Method for passivating outermost negative electrode, method for manufacturing electrode assembly, and electrode assembly

Abstract

The present invention provides a method for passivating a pair of outermost negative electrodes, which are respectively disposed at the top and bottom of an electrode assembly including a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators, comprising a passivation step of forming a passivation region having a predetermined width (w) along an edge of one surface of the outermost negative electrode, wherein the width (w) in the passivation step is determined based on the horizontal length of the outermost negative electrode, the vertical length of the outermost negative electrode, and the number of monocells, each of which is composed of a separator, a negative electrode, a separator, and a positive electrode, in the electrode assembly. This provides a clear guide for the passivation process of the outermost negative electrode of the electrode assembly.

Description

[Technical Field]

[0001] The present invention relates to a method for passivating an outermost negative electrode, a method for manufacturing an electrode assembly, and an electrode assembly manufactured by the method. [Background technology]

[0002] With technological development and increasing demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing. Among such secondary batteries, lithium secondary batteries, which exhibit high energy density and working potential, long cycle life, and low self-discharge rate, have been commercialized and are widely used.

[0003] Furthermore, with growing concern about environmental issues, much research is being conducted into electric vehicles and hybrid electric vehicles that can replace vehicles that use fossil fuels such as gasoline and diesel, which are one of the main causes of air pollution. Nickel-metal hydride secondary batteries are mainly used as the power source for such electric vehicles and hybrid electric vehicles, but research into the use of lithium secondary batteries, which have high energy density and discharge voltage, is being actively conducted, and some of them have been commercialized.

[0004] Secondary batteries can also be classified according to the structure of their electrode assembly, which has a positive electrode / separator / negative electrode structure. Typical examples include jelly roll (wound) electrode assemblies, in which long sheet-shaped positive and negative electrodes are wound up with a separator between them; stacked (layered) electrode assemblies, in which multiple positive and negative electrodes cut to a specified size are stacked in order with a separator between them; and stack / folded electrode assemblies, which combine the wound and stacked types.

[0005] Such secondary batteries are generally manufactured by incorporating an electrode assembly, which includes a positive electrode plate and a negative electrode plate coated with positive and negative electrode active materials and a separator interposed therebetween, into a pouch-shaped case made of an aluminum laminate sheet.

[0006] The secondary battery thus manufactured undergoes an activation process for charging and discharging.

[0007] During the activation process, lithium ions move between the remaining electrodes (except for a pair of outermost negative electrodes located at the top and bottom of the electrode assembly), the separator, and the electrolyte, causing a charge-discharge reaction (hereinafter referred to as the main reaction).

[0008] On the other hand, at the outermost negative electrode, a local reaction occurs which does not participate in the main reaction but is involved in the charging and discharging of the adjacent electrode.

[0009] For example, the outermost negative electrode is charged as lithium inflows through diffusion through the electrolyte, and at this time, a potential difference occurs between the edge and the center of the outermost negative electrode, causing a side reaction.

[0010] When the ratio of local reactions to the main reactions exceeds a certain level, unnecessary electrolyte consumption and unevenness of the electrode assembly as a whole occur.

[0011] Conventionally, in order to prevent the outermost negative electrode from participating in a local reaction, a passivation process has been performed in which the surface or edge of the outermost negative electrode is coated with an insulating material.

[0012] The passivation process equalizes the potential difference between the edge and middle portion of the outermost negative electrode, thereby reducing side reactions caused by the potential difference.

[0013] It is advantageous in terms of efficiency to selectively perform the passivation process only when the ratio of local reactions to the main reaction is above a certain level. However, there is currently no clear guide to determine whether or not to perform the passivation process on the outermost negative electrode. Summary of the Invention [Problem to be solved by the invention]

[0014] An object of the present invention is to provide a method for passivating an outermost negative electrode, a method for manufacturing an electrode assembly, and an electrode assembly manufactured by the method, which can provide a clear guide for the passivation work of the outermost negative electrode of an electrode assembly. [Means for solving the problem]

[0015] To achieve this, one embodiment of the present invention provides a method for passivating a pair of outermost negative electrodes disposed at the top and bottom of an electrode assembly including a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators, the method comprising a passivation step of forming a passivation region having a predetermined width (w) along an edge of one surface of the outermost negative electrode, wherein the width (w) in the passivation step is determined based on the horizontal length of the outermost negative electrode, the vertical length of the outermost negative electrode, and the number of monocells each including a separator, a negative electrode, a separator, and a positive electrode in the electrode assembly.

[0016] In the method for passivating the outermost negative electrode, the width (w) in the passivation step is determined within a range of 0.9P1 to 1.2P1, and P1 can be calculated by the following Equation 1:

number

[0017] In Equation 1, a1 is the horizontal length of the outermost negative electrode, b1 is the vertical length of the outermost negative electrode, and c1 is the number of monocells each consisting of a separator, a negative electrode, a separator, and a positive electrode in the electrode assembly.

[0018] In addition, in the method for passivating the outermost negative electrode, the width (w) in the passivation step may be determined based on the ratio (A / B) of the total surface area (A) of one surface of the plurality of negative electrodes in the electrode assembly to the total surface area (B) of one surface of the plurality of positive electrodes.

[0019] In addition, in the method for passivating the outermost negative electrode, the width (w) in the passivation step is determined within a range of 1.0X1 to 1.25X1 when the ratio (A / B) is 1.1 or more and less than 1.2, and X1 can be calculated by the following Equation 2:

number

[0020] In the above formula 2, Y1 is the horizontal length of the outermost negative electrode, and Z1 is the vertical length of the outermost negative electrode.

[0021] In addition, in the method for passivating the outermost negative electrode, the width (w) in the passivation step is determined within a range of 1.0X2 to 1.5X2 when the ratio (A / B) is 1.2 or more, and X2 can be calculated by the following Equation 3:

number

[0022] In the above formula 3, Y2 is the horizontal length of the outermost negative electrode, and Z2 is the vertical length of the outermost negative electrode.

[0023] In the method for passivating the outermost negative electrode, the passivation area may be formed by attaching an insulating tape or coating an insulating material.

[0024] In the method for passivating the outermost negative electrode, the insulating tape may have a polyimide layer formed on one or both sides.

[0025] In the method for passivating an outermost negative electrode, the insulating material may include an epoxy compound or aluminum oxide.

[0026] According to another embodiment of the present invention, there is provided a method for manufacturing an electrode assembly, the method comprising: a passivation step of forming a passivation region having a predetermined width (w) along an edge of one surface of a first negative electrode; a step of manufacturing a first mono-cell by sequentially stacking a separator, a first negative electrode having the passivation region formed thereon, a separator, and a positive electrode; a step of manufacturing a plurality of second mono-cells by sequentially stacking a second negative electrode having no separator, a separator, and a positive electrode; a step of manufacturing a half-cell by sequentially stacking a separator, a first negative electrode having the passivation region formed thereon, and a separator; a step of manufacturing a stack by stacking a plurality of second mono-cells on the first mono-cell; and a step of manufacturing an electrode assembly by stacking the half-cell on the second mono-cell disposed at the top of the stack, wherein the width (w) in the passivation step is determined based on the horizontal length of the first negative electrode, the vertical length of the first negative electrode, and the number of first and second mono-cells in the electrode assembly.

[0027] In addition, in the method for manufacturing the electrode assembly, the width (w) in the passivation step is determined within a range of 0.9P2 to 1.2P2, and P2 can be calculated by the following Equation 4:

number

[0028] In the above formula 4, a2 is the horizontal length of the first negative electrode, b2 is the vertical length of the first negative electrode, and c2 is the number of first and second mono-cells.

[0029] In addition, in the method for manufacturing the electrode assembly, the width (w) in the passivation step may be determined based on the ratio (A / B) of the total area of ​​one surface of the plurality of negative electrodes (A) to the total area of ​​one surface of the plurality of positive electrodes (B) in the electrode assembly.

[0030] In addition, in the method for manufacturing the electrode assembly, the width (w) in the inactivation step is determined within a range of 1.0X3 to 1.25X3 when the ratio (A / B) is 1.1 or more and less than 1.2, and X3 can be calculated by the following Equation 5:

number

[0031] In the above formula 5, Y2 is the horizontal length of the first negative electrode, and Z2 is the vertical length of the first negative electrode.

[0032] In addition, in the method for manufacturing the electrode assembly, the width (w) in the passivation step is determined within a range of 1.0X4 to 1.5X4 when the ratio (A / B) is 1.2 or more, and X4 can be calculated by the following Equation 6:

number

[0033] In the above formula 6, Y2 is the horizontal length of the first negative electrode, and Z2 is the vertical length of the first negative electrode.

[0034] The method for manufacturing the electrode assembly may further include a determination step of determining whether or not passivation of the first mono-cell and the first negative electrode in the half-cell is necessary based on the number of first and second mono-cells before the passivation step.

[0035] In addition, in the method for manufacturing the electrode assembly, the determining step may determine that passivation of the first mono-cell and the first negative electrode in the half-cell is necessary when the number of first and second mono-cells is less than a predetermined value.

[0036] In addition, in the method for manufacturing the electrode assembly, the determining step may determine that passivation of the first mono-cell and the first negative electrode in the half-cell is necessary when the number of first and second mono-cells is less than 15.

[0037] The method for manufacturing the electrode assembly may further include a determination step, prior to the passivation step, of determining whether passivation of the first negative electrode in the first mono-cell and the half-cell is necessary based on the ratio (A / B).

[0038] In addition, in the method for manufacturing the electrode assembly, the determining step may determine that passivation of the first negative electrode in the first mono-cell and the half-cell is necessary if the ratio (A / B) is 1.1 or more.

[0039] According to another embodiment of the present invention, there is provided an electrode assembly including: a first mono-cell in which a separator, a first negative electrode having a passivation region formed along one edge thereof with a predetermined width (w), a separator, and a positive electrode are stacked in this order; a plurality of second mono-cells stacked on the first mono-cell in which a separator, a second negative electrode, a separator, and a positive electrode are stacked in this order; and a half-cell in which a separator, a first negative electrode having a passivation region formed thereon, and a separator are stacked in this order on an uppermost second mono-cell, wherein the width (w) of the passivation region is in the range of 0.9P2 to 1.2P2, and P2 is calculated by the following Equation 4:

number

[0040] In the above formula 4, a2 is the horizontal length of the first negative electrode, b2 is the vertical length of the first negative electrode, and c2 is the number of first and second mono-cells.

[0041] According to another embodiment of the present invention, there is provided an electrode assembly including a first mono-cell in which a separator, a first negative electrode having a passivation region formed along an edge of one side with a predetermined width (w), a separator, and a positive electrode are stacked in this order; a plurality of second mono-cells stacked on the first mono-cell in which a separator, a second negative electrode, a separator, and a positive electrode are stacked in this order; and a half-cell in which a separator, a first negative electrode having a passivation region formed along an edge of the second mono-cell and a separator are stacked in this order on the second mono-cell disposed in the uppermost layer, the half-cell having a separator, a first negative electrode having a passivation region formed along an edge of the first mono-cell in which the total area of ​​one side of the plurality of negative electrodes in the electrode assembly is (A). When the ratio (A / B) of the sum of the areas of one surface of the plurality of negative electrodes (A) to the sum of the areas of one surface of the plurality of positive electrodes (B) is 1.1 or more and less than 1.2, the width (w) of the passivation region is in the range of 1.0X3 to 1.25X3; when the ratio (A / B) of the sum of the areas of one surface of the plurality of negative electrodes (A) to the sum of the areas of one surface of the plurality of positive electrodes (B) in the electrode assembly is 1.2 or more, the width (w) of the passivation region is in the range of 1.0X4 to 1.5X4, where X3 and X4 are calculated by the following Equations 5 and 6, respectively.

number

number

[0042] In the above formulas 5 and 6, Y2 is the horizontal length of the first negative electrode, and Z2 is the vertical length of the first negative electrode. [Effects of the Invention]

[0043] The present invention can provide a clear guide for the passivation operation of the outermost negative electrode of the electrode assembly. [Brief explanation of the drawings]

[0044] [Figure 1] 1 is a diagram showing a stack structure of an electrode assembly according to an embodiment of the present invention; [Figure 2] FIG. 10 is a diagram showing the inactive region of the outermost negative electrode. [Figure 3] FIG. 1 shows a mono-cell and a half-cell including a double-sided electrode with two cross-sectional electrodes joined together. [Figure 4] 1 is a diagram illustrating a local reaction and a main reaction in an electrode assembly during an activation process. DETAILED DESCRIPTION OF THE INVENTION

[0045] Hereinafter, a method for passivating an outermost negative electrode according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0046] FIG. 1 is a diagram showing the stacked structure of an electrode assembly according to one embodiment of the present invention, FIG. 2 is a diagram showing the passivation region of the outermost negative electrode, and FIG. 3 is a diagram showing a mono-cell and a half-cell including a double-sided electrode in which two cross-sectional electrodes are joined.

[0047] The present invention relates to a method for inactivating a pair of outermost negative electrodes (102-1) disposed at the top and bottom of an electrode assembly (100) including a plurality of positive electrodes (103), a plurality of negative electrodes (102), and a plurality of separators (101).

[0048] The method includes a passivation step of forming a passivation region (104) having a predetermined width (w) along the edge of one surface of the outermost negative electrode (102-1).

[0049] The width (w) in the inactivation step is determined based on the horizontal length of the outermost negative electrode (102-1), the vertical length of the outermost negative electrode (102-1), and the number of monocells (110) in the electrode assembly (100) each consisting of a separator (101), a negative electrode (102), a separator (101), and a positive electrode (103).

[0050] First, in the present invention, the electrode assembly (100) may include a monocell (110) in which a separator (101), an anode (102), a separator (101), and a cathode (103) are stacked in this order, and a half-cell (130) in which a separator (101), an anode (102), and a separator (101) are stacked in this order.

[0051] The electrode assembly (100) may include a stack (120) in which a plurality of mono-cells (110) are stacked, and a half-cell (130) stacked on the stack (120).

[0052] The electrode assembly (100) can have a first mono-cell (110-1) arranged at the bottom and a half-cell (130) arranged at the top.

[0053] In the present invention, in order to distinguish between the mono-cell placed at the bottom and the other mono-cells, the mono-cell placed at the bottom will be referred to as the first mono-cell (110-1), and the other mono-cells will be referred to as the second mono-cell (110-2).

[0054] The first mono-cell 110-1 and the second mono-cell 110-2 are distinguished by whether or not a passivation region is formed on the negative electrode. The first mono-cell 110-1 includes a first negative electrode 102-1 with a passivation region formed thereon, and the second mono-cell 110-2 includes a second negative electrode 102-2 without a passivation region formed thereon.

[0055] In the present invention, the first negative electrode 102-1 having the inactivated region 104 formed thereon is the outermost negative electrode. Therefore, the first negative electrode will be designated by the same reference numeral "102-1" as the outermost negative electrode. To distinguish the outermost negative electrode from the remaining negative electrodes, the remaining negative electrodes will be referred to as the second negative electrode 102-2.

[0056] In the present invention, the outermost negative electrode (102-1) may refer to the negative electrode of the first mono-cell (110-1) and the negative electrode of the half-cell (130) located at the bottom of the stack (120).

[0057] Since the mono-cell (110) and half-cell (130) are manufactured by laminating a separator on both sides of the negative electrode (102), the passivation step can be performed before laminating the negative electrode (102) and the separator (101).

[0058] That is, in the present invention, the deactivation step can be performed before the mono-cell (110) and the half-cell (130) are fabricated.

[0059] For example, the first mono-cell (110-1) located at the bottom and the half-cell (130) located at the top can be manufactured by stacking the outermost negative electrode (102-1) and separator (101) on which an inactivation region has been formed through the inactivation step according to the method of the present invention.

[0060] In the present invention, the positive electrode (103) or the negative electrode (102) has one surface of a rectangle consisting of a pair of long sides and a pair of short sides. In the present invention, the horizontal length of the outermost negative electrode means the length of the long sides, and the vertical length of the outermost negative electrode means the length of the short sides.

[0061] In addition, in the present invention, one surface of the electrode has a rectangular shape, and in the present invention, one surface of the electrode is interpreted as excluding an electrode tab formed protruding outside the cross section of the rectangle.

[0062] The width (w) is determined based on the horizontal length of the outermost negative electrode (102-1), the vertical length of the outermost negative electrode (102-1), and the number of mono-cells (110) in the electrode assembly (100) each including a separator (101), a negative electrode (102), a separator (101), and a positive electrode (103). This ensures a minimum inactive region that does not degrade battery performance, and is expected to reduce manufacturing costs consumed to form the inactive region.

[0063] In one example, the width (w) in the inactivation step is determined within the range of 0.9P1 to 1.2P1, where P1 can be calculated using the following Equation 1:

number

[0064] In Equation 1, a1 is the horizontal length of the outermost negative electrode (102-1), b1 is the vertical length of the outermost negative electrode (102-1), and c1 is the number of mono-cells (110) in the electrode assembly (100), each of which is composed of a separator (101), a negative electrode (102), a separator (101), and a positive electrode (103).

[0065] In the above formula 1, c1 may be a natural number less than 15, for example, a natural number from 2 to 14.

[0066] The number of mono-cells (110) can be predetermined before manufacturing the electrode assembly (100), and therefore the width of the passivation region can be adjusted taking into account the c1 value in the passivation step performed before manufacturing the mono-cells (110) and half-cells (130).

[0067] For example, when manufacturing an electrode assembly (100) having 14 monocells (110), the width of the passivation region can be adjusted using the value of p calculated by substituting 14 for c in Equation 1.

[0068] The width of the inactivated region (104) may be measured in mm or cm.

[0069] The electrode assembly (100) may include multiple mono-cells (110) and one half-cell (130), and thus the number of negative electrodes (102) and positive electrodes (103) may differ from each other, for example, there may be one more negative electrode (102) than positive electrode (103).

[0070] An electrode assembly (100) containing two mono-cells (110) and one half-cell (130) can contain two positive electrodes (103) and three negative electrodes (102).

[0071] In one example, the passivation region 104 can be formed on one side of the negative electrode that contacts the outermost separator.

[0072] Specifically, the first mono-cell (110-1) located at the bottom has a first separator (101-1), an outermost negative electrode (102-1), a second separator (101-2), and a positive electrode (103) stacked in this order, and the inactivated region (104) may be formed on one surface (102-1a) of the outermost negative electrode (102-1) facing the first separator (101-1).

[0073] In addition, the uppermost half cell (130) has a third separator (101-3), an outermost negative electrode (102-1), and a fourth separator (101-4) stacked in this order, and the inactivated region (104) may be formed on one surface (102-1a) of the outermost negative electrode (102-1) facing the fourth separator (101-4).

[0074] FIG. 3 shows a mono-cell and a half-cell including a double-sided electrode with two cross-sectional electrodes joined together.

[0075] Referring to FIG. 3, the positive electrode may be a double-sided positive electrode formed by joining two cross-sectional positive electrodes, and the negative electrode may be a double-sided negative electrode formed by joining two cross-sectional negative electrodes.

[0076] For example, an electrode assembly (100) including two mono-cells (110) and one half-cell (130) can include two double-sided positive electrodes and three double-sided negative electrodes, resulting in four cross-sectional positive electrodes and six cross-sectional negative electrodes.

[0077] Meanwhile, in the case of a double-sided negative electrode in which two cross-sectional negative electrodes are joined together, the inactivated region 104 may be formed on one side of the cross-sectional negative electrode located at the outermost side.

[0078] For example, as shown in FIG. 3(a), the uppermost half cell (130) may have a third separator (101-3), a third cross-sectional anode (102a), a fourth cross-sectional anode (102b), and a fourth separator (101-4) stacked in that order, and an inactivated region (104) may be formed on one side of the second cross-sectional anode (102b) facing the fourth separator (101-4).

[0079] Also, as shown in FIG. 3(b), the first monocell (110-1) located at the bottom has a first separator (101-1), a first cross-sectional anode (102a), a second cross-sectional anode (102b), a second separator (101-2), a first cross-sectional cathode (103a), and a second cross-sectional cathode (103b) stacked in this order, and an inactivated region (104) can be formed on one side of the first cross-sectional anode (102a) facing the first separator (101).

[0080] In addition, the area of ​​the negative electrode (102) may be larger than the area of ​​the positive electrode (103) to prevent the reversal of the NP ratio (ratio of negative electrode capacity to positive electrode capacity per unit area) and lithium plating.

[0081] In one example, the width (w) during the inactivation stage can be determined based on the ratio (A / B) of the sum (A) of the surface areas of the plurality of negative electrodes (102) in the electrode assembly (100) to the sum (B) of the surface areas of the plurality of positive electrodes (103).

[0082] The width (w) is determined based on the ratio (A / B), thereby ensuring a minimum inactive region that does not degrade battery performance, and is expected to reduce manufacturing costs consumed for forming the inactive region.

[0083] Specifically, the ratio (A / B) may decrease as the number of mono cells (e.g., the total number of first and second mono cells) in the electrode assembly increases, and may decrease as the area of ​​one surface of the positive electrode and the area of ​​one surface of the negative electrode increase.

[0084] Tables 1 to 3 below show, as examples, the ratio (A / B) according to the increase in the number of mono-cells in the electrode assembly and the area of ​​one surface of the positive electrode and one surface of the negative electrode.

[0085] Here, the area of ​​one side of the positive electrode can be calculated by multiplying the horizontal length of the positive electrode by the vertical length of the positive electrode, and the area of ​​one side of the negative electrode can be calculated by multiplying the horizontal length of the negative electrode by the vertical length of the negative electrode.

[0086] In addition, the total area of ​​one surface of a plurality of negative electrodes (A) can be calculated by multiplying the area of ​​one surface of a negative electrode by the number of negative electrodes, and the total area of ​​one surface of a plurality of positive electrodes (B) can be calculated by multiplying the area of ​​one surface of a positive electrode by the number of positive electrodes.

[0087] The electrode assemblies in Tables 1 and 3 were manufactured by stacking two mono-cells and one half-cell, and in this case, the number of positive electrodes was two and the number of negative electrodes was three.

[0088] The electrode assembly in Table 2 was manufactured by stacking four mono-cells and one half-cell, and at this time, the number of positive electrodes was four and the number of negative electrodes was five.

[0089] In the following Tables 1 to 3, the "number of mono-cells in the electrode assembly" is the total number of first mono-cells (110-1) and second mono-cells (110-2). [Table 1] [Table 2] [Table 3]

[0090] Referring to Tables 1 and 2, it can be seen that when the number of mono-cells in the electrode assembly increases from 2 to 4, the ratio (A / B) decreases from 1.59 to 1.32.

[0091] Also, referring to Tables 1 and 3, if the area of ​​the positive electrode is 12 cm 2 From 160cm 2 The area of ​​the negative electrode increases to 12.71 cm 2 From 162.81cm 2 It was confirmed that the ratio (A / B) decreased from 1.59 to 1.53 when the concentration increased to .

[0092] From Tables 1 to 3, it can be seen that the ratio (A / B) decreases as the number of mono-cells in the electrode assembly increases, and also decreases as the area of ​​one surface of the positive electrode and the area of ​​one surface of the negative electrode increase.

[0093] Furthermore, as the number of monocells in the electrode assembly increases, the ratio of electrodes participating in the main reaction increases, and the ratio of local reactions to the main reaction may decrease.

[0094] Similarly, as the area of ​​one surface of the positive electrode or the area of ​​one surface of the negative electrode increases, the proportion of the electrode participating in the main reaction increases, and the proportion of local reactions relative to the main reaction may decrease. When the proportion of local reactions decreases to a negligible level, passivation may not be necessary.

[0095] Therefore, the ratio (A / B) can be used as an index for quantitatively analyzing the rate of local reaction by being related to the number of monocells in the electrode assembly and the surface area of ​​the electrode, which affect the rate of local reaction.

[0096] The present invention enables quantitative analysis of whether the rate of local reaction is negligible through the ratio (A / B), and based on this, it is possible to form a passivation region of an optimal size that minimizes the use of unnecessary passivation materials.

[0097] In one example, the width (w) in the inactivation step is determined within the range of 1.0X1 to 1.25X1 when the ratio (A / B) is 1.1 or more and less than 1.2, and X1 can be calculated using the following Equation 2:

number

[0098] In the above formula 2, Y1 is the horizontal length of the outermost negative electrode (102-1), and Z1 is the vertical length of the outermost negative electrode (102-1).

[0099] In another example, the width (w) in the inactivation step is determined within the range of 1.0X2 to 1.5X2 when the ratio (A / B) is 1.2 or more, and X2 can be calculated by the following Equation 3:

number

[0100] In the above formula 3, Y2 is the horizontal length of the outermost negative electrode (102-1), and Z2 is the vertical length of the outermost negative electrode (102-1).

[0101] In the above formulas 3 and 4, the horizontal length of the outermost negative electrode (102-1) and the vertical length of the outermost negative electrode (102-1) may be expressed in mm or cm.

[0102] The width (w) is determined differently based on the ratio (A / B), thereby providing an optimal size of the inactivation region (104) where the local reaction to the main reaction is negligible, and minimizing the use of unnecessary inactivation material.

[0103] In one example, the passivation area 104 can be formed by applying insulating tape or coating with an insulating material.

[0104] The insulating material can be coated by various known coating methods such as spray coating, die coating, etc., without limitation.

[0105] The insulating tape may have a polyimide layer formed on one or both sides thereof. The insulating tape having the polyimide layer formed on one or both sides thereof has excellent adhesiveness and insulating properties, and can exhibit excellent effects in passivating the outermost negative electrode (102-1).

[0106] The insulating material may include an epoxy compound or aluminum oxide.

[0107] The present invention also relates to a method for manufacturing an electrode assembly. The method for manufacturing an electrode assembly is a method for manufacturing an electrode assembly in association with the above-described method for passivating the outermost negative electrode. Therefore, detailed description that overlaps with the above content will be omitted below.

[0108] Referring to the drawing, the manufacturing method includes a passivation step of forming a passivation region (104) having a predetermined width (w) along an edge of one side of a first anode (102-1); a step of manufacturing a first mono-cell (110-1) by sequentially stacking a separator (101), a first anode (102-1) having the passivation region (104), a separator (101), and a cathode (103); a step of manufacturing a plurality of second mono-cells (110-2) by sequentially stacking a separator (101), a second anode (102-2) having no passivation region, a separator (101), and a cathode (103); The method includes the steps of stacking one anode (102-1) and a separator (101) in order to fabricate a half cell (130); stacking a plurality of second mono cells (110-2) on a first mono cell (110-1) to fabricate a stack (120); and stacking the half cell (130) on the second mono cell (110-2) disposed on the top of the stack (120) to fabricate an electrode assembly (100), wherein the width (w) in the inactivation step is determined based on the horizontal length of the first anode (102-1), the vertical length of the first anode (102-1), and the number of first and second mono cells (110-1, 110-2).

[0109] In one example, the width (w) in the inactivation step is determined within the range of 0.9P2 to 1.2P2, and P2 can be calculated using the following Equation 4:

number

[0110] In the above formula 4, a2 is the horizontal length of the first negative electrode, b2 is the vertical length of the first negative electrode, and c2 is the number of first and second mono-cells.

[0111] Furthermore, the width (w) during the inactivation step can be determined based on the ratio (A / B) of the total surface area (A) of the plurality of negative electrodes (102) in the electrode assembly (100) to the total surface area (B) of the plurality of positive electrodes (103).

[0112] In one example, the width (w) in the inactivation step is determined within the range of 1.0X3 to 1.25X3 when the ratio (A / B) is 1.1 or more and less than 1.2, and X3 can be calculated using the following Equation 5:

number

[0113] In the above formula 5, Y2 is the horizontal length of the first negative electrode (102-1), and Z2 is the vertical length of the first negative electrode (102-1).

[0114] In another example, the width (w) in the inactivation step is determined within the range of 1.0X4 to 1.5X4 when the ratio (A / B) is 1.2 or more, and X4 can be calculated using the following Equation 6:

number

[0115] In the above formula 6, Y2 is the horizontal length of the first negative electrode (102-1), and Z2 is the vertical length of the first negative electrode (102-1).

[0116] In the above formulas 5 and 6, the horizontal length of the first negative electrode (102-1) and the vertical length of the first negative electrode (102-1) may be expressed in units of mm or cm.

[0117] In one embodiment, before the passivation step, a determination step may be included to determine whether passivation of the first mono-cell (110-1) and the first negative electrode (102-1) in the half-cell (130) is necessary based on the number of first and second mono-cells (110-1, 110-2).

[0118] In the method according to the present invention, when it is determined in the determination step that passivation of the electrode assembly (100) is necessary, the width (w) of the passivation region (104) in the passivation step is determined based on the horizontal length of the first anode (102-1), the vertical length of the first anode (102-1), and the number of first and second monocells (110-1, 110-2). This minimizes the use of material in unnecessary passivation regions while reducing resistance due to local reactions, thereby preventing a decrease in the performance of the battery (lithium secondary battery), and a detailed description of this will be provided below.

[0119] The determination step may determine that passivation of the first mono-cell (110-1) and the first negative electrode (102-1) in the half-cell (130) is necessary when the number of the first and second mono-cells (110-1, 110-2) is less than a predetermined value.

[0120] Specifically, the determination step may determine that passivation of the first mono cell (110-1) and the first negative electrode (102-1) in the half cell (130) is necessary when the number of first and second mono cells (110-1, 110-2) is less than 15.

[0121] That is, when the total number of the first and second mono-cells (110-1, 110-2) is within the range of 2 to 14, the determination step may determine that the first mono-cell (110-1) and the first negative electrode (102-1) in the half-cell (130) need to be passivated.

[0122] In other words, the passivation step according to the method of the present invention can be carried out when manufacturing an electrode assembly in which the total number of first and second monocells (110-1, 110-2) is less than 15, for example, in the range of 2 to 14.

[0123] FIG. 4 is a diagram illustrating the local and main reactions within the electrode assembly during the activation process.

[0124] 4, during the activation process, the first anode (102-1) reacts with the adjacent electrodes to cause a local reaction involved in charge and discharge. Then, a charge and discharge reaction (main reaction) occurs as lithium moves between the electrodes, separator, and electrolyte in the remaining monocell (110) excluding the first anode (102-1).

[0125] In particular, when the number of monocells 110 in the electrode assembly 100 is less than 15, the ratio of local reactions to the main reactions increases to a certain extent, which can lead to unnecessary consumption of electrolyte and unevenness in the electrode assembly, which can increase the resistance in the secondary battery and reduce the output of the secondary battery.

[0126] To solve the above problem, the determination step may determine that passivation of the first mono-cell (110-1) and the first negative electrode (102-1) in the half-cell (130) is necessary when the number of first and second mono-cells (110-1, 110-2) is less than 15, and may perform the passivation step.

[0127] Meanwhile, the determination step may determine that inerting is not necessary when the number of first and second mono-cells (110-1, 110-2) is 15 or more. When the number of first and second mono-cells (110-1, 110-2) is 15 or more, the ratio of local reactions compared to the main reactions decreases below a certain level, and the local reactions are negligible, so there may be no major problem even if inerting is not performed.

[0128] From the viewpoint of the main reaction and the local reaction, the passivation step determines the width (w) of the passivation region (104) based on the horizontal length of the first negative electrode (102-1), the vertical length of the first negative electrode (102-1), and the number of the first and second monocells (110-1, 110-2) according to Equation 2, thereby providing an optimal size of the passivation region (104) where the local reaction relative to the main reaction is negligible, and minimizing unnecessary material consumption in the passivation region (104).

[0129] Furthermore, the method according to the present invention may include a determination step, prior to the passivation step, of determining whether passivation of the first mono-cell (110-1) and the first negative electrode (102-1) in the half-cell (130) is necessary based on the ratio (A / B).

[0130] The inactivation step can form an inactivation region (104) if the determination step determines that inactivation is necessary.

[0131] In the determination step, if the ratio (A / B) is 1.1 or greater, it may be determined that passivation of the first mono-cell (110-1) and the first negative electrode (102-1) in the half-cell (130) is necessary.

[0132] In the method according to the present invention, when it is determined in the determination step that passivation of the electrode assembly (100) is necessary, the width (w) of the passivation region (104) is determined in the passivation step based on the ratio (A / B), thereby minimizing the use of material in unnecessary passivation regions while reducing resistance due to local reactions, thereby preventing a decrease in the performance of the battery (lithium secondary battery).

[0133] 4, during the activation process, the first anode (102-1) reacts with the adjacent electrodes to cause a local reaction involved in charge and discharge. Then, a charge and discharge reaction (main reaction) occurs as lithium moves between the electrodes, separator, and electrolyte in the remaining monocell (110) excluding the first anode (102-1).

[0134] In particular, when the ratio (A / B) is 1.1 or more, the ratio of local reactions compared to the main reaction increases beyond a certain level, which can lead to unnecessary consumption of electrolyte and non-uniformity of the electrode assembly, which can increase the resistance value within the secondary battery and reduce the output power of the secondary battery.

[0135] To solve the above problem, the determining step may determine that the passivation of the first negative electrode (102-1) is necessary when the ratio (A / B) is 1.1 or more, and perform the passivation step.

[0136] On the other hand, the determination step may determine that inactivation is unnecessary when the ratio (A / B) is less than 1.1. When the ratio (A / B) is less than 1.1, the ratio of local reactions compared to the main reaction decreases below a certain level, and the local reactions are negligible, so there may be no major problem even if inactivation is not performed.

[0137] From the viewpoint of the main reaction and the local reaction, the inactivation step determines the width (w) of the inactivation region (104) differently based on the ratio (A / B) according to Equations 5 and 6, thereby providing an optimal size of the inactivation region (104) where the local reaction relative to the main reaction is negligible, and minimizing unnecessary material consumption in the inactivation region (104).

[0138] The present invention also relates to an electrode assembly, which may be produced from the method described above.

[0139] The electrode assembly (100) includes a plurality of positive electrodes (103), a plurality of negative electrodes (102), and a plurality of separators (101), and also includes a pair of outermost negative electrodes (102-1) disposed at the top and bottom, respectively.

[0140] Specifically, the electrode assembly (100) includes a first mono-cell (110-1) in which a separator (101), a first anode (102-1) having a passivation region (104) with a predetermined width (w) formed along one edge thereof, a separator (101), and a cathode (103) are stacked in order; and a second mono-cell (110-1) in which a separator (101), a second anode (102-2), a separator (101), and a cathode (103) are stacked in order on the first mono-cell (110-1). and a half cell (130) stacked on the uppermost second mono-cell (110-2) and including a separator (101), a first anode (102-1) having a passivation region formed thereon, and a separator (101) stacked in that order. The width (w) of the passivation region (104) is in the range of 0.9P2 to 1.2P2, and P2 can be calculated using the following equation 4:

number

[0141] In the above formula 4, a2 is the horizontal length of the first negative electrode, b2 is the vertical length of the first negative electrode, and c2 is the number of first and second mono-cells.

[0142] In one example, the number of the first and second mono-cells (110-1, 110-2) may be less than 15.

[0143] As explained above, if the number of first and second mono cells (110-1, 110-2) is less than 15, problems due to local reactions may occur, so the inactive region (104) must be formed. In this case, the width (w) of the inactive region (104) is determined according to Equation 2, thereby minimizing the use of unnecessary material in the inactive region while preventing problems due to local reactions.

[0144] In one example, the passivation area (104) may include an insulating tape attached along the edge of one side of the first negative electrode (102-1), or an insulating material coated along the edge of the first negative electrode (102-1).

[0145] The insulating material can be coated by various known coating methods such as spray coating, die coating, etc., without limitation.

[0146] The insulating tape may have a polyimide layer formed on one or both sides thereof. The insulating tape having the polyimide layer formed on one or both sides thereof has excellent adhesiveness and insulating properties, and can exhibit excellent effects in passivating the first negative electrode (102-1).

[0147] The insulating material may include an epoxy compound or aluminum oxide.

[0148] The present invention also relates to an electrode assembly, which may be produced from the method described above.

[0149] The electrode assembly (100) includes a plurality of positive electrodes (103), a plurality of negative electrodes (102), and a plurality of separators (101), and also includes a pair of outermost negative electrodes (102-1) disposed at the top and bottom, respectively.

[0150] Specifically, the electrode assembly (100) includes a first mono-cell (110-1) in which a separator (101), a first anode (102-1) having a passivation region (104) with a predetermined width (w) formed along one edge thereof, a separator (101), and a cathode (103) are stacked in this order; a plurality of second mono-cells (110-2) stacked on the first mono-cell (110-1) in which a separator (101), a second anode (102-2), a separator (101), and a cathode (103) are stacked in this order; and a half-cell (130) stacked on the second mono-cell (110-2) in the uppermost position in the stack, in which a separator (101), a first anode (102-1) having a passivation region formed thereon, and a separator (101) are stacked in this order.

[0151] When the ratio (A / B) of the total surface area (A) of the multiple negative electrodes (102) in the electrode assembly to the total surface area (B) of the multiple positive electrodes (103) is 1.1 or more and less than 1.2, the width (w) of the inactivated region (104) is within the range of 1.0x3 to 1.25x3.

[0152] The ratio (A / B) of the total surface area (A) of the plurality of negative electrodes (102) in the electrode assembly to the total surface area (B) of the plurality of positive electrodes (103) is 1.2 or more, and the width (w) of the inactivated region is within the range of 1.0x4 to 1.5x4, The X3 and X4 are calculated by the following Equations 5 and 6, respectively:

number

number

[0153] In the above formulas 5 and 6, Y2 is the horizontal length of the first negative electrode, and Z2 is the vertical length of the first negative electrode.

[0154] An electrode assembly (100) that satisfies the above conditions has an optimum size of the inactive region (104) where the local reaction to the main reaction is negligible.

[0155] In one example, the passivation area 104 can be formed by applying insulating tape or coating with an insulating material.

[0156] The insulating material can be coated by various known coating methods such as spray coating, die coating, etc., without limitation.

[0157] The insulating tape may have a polyimide layer formed on one or both sides thereof. The insulating tape having the polyimide layer formed on one or both sides thereof has excellent adhesiveness and insulating properties, and can exhibit excellent effects in passivating the first negative electrode (102-1).

[0158] The insulating material may include an epoxy compound or aluminum oxide. [Example]

[0159] Hereinafter, the present application will be described in detail through examples, but the scope of the present application is not limited to the following examples.

[0160] Manufacturing example Anode manufacturing Artificial graphite, conductive material, and binder were mixed in a ratio of 94:3:3 to prepare a negative electrode slurry, which was then applied to a copper current collector, dried, and rolled to prepare a negative electrode.

[0161] Cathode manufacturing NCM811, carbon black, and PVDF were mixed in a ratio of 90:5:5 to prepare a positive electrode slurry, which was then applied to an aluminum current collector, dried, and rolled to prepare a positive electrode.

[0162] Separation membrane A polyethylene porous separator was prepared.

[0163] electrolyte An electrolyte solution was prepared by dissolving 1M LiPF6 in a mixed solvent of EC (ethylene carbonate), DMC (dimethyl carbonate) and EMC (ethylmethyl carbonate) in a volume ratio of 3:4:3.

[0164] Example 1A Electrode Assembly The positive electrode and negative electrode produced in the Production Example were cut into pieces of 5×7 cm and 5.1×7.1 cm, respectively.

[0165] Then, an insulating tape was applied along the edge of the negative electrode with a width of 0.5 cm to form an outermost electrode with a passivation area.

[0166] A stack containing a total of five monocells was produced by stacking one first monocell, which was composed of a separator, an outermost negative electrode (inactivated region O), a separator, and a positive electrode stacked in that order, and four second monocells, which were composed of a separator, a negative electrode (inactivated region X), a separator, and a positive electrode stacked in that order.

[0167] Then, a half cell, each having a separator, a negative electrode, and a separator stacked in this order, was stacked on the monocell located at the top of the stack to prepare an electrode assembly.

[0168] The electrode assembly prepared according to Example 1A included five positive electrodes and six negative electrodes.

[0169] In addition, according to the specifications of the electrode assembly manufactured in Example 1A, the P1 value calculated by substituting 5.1 for a1, 7.1 for b1, and 5 for c1 in Equation 1 was 0.424.

[0170] When the P1 value is 0.424, the range of 0.9P1 to 1.2P1 is calculated as 0.382 mm to 0.509 mm, so it was confirmed that the width of the passivation region of the electrode assembly manufactured in Example 1A, 0.5 cm, was within the range of 0.9P1 to 1.2P1.

[0171] Lithium secondary battery The prepared electrode assembly was placed inside a pouch case, and the prepared electrolyte was then injected into the case.

[0172] After pre-aging for 2 days at room temperature, the battery was charged at a charging rate of 0.1C until the SOC reached 30%, and then aged for 1 day each at room temperature and 60°C. After that, a degassing process was performed to remove gas from the case, to manufacture a lithium secondary battery.

[0173] Example 2A An electrode assembly and a lithium secondary battery were fabricated in the same manner as in Example 1, except that an outermost electrode having a passivation area formed by applying insulating tape with a width of 0.35 cm along the edge of the negative electrode was fabricated, and one first mono cell and nine second mono cells were stacked to fabricate a stack having a total of 10 mono cells.

[0174] The electrode assembly prepared according to Example 2A included 10 positive electrodes and 11 negative electrodes.

[0175] In addition, according to the specifications of the electrode assembly manufactured in Example 2A, the P1 value calculated by substituting 5.1 for a1, 7.1 for b1, and 10 for c1 in Equation 1 was 0.297.

[0176] When the P1 value is 0.297, the range of 0.9P1 to 1.2P1 is calculated as 0.267 mm to 0.357 mm, so the width of the passivation region of the electrode assembly manufactured in Example 2A, 0.35 cm, was confirmed to be within the range of 0.9P1 to 1.2P1.

[0177] Comparative Example 1A An electrode assembly and a lithium secondary battery were manufactured in the same manner as in Example 1A, except that five second mono-cells were stacked without the first mono-cell to manufacture a stack including a total of five mono-cells.

[0178] Comparative example 2A An electrode assembly and a lithium secondary battery were manufactured in the same manner as in Example 2A, except that 10 second mono-cells were stacked without the first mono-cell to manufacture a stack including a total of 10 mono-cells.

[0179] Comparative example 3A An electrode assembly and a lithium secondary battery were fabricated in the same manner as in Example 2A, except that a first mono-cell including a first negative electrode having a passivation area formed by treating the edge of the negative electrode with insulating tape in a width of 0.15 cm was fabricated.

[0180] According to the specifications of the electrode assembly manufactured in Comparative Example 3A, the P1 value calculated by substituting 5.1 for a1, 7.1 for b1, and 10 for c1 in Equation 1 was 0.297.

[0181] When the P1 value is 0.297, the range of 0.9P1 to 1.2P1 is calculated as 0.267 mm to 0.357 mm. Therefore, it was confirmed that the width of the passivation region of the electrode assembly manufactured in Comparative Example 3A, 0.15 cm, falls outside the range of 0.9P1 to 1.2P1.

[0182] Comparative example 4A An electrode assembly and a lithium secondary battery were manufactured in the same manner as in Example 1A, except that 15 second mono-cells were stacked without the first mono-cell to manufacture a stack including a total of 15 mono-cells.

[0183] For reference, the electrode assembly prepared according to Comparative Example 4A included 15 positive electrodes and 16 negative electrodes.

[0184] Comparative example 5A An electrode assembly and a lithium secondary battery were fabricated in the same manner as in Example 1A, except that an outermost electrode having a passivation region formed by treating an insulating tape with a width of 0.18 mm along the edge of the negative electrode was fabricated, and one first mono cell and 14 second mono cells were stacked to fabricate a stack including a total of 15 mono cells.

[0185] Experimental Example 1 The lithium secondary batteries manufactured in Examples 1A, 2A, and Comparative Examples 1A to 5A were measured for discharge resistance at SOC50 for 10 seconds, and the results are shown in Table 4 below. [Table 4]

[0186] From the above experimental results, it was confirmed that the lithium secondary batteries manufactured in Examples 1A and 2A had reduced resistance compared to Comparative Examples 1A and 2A. Furthermore, in the case of Comparative Example 3A, when converted to a P1 value calculated according to Equation 1, the width of the passivation region (0.15 mm) did not satisfy the range of 0.9P1 to 1.2P1, and thus the same resistance value was shown as in Comparative Example 2A, which did not have a passivation region, confirming that the effect of the passivation region was not demonstrated.

[0187] Furthermore, from Comparative Examples 4A and 5A, it was confirmed that when the total number of first and second mono cells in the electrode assembly is 15 or more, similar resistance values ​​are exhibited regardless of whether or not the cells are passivated. This indicates that it is not necessary to form a passivation region when the total number of first and second mono cells is 15 or more.

[0188] Experimental Example 2 For a 900 mA small pouch secondary battery, the resistance of the electrode assembly was measured according to the ratio (A / B). The resistance was measured for 10 seconds with a 2.5 C discharge pulse, and the results are shown in Table 5 below. [Table 5]

[0189] In Examples 1B and 2B, imide tape having a width in the range of 1.0X4 to 1.5X4, where X4 is the value calculated from Equation 6, was attached to the edge of the outermost electrode to form a passivation region, while in Comparative Examples 1B and 2B, no passivation region was formed. Examples 1B and 2B exhibited lower resistance values ​​than Comparative Examples 1B and 2B. This confirmed that when the ratio (A / B) is 1.1 or greater and the edge of the outermost electrode is passivated, the involvement of local reactions in the outermost electrode can be prevented.

[0190] The preferred embodiments of the present invention described above have been disclosed for illustrative purposes, and those skilled in the art with ordinary skill in the art may make various modifications, changes, and additions within the spirit and scope of the present invention, and such modifications, changes, and additions should be considered to fall within the scope of the following claims. [Explanation of symbols]

[0191] 100: Electrode assembly 101: Separation membrane 102: Negative electrode 103: Positive electrode 110: Monocell 120: Laminate 130: Half cell 102-1: outermost negative electrode 104: Inactivation area

Claims

1. A method for passivating a pair of outermost negative electrodes disposed at the top and bottom of an electrode assembly including a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators, comprising: A passivation step includes forming a passivation region having a predetermined width (w) along an edge of one surface of the outermost negative electrode; The width (w) in the deactivation step is determined based on the horizontal length of the outermost negative electrode, the vertical length of the outermost negative electrode, and the number of monocells each consisting of a separator, a negative electrode, a separator, and a positive electrode in the electrode assembly.

2. The width (w) in the inactivation step is 0.9P 1 ~1.2P 1 The P 1 is calculated by the following formula 1: [Equation 1] In the above formula 1, a 1 is the horizontal length of the outermost negative electrode, and b 1 is the vertical length of the outermost negative electrode, and c 1 is the number of monocells in the electrode assembly, each consisting of a separator, a negative electrode, a separator, and a positive electrode.

3. 2. The method of claim 1, wherein the width (w) in the passivation step is determined based on a ratio (A / B) of a total surface area (A) of a plurality of negative electrodes in an electrode assembly to a total surface area (B) of a plurality of positive electrodes in an electrode assembly.

4. The width (w) in the inactivation step is 1.0X when the ratio (A / B) is 1.1 or more and less than 1.

2. 1 ~1.25X 1 The X is determined within the range 1 is calculated by the following formula 2: [Equation 2] In the above formula 2, Y 1 is the horizontal length of the outermost negative electrode, and Z 1 is the vertical length of the outermost negative electrode.

5. The width (w) in the inactivation step is 1.0X when the ratio (A / B) is 1.2 or more. 2 ~1.5X 2 The X is determined within the range 2 is calculated by the following formula 3: [Equation 3] In the above formula 3, Y 2 is the horizontal length of the outermost negative electrode, and Z 2 is the vertical length of the outermost negative electrode.

6. The method of claim 1 , wherein the passivation area is formed by attaching an insulating tape or coating an insulating material.

7. The method of claim 6 , wherein the insulating tape has a polyimide layer formed on one or both sides thereof.

8. The method for passivating an outermost negative electrode according to claim 6 , wherein the insulating material comprises an epoxy compound or aluminum oxide.

9. a passivation step of forming a passivation region having a predetermined width (w) along an edge of one surface of the first negative electrode; manufacturing a first mono-cell by sequentially stacking a separator, a first anode having an inactive region formed thereon, a separator, and a cathode; manufacturing a plurality of second mono-cells by sequentially stacking a separator, a second negative electrode having no inactive region formed thereon, a separator, and a positive electrode; a step of sequentially stacking a separator, a first anode having a passivation region formed thereon, and a separator to fabricate a half cell; stacking a plurality of second mono-cells on a first mono-cell to form a stack; and a step of stacking the half-cell on a second mono-cell disposed on the top of the stack to produce an electrode assembly; The width (w) in the inactivation step is determined based on the horizontal length of the first negative electrode, the vertical length of the first negative electrode, and the number of first and second mono-cells in the electrode assembly.

10. The width (w) in the inactivation step is 0.9P 2 ~1.2P 2 The P 2 is calculated by the following formula 4, [Equation 4] In the above formula 4, a 2 is the horizontal length of the first negative electrode, and b 2 is the vertical length of the first negative electrode, and c 2 is the number of first and second mono cells.

11. 10. The method for manufacturing an electrode assembly according to claim 9, wherein the width (w) in the passivation step is determined based on a ratio (A / B) of a total surface area (A) of a plurality of negative electrodes in the electrode assembly to a total surface area (B) of a plurality of positive electrodes in the electrode assembly.

12. The width (w) in the inactivation step is 1.0X when the ratio (A / B) is 1.1 or more and less than 1.

2. 3 ~1.25X 3 The X is determined within the range 3 is calculated by the following formula 5: [Equation 5] In the above formula 5, Y 2 is the horizontal length of the first negative electrode, and Z 2 is the vertical length of the first negative electrode.

13. In the inactivation step, the width (w) in the inactivation step is 1.0X when the ratio (A / B) is 1.2 or more. 4 ~1.5X 4 The X is determined within the range 4 is calculated by the following formula 6: [Equation 6] In the above formula 6, Y 2 is the horizontal length of the first negative electrode, and Z 2 is the vertical length of the first negative electrode.

14. 10. The method for manufacturing an electrode assembly according to claim 9, further comprising, before the passivation step, determining whether passivation of the first mono-cell and the first negative electrode in the half-cell is necessary based on the number of first and second mono-cells.

15. 15. The method of claim 14, wherein the determining step determines that passivation of the first mono-cell and the first negative electrode in the half-cell is necessary when the number of the first and second mono-cells is less than a predetermined value.

16. 15. The method for manufacturing an electrode assembly according to claim 14, wherein the determining step determines that passivation of the first mono-cell and the first negative electrode in the half-cell is necessary when the number of the first and second mono-cells is less than 15.

17. 12. The method for manufacturing an electrode assembly according to claim 11, further comprising, before the passivation step, determining whether passivation of the first negative electrode in the first mono-cell and the half-cell is necessary based on the ratio (A / B).

18. 18. The method for manufacturing an electrode assembly according to claim 17, wherein the determining step determines that passivation of the first negative electrode in the first mono-cell and the half-cell is necessary if the ratio (A / B) is 1.1 or greater.

19. a first mono-cell in which a separator, a first negative electrode having an inactive region with a predetermined width (w) formed along one edge thereof, a separator, and a positive electrode are stacked in this order; a plurality of second mono-cells stacked on the first mono-cell, each having a separator, a second negative electrode, a separator, and a positive electrode stacked in that order; and The half-cell is stacked on a second mono-cell arranged at the top, and includes a separator, a first negative electrode having a passivation region formed thereon, and a separator stacked in that order; The width (w) of the inactivation region is 0.9P 2 ~1.2P 2 is within the range of The above P 2 is calculated by the following equation 4, electrode assembly: [Equation 7] In the above formula 4, a 2 is the horizontal length of the first negative electrode, and b 2 is the vertical length of the first negative electrode, and c 2 is the number of first and second mono cells.

20. a first mono-cell in which a separator, a first negative electrode having an inactive region with a predetermined width (w) formed along one edge thereof, a separator, and a positive electrode are stacked in this order; a plurality of second mono-cells stacked on the first mono-cell, each having a separator, a second negative electrode, a separator, and a positive electrode stacked in that order; and The half-cell is stacked on a second mono-cell arranged at the top, and includes a separator, a first negative electrode having a passivation region formed thereon, and a separator stacked in that order; When the ratio (A / B) of the total surface area (A) of the plurality of negative electrodes to the total surface area (B) of the plurality of positive electrodes in the electrode assembly is 1.1 or more and less than 1.2, the width (w) of the inactivated region is 1.0X 3 ~1.25X 3 is within the range of When the ratio (A / B) of the total surface area (A) of the plurality of negative electrodes to the total surface area (B) of the plurality of positive electrodes in the electrode assembly is 1.2 or more, the width (w) of the inactivated region is 1.0X 4 ~1.5X 4 is within the range of X 3 and X 4 are calculated by the following equations 5 and 6, respectively, for the electrode assembly: [Equation 8] [Equation 9] In the above formulas 5 and 6, Y 2 is the horizontal length of the first negative electrode, and Z 2 is the vertical length of the first negative electrode.

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