region Y of the second surface 121ay. Here, the front end Ra may be an end portion at which the negative electrode plate 121 starts to be wound together with the positive electrode plate 211 and the separator 213 , and the rear end Rb may be an end portion at which the winding is terminated.

[0044] The loading degree of the first negative electrode coating 123a may be greater than or equal to the loading degree of the second negative electrode coating 123b. Here, the loading degree refers to the coating amount or weight of the coating per unit area.

[0045] In addition, the loading degree of the third negative electrode coating 123c may be greater than or equal to the loading degree of the fourth negative electrode coating 123d. In addition, the sum of the loading degree of the first negative electrode coating 123a and the loading degree of the second negative electrode coating 123b may be greater than or equal to the sum of the loading degree of the third negative electrode coating 123c and the loading degree of the fourth negative electrode coating 123d.

[0046] The first negative electrode coating 123a, the second negative electrode coating 123b, the third negative electrode coating 123c, and the fourth negative electrode coating 123d may be maintained at a minimum negative electrode to positive electrode capacity ratio according to the number of turns of the wound electrode assembly 120 to minimize the amount of lithium precipitation. As described above, the negative electrode to positive electrode capacity ratio may be optimally maintained according to the number of turns of the electrode assembly 120 to improve the efficiency of the capacity of the electrode assembly 120. The above-mentioned load degree of the negative electrode coating 123 will be described in detail below.

[0047] In addition, the first negative electrode coating 123a and the third negative electrode coating 123c may be spaced apart from each other by a predetermined distance. That is, the first negative electrode coating 123a and the third negative electrode coating 123c may be spaced apart from each other on the first surface 121ax of the negative electrode collector 121a, and the first negative electrode non-coating portion 121b on which the negative electrode coating 123 is not formed may be disposed on the first surface 121ax of the negative electrode collector 121a.

[0048] In addition, the second negative electrode coating 123b and the fourth negative electrode coating 123d may be spaced apart from each other by a predetermined distance. That is, the second negative electrode coating 123b and the fourth negative electrode coating 123d may be spaced apart from each other on the second surface 121ay of the negative electrode collector 121a, and the second negative electrode uncoated portion 121c on which the negative electrode coating 123 is not formed may be disposed on the second surface 121ay of the negative electrode collector 121a. Here, the first negative electrode uncoated portion 121b and the second negative electrode uncoated portion 121c may be disposed at the same position relative to the negative electrode collector 121a. That is, the negative electrode collector 121a may include the second negative electrode uncoated portion 121c on the surface opposite to the first surface 121ax on which the first negative electrode uncoated portion 121b is formed.

[0049] In addition, the first negative electrode coating 123a and the second negative electrode coating 123b may include two or more coating patterns, respectively. When two coating patterns are provided, the two coating patterns (ie, a pattern adjacent to the front end Ra and a pattern adjacent to the rear end Rb) may be spaced apart from each other.

[0050] The negative electrode tab 126 may be attached to any one of the first negative electrode non-coating portion 121b of the first surface 121ax and the second negative electrode non-coating portion 121c of the second surface 121ay in the negative electrode collector 121a. Figure 2The negative electrode tab 126 is shown attached to the first negative electrode non-coated portion 121b of the negative electrode collector 121a, but in the present invention, the surface to which the negative electrode tab 126 is attached is not limited thereto. The negative electrode tab 126 may be partially welded and attached to the negative electrode collector 121a and protrude downward by a predetermined length in the longitudinal direction of the electrode assembly 120.

[0051] The negative electrode tab 126 may be disposed at the approximate center of the cross-sectional radius r in the cross-sectional view of the wound electrode assembly 120, the cross-sectional radius r being the length between the winding center c and the outermost portion o. In addition, the negative electrode tab 126 may be disposed on the first surface 121ax or the second surface 121ay of the end region adjacent to the front end Ra or the rear end Rb of the negative electrode collector 121a. The negative electrode tab 126 may be made of a copper or nickel material, but the present invention is not limited thereto. In addition, the front end Ra may be adjacent to the winding center c in the wound electrode assembly 120, and the rear end Rb may be disposed at the outermost portion o in the wound electrode assembly 120. Of course, an uncoated portion on which the negative electrode coating 123 is not formed may be disposed on the negative electrode collector 121a on which the negative electrode tab 126 is disposed.

[0052] The positive electrode plate 122 is coated with a positive electrode coating 124 which is an active material made of a transition metal oxide on both surfaces of a positive electrode collector 122 a which is a plate-shaped metal foil made of aluminum (Al).

[0053] The positive electrode coating 124 may include a first positive electrode coating 124a formed on a front end region X of a first surface 122ax of the positive electrode collector 122a, a second positive electrode coating 124b formed on a front end region X of a second surface 122ay opposite to the first surface 122ax, a third positive electrode coating 124c formed on a rear end region Y of the first surface 122ax of the positive electrode collector 122a, and a fourth positive electrode coating 124d formed on a rear end region Y of the second surface 122ay.

[0054] The loading degree of the first positive electrode coating 124a may be greater than or equal to that of the second positive electrode coating 124b. In addition, the loading degree of the third positive electrode coating 124c may be greater than or equal to that of the fourth positive electrode coating 124d.

[0055] In addition, the sum of the loading degree of the first positive electrode coating 124a and the loading degree of the second positive electrode coating 124b may be greater than or equal to the sum of the loading degree of the third positive electrode coating 124c and the loading degree of the fourth positive electrode coating 124d.

[0056] The first positive electrode coating 124a, the second positive electrode coating 124b, the third positive electrode coating 124c, and the fourth positive electrode coating 124d may be maintained at a minimum negative electrode to positive electrode capacity ratio according to the number of turns of the wound electrode assembly 120 to minimize the amount of lithium precipitation. As described above, the negative electrode to positive electrode capacity ratio may be optimally maintained according to the number of turns of the electrode assembly 120 to improve the efficiency of the capacity of the electrode assembly 120. The above-mentioned load degree of the positive electrode coating 124 will be described in detail below.

[0057] In addition, the first positive electrode coating 124a and the third positive electrode coating 124c may be spaced apart from each other by a predetermined distance. That is, the first positive electrode coating 124a and the third positive electrode coating 124c may be spaced apart from each other on the first surface 122ax of the positive electrode collector 122a, and the first positive electrode non-coating portion 122b on which the positive electrode coating 124 is not formed may be disposed on the first surface 122ax of the positive electrode collector 122a.

[0058] In addition, the second positive electrode coating 124b and the fourth positive electrode coating 124d may be spaced apart from each other by a predetermined distance. That is, the second positive electrode coating 124b and the fourth positive electrode coating 124d may be spaced apart from each other on the second surface 122ay of the positive current collector 122a, and the second positive electrode uncoated portion 122c on which the positive electrode coating 124 is not formed may be disposed on the second surface 122ay of the positive current collector 122a. Here, the first positive electrode uncoated portion 122b and the second positive electrode uncoated portion 122c may be disposed at the same position relative to the positive current collector 122a. That is, the positive current collector 122a may include a second positive electrode uncoated portion 122c on a surface opposite to the first surface 122ax on which the first electrode uncoated portion 122b is formed.

[0059] In addition, the first positive electrode coating layer 124a and the second positive electrode coating layer 124b may include two or more coating patterns, respectively. When two coating patterns are provided, the two coating patterns (ie, the pattern adjacent to the front end Ra and the pattern adjacent to the rear end Rb) may be spaced apart from each other.

[0060] The positive electrode tab 127 may be attached to any one of the first positive electrode non-coating portion 122b of the first surface 122ax and the second positive electrode non-coating portion 122c of the second surface 122ay in the positive electrode collector 122a. Figure 2 The state in which the positive electrode tab 127 is attached to the first positive electrode non-coated portion 122b of the positive electrode collector 122a is shown, but in the present invention, the surface to which the positive electrode tab 127 is attached is not limited thereto. The positive electrode tab 127 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.

[0061] The positive electrode tab 127 may be disposed at the approximate center of the cross-sectional radius r in the cross section of the wound electrode assembly 120, the cross-sectional radius r being the length between the winding center c and the outermost portion o. In addition, the positive electrode tab 127 may be disposed on the first surface 122ax or the second surface 122ay of the end region adjacent to the front end Ra or the rear end Rb of the positive electrode collector 122a. Of course, an uncoated portion on which the positive electrode coating 124 is not formed may be disposed on the positive electrode collector 122a on which the positive electrode tab 127 is disposed. The positive electrode tab 127 may be made of an aluminum material, but the present invention is not limited thereto.

[0062] In addition, the negative electrode tab 126 and the positive electrode tab 127 may be disposed on the same surface of the wound negative electrode plate 121 and the positive electrode plate 122, and may be disposed on opposite surfaces of the negative electrode plate 121 and the positive electrode plate 122. Here, the same surface may be a surface facing the winding center c in the wound electrode assembly 120 in the same manner, or may be a surface facing the outermost portion o in the same manner.

[0063] Hereinafter, the first surface 121ax of the negative electrode collector 121a and the first surface 122ax of the positive electrode collector 122a facing the outermost portion o of the wound electrode assembly 120 are referred to as outer surfaces, and the second surface 121ay of the negative electrode collector 121a and the second surface 122ay of the positive electrode collector 122a facing the winding center c are referred to as inner surfaces.

[0064] In addition, when the negative electrode tab 126 is attached to the opposite surface of the outer surface 122ax of the positive electrode collector 122a to which the positive electrode tab 127 is attached in the wound electrode assembly 120, it means that the negative electrode tab 126 is formed on the inner surface 121ay, and vice versa. That is, in the present invention, the surface to which the negative electrode tab 126 and the positive electrode tab 127 are attached is not limited to the two surfaces of each of the negative electrode plate 121 and the positive electrode plate 122 made of foil.

[0065] In addition, the negative electrode tab 126 of the electrode assembly 120 may be welded to the bottom 111 of the case 110. Therefore, the case 110 may be operated as a negative electrode. Of course, conversely, the positive electrode tab 127 may be welded to the bottom 111 of the case 110, and in this case, the case 110 may be operated as a positive electrode.

[0066] In addition, a first insulating plate 128 coupled to the case 110 and having a first hole 128a at the center thereof and a second hole 128b formed in the outer portion thereof may be placed between the electrode assembly 120 and the bottom 111. The first insulating plate 128 is used to prevent the electrode assembly 120 from electrically contacting the bottom 111 of the case 110. In particular, the first insulating plate 128 is used to prevent the positive plate 122 of the electrode assembly 120 from electrically contacting the bottom 111. Here, the first hole 128a is used to allow the gas to move upward quickly when a large amount of gas is generated due to an abnormality in the secondary battery, and the second hole 128b is used to allow the negative electrode tab 126 to pass through the second hole 128b so as 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 a substantially 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.

[0067] In addition, a second insulating plate 129 coupled to the case 110 and having a first hole 129a at the center thereof and a plurality of second holes 129b formed in the outer portion thereof may be interposed between the electrode assembly 120 and the cap assembly 130. The second insulating plate 129 is used to prevent the electrode assembly 120 from electrically contacting the cap assembly 130. In particular, the second insulating plate 129 is used to prevent the negative electrode plate 121 of the electrode assembly 120 from electrically contacting the cap assembly 130. Here, the first hole 129a is 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 129b is used to allow the positive electrode tab 127 to pass through the second hole 129b so as to be welded to the cap assembly 130. In addition, the remaining second holes 129b are used to allow the electrolyte to quickly flow into the electrode assembly 120 in the process of injecting the electrolyte. The electrolyte serves as a moving medium for lithium ions, which are generated by electrochemical reactions in the positive and negative plates inside the battery during charging and discharging.

[0068] 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 sub-plate 137 fixed to a lower portion of the lower cover 136 and electrically connected to the positive electrode tab 127, 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.

[0069] Here, the insulating gasket 138 is basically compressed 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 are used to discharge the internal gas to the outside when abnormal internal pressure occurs inside the housing 110. Of course, when the safety plate 133 is turned up by the internal pressure, the safety plate 133 is electrically separated from the sub-plate 137, and then, the safety plate 133 is torn to discharge the internal gas to the outside.

[0070] Hereinafter, various embodiments of the load degree of the negative electrode coating 123 and the load degree of the positive electrode coating 124 in the electrode assembly 120 of the present invention will be described in conjunction with comparative examples, through which the minimum negative electrode to positive electrode capacity ratio is maintained to minimize lithium precipitation and maximize the output of capacity. Here, the negative electrode to positive electrode capacity ratio that minimizes lithium precipitation may be about 1.05, but the present invention is not limited thereto. In addition, the case where the negative electrode to positive electrode capacity ratio is 1.05 refers to the case when the capacity of the positive electrode coating 124 is 1 and the capacity of the negative electrode coating 123 is 1.05.

[0071] Comparison examples

[0072] The loading degree of the first negative electrode coating 123a and the third negative electrode coating 123c is the same as A1, and the loading degree of the second negative electrode coating 123b and the fourth negative electrode coating 123d is the same as B1 and less than A1. That is, the loading degree of the negative electrode coating 123 formed on the inner surface 121ay of the negative electrode collector 121a may be constant, and the loading degree of the negative electrode coating 123 formed on the outer surface 121ax of the negative electrode collector 121a may be constant.

[0073] The loading degree of the first positive electrode coating 124a and the loading degree of the third positive electrode coating 124c are the same as A2, and the loading degree of the second positive electrode coating 124b and the loading degree of the fourth positive electrode coating 124d are the same as B2 and less than A2. That is, the loading degree of the positive electrode coating 124 formed on the inner surface 122ay of the positive current collector 122a may be constant, and the loading degree of the positive electrode coating 124 formed on the outer surface 122ax of the positive current collector 122a may be constant.

[0074] For example, the loading degrees of the negative electrode coating 123 and the positive electrode coating 124 according to the comparative example may be as shown in Table 1.

[0075] [Table 1]

[0076]

[0077] In addition, when the loading degree of the positive electrode coating 124 and the negative electrode coating 123 is as shown in Table 1, according to the winding number of the electrode assembly 120, the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a can be Figure 3 The same as in. Figure 3 As shown in, in the electrode assembly 120 manufactured to have the same load degree as that in the comparative example, it is seen that from the winding front end Ra to the winding rear end Rb, the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a are both greater than the minimum negative electrode to positive electrode capacity ratio to prevent lithium precipitation.

[0078] However, in the electrode assembly 120 as in the comparative example, it is seen that the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a exceeds the minimum negative electrode to positive electrode capacity ratio and continues to increase until the winding turns of more than five turns to the winding rear end Rb. This means that as the winding turns of the electrode assembly 120 increase, the negative electrode coating 123 has an unnecessarily large capacity compared to the positive electrode coating 124, thereby reducing the output of the capacity of the electrode assembly 120. Of course, in the electrode assembly 120 as in the comparative example, the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a exceeds the minimum negative electrode to positive electrode capacity ratio for the winding turns of less than five turns starting from the winding front end Ra. However, in the electrode assembly 120 of the cylindrical battery, since the capacities of the positive electrode coating 124 and the negative electrode coating 123 gradually increase with the increase in the number of winding turns starting from the winding front end Ra, even if the negative electrode to positive electrode capacity ratio is large at the beginning of winding, it is regarded as a negligible and very small amount compared to the unnecessary excess capacity of the negative electrode coating 123 in the latter half of the winding.

[0079] Example 1

[0080] Similar to the comparative example, the load degree of the negative electrode coating 123 formed on the inner surface 121ay of the negative electrode collector 121a may be constant, and the load degree of the negative electrode coating 123 formed on the outer surface 121ax of the negative electrode collector 121a may be constant. Here, the first negative electrode coating 123a and the third negative electrode coating 123c may be formed integrally, and the second negative electrode coating 123b and the fourth negative electrode coating 123d may be formed integrally. Of course, in this case, the negative electrode tab 126 may form an uncoated portion on an area adjacent to the front end Ra or the rear end Rb of the negative electrode collector 121a, and may be attached to the uncoated portion.

[0081] The loading degree of the first positive electrode coating 124a is A2, and the loading degree of the second positive electrode coating 124b is B2 which is smaller than A2. The loading degrees of the third positive electrode coating 124c and the fourth positive electrode coating 124d may be the same as C2, and may be smaller than A2 and larger than B2. That is, the loading degree of the third positive electrode coating 124c formed on the same surface of the positive electrode collector 122a may be smaller than the loading degree of the first positive electrode coating 124a, and the loading degree of the fourth positive electrode coating 124d formed on the same surface of the positive electrode collector 122a may be larger than the loading degree of the second positive electrode coating 124b.

[0082] That is, the load degree of the positive electrode coating 124 on the front end region X can be similar to the load degree of the positive electrode coating 124 on the front end region X in the comparative example, and the load degree of the positive electrode coating 124 on the rear end region Y can be adjusted to increase the output of the capacity of the electrode assembly 120.

[0083] For example, the loading degrees of the negative electrode coating 123 and the positive electrode coating 124 of the electrode assembly 120 as in Example 1 may be as shown in Table 2. As shown in Table 2, the sum of the loading degree of the first positive electrode coating 124a and the loading degree of the second positive electrode coating 124b may be the same as the sum of the loading degree of the third positive electrode coating 124c and the loading degree of the fourth positive electrode coating 124d.

[0084] [Table 2]

[0085]

[0086] In addition, when the loading degree of the positive electrode coating 124 and the loading degree of the negative electrode coating 123 are as shown in Table 2, according to the winding number of the electrode assembly 120, the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a can be Figure 4 The same as in. Figure 4 As shown in, in the electrode assembly 120 manufactured to have the same load degree as that in an example of Example 1 (Table 2), the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a on the front end area X and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a on the front end area X are the same as those in the comparative example.

[0087] like Figure 4As shown in, in the electrode assembly 120 manufactured to have the same load degree as that in an example of Example 1 (Table 2), it is seen that the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a on the rear end region Y is reduced compared to the comparative example, and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a on the rear end region Y is increased compared to the comparative example.

[0088] That is, in an electrode assembly 120 manufactured to have the same load level as that in the example of Example 1 (Table 2), the load level of the positive electrode coating 124 on the rear end region Y can be adjusted so that the negative electrode to positive electrode capacity ratio is similar to the minimum negative electrode to positive electrode capacity ratio.

[0089] Therefore, in the electrode assembly 120 as in Example 1, the capacity of the negative electrode coating 123 can be prevented from being unnecessarily increased on the rear end region Y, and the output of the capacity of the electrode assembly 120 can be further improved compared to the comparative example.

[0090] In Table 2, although the third positive electrode coating layer 124c and the fourth positive electrode coating layer 124d have numerical differences in two decimal places, such a difference (less than 0.05) may be regarded as the same loading degree in the present invention.

[0091] In addition, as another example of Embodiment 1, the loading degrees of the negative electrode coating 123 and the positive electrode coating 124 of the electrode assembly 120 may be as shown in Table 3. As shown in Table 3, the sum of the loading degree of the first positive electrode coating 124a and the loading degree of the second positive electrode coating 124b may be less than the sum of the loading degree of the third positive electrode coating 124c and the loading degree of the fourth positive electrode coating 124d.

[0092] [Table 3]

[0093]

[0094] In addition, when the loading degree of the positive electrode coating 124 and the loading degree of the negative electrode coating 123 are as shown in Table 3, according to the winding number of the electrode assembly 120, the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a can be Figure 5 When comparing the example of Embodiment 1 (Table 2) with Table 3, Table 2 and Table 3 are the same except that the loading degree of the third positive electrode coating 124c and the loading degree of the fourth positive electrode coating 124d are changed so that the sum of the loading degrees is greater than the sum of the loading degree of the first positive electrode coating 124a and the loading degree of the second positive electrode coating 124b. Figure 5As shown in , when the sum of the loading degree of the third positive electrode coating 124c and the loading degree of the fourth positive electrode coating 124d is greater than the sum of the loading degree of the first positive electrode coating 124a and the loading degree of the second positive electrode coating 124b, it can be seen that, compared with the example of Example 1 (Table 2, Figure 4 ), the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive current collector 122a on the rear end region Y and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive current collector 122a on the rear end region Y are further reduced. That is, in the electrode assembly 120 as in another example (Table 3) of Embodiment 1, the load degree of the positive electrode coating 124 on the rear end region Y is set to be greater than the load degree of the positive electrode coating 124 on the front end region X, so that the negative electrode to positive electrode capacity ratio is similar to the minimum capacity ratio for preventing lithium precipitation. In the electrode assembly 120 according to another example (Table 3) of Embodiment 1 as described above, the capacity of the negative electrode coating 123 can be prevented from being unnecessarily increased, and the output of the capacity of the electrode assembly 120 can be further improved compared with the example (Table 2) of Embodiment 1.

[0095] Example 2

[0096] The loading degree of the first negative electrode coating 123a is A2, and the loading degree of the second negative electrode coating 123b is B2 which is smaller than A2. The loading degree of the third negative electrode coating 123c and the loading degree of the fourth negative electrode coating 123d may be the same as C2, but may be smaller than A2 and larger than B2. That is, the loading degree of the third negative electrode coating 123c may be smaller than the loading degree of the first negative electrode coating 123a formed on the same surface of the negative electrode collector 121a, and the loading degree of the fourth negative electrode coating 123d may be larger than the loading degree of the second negative electrode coating 123b formed on the same surface of the negative electrode collector 121a.

[0097] That is, the load degree of the negative electrode coating 123 on the front end region X can be similar to the load degree of the negative electrode coating 123 on the front end region X in the comparative example, and the load degree of the negative electrode coating 123 on the rear end region Y can be adjusted to increase the output of the capacity of the electrode assembly 120.

[0098] As in the comparative example, the load degree of the positive electrode coating 124 formed on the inner surface 122ay of the positive electrode collector 122a may be constant, and the load degree of the positive electrode coating 124 formed on the outer surface 122ax of the positive electrode collector 122a may be constant. Here, the first positive electrode coating 124a and the third positive electrode coating 124c may be formed integrally, and the second positive electrode coating 124b and the fourth positive electrode coating 124d may be formed integrally. Of course, in this case, the positive electrode tab 127 may form an uncoated portion on an area adjacent to the front end Ra or the rear end Rb of the positive electrode collector 122a, and may be attached to the uncoated portion.

[0099] For example, the loading degrees of the negative electrode coating 123 and the positive electrode coating 124 of the electrode assembly 120 as in Example 2 may be as shown in Table 4. As shown in Table 4, the sum of the loading degree of the first negative electrode coating 123a and the loading degree of the second negative electrode coating 123b may be the same as the sum of the loading degree of the third negative electrode coating 123c and the loading degree of the fourth negative electrode coating 123d.

[0100] [Table 4]

[0101]

[0102] In addition, when the loading degree of the positive electrode coating 124 and the loading degree of the negative electrode coating 123 are as shown in Table 4, according to the winding number of the electrode assembly 120, the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a can be Figure 6 The same as in. Figure 6 As shown in, in the electrode assembly 120 manufactured to have the same load degree as that in an example of Example 2 (Table 4), the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a on the front end area X and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a on the front end area X are the same as those in the comparative example.

[0103] like Figure 6As shown in, in the electrode assembly 120 manufactured to have the same load degree as that in one example of Embodiment 2 (Table 4), it is seen that the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a on the rear end region Y is reduced compared to the comparative example, and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a on the rear end region Y is increased compared to the comparative example. That is, in the electrode assembly 120 manufactured to have the same load degree as that in the example of Embodiment 2 (Table 4), the load degree of the negative electrode coating 123 on the rear end region Y can be adjusted so that the negative electrode to positive electrode capacity ratio is similar to the minimum negative electrode to positive electrode capacity ratio.

[0104] That is, in the electrode assembly 120 as in Example 2, the load degree of the negative electrode coating 123 on the rear end region Y can be adjusted to prevent the capacity of the negative electrode coating 123 from increasing unnecessarily, and thus, the output of the capacity of the electrode assembly 120 can be further improved compared with the comparative example.

[0105] In addition, as another example of Embodiment 2, the loading degrees of the negative electrode coating 123 and the positive electrode coating 124 of the electrode assembly 120 may be as shown in Table 5. As shown in Table 5, the sum of the loading degree of the first negative electrode coating 123a and the loading degree of the second negative electrode coating 123b may be greater than the sum of the loading degree of the third negative electrode coating 123c and the loading degree of the fourth negative electrode coating 123d.

[0106] [Table 5]

[0107]

[0108] In addition, when the loading degree of the positive electrode coating 124 and the negative electrode coating 123 is as shown in Table 5, according to the winding number of the electrode assembly 120, the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a can be Figure 7 When comparing the example of Embodiment 2 (Table 4) with Table 5, Table 4 and Table 5 are the same except that the loading degree of the third negative electrode coating 123c and the loading degree of the fourth negative electrode coating 123d are changed so that the sum of the loading degrees is less than the sum of the loading degree of the first negative electrode coating 123a and the loading degree of the second negative electrode coating 123b. Figure 7 As shown in , when the sum of the loading degree of the third negative electrode coating 123c and the loading degree of the fourth negative electrode coating 123d is less than the sum of the loading degree of the first negative electrode coating 123a and the loading degree of the second negative electrode coating 123b, it can be seen that, compared with the example of Example 2 (Table 2, Figure 4), the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the negative electrode collector 122a on the rear end region Y and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the negative electrode collector 122a on the rear end region Y are further reduced. That is, in the electrode assembly 120 as in another example (Table 5) of Example 2, the load degree of the negative electrode coating 123 on the rear end region Y is set to be less than the load degree of the negative electrode coating 123 on the front end region X, so that the negative electrode to positive electrode capacity ratio is similar to the minimum capacity ratio for preventing lithium precipitation. In the electrode assembly 120 according to another example (Table 5) of Example 2 as described above, the capacity of the negative electrode coating 123 can be prevented from being unnecessarily increased, and the output of the capacity of the electrode assembly 120 can be further improved compared with the example (Table 4) of Example 2.

[0109] Example 3

[0110] The loading degree of the first negative electrode coating 123a is A1, and the loading degree of the second negative electrode coating 123b is B1 which is smaller than A1. The loading degree of the third negative electrode coating 123c is C1, and the loading degree of the fourth negative electrode coating 123d is D1 which is smaller than C1. In addition, the loading degree B1 of the second negative electrode coating 123b may be smaller than the loading degree D1 of the fourth negative electrode coating 123d, and the loading degree A1 of the first negative electrode coating 123a may be greater than the loading degree C1 of the third negative electrode coating 123c.

[0111] That is, the load degree of the negative electrode coating 123 on the front end region X can be similar to the load degree of the negative electrode coating 123 on the front end region X in the comparative example, and the load degree of the negative electrode coating 123 on the rear end region Y can be adjusted to increase the output of the capacity of the electrode assembly 120.

[0112] The loading degree of the first positive electrode coating 124a is A2, and the loading degree of the second positive electrode coating 124b is B2 which is smaller than A2. The loading degree of the third positive electrode coating 124c is C2, and the loading degree of the fourth positive electrode coating 124d is D2 which is smaller than C2. In addition, the loading degree B2 of the second positive electrode coating 124b may be smaller than the loading degree D2 of the fourth positive electrode coating 124d, and the loading degree A2 of the first positive electrode coating 124a may be greater than or equal to the loading degree C2 of the third positive electrode coating 124c.

[0113] That is, the load degree of the positive electrode coating 124 on the front end region X can be similar to the load degree of the positive electrode coating 124 on the front end region X in the comparative example, and the load degree of the positive electrode coating 124 on the rear end region Y can be adjusted to increase the output of the capacity of the electrode assembly 120.

[0114] For example, the load levels of the negative electrode coating 123 and the positive electrode coating 124 of the electrode assembly 120 as in Example 3 may be as shown in Table 6. As shown in Table 6, the sum of the load level of the first negative electrode coating 123a and the load level of the second negative electrode coating 123b may be the same as the sum of the load level of the third negative electrode coating 123c and the load level of the fourth negative electrode coating 123d. In addition, the sum of the load level of the first positive electrode coating 124a and the load level of the second positive electrode coating 124b may be the same as the sum of the load level of the third positive electrode coating 124c and the load level of the fourth positive electrode coating 124d. In addition, the load level of the first positive electrode coating 124a may be greater than the load level of the third positive electrode coating 124c.

[0115] [Table 6]

[0116]

[0117] In addition, when the loading degree of the positive electrode coating 124 and the loading degree of the negative electrode coating 123 are as shown in Table 6, according to the winding number of the electrode assembly 120, the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a can be Figure 8 The same as in. Figure 8 As shown in, in the electrode assembly 120 manufactured to have the same load degree as that in an example of Example 3 (Table 6), the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a on the front end area X and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a on the front end area X are the same as those in the comparative example.

[0118] like Figure 8 As shown in, in the electrode assembly 120 manufactured to have the same load degree as that in one example of Embodiment 3 (Table 6), it is seen that the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a on the rear end region Y is reduced compared to the comparative example, and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a on the rear end region Y is increased compared to the comparative example. That is, in the electrode assembly 120 manufactured to have the same load degree as that in the example of Embodiment 3 (Table 6), the load degree of the negative electrode coating 123 and the load degree of the positive electrode coating 124 on the rear end region Y can be adjusted so that the negative electrode to positive electrode capacity ratio is similar to the minimum negative electrode to positive electrode capacity ratio.

[0119] That is, in the electrode assembly 120 as in Example 3, the load degree of the negative electrode coating 123 and the load degree of the positive electrode coating 124 on the rear end region Y can be adjusted to prevent the capacity of the negative electrode coating 123 from increasing unnecessarily, and thus, the output of the capacity of the electrode assembly 120 can be further improved compared with the comparative example.

[0120] In addition, as another example of Embodiment 3, the load levels of the negative electrode coating 123 and the positive electrode coating 124 of the electrode assembly 120 may be as shown in Table 7. As shown in Table 7, the sum of the load level of the first negative electrode coating 123a and the load level of the second negative electrode coating 123b may be the same as the sum of the load level of the third negative electrode coating 123c and the load level of the fourth negative electrode coating 123d. In addition, the sum of the load level of the first positive electrode coating 124a and the load level of the second positive electrode coating 124b may be less than the sum of the load level of the third positive electrode coating 124c and the load level of the fourth positive electrode coating 124d.

[0121] [Table 7]

[0122]

[0123] In addition, when the loading degree of the positive electrode coating 124 and the negative electrode coating 123 is as shown in Table 7, according to the winding number of the electrode assembly 120, the negative electrode to positive electrode capacity ratio of the inner surface 122ay of the positive electrode collector 122a and the negative electrode to positive electrode capacity ratio of the outer surface 122ax of the positive electrode collector 122a can be Fig. 9 When comparing the example of Embodiment 3 (Table 6) with Table 7, Table 6 and Table 7 are the same except that the loading degree of the third positive electrode coating 124c and the loading degree of the fourth positive electrode coating 124d are changed so that the sum of the loading degrees is greater than the sum of the loading degree of the first positive electrode coating 124a and the loading degree of the second positive electrode coating 124b. Here, the loading degree of the first positive electrode coating 124a may be equal to or greater than the loading degree of the third positive electrode coating 124c. Fig. 9 As shown in , when the sum of the loading degree of the third positive electrode coating 124c and the loading degree of the fourth positive electrode coating 124d is greater than the sum of the loading degree of the first positive electrode coating 124a and the loading degree of the second positive electrode coating 124b, it can be seen that, compared with the example of Example 3 (Table 6, Figure 8), the capacity ratio of the negative electrode to the positive electrode on the inner surface 122ay of the positive current collector 122a on the rear end region Y and the capacity ratio of the negative electrode to the positive electrode on the outer surface 122ax of the positive current collector 122a on the rear end region Y are further reduced. That is, in the electrode assembly 120 in another embodiment (Table 7) as in Example 3, the load degree of the positive electrode coating 124 on the rear end region Y is set to be greater than the load degree of the positive electrode coating 124 on the front end region X, so that the negative electrode to positive electrode capacity ratio is similar to the minimum capacity ratio for preventing lithium precipitation. In the electrode assembly 120 according to another example (Table 7) of Example 3 as described above, the capacity of the negative electrode coating 123 can be prevented from being unnecessarily increased, and the output of the capacity of the electrode assembly 120 can be further improved compared with the example (Table 6) of Example 3.

[0124] The above-mentioned embodiments are merely embodiments of electrode assemblies and secondary batteries including the same, and therefore, the present invention is not limited to the aforementioned embodiments, and a person of ordinary skill in the art will also understand that various changes in form and details may be made without departing from the spirit and scope of the present invention as defined by the appended claims.

[0125] Industrial Applicability

[0126] The present invention can be applied to the field of secondary batteries used in various electronic devices and electric vehicles.

Claims

1. An electrode assembly, comprising: a negative electrode plate on which a negative electrode coating is formed on both surfaces of a negative electrode current collector; a positive electrode plate on which a positive electrode coating is formed on both surfaces of a positive electrode current collector; as well as A separator is placed between the positive electrode plate and the negative electrode plate, Wherein, the positive electrode coating comprises: a first positive electrode coating layer formed on a front end region of a first surface of the positive electrode current collector; a second positive electrode coating layer formed on the front end region of a second surface of the positive electrode current collector which is an opposite surface to the first surface; a third positive electrode coating layer formed on a rear end region of the first surface of the positive electrode current collector; and a fourth positive electrode coating layer formed on the rear end region of the second surface of the positive electrode current collector, wherein the loading degree of the first positive electrode coating is greater than the loading degree of the second positive electrode coating, and each of a loading degree of the third positive electrode coating layer and a loading degree of the fourth positive electrode coating layer is smaller than the loading degree of the first positive electrode coating layer and larger than the loading degree of the second positive electrode coating layer, Wherein, the degree of loading refers to the amount or weight of the coating applied per unit area, and Wherein, the positive plate further comprises: a first positive electrode non-coating portion, on the first surface, the first positive electrode coating layer and the third positive electrode coating layer are spaced apart from each other so that the positive electrode coating layer is not formed on the first positive electrode non-coating portion; and A second positive electrode non-coating portion, on the second surface, the second positive electrode coating layer and the fourth positive electrode coating layer are spaced apart from each other so that the positive electrode coating layer is not formed on the second positive electrode non-coating portion.

2. The electrode assembly according to claim 1, wherein: A sum of the loading degree of the first positive electrode coating and the loading degree of the second positive electrode coating is equal to or less than a sum of the loading degree of the third positive electrode coating and the loading degree of the fourth positive electrode coating.

3. The electrode assembly according to claim 1, wherein: The negative electrode coating comprises: a first negative electrode coating layer formed on a front end region of a first surface of the negative electrode current collector; a second negative electrode coating layer formed on the front end region of a second surface of the negative electrode current collector which is an opposite surface to the first surface; a third negative electrode coating layer formed on a rear end region of the first surface of the negative electrode current collector; and A fourth negative electrode coating layer is formed on the rear end region of the second surface of the negative electrode current collector.

4. The electrode assembly according to claim 3, wherein: The loading degree of the first negative electrode coating is the same as the loading degree of the third negative electrode coating, and The loading degree of the second negative electrode coating is the same as the loading degree of the fourth negative electrode coating and is smaller than the loading degree of the first negative electrode coating.

5. The electrode assembly according to claim 3, wherein: The loading degree of the first negative electrode coating is greater than the loading degree of the second negative electrode coating, and The loading degree of the third negative electrode coating and the loading degree of the fourth negative electrode coating are smaller than the loading degree of the first negative electrode coating and larger than the loading degree of the second negative electrode coating.

6. The electrode assembly according to claim 5, wherein: The sum of the loading degree of the first negative electrode coating and the loading degree of the second negative electrode coating is the same as the sum of the loading degree of the third negative electrode coating and the loading degree of the fourth negative electrode coating.

7. The electrode assembly according to claim 1, wherein: The positive plate also includes: A positive electrode tab is attached to any one of the first positive electrode non-coating portion and the second positive electrode non-coating portion.

8. The electrode assembly according to claim 3, wherein: The negative plate also includes: a first negative electrode uncoated portion, wherein the first negative electrode coating and the third negative electrode coating are spaced apart from each other on the first surface of the negative electrode current collector so that the negative electrode coating is not formed on the first negative electrode uncoated portion; a second negative electrode non-coating portion, on the second surface of the negative electrode current collector, the second negative electrode coating and the fourth negative electrode coating are spaced apart from each other so that the negative electrode coating is not formed on the second negative electrode non-coating portion; and A negative electrode tab is attached to any one of the first negative electrode non-coating portion and the second negative electrode non-coating portion.

9. An electrode assembly, comprising: a negative electrode plate on which a negative electrode coating is formed on both surfaces of a negative electrode current collector; a positive electrode plate on which a positive electrode coating is formed on both surfaces of a positive electrode current collector; as well as A separator is placed between the positive electrode plate and the negative electrode plate, Wherein, the negative electrode coating comprises: a first negative electrode coating layer formed on a front end region of a first surface of the negative electrode current collector; a second negative electrode coating layer formed on the front end region of a second surface of the negative electrode current collector which is an opposite surface to the first surface; a third negative electrode coating layer formed on a rear end region of the first surface of the negative electrode current collector; and a fourth negative electrode coating formed on the rear end region of the second surface of the negative electrode current collector, wherein the loading degree of the first negative electrode coating is greater than the loading degree of the second negative electrode coating, and each of a loading degree of the third negative electrode coating and a loading degree of the fourth negative electrode coating is smaller than the loading degree of the first negative electrode coating and larger than the loading degree of the second negative electrode coating, Wherein, the degree of loading refers to the amount or weight of the coating applied per unit area, and Wherein, the negative electrode plate further comprises: a first negative electrode non-coating portion, on the first surface, the first negative electrode coating and the third negative electrode coating are spaced apart from each other so that the negative electrode coating is not formed on the first negative electrode non-coating portion; and A second negative electrode non-coating portion, on the second surface, the second negative electrode coating layer and the fourth negative electrode coating layer are spaced apart from each other so that the negative electrode coating layer is not formed on the second negative electrode non-coating portion.

10. The electrode assembly according to claim 9, wherein: A sum of the loading degree of the first negative electrode coating and the loading degree of the second negative electrode coating is equal to or greater than a sum of the loading degree of the third negative electrode coating and the loading degree of the fourth negative electrode coating.

11. The electrode assembly according to claim 9, wherein: The positive electrode coating comprises: a first positive electrode coating layer formed on a front end region of a first surface of the positive electrode current collector; a second positive electrode coating layer formed on the front end region of a second surface of the positive electrode current collector which is an opposite surface to the first surface; a third positive electrode coating layer formed on a rear end region of the first surface of the positive electrode current collector; and a fourth positive electrode coating layer formed on the rear end region of the second surface of the positive electrode current collector, wherein the loading degree of the first positive electrode coating is the same as the loading degree of the third positive electrode coating, and The loading degree of the second positive electrode coating layer is the same as the loading degree of the fourth positive electrode coating layer and is smaller than the loading degree of the first positive electrode coating layer.

12. A secondary battery, comprising: The electrode assembly according to claim 1 or 9; a housing having an internal space, wherein the electrode assembly accommodates an electrolyte in the internal space; as well as A cover plate is coupled to an upper portion of the housing to seal the housing.

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