Patent Description:
Recently, the demand for environmentally-friendly alternative energy sources has become an indispensable factor for future life as the price of energy sources increases due to the depletion of fossil fuels and the concerns on environmental pollution are amplified. Therefore, a lot of research has been focused on various electric power production technologies such as atomic power, solar power, wind power, tidal power, etc., and electric power storage devices for more efficient use of the energy produced as such have been drawing much attention.

Particularly, as technology development and demand for mobile devices increase, the demand for batteries as an energy source is rapidly increasing, and recently, the use of rechargeable batteries as electric vehicles (EVs), hybrid electric vehicles (HEVs), etc., as power sources has been realized, and its application area is expanding to be used as an auxiliary power source, etc., through gridation, and accordingly, a lot of research on batteries that can meet various demands has been conducted.

Typically, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery which can be applied to products such as mobile phones with a thin thickness, etc., with respect to the shape of the batteries, whereas there is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries, which have advantages such as high energy density, discharge voltage, output stability, etc., with respect to materials of the batteries. Additionally, the secondary battery is also classified according to the structure of the electrode assembly which includes an anode, a cathode, and a separator interposed between the anode and the cathode.

Representative examples may include a jelly-roll type (wound type) electrode assembly having a structure in which long sheet-like anodes and cathodes are wound in a state that separators are interposed therebetween; a stacking type electrode assembly in which a plurality of positive electrodes and negative electrodes cut in units of a predetermined size are sequentially stacked in a state that separators are interposed therebetween, etc. Recently, in order to solve the problems of the jelly-roll type electrode assembly and the stacked electrode assembly, a stacking/folding type electrode assembly, which is an electrode assembly having an advanced structure of a mixed type of the jelly-roll type and the stacking type, in which unit cells where positive electrodes and negative electrodes of a predetermined unit are stacked in a state that separators are interposed therebetween, are sequentially wound in a state being disposed on a separator film, is developed.

Additionally, the secondary battery, according to the shape of the battery case, is classified into a cylindrical battery, a prismatic battery in which an electrode assembly is built in a cylindrical or rectangular metal, and a pouch-type battery in which an electrode assembly is built in a pouch-type case of an aluminum laminated sheet.

Generally, a lithium secondary battery performs a formation process during a manufacturing process, and the formation process is a step of activating the battery by performing charging and discharging after assembling the battery, lithium ions discharged from the cathode at the time of charging move into the anode to be inserted thereto, and in particular, a solid electrolyte interface (SEI) film is formed on the surface of the anode. The formation process generally proceeds by repeating the charging and discharging with a constant current or constant voltage in a certain range.

As such, in the case of the cylindrical battery, the gas generated in the formation conversion process of the battery is concentrated in the winding center portion of the electrode assembly having a relatively small space due to the specificity of the shape of the electrode assembly, thereby forming gas trap, and the gas trap serves as a factor that prevents all portions of the electrode assembly from being completely impregnated in the electrolyte solution, and thus there is a problem in that a lithium precipitation region is generated at the center of the electrode assembly having the gas trap formed thereon.

<FIG> is a vertical cross-sectional view schematically showing the structure of a conventional cylindrical battery cell.

Referring to <FIG>, the cylindrical battery cell <NUM> is manufactured by receiving a wound type electrode assembly <NUM> into a cylindrical case <NUM>, injecting an electrolyte into the cylindrical case <NUM>, and coupling a top cap <NUM> having an electrode terminal (e.g., a positive terminal; not shown) formed thereof into the open top end of the case <NUM>.

The electrode assembly <NUM> has a structure in which an anode <NUM>, a cathode <NUM>, and a separator <NUM> are sequentially stacked and wound in a round shape, where a cylindrical center pin <NUM> is inserted into the wound core (the central portion of the jelly-roll) thereof. The center pin <NUM> is generally made of a metal material to provide a predetermined strength and is formed of a hollow cylindrical structure in which a plate material is bent in a round shape. The center pin <NUM> serves to fix and support the electrode assembly <NUM> and acts as a channel for releasing the gas generated by an internal reaction during charging and discharging and at the time of operation.

However, since the hollow portion of the center pin <NUM> is relatively narrow and fine, the gas generated during the formation process passes through the center portion of the electrode assembly <NUM> through the hollow portion of the center pin <NUM>, is concentrated due to the reasons such as the bottleneck phenomenon, etc., thereby forming gas trap.

Generally, to solve the above problems, the gas trap is naturally removed for a sufficient time by charging the spare battery cell in a SOC range with the highest rate of gas trap formation (i.e., in a particular SOC range where the gas is produced in the highest amount) and undergoing an aging process under predetermined temperature and time.

However, since the aging process requires too much time, the process of manufacturing a battery cell may be delayed, and despite the aging process, it is possible that the gas trap inside may not be completely removed, thus reducing the reliability of the process.

Accordingly, there is a high need for the development of a technology that can fundamentally solve the problem.

<CIT> describes an apparatus and method for enhancing impregnation with electrolyte in a secondary battery. The apparatus for enhancing impregnation of the electrolyte in a secondary battery includes a tray in which at least one battery cell is received, and an oscillation and rotation unit capable of oscillating and rotating the tray simultaneously.

<CIT> relates to electrolyte vacuum pouring and device thereof. A battery jar having an electrode group inserted is fixed on a battery jar fixing tool suspended through a supporting spring by an outside fixing member. After the inside of the jar is decompressed by a vacuum pump from a flexible pipe passing through a sealed cover, the solenoid valve of a flexible pipe is opened, and an electrolyte is poured. At this time, a fine vibrator body such as an electromagnetic vibrator is driven.

<CIT> describes a manufacture of battery and manufacturing device thereof. When the injection of an electrolyte is completed, a cover is opened to release the inside, and vibration is applied to a chamber by a vibration excitor. The vibration excitor is an electromagnetic device applying the vibration having the amplitude of about <NUM>-<NUM> and the frequency of about <NUM>-<NUM> in the vertical direction to a battery can in the chamber.

<CIT> relates to processes for dispersing substances and preparing composite materials. Described are processes for dispersing a plurality of unaggregated particles, such as nanoparticles and microparticles, in a viscous medium. The processes are carried out in a vessel with a standard kettle top. The kettle is partially immersed in a variable frequency heated ultrasonic water bath, i.e. sonicator.

An object of the present invention is to solve the problems of the prior art and technical problems that have been required from the past.

The inventors of the present invention have performed in-depth research and various experiments, and as a result, have confirmed, as to be explained later, that it is possible to more easily remove the gas trap formed at the center of the electrode assembly in the formation process of the battery cell within a short period of time by constituting the gas trap-removing device for manufacturing a battery cell so as to apply vibration to the battery cell receiving unit in a state where the spare battery cell is received in the receiving unit of the battery cell, and accordingly, being capable of reducing time for manufacturing the battery cell and minimizing the possibility that the gas trap remains therein thus improving reliability of the process, and thereby completed the present invention.

The present invention provides a method for manufacturing a battery cell using a gas trap removing device for manufacturing a battery cell, as defined in claim <NUM>, wherein the device is a device for manufacturing a battery cell capable of removing gas trap, comprising a battery cell receiving unit into which the spare battery cell is received; and a vibration applying unit for applying vibration to the battery cell receiving unit, in a state where the spare battery cell is received into the battery cell receiving unit. The method for manufacturing a battery cell includes:.

Accordingly, it is possible to more easily remove the gas trap formed at the center of an electrode assembly in the formation process of a battery cell within a short period of time by applying vibration to a battery cell receiving unit in a state where a spare battery cell is received in the battery cell receiving unit, and accordingly, being capable of reducing time for manufacturing the battery cell and minimizing the possibility that the gas trap remains therein, thereby improving reliability of the process.

Meanwhile, the vibration may be applied by physical stimulation from a vibration applying unit that applies vibration to the battery cell receiving unit.

In a specific embodiment, the physical stimulation may performed by a physical impact being directly applied to the battery cell receiving unit from the vibration applying unit.

That is, the vibration applying unit may be in a structure in which a physical impact is applied by directly contacting the outer surface of the battery cell receiving unit in a state where the vibration applying unit is not in contact with the outer surface of the battery cell receiving unit in which the spare battery cell is received. Accordingly, vibration is applied to the spare battery cell received in the battery cell receiving unit, and thereby the gas trap located at the center of the electrode assembly can be removed.

In another specific embodiment, the physical stimulation may be in a structure in which the physical stimulation is performed by a repetitive flow of the vibration applying unit which is in contact with the battery cell receiving unit.

More specifically, the vibration applying unit may repeatedly flow in a state of being in contact with the outer surface of the battery cell receiving unit, and vibration is applied to the spare battery cell received in the battery cell receiving unit by the flow of the vibration applying unit, and thereby the gas trap located at the center of the electrode assembly can be removed.

In particular, the vibration applying unit can be finely and rapidly flowed in a repetitive manner within a short period of time, thereby maximizing the effect of removing the gas trap.

In still another specific embodiment, the physical stimulation may be performed by an ultrasonic wave.

Generally, ultrasonic wave can apply a regular vibration to the spare battery cell received in the battery cell receiving unit due to inherent high frequency. Accordingly, the gas trap in the spare battery cell can be more easily removed.

In particular, the ultrasonic wave may have a frequency of <NUM> to <NUM> and an amplitude of <NUM> to <NUM>.

If the frequency and the amplitude of the ultrasonic wave are lower than the above range, the effect of removing the desired gas trap cannot be exhibited. If the frequency and the amplitude of the ultrasonic wave are higher than the above range, efficiency in the manufacturing process is reduced, and durability of the battery cell may be deteriorated due to excessive vibration, and is thus not preferable.

In particular, as explained above, the vibration is applied by physical stimulation from the vibration applying unit, and specifically, the physical stimulation may be performed by a physical impact directly applied to the battery cell receiving unit from the vibration applying unit, a repetitive flow of the vibration applying unit in contact with the battery cell receiving unit, or ultrasonic wave.

Additionally, the vibration may be applied once, or at least twice periodically or aperiodically, to improve efficiency.

In particular, it is obvious that the number and the period of the physical stimulation applied from the vibration applying unit can be appropriately selected according to conditions such as quantity and size of the spare battery cells received in the battery cell receiving unit.

Hereinafter, the present invention is further described with reference to the drawings according to the embodiments of the present invention.

Disclosed in <FIG> is a schematic view schematically showing the structure of a gas trap removing device for manufacturing a battery cell.

Referring to <FIG>, the gas trap removing device <NUM> for manufacturing a battery cell includes a battery cell receiving unit <NUM> and a vibration applying unit <NUM>.

The battery cell receiving unit <NUM> has an open top surface and is formed in a shape concavely recessed in the downward direction.

Accordingly, the spare battery cell <NUM> can be more easily stored and removed through the open top surface of the battery cell receiving unit <NUM>, and the sidewall <NUM> of the battery cell receiving unit <NUM> formed according to the recessed shape can prevent the flow and damage of the spare battery cell <NUM> due to vibration applied from the vibration applying unit <NUM> by stably supporting the spare battery cell <NUM>.

The spare battery cell <NUM> is stored in the battery cell receiving unit <NUM> in a state being charged in the range of <NUM> SOC to <NUM> SOC.

The spare battery cell <NUM> is supported in a liquid medium about <NUM>% based on the outer surface area in a state where the spare battery cell <NUM> is received in the battery cell receiving unit <NUM>.

Accordingly, the vibration from the vibration applying unit <NUM> can be more effectively transmitted to the spare battery cell <NUM> through the liquid medium <NUM> while minimizing the loss.

Additionally, the vibration from the vibration applying unit <NUM> can be uniformly transmitted to most parts of the spare battery cell <NUM> supported in the liquid medium <NUM>, and thus, It is possible to effectively prevent problems such as short-circuiting of the electrode assembly, which may occur when vibrations are concentrated on a specific area, such as an area adjacent to the vibration applying unit <NUM>, with the battery cell receiving unit <NUM> interposed therebetween.

The vibration applying unit <NUM> is formed of an ultrasonic wave horn having a circular cylindrical shape and is disposed being in contact with the lower surface <NUM> of the battery cell receiving unit <NUM>.

The vibration applicator <NUM> applies an ultrasonic wave having a frequency of <NUM> to <NUM> and an amplitude of <NUM> to <NUM>. Accordingly, the ultrasonic wave vibrates the liquid medium <NUM>, and this vibration is applied to the spare battery cell <NUM> received in the battery cell receiving unit <NUM>, so that the gas trap at the center of the electrode assembly can be removed.

The physical stimulation performed by the ultrasonic wave of the vibration applying unit <NUM> may be applied once or at least twice periodically or aperiodically. Additionally, it is obvious that the vibration applying unit <NUM> may apply vibration through the ultrasonic wave in a state where the vibration applying unit <NUM> is in close contact with the battery cell receiving unit <NUM> in one or various directions of at least two, according to the number of the spare battery cells <NUM> received in the battery cell receiving unit <NUM>, the size of the battery cell receiving unit <NUM>, etc..

Disclosed in <FIG> and <FIG> are schematic views schematically showing the structure of another gas trap removing device for manufacturing a battery cell.

First, referring to <FIG>, the gas trap removing device <NUM> for manufacturing a battery cell has the same constitution as that of the gas trap removing device <NUM> shown in <FIG> (<NUM> of <FIG>) of the gas trap removing device for manufacturing a battery cell, with regard to the remaining constitution except for the vibration applying unit <NUM>.

Specifically, the vibration applying unit <NUM> is a sheet-shaped structure, and is in contact with the lower surface <NUM> of the battery cell receiving unit <NUM>.

The vibration applying unit <NUM> flows finely and rapidly in the left and right direction repeatedly within a short time. Accordingly, the vibration is applied to the spare battery cell <NUM> received in the battery cell receiving unit <NUM> through the liquid medium <NUM>, so that the gas trap at the center of the electrode assembly can be removed.

The vibration of the vibration applying unit <NUM> may be applied once or at least twice periodically or aperiodically, and it is obvious that the vibration applying unit <NUM> may apply vibration through the ultrasonic wave in a state where the vibration applying unit <NUM> is in close contact with the battery cell receiving unit <NUM> in one or various directions of at least two, according to the number of the spare battery cells <NUM> received in the battery cell receiving unit <NUM>, the size of the battery cell receiving unit <NUM>, etc..

Referring to <FIG>, the gas trap removing device <NUM> for manufacturing a battery cell has the same constitution as that of the gas trap removing device <NUM> shown in <FIG> (<NUM> of <FIG>) of the gas trap removing device for manufacturing a battery cell, with regard to the remaining constitution except for the vibration applying unit <NUM>.

Specifically, the vibration applying unit <NUM> is located in the sidewall <NUM> direction of the battery cell receiving unit <NUM>, and vibration is applied to the spare battery cell <NUM> received in the battery cell receiving unit <NUM> through the liquid medium <NUM> by directly applying a physical impact to the sidewall <NUM> of the battery cell receiving unit <NUM>, and accordingly, the gas trap present at the center of the electrode assembly can be removed.

The physical impact may be applied once or at least twice periodically or aperiodically, and it is obvious that the vibration applying unit <NUM> may apply vibration through the ultrasonic wave in a state where the vibration applying unit <NUM> is in close contact with the battery cell receiving unit <NUM> in one or various directions of at least two, according to the number of the spare battery cells <NUM> received in the battery cell receiving unit <NUM>, the size of the battery cell receiving unit <NUM>, etc..

Those of ordinary skill in the art to which the present invention belongs will be able to make various applications and modifications within the scope of the appended claims.

Claim 1:
A method for manufacturing a battery cell using a gas trap removing device for manufacturing a battery cell,
wherein the device is a device for manufacturing a battery cell capable of removing gas trap, comprising:
a battery cell receiving unit into which the spare battery cell is received; and
a vibration applying unit for applying vibration to the battery cell receiving unit, in a state where the spare battery cell is received into the battery cell receiving unit,
wherein the method comprises:
a) a step of charging the spare battery cell in the range of <NUM> state of charge (SOC) to <NUM> SOC;
b) a step of supporting the spare battery cell in a liquid medium, in a state where the spare battery cell is received into the receiving unit of the gas trap removing device;
c) a step of removing gas trap in the spare battery cell by applying vibration to the battery cell receiving unit; and
d) a step of completing a final battery cell by completing the charging and discharging of the spare battery cell.