Patent Description:
Secondary batteries that have high ease of application according to product groups and have electrical characteristics such as high energy density, etc. are universally applied to not only portable devices, but also electric vehicles (EVs) or hybrid vehicles (HEVs) driven by an electric drive source. These secondary batteries are attracting attention as a new energy source for improving eco-friendliness and energy efficiency in that not only the primary advantage of being able to dramatically reduce the use of fossil fuels but also the fact that no by-products are generated from the use of energy.

The types of secondary batteries that are currently widely used include a lithium ion battery, a lithium polymer battery, a nickel cadmium battery, a nickel hydrogen battery, a nickel zinc battery, etc. The operating voltage of such a unit secondary battery cell, that is, a unit battery cell, is about <NUM> Vto about <NUM> V. Accordingly, when a higher output voltage is required, a plurality of battery cells are connected in series to configure a battery pack. In addition, a plurality of battery cells are connected in parallel to configure a battery pack according to the charge/discharge capacity required for the battery pack. Accordingly, the number of battery cells included in the battery pack may be set in various ways according to a required output voltage or charge/discharge capacity.

Meanwhile, when a battery pack is configured by connecting a plurality of battery cells in series/parallel, a method of configuring the battery pack by first configuring a battery module including at least one battery cell, and adding other components using the at least one battery module is common.

Since a battery pack of a multi module structure is manufactured in the form in which a plurality of secondary batteries are concentrated in a narrow space, it is important to easily dissipate heat generated from each secondary battery. Since a charging or discharging process of the secondary battery is performed by an electrochemical reaction, if heat of a battery module generated in the charging/discharging process is not effectively removed, heat accumulation occurs and as a result, deterioration of the battery module is accelerated, and in some cases, the battery module may ignite or explode.

Therefore, a high-output and large-capacity battery module and a battery pack mounted thereon necessarily require a cooling device cooling battery cells therein.

The conventional battery module generally employs a cooling structure in which heat is emitted by contacting a thermal interface material (TIM) between battery cells and a heat sink for such cooling.

However, in such a conventional cooling structure, there is a problem in that it is difficult to increase the performance of a battery module and a battery pack, and furthermore, an electric vehicle including the battery module or the battery pack due to low cooling performance.

Further prior art is described in <CIT> and <CIT>.

The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to providing a battery module having a structure capable of maximizing cooling performance and effectively preventing a secondary event such as a thermal runaway phenomenon caused by a high temperature venting gas from occurring when the venting gas is discharged from the battery cell, a battery pack including the battery module, and a vehicle including the battery pack.

In one aspect of the present disclosure, there is provided a battery module including a plurality of cylindrical battery cells disposed upright such that a positive electrode faces downward and a negative electrode faces upward; a cell housing configured to accommodate the plurality of battery cells; a top plate configured to entirely cover an upper side of the cell housing and electrically connected to the negative electrode of each of the plurality of battery cells; a bottom plate disposed opposite the top plate to entirely cover a lower side of the cell housing and electrically connected to the positive electrode of each of the plurality of battery cells; and a phase change material filled in the cell housing such that the plurality of battery cells are partially submerged and cooling the plurality of battery cells, wherein a venting portion which is vented to lower an internal pressure of the battery cell when the internal pressure of the battery cell increases to a certain level or more is provided on a surface on which the positive electrode is formed, wherein a surface of the battery cell on which the venting portion is formed faces downward and thus the psoitive electrode is immersed in the liquefied phase change material.

The battery module may further include a heat sink mounted on an upper side of the top plate and configured to cool the plurality of battery cells.

The phase change material may be vaporized when a temperature of the plurality of battery cells rises to move toward the top plate, and may be liquefied by the heat sink to move toward the bottom plate.

The battery module may further include a guide rib provided on an upper side of an inner wall of the cell housing and configured to guide a movement of the liquefied phase change material toward the bottom plate.

The battery module may further include at least one cell fixing member configured to fix the plurality of battery cells so as to prevent movement of the plurality of battery cells in the cell housing.

The cell fixing member may be provided in a pair, and the pair of cell fixing members may include an upper cell fixing member into which upper portions of the plurality of battery cells are inserted and fixed to an upper side of an inner portion of the cell housing; and a lower cell fixing member into which lower portions of the plurality of battery cells are inserted and fixed to a lower side of the inner portion of the cell housing.

A plurality of cell insertion holes for insertion of the plurality of battery cells may be formed in the upper cell fixing member and the lower cell fixing member.

An edge of the top plate may be seamed with an edge of the cell housing.

In another aspect of the present disclosure, there is provided a battery pack including at least one battery module according to an embodiment as described above and a pack case configured to package the at least one battery module.

In another aspect of the present disclosure, there is provided a vehicle including at least one battery pack according to an embodiment as described above.

According to various embodiments as described above, provided may be a battery module having a structure capable of not only maximizing cooling performance but also effectively preventing a secondary event such as a thermal runaway phenomenon caused by a high temperature venting gas from occurring when the venting gas is discharged from the battery cell, a battery pack including the battery module, and a vehicle including the battery pack.

In addition, in order to help the understanding of the invention, the accompanying drawings are not shown in actual scale, but dimensions of some components may be exaggeratedly shown.

<FIG> is a view for explaining a battery module according to an embodiment of the present disclosure, <FIG> is an exploded perspective view of the battery module of <FIG>, <FIG> is a cross-sectional view of the battery module of <FIG>, <FIG> is a view for explaining coupling of a top plate and a cell housing of the battery module of <FIG>, <FIG> is a view for explaining an electrode connection of battery cells of the battery module of <FIG>, and <FIG> is a view for explaining a cooling principle of the battery module of <FIG>.

Referring to <FIG>, a battery module <NUM> includes a battery cell <NUM>, a cell housing <NUM>, at least one cell fixing members <NUM> and <NUM>, a heat sink <NUM>, a phase change material <NUM>, a top plate <NUM>, and a bottom plate <NUM>.

The battery cell <NUM> is provided in plurality, and the plurality of battery cells <NUM> are provided as a cylindrical secondary battery. The plurality of battery cells <NUM> are stacked and electrically connected to each other.

When the battery cell <NUM> is a cylindrical secondary battery, a positive electrode <NUM> is provided at a center portion of one side surface of the battery cell <NUM> in a longitudinal direction. A negative electrode <NUM> is provided at a center portion of the other side surface of the battery cell <NUM> in the longitudinal direction. A venting portion (not shown) which is vented to lower an internal pressure of the battery cell <NUM> to ensure safety when the internal pressure of the battery cell <NUM> increases to a certain level or more is provided on a surface on which the positive electrode <NUM> is formed.

The cell housing <NUM> accommodates the plurality of battery cells <NUM>. To this end, an accommodation space capable of accommodating the plurality of battery cells <NUM> is provided in the cell housing <NUM>.

A guide rib <NUM> may be provided inside the cell housing <NUM>.

The guide rib <NUM> may be provided on an upper side of an inner wall of the cell housing <NUM>, and may guide a movement of the phase change material <NUM> to a lower side when the phase change material <NUM> is liquefied L which will be described below. Specifically, the guide rib <NUM> may guide a faster movement of the phase change material <NUM> that is vaporized V and then liquefied L again as the internal temperature rises toward the bottom plate <NUM>, which will be described below.

The at least one cell fixing members <NUM> and <NUM> fix the plurality of battery cells <NUM> to prevent movement of the plurality of battery cells <NUM> in the cell housing <NUM>.

Such cell fixing members <NUM> and <NUM> are provided as a pair. The pair of cell fixing members <NUM> and <NUM> includes an upper cell fixing member <NUM> and a lower cell fixing member <NUM>.

The upper cell fixing member <NUM> into which upper portions of the plurality of battery cells <NUM> are inserted is fixed to the upper side of the inner portion of the cell housing <NUM>. To this end, a plurality of cell insertion holes <NUM> into which the upper portions of the plurality of battery cells <NUM> are inserted are formed in the upper cell fixing member <NUM>.

The lower cell fixing member <NUM> into which lower portions of the plurality of battery cells <NUM> are inserted is fixed to the upper side of the inner portion of the cell housing <NUM>. To this end, a plurality of cell insertion holes <NUM> into which the lower portions of the plurality of battery cells <NUM> are inserted are formed in the lower cell fixing member <NUM>.

The heat sink <NUM> is for cooling the plurality of battery cells <NUM>, and may be mounted on an upper side of the top plate <NUM> which will be described below. The heat sink <NUM> may be mounted on the cell housing <NUM> instead of the upper side of the top plate <NUM> which will be described below.

The phase change material <NUM> functions as an insulating oil for efficiently cooling the plurality of battery cells <NUM>, and may be partially filled in the cell housing <NUM>. Accordingly, the plurality of battery cells <NUM> may be partially submerged in the phase change material <NUM> within the cell housing <NUM>.

The phase change material <NUM> may be vaporized V when the temperature of the plurality of battery cells <NUM> rises to move toward the top plate <NUM> which will be described below, and may be liquefied L by the heat sink <NUM> to move toward the bottom plate <NUM> which will be described below. Such vaporization V and liquefaction L may be cyclically repeated, and through this, cooling of the battery cells <NUM> may be more effectively performed.

The phase change material <NUM> may be made of a fluorine-based material having a low boiling point for more effective circulation. For example, the phase change material <NUM> may include a material having a boiling point of between <NUM> degrees and <NUM> degrees. In addition, the phase change material <NUM> may include a material having an extinguishment function. Accordingly, when a fire occurs in the battery module <NUM>, it is possible to quickly extinguish the fire through the phase change material <NUM>.

The top plate <NUM> may be coupled to the cell housing <NUM> so as to entirely cover the upper side of the cell housing <NUM>. Here, the top plate <NUM> may be coupled to the cell housing <NUM> through a seaming structure. This is to maximize an airtight structure of the cell housing <NUM>, and to prevent evaporation of the phase change material <NUM> in the cell housing <NUM>. The seaming structure may be formed in an edge of the top plate <NUM> and an upper edge of the cell housing <NUM>. That is, the edge of the top plate <NUM> may be seamed with the upper edge of the cell housing <NUM>.

The top plate <NUM> is electrically connected to the negative electrode <NUM> of the plurality of battery cells <NUM>. To this end, the top plate <NUM> is made of a metal material, and may be welded to the negative electrode <NUM> of the plurality of battery cells <NUM>. That is, in the present embodiment, the top plate <NUM> functions not only as a cover for sealing the cell housing <NUM>, but also as a bus bar for the electrical connection of the battery cells <NUM>.

Accordingly, in the present embodiment, since both of these functions may be implemented through the top plate <NUM>, a separate bus bar structure for the electrical connection between the negative electrodes <NUM> of the battery cells <NUM> is not required.

Meanwhile, for insulation between the top plate <NUM> and the cell housing <NUM>, the top plate <NUM> may be insulated in a coupling portion with the cell housing <NUM>. In the present embodiment, the top plate <NUM> may be insulated in a seamed edge part and then insulated from the cell housing <NUM>. If the cell housing <NUM> includes a non-metal material instead of a metal material, such insulation may be omitted.

The bottom plate <NUM> is disposed opposite to the top plate <NUM> to entirely cover the lower side of the cell housing <NUM>. Such a bottom plate <NUM> may be integrally formed with the cell housing <NUM> or may be separately provided and mounted on a bottom portion of the cell housing <NUM>.

Such a bottom plate <NUM> is electrically connected to the positive electrodes <NUM> of the plurality of battery cells <NUM>. As such, the bottom plate <NUM> functions as not only a cover for sealing the bottom portion of the cell housing <NUM>, but also a bus bar for the electrical connection of the battery cells <NUM> together with the top plate <NUM>.

To this end, the bottom plate <NUM> is made of a metal material, and may be welded and coupled to the positive electrodes <NUM> of the plurality of battery cells <NUM>. Meanwhile, when the bottom plate <NUM> is integrally formed with the cell housing <NUM>, the cell housing <NUM> may also be made of a metal material. In this case, for insulation from the top plate <NUM>, as described above, the cell housing <NUM> may be insulated from the top plate <NUM> in a coupling portion. If the bottom plate <NUM> has a structure in which the cell housing <NUM> is separately mounted, the cell housing <NUM> may be made of a non-metal material, and in this case, the insulation may be omitted.

Accordingly, in the present embodiment, both the sealing of the cell housing <NUM> and the electrical connection of the positive electrodes <NUM> of the battery cells <NUM> is implemented through the bottom plate <NUM>, and thus a separate bus bar structure for the connection of the positive electrodes <NUM> of the battery cells <NUM> is not required.

As such, in the present embodiment, since the top plate <NUM> and the bottom plate <NUM> for sealing the cell housing <NUM> also implement a bus bar function for the electrical connection of the electrodes <NUM> and <NUM> of the battery cells <NUM>, a separate additional bus bar structure may be omitted, thereby reducing the manufacturing cost of the battery module <NUM> and improving manufacturing efficiency.

Meanwhile, in the present disclosure, the battery cell <NUM> is disposed upright in the cell housing <NUM> such that the positive electrode <NUM> faces downward and the negative electrode <NUM> faces upward. That is, as described above, the battery cell <NUM> is disposed to have directionality such that the positive electrode <NUM> is in face-to-face contact with the bottom plate <NUM> and the negative electrode <NUM> is in face-to-face contact with the top plate <NUM>.

In the case of a cylindrical battery cell, the positive electrode <NUM> and the negative electrode <NUM> are respectively formed on both side surfaces in the longitudinal direction, and a venting portion, which is designed to be weak in terms of rigidity in comparison with a surrounding region and is preferentially broken when the internal pressure of the battery cell <NUM> increases so that gas generated inside the battery cell <NUM> may be discharged, is formed in the surface on which the positive electrode <NUM> is formed.

The battery module <NUM> according to the present disclosure has a structure in which the surface on which the venting portion is formed, that is, the surface on which the positive electrode <NUM> is formed, faces downward, and thus the positive electrode <NUM> is immersed in the liquefied phase change material <NUM>. Therefore, the battery module <NUM> according to an embodiment of the present disclosure may prevent the temperature inside the battery module <NUM> from rapidly increasing when a high temperature venting gas is ejected due to an increase in the internal pressure of the battery cell <NUM>, thereby preventing the occurrence of a secondary event due to a gas ejection, and securing safety in using the secondary battery.

In addition, the battery module <NUM> according to the present embodiment further secures the capacity of the battery cells <NUM> by the volume of a separate additional bus bar structure which is omitted even in terms of energy density. In addition, the battery module <NUM> according to the present embodiment may also maximize cooling performance through the phase change material <NUM>.

Next, a battery module according to another embodiment of the present disclosure will be described with reference to <FIG>. The battery module according to another embodiment of the present disclosure is merely different from the battery module according to the previous embodiment in that a contact protrusion <NUM> is formed on the bottom plate <NUM>, and other components are substantially the same. Therefore, in describing the battery module according to another embodiment of the present disclosure, descriptions redundant with those of the previous embodiment will be omitted, and only the differences will be mainly described.

The contact protrusion <NUM> is formed to protrude upward from the bottom plate <NUM>. The contact protrusion <NUM> is formed at a position corresponding to the positive electrode <NUM> of the battery cell <NUM> and is in contact with the positive electrode <NUM>. The contact protrusion <NUM> is provided as many as the number of battery cells <NUM>.

The contact protrusion <NUM> is used to separate between one surface of the battery cell <NUM> on which the positive electrode <NUM> is formed in the cell insertion hole <NUM> formed in the lower cell fixing member <NUM> and the bottom plate <NUM>, which provides a space in which the liquefied phase change material <NUM> is filled. The contact protrusion <NUM> is made of a conductive material for electrical connection of the plurality of battery cells <NUM>.

As such, when a space is formed between the positive electrode <NUM> and the bottom plate <NUM> in the cell insertion hole <NUM> formed in the lower cell fixing member <NUM>, and the phase change material <NUM> is filled therein, upon venting of the battery cell <NUM>, effective cooling is possible and the occurrence of a secondary event such as ignition by a high temperature gas may be effectively prevented.

Next, a battery module according to another embodiment of the present disclosure will be described with reference to <FIG>. The battery module according to another embodiment of the present disclosure is merely different from the battery module shown in <FIG> in that a flow path P through which the liquefied phase change material <NUM> may move is formed in the lower cell fixing member <NUM>, and other components are substantially the same. Accordingly, in describing the battery module according to another embodiment of the present disclosure, the flow path P will be mainly described, and descriptions redundant with those of the previous embodiments will be omitted.

The flow path P is formed in the lower cell fixing member <NUM>, and penetrates between an upper surface of the lower cell fixing member <NUM> and an inner side surface of the cell insertion hole <NUM> formed in the lower cell fixing member <NUM>. The liquefied phase change material <NUM> may be smoothly introduced into a space between the positive electrode <NUM> and the bottom plate <NUM> through the flow path P.

<FIG> is a view for explaining a battery pack according to an embodiment of the present disclosure.

Referring to <FIG>, a battery pack <NUM> may include the at least one battery module <NUM> according to the previous embodiment and a pack case <NUM> packaging the at least one battery module <NUM>.

Such a battery pack <NUM> may be provided in a vehicle, as a fuel source of the vehicle. As an example, the battery pack <NUM> may be provided in an electric vehicle, a hybrid vehicle, and the vehicle in other methods of using the other battery pack <NUM> as a fuel source. In addition, the battery pack <NUM> may be provided in other devices such as an energy storage system that uses a secondary battery, instruments, and facilities, in addition to the vehicle.

As such, the vehicle according to the present embodiment and devices such as the vehicle, instruments, and facilities including the battery pack <NUM> include the battery module <NUM> described above, and thus the battery pack <NUM> having all the advantages owing to the battery module <NUM> described above and devices such as the vehicle, instruments, and facilities including such a battery pack <NUM> may be implemented.

Claim 1:
A battery module (<NUM>) comprising:
a plurality of cylindrical battery cells (<NUM>) disposed upright such that a positive electrode (<NUM>) faces downward and a negative electrode (<NUM>) faces upward;
a cell housing (<NUM>) configured to accommodate the plurality of battery cells (<NUM>);
a top plate (<NUM>) configured to entirely cover an upper side of the cell housing (<NUM>) and electrically connected to the negative electrode (<NUM>) of each of the plurality of battery cells (<NUM>);
a bottom plate (<NUM>) disposed opposite the top plate (<NUM>) to entirely cover a lower side of the cell housing (<NUM>) and electrically connected to the positive electrode (<NUM>) of each of the plurality of battery cells (<NUM>); and
a phase change material (<NUM>) filled in the cell housing (<NUM>) such that the plurality of battery cells (<NUM>) are partially submerged, and cooling the plurality of battery cells (<NUM>),
characterized in that a venting portion which is vented to lower an internal pressure of the battery cell (<NUM>) when the internal pressure of the battery cell (<NUM>) increases to a certain level or more is provided on a surface on which the positive electrode (<NUM>) is formed,
wherein a surface of the battery cell (<NUM>) on which the venting portion is formed faces downward and thus the positive electrode (<NUM>) is immersed in the liquefied phase change material (<NUM>).