Electrode assembly
By using active materials with different component ratios or amounts in the electrode assembly and bonding them in the uncoated parts of the electrode sheet, the capacity per unit area of the positive and negative electrodes is adjusted, which solves the problem of N/P ratio imbalance in cylindrical electrode assemblies and improves the stability and lifespan of the electrode assembly.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LG ENERGY SOLUTION LTD
- Filing Date
- 2021-07-16
- Publication Date
- 2026-07-07
AI Technical Summary
In cylindrical electrode assemblies, there is an imbalance in the N/P ratio (capacity ratio per unit area of the positive and negative electrodes) between the region near the central hole and the outer region, which leads to accelerated electrode degradation and affects the lifespan of the secondary battery.
The positive and negative electrodes consist of first and second electrodes, respectively. By applying active materials with different component ratios or different amounts to the surface of the electrodes and bonding them in the uncoated areas, the capacity per unit area is adjusted to reduce the deviation of the N/P ratio.
By adjusting the capacity per unit area of the positive and negative electrodes, the N/P ratio deviation between the area near the central hole and the outer region is reduced, thereby improving the stability and lifespan of the electrode assembly.
Smart Images
Figure CN115803924B_ABST
Abstract
Description
[0001] Cross-reference to related applications
[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2020-0088408, filed on July 16, 2020, and Korean Patent Application No. 10-2021-0093046, filed on July 15, 2021, the entire contents of which are incorporated herein by reference. Technical Field
[0003] The present invention relates to an electrode assembly wound in a state of alternating stacking of electrodes and spacers, and more particularly to an electrode assembly in which the deviation of the N / P ratio (the ratio of the capacity per unit area of the positive and negative electrodes) near the center hole and near the outer edge is reduced to achieve more stable performance. Background Technology
[0004] Batteries that store electrical energy can generally be divided into primary batteries and secondary batteries. A primary battery is a disposable, consumable battery. On the other hand, a secondary battery is a rechargeable battery made using materials in which oxidation and reduction processes between current and materials are repeatable. That is, electricity is generated when a reduction reaction is performed on the material by current, and electricity is discharged when an oxidation reaction is performed on the material by current. Here, this charging and discharging process is repeated.
[0005] Among various types of secondary batteries, lithium secondary batteries are typically manufactured by mounting an electrode assembly, in which a positive electrode (cathode), separators, and a negative electrode (anode) are stacked within a casing. Here, the lithium secondary battery is charged and discharged as the process of lithium ions intercalating and deintercalating from lithium metal oxide into the negative electrode is repeated.
[0006] In an electrode assembly, multiple cell units are stacked, and within each cell unit, a negative electrode, a separator, and a positive electrode, typically cut to a predetermined size, are stacked in a predetermined order, or individual positive / separator / negative electrodes are repeatedly stacked to form an electrode assembly. Furthermore, the electrode assembly is housed in a casing such as a cylindrical can or a prismatic bag.
[0007] As a method for manufacturing electrode assemblies, the following electrode assemblies are known: a wound electrode assembly in which spacers are stacked between a negative electrode and a positive electrode, and then wound to manufacture the electrode assembly; a stacked electrode assembly in which each of the negative electrode and the positive electrode is cut to a desired width and length, and then the negative electrode, spacers, and positive electrode are repeatedly stacked to form the electrode assembly; and a stacked folded electrode assembly in which cell cells are placed parallel to each other on folded spacers, and then folded from one side to manufacture the electrode assembly.
[0008] The wound (jelly roll) electrode assembly is installed with the positive electrode 3, the separators 2 (2a and 2b) and the negative electrode 4 stacked on the core 1, and the core 1 is rotated to wind the positive electrode 3, the separators 2 and the negative electrode 4 around the core 1, thereby manufacturing the electrode assembly.
[0009] Here, as Figure 1b As shown, Figure 1b The diagram shows the unfolded state of the positive electrode 3 and the negative electrode 4. The electrode assembly has a structure in which, when winding is complete, the negative electrode 4 has uncoated portions 4a and 4c on the surface of the negative electrode current collector at its outermost end, on which no negative electrode active material is applied, and the negative electrode contact 4b is coupled to the uncoated portion 4a. Furthermore, the positive electrode 3 has an uncoated portion 3a on the surface of the positive electrode current collector at the middle of the longitudinal direction, on which no positive electrode active material is applied, such that when winding is complete, the positive electrode contact 3b is spaced apart from the negative electrode contact 4b by a predetermined distance, and the positive electrode contact 3b is coupled to the uncoated portion 3a.
[0010] In addition, such as Figure 1a As shown, Figure 1a The diagram shows a state in which two separators are first fixed to the core, and then the negative and positive electrodes are placed sequentially. First, separator 2 is placed in the core 1, and then the negative electrode 4 and positive electrode 3 are placed sequentially in the core 1. That is, in the method for manufacturing a jelly-roll type electrode assembly, the core 1 is rotated while the starting ends (the ends where winding begins) of the two separators 2a and 2b are fixed to the core 1 in an overlapping state, and then the negative electrode 4 is placed, and the positive electrode 3 is placed with a slight time difference. Alternatively, according to the manufacturing method, the negative electrode 4, the second separator, and the positive electrode 3 can be placed sequentially while the first separator 2a is wound around the core 1.
[0011] In addition, when the core 1 is rotated a predetermined number of revolutions with the positive electrode 3 inserted, the cylindrical electrode assembly is manufactured in a wound state in a stacked state in the order of separator / negative electrode / separator / positive electrode.
[0012] In the case of such cylindrical electrode assemblies, it is important to design the electrodes (negative and positive) to maximize performance and stability within a limited space.
[0013] Specifically, in the cylindrical electrode assembly, the positive electrode 3 and the negative electrode 4 have different contact area ratios due to the curvature from near the central hole (formed at the location where the core is removed) to the outside. Therefore, the N / P ratio (the capacity ratio of active material per unit area of the positive and negative electrodes) is unbalanced. The N / P ratio, which can be calculated using the following equation, varies depending on the contact area ratio between the positive and negative electrodes.
[0014] N / P ratio = Charging capacity per unit area of negative electrode (mHh / cm²) 2 ) × Negative electrode efficiency (%) / Design capacity per unit area of positive electrode (mHh / cm²) 2 )
[0015] That is, such as Figure 1c As shown, Figure 1c The diagram illustrates the states of region A near the central hole and outer region B in a cylindrical electrode assembly. When the overall capacity per unit area (capacity to hold electrons per unit area) of the positive electrode 3 is the same, the N / P ratio of region A near the central hole can be less than 100%, but the N / P ratio of outer region B can exceed 100%. Therefore, electrode degradation is accelerated in region A near the central hole, which has an adverse effect on the life of the secondary battery. Summary of the Invention
[0016] Technical issues
[0017] Therefore, the main objective of the present invention for solving the above problems is to provide an electrode assembly in which the positive electrode capacity in the region near the central hole and the positive electrode capacity in the outer region are different from each other, or the negative electrode capacity in the region near the central hole and the negative electrode capacity in the outer region are different from each other, so as to reduce the deviation of the N / P ratio.
[0018] Technical solution
[0019] To achieve the above objectives, the present invention provides an electrode assembly in which a positive electrode, a separator, and a negative electrode are wound in a stacked state, wherein the positive electrode includes a first positive electrode and a second positive electrode, each of the first positive electrode and the second positive electrode being manufactured by applying a positive electrode active material to the surface of a positive electrode current collector, wherein the positive electrode active material is not applied to one end to form an uncoated portion of the positive electrode exposing the positive electrode current collector thereon, and the uncoated portions of the first positive electrode and the second positive electrode are joined together to connect with each other.
[0020] The capacity per unit area of the first positive electrode and the capacity per unit area of the second positive electrode can be different from each other.
[0021] The positive electrode active material applied to the first positive electrode and the positive electrode active material applied to the second positive electrode can be manufactured by mixing the same components. However, the component ratio of the positive electrode active material applied to the first positive electrode and the component ratio of the positive electrode active material applied to the second positive electrode can be set differently based on atomic ratio or mass ratio, so that the capacity per unit area of the first positive electrode and the capacity per unit area of the second positive electrode are different from each other.
[0022] The amount of positive electrode active material applied to the first positive electrode and the amount of positive electrode active material applied to the second positive electrode can be the same.
[0023] In addition, the positive electrode active material applied to the first positive electrode and the positive electrode active material applied to the second positive electrode can be manufactured by mixing the same components, but the amount of positive electrode active material applied to the first positive electrode and the amount of positive electrode active material applied to the second positive electrode can be set differently, so that the capacity per unit area of the first positive electrode and the capacity per unit area of the second positive electrode are different from each other.
[0024] The amount of positive electrode active material applied to the first positive electrode and the amount of positive electrode active material applied to the second positive electrode can have the same composition ratio based on atomic ratio or mass ratio.
[0025] The positive electrode active material applied to the first positive electrode and the positive electrode active material applied to the second positive electrode can be manufactured by mixing the same components, but the amount of positive electrode active material applied to the first positive electrode and the component ratio of the positive electrode active material applied to the first positive electrode are set to be different from the amount of positive electrode active material applied to the second positive electrode and the component ratio of the positive electrode active material applied to the second positive electrode, so that the capacity per unit area of the first positive electrode and the capacity per unit area of the second positive electrode are different from each other.
[0026] In addition, the positive electrode contacts are overlapped and bonded to the uncoated portion of the first positive electrode and the uncoated portion of the second positive electrode at the points where they can bond to each other.
[0027] Here, one side of the positive electrode contact can be soldered to the uncoated portion of the first positive electrode, and the other side can be soldered to the uncoated portion of the second positive electrode.
[0028] The first positive electrode can be manufactured such that at least one of the amount of positive electrode active material applied to one surface of the positive electrode current collector or the composition ratio based on the atomic ratio or mass ratio of the positive electrode active material is different from at least one of the amount of positive electrode active material applied to the other surface of the positive electrode current collector or the composition ratio based on the atomic ratio or mass ratio of the positive electrode active material, such that the capacity per unit area on one surface and the capacity per unit area on the other surface are different from each other.
[0029] The second positive electrode can be manufactured such that at least one of the amount of positive electrode active material applied to one surface of the positive electrode current collector or the composition ratio based on the atomic ratio or mass ratio of the positive electrode active material is different from at least one of the amount of positive electrode active material applied to the other surface of the positive electrode current collector or the composition ratio based on the atomic ratio or mass ratio of the positive electrode active material, such that the capacity per unit area on one surface and the capacity per unit area on the other surface are different from each other.
[0030] Furthermore, the present invention also provides a structure with a segmented positive electrode and a structure with a segmented negative electrode as described above. That is, according to the present invention having the above-described technical features, in an electrode assembly in which the positive electrode, separator, and negative electrode are wound in a stacked state, the negative electrode includes a first negative electrode and a second negative electrode. Each of the first negative electrode and the second negative electrode is manufactured by applying a negative electrode active material to the surface of a negative electrode current collector, wherein the negative electrode active material is not applied to one end to form an uncoated negative electrode portion thereon that exposes the negative electrode current collector, and the uncoated negative electrode portions of the first negative electrode and the second negative electrode are joined together to connect with each other.
[0031] The negative electrode active material applied to the first negative electrode and the negative electrode active material applied to the second negative electrode can be manufactured by mixing the same components, but the component ratio of the negative electrode active material applied to the first negative electrode and the component ratio of the negative electrode active material applied to the second negative electrode can be set differently based on atomic ratio or mass ratio.
[0032] The amount of negative electrode active material applied to the first negative electrode and the amount of negative electrode active material applied to the second negative electrode can be the same.
[0033] Alternatively, the negative electrode active material applied to the first negative electrode and the negative electrode active material applied to the second negative electrode can be manufactured by mixing the same components, but the amounts of the negative electrode active material applied to the first negative electrode and the amounts of the negative electrode active material applied to the second negative electrode are set differently.
[0034] The negative electrode contacts can be overlapped and joined to the point where the uncoated portions of the first negative electrode and the uncoated portions of the second negative electrode meet each other.
[0035] One side of the negative electrode contact can be soldered to the uncoated portion of the first negative electrode, and the other side can be soldered to the uncoated portion of the second negative electrode.
[0036] Alternatively, at the end opposite to the side connected to the second negative electrode, an uncoated portion of the negative electrode is additionally formed on the first negative electrode, and at the end opposite to the side connected to the first negative electrode, an uncoated portion of the negative electrode is additionally formed on the second negative electrode (similar to that according to the related art). Figure 1b(as shown in the structure), wherein the negative electrode contact is bonded to either the uncoated portion of the negative electrode additionally formed on the first negative electrode or the uncoated portion of the negative electrode additionally formed on the second negative electrode.
[0037] Additionally, a secondary battery in which an electrode assembly having the above-mentioned technical features is embedded in the casing can be provided as an additional accessory.
[0038] Beneficial effects
[0039] In the electrode assembly with the above configuration according to the present invention, since the positive electrode has a structure in which the first positive electrode and the second positive electrode are joined together, the first positive electrode and the second positive electrode can be manufactured separately, thereby determining the capacity per unit area according to whether the first positive electrode and the second positive electrode are disposed on the central side or the outer side, so as to reduce the deviation of the N / P ratio compared with the structure according to the related art.
[0040] Here, the capacity per unit area of the first positive electrode and the second positive electrode can be different from each other, and the first positive electrode and the second positive electrode have different thicknesses. In addition, since the capacity per unit area of one surface and the other surface can also be different from each other, the capacity per unit area can be adjusted according to the winding position.
[0041] Furthermore, since the positive electrode contacts overlap and are bonded to the points where the uncoated portions of the first and second positive electrodes meet, the bonding force between the first and second positive electrodes can be increased.
[0042] Furthermore, since the technical features applied to the positive electrode as described above can also be applied to the negative electrode, it is possible to flexibly determine whether to apply the technical features to the positive or negative electrode based on the manufacturing conditions. Attached Figure Description
[0043] Figure 1a This is a view showing the state in which two separators are first fixed to the core and then the negative and positive electrodes are placed in sequence.
[0044] Figure 1b This shows the expansion based on related technologies, such as Figure 1a A view showing the state of the positive and negative electrodes as indicated.
[0045] Figure 1c This is a view showing the state of region A near the central hole and outer region B in which a cylindrical electrode assembly is set.
[0046] Figure 2 It is a view showing the state in which the positive and negative electrodes are deployed, wherein the positive electrodes are configured such that the first positive electrode and the second positive electrode are engaged with each other.
[0047] Figure 3It is a view showing the state in which, after the first positive electrode and the second positive electrode are joined together, the positive electrode tab is additionally joined to the point where the first positive electrode and the second positive electrode are joined together.
[0048] Figure 4 The following are cross-sectional views: (a) showing the state in which positive electrode active materials with the same composition ratio are applied to two surfaces of the first and second positive electrodes; (b) showing the state in which positive electrode active materials with different composition ratios are applied to one surface and the other surface, respectively; and (c) showing the state in which positive electrode active materials with the same composition ratio are applied to two side surfaces in different amounts.
[0049] Figure 5 This is a view showing the state (d) before the first and second positive electrodes, to which positive electrode active materials with different component ratios are applied respectively, are bonded together, and the state (e) before the first and second positive electrodes, to which positive electrode active materials with the same component ratio are applied in different amounts, are bonded together.
[0050] Figure 6 It is a view showing the state in which the positive and negative electrodes are deployed, wherein the negative electrodes are configured such that the first negative electrode and the second negative electrode are engaged with each other.
[0051] Figure 7 This is a view showing the state in which, after the first negative electrode and the second negative electrode are joined together, the negative electrode contact is additionally joined to the point where the first negative electrode and the second negative electrode are joined together. Detailed Implementation
[0052] In the following, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can readily implement the technical concept of the present invention. However, the present invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein.
[0053] For the sake of clarity in describing the invention, parts that are not relevant to the description have been omitted, and throughout the specification, the same reference numerals are assigned to the same or similar parts.
[0054] Furthermore, the terms or words used in this specification and claims should not be construed as having a general meaning or a dictionary-based meaning, but should be interpreted as meanings and concepts that are within the scope of this invention, based on the principle that the inventor can appropriately define the concepts of the terms in order to best describe and illustrate his or her invention.
[0055] This invention relates to an electrode assembly in which a first positive electrode 10 and a second positive electrode 20 have different capacities per unit area to suppress or at least mitigate the problem of N / P ratio deviation between the region near the central hole and the outer region, and to an electrode assembly in which a first negative electrode 40 and a second negative electrode 50 are joined to form a negative electrode 200. The invention will be described in more detail below with reference to the accompanying drawings.
[0056] Electrode assembly used in the positive electrode
[0057] Figure 2 This is a view showing the state in which the positive electrode 100 and the negative electrode 200 are deployed, wherein the positive electrode 100 is configured such that the first positive electrode 10 and the second positive electrode 20 are engaged with each other, and Figure 3 This is a view showing the state in which, after the first positive electrode 10 and the second positive electrode 20 are joined to each other, the positive electrode contact 30 is additionally joined to the point where the first positive electrode 10 and the second positive electrode 20 are joined to each other.
[0058] Reference Figure 2 and Figure 3 The electrode assembly of the present invention is manufactured by winding a spacer, a negative electrode 200, a spacer, and a positive electrode 100 in a stacked state. When the starting ends of the two spacers are wound around the core, the negative electrode 200 and the positive electrode 100 are placed in sequence to manufacture the electrode assembly.
[0059] Here, in the electrode assembly according to the invention, the positive electrode 100 is configured such that a first positive electrode 10 and a second positive electrode 20 with different capacities per unit area are joined to each other.
[0060] That is, the first positive electrode 10 is manufactured by applying a positive electrode active material to the surface of the positive electrode current collector, and the second positive electrode 20 is also manufactured by applying a positive electrode active material to the surface of the positive electrode current collector.
[0061] In addition, each of the first positive electrode 10 and the second positive electrode 20 has a structure in which uncoated portions 11 and 21 of the positive electrode, on which no positive active material is applied to expose the positive current collector, are formed on the ends of the first positive electrode 10 and the second positive electrode 20, and the uncoated portions 11 of the first positive electrode 10 and the uncoated portions 21 of the second positive electrode 20 are joined to each other by welding or conductive adhesive.
[0062] Furthermore, the positive electrode contacts 30 are overlapped and bonded to the points where the uncoated positive electrode portion 11 of the first positive electrode 10 and the uncoated positive electrode portion 21 of the second positive electrode 20 meet. More specifically, the positive electrode contacts 30 are bonded such that one side is soldered to the uncoated positive electrode portion 11 of the first positive electrode 10, and the other side is soldered to the uncoated positive electrode portion 21 of the second positive electrode 20. Therefore, the positive electrode contacts 30 allow for increased bonding strength between the first positive electrode 10 and the second positive electrode 20.
[0063] Figure 4 The cross-sectional view (a) shows the state in which positive electrode active materials with the same composition ratio are applied to two surfaces of the first positive electrode 10 and the second positive electrode 20, the cross-sectional view (b) shows the state in which positive electrode active materials with different composition ratios are applied to one surface and the other surface, respectively, and the cross-sectional view (c) shows the state in which positive electrode active materials with the same composition ratio are applied to the two surfaces in different amounts.
[0064] like Figure 4 As shown in (a), a first positive electrode 10 and a second positive electrode 20 can be applied such that the positive electrode active material A1 with the same composition ratio has the same thickness on one side and the other side of the positive electrode current collector C.
[0065] In addition, such as Figure 4 As shown in (b), by increasing or decreasing the content of a specific component related to stability or capacity to a different ratio than that of the positive electrode active material A1 applied to one surface, the positive electrode active material A2 can be applied to another surface of the positive electrode current collector C, such that the capacity per unit area of the two surfaces is different from that of each other.
[0066] Alternative locations, such as Figure 4 As shown in (c), positive electrode active materials A1 and A3 with the same composition ratio can be applied to two surfaces, but the capacity per unit area can differ from one another because the amount of positive electrode active material on the other surface is greater than the amount of positive electrode active material applied to one surface.
[0067] That is, in this invention, all of the first positive electrode 10 and the second positive electrode 20, or any one of the first positive electrode 10 and the second positive electrode 20, can be manufactured such that at least one of the amount of positive electrode active material A1 applied to one surface of the positive electrode current collector C, or the composition ratio based on the atomic ratio or mass ratio of positive electrode active material A1, is different from at least one of the amount of each of positive electrode active materials A2 and A3 applied to the other surface of the positive electrode current collector C, or the composition ratio based on the atomic ratio or mass ratio of each of positive electrode active materials A2 and A3. Therefore, the capacity per unit area on one surface and the capacity per unit area on the other surface can be different from each other.
[0068] Therefore, the present invention provides an embodiment in which the capacity per unit area of the first positive electrode 10 and the second positive electrode 20 are formed differently by combining the above-described features.
[0069] First Implementation Method
[0070] Figure 5 This is a view showing the state (d) before the first positive electrode 10 and the second positive electrode 20, on which positive electrode active materials with different component ratios are applied respectively, are bonded together, and the state (e) before the first positive electrode 10 and the second positive electrode 20, on which positive electrode active materials with the same component ratio are applied in different amounts, are bonded together.
[0071] In this embodiment, the positive electrode active material A1 applied to the first positive electrode 10 and the positive electrode active material A2 applied to the second positive electrode 20 are manufactured by mixing the same components. However, based on the atomic ratio or mass ratio, the component ratio of the positive electrode active material A1 applied to the first positive electrode 10 and the component ratio of the positive electrode active material A2 applied to the second positive electrode 20 are set to be different from each other. Therefore, the capacity per unit area of the first positive electrode 10 and the capacity per unit area of the second positive electrode 20 can be different from each other.
[0072] That is, such as Figure 5 As shown in (d), the composition ratio of the positive electrode active material applied to the positive electrode current collector C can be changed, and therefore, the capacity per unit area of the first positive electrode 10 and the second positive electrode 20 can be different from each other.
[0073] Here, the positive electrode active material A1 applied to the first positive electrode 10 and the positive electrode active material A2 applied to the second positive electrode 20 can be applied in the same amount (and can have the same thickness).
[0074] Second Implementation Method
[0075] In addition, such as Figure 5 As shown in (e), the positive electrode active material A1 applied to the first positive electrode 10 and the positive electrode active material A3 applied to the second positive electrode 20 are manufactured by mixing the same components, but the amount of positive electrode active material A1 applied to the first positive electrode 10 and the amount of positive electrode active material A3 applied to the second positive electrode 20 are set to be different from each other, and therefore, the capacity per unit area of the first positive electrode 10 and the capacity per unit area of the second positive electrode 20 can be different from each other.
[0076] Here, the positive electrode active material A1 applied to the first positive electrode 10 and the positive electrode active material A2 applied to the second positive electrode 20 can be manufactured to have the same composition ratio based on atomic ratio or mass ratio.
[0077] Alternatively, the positive electrode active material applied to the first positive electrode 10 and the positive electrode active material applied to the second positive electrode 20 are manufactured by mixing the same components according to a combination of the first and second embodiments. However, the amount of positive electrode active material applied to the first positive electrode and the component ratio based on the atomic ratio or mass ratio of the positive electrode active material can be set differently from the amount of positive electrode active material applied to the second positive electrode 20 and the component ratio based on the atomic ratio or mass ratio of the positive electrode active material. Therefore, the capacity per unit area of the first positive electrode 10 and the capacity per unit area of the second positive electrode 20 can be different from each other.
[0078] Furthermore, although only the connection structure of the first positive electrode 10 and the second positive electrode 20 with different capacities per unit area is described in this invention, an uncoated portion 21 can be additionally formed at the opposite end of the second positive electrode 20, and then a third positive electrode and a fourth positive electrode can be connected in sequence, each of the third and fourth positive electrodes having an uncoated portion. In this case, the capacity per unit area of each of the additionally connected third and fourth electrodes can be different from the capacity per unit area of each of the first and second electrodes.
[0079] Electrode assembly used for the negative electrode
[0080] As described above, in the electrode assembly according to the present invention, the configuration applied to the positive electrode can also be applied to the negative electrode.
[0081] Figure 6 This is a view showing the unfolded positive and negative electrodes, wherein the negative electrode 200 is configured such that the first negative electrode 40 and the second negative electrode 50 are engaged with each other, and Figure 7 This is a view showing the state in which, after the first negative electrode 40 and the second negative electrode 50 are joined together, the negative electrode tab is additionally joined to the point where the first negative electrode 40 and the second negative electrode 50 are joined together.
[0082] Reference Figure 6 and Figure 7 The electrode assembly according to the invention, having a structure in which two negative electrodes are connected to each other, is manufactured by winding a spacer, a negative electrode 200, a spacer, and a positive electrode 100 in a stacked state. The negative electrode 200 and the positive electrode 100 are placed sequentially when the starting ends of the two spacers are wound around the core to manufacture the electrode assembly.
[0083] Here, in the electrode assembly according to the invention, the negative electrode 200 is configured such that the first negative electrode 40 and the second negative electrode 50, which have different capacities per unit area, are joined to each other.
[0084] That is, similar to the structure of the positive electrode described above, the first negative electrode 40 is manufactured by applying a negative electrode active material to the surface of the negative electrode current collector, and the second negative electrode 50 is also manufactured by applying a negative electrode active material to the surface of the negative electrode current collector.
[0085] In addition, each of the first negative electrode 40 and the second negative electrode 50 has a structure in which uncoated portions 41 and 41 of the negative electrode, on which no negative electrode active material is applied to expose the negative electrode current collector, are formed on the ends of the first negative electrode 40 and the second negative electrode 50, and the uncoated portions 41 of the first negative electrode 40 and the uncoated portions 51 of the second negative electrode 50 are joined together by welding or conductive adhesive.
[0086] Furthermore, the negative electrode contact 60 is overlapped and joined to the point where the uncoated negative electrode portion 41 of the first negative electrode 40 and the uncoated negative electrode portion 51 of the second negative electrode 50 meet. More specifically, the negative electrode contact 60 is joined such that one side of it is soldered to the uncoated negative electrode portion 41 of the first negative electrode 40, and the other side of it is soldered to the uncoated negative electrode portion 51 of the second negative electrode 50. Therefore, the negative electrode contact 60 allows for increased bonding strength between the first negative electrode 40 and the second negative electrode 50.
[0087] For reference, and based on the structure of the relevant technology ( Figure 1b Similar to the structure shown, the negative electrode contact 60 can be attached to one end of the negative electrode. That is, an uncoated negative electrode portion 42 can be additionally formed on the first negative electrode 40 at the end opposite to the side connected to the second negative electrode 50, and an uncoated negative electrode portion 52 can be additionally formed on the second negative electrode 50 at the end opposite to the side connected to the first negative electrode 40. Alternatively, the electrode assembly can have a structure in which the negative electrode contact 60 is attached to either the uncoated negative electrode portion 42 additionally formed on the first negative electrode 40 or the uncoated negative electrode portion 52 additionally formed on the second negative electrode 50.
[0088] Furthermore, similar to the structure of the positive electrode described above, each of the first negative electrode 40 and the second negative electrode 50 may have a structure in which negative electrode active materials with the same composition ratio are applied to one side and the other side of the negative electrode current collector with the same thickness.
[0089] Alternatively, a negative electrode active material composed of different component ratios can be applied to another surface of the negative electrode current collector by increasing or decreasing the content of specific components related to stability or capacity, which is different from the component ratio of the negative electrode active material applied to one surface, so that the capacity per unit area of the two surfaces is different from each other.
[0090] Alternatively, negative electrode active materials with the same composition ratio can be applied to both surfaces of the negative electrode current collector, but the capacity per unit area can differ from one another because the amount of negative electrode active material on the other surface is greater than the amount of negative electrode active material applied to one surface.
[0091] That is, all of the first negative electrode 40 and the second negative electrode 50, or any one of the first negative electrode 40 and the second negative electrode 50, can be manufactured such that at least one of the amount of negative electrode active material applied to one surface of the negative electrode current collector, or the composition ratio based on the atomic ratio or mass ratio of the negative electrode active material, is different from at least one of the amount of each of the negative electrode active materials applied to the other surface of the negative electrode current collector, or the composition ratio based on the atomic ratio or mass ratio of the negative electrode active material. Therefore, the capacity per unit area on one surface and the capacity per unit area on the other surface can be different from each other.
[0092] Therefore, in this invention, the capacity per unit area of the first negative electrode 40 and the second negative electrode 50 can be formed in a manner different from that in the configuration formed by combining the above-described features, where the capacity per unit area of the first positive electrode 10 and the second positive electrode 20 is formed differently.
[0093] Furthermore, it is also possible to additionally form an uncoated portion of the negative electrode at the opposite end of the second negative electrode 50, and to sequentially connect the third and fourth negative electrodes, each of which has an uncoated portion. Here, each of the additionally connected third and fourth negative electrodes may also have a different capacity than each of the first and second negative electrodes.
[0094] In the electrode assembly with the above configuration according to the present invention, since the positive electrode 100 has a structure in which the first positive electrode 10 and the second positive electrode 20 are joined together, or the negative electrode 200 has a structure in which the first negative electrode 40 and the second negative electrode 50 are joined together, each of the positive electrode 100 and the negative electrode 200 can be determined according to whether the first positive electrode and the second positive electrode or the first negative electrode and the second negative electrode are disposed on the central side or the outer side, so as to reduce the deviation of the N / P ratio.
[0095] Here, the capacity per unit area of the first positive electrode 10 and the second positive electrode 20, or the first negative electrode 40 and the second negative electrode 50, can be different from each other, and the first positive electrode and the second positive electrode, or the first negative electrode 40 and the second negative electrode 50, have different thicknesses. Furthermore, since the capacity per unit area of one surface and another surface can also be different from each other, the capacity per unit area can be adjusted according to the winding position.
[0096] Furthermore, since the positive electrode contact 30 can be overlapped and connected to the point where the uncoated positive electrode portion 21 of the first positive electrode 10 and the uncoated positive electrode portion 21 of the second positive electrode 20 are joined together, or the negative electrode contact 60 can be overlapped and connected to the point where the uncoated negative electrode portion 41 of the first negative electrode 40 and the uncoated negative electrode portion 51 of the second negative electrode 50 are joined together, the bonding force between the first positive electrode and the second positive electrode or the bonding force between the first negative electrode and the second negative electrode can be increased.
[0097] In addition, in this invention, a secondary battery in which the electrode assembly described above is embedded in the housing can be provided.
[0098] Although embodiments of the invention have been described with reference to specific examples, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
[0099] [Description of reference numerals in the attached figures]
[0100] 10: First positive electrode
[0101] 20: Second positive electrode
[0102] 30: Positive electrode connector
[0103] 40: First negative electrode
[0104] 50: Second negative electrode
[0105] 60: Negative electrode connector
[0106] 100: Positive electrode
[0107] 200: Negative electrode
Claims
1. An electrode assembly in which a positive electrode, a spacer, and a negative electrode are wound in a stacked state. in, The positive electrode includes a first positive electrode and a second positive electrode. Each of the first and second positive electrodes is manufactured by applying a positive electrode active material to the surface of a positive electrode current collector, wherein the positive electrode active material is not applied to one end to form an uncoated portion thereon exposing the positive electrode current collector, and the uncoated portions of the first and second positive electrodes are bonded together to connect with each other. The capacity per unit area of the first positive electrode and the capacity per unit area of the second positive electrode are different from each other.
2. The electrode assembly according to claim 1, wherein, The positive electrode active material applied to the first positive electrode and the positive electrode active material applied to the second positive electrode are manufactured by mixing the same components, but the component ratio of the positive electrode active material applied to the first positive electrode and the component ratio of the positive electrode active material applied to the second positive electrode are set differently based on atomic ratio or mass ratio, such that the capacity per unit area of the first positive electrode and the capacity per unit area of the second positive electrode are different from each other.
3. The electrode assembly according to claim 2, wherein, The amount of positive electrode active material applied to the first positive electrode is the same as the amount of positive electrode active material applied to the second positive electrode.
4. The electrode assembly according to claim 1, wherein, The positive electrode active material applied to the first positive electrode and the positive electrode active material applied to the second positive electrode are manufactured by mixing the same components, but the amounts of the positive electrode active material applied to the first positive electrode and the positive electrode active material applied to the second positive electrode are set differently, such that the capacity per unit area of the first positive electrode and the capacity per unit area of the second positive electrode are different from each other.
5. The electrode assembly according to claim 4, wherein, The amount of positive electrode active material applied to the first positive electrode and the amount of positive electrode active material applied to the second positive electrode have the same composition ratio based on atomic ratio or mass ratio.
6. The electrode assembly according to claim 1, wherein, The positive electrode active material applied to the first positive electrode and the positive electrode active material applied to the second positive electrode are manufactured by mixing the same components, but the amount of positive electrode active material applied to the first positive electrode and the component ratio of the positive electrode active material applied to the first positive electrode are set to be different from the amount of positive electrode active material applied to the second positive electrode and the component ratio of the positive electrode active material applied to the second positive electrode, such that the capacity per unit area of the first positive electrode and the capacity per unit area of the second positive electrode are different from each other.
7. The electrode assembly according to claim 1, wherein, The positive electrode contacts are overlapped and bonded to the points where the uncoated portions of the first positive electrode and the uncoated portions of the second positive electrode are joined together.
8. The electrode assembly according to claim 7, wherein, One side of the positive electrode contact is soldered to the uncoated portion of the first positive electrode, and the other side is soldered to the uncoated portion of the second positive electrode.
9. The electrode assembly according to claim 1, wherein, The first positive electrode is manufactured such that at least one of the amount of positive electrode active material applied to one surface of the positive electrode current collector or the composition ratio based on the atomic ratio or mass ratio of the positive electrode active material is different from at least one of the amount of positive electrode active material applied to the other surface of the positive electrode current collector or the composition ratio based on the atomic ratio or mass ratio of the positive electrode active material, such that the capacity per unit area on the one surface and the capacity per unit area on the other surface are different from each other.
10. The electrode assembly according to claim 1, wherein, The second positive electrode is manufactured such that at least one of the amount of positive electrode active material applied to one surface of the positive electrode current collector or the composition ratio based on the atomic ratio or mass ratio of the positive electrode active material is different from at least one of the amount of positive electrode active material applied to the other surface of the positive electrode current collector or the composition ratio based on the atomic ratio or mass ratio of the positive electrode active material, such that the capacity per unit area on the one surface and the capacity per unit area on the other surface are different from each other.
11. An electrode assembly in which a positive electrode, a spacer, and a negative electrode are wound in a stacked state. in, The negative electrode includes a first negative electrode and a second negative electrode. Each of the first and second negative electrodes is manufactured by applying a negative electrode active material to the surface of a negative electrode current collector, wherein the negative electrode active material is not applied to one end to form an uncoated negative electrode portion thereon that exposes the negative electrode current collector. The uncoated portions of the first and second negative electrodes are joined together to connect with each other, and The capacity per unit area of the first negative electrode and the capacity per unit area of the second negative electrode are different from each other.
12. The electrode assembly according to claim 11, wherein, The negative electrode active material applied to the first negative electrode and the negative electrode active material applied to the second negative electrode are manufactured by mixing the same components, but the component ratio of the negative electrode active material applied to the first negative electrode and the component ratio of the negative electrode active material applied to the second negative electrode are set differently based on atomic ratio or mass ratio.
13. The electrode assembly according to claim 11, wherein, The amount of negative electrode active material applied to the first negative electrode is the same as the amount of negative electrode active material applied to the second negative electrode.
14. The electrode assembly according to claim 11, wherein, The negative electrode active material applied to the first negative electrode and the negative electrode active material applied to the second negative electrode are manufactured by mixing the same components, but the amounts of the negative electrode active material applied to the first negative electrode and the amounts of the negative electrode active material applied to the second negative electrode are set differently.
15. The electrode assembly according to claim 11, wherein, The negative electrode contacts are overlapped and joined to the point where the uncoated portions of the first negative electrode and the uncoated portions of the second negative electrode meet each other.
16. The electrode assembly according to claim 15, wherein, One side of the negative electrode contact is soldered to the uncoated portion of the first negative electrode, and the other side is soldered to the uncoated portion of the second negative electrode.
17. The electrode assembly of claim 11, wherein, At the end opposite to the side connected to the second negative electrode, an uncoated portion of the negative electrode is additionally formed on the first negative electrode, and at the end opposite to the side connected to the first negative electrode, an uncoated portion of the negative electrode is additionally formed on the second negative electrode. The negative electrode contact is bonded to either the uncoated portion of the negative electrode additionally formed on the first negative electrode or the uncoated portion of the negative electrode additionally formed on the second negative electrode.
18. A secondary battery in which the electrode assembly of any one of claims 1 to 17 is embedded in a housing.