Electrical cells and batteries containing them

Abstract

To provide an electric cell with a stable structure which can significantly improve the stability of a battery.SOLUTION: The electric cell is a winding body formed by winding a laminate body including a positive electrode sheet 160, a negative electrode sheet 120, a separator 140, positive electrode tabs 170a and 170b, and negative electrode tabs 130a, 130b, and 130c. A negative electrode coating 122 is not formed for a predetermined length from a winding start end A1 in the surface of the negative electrode sheet. The ratio of the predetermined length to the length of the negative electrode sheet is in the range from 0.015 to 0.100.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] [Background of the Invention] [Technical Field] This application is a priority application based on Article 119 of the United States Patent Law for Taiwan Patent Application No. 112117721 filed on May 12, 2023 and Taiwan Patent Application No. 112204699 filed on May 12, 2023, and the entire contents of these documents are incorporated herein by reference.

[0002] The present invention relates to an electric cell and a battery including the same, and more particularly to an electric cell capable of preventing structural deformation due to thermal stress at high temperatures during charging and discharging, and a battery including the same.

Background Art

[0003] Electronics products being developed for the future tend to gradually increase in capacity and voltage, and the specification requirements for lithium batteries as power sources are also becoming increasingly high. On the other hand, as the capacity of the electric cells in the battery increases, the safety requirements also increase.

[0004] In the conventional technology, during the charging and discharging of the battery, the electrolyte undergoes a decomposition oxidation reaction, generating a large amount of heat. If this thermal energy is not suppressed in a timely manner, the accumulated thermal energy will cause a further temperature increase. When the temperature reaches a certain level, certain thermal stresses are generated, causing the positive electrode sheet and the negative electrode sheet of the battery to deform. Due to this deformation, the electrode coating formed by the electrode slurry in the battery may peel off, significantly reducing the output efficiency of the battery or causing defects and the battery to malfunction. Furthermore, if the charging and discharging of such defective batteries continues, the structure becomes unstable, and there is also a risk of explosion and ignition. Therefore, how to suppress the deformation of the battery due to high-temperature thermal stress is a major issue to be solved in the current lithium battery-related industries.

[0005] In addition to the above challenges, the current method for manufacturing lithium batteries is as follows: First, a positive electrode sheet, a negative electrode sheet, and a separator are stacked, and the stacked material is wound around a cylindrical body (e.g., an iron rod) as a winding support to form an electrical cell. This electrical cell is then placed in a battery case, the positive and negative electrodes are electrically connected, and finally a lithium battery is formed. However, the cylindrical body occupies a certain amount of space and weight within the battery, making it difficult to develop batteries in line with the trend towards lighter and more compact designs. Therefore, how to reduce the weight and space of the battery without affecting its performance (e.g., electrical capacity) is one of the challenges that needs to be addressed in the current lithium battery industry. [Overview of the project]

[0006] In view of the above, the object of the present invention is to provide a battery that solves the above problems.

[0007] To achieve the above objective, the present invention provides an electrical cell which is a wound body formed by winding a laminate. The laminate comprises: a positive electrode sheet which is a positive electrode substrate having a positive electrode upper surface and a positive electrode lower surface opposite to the positive electrode upper surface, wherein at least one of the positive electrode upper surface and the positive electrode lower surface has a positive electrode coating; a negative electrode sheet which is a negative electrode substrate having a negative electrode upper surface and a negative electrode lower surface opposite to the negative electrode upper surface, wherein at least one of the negative electrode upper surface and the negative electrode lower surface has a negative electrode coating, and at least one of the negative electrode upper surface and the negative electrode lower surface does not have a negative electrode coating from the winding start end of the negative electrode sheet to a predetermined length, and the ratio of the predetermined length to the length of the negative electrode sheet is in the range of 0.015 to 0.100; a separator disposed between the positive electrode sheet and the negative electrode sheet; a positive electrode tab connected to the positive electrode upper surface or the positive electrode lower surface; and a negative electrode tab connected to the negative electrode upper surface or the negative electrode lower surface.

[0008] Preferably, at least one of the upper and lower surfaces of the negative electrode is not provided with a support member from the winding start end to a predetermined length. More preferably, neither the upper nor lower surface of the negative electrode is provided with a support member from the winding start end to a predetermined length.

[0009] Preferably, the ratio of the predetermined length to the length of the negative electrode sheet is in the range of 0.017 to 0.093.

[0010] Preferably, neither the upper nor lower surface of the negative electrode has a negative electrode coating between the winding start end and a predetermined length.

[0011] Preferably, the positive electrode tab comprises a first positive electrode tab and a second positive electrode tab, both of which are connected to the positive electrode upper surface.

[0012] Preferably, the negative electrode tab includes a first negative electrode tab, a second negative electrode tab, and a third negative electrode tab, all of which are connected to the upper surface of the negative electrode.

[0013] Furthermore, the present invention provides a battery comprising: a housing comprising: a lid; a can; and a housing space formed by the lid and the can being sealed and joined together; a positive electrode terminal embedded in the lid; a negative electrode terminal embedded in the can; and the aforementioned electrical cell, which is located within the housing space and connected to the positive electrode terminal via a positive electrode tab and to the negative electrode terminal via a negative electrode tab.

[0014] Preferably, the battery further comprises an electrolyte arranged within a housing space.

[0015] The present invention increases the proportion of the empty foil region at the winding start end of the negative electrode sheet (i.e., the region not covered by the negative electrode film formed by the negative electrode slurry) in the negative electrode sheet, thereby mitigating the occurrence of thermal stress concentration in the internal coil of the electrical cell, and preventing the peeling of the electrode film formed by the electrode slurry on the negative electrode sheet and positive electrode sheet, and ultimately preventing battery failure. [Brief explanation of the drawing]

[0016] [Figure 1] Figure 1 is a side view showing the laminate of an electric cell 100 before winding, according to one embodiment of the present invention.

[0017] [Figure 2] FIG. 2 is an X-ray computed tomography image of cross-sections taken along a plurality of different cross-section lines I-I of an electric cell according to an embodiment of the present invention.

[0018] [Figure 3] FIG. 3 is an X-ray computed tomography image of cross-sections taken along a plurality of different cross-section lines I-I of an electric cell of a comparative example.

[0019] [Figure 4] FIG. 4 is a diagram showing analysis results of values of the central temperature of individual electric cells where (a) a predetermined length D in the electric cell is 16 mm; (b) the predetermined length D in the electric cell is 25 mm; and (c) the predetermined length D in the electric cell is 35 mm.

[0020] [Figure 5] FIG. 5 is a schematic diagram of a battery according to the present invention.

Embodiments for Carrying Out the Invention

[0021] The present invention provides an electric cell which is a wound body formed by winding a laminate. The laminate includes a positive electrode sheet which is a positive electrode substrate having a positive electrode upper surface and a positive electrode lower surface on the opposite side of the positive electrode upper surface, and at least one of the positive electrode upper surface and the positive electrode lower surface has a positive electrode coating; a negative electrode sheet which is a negative electrode substrate having a negative electrode upper surface and a negative electrode lower surface on the opposite side of the negative electrode upper surface, at least one of the negative electrode upper surface and the negative electrode lower surface has a negative electrode coating, and at least one of the negative electrode upper surface and the negative electrode lower surface does not have a negative electrode coating from the winding start end of the negative electrode sheet to a predetermined length, and the ratio of the predetermined length to the length of the negative electrode sheet is in the range of 0.015 to 0.100; a separator disposed between the positive electrode sheet and the negative electrode sheet; a positive electrode tab connected to the positive electrode upper surface or the positive electrode lower surface; and a negative electrode tab connected to the negative electrode upper surface or the negative electrode lower surface.

[0022] The electric cell of the present invention can suppress deformation due to thermal stress at high temperatures, enhance the stability of the battery, and is extremely suitable as a battery. Therefore, the present invention further provides a battery. The battery includes a housing including a lid body, a can, and a housing space formed by sealing and joining the lid body and the can to each other; a positive electrode terminal embedded in the lid body; a negative electrode terminal embedded in the can; and the above-described electric cell disposed in the housing space, connected to the positive electrode terminal via a positive electrode tab, and connected to the negative electrode terminal via a negative electrode tab.

[0023] Preferred embodiments are shown below as examples for explaining the present invention, but these embodiments should not be construed as limiting the scope of legal protection of the present invention.

[0024] FIG. 1 shows a side view of a laminate before winding of an electric cell 100 according to an embodiment of the present invention. In the present embodiment, the laminate includes a positive electrode sheet 160, a negative electrode sheet 120, a separator 140, a plurality of positive electrode tabs 170, and a plurality of negative electrode tabs 130. The separator 140 is disposed between the positive electrode sheet 160 and the negative electrode sheet 120, that is, the positive electrode sheet 160 and the negative electrode sheet 120 face each other with the separator 140 interposed therebetween.

[0025] The positive electrode sheet 160 is a positive electrode substrate 161. The positive electrode substrate 161 has a positive electrode upper surface 160a and a positive electrode lower surface 160b on the opposite side of the positive electrode upper surface 160a, and at least one of the positive electrode upper surface 160a and the positive electrode lower surface 160b has a positive electrode coating 162. In the present embodiment, both the positive electrode upper surface 160a and the positive electrode lower surface 160b have a positive electrode coating 162 formed thereon, and the positive electrode coating 162 is formed by a positive electrode slurry.

[0026] In the present invention, the negative electrode sheet 120 is a negative electrode substrate 121. The negative electrode substrate 121 has a negative electrode upper surface 120a and a negative electrode lower surface 120b opposite to the negative electrode upper surface 120a, and at least one of the negative electrode upper surface 120a and the negative electrode lower surface 120b has a negative electrode coating 122. In this embodiment, both the negative electrode upper surface 120a and the negative electrode lower surface 120b have a negative electrode coating 122 formed thereon, and the negative electrode coating 122 is formed by a negative electrode slurry.

[0027] At least one of the negative electrode upper surface 120a and the negative electrode lower surface 120b is not covered with a negative electrode coating from the winding start end A1 to a predetermined length D. In this embodiment, the negative electrode coating is not provided on either the negative electrode upper surface 120a or the negative electrode lower surface 120b between the winding start end A1 of the negative electrode sheet and the predetermined length D from the winding start end A1. That is, on the negative electrode upper surface 120a and the negative electrode lower surface 120b, there is a strip-shaped region that is not covered with a negative electrode coating (because the negative electrode sheet is rectangular) from the winding start end A1 to the predetermined length D. More specifically, the lengths of both sides of the strip-shaped zone not covered by the negative electrode coating correspond to the lengths of the sides of the winding start end, and the lengths of the other two sides are both D. In the present invention, the ratio of a predetermined length D to the length of the negative electrode sheet is preferably in the range of 0.015 to 0.100, for example, 0.017, 0.024, 0.045, 0.055, 0.065, 0.070, 0.085, or 0.095. More preferably, the ratio of a predetermined length D to the length of the negative electrode sheet is in the range of 0.017 to 0.093, for example, 0.022 to 0.090, or 0.023 to 0.070, and even more preferably in the range of 0.024 to 0.069. In this embodiment, the ratio of a predetermined length D to the length of the negative electrode sheet is 0.024 (i.e., 35 mm / 1455 mm). In another embodiment, the ratio of a predetermined length D to the length of the negative electrode sheet is 0.017 (i.e., 25 mm / 1455 mm).

[0028] As shown in Figure 1, in this embodiment, no support member (e.g., a cylindrical body) is provided on either the negative electrode upper surface 120a or the negative electrode lower surface 120b of the negative electrode sheet between the winding start end A1 and 35 mm. This length allows the laminate of the present invention to be wound to function as an electrical cell without the need for a support member, thus providing a lighter battery of the present invention. In the present invention, the cylindrical body can be, for example, a hollow cylindrical body such as an iron rod.

[0029] The laminate of this embodiment comprises a plurality of positive electrode tabs 170 and a plurality of negative electrode tabs 130. The plurality of positive electrode tabs 170 are connected to the surface of a positive electrode sheet, and the plurality of negative electrode tabs 130 are connected to the surface of a negative electrode sheet. In this embodiment, the electric cell comprises two positive electrode tabs and three negative electrode tabs. For illustrative purposes, the two positive electrode tabs are referred to as the first positive electrode tab 170a and the second positive electrode tab 170b, respectively, and the three negative electrode tabs are referred to as the first negative electrode tab 130a, the second negative electrode tab 130b, and the third negative electrode tab 130c, respectively. In this embodiment, the first positive electrode tab 170a and the second positive electrode tab 170b are positioned on the positive electrode upper surface 160a and provided in an area not covered by the positive electrode coating, while the first negative electrode tab 130a, the second negative electrode tab 130b, and the third negative electrode tab 130c are positioned on the negative electrode upper surface 120a and provided in an area not covered by the negative electrode coating. In this embodiment, one end of each of the first positive electrode tab 170a and the second positive electrode tab 170b is connected to the positive electrode upper surface 160a, and the other end extends outward from one end of the winding body and is later electrically connected to the positive electrode. One end of each of the first negative electrode tab 130a, the second negative electrode tab 130b, and the third negative electrode tab 130c is connected to the negative electrode upper surface 120a, and the other end extends outward from the other end of the winding body and is later electrically connected to the negative electrode. In some embodiments, the laminate comprises two positive electrode tabs and two negative electrode tabs. In the present invention, the positive electrode tabs and negative electrode tabs can vary according to battery requirements or battery design and can have different numbers or configurations.

[0030] In some embodiments, the negative electrode tab and the positive electrode tab are connected to the negative electrode sheet and the positive electrode sheet by welding, respectively. The welding is preferably ultrasonic welding. In the present invention, the negative electrode tab may be a metal foil of copper foil, nickel foil, or copper-nickel alloy, and the positive electrode tab may be an aluminum foil. In this embodiment, the negative electrode tab is copper foil, and the positive electrode tab is aluminum foil.

[0031] Figure 2 shows X-ray computed tomography images of cross-sections of an electric cell 100 according to an embodiment of the present invention, taken along different cross-sectional lines II. The ratio of a predetermined length D to the length of the negative electrode sheet in the electric cell 100 is 0.024 (i.e., 35 mm / 1455 mm), and the position of cross-sectional line II relative to the winding is shown in the lower right of each figure. Figure 2 was obtained by testing under test conditions of a charge / discharge rate (C rate) of 1C / 100W, a voltage of 2.65V to 4.2V, and a cutoff temperature of 95°C in the termination state. Figure 3 shows X-ray computed tomography images of cross-sections of an electric cell of a comparative example, taken along different cross-sectional lines II. The ratio of a predetermined length D in the electric cell to the length of the negative electrode sheet is 0.011 (i.e., 16 mm / 1455 mm), and the position of cross-sectional line II relative to the winding is shown in the lower right of each figure. Figure 3 shows the results obtained under the same test conditions as Figure 2, namely, a charge / discharge rate (C rate) of 1C / 100W, a voltage of 2.65V to 4.2V, and a cutoff temperature of 95°C at the end of the cycle. As can be seen from the results in Figures 2 and 3, by increasing the uncovered area of ​​the negative electrode sheet starting from the winding start end (i.e., increasing the ratio of the uncovered area to be approximately the same as the winding end of the negative electrode sheet), the temperature of the center of the winding can be lowered more quickly by heat dissipation, solving the problem of stress concentration in the coil inside the electrical cell due to heat, preventing deformation and wrinkles in the electrical cell, and thereby increasing the stability of the battery and extending its lifespan.

[0032] Figure 4 shows the analysis results of numerical values ​​indicating the center temperature of the electric cell when (a) the ratio of the predetermined length D to the length of the negative electrode sheet is 0.011 (comparative example), (b) the ratio of the predetermined length D to the length of the negative electrode sheet is 0.017, and (c) the ratio of the predetermined length D to the length of the negative electrode sheet is 0.024. As shown in Figure 4, by increasing the proportion of the negative electrode coated area that is not covered by the negative electrode slurry at the winding start end of the electric cell of the present invention, the winding center temperature can be lowered more quickly by heat dissipation, stress concentration can be reduced, and the stability of the battery can be significantly improved.

[0033] The present invention further provides a battery. Figure 5 is a schematic diagram of the battery of the present invention. In this embodiment, the battery is a cylindrical lithium battery 10. The cylindrical lithium battery 10 comprises a housing 20, a positive electrode terminal 30, a negative electrode terminal 40, and an electrical cell 110. The housing 20 comprises a lid 22, a can 26, and a housing space 28 formed by sealing and joining the lid 22 and the can 26 together, which communicates from top to bottom. The positive electrode terminal 30 is embedded in the lid 22, the negative electrode terminal 40 is embedded in the can 26, and the electrical cell 110 is obtained by winding the laminate described above starting from the winding start end A1, and is placed in the housing space 28. The electrical cell 110 is electrically connected to the positive electrode terminal 30 via a positive electrode tab 170 (not shown), and the electrical cell 110 is electrically connected to the negative electrode terminal 40 via a negative electrode tab 130 (not shown).

[0034] As described above, by configuring the proportion of the uncovered area on the winding start end side of the negative electrode sheet to be within a predetermined range, the problem of thermal stress concentration in the electric cell can be effectively solved without impairing electrical capacity, and the stability of the battery can be significantly improved. Furthermore, the electric cell of the present invention does not require the additional provision of a cylindrical body as a support member, as in the prior art. Therefore, the weight and space of the battery can be reduced without affecting the performance of the battery (e.g., electrical capacity), and thus the objectives of weight reduction and thinning can be achieved.

[0035] Although the present invention has been described above using specific details to clarify its nature, it should be understood that various changes and modifications can be made within the scope of the claims. Therefore, the above embodiments are for illustrative purposes only and should not be construed as limiting. Furthermore, the present invention is not bound by the details described herein and can be modified without departing from the claims or their equivalents.

Claims

1. An electric cell which is a wound body formed by winding a laminate, wherein the laminate is A positive electrode sheet is a positive electrode substrate having a positive electrode upper surface and a positive electrode lower surface opposite to the positive electrode upper surface, wherein at least one of the positive electrode upper surface and the positive electrode lower surface has a positive electrode coating, and A negative electrode sheet is a negative electrode substrate having a negative electrode upper surface and a negative electrode lower surface opposite to the negative electrode upper surface, wherein at least one of the negative electrode upper surface and the negative electrode lower surface has a negative electrode coating, and at least one of the negative electrode upper surface and the negative electrode lower surface does not have the negative electrode coating for a predetermined length from the winding start end of the negative electrode sheet, and the ratio of the predetermined length to the length of the negative electrode sheet is in the range of 0.015 to 0.055, and A separator is disposed between the positive electrode sheet and the negative electrode sheet, A positive electrode tab connected to the upper surface or lower surface of the positive electrode, An electric cell comprising a negative electrode tab connected to the upper surface of the negative electrode or the lower surface of the negative electrode.

2. The electric cell according to claim 1, wherein at least one of the upper surface of the negative electrode and the lower surface of the negative electrode is not provided with a support member between the winding start end and the predetermined length.

3. The electric cell according to claim 2, wherein the support member is not provided on either the upper surface of the negative electrode or the lower surface of the negative electrode between the winding start end and the predetermined length.

4. The electrocellular cell according to claim 1, wherein the ratio of the predetermined length to the length of the negative electrode sheet is in the range of 0.017 to 0.

045.

5. The electric cell according to claim 1, wherein the negative electrode coating is not provided on either the upper surface of the negative electrode or the lower surface of the negative electrode between the winding start end and the predetermined length.

6. The electric cell according to claim 1, wherein the positive electrode tab comprises a first positive electrode tab and a second positive electrode tab, and both the first positive electrode tab and the second positive electrode tab are connected to the upper surface of the positive electrode.

7. The electrical cell according to claim 1, wherein the negative electrode tab comprises a first negative electrode tab, a second negative electrode tab, and a third negative electrode tab, and all of the first negative electrode tab, the second negative electrode tab, and the third negative electrode tab are connected to the upper surface of the negative electrode.

8. A housing comprising a lid, a can, and a storage space formed by the sealing and joining of the lid and the can, The positive terminal embedded in the cover and The negative terminal embedded in the aforementioned can, A battery comprising an electrical cell according to claim 1, which is disposed within the aforementioned housing space, connected to the positive terminal via the positive tab, and connected to the negative terminal via the negative tab.

9. Furthermore, the battery according to claim 8, comprising an electrolyte disposed within the containment space.

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