Electrode assembly and rechargeable battery comprising same

Abstract

This electrode assembly comprises: a separator; a positive electrode and a negative electrode which are positioned such that the separator is interposed therebetween, and are wound together with the separator; and a compensation layer located on at least one of the positive electrode or the negative electrode. The positive electrode includes a positive electrode body, in which a positive electrode mixture layer is located on a positive electrode substrate, and a positive electrode substrate tab located on one side of the positive electrode body. The negative electrode includes a negative electrode body, in which a negative electrode mixture layer is located on a negative electrode substrate, and a negative electrode substrate tab located on the other side of the negative electrode body. The negative electrode mixture layer includes a capacity reduction unit adjacent to the negative electrode substrate tab. The compensation layer is located on at least one of a portion of the positive electrode body facing the capacity reduction unit or a portion of the negative electrode body corresponding to the capacity reduction unit.

Description

Electrode assembly and secondary battery having the same

[0001] The present disclosure relates to a secondary battery, and more particularly, to an electrode assembly for improving safety and a secondary battery having the same.

[0002] The positive and negative active materials of lithium secondary batteries contain materials capable of reversible intercalation and deintercalation of lithium ions. Lithium ions shuttle between the positive and negative active materials, enabling the charging and discharging of the secondary battery. That is, during charging, lithium ions from the positive active material are inserted into the negative active material, and during discharge, lithium ions are extracted from the negative active material.

[0003] Typically, the capacity of the negative active material must be greater than that of the positive active material to ensure that the negative active material fully accommodates the lithium ions released from the positive active material during charging. If the capacity of the positive active material exceeds that of the negative active material, lithium may precipitate (solidify) on the surface of the negative active material. This lithium precipitation can lead to dendrite growth, damaging the separator and compromising the safety of the electrode assembly.

[0004] The present disclosure aims to provide an electrode assembly having improved safety by preventing lithium ions from being precipitated from the surface of a negative electrode active material, and a secondary battery having the same.

[0005] An electrode assembly according to one embodiment includes a separator, a positive electrode and a negative electrode positioned with the separator interposed therebetween and wound together with the separator, and a compensation layer positioned on at least one of the positive electrode and the negative electrode. The positive electrode includes a positive electrode body having a positive electrode composite layer positioned on a positive electrode substrate, and a positive electrode substrate tab positioned on one side of the positive electrode body. The negative electrode includes a negative electrode body having a negative electrode composite layer positioned on a negative electrode substrate, and a negative electrode substrate tab positioned on the other side of the negative electrode body. The negative electrode composite layer includes a capacity-reducing portion adjacent to the negative electrode substrate tab. The compensation layer is positioned on at least one of a portion of the positive electrode body facing the capacity-reducing portion and a portion of the negative electrode body corresponding to the capacity-reducing portion.

[0006] The compensation layer may be positioned between the positive electrode substrate and the positive electrode composite layer in a portion of the positive electrode body facing the capacity reduction portion, and may include a material that does not participate in the battery reaction. The compensation layer may be composed of a binder layer, and may be positioned parallel to the longitudinal direction of the positive electrode substrate, having a preset thickness and a preset width.

[0007] On the other hand, the compensation layer may be positioned between the negative electrode substrate and the capacity reduction portion and may include a negative electrode active material. The compensation layer may be composed of a silicon layer, and may have a preset thickness and a preset width and may be positioned parallel to the longitudinal direction of the negative electrode substrate.

[0008] On the other hand, the compensation layer may include a first compensation layer and a second compensation layer. The first compensation layer may be positioned between the positive electrode substrate and the positive electrode composite layer in a portion of the positive electrode body facing the capacity-reducing portion, and may include a material that does not participate in the battery reaction. The second compensation layer may be positioned between the negative electrode substrate and the capacity-reducing portion, and may include a negative electrode active material. The first compensation layer may be composed of a binder layer, and the second compensation layer may be composed of a silicon layer.

[0009] The positive and negative electrodes may have an NP ratio greater than 1 in a portion of the positive electrode body facing the capacity reduction portion and in a portion of the negative electrode body corresponding to the capacity reduction portion.

[0010] According to another embodiment, an electrode assembly includes a separator, a cathode and anode positioned with the separator interposed therebetween and wound together with the separator, and a compensation layer positioned on the cathode. The cathode includes a cathode body having a cathode composite layer positioned on a cathode substrate, and a cathode substrate tab positioned on one side of the cathode body. The anode includes a cathode body having a cathode composite layer positioned on a cathode substrate, and a cathode substrate tab positioned on the other side of the cathode body. The cathode composite layer includes a capacity reduction portion adjacent to the cathode substrate tab. The compensation layer is positioned between the cathode substrate and the cathode composite layer in a portion of the cathode body facing the capacity reduction portion. The cathode composite layer has a thickness reduced by a thickness of the compensation layer.

[0011] The compensation layer may be composed of a binder layer. The positive and negative electrodes may have an NP ratio greater than 1 in a portion of the positive electrode body facing the capacity-reducing portion and in a portion of the negative electrode body corresponding to the capacity-reducing portion.

[0012] According to another embodiment, an electrode assembly includes a separator, a positive electrode and a negative electrode positioned with the separator interposed therebetween and wound together with the separator, and a compensation layer positioned on the negative electrode. The positive electrode includes a positive electrode body having a positive electrode composite layer positioned on a positive electrode substrate, and a positive electrode substrate tab positioned on one side of the positive electrode body. The negative electrode includes a negative electrode body having a negative electrode composite layer positioned on a negative electrode substrate, and a negative electrode substrate tab positioned on the other side of the negative electrode body. The negative electrode composite layer includes a capacity reduction portion adjacent to the negative electrode substrate tab. The compensation layer is positioned between the negative electrode substrate and the capacity reduction portion, includes a negative electrode active material, and increases the capacity of the negative electrode active material in the negative electrode body corresponding to the capacity reduction portion.

[0013] The compensation layer may be composed of a silicon layer. The positive and negative electrodes may have an NP ratio greater than 1 in a portion of the positive electrode body facing the capacity-reducing portion and in a portion of the negative electrode body corresponding to the capacity-reducing portion.

[0014] A secondary battery according to one embodiment includes an electrode assembly, a can accommodating the electrode assembly and an electrolyte in an internal space, and a cap plate coupled to an open end of the can to seal the can. The electrode assembly includes a positive electrode and a negative electrode that are laminated and wound with a separator therebetween, and a compensation layer positioned on at least one of the positive electrode and the negative electrode. The positive electrode includes a positive electrode body having a positive electrode composite layer positioned on a positive electrode substrate, and a positive electrode substrate tab positioned on one side of the positive electrode body. The negative electrode includes a negative electrode body having a negative electrode composite layer positioned on a negative electrode substrate, and a negative electrode substrate tab positioned on the other side of the negative electrode body. The negative electrode composite layer includes a capacity-reducing portion adjacent to the negative electrode substrate tab. The compensation layer is positioned on at least one of a portion of the positive electrode body facing the capacity-reducing portion and a portion of the negative electrode body corresponding to the capacity-reducing portion.

[0015] The compensation layer may be positioned between the positive electrode substrate and the positive electrode composite layer in a portion of the positive electrode body facing the capacity reduction portion, and may include a material that does not participate in the battery reaction. The positive electrode composite layer may have a thickness reduced by the thickness of the compensation layer.

[0016] On the other hand, the compensation layer may be positioned between the negative electrode substrate and the capacity reduction portion, may include a negative electrode active material, and may increase the capacity of the negative electrode active material in the negative electrode body corresponding to the capacity reduction portion.

[0017] On the other hand, the compensation layer may include a first compensation layer and a second compensation layer. The first compensation layer may be located between the positive electrode substrate and the positive electrode composite layer in a portion of the positive electrode body facing the capacity-reducing portion, and may include a material that does not participate in the battery reaction. The second compensation layer may be located between the negative electrode substrate and the capacity-reducing portion, and may include a negative electrode active material, and may increase the capacity of the negative electrode active material in the negative electrode body corresponding to the capacity-reducing portion.

[0018] The electrode assembly may have an NP ratio greater than 1 in a portion of the positive electrode body facing the capacity reduction portion and a portion of the negative electrode body corresponding to the capacity reduction portion.

[0019] In a secondary battery according to an embodiment, the electrode assembly can suppress lithium precipitation and subsequent dendrite formation in a capacity-reducing region of the negative electrode composite layer by using a compensation layer. Accordingly, internal short circuits in the electrode assembly can be prevented, thereby improving the durability and safety of the secondary battery.

[0020] Figure 1 is a schematic diagram showing a winding process of an electrode assembly according to the first embodiment.

[0021] Fig. 2 is a plan view showing the unfolded state of the positive electrode in the electrode assembly according to the first embodiment.

[0022] Figure 3 is a cross-sectional view taken along line AA of Figure 2.

[0023] Figure 4 is a schematic cross-sectional view showing the manufacturing process of the anode illustrated in Figure 3.

[0024] Fig. 5 is a plan view showing the unfolded state of the cathode in the electrode assembly according to the first embodiment.

[0025] Figure 6 is a cross-sectional view taken along the BB line of Figure 5.

[0026] Figure 7 is a schematic cross-sectional view showing the manufacturing process of the cathode illustrated in Figure 6.

[0027] Fig. 8 is a partially enlarged cross-sectional view of an electrode assembly according to the first embodiment.

[0028] Figure 9 is a partially enlarged view of Figure 8.

[0029] Fig. 10 is a partially enlarged cross-sectional view of an electrode assembly according to the second embodiment.

[0030] Figure 11 is a partially enlarged view of Figure 10.

[0031] Fig. 12 is a partially enlarged cross-sectional view of an electrode assembly according to a third embodiment.

[0032] Figure 13 is a perspective view of a secondary battery according to one embodiment.

[0033] Figure 14 is a cross-sectional view of the secondary battery illustrated in Figure 13.

[0034] Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0035] Figure 1 is a schematic diagram showing a winding process of an electrode assembly according to the first embodiment.

[0036] Referring to Fig. 1, the electrode assembly of the present embodiment may be a rolled electrode assembly for a cylindrical battery. The electrode assembly may be configured such that a positive electrode (110) and a negative electrode (120) are laminated and rolled with a separator (130) interposed therebetween. Each of the positive electrode (110), the negative electrode (120), and the separator (130) may be configured in a strip shape extending long along the rolling direction.

[0037] The electrode assembly may be configured such that a cathode (120), a separator (130), an anode (110), and a separator (130) are sequentially stacked and then wound in a circular shape around a center pin (101). At this time, the cathode (120) may be positioned closer to the center pin (101) than the anode (110), but the arrangement of the anode (110) and the cathode (120) is not limited to the illustrated example. The center pin (101) may remain in the electrode assembly or may be removed from the electrode assembly after the electrode assembly is wound.

[0038] Fig. 2 is a plan view showing the unfolded state of the positive electrode in the electrode assembly according to the first embodiment, and Fig. 3 is a cross-sectional view taken along line AA of Fig. 2.

[0039] Referring to FIGS. 2 and 3, the anode (110) may include an anode body (10) having a cathode composite layer (12) positioned on a cathode substrate (11), and an anode substrate tab (20) positioned on one side (upper side based on the drawing) of the cathode body (10). A portion of the cathode substrate (11) may be covered with the cathode composite layer (12) to form the cathode body (10) together with the cathode composite layer (12). The remainder of the cathode substrate (11) may not be covered with the cathode composite layer (12), and its surface may be exposed to form the cathode substrate tab (20).

[0040] The positive electrode composite layer (12) has a constant width and can be positioned parallel to the longitudinal direction (horizontal direction based on the drawing) of the positive electrode (110). The positive electrode substrate tab (20) is a portion to be fixed to the positive electrode current collector (not shown) and has the function of collecting the current of the positive electrode body (10) and transmitting it to the positive electrode current collector. The positive electrode substrate tab (20) is provided with a plurality of cutting lines (21) so that the positive electrode substrate tab (20) can be divided into a plurality of pieces.

[0041] The positive electrode substrate (11) may be composed of a metal sheet having excellent electrical conductivity, such as aluminum foil or aluminum mesh. The positive electrode composite layer (12) may be manufactured by a process of manufacturing a slurry containing a positive electrode active material, a conductive agent, a binder, etc., applying the slurry to both sides of the positive electrode substrate (11), and drying and compressing the applied slurry. The positive electrode substrate (11) provides a path for the movement of charges generated in the positive electrode composite layer (12) and supports the positive electrode composite layer (12).

[0042] The cathode active material may be composed of a compound capable of reversible intercalation and deintercalation of lithium, and specifically may include at least one compound oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. For example, the cathode active material may include a transition metal oxide such as LiCoO2, LiNiO2, LiMn2O4, Li(NiCoAl)O2, LiFePO4, or Li(NiCoMn)O2.

[0043] Figure 4 is a schematic cross-sectional view showing the manufacturing process of the anode illustrated in Figure 3.

[0044] Referring to FIGS. 3 and 4, the anode (110) can be manufactured by preparing a cathode base material (30) having cathode base tabs (20) on both left and right sides, applying slurry to the central area of ​​the cathode base material (30) excluding the cathode base tabs (20), drying, and compressing to manufacture a cathode composite layer (12), and cutting the central portion of the cathode base material (30) and the cathode composite layer (12) to separate them into two cathodes (110). This process is called a stripe coating method, and can increase the manufacturing efficiency of the electrode assembly.

[0045] At this time, the slurry is discharged from a die (not shown) facing the center of the positive electrode base material (30) and then spreads to both sides toward the two positive electrode base tabs (20). Due to this process characteristic, the thickness of the positive electrode composite layer (12) may decrease in the area close to the positive electrode base tabs (20), resulting in a decrease in the loading level (weight of slurry per unit area). In FIGS. 3 and 4, reference numeral 140 denotes a compensation layer, which will be described later.

[0046] Fig. 5 is a plan view showing the unfolded state of the cathode in the electrode assembly according to the first embodiment, and Fig. 6 is a cross-sectional view taken along the line BB of Fig. 5.

[0047] Referring to FIGS. 5 and 6, the negative electrode (120) may include a negative electrode body (50) having a negative electrode composite layer (52) positioned on a negative electrode substrate (51), and a negative electrode substrate tab (60) positioned on the other side (lower side based on the drawing) of the negative electrode body (50). A portion of the negative electrode substrate (51) may be covered with the negative electrode composite layer (52) to form the negative electrode body (50) together with the negative electrode composite layer (52). The remainder of the negative electrode substrate (51) may not be covered with the negative electrode composite layer (52) and its surface may be exposed to form the negative electrode substrate tab (60).

[0048] The negative electrode composite layer (52) has a constant width and can be positioned parallel to the longitudinal direction (horizontal direction based on the drawing) of the negative electrode (120). The negative electrode substrate tab (60) is a portion to be fixed to the negative electrode current collector (not shown) and has the function of collecting the current of the negative electrode body (50) and transmitting it to the negative electrode current collector. The negative electrode substrate tab (60) is provided with a plurality of cutting lines (61) so that the negative electrode substrate tab (60) can be divided into a plurality of pieces.

[0049] The negative electrode substrate (51) may be composed of a metal sheet having excellent electrical conductivity, such as copper foil, copper mesh, nickel foil, or nickel mesh. The negative electrode composite layer (52) may be manufactured by a process of manufacturing a slurry containing a negative electrode active material, a conductive material, a binder, etc., applying the slurry to both sides of the negative electrode substrate (51), and drying and compressing the applied slurry. The negative electrode substrate (51) provides a path for the movement of charges generated in the negative electrode composite layer (52) and supports the negative electrode composite layer (52).

[0050] The negative active material may include a material capable of reversible intercalation and deintercalation of lithium ions, such as a carbon-based material and silicon. The carbon-based material may include at least one of crystalline carbon and amorphous carbon, and at least one of natural graphite and artificial graphite.

[0051] Figure 7 is a schematic cross-sectional view showing the manufacturing process of the cathode illustrated in Figure 6.

[0052] Referring to FIGS. 6 and 7, the negative electrode (120) can be manufactured by preparing a negative electrode base material (70) having negative electrode base tabs (60) on both left and right sides, applying slurry to the central area of ​​the negative electrode base material (70) excluding the negative electrode base tabs (60), drying, and compressing to manufacture a negative electrode composite layer (52), and cutting the central portion of the negative electrode base material (70) and the negative electrode composite layer (52) to separate them into two negative electrodes (120).

[0053] At this time, the slurry is discharged from a die (not shown) facing the center of the negative electrode base material (70) and then spreads to both sides toward the two negative electrode substrate tabs (60). Due to this process characteristic, the negative electrode composite layer (52) may have a thickness that decreases in a region close to the negative electrode substrate tabs (60), thereby causing a decrease in the loading level (weight of slurry per unit area). In other words, the negative electrode composite layer (52) may not maintain a constant thickness and may include a capacity reduction portion (53) in which the thickness gradually decreases and the capacity decreases.

[0054] Fig. 8 is a partially enlarged cross-sectional view of an electrode assembly according to the first embodiment, and Fig. 9 is a partially enlarged view of Fig. 8.

[0055] Referring to FIGS. 8 and 9, the positive electrode substrate tab (20) and the negative electrode substrate tab (60) in the electrode assembly (100) are positioned on opposite sides. The drawing illustrates a case where the positive electrode substrate tab (20) is positioned on the upper side and the negative electrode substrate tab (60) is positioned on the lower side. The separator (130) may be composed of a porous substrate coated with a binder on at least one surface, and insulates the positive electrode (110) and the negative electrode (120) while allowing the movement of lithium ions.

[0056] During the winding process of the electrode assembly (100), the positive electrode substrate tab (20) and the negative electrode substrate tab (60) can be first bent toward the winding center of the electrode assembly (100) by being pushed by high-pressure air, and after the winding of the electrode assembly (100), can be secondarily bent by being pressed by a jig (not shown). Each of the positive electrode substrate tab (20) and the negative electrode substrate tab (60) can be flattened so as to overlap with portions located inside thereof by the second bending.

[0057] In the electrode assembly (100), lithium ions move back and forth between the positive electrode active material and the negative electrode active material, thereby enabling charging and discharging of the secondary battery. That is, during charging, lithium ions from the positive electrode active material are inserted into the negative electrode active material, and during discharging, lithium ions are extracted from the negative electrode active material. The capacity of the negative electrode (120) is set to be greater than that of the positive electrode (110) so that the negative electrode active material can fully accommodate the lithium ions released from the positive electrode active material during charging.

[0058] The NP ratio of the electrode assembly (100) is a value obtained by dividing the capacity per unit area of ​​the negative electrode (120) by the capacity per unit area of ​​the positive electrode (110), and is set to be greater than 1. For example, the NP ratio may be in the range of 1.1 to 1.2, but is not limited to this example. When manufacturing the negative electrode (120), the loading level of the negative electrode composite layer (52) can be appropriately adjusted so that the NP ratio has a value greater than 1.

[0059] Nonetheless, since the negative electrode composite layer (52) includes a capacity reduction region (53) due to the process characteristics described above, the capacity reduction region (53) can be said to be an area with a high risk of lithium precipitation. In general, if the negative electrode active material cannot fully accommodate the lithium ions released from the positive electrode active material due to a decrease in the capacity of the negative electrode, and some of the lithium ions cannot enter the negative electrode active material, lithium may precipitate (solidify) on the surface of the negative electrode composite layer and grow in a dendrite shape.

[0060] The electrode assembly (100) of the present embodiment may include a compensation layer (140) positioned on the positive electrode (110). The compensation layer (140) may be positioned on a portion (lower portion) of the positive electrode body (10) facing the capacity reduction portion (53), and reduces the capacity of the positive electrode active material in the portion of the positive electrode body (10) facing the capacity reduction portion (53). The compensation layer (140) may be positioned between the positive electrode substrate (11) and the positive electrode composite layer (12), and may be provided on the positive electrode substrate (11) before the positive electrode composite layer (12).

[0061] The compensation layer (140) may be composed of a conductive layer or a non-conductive layer that does not participate in the battery reaction, and may be composed of, for example, a binder layer. The binder layer may include a polyvinylidene fluoride-based compound, but is not limited to this example. The compensation layer (140) may have a preset thickness and a preset width and may be positioned parallel to the longitudinal direction of the positive electrode (110).

[0062] The compensation layer (140) reduces the volume of the positive electrode composite layer (12) overlapping with itself by the volume it occupies, thereby reducing the capacity of the positive electrode active material. The electrode assembly (100) can implement an NPV greater than 1 in the capacity reduction portion (53) and a portion of the lower side of the positive electrode body (10) facing it by appropriately adjusting the width and thickness of the compensation layer (140). The compensation layer (140) provided on the positive electrode (110) has a compensatory function of reducing the capacity of the positive electrode active material and increasing the NPV.

[0063] The electrode assembly (100) of the present embodiment can prevent lithium precipitation from occurring in the capacity reduction portion (53) by using the compensation layer (140), and as a result, can improve safety by preventing dendritic growth and subsequent damage to the separator (130).

[0064] Referring again to FIG. 4, the compensation layer (140) may be positioned at the center of the positive electrode base material (30), and the positive electrode composite layer (12) may be fabricated over the positive electrode base material (30) on which the compensation layer (140) is positioned. Thereafter, the central portion of the positive electrode base material (30), the compensation layer (140), and the positive electrode composite layer (12) may be cut to separate them into two positive electrodes (110). The compensation layer (140) may be positioned in contact with the cut surface of the positive electrode (110) created by the cutting.

[0065] Fig. 10 is a partially enlarged cross-sectional view of an electrode assembly according to a second embodiment, and Fig. 11 is a partially enlarged view of Fig. 10. The electrode assembly of the second embodiment has the same or similar configuration as the first embodiment described above, except for the configuration described below.

[0066] Referring to FIGS. 10 and 11, the electrode assembly (100A) of the present embodiment may include a compensation layer (150) positioned on the negative electrode (120). The compensation layer (150) may be positioned in contact with the capacity reduction portion (53) of the negative electrode composite layer (52). Specifically, the compensation layer (150) may be positioned between the negative electrode substrate (51) and the capacity reduction portion (53), and may be provided on the negative electrode substrate (51) before the negative electrode composite layer (52).

[0067] The compensation layer (150) may include a negative electrode active material and may be composed of, for example, a silicon layer. The compensation layer (150) may have a preset thickness and a preset width and may be positioned parallel to the longitudinal direction of the negative electrode (120). Since the compensation layer (150) is provided on the negative electrode substrate (51) before the negative electrode composite layer (52), the slurry for manufacturing the negative electrode composite layer (52) may rise over the compensation layer (150) and cover the compensation layer (150).

[0068] The compensation layer (150) including the negative electrode active material increases the capacity of the negative electrode active material in the negative electrode body (50) corresponding to the capacity reduction portion (53). The electrode assembly (100A) can implement an NPV greater than 1 in the capacity reduction portion (53) and a lower portion of the positive electrode body (10) facing it by appropriately adjusting the width and thickness of the compensation layer (150). The compensation layer (150) provided on the negative electrode (120) has a compensatory function of increasing the capacity of the negative electrode active material and thus increasing the NPV.

[0069] Fig. 12 is a partially enlarged cross-sectional view of an electrode assembly according to a third embodiment. The electrode assembly of the third embodiment has a configuration identical or similar to that of the first and second embodiments described above, except for the configuration described below.

[0070] Referring to FIG. 12, the electrode assembly of the present embodiment may include a first compensation layer (161) positioned at the positive electrode (110) and a second compensation layer (162) positioned at the negative electrode (120). The first compensation layer (161) may have the same configuration as the compensation layer (140) of the first embodiment described above, and the second compensation layer (162) may have the same configuration as the compensation layer (150) of the second embodiment described above.

[0071] The first compensation layer (161) reduces the volume of the positive electrode composite layer (12) overlapping with itself by the volume it occupies, thereby reducing the capacity of the positive electrode active material. The second compensation layer (162) including the negative electrode active material increases the capacity of the negative electrode active material in the negative electrode body (50) corresponding to the capacity reduction portion (53). By the first and second compensation layers (161, 162), the NPV can be a value greater than 1 in the capacity reduction portion (53) and a portion of the lower side of the positive electrode body (10) facing it.

[0072] FIG. 13 is a perspective view of a secondary battery according to one embodiment, and FIG. 14 is a cross-sectional view of the secondary battery illustrated in FIG. 13.

[0073] Referring to FIGS. 13 and 14, the secondary battery of the present embodiment may include an electrode assembly (100), a can (200) that accommodates the electrode assembly (100) and an electrolyte in an internal space, and a cap plate (300) that is coupled to an open end of the can (200) to seal the can (200). The electrode assembly (100) is an electrode assembly according to any one of the first to third embodiments described above.

[0074] A positive electrode collector plate (400) fixed to a positive electrode substrate tab (20) may be positioned on one side (upper side based on the drawing) of the electrode assembly (100), and a negative electrode collector plate (500) fixed to a negative electrode substrate tab (60) may be positioned on the other side (lower side based on the drawing) of the electrode assembly (100).

[0075] The can (200) is formed in a shape in which one side (bottom) is open so that the electrode assembly (100) and the positive and negative electrode collector plates (400, 500) can be inserted. The can (200) may include a circular top portion (210) and a cylindrical side portion (220) connected to the edge of the top portion (210). The top portion (210) may be referred to as the bottom portion when the secondary battery is turned upside down.

[0076] A terminal hole may be located at the center of the top portion (210), and a rivet terminal (700) may be installed in the terminal hole via a first insulator (601). The first insulator (601) insulates the top portion (210) and the rivet terminal (700), and seals the terminal hole to prevent leakage of electrolyte. The rivet terminal (700) may be connected to the positive electrode collector plate (400) and may be charged with the same polarity as the positive electrode, and may function as a positive electrode terminal.

[0077] After the electrode assembly (100) and the positive and negative electrode collector plates (400, 500) are accommodated inside the can (200), the side (220) can be formed to have a beading portion (230) by conventional press processing. The beading portion (230) is a portion that is sunken toward the inside of the can (200) and has the function of suppressing movement of the electrode assembly (100).

[0078] The negative electrode collector plate (500) may include a conductive portion (510) that is in close contact with the inner surface of the beading portion (230). The conductive portions (510) may be provided in multiple numbers along the edge of the negative electrode collector plate (500). The can (200) may be charged with the same polarity as the negative electrode by the conductive portion (510) and may function as a negative electrode terminal. At this time, a second insulator (602) may be positioned between the top portion (210) and the positive electrode collector plate (400) to insulate the top portion (210) and the positive electrode collector plate (400).

[0079] The side portion (220) can be formed to have a crimping portion (240) by conventional press processing. The crimping portion (240) can be a portion in which the opening-side end of the side portion (220) is vertically bent toward the inside of the can (200). The edge of the cap plate (300) can be pressed between the beading portion (230) and the crimping portion (240) via the third insulator (603). The cap plate (300) can be electrically non-polar by being insulated from the positive and negative electrodes.

[0080] A notch groove (310) may be positioned on the inner surface of the cap plate (300). The notch groove (310) may have a V-shaped cross-section, and may be an arc shape on a plane (when the target object is viewed from above). The internal temperature of a secondary battery may rise due to various reasons such as rapid charging and discharging, external impact, exposure to a high-temperature environment, etc., and the internal pressure may rise due to evaporation of the electrolyte, etc. When the internal pressure of the secondary battery rises, the cap plate (300) may break around the notch groove (310) to release internal gas.

[0081] In the secondary battery of the aforementioned configuration, the electrode assembly (100) can suppress lithium precipitation on the surface of the negative electrode composite layer and subsequent dendrite formation by using a compensation layer. Accordingly, internal short circuits in the electrode assembly (100) can be prevented, thereby improving the durability and safety of the secondary battery.

[0082] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

Claims

1. Separator; An anode and a cathode positioned with the separator between them and wound together with the separator; and A compensation layer positioned at least on one of the positive electrode and the negative electrode, The above anode includes an anode body having an anode composite layer positioned on an anode substrate, and an anode substrate tab positioned on one side of the anode body, The above cathode includes a cathode body having a cathode composite layer positioned on a cathode substrate, and a cathode substrate tab positioned on the other side of the cathode body, and the cathode composite layer includes a capacity reducing portion adjacent to the cathode substrate tab. An electrode assembly in which the compensation layer is located on at least one of a portion of the positive electrode body facing the capacity reduction portion and a portion of the negative electrode body corresponding to the capacity reduction portion.

2. In paragraph 1, An electrode assembly in which the compensation layer is located between the positive electrode substrate and the positive electrode composite layer in a portion of the positive electrode body facing the capacity reduction portion, and includes a material that does not participate in a battery reaction.

3. In paragraph 2, The above compensation layer is composed of a binder layer, and is an electrode assembly having a preset thickness and a preset width and positioned parallel to the longitudinal direction of the positive electrode substrate.

4. In paragraph 1, An electrode assembly comprising a negative electrode active material, wherein the compensation layer is positioned between the negative electrode substrate and the capacity reduction portion.

5. In paragraph 4, The above compensation layer is composed of a silicon layer, and is an electrode assembly having a preset thickness and a preset width and positioned parallel to the longitudinal direction of the negative electrode substrate.

6. In paragraph 1, The above compensation layer is, A first compensation layer located between the positive electrode substrate and the positive electrode composite layer in a portion of the positive electrode body facing the capacity reduction portion, and including a material that does not participate in the battery reaction; and An electrode assembly comprising a second compensation layer positioned between the negative electrode substrate and the capacity reducing portion and including a negative electrode active material.

7. In paragraph 6, The above first compensation layer is composed of a binder layer, An electrode assembly wherein the second compensation layer is composed of a silicon layer.

8. In paragraph 1, An electrode assembly in which the positive electrode and the negative electrode have an NP ratio greater than 1 in a portion of the positive electrode body facing the capacity reduction portion and in a portion of the negative electrode body corresponding to the capacity reduction portion.

9. Separator; An anode and a cathode positioned with the separator between them and wound together with the separator; and Includes a compensation layer located at the above anode, The above anode includes an anode body having an anode composite layer positioned on an anode substrate, and an anode substrate tab positioned on one side of the anode body, The above cathode includes a cathode body having a cathode composite layer positioned on a cathode substrate, and a cathode substrate tab positioned on the other side of the cathode body, and the cathode composite layer includes a capacity reducing portion adjacent to the cathode substrate tab. An electrode assembly in which the compensation layer is located between the anode substrate and the anode composite layer in a portion of the anode body facing the capacity reduction portion, and the anode composite layer has a thickness reduced by the thickness of the compensation layer.

10. In paragraph 9, The above compensation layer is composed of a binder layer, An electrode assembly in which the positive electrode and the negative electrode have an NP ratio greater than 1 in a portion of the positive electrode body facing the capacity reduction portion and in a portion of the negative electrode body corresponding to the capacity reduction portion. 11.Separator; An anode and a cathode positioned with the separator between them and wound together with the separator; and Includes a compensation layer located on the above cathode, The above anode includes an anode body having an anode composite layer positioned on an anode substrate, and an anode substrate tab positioned on one side of the anode body, The above cathode includes a cathode body having a cathode composite layer positioned on a cathode substrate, and a cathode substrate tab positioned on the other side of the cathode body, and the cathode composite layer includes a capacity reducing portion adjacent to the cathode substrate tab. An electrode assembly in which the compensation layer is positioned between the negative electrode substrate and the capacity reduction portion, includes a negative electrode active material, and increases the capacity of the negative electrode active material in the negative electrode body corresponding to the capacity reduction portion.

12. In paragraph 11, The above compensation layer is composed of a silicon layer, An electrode assembly in which the positive electrode and the negative electrode have an NP ratio greater than 1 in a portion of the positive electrode body facing the capacity reduction portion and in a portion of the negative electrode body corresponding to the capacity reduction portion.

13. An electrode assembly comprising a positive electrode and a negative electrode laminated and wound with a separator between them, and a compensation layer positioned on at least one of the positive electrode and the negative electrode; A can containing the electrode assembly and electrolyte in an internal space; and A cap plate is included that is joined to the opening end of the can to seal the can, The above anode includes an anode body having an anode composite layer positioned on an anode substrate, and an anode substrate tab positioned on one side of the anode body, The above cathode includes a cathode body having a cathode composite layer positioned on a cathode substrate, and a cathode substrate tab positioned on the other side of the cathode body, and the cathode composite layer includes a capacity reducing portion adjacent to the cathode substrate tab. A secondary battery in which the compensation layer is located on at least one of a portion of the positive electrode body facing the capacity reduction portion and a portion of the negative electrode body corresponding to the capacity reduction portion.

14. In paragraph 13, The compensation layer is located between the positive electrode substrate and the positive electrode composite layer in a portion of the positive electrode body facing the capacity reduction portion, and includes a material that does not participate in the battery reaction. A secondary battery in which the above-mentioned positive electrode composite layer has a thickness reduced by the thickness of the above-mentioned compensation layer.

15. In paragraph 13, A secondary battery in which the compensation layer is positioned between the negative electrode substrate and the capacity reduction portion, includes a negative electrode active material, and increases the capacity of the negative electrode active material in the negative electrode body corresponding to the capacity reduction portion.

16. In paragraph 13, The above compensation layer is, A first compensation layer located between the positive electrode substrate and the positive electrode composite layer in a portion of the positive electrode body facing the capacity reduction portion, and including a material that does not participate in the battery reaction; and A secondary battery comprising a second compensation layer positioned between the negative electrode substrate and the capacity reduction portion, including a negative electrode active material, and increasing the capacity of the negative electrode active material in the negative electrode body corresponding to the capacity reduction portion.

17. In paragraph 13, A secondary battery in which the electrode assembly has an NP ratio greater than 1 in a portion of the positive electrode body facing the capacity reduction portion and a portion of the negative electrode body corresponding to the capacity reduction portion.

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