Secondary batteries

Abstract

To provide a secondary battery capable of suppressing metal precipitation inside an electric cell.SOLUTION: A secondary battery 1 includes a conductive electric tank 10, a negative electrode collection terminal 12 housed in the electric tank 10, a conductive part 14 disposed between the negative electrode collection terminal 12 and the electric tank 10 in the electric tank 10, and an insulating part 15 that insulates one of the negative electrode collection terminal 12 and the electric tank 10 and the conductive part 14. The conductive part 14 electrically connects the negative electrode collection terminal 12 and the electric tank 10 by the insulating part 15 being melted.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a secondary battery. [Background technology]

[0002] Currently, secondary batteries such as lithium-ion batteries are used in electric vehicles, hybrid vehicles, plug-in hybrid vehicles, etc. In such secondary batteries, metals generated from metal ions such as lithium ions that are not accommodated in the negative electrode due to overcharging may precipitate as dendrites, potentially causing a short circuit between the positive and negative electrodes.

[0003] In this regard, Patent Document 1 discloses a secondary battery including a stacked electrode assembly including a positive electrode plate, a negative electrode plate, and a first separator, a battery container charged to the positive electrode potential, and a wall resin disposed between the stacked electrode assembly and the battery container. In this secondary battery, the wall resin melts at a temperature lower than the melting temperature of the first separator, thereby short-circuiting the battery container and the negative electrode plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-138287 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the secondary battery disclosed in Patent Document 1 has the problem that if a micro-short circuit due to metal precipitation actually occurs, i.e., if a short circuit occurs between the positive and negative electrodes, the wall resin melts and the battery container and the negative electrode plate are short-circuited, and therefore metal precipitation cannot be suppressed within the battery container.

[0006] The present disclosure is intended to solve such problems, and has an object to provide a secondary battery that can suppress metal deposition inside the battery case. [Means for solving the problem]

[0007] The secondary battery according to one embodiment comprises: a conductive battery container; a negative electrode current collector terminal housed in a battery case; a conductive portion disposed between the negative electrode current collector terminal and the battery case within the battery case; an insulating part that insulates the conductive part from either the negative electrode current collector terminal or the battery case; Equipped with The conductive portion electrically connects the negative electrode current collector terminal and the battery case by melting the insulating portion.

[0008] The insulating portion can melt at the temperature of the negative electrode current collector terminal when the secondary battery is overcharged in a state where no short circuit occurs between the positive electrode and the negative electrode.

[0009] When the conductive part is fixed to the battery case and the insulating part insulates the negative electrode current collector terminal from the conductive part, The conductive portion may be configured to press the insulating portion against the negative electrode current collector terminal.

[0010] When the insulating portion melts, the conductive portion comes into contact with the negative electrode current collector terminal, and can electrically connect the negative electrode current collector terminal and the battery case.

[0011] When the conductive part is fixed to the negative electrode current collector terminal and the insulating part insulates the battery case from the conductive part, The conductive portion may be configured to press the insulating portion against the battery case.

[0012] When the insulating portion melts, the conductive portion comes into contact with the battery case, and can electrically connect the negative electrode current collector terminal and the battery case.

[0013] The battery case may be formed from a conductive material.

[0014] The battery case is provided with a conductive plate, the insulating portion insulates the conductive portion from either the negative electrode current collecting terminal or the conductive plate; The conductive portion can electrically connect the negative electrode current collector terminal and the conductive plate by melting the insulating portion.

[0015] The battery contains an electrolyte solution, The liquid level of the electrolyte is equal to or higher than the level of the bottom of the electrode body of the secondary battery. [Effects of the Invention]

[0016] According to the present disclosure, a secondary battery capable of suppressing metal deposition inside the battery case can be provided. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a perspective view showing a secondary battery according to an embodiment; [Figure 2] 1 is a front view showing a secondary battery according to an embodiment; [Figure 3] FIG. 10 is a diagram showing the temperature of a secondary battery during overcharge in a state where no short circuit occurs between the positive electrode and the negative electrode. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment will be described below with reference to the drawings. Fig. 1 is a perspective view showing a secondary battery 1 according to one embodiment. The secondary battery 1 includes a battery case 10 that houses an electrode assembly. A negative electrode external terminal 20 and a positive electrode external terminal 30 that are electrically connected to the electrode assembly are disposed on the top surface of the battery case 10. In this embodiment, the battery case 10 is made of a conductive material such as metal and has conductivity.

[0019] 2 is a front view showing a secondary battery 1 according to one embodiment. In order to illustrate the interior of a battery case 10 of the secondary battery 1, the front side wall of the battery case 10 is omitted in FIG. 2. As shown in FIG. 2, the secondary battery 1 includes an electrode body 11, a negative electrode current collector terminal 12, a positive electrode current collector terminal 13, a conductive part 14, and an insulating part 15. These components are housed inside the battery case 10.

[0020] The electrode body 11 is formed by laminating a negative electrode sheet 11a, a positive electrode sheet 11b, and a separator that insulates the negative electrode sheet 11a and the positive electrode sheet 11b.

[0021] The negative electrode current collector terminal 12 is connected to the negative electrode sheet 11a and the negative electrode external terminal 20, and is a conductive part that enables electrical conduction between the negative electrode sheet 11a and the negative electrode external terminal 20. In this embodiment, the negative electrode current collector terminal 12 is connected to the negative electrode sheet 11a so as to sandwich the negative electrode sheet 11a from both sides in the thickness direction of the secondary battery 1. The negative electrode current collector terminal 12 is also connected to the negative electrode sheet 11a and the negative electrode external terminal 20 on one side in the width direction of the secondary battery 1. Note that in other embodiments, the negative electrode current collector terminal 12 may be connected to the negative electrode sheet 11a and the negative electrode external terminal 20 on one side in the height direction of the secondary battery 1.

[0022] The positive electrode current collector terminal 13 is connected to the positive electrode sheet 11b and the positive electrode external terminal 30, and is a conductive part that enables electrical conduction between the positive electrode sheet 11b and the positive electrode external terminal 30. In this embodiment, the positive electrode current collector terminal 13 is connected to the positive electrode sheet 11b so as to sandwich the positive electrode sheet 11b from both sides in the thickness direction of the secondary battery 1. The positive electrode current collector terminal 13 is also connected to the positive electrode sheet 11b and the positive electrode external terminal 30 on the other side in the width direction of the secondary battery 1. Note that in other embodiments, the positive electrode current collector terminal 13 may be connected to the positive electrode sheet 11b and the positive electrode external terminal 30 on one side in the height direction of the secondary battery 1.

[0023] The conductive part 14 is disposed between the negative electrode current collector terminal 12 and the battery case 10 and is a conductive part that enables electrical conduction between the negative electrode current collector terminal 12 and the battery case 10. In this embodiment, the conductive part 14 is fixed to the battery case 10. For example, the conductive part 14 can be fixed to a side wall of the battery case 10. In this embodiment, as shown in FIG. 2 , the conductive part 14 is fixed to a side wall that exists in the width direction of the secondary battery 1, but in other embodiments, the conductive part 14 may be fixed to a side wall that exists in the thickness direction of the secondary battery 1.

[0024] The insulating part 15 is a non-conductive part that insulates the negative electrode current collector terminal 12 from the conductive part 14. The insulating part 15 is made of a non-conductive material that melts at the temperature of the negative electrode current collector terminal 12 when the secondary battery 1 is overcharged. Examples of non-conductive materials that form the insulating part 15 include polyethylene, polypropylene, polystyrene, nylon 6, and ABS (Acrylonitrile Butadiene Styrene) resin.

[0025] In this embodiment, the insulating portion 15 is formed on the conductive portion 14. The conductive portion 14 is configured to press the insulating portion 15 against the negative electrode current collector terminal 12. A specific example of the conductive portion 14 is an elastic member such as a leaf spring.

[0026] The insulating portion 15 melts at the temperature of the negative electrode current collector terminal 12 when the secondary battery 1 is overcharged without a short circuit between the positive and negative electrodes. FIG. 3 is a diagram showing the temperature when the secondary battery 1 is overcharged without a short circuit between the positive and negative electrodes. As shown in FIG. 3, the temperature of the negative electrode current collector terminal 12 increases as the voltage of the secondary battery 1 increases. In this embodiment, the insulating portion 15 contacts the negative electrode current collector terminal 12, and therefore melts due to the increase in temperature of the negative electrode current collector terminal 12 when the secondary battery 1 is overcharged. When the insulating portion 15 melts, the conductive portion 14 comes into contact with the negative electrode current collector terminal 12, electrically connecting the negative electrode current collector terminal 12 and the battery case 10. Note that the portion of the insulating portion 15 in contact with the negative electrode current collector terminal 12 is more likely to melt due to heat transferred from the negative electrode current collector terminal 12.

[0027] As described above, the secondary battery 1 includes a conductive battery case 10, a negative electrode current collector terminal 12 housed in the battery case 10, a conductive part 14 disposed between the negative electrode current collector terminal 12 and the battery case 10 within the battery case 10, and an insulating part 15 that insulates the negative electrode current collector terminal 12 from the conductive part 14. The conductive part 14 electrically connects the negative electrode current collector terminal 12 and the battery case 10 when the insulating part 15 melts. The insulating part 15 melts at the temperature of the negative electrode current collector terminal 12 when the secondary battery 1 is overcharged in a state where no short circuit occurs between the positive and negative electrodes.

[0028] With this configuration, when the temperature of the negative electrode current collector terminal 12 reaches the above temperature during overcharge of the secondary battery 1, the insulating portion 15 melts, electrically connecting the negative electrode current collector terminal 12 and the battery case 10. Typically, the potential of the battery case 10 is higher than the potential of the negative electrode sheet 11a and the negative electrode current collector terminal 12, so metal ions such as lithium ions preferentially move to the battery case 10 rather than the negative electrode sheet 11a. This makes it possible to suppress the deposition of metals such as lithium on the surface of the negative electrode sheet 11a. In particular, the present disclosure is useful because it can suppress the deposition of metals such as lithium without making any changes to the design of the electrode body, such as the particle size of the negative electrode active material, the specific surface area of ​​the negative electrode, or the capacity ratio between the negative electrode and the positive electrode.

[0029] Furthermore, the conductive portion 14 is configured to press the insulating portion 15 against the negative electrode current collector terminal 12. This allows the insulating portion 15 to melt, thereby ensuring that the conductive portion 14 comes into contact with the negative electrode current collector terminal 12.

[0030] Furthermore, an electrolyte is stored in the battery case 10. The liquid level Le of the electrolyte can be set to a level Lb or higher of the bottom 16 of the electrode body 11, as shown in FIG. 2. This allows metal ions such as lithium ions to reliably migrate into the battery case 10.

[0031] The present disclosure is not limited to the above-described embodiment and can be modified as appropriate without departing from the spirit and scope of the present disclosure. For example, in another embodiment, instead of fixing the conductive portion 14 to the battery case 10, the conductive portion 14 may be fixed to the negative electrode current collector terminal 12. In this case, the insulating portion 15 insulates the battery case 10 from the conductive portion 14. The conductive portion 14 is configured to press the insulating portion 15 against the battery case 10. In this embodiment, heat transferred from the negative electrode current collector terminal 12 via the conductive portion 14 melts the insulating portion 15, bringing the conductive portion 14 into contact with the battery case 10 and electrically connecting the negative electrode current collector terminal 12 and the battery case 10. As a result, metal ions such as lithium ions preferentially migrate to the battery case 10 rather than to the negative electrode sheet 11a, thereby suppressing the deposition of metals such as lithium on the surface of the negative electrode sheet 11a.

[0032] In another embodiment, the battery case 10 may include a conductive plate made of a conductive material such as metal. In this case, the conductive portion 14 is fixed to the conductive plate or the negative electrode current collector terminal 12. When the conductive portion 14 is fixed to the conductive plate, the insulating portion 15 insulates the negative electrode current collector terminal 12 from the conductive portion 14, and the conductive portion 14 is configured to press the insulating portion 15 against the negative electrode current collector terminal 12. When the conductive portion 14 is fixed to the negative electrode current collector terminal 12, the insulating portion 15 insulates the conductive portion 14 from the conductive plate, and the conductive portion 14 is configured to press the insulating portion 15 against the conductive plate. Note that the battery case 10 stores an electrolyte solution so that it contacts the conductive plate. In this embodiment, when the insulating portion 15 melts, the conductive portion 14 contacts the negative electrode current collector terminal 12 or the conductive plate, electrically connecting the negative electrode current collector terminal 12 and the conductive plate. As a result, metal ions such as lithium ions can be prevented from migrating from the negative electrode current collector terminal to the conductive plate, and deposition of metals such as lithium on the surface of the negative electrode sheet 11a can be prevented. [Explanation of symbols]

[0033] 1 Secondary battery 10 Battery case 11 Electrode body 11a Negative electrode sheet 11b Positive electrode sheet 12 Negative electrode current collector terminal 13 Positive current collecting terminal 14 Conductive part 15 Insulation section 16 Bottom 20 Negative external terminal 30 Positive external terminal

Claims

1. A secondary battery, a conductive battery container; a negative electrode current collector terminal accommodated in the battery case; a conductive portion disposed between the negative electrode current collector terminal and the battery case within the battery case; an insulating part that insulates the conductive part from either the negative electrode current collecting terminal or the battery case; Equipped with the conductive portion electrically connects the negative electrode current collector terminal and the battery case when the insulating portion melts. Secondary battery.

2. The secondary battery according to claim 1 , wherein the insulating portion melts at a temperature of the negative electrode current collector terminal when the secondary battery is overcharged in a state where no short circuit occurs between the positive electrode and the negative electrode.

3. When the conductive part is fixed to the battery case and the insulating part insulates the negative electrode current collector terminal from the conductive part, The secondary battery according to claim 1 , wherein the conductive portion is configured to press the insulating portion against the negative electrode current collector terminal.

4. The secondary battery according to claim 3 , wherein the conductive portion comes into contact with the negative electrode current collector terminal when the insulating portion melts, thereby electrically connecting the negative electrode current collector terminal and the battery case.

5. When the conductive part is fixed to the negative electrode current collector terminal and the insulating part insulates the battery case from the conductive part, The secondary battery according to claim 1 , wherein the conductive portion is configured to press the insulating portion against the battery case.

6. The secondary battery according to claim 5 , wherein the conductive portion comes into contact with the battery case when the insulating portion melts, thereby electrically connecting the negative electrode current collector terminal and the battery case.

7. The secondary battery according to claim 1 , wherein the battery case is made of a conductive material.

8. The battery case includes a conductive plate; the insulating portion insulates the conductive portion from either the negative electrode current collecting terminal or the conductive plate, The secondary battery according to claim 1 , wherein the conductive portion electrically connects the negative electrode current collector terminal and the conductive plate when the insulating portion melts.

9. The battery container stores an electrolyte solution, The secondary battery according to claim 1 , wherein the liquid level of the electrolyte is equal to or higher than the level of a bottom of an electrode body of the secondary battery.

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