Patent Description:
Currently, the performance of a secondary battery is rapidly reduced under a certain temperature. This may make a problem when a vehicle employing the secondary battery such as a HEV, a PHEV and a BEV is used in countries where winter exists or which are relatively close to the polar region.

That is, when the temperature is low, if the temperature of the vehicle parked overnight decreases, the temperature of the secondary battery inside the vehicle also decreases, and thus the vehicle may not be easily started in the next morning. In addition, even when the vehicle is running, the low temperature greatly affects the life and performance of the battery.

It is possible to heat the secondary battery in advance by using a heater or the like before the vehicle is started. However, since the power supplied to the heater is also provided through the secondary battery, in a low temperature environment where the performance of the secondary battery is deteriorated, there is still the problem of the deteriorated performance of the secondary battery.

<CIT>, <CIT> and <CIT> describe battery module and phase change heater.

The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to deriving the normal performance of a battery pack by quickly preheating the battery pack in advance through very low power consumption before a vehicle is used.

The invention is defined in the pending set of claims. According to claim <NUM>, the invention is a battery module, comprising: a cell stack having a plurality of battery cells; and a phase change preheater disposed on the cell stack and containing a phase change material that causes a phase change as crystal nucleus is formed and accordingly causes an exothermic reaction.

The phase change material may include at least one solution selected from a sodium hydroxide supersaturated solution, a sodium acetate supersaturated solution and a sodium thiosulfate supersaturated solution.

The phase change preheater may include a pouch placed on the cell stack; the phase change material contained in the pouch; a first driving unit located in the pouch; a first friction plate attached to the first driving unit; and a second friction plate configured to form metal crystal nucleus by causing a friction with the first friction plate as the first driving unit is driven.

The phase change preheater may further include a connector located out of the pouch and electrically connected to the first driving unit.

The phase change preheater may further include a support frame provided through the pouch and configured to fix the first driving unit and the second friction plate.

The phase change preheater may include a pouch; the phase change material contained in the pouch; a first driving unit located in the pouch; a first friction plate attached to the first driving unit; a second driving unit located in the pouch; and a second friction plate attached to the second driving unit and configured to form metal crystal nucleus by causing a friction with the first friction plate as the first driving unit and the second driving unit are driven.

The phase change preheater may further include a connector located out of the pouch and electrically connected to the first driving unit and the second driving unit.

The phase change preheater may further include a support frame provided through the pouch and configured to fix the first driving unit and the second driving unit.

The battery module further comprises a film heater disposed on the phase change preheater and connected to an external power source to heat the phase change preheater so that the phase change material phase-changed into a solid state is phase-changed into a liquid state again.

The battery module may further comprise a pair of bus bar frame assemblies including a pair of bus bar frames configured to cover one longitudinal end and the other longitudinal end of the cell stack and a plurality of bus bars fixed onto the bus bar frames and electrically connected to the battery cells.

The battery module may further comprise a module case configured to cover peripheries of the cell stack and the phase change preheater in a state where the bus bar frame assembly is exposed out.

The battery module may further comprise a pair of end plates configured to cover the bus bar frame assembly.

In another aspect of the present disclosure, there is also provided a battery pack, which comprises the battery module according to an embodiment the present disclosure as described above.

In another aspect of the present disclosure, there is also provided a vehicle, which comprises the battery module according to an embodiment the present disclosure as described above.

According to an embodiment of the present disclosure, it is possible to quickly preheat a battery pack in advance through very low power consumption before a vehicle is used, thereby deriving the normal performance of the battery pack mounted to a vehicle.

Referring to <FIG>, a battery module according to an embodiment of the present disclosure includes a cell stack <NUM>, a bus bar frame assembly <NUM>, an outer terminal <NUM>, a phase change preheater <NUM>, a module case <NUM> and an end plate <NUM>.

As shown in <FIG>, the cell stack <NUM> includes a plurality of battery cells <NUM> stacked such that their wide surfaces face each other. The cell stack <NUM> may include at least one buffer pad P interposed between an outermost battery cell <NUM> and/or neighboring battery cells <NUM>.

That is, the cell stack <NUM> may be inserted into the module case <NUM> in a state of being coupled with the bus bar frame assembly <NUM>, the outer terminal <NUM> and the phase change preheater <NUM>. At this time, the buffer pad P made of an elastic material such as a sponge may be additionally applied so that the cell stack <NUM> has a maximized volume and is easily inserted.

A pouch-type battery cell may be applied as the battery cell <NUM>. The pouch-type battery cell <NUM> includes a pair of electrode leads <NUM> that are respectively drawn at both longitudinal sides.

Referring to <FIG>, the bus bar frame assembly <NUM> may include a bus bar frame <NUM> configured to cover one longitudinal side and the other longitudinal side of the cell stack <NUM> and a plurality of bus bars <NUM> fixed onto the bus bar frame <NUM> and electrically connected to the battery cell <NUM>.

The bus bar frame <NUM>, for example, may be made of a material with an insulating property such as resin. The bus bar frame <NUM> and the bus bar <NUM> have slits formed at positions corresponding to each other so that the electrode lead <NUM> may be drawn out. The electrode lead <NUM> drawn out through the slit is bent to come into close contact with the bus bar <NUM> and fixed to the bus bar <NUM> by welding or the like.

The outer terminal <NUM> is fixed onto the bus bar frame <NUM> and is connected to the electrode lead <NUM> located at both outermost sides of the cell stack <NUM> in a width direction (an X-axis direction in <FIG>).

Referring to <FIG> and <FIG>, the phase change preheater <NUM> is disposed at an upper portion of the cell stack <NUM> (an upper side along the Z-axis direction in <FIG>) and contains a phase change material that causes a phase change as crystal nucleus is formed and accordingly causes an exothermic reaction.

The phase change preheater <NUM> prevents the performance of the battery module from deteriorating due to a low temperature by preheating the cell stack <NUM> disposed therebelow by means of the exothermic reaction according to the phase change.

More specifically, the phase change preheater <NUM> includes a pouch <NUM>, a phase change material M, a support frame <NUM>, a first driving unit <NUM>, a first friction plate <NUM>, a second friction plate <NUM>, a connection line <NUM> and a connector <NUM>.

The pouch <NUM> accommodates the phase change material M therein and is placed on the cell stack <NUM> to directly contact the cell stack <NUM>. More specifically, the pouch <NUM> is in direct contact with the side portion of each battery cell <NUM> of the cell stack <NUM>.

The phase change material M is a material that exists in a supersaturated solution state and causes a phase change into a solid phase by crystallization when crystal nucleus is provided by a physical impact. The phase change process causes an exothermic reaction, and the heat generated according to the exothermic reaction is conducted through the pouch <NUM> and used to preheat the cell stack <NUM> disposed below the phase change preheater <NUM>.

As the phase change material M, for example, a supersaturated solution including at least one of a sodium hydroxide supersaturated solution, a sodium acetate supersaturated solution and a sodium thiosulfate supersaturated solution may be used. As explained later, if fine metal particles are provided into the supersaturated solution by a physical impact, the supersaturated solution is crystallized using the metal particles as crystal nucleus, and as a result crystals are generated so that the supersaturated solution in the pouch is phase-changed into a solid state.

In addition, if the supersaturated solution phase-changed into a solid phase is heated to a temperature of about <NUM> or higher, the supersaturated solution is phase-changed again into a liquid state by an endothermic reaction, and in this state, the cell stack <NUM> may be preheated. The battery module according to an embodiment of the present disclosure may be used in a vehicle such as a HEV, a PHEV and a BEV, and the energy required to phase-change the phase change preheater <NUM> into an original state again after the exothermic reaction is completed may be obtained using the heat generated by using the battery module while the vehicle is running. In addition, if the vehicle travels a relatively short distance and thus the heat required for completing the exothermic reaction so that the phase change preheater <NUM> phase-changed into a solid state is phase-changed again into an original state is sufficiently obtained, an additional heat source is required. This will be described later in detail while explaining a battery module according to another embodiment of the present disclosure.

The support frame <NUM> penetrates the pouch <NUM> partially, and accordingly the support frame <NUM> is partially located inside the pouch <NUM> and partially located out of the pouch <NUM>. The support frame <NUM> includes a first support frame <NUM> and a second support frame <NUM>, which are formed by dividing one end of the support frame into two parts. The first support frame <NUM> and the second support frame <NUM> are located inside the pouch <NUM>.

The first driving unit <NUM> is fixed to an end of the first support frame <NUM>. The first driving unit <NUM> may be a motor. The first friction plate <NUM> may be attached to the first driving unit <NUM> to rotate as the first driving unit <NUM> is driven.

The second friction plate <NUM> is fixed to an end of the second support frame <NUM> to come into surface contact with the first friction plate <NUM>. Thus, as the first driving unit <NUM> is driven, the contact surfaces of the first friction plate <NUM> and the second friction plate <NUM> may cause friction with each other to form fine metal particles. That is, both the first friction plate <NUM> and the second friction plate <NUM> are made of a metal material, and the fine metal particles formed as above act as metal crystal nucleus to cause a phase change.

Meanwhile, referring to <FIG>, unlike <FIG>, the second friction plate <NUM> is not fixed to the second support frame <NUM> but is attached to a second driving unit <NUM> that is fixed to the second support frame <NUM>. Similar to the first driving unit <NUM>, the second driving unit <NUM> may also be a motor. If both the first friction plate <NUM> and the second friction plate <NUM> cause friction in a rotating manner as described above, metal crystal nucleus may be formed more easily, and thus an exothermic reaction according to the phase change may be more quickly derived.

Referring to <FIG> again, the connection line <NUM> electrically connects the first driving unit <NUM> and the second driving unit <NUM> located inside the pouch <NUM> to the connector <NUM> located out of the pouch <NUM>. The connection line <NUM> may extend through the support frame <NUM>.

The connector <NUM> is a component for connection to a power source for supplying power to the first driving unit <NUM> and the second driving unit <NUM>, and may be, for example, connected onto a circuit line along which current flows while the vehicle is in a key-on state. In this case, when a user keys on to start the vehicle, the first driving unit <NUM> and the second driving unit <NUM> may be driven by power supplied through the battery module according to an embodiment of the present disclosure or another battery separately installed to generate metal crystal nucleus, and thus the battery module may be preheated. The exothermic reaction using the crystallization is not performed by an external physical impact but is performed only when the metal therein generates crystal nucleus. The metal crystal nucleus may be generated even with very small energy, and thus the power consumed therefor is not large, efficiently.

Referring to <FIG> together again, the module case <NUM> covers peripheries of the cell stack <NUM> and the phase change preheater <NUM> in a state where the bus bar frame assembly <NUM> is exposed out.

The end plate <NUM> is provided in a pair, and each end plate <NUM> covers the bus bar frame assembly <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 further includes a film heater <NUM>, compared to the battery module according to the former embodiment of the present disclosure described above, and other components are substantially not different.

Thus, the battery module according to another embodiment of the present disclosure will be described based on the film heater <NUM>, and other features identical to the former embodiment will not be described in detail.

Referring to <FIG>, the film heater <NUM> includes a film <NUM> disposed on the phase change preheater <NUM> to cover the phase change preheater <NUM> and a heat wire <NUM> embedded in the film <NUM>. The film heater <NUM> is connected to an external power source to heat the phase change preheater <NUM>. That is, the film heater <NUM> heats the phase change preheater <NUM> to a certain temperature or higher (approximately <NUM> or higher) to phase-change the phase change preheater <NUM> from a liquid phase into a solid phase and to phase-change the phase change preheater <NUM> into a liquid phase again after the exothermic reaction is completed.

Since the battery module is in use while the vehicle is running, sufficient heat is normally generated, so the phase change preheater <NUM>, which has phase-changed from a liquid phase into a solid phase before the vehicle starts, is phase-changed again into a liquid phase while the vehicle is running. However, if the vehicle travels an insufficient distance or repeats running and starting-off at short intervals, the temperature of the battery module may not rise sufficiently, so that the phase change preheater <NUM> may be kept in a solid state without being phase-changed into a liquid state.

Therefore, when the vehicle, namely the battery module, is charged, the film heater <NUM> may be connected to a charger and driven with the power supplied therefrom to heat the phase change preheater <NUM> so that the temperature of the phase change material M inside the phase change preheater <NUM> rises to about <NUM> or higher. If the temperature rises as above, the phase change preheater <NUM> may be phase-changed again into a liquid phase, and thus it is ready to preheat the battery module.

Claim 1:
A battery module, comprising:
a cell stack (<NUM>) having a plurality of battery cells (<NUM>); and
a phase change preheater (<NUM>) disposed on the cell stack (<NUM>) and containing a phase change material that causes a phase change as crystal nucleus is formed and accordingly causes an exothermic reaction,
a film heater (<NUM>) disposed on the phase change preheater (<NUM>) and connected to an external power source to heat the phase change preheater (<NUM>) so that the phase change material phase-changed into a solid state is phase-changed into a liquid state again.