NESTED STRUCTURE LITHIUM ION BATTERY CAPABLE OF REDUCING RISK OF THERMAL RUNAWAY

Abstract

A nested structure lithium ion battery capable of reducing a risk of thermal runaway includes a metal housing and a battery cell filled in the housing. The housing includes an inner cylinder and an outer cylinder. The inner cylinder is located in a through hole in the center of the outer cylinder, and there is a gap between a side wall of the inner cylinder and a secondary outer wall of the outer cylinder. The battery cell includes an outer battery cell and an inner battery cell. The outer battery cell is filled in a cavity of the outer cylinder, and the inner battery cell is filled in a cavity of the inner cylinder. This nested structure lithium ion battery divides the battery cell into two parts. The gap is used as a heat dissipation channel in a high temperature environment.

Claims

1. A nested structure lithium ion battery capable of reducing a risk of thermal runaway, wherein the nested structure lithium ion battery comprises a metal housing and a battery cell filled in the housing; the housing comprises an inner cylinder and an outer cylinder, both of which are a cylindrical structure with a bottom and without a cover, wherein the outer cylinder comprises an outer wall and a secondary outer wall, an end face of the outer cylinder is ring-shaped, the inner cylinder is located in a through hole in the center of the outer cylinder, there is a gap between a side wall of the inner cylinder and the secondary outer wall of the outer cylinder, and a metal connecting rib is arranged in the gap to fixedly connect the inner cylinder and the outer cylinder as a whole and conduct; the battery cell comprises an outer battery cell and an inner battery cell, the outer battery cell is filled in a cavity of the outer cylinder, and the inner battery cell is filled in a cavity of the inner cylinder; a lower end of the outer battery cell is connected with a bottom plate of the outer cylinder through an outer battery cell lower pole piece to conduct; an upper end opening of the outer cylinder is provided with a first battery protection assembly, and an upper end of the outer battery cell is connected with an outer battery cell electrode cap arranged on an upper surface of the first battery protection assembly through an outer battery cell upper pole piece to conduct; a lower end of the inner battery cell is connected with a bottom plate of the inner cylinder through an inner battery cell lower pole piece to conduct; and an upper end opening of the inner cylinder is provided with a second battery protection assembly, and an upper end of the inner battery cell is connected with an inner battery cell electrode cap arranged on an upper surface of the second battery protection assembly through an inner battery cell upper pole piece to conduct.

2. The nested structure lithium ion battery capable of reducing the risk of thermal runaway according to claim 1, wherein the inner cylinder, the outer cylinder and the connecting rib are integrally formed.

3. The nested structure lithium ion battery capable of reducing the risk of thermal runaway according to claim 1, wherein the outer cylinder is a cylindrical or cubic housing.

4. The nested structure lithium ion battery capable of reducing the risk of thermal runaway according to claim 3, wherein the electrode polarities of the outer battery cell upper pole piece and the inner battery cell upper pole piece are the same, and the outer battery cell and the inner battery cell are connected in parallel through the housing.

5. The nested structure lithium ion battery capable of reducing the risk of thermal runaway according to claim 4, wherein after the outer battery cell and the inner battery cell are connected to a circuit in parallel through the housing, there are three working states as follows: 1) while two wiring terminals in the circuit are respectively connected with the housing and the inner battery cell electrode cap to conduct, the inner battery cell is in the working state, and the outer battery cell does not work; 2) while the two wiring terminals in the circuit are respectively connected with the housing and the outer battery cell electrode cap to conduct, the outer battery cell is in the working state, and the inner battery cell does not work; and 3) while one wiring terminal in the circuit is connected with the inner battery cell electrode cap and the outer battery cell electrode cap to conduct at the same time, and the other wiring terminal is connected with the battery housing to conduct, the outer battery cell and the inner battery cell work simultaneously after being connected in parallel.

6. The nested structure lithium ion battery capable of reducing the risk of thermal runaway according to claim 3, wherein the electrodes of the outer battery cell upper pole piece and the inner battery cell upper pole piece are different, and the outer battery cell and the inner battery cell are connected in series through the housing.

7. The nested structure lithium ion battery capable of reducing the risk of thermal runaway according to claim 6, wherein after the outer battery cell and the inner battery cell are connected to a circuit in series through the housing, there are three working states as follows: 1) while two wiring terminals in the circuit are respectively connected with the housing and the inner battery cell electrode cap to conduct, the inner battery cell is in the working state, and the outer battery cell does not work; 2) while the two wiring terminals in the circuit are respectively connected with the housing and the outer battery cell electrode cap to conduct, the outer battery cell is in the working state, and the inner battery cell does not work; and 3) while the two wiring terminals in the circuit are respectively connected with the inner battery cell electrode cap and the outer battery cell electrode cap to conduct, the outer battery cell and the inner battery cell work simultaneously after being connected in series.

8. The nested structure lithium ion battery capable of reducing the risk of thermal runaway according to claim 1, wherein the gap between the side wall of the inner cylinder and the secondary outer wall of the outer cylinder is filled with a heat conduction material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is a top view of a nested structure lithium ion battery in Embodiment I of the present invention.

[0033] FIG. 2 is an A-A cross-sectional view of FIG. 1.

[0034] FIG. 3 is a top view of a nested structure lithium ion battery with a cylindrical outer cylinder of the present invention.

[0035] FIG. 4 is a top view of a nested structure lithium ion battery in Embodiment II of the present invention.

[0036] FIG. 5 is a B-B cross-sectional view of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

[0037] Technical schemes in embodiments of the present invention are clearly and completely described below in combination with drawings in the embodiments of the present invention.

Embodiment I

[0038] As shown in FIGS. 1 and 2, a nested structure lithium ion battery capable of reducing a risk of thermal runaway, including a metal housing 1 and a battery cell 2 filled in the housing.

[0039] The housing 1 includes an inner cylinder 101 and an outer cylinder 102, both of which are a cylindrical structure with a bottom and without a cover, herein the outer cylinder 102 includes an outer wall 1022 and a secondary outer wall 1021, an end face of the outer cylinder 102 is ring-shaped, the inner cylinder 101 is located in a through hole in the center of the outer cylinder 102, there is a gap 3 between a side wall of the inner cylinder 101 and the secondary outer wall 1021 of the outer cylinder, and a metal connecting rib 4 is arranged in the gap 3 to fixedly connect the inner cylinder 101 and the outer cylinder 102 as a whole and conduct through the metal connecting rib 4.

[0040] The battery cell 2 includes an outer battery cell 202 and an inner battery cell 201, the outer battery cell 202 is filled in a ring-shaped cavity of the outer cylinder 102, and the inner battery cell 201 is filled in a cavity of the inner cylinder 101; a lower end of the outer battery cell 202 is connected with a bottom plate of the outer cylinder 102 through an outer battery cell lower pole piece 802 to conduct; an upper end opening of the outer cylinder 102 is provided with a first battery protection assembly 602, and an upper end of the outer battery cell 202 is connected with an outer battery cell electrode cap 502 arranged on an upper surface of the first battery protection assembly 602 through an outer battery cell upper pole piece 702 to conduct, and the outer battery cell electrode cap 502 is ring-shaped; a lower end of the inner battery cell 201 is connected with a bottom plate of the inner cylinder 101 through an inner battery cell lower pole piece 801 to conduct; and an upper end opening of the inner cylinder 101 is provided with a second battery protection assembly 601, and an upper end of the inner battery cell 201 is connected with an inner battery cell electrode cap 501 arranged on an upper surface of the second battery protection assembly 601 through an inner battery cell upper pole piece 701 to conduct. The first battery protection assembly and the second battery protection assembly are not connected, and are two independent insulating assemblies.

[0041] In this application, by designing the housing of the lithium ion battery as an inner and outer nested structure, there is a gap between the inner cylinder and the outer cylinder, but the two are connected by the metal connecting rib integrally formed with the housing, and they are still essentially a whole. The outer battery cell and the inner battery cell are conducted through the metal housing. By changing the connection type of the positive and negative electrodes of the outer battery cell and the inner battery cell with the housing, the two battery cells may achieve the series connection or parallel connection.

[0042] This inner and outer nested structure may further increase the geometric size of a single lithium ion battery, so that the overall energy density of the battery pack is increased. Although the interior of this nested lithium ion battery is divided into two battery cells, the outer battery cell and the inner battery cell are connected through the housing to conduct, without the need for other external assemblies to connect. This structure is convenient for the connection of the outer battery cell and the inner battery cell on the one hand, and makes the working state of the outer battery cell and the inner battery cell in a separable and combinable state on the other hand, so options while the battery pack is assembled are increased.

[0043] The battery cell of the lithium ion battery related in the present invention is an ordinary winding battery cell, and the structure of the battery protection assembly is similar to the structure of a safety protection device of an ordinary cylindrical lithium ion battery, except that the shape is changed according to the need for the nested battery related in the present invention.

[0044] In this embodiment, the inner cylinder 101, the outer cylinder 102 and the connecting rib 4 are integrally formed, the structural stability is good.

[0045] In this embodiment, the outer cylinder is cubic, and edges are rounded. As shown in FIG. 1, the inner cylinder is cylindrical, namely the end face is a circular ring. In other embodiments, the outer cylinder and the inner cylinder are both cylindrical, as shown in FIG. 3.

[0046] In this embodiment, the electrodes of the outer battery cell upper pole piece 702 and the inner battery cell upper pole piece 701 are the same, and both are the positive electrodes; and the inner battery cell lower pole piece 801 and the outer battery cell lower pole piece 802 are conducted with the housing, and both are the negative electrodes, the outer battery cell and the inner battery cell are connected in parallel through the housing. In other embodiments, the electrodes of the outer battery cell upper pole piece and the inner battery cell upper pole piece are the same, and may be the negative electrodes at the same time; and the lower pole piece of the inner battery cell and the lower pole piece of the outer battery cell are conducted with the housing, and both are the positive electrodes.

[0047] After the outer battery cell and the inner battery cell are connected to a circuit in parallel through the housing, there are three working states as follows:

[0048] 1) while two wiring terminals in the circuit are respectively connected with the housing and the inner battery cell electrode cap to conduct, the inner battery cell is in the working state, and the outer battery cell does not work;

[0049] 2) while the two wiring terminals in the circuit are respectively connected with the housing and the outer battery cell electrode cap to conduct, the outer battery cell is in the working state, and the inner battery cell does not work; and

[0050] 3) while one wiring terminal in the circuit is connected with the inner battery cell electrode cap and the outer battery cell electrode cap to conduct at the same time, and the other wiring terminal is connected with the battery housing to conduct, the outer battery cell and the inner battery cell work simultaneously after being connected in parallel.

[0051] In other embodiments, the electrodes of the outer battery cell upper pole piece 702 and the inner battery cell upper pole piece 701 are different, the outer battery cell upper pole piece is the positive electrode, the inner battery cell upper pole piece is the negative electrode, the inner battery cell lower pole piece is the positive electrode, and the outer battery cell lower pole piece is the negative electrode, so the outer battery cell and the inner battery cell achieve the series connection through the battery housing, the inner battery cell electrode cap is the negative electrode of the battery, and the outer battery cell electrode cap is the positive electrode of the battery.

[0052] Alternatively, the electrodes of the outer battery cell upper pole piece and the inner battery cell upper pole piece are different, the outer battery cell upper pole piece is the negative electrode, the inner battery cell upper pole piece is the positive electrode, the inner battery cell lower pole piece is the negative electrode, and the outer battery cell lower pole piece is the positive electrode, so the outer battery cell and the inner battery cell achieve the series connection through the battery housing, the inner battery cell electrode cap is the positive electrode of the battery, and the outer battery cell electrode cap is the negative electrode of the battery.

[0053] After the outer battery cell and the inner battery cell are connected to a circuit in parallel through the housing, there are three working states as follows:

[0054] 1) while two wiring terminals in the circuit are respectively connected with the housing and the inner battery cell electrode cap to conduct, the inner battery cell is in the working state, and the outer battery cell does not work;

[0055] 2) while the two wiring terminals in the circuit are respectively connected with the housing and the outer battery cell electrode cap to conduct, the outer battery cell is in the working state, and the inner battery cell does not work; and

[0056] 3) while the two wiring terminals in the circuit are respectively connected with the inner battery cell electrode cap and the outer battery cell electrode cap to conduct, the outer battery cell and the inner battery cell work simultaneously after being connected in series.

[0057] Therefore, while the nested battery described in this application is used for grouping, different voltages and a plurality of charging-discharging strategies may be achieved under the same connection scheme by selecting the lithium ion batteries of different assembly forms, and the intermittent operation of the outer battery cell and the inner battery cell may be achieved, so the continuous working temperature of the overall battery pack is reduced.

[0058] Since there is the gap 3 between the outer battery cell and the inner battery cell of the battery, the gap may serve as an air-cooled heat-dissipating air duct, so that the heat generated during the charging-discharging of the battery cell may be taken away by the air flowing through this gap. In addition to serving as the air duct, this gap also plays a role in reducing the thickness of the battery cell, so the thicknesses of the inner and outer battery cells are not too high, so that the heat may be transferred to the battery housing in time and be taken away by a heat-dissipating system, but the size of the battery may be made larger.

[0059] In the nested battery related to the present invention, since the battery is divided into two battery cells, and there is the gap 3 between the two parts, after the battery is subjected to an external mechanical acting force, there is a crumple space inside the battery, which may offset the external mechanical damage through deformation, and protect the safety of the overall battery pack.

Embodiment II

[0060] In this embodiment, as shown in FIGS. 4 and 5, the gap 3 between the side wall of the inner cylinder and the secondary outer wall of the outer cylinder is filled with a heat conduction material 9. The purpose of filling the heat conduction material 9 is to make the heat between the outer battery cell and the inner battery cell conduct, this type of the battery is not suitable for assembling in the battery pack that often works in the high temperature environment, but it is very suitable for assembling in the battery pack that often works in the low temperature environment.

[0061] In the low temperature environment, while the battery is enabled, the temperature is too low, it is easy to cause the significant decrease in battery performance, and it is easy to shorten the battery life and reduce the battery stability and safety in the long run. Therefore, in the low temperature environment, the using strategy of this nested battery is different from that of an ordinary lithium ion battery. While it is just enabled, only the inner battery cell 201 is used for work, so that a working current per unit volume of the battery cell is relatively large, and the inner battery cell generates the heat apparently. Since the inner battery cell 201 is wrapped by the heat conduction material 9, most of the heat generated is transferred to the outer battery cell 201 through the heat conduction material 9, and the outer battery cell 202 is heated. After the temperature of the outer battery cell 202 rises to a normal working temperature, the outer battery cell 202 is used for work, and the work of the inner battery cell 201 is temporarily stopped, or the two battery cells work at the same time, so that the temperature of the battery may be adjusted in a variety of ways. This type of the nested battery has the high heat use efficiency, and may heat the battery pack without the need for an additional heating device.

[0062] The other parts are the same as in Embodiment I.

[0063] It should be understood that the specific embodiments described here are only used to explain the present invention, but not to limit the present invention; and any modifications, equivalent replacements, improvements and the like made within the spirit and principle of the present invention shall be included in a scope of protection of the present invention.