Unit Cell and Method and Apparatus for Manufacturing A Unit Cell

An apparatus for manufacturing a unit cell cuts lower and upper separators between sets of adjacent electrodes. In a state of a process of manufacturing the unit cell, the lower and upper separators continuously move in a longitudinal direction; and the electrodes are stacked between the separators and on the upper separator, respectively. The apparatus includes a lower block disposed under the lower separator and an upper block vertically aligned with the lower block above the upper separator. A lower end of a cutter is installed for access to the inside and outside. The upper block descends to press the separators to a surface of the lower block. One or both of the upper and lower blocks is heated to a predetermined temperature to thermally fuse pressed points of the separators. The cutter protrudes from the upper block to perform cutting at points at which the separators are pressed.

TECHNICAL FIELD

The present invention relates to a method and apparatus for manufacturing a unit cell and a unit cell manufactured by the manufacturing apparatus, and more particularly, to a method and apparatus for manufacturing a unit cell, in which cutting is performed in a state in which bonding (sealing) between a lower separator and an upper separator is performed, or boding and cutting are performed at the same time to prevent the separator from being folded, and a unit cell.

BACKGROUND

Recently, many studies on secondary batteries are being carried out because the secondary batteries are rechargeable unlike primarily batteries, and also, the possibility of compact size and high capacity is high. As technology development and demands for mobile devices increase, the demands for secondary batteries as energy sources are rapidly increasing.

Such a secondary battery is configured so that an electrode assembly and an electrolyte are embedded in a case (for example, a pouch, a can, and the like). The electrode assembly mounted in the case is repeatedly chargeable and dischargeable because of a structure in which a positive electrode/a separator/a negative electrode are stacked. The electrode assembly is manufactured in various manners. However, generally, the electrode assembly may be manufactured in a manner in which, after a unit cell4is prepared in advance, a plurality of unit cells4are stacked to manufacture the electrode assembly.

That is, referring toFIG.1a, which illustrates a state in which a unit cell is manufactured according to the related art, in a method for manufacturing the unit cell4according to the related art, a positive electrode1, an upper separator3a, a negative electrode2, and a lower separator3are continuously wound to be supplied in a state in which each of the positive electrode1, the upper separator3a, the negative electrode2, and the lower separator3bis wound in the form of a roll (however, stacking positions of the positive electrode and the negative electrode may be changed).

Here, the separators3(3aand3b) are continuously supplied without disconnection, the negative electrode2is supplied between the upper separator3aand the lower separator3b, and the positive electrode1is supplied onto the upper separator3a.

Here, the separators3are continuously supplied without being cut. On the other hand, the positive electrode1and the negative electrode2are provided in a state of being cut to predetermined sizes by respective cutters6and7, respectively. The positive electrode1and the negative electrode2are paired and stacked vertically with the upper separator3atherebetween and are disposed to be spaced a predetermined distance from the positive electrode1and the negative electrode2, which are paired to be adjacent to each other.

That is, the separators3are continuously connected, and the negative electrode2and the positive electrode1pass through a laminating device9in a state of being spaced a predetermined distance from the negative electrode2and the positive electrode1. In the laminating device9, heat and a pressure are applied so that the negative electrode2and the positive electrode1are bended to contact points with the separators3.

After the positive electrode1and the negative electrode2pass through the laminating device9in the state in which the positive electrode1and the negative electrode2are bonded to the separators3, the separators3are cut to be provided as individual unit cells between the positive electrode1and the positive electrode1, which are adjacent to each other.

That is, as illustrated inFIG.1b, which illustrates a shape of a cutter, which cuts the separators, according to the related art, after the laminating (bonding) of the electrodes1and2and the separators3due to the heat and pressure are performed, the separators3are cut between the electrodes adjacent to each other to manufacture the individual unit cells4.

However, the cutter8according to the related art has a structure in which the pressure is applied vertically to cut the separators3. Thus, when any one of the separators3aand3bis not properly cut, there is a problem in that the separators3aand3bare folded in a direction in which the pressure is applied.

After the unit cells4are manufactured, since the plurality of unit cells4are stacked to be manufactured as an electrode assembly, the folding of the separators3occurs, and thus, when a portion of the negative electrode2or the positive electrode1is exposed, short circuit occurs inside the electrode assembly.

That is, referring toFIG.1a, the points at which the separator3and the electrodes1and2are in contact with each other even after passing through a pressing roller5by passing through the laminating device9. However, in the structure according to the related art, the upper separator3aand the lower separator3bare not bonded as illustrated inFIG.1b, and thus, there is a problem in that the separators are folded.

SUMMARY OF THE DISCLOSURE

Accordingly, a main object of the present invention is to provide a method and apparatus for manufacturing a unit cell, which is capable of preventing upper and lower separators from being folded, thereby preventing short circuit from occurring when the separators are cut, and a unit cell capable of being manufactured through the manufacturing apparatus.

An apparatus for manufacturing a unit cell, which cuts a lower separator and an upper separator between electrodes (a positive electrode and a negative electrode) adjacent to each other (in a longitudinal direction of the separator) in a process of manufacturing the unit cell provided in a state (i.e., a stacked state in the order of the ‘positive electrode/upper separator/negative electrode/lower separator’ or the ‘negative electrode/upper separator/positive electrode/lower separator’ from top to bottom), in which the lower separator and the upper separator continuously move in a longitudinal direction, and the electrodes are stacked between the lower separator and the upper separator and on the upper separator, respectively, according to the present invention for achieving the above object comprises: a lower block disposed under the lower separator; and an upper block which is vertically aligned with the lower block above the upper separator and in which a lower end of a cutter is installed to be accessible to the inside and outside, wherein the upper block descends to press the separators to a surface of the lower block, wherein at least one or more of the upper block and the lower block is heated to a predetermined temperature so that pressed points of the separators are thermally fused, and the cutter protrudes from the upper block to perform cutting at points at which the separators are pressed.

The lower block may be heated to a predetermined temperature, and the upper block may not be heated. The upper block may be heated to a predetermined temperature, and the lower block may not be heated. Both the upper block and the lower block may be heated to a predetermined temperature.

The pressing of the separators may be performed by the upper block, and after a predetermined time elapses, the cutter may protrude to cut the point at which the thermal fusion is performed.

A groove may be formed in a top surface of the lower block so that the cutter is accommodated so as not to be in contact the lower block when the cutter protrudes.

The cutter may be maintained in a state of being accommodated so as not to protrude from the upper block by elasticity of a spring, and when the upper block presses the separators to the lower block, the cutter may protrude. That is, the cutter may be configured to be slidable in a known solenoid method using a spring and an electromagnet.

Furthermore, the present invention provides a unit cell that is capable of being manufactured through the apparatus for manufacturing the unit cell having the above configuration.

A unit cell, in which a lower electrode is stacked between a lower separator and an upper separator, and an upper electrode is stacked on the upper separator, provided in the present invention comprises: a sealing part formed by applying heat and a pressure to an end of an edge of the lower separator protruding from the lower electrode and an end of an edge of the upper separator protruding from the lower electrode, wherein the upper separator has one end connected to the sealing part and the other end connected to face an upper side to form an arc.

Heat may be applied to the connection part. The connection part to which the heat is applied may be stiffened than other portions to maintain a shape of the connection part, and thus, flapping of the sealing part may be prevented.

In addition, a method for manufacturing a unit cell provided in the present invention may be provided.

A method for manufacturing a unit cell, in which electrodes are stacked between a lower separator and an upper separator and on the upper separator, respectively, according to the present invention comprises: a process of providing the electrodes and the separators in a state in which the lower separator and the upper separator continuously move in a longitudinal direction, and the electrodes are stacked between the lower separator and the upper separator and on the upper separator, respectively; and a process of allowing the electrodes and the separators to pass between the lower block disposed under the lower separator and the upper block disposed to be vertically aligned with the lower block above the upper separator, wherein the upper block descends to press the separators to a surface of the lower block between the electrodes adjacent to each other, and a cutter protrudes from the lower block to cut the separators, and at least one or more of the upper block and the lower block is heated to a predetermined temperature to perform thermal fusion at points at which the separators are pressed, and cutter cuts the points at which the thermal fusion is performed.

The predetermined temperature to which the upper block or the lower block is heated may be set in a range of 70° C. to 110° C.

A time taken to allow the upper block to press the separators to the lower block may be 0.05 seconds to 0.1 seconds.

In the present invention having the above-described configuration, since the cutter cuts the upper separator and the lower separator in the state in which the upper separator and the lower separator are fixedly bonded between the upper block and the lower block, the possibility of the folding of the separators may be reduced.

In addition, since the lower block is in the heated state, and the upper block is pressed to achieve the thermal fusion of the separators, the cut portions of the upper separator and lower separator are bonded even after the cutting is performed to fundamentally prevent the possibility of the folding of the separators from occurring.

In addition, the upper block as well as the lower block may be heated so that the thermal fusion of the separators are performed more quickly.

In addition, the unit cell provided in the present invention may be maintained in the uniform shape of the manufactured unit cell by forming the connection part connected to the sealing part on the upper separator. The connection part may be stiffened than other portions by applying the heat to prevent the folding from occurring, and the heat and pressure may be applied to connect the thermally fused sealing part to the other portion to provide the function of mitigating the hardness difference. That is, since the hardness of the sealing part is the highest, the hardness of the connection part is medium, and the hardness of the remaining portion is the lowest, the connection part may have the effect of providing the mitigating function in change of the hardness.

DETAILED DESCRIPTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in such a manner that the technical idea of the present invention may easily be carried out by a person with ordinary skill in the art to which the invention pertains. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

Also, terms or words used in this specification and claims should not be restrictively interpreted as ordinary meanings or dictionary-based meanings but should be interpreted as meanings and concepts conforming to the scope of the present invention on the basis of the principle that an inventor can properly define the concept of a term to describe and explain his or her invention in the best manner.

Examples of a method and apparatus for manufacturing a unit cell4, in which electrodes1and2are respectively stacked between a lower separator3band an upper separator3aand on the upper separator3a, and a unit cell capable of being manufactured through the manufacturing apparatus are provided herein. Hereinafter, embodiments according to the present invention will be described in more detail with reference to the accompanying drawings.

First Embodiment

A method for manufacturing a unit cell is provided according to a first embodiment. An apparatus for manufacturing the unit cell provided in this embodiment may replace a pressing roller5and a cutter8for cutting the separator3or only the cutter8in a process illustrated inFIG.1a.

FIG.2is a simplified left view of a portion of the apparatus for manufacturing the unit cell and a bottom surface of an upper block according to an embodiment, andFIG.3is a side view of the portion of the apparatus for manufacturing unit cells to illustrate a state <I> when the upper block ascends above a lower block, a state <II> when the upper block descends, a state <III> in which a lower end of the cutter is protruding downward, a state <IV> when a cutter returns to its original position, and a state <V> when the upper block returns to its original position.

As illustrated in the drawings, the apparatus for manufacturing the unit cell may be an apparatus for manufacturing a unit cell, which cuts a lower separator3band an upper separator3abetween electrodes1and2adjacent to each other in a longitudinal direction of each of the separators3in a manufacturing process, and comprises a lower block10and an upper block20.

That is, as the apparatus for manufacturing the unit cell, which is provided in this embodiment, is provided at a position disposed in the cutter8according to the related art, the lower separator3band the upper separator3acontinuously move in the longitudinal direction and are provided in a state in which a positive electrode1and a negative electrode2are stacked between the lower separator3band the upper separator3aand on the upper separator3a, respectively, i.e., a state in which a ‘positive electrode/upper separator/negative electrode/lower separator’ or a ‘negative electrode/upper separator/positive electrode/lower separator’ are sequentially stacked from top to bottom.

The lower block10is disposed under the lower separator3band is configured to be provided with a built-in heater12so that a surface (particularly, a top surface) thereof is heated to a predetermined temperature or configured to be heated by heat transferred from a separate heater that is provided at the outside.

The lower block10has a structure in which a groove11is formed in a top surface so that an end of the cutter30is accommodated without being in contact with the end when protruding from the upper block20, which will be described later, and the top surface has a plane to support the lower separator3bin a flat state.

Also, the upper block20is vertically aligned with the lower block10above the upper separator3aand has a structure in which the end of the cutter30is installed to be accessible to the inside and outside.

Furthermore, although not shown in the drawings, the upper block20is also configured to be provided with a built-in heater or configured to be heated by heat transferred from a separate heater that is provided at the outside, like the lower block10.

The cutter30is configured to be maintained in a state of being accommodated without protruding from a bottom surface of the upper block20by elastic force of a spring (not shown) and configured so that, when the upper block20descends, the end protrudes to the outside of a bottom surface of the upper block by a physical device, an electric device, etc.

For example, an upper end of the cutter30may be connected to a tensile spring (not shown) so as to be maintained in the state accommodated in the upper block20. That is, the upper end of the cutter30may be connected to a solenoid device to operate so that, when current flows through the solenoid, a lower end of the cutter30protrudes to the outside of the upper block20because electromagnetic force overcomes elastic force of the tensile spring. The cutter30may have a linear structure to correspond to a width of the separator3, and although the end is illustrated as being blunt in the drawings, the end of the cutter30may have a pointed shape in reality. Alternatively, the device for allowing the cutter30to protrude may be implemented not only as the solenoid device using an electromagnet, but also as an electric device using a motor and a gear, a cylinder device using a hydraulic pressure or pneumatic pressure, and the like.

The upper block20may be connected to a lift device (not shown) so as to be elevated vertically. As a result, as illustrated inFIG.3, the upper block may be spaced a predetermined distance upward from the lower block10(<I> state), may descend to be in contact with a top surface of the lower block10(<II> state), and may allow the lower end of the cutter30to protrude downward in the descending state (<III> state).

When the upper block20descends, the upper block20may press the separators3aand3bwith a sufficient pressure so that the separators3aand3bare thermally fused. Here, at least one or more of the upper block20and the lower block10is in a state that is previously heated to a predetermined temperature.

And, when the cutting is completed, the cutter30returns to its original position (<IV> state), and the upper block20also returns to its initial position (<V> state).

As described above, a surface of at least one of the upper block20or the lower block10is heated by the heater. Here, heat may be concentrated to the surface the upper block20, which is in contact with each of the upper separator3aand the lower separator3b. Particularly, when the upper block20is cut in the heated state, a unit cell provided with a sealing part3dand a connection part3c, which are provided in a third embodiment below, may be manufactured.

For reference, the lifting device for elevating the upper block20may be a motor or a hydraulic or pneumatic cylinder. In addition, a separate control and measuring equipment for precisely controlling straightness of the upper block20when ascending and descending may be added. In addition, the lower block10as well as the upper block20may be made of non-ferrous/ferrous materials with high specific heat, such as NAK80 or Becu25, to achieve efficient heat transfer.

In addition, a known heating method may be applied to the heater12comprised in the lower block10and the heater comprised in the upper block20such as a sheath heater or oil medium heater.

Here, a point to which heat is applied to the separator3may be heated in a range of 70° C. to 110° C. The reason in which the temperature is limited to the range of 70° C. to 110° C. is because, when the temperature is less than 70° C., it is difficult to achieve efficient thermal fusion of the separator3, and when the temperature exceeds 110° C., it is difficult to seal the separator3due to the melted separator3. The temperature range may be adjusted according to a pressure generated between the upper block20and the lower block10.

FIG.4is a side view illustrating a state in which the upper block20descends to press the separators3aand3bto a top surface of the lower block10between adjacent electrodes (between adjacent positive electrodes or between adjacent negative electrodes), and the cutter30protrudes from the upper block20to perform cutting at portions at which the separators3aand3bare thermally fused. Here, the cutting may be performed to be thermally fused after or together with the thermal fusion.

When an operation state of the manufacturing apparatus provided in this embodiment is described with reference toFIGS.3and4, the upper block20stands by in a state of ascending above the lower block10to prevent interference from occurring while the separators3aand3band the electrodes1and2are transferred (see the state <I> ofFIG.3).

When only the upper separator3aand the lower separator3bare disposed between the lower block10and the upper block20and between the positive electrode1and the positive electrode1, which are adjacent to each other (or between the negative electrode and the negative electrode), the movement of the separators3aand3bis temporarily stopped.

Next, the upper block20descends. Here, since only the lower block10or at least one or both of the lower block10and the upper block20is in the heated state, an area (a portion shaded inFIG.4), on which the pressing is performed, on the separator3is heated. Since the pressing is performed by the heated upper block20in this manner, the thermal fusion (sealing) is performed at the portions at which the upper separator3aand the lower separator3bare in contact with each other.

Finally, as illustrated inFIG.4, the lower end of the cutter30protrudes to pass through the thermally fused portion to cut the separator3.

Here, it is preferable that the separator3is cut after being sealed. However, since the separator3is in the fixed state between the upper block20and the lower block10, the sealing and cutting may be performed at the same time.

Second Embodiment

In a second embodiment, a method for manufacturing a unit cell, which is capable of manufacturing the unit cell using the above-described manufacturing apparatus is provided.

The manufacturing method provided in this embodiment comprises a process of laminating a separator3and electrodes1and2after stacking the separator3and the electrodes1and2in a predetermined order to provide the separator3and the electrodes1and2and a process of allowing the electrodes1and2and the separator3to pass between a lower block10and an upper block20.

That is, In the process of providing the separator3and the electrodes1and2, a lower separator3band an upper separator3acontinuously move in a longitudinal direction, and also, the electrodes1and2and the separators3are provided in a state in which the electrodes1and2are stacked between the lower separator3band the upper separator3aand on the upper separators3a, respectively.

In addition, in the process of allowing the electrodes1and2and the separator3to pass between the lower block10and the upper block20, the electrodes1and2and the separator3pass between the lower block10disposed under the lower separator3band the upper block20disposed above the upper separator3aso as to be vertically aligned with the lower block10.

In this process, the upper block20descends between the electrodes1and2adjacent to each other to press a surface of the lower block10, and a lower end of a cutter30protrudes from the upper block20to cut the separators3aand3b. Here, at least one or both of the lower block10and the upper block20are heated to a predetermined temperature, and the upper block20is pressed to a pressure at which the separators3aand3bare thermally fused.

The lower block10and/or the upper block20is/are heated in a range of 70° C. to 110° C., and a time taken to allow the upper block20to press the separators to the lower block10may be 0.05 seconds to 0.1 seconds. The upper block20presses the separators3aand3bto fuse the separators3aand3bto a surface of the lower block10, and simultaneously, the cutter30protrudes, or after the thermal fusion is performed, the cutter30protrudes.

For reference, a pressure at which the upper block20presses the lower block10may be set in a range of 5 kg to 50 kg per unit area (1 cm2or 1 m2), and a sealing area may be flexibly set according to intervals between the adjacent electrodes1and2.

Third Embodiment

In a third embodiment, a unit cell capable of being manufactured using the method and apparatus for manufacturing the unit cell, which have been described above, is provided.

FIG.5is a side view illustrating a shape of a side surface of a unit cell according to an embodiment.

Referring toFIG.5, the unit cell provided in this embodiment has a structure, in which a lower electrode is stacked between a lower separator3band an upper separator3a, and an upper electrode1is stacked on the upper separator.

For reference, the lower electrode that is referred to herein refers to an electrode placed between the upper separator3a, which corresponds to a relatively low side, and the lower separator3b, and the upper electrode refers to an electrode placed on the upper separator3a, which corresponds to a relatively high side. However, this structure does not mean in specifying a positive electrode or a negative electrode. That is, the lower electrode2may be one of a negative electrode or a positive electrode, and the upper electrode1may be the other one of the negative electrode or the positive electrode.

In addition, edges of the upper separator3aand the lower separator3bare boned to each other to form a sealing part3d.

That is, heat and a pressure are applied to an end of the edge end of the lower separator3bprotruding from the lower electrode2and an end of the edge of the upper separator3aprotruding from the lower electrode2to thermally fuse the ends so that the sealing part3dis formed on each of both sides. The sealing part3dis formed by being pressed by the lower block10and the upper block20, which are described above, and cut by a cutter30.

In addition, a lower end of the upper separator3ais connected to the sealing part3d, and the other end of the upper separator3ais connected face an upper side to form an arc.

That is, referring toFIG.4, in the manufacturing apparatus provided in the first embodiment, when the upper block20is heated, the upper separator3aand the lower separator3bare thermally fused between a flat portion20aand a flat portion10aof the lower block to form a sealing part3d. Also, an edge20bof the upper block20, which is not in contact with the lower block10applies heat to the upper separator3a. Here, as the upper block20is pressed, a predetermined tension is also applied to a point at which a connection part3cis formed, and thus, the connection part3cis subjected to tension and heat so as to be formed as an arc corresponding to an edge of the upper block20.

Thus, the connection part3cmay be stiffened than other portions (to which heat is not applied), such as the sealing part3dto which the heat and pressure are applied, and thus, a shape of the connection part3cmay be maintained.

Thus, as a unit cell provided in this embodiment is provided with the sealing part3dand the connecting part3con both sides, manufacturing and cutting may be performed in a uniform form.

Also, the connection part3cmay be stiffened than other portions by applying the heat to prevent the folding from occurring, and the heat and pressure may be applied to connect the thermally fused sealing part to the other portion to provide the function of mitigating the hardness difference. That is, the stiffening of the sealing part3dwhere heat and pressure is concentrated is the highest, the stiffening of the connection part3cto which the pressure and heat are relatively weakly applied is intermediate, and the stiffening of the remaining portion is the lowest, and thus, the connection part3chas an effect of providing a mitigation function in change of the stiffening.

In the above-described configuration, since the cutter30cuts the separator3in a state in which the separator3is fixed between the upper block20and the lower block10, the separator3may reduce possibility of folding.

In addition, since the lower block10and/or the upper block20are/is in the heated state, and the upper block20is pressed to achieve the thermal fusion of the separator, even after the cutting is performed, the cut portions of the upper separator3aand the lower separator may be bonded to each other to fundamentally prevent the separator3from being folded.

While aspects of the present invention have been described with reference to 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.

DESCRIPTION OF THE SYMBOLS