Patent ID: 12237516

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, structures of a case for a secondary battery and the secondary battery according to the present invention will be described with reference to the accompanying drawings.

Case for Secondary Battery and Secondary Battery

FIG.2is a plan view illustrating a state in which a case for a secondary battery is unfolded according to the present invention, andFIG.3is a vertical cross-sectional view illustrating a state in which the case for the secondary battery is unfolded according to an embodiment of the present invention.

In the present specification, ‘the state when the case is unfolded’ may mean a state of the case when the case is unfolded by releasing predetermined bonding existing in the case, but is left without applying artificial force to the case.

A case10for a secondary battery (hereinafter, referred to as a ‘case’) according to the present invention may be configured to accommodate an electrode assembly having a structure in which electrodes and separators are alternately disposed.

Here, as illustrated inFIGS.2and3, the case10may include a recess part100having a recessed shape. The recess part100may include a first recess part110and a second recess part120provided at one side of the first recess part110.

As described above, the recess part100may have a recessed shape. Therefore, an internal space of the recess part may be defined in the recess part100. That is, as illustrated inFIGS.2and3, the case10may have a recessed space A1defined by the first recess part110and a recessed space A2defined by the second recess part120.

According to the present invention, the case10may further include a circumferential part300surrounding circumferences of the first recess part110and the second recess part120when the case10is unfolded.

In this case, the circumferential part300may include a first circumferential part310disposed around the first recess part110and a second circumferential part320disposed around the second recess part120. As illustrated inFIGS.2and3, the first circumferential part310and the second circumferential part320may be in contact with each other.

Also, the case10according to the present invention may further include a connection part150connecting the first recess part110to the second recess part120. As illustrated inFIGS.2and3, the connection part150may be provided between the first recess part110and the second recess part120. As illustrated inFIG.3, the connection part150may be opened with respect to the first recess part110and the second recess part120. Thus, the recessed space A1of the first recess part110and the recessed space A2of the second recess part120may communicate with each other by the connection part150.

According to the present invention, when the case10is unfolded, the case10may be bent in a V shape on an area on which the first circumferential part310and the second circumferential part320meet each other. InFIG.3, the V-shaped bent part200is illustrated on the area on which the first circumference310and the second circumferential part320meet each other. Thus, as illustrated inFIG.3, when the case10is unfolded, the recessed space A1defined by the first recess part110and the recessed space A2defined by the second recess part120may face each other.

According to the related art, in order to manufacture a pouch type secondary battery, a process of folding a sheet-type exterior after pressing a portion of an area of the sheet-type exterior having a flat shape to form a recess part in the sheet-type exterior is performed.

However, according to the related art, before being folded, since the sheet-type exterior has the flat shape except for the area, in which the recess part is defined, with respect to the area to be folded, it is necessary to fold the sheet-type exterior at 180 degrees. However, in this case, since the folding angle of the sheet-type exterior is large, deformation in shape of the sheet-type exterior may increase before and after the folding process. Thus, a dead space that is not contributed to improve capacity in the secondary battery may be generated to cause a problem in which an outer appearance of the sheet-type exterior is largely deformed.

However, according to the present invention, since the area on which the sheet-type exterior (i.e., the case) is folded has the V-shape, the folding angle of the sheet-type exterior decreases in the folding process according to the related art. Thus, the deformation in shape of the sheet-type exterior before and after the folding process may be minimized. Thus, the dead space that is not distributed to improve the capacity in the secondary battery may be reduced to minimize the deformation in outer appearance, which occurs in the sheet-type exterior.

FIG.4is an enlarged vertical cross-sectional view illustrating a state in which a first recess part, a second recess part, and a connection part are connected in a case for a secondary battery according to a first embodiment of the present invention, andFIG.5is an enlarged vertical cross-sectional view illustrating a state in which a first recess part, a second recess part, and a connection part are connected in a case for a secondary battery according to a second embodiment of the present invention. Also,FIG.6is an enlarged vertical cross-sectional view illustrating a state in which a first recess part, a second recess part, and a connection part are connected in a case for a secondary battery according to a third embodiment of the present invention.

As described above, since the recess part100has the recessed shape, the first recess part110and the second recess part120, which constitute the recess part100, may be recessed by a predetermined thickness from the first circumferential part310and the second circumferential part320, respectively.FIGS.4to6illustrate a state in which the first recess part110is recessed by a predetermined thickness W1from the first circumferential part310, and the second recess part120is recessed by a predetermined thickness W2from the second circumferential part320.

When the case10is unfolded, the first recess part110and the second recess part120have shapes that are symmetrical to each other with respect to the connection part150. Thus, referring toFIGS.4to6, the thickness W1by which the first recess part110is recessed from the first circumferential part310may be the same as the thickness W2by which the second recess part120is recessed from the second circumferential part320. However, unlike this, the first recess part110and the second recess part120may have shapes that are asymmetrical to each other. Thus, the thickness W1by which the first recess part110is recessed from the first circumferential part310may be different from the thickness W2by which the second recess part120is recessed from the second circumferential part320.

As illustrated inFIGS.3to6, according to an embodiment of the present invention, when the case10is unfolded, the connection part150of the case10may have a shape that is recessed from the first recess part110and the second recess part120in one direction. For example, as illustrated inFIGS.3to6, the connection part150may be recessed downward from the first recess part110and the second recess part120. Thus, a stepped portion may be provided on each of an area on which the first recess part110and the connection part150are connected to each other and an area on which the second recess part120and the connection part150are connected to each other.

Here, referring toFIG.4, according to a first embodiment of the present invention, when the case10is unfolded, each of the thickness W1by which the first recess part110is recessed from the first circumferential part310and the thickness W2by which the second recess part120is recessed from the second circumferential part320may be less than a thickness W3by which the connection part150is recessed from each of the first recess part110and the second recess part120. Also, according to the first embodiment of the present invention, when the case10is unfolded, an end of a lower portion of a bent part200, which is provided as the first circumferential part310and the second circumferential part320meet each other, may be disposed below an end of each of a lower portion of the first recess part110and a lower portion of the second recess part120.

Alternatively, referring toFIG.5, according to a second embodiment of the present invention, when the case10is unfolded, each of the thickness W1by which the first recess part110is recessed from the first circumferential part310and the thickness W2by which the second recess part120is recessed from the second circumferential part320may be the same as the thickness W3by which the connection part150is recessed from each of the first recess part110and the second recess part120. Also, according to the second embodiment of the present invention, when the case10is unfolded, an end of a lower portion of a bent part200, which is provided as the first circumferential part310and the second circumferential part320meet each other, may be disposed at the same height as an end of each of a lower portion of the first recess part110and a lower portion of the second recess part120.

Alternatively, referring toFIG.6, according to a third embodiment of the present invention, when the case10is unfolded, each of the thickness W1by which the first recess part110is recessed from the first circumferential part310and the thickness W2by which the second recess part120is recessed from the second circumferential part320may be greater than a thickness W3by which the connection part150is recessed from each of the first recess part110and the second recess part120. Also, according to the third embodiment of the present invention, when the case10is unfolded, an end of a lower portion of a bent part200, which is provided as the first circumferential part310and the second circumferential part320meet each other, may be disposed above an end of each of a lower portion of the first recess part110and a lower portion of the second recess part120.

FIG.7is a vertical cross-sectional view illustrating a state in which a case for a secondary battery is unfolded according to another embodiment of the present invention, andFIG.8is an enlarged vertical cross-sectional view illustrating a state in which a first recess part, a second recess part, and a connection part are connected in a case for a secondary battery according to a fourth embodiment of the present invention. Hereinafter, differences from the above-described contents with respect to the case for the secondary battery according to an embodiment of the present invention or the first to third embodiments of the present invention will be mainly described.

As illustrated inFIGS.7and8, according to another embodiment of the present invention, when a case10is unfolded, a connection part150may connect a first recess part110to a second recess part120so as to be flat. Thus, a stepped portion may not be provided on each of an area on which the first recess part110and the connection part150are connected to each other and an area on which the second recess part120and the connection part150are connected to each other. Here, as illustrated inFIG.8, when the case10is unfolded, an area Z1on which the first recess part110and the connection part150are connected to each other and an area Z2on which the second recess part120and the connection part150are connected to each other may be provided as a smooth curved surface.

The above-described contents with respect to the case for the secondary battery according to an embodiment of the present invention or the first to third embodiments of the present invention may be applied as it is to the case according to the fourth embodiment within a range that is not inconsistent with the above-described contents with respect to the case according to another embodiment of the present invention or the fourth embodiment of the present invention.

FIG.9is a perspective view illustrating a state in which an electrode assembly is accommodated in the case for the secondary battery according to the present invention. As illustrated inFIG.9, a first recess part110(seeFIG.3) and a second recess part120(seeFIG.3) accommodate an electrode assembly20in a state in which a case according to the present invention is unfolded. Thereafter, an area, on which the first recess part and a first circumferential part are disposed, and an area, on which the second recess part and a second circumferential part are disposed are identified. Then, the first circumferential part and the second circumferential part may be attached to each other to manufacture a secondary battery.

Here, as illustrated inFIG.9, the sum of thicknesses of the first recess part and the second recess part of the case10may correspond to a thickness of an electrode assembly. This is because the electrode assembly is accommodated in a space defined by the first recess part and the second recess part.

Thus, referring toFIGS.4to6and8, the sum of a thickness W1by which the first recess part110is recessed from the first circumferential part310and a thickness W2by which the second recess part120is recessed from the second circumferential part320may correspond to a width W4of a connection part150. For example, the sum of the thickness W1by which the first recess part110is recessed from the first circumferential part310and the thickness W2by which the second recess part120is recessed from the second circumferential part320may be the same as the width W4of the connection part150. In this case, when the secondary battery is manufactured using the case10according to the present invention, since the width of the internal space defined in the case is constant, the electrode assembly manufactured to have a predetermined width may be stably accommodated. However, unlike this, the sum of the thickness W1by which the first recess part110is recessed from the first circumferential part310and the thickness W2by which the second recess part120is recessed from the second circumferential part320may be less or greater than the width W4of the connection part150.

Referring again toFIG.3, when the case10is unfolded, the case10according to the present invention may have a V shape on an area on which the first circumferential part310and the second circumferential part320meet each other. Thus, a bent part200may be provided on the area on which the first circumferential part310and the second circumferential part320meet each other, and the bent part200may have a predetermined angle.FIG.3, the angle of the bent part200is illustrated by θ. The angle θ may have a value ranging of 80 degrees to 160 degrees.

In addition, as illustrated inFIG.3, a predetermined angle α may be defined at an area, on which an inner surface disposed at an opposite side of the connection part150among inner surfaces of the first recess part110and the first circumferential part310meet each other. Here, the angle α may be an obtuse angle.

Here, the following Equation 1 may be satisfied between the angle θ and the angle α.
θ+2α=360°  [Equation 1]

FIG.10is a cross-sectional view illustrating a geometrical relationship between the first recess part and the connection part ofFIG.3.

Equation 1 may be a formula that is established because of a process of manufacturing the case10according to the present invention.

That is, the case10according to the present invention may be manufactured by bending the sheet-shaped exterior into a V shape and then pressing the sheet-shaped exterior downwardly perpendicular to the ground to form the recess part.

Thus, when (i) a thickness of the first recess part is constant, (ii) the first recess part and the connection part are formed by being pressed downward perpendicular to the ground, and (iii) the first recess part and the second recess part are symmetrical to each other, as illustrated inFIG.10, θ/2 and 180°−α may be the same, and thus, Equation 1 may be derived.

The secondary battery according to the present invention may include the electrode assembly having the structure, in which the electrodes and the separators are alternately disposed, and the case. The contents of the case are substituted with the contents described above.

While the embodiments of the present invention have been described with reference to the specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.