Parallel battery module

The present disclosure provides a parallel battery module comprising a plurality of battery cells, a first current collection connector, and a second current collection connector. The plurality of battery cells are in parallel connection. Each battery cell comprises a conducting top cover plate, a first terminal, a conducting connector, a second terminal, a bare cell, a fuse, and a conducting deformable piece. The first current collection connector and the second current collection connector are disposed on the top of the plurality of battery cells, and are electrically connected to the first terminal and the second terminal of the plurality of battery cells, respectively. When the conducting deformable piece of a battery cell deforms and becomes electrically connected to the conducting connector, the electrical connection between said battery cell and other battery cells is broken by blowing the first current collection connector and/or the second current collection connector.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of Chinese Patent Application No. 201510578118.7, entitled “PARALLEL BATTERY MODULE” and filed on Sep. 12, 2015 in the State Intellectual Property Office of the People's Republic of China (PRC) (SIPO), the disclosure of which is expressly incorporated by reference herein in its entirety.

BACKGROUND

Field

The present disclosure relates generally to the field of energy storage devices, and more particularly, to a parallel battery module.

Background

When a battery is over-charged, the internal heat production and internal pressure of the battery are increased due to the decomposition of the battery electrolyte, which may lead to fire or explosion. As shown inFIG. 1, the structure commonly used by the industry right now to address over-charging is a combination of a conducting deformable piece17and a fuse16. When the battery cell is over-charged and the internal gas pressure reaches a certain level, the conducting deformable piece17deforms such that a first terminal12is electrically connected to a conducting top cover plate11via a conducting connector13. Because a second terminal14is electrically connected to the conducting top cover plate11, an external short circuit can be formed between the first terminal12and the second terminal14, thereby protecting the battery. When the current generated by the external short circuit is too high, it is likely to melt the conducting deformable piece17. When the conducting deformable piece17is melted, the electrolyte inside the bare cell15will be ejected from the position of the conducting deformable piece17and in contact with the air. And at the same time, a high temperature is resulted due to the melting, which may cause a fire at the location of the conducting deformable piece17, leading to a safety breach. To prevent the conducting deformable piece17from being melted, a fuse16is provided at the side of the second terminal14that is in connection with the bare cell15. As a result, when the external short circuit is formed between the first terminal12and the second terminal14to consequently generate a high current, the fuse16is blown, which prevents the battery cell1from being continuously charged to cause a danger of fire or explosion, while ensuring that the conducting deformable piece17is not melted.

Such a solution may solve the problem that a battery cell is over-charged or a battery module with multiple battery cells in series connection is over-charged. However, said solution cannot solve the problem that a battery module with multiple battery cells in parallel connection is over-charged. Referring toFIG. 1andFIG. 6, when the battery cell1is over-charged and gas is produced, the conducting deformable piece17of a battery cell deforms. The first terminal12and the second terminal14of said battery cell1are connected and become equivalent to one single wire. This battery cell1forms an external short circuit on its own. Moreover, other battery cells in parallel will also form external short circuits through the conducting top cover plate11of this battery cell1. As a result, the current flowing through the conducting top cover plate11and the conducting deformable piece17of this battery cell1is a sum of currents of all parallel battery cells, while the fuse16of each battery cell1only withstands its own current. Consequently, the conducting deformable piece17of said battery cell1may melt prior to the fuse16. Thus, the connection of said battery cell1and the main charging circuit cannot be broken, leading to failure of the bare cell15of said battery cell1due to continuous charging.

In such a circumstance, the overcurrent cross sectional area of a single conducting deformable piece17may need be greater than the overcurrent cross sectional area of the fuse16. The overcurrent cross sectional area of the fuse16cannot be too small given the reliability requirement of the fuse16during a normal current and the strength requirement of the fuse16itself. The overcurrent cross sectional area of the fuse16of a battery cell used by the industry at present is typically 3 to 8 mm2.

If the overcurrent cross sectional area of the fuse16is 4 mm2, in an example of three battery cells in parallel connection, when a battery cell1is subject to external short circuit, the conducting deformable piece17of said battery cell1withstands the external short circuit current 3I applied by the three battery cells, while the fuse16only withstands the external short circuit current I of one single battery cell. As a result, the overcurrent cross sectional area of the conducting deformable piece17needs to be more than three times of that of the fuse16, namely at least 12 mm2. Due to the restriction by the battery size, however, the lengthwise and widthwise sizes of the conducting deformable piece17are restricted, and the overcurrent cross sectional area of the conducting deformable piece17cannot be infinitely enlarged.

Similarly, for a battery module with four or more battery cells in parallel connection, the overcurrent cross sectional area of the conducting deformable piece17may need to be greater than 16 mm2, which may be difficult to accommodate due to the restriction by the battery size.

SUMMARY

In view of the problems described above, the objective of the present disclosure is to provide a parallel battery module that can lower the requirement regarding the overcurrent cross sectional area of the conducting deformable piece, ensure that the conducting deformable piece deforms normally when a battery cell is over-charged, and guarantee the over-charging safety of the parallel battery module.

To attain the above objective, the present disclosure provides a parallel battery module, comprising a plurality of battery cells, a first current collection connector, and a second current collection connector.

The plurality of battery cells are arranged in parallel. Each battery cell may include: a conducting top cover plate; a first terminal that is assembled to be insulated from the conducting top cover plate; a conducting connector that is electrically connected to the first terminal and insulated from the conducting top cover plate; a second terminal that has the opposite polarity to the first terminal and is assembled to be electrically connected to the conducting top cover plate; an bare cell that is electrically connected to the first terminal and the second terminal; a fuse that is connected between the first terminal and the bare cell or connected between the second terminal and the bare cell; and a conducting deformable piece that is electrically connected to the conducting top cover plate and is disposed below the conducting connector. When the internal gas pressure of a battery cell reaches a certain level, the conducting deformable piece deforms and becomes electrically connected to the conducting connector such that the first terminal and the second terminal are electrically connected to form an external short circuit.

The first current collection connector is disposed on the top of said plurality of battery cells and is electrically connected to the first terminals of said plurality of battery cells.

The second current collection connector is disposed on the top of said plurality of battery cells and is electrically connected to the second terminals of said plurality of battery cells.

Wherein, when the conducting deformable piece of a battery cell deforms and is electrically connected to the conducting connector, the electrical connection between said battery cell and other battery cells is broken by blowing the first current collection connector and/or the electrical connection between said battery cell and other battery cells is broken by blowing the second current collection connector.

The present disclosure has the following advantageous effects:

In the parallel battery module according to the present disclosure, when one battery cell is over-charged and when the conducting deformable piece deforms and is electrically connected to the conducting connector, the first terminal and the second terminal of said battery cell form an external short circuit via the conducting connector, the conducting deformable piece, and the conducting top cover plate. Other battery cells of the parallel battery module also form an external short circuit via the conducting connector, the conducting deformable piece, and the conducting top cover plate of said battery cell. The produced current first breaks the electrical connection between said battery cell and other battery cells by blowing the first current collection connector and/or breaks the electrical connection between said battery cell and other battery cells by blowing the second current collection connector, namely breaking external short circuits of other battery cells of the parallel battery module such that said over-charged battery cell is no longer charged, while other battery cells of the parallel battery module continue to be charged. The above sequence of events is repeated when a battery cell of the parallel battery module is subsequently over-charged. As a result, the requirement for the overcurrent cross sectional area of the conducting deformable piece of the parallel battery module is lowered, which ensures that the conducting deformable piece deforms normally without being melted when a battery cell is over-charged, and guarantees the over-charging safety of each battery cell of the parallel battery module.

DETAILED DESCRIPTION

The present disclosure and the advantageous effects of certain configurations will be further described in detail below with reference to the accompanying drawings and specific embodiments.

The parallel battery module according to the present disclosure will be described in detail below with reference to the accompanying drawings.

Referring toFIG. 1toFIG. 7, the parallel battery module according to the present disclosure comprises a plurality of battery cells1, a first current collection connector2, and a second current collection connector3.

The plurality of battery cells1are arranged in parallel. Each battery cell1comprising: a conducting top cover plate11; a first terminal12that is assembled to be insulated from the conducting top cover plate11; a conducting connector13that is electrically connected to the first terminal12and insulated from the conducting top cover plate11; a second terminal14that has the opposite polarity to the first terminal12and is assembled to be electrically connected to the conducting top cover plate11; an bare cell15that is electrically connected to the first terminal12and the second terminal14; a fuse16that is connected between the first terminal12and the bare cell15or connected between the second terminal14and the bare cell15; and a conducting deformable piece17that is electrically connected to the conducting top cover plate11and is disposed below the conducting connector13. When the internal gas pressure of a battery cell1reaches a certain level, the conducting deformable piece17deforms and becomes electrically connected to the conducting connector13such that the first terminal and the second terminal are electrically connected to form an external short circuit.

The first current collection connector2is disposed on the top of said plurality of battery cells1and is electrically connected to the first terminals12of said plurality of battery cells1.

The second current collection connector3is disposed on the top of said plurality of battery cells1and is electrically connected to the second terminals14of said plurality of battery cells1.

Wherein, when the conducting deformable piece17of a battery cell1deforms and becomes electrically connected to the conducting connector13, the electrical connection between said battery cell1and other battery cells1is broken by blowing the first current collection connector2and/or the electrical connection between said battery cell1and other battery cells1is broken by blowing the second current collection connector3.

In the parallel battery module according to the present disclosure, when one battery cell1is over-charged and when the conducting deformable piece17deforms and becomes electrically connected to the conducting connector13, the first terminal12and the second terminal14of said battery cell1form an external short circuit via the conducting connector13, the conducting deformable piece17, and the conducting top cover plate11. Each of the other battery cells1of the parallel battery module also forms an external short circuit via the conducting connector13, the conducting deformable piece17, and the conducting top cover plate11of said battery cell1. The produced current first breaks the electrical connection between said battery cell1and other battery cells1by blowing the first current collection connector2and/or breaks the electrical connection between said battery cell1and other battery cells1by blowing the second current collection connector3, namely breaking external short circuits of other battery cells of the parallel battery module such that said over-charged battery cell1is no longer charged, while other battery cells of the parallel battery module continue to be charged. The above sequence of events is repeated when a battery cell is subsequently over-charged. As a result, the requirement for the overcurrent cross sectional area of the conducting deformable piece17of the parallel battery module is lowered, which ensures that the conducting deformable piece17deforms normally without being melted when a battery cell1is over-charged, and guarantees the over-charging safety of each battery cell of a parallel battery module.

In the parallel battery module according to the present disclosure, the parallel battery module may be some battery cells in a big battery module that are in parallel connection, or may be all battery cells in a big battery module that are in parallel connection.

In the parallel battery module according to the present disclosure, referring toFIG. 2, in the first embodiment, the first current collection connector2comprises: a plurality of first connection parts21, the number of the first connection parts21being the same as the number of the battery cells1in the parallel battery module, each first connection part21being electrically connected to the first terminal12of a corresponding battery cell1; a first current collection part22; and a plurality of first fusing parts23connected between the first current collection part22and corresponding first connection parts21.

When the conducting deformable piece17of a battery cell1deforms and becomes electrically connected to the conducting connector13, the electrical connection between said battery cell1and other battery cells1is broken by blowing the first fusing part23of the first current collection connector2corresponding to said battery cell1.

In the parallel battery module according to the present disclosure, referring toFIG. 5AandFIG. 5C, in the first embodiment, for one battery cell1, the number of the first fusing part23connected between one first connection part21and the first current collection part22is at least one. A plurality of first fusing parts23for one first connection part21can improve the strength of connection between the first connection part21and the first current collection part22.

In the parallel battery module according to the present disclosure, referring toFIG. 7AandFIG. 7B, in the first embodiment, for one battery cell1, the total overcurrent cross sectional area of all of the first fusing parts23connected between one first connection part21and the first current collection part22is smaller than one half of the contact area between the conducting deformable piece17and the conducting connector13of said battery cell1after the conducting deformable piece17deforms to be in contact with the conducting connector13. Assuming that the number of battery cells1in the parallel battery module is n (n≥2), when one battery cell1is over-charged, the conducting deformable piece17of said battery cell1deforms and forms an external short circuit with the conducting connector13. Each of the other battery cells that are not over-charged also forms an external short circuit via the conducting deformable piece17of said battery cell1. The current produced by the external short circuit of each battery cell is I (one time the current). And at this moment, the current flowing through the conducting deformable piece17is nI (n times the current), while the current flowing through the first fusing part23connected to said battery cell1is (n−1)I. To ensure that said first fusing part23is blown prior to the conducting deformable piece17of said battery cell1, the overcurrent cross sectional area of the first fusing part23is smaller than (n−1)/n of the overcurrent cross sectional area of the contact between the conducting deformable piece17and the conducting connector13. In the present embodiment, the number of the battery cells1is 3 (n=3), then the current flowing through the conducting deformable piece17is 3I, the current flowing through the first fusing part23connected to said battery cell1is 2I. Therefore, the overcurrent cross sectional area of the first fusing part23is smaller than ⅔ of the overcurrent cross sectional area of the contact between the conducting deformable piece17and the conducting connector13. Therefore, it can be seen that, when n=2, the required overcurrent cross sectional area of the contact between the conducting deformable piece17and the conducting connector13is the greatest, namely the total overcurrent cross sectional area of all of the first fusing parts23connected between one first connection part21and the first current collection part22is smaller than one half of the contact area between the conducting deformable piece17and the conducting connector13of said battery cell1after the conducting deformable piece17deforms to be in contact with the conducting connector13.

In the parallel battery module according to the present disclosure, referring toFIG. 5AandFIG. 5B, in the first embodiment, each first fusing part23may be rectangular or S-shaped. In a practical use case of the parallel battery module, the parallel battery module may be subject to external vibration (e.g. shaking or falling). And battery cells1in the parallel battery module may consequently vibrate, which in turn produces a vibration force on the corresponding first current collection connector2. At the same time, the bare cell15of the battery cell1also produce heat and expand, which produces an expansion force on the corresponding first current collection connector2. Under said vibration force and expansion force, the first fusing part23of the first current collection connector2tends to be pulled apart due to the small overcurrent cross sectional area. An S-shaped first fusing part23may reduce the impact of said vibration force and expansion force to prevent the first fusing part23from being pulled apart.

In the parallel battery module according to the present disclosure, referring toFIG. 3, in one embodiment, the second current collection connector3comprises: a plurality of second connection parts31, the number of the second connection parts being the same as the number of the battery cells1in the parallel battery module, each second connection part31being electrically connected to the second terminal14of a corresponding battery cell1; a second current collection part32; and a plurality of second fusing parts33connected between the second current collection part32and corresponding second connection parts31. When the conducting deformable piece17of a battery cell1deforms and becomes electrically connected to the conducting connector13, the electrical connection between said battery cell1and other battery cells1is broken by blowing the second fusing part33of the second current collection connector3corresponding to said battery cell1.

In the parallel battery module according to the present disclosure, referring toFIG. 5AandFIG. 5C, in the second embodiment, for one battery cell1, the number of the second fusing part33connected between one second connection part31and the second current collection part32is at least one. A plurality of first fusing part33for one second connection part31can improve the strength of connection between the second connection part31and the second current collection part32.

In the parallel battery module according to the present disclosure, referring toFIG. 7Aand FIG. B, in the second embodiment, for one battery cell1, the total overcurrent cross sectional area of all of the second fusing parts33connected between one second connection part31and the second current collection part32is smaller than one half of the contact area between the conducting deformable piece17and the conducting connector13of said battery cell1after the conducting deformable piece17deforms to be in contact with the conducting connector13.

In the parallel battery module according to the present disclosure, referring toFIG. 5AandFIG. 5B, in the second embodiment, each second fusing part33may be rectangular or S-shaped. In a practical use case of the parallel battery module, the parallel battery module may be subject to external vibration (e.g. shaking or falling), and battery cells1in the parallel battery module may consequently vibrate, which in turn produces a vibration force on the corresponding second current collection connector3. At the same time, the bare cell15of the battery cell1will also produce heat and expand, which produces an expansion force on the corresponding second current collection connector3. Under said vibration force and expansion force, the first fusing part33of the second current collection connector3tends to be pulled apart due to the small overcurrent cross sectional area. An S-shaped second fusing part33may reduce the impact of said vibration force and expansion force to prevent the second fusing part33from being pulled apart.

In the parallel battery module according to the present disclosure, referring toFIG. 4, in the third embodiment, the first current collection connector2comprises: a plurality of first connection parts21, the number of the first connection parts21being the same as the number of the battery cells1in the parallel battery module, each first connection part configured for electrical connection with the first terminal12of a corresponding battery cell1; a first current collection part22; and a plurality of first fusing parts23configured for connecting the first current collection part22and corresponding first connection parts21.

The second current collection connector3comprises: a plurality of second connection parts31, the number of the second connection parts31being the same as the number of the battery cells1in the parallel battery module, each second connection part31configured for electrical connection with the second terminals14of a corresponding battery cell1; a second current collection part32; and a plurality of second fusing parts33configured for connecting the second current collection part32and corresponding second connection parts31.

When the conducting deformable piece17of a battery cell1deforms and becomes electrically connected to the conducting connector13, the electrical connection between said battery cell1and other battery cells1is broken by blowing all of the first fusing parts23of the first current collection connector2and/or the second fusing parts33of the second current collection connector3corresponding to said battery cell1.

In the parallel battery module according to the present disclosure, referring toFIG. 5AandFIG. 5C, in the third embodiment, for one battery cell1, the number of the first fusing part23connected between one first connection part21and the first current collection part22is at least one, and the number of the second fusing part33connected between one second connection part31and the second current collection part32is at least one. A plurality of first fusing part23can improve the strength of connection between the first connection part21and the first current collection part22, and a plurality of second fusing part33can improve the strength of connection between the second connection part31and the second current collection part32.

In the parallel battery module according to the present disclosure, referring toFIG. 7AandFIG. 7B, in the third embodiment, for one battery cell1, either the total overcurrent cross sectional area of all of the first fusing parts23connected between one first connection part21and the first current collection part22or the total overcurrent cross sectional area of all of the second fusing parts33connected between one second connection part31and the second current collection part32is smaller than one half of the contact area between the conducting deformable piece17and the conducting connector13of said battery cell1after the conducting deformable piece17deforms to be in contact with the conducting connector13.

In the parallel battery module according to the present disclosure, referring toFIG. 5AandFIG. 5B, the first fusing part23may be rectangular or S-shaped, and the second fusing part33may be rectangular or S-shaped. In a practical use case of the parallel battery module, the parallel battery module may be subject to external vibration (e.g. shaking or falling). And battery cells1in the parallel battery module may consequently vibrate, which in turn produces a vibration force on the corresponding first current collection connector2. At the same time, the bare cell15of the battery cell1also produce heat and expand, which produces an expansion force on the corresponding first current collection connector2. Under said vibration force and expansion force, the first fusing part23of the first current collection connector2tends to be pulled apart due to the small overcurrent cross sectional area. An S-shaped first fusing part23may reduce the impact of said vibration force and expansion force to prevent the first fusing part23from being pulled apart. In addition, the battery cells1that produce vibration will similarly produce a vibration force on the corresponding second current collection connector3. At the same time, the bare cell15of the battery cell1also produces heat and expand, which produces an expansion force on the corresponding second current collection connector3. Under said vibration force and expansion force, the second fusing part33of the second current collection connector3tends to be pulled apart due to the small overcurrent cross sectional area. An S-shaped second fusing part33may reduce the impact of said vibration force and expansion force to prevent the second fusing part33from being pulled apart.

In the parallel battery module according to the present disclosure, referring toFIG. 1, in the above plurality of embodiments, the conducting deformable piece17comprises a protrusion171that is disposed in the middle of the conducting deformable piece17and protrudes in a direction toward the conducting connector13such that the protrusion171is electrically connected to the conducting connector13when the conducting deformable piece17deforms. The protrusion171can increase the contact area between the conducting deformable piece17and the conducting connector13after the conducting deformable piece17deforms to be in contact with the conducting connector13, namely increase the overcurrent cross sectional area of the conducting deformable piece17, improve the overcurrent prevention strength of the conducting deformable piece17, and guarantee the over-charging safety of the parallel battery module.

According to the disclosure and description above, those skilled in the art may further make variations and modifications to the above embodiments. Therefore, the present disclosure is not limited by the specific embodiments disclosed and described above. Some equivalent variations and modifications to the present disclosure shall also be encompassed the claims of the present disclosure. Although the Description uses some specific terms, in addition, the terms are used only for the purpose of easy description, which do not constitute any limitation to the present disclosure.