KR20180023696A - Method of fabricating secondary battery - Google Patents

Abstract

The present invention provides a method for manufacturing a secondary battery capable of sufficiently discharging gas generated during an activation process. The method for manufacturing a secondary battery according to the present invention comprises: a step of inserting an electrode assembly in a battery case, attaching a case cap to an upper end of the electrode assembly, and injecting an electrolyte into the battery case through a main liquid port formed in the case cap; a step of performing cell activation in a dry room environment without blocking the main liquid port; and a step of sealing the main liquid port with a metal ball.

Description

TECHNICAL FIELD The present invention relates to a method of manufacturing a secondary battery,

The present invention relates to a method for manufacturing a secondary battery, and more particularly, to a method for manufacturing a secondary battery while sufficiently discharging gas generated during an activation process.

Secondary batteries are widely used as power sources for mobile devices such as mobile phones, notebooks, and camcorders. Particularly, the use of a lithium secondary battery is rapidly increasing due to the advantage of high operating voltage and high energy density per unit weight.

Such a lithium secondary battery mainly uses a lithium-based oxide as a positive electrode active material and a carbonaceous material as a negative electrode active material, and is generally classified into a lithium ion battery, a lithium ion polymer battery, and a lithium polymer battery depending on the type of an electrolyte used. The battery may be classified into a cylindrical battery, a square battery, and a pouch type battery.

As technology development and demand for mobile devices increase, the demand for secondary batteries as energy sources is rapidly increasing. In recent years, prismatic batteries and pouch-shaped batteries having a smaller width than their length have attracted particular attention due to miniaturization of mobile devices. As the required output of the secondary battery increases, a plurality of battery cells are connected in series or in parallel.

As shown in FIG. 1, the battery cell of the prismatic type secondary battery includes an electrode assembly (not shown) formed of a positive electrode, a negative electrode, and a separator inside a prismatic battery case 10, The electrolyte solution is injected into the battery case 10 through the main liquid port 21 formed in the case cap 20 and assembled.

Thereafter, the metal ball 30 is pressed by the pressing tool 40 to seal the main liquid port 21, thereby preventing the electrolyte from leaking to the outside of the battery case 10.

In the conventional sealing method of the liquid injection port 21, residual gas remains in the battery case 10 after the electrolyte injection. When the liquid injection hole 21 is sealed by the pressure of the metal ball 30, The inside of the case 10 becomes a positive pressure state.

Therefore, a phenomenon that the battery case 10 is swollen due to the pressure inside the battery case 10 occurs, which causes a problem that the quality of the battery cell deteriorates, such as the thickness of a part of the battery cell becomes thick.

In addition, since the main liquid (21) is covered with the metal balls (30) and the activation process is performed, the gas generated during the activation process can not be sufficiently discharged, resulting in defects such as poor cell thickness, .

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method of manufacturing a secondary battery capable of sufficiently discharging gas generated during an activation process.

Other objects and advantages of the present invention will become apparent from the following description, and it will be understood by those skilled in the art that the present invention is not limited thereto. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

According to an aspect of the present invention, there is provided a method of manufacturing a secondary battery, the method comprising: inserting an electrode assembly into a battery case, mounting a case cap on an upper end of the electrode assembly, Injecting an electrolyte solution into the electrolyte; Performing battery activation in a dry room environment without blocking the main liquid port; And sealing the main liquid port with a metal ball.

The step of performing the activation may be one cycle of charging / discharging at a voltage of 2.5 V to 4.8 V, or 5 to 20 times of charging / discharging at a voltage of 4.0 V to 4.8 V.

And removing the gas generated in the step of performing the activation.

The step of removing the gas may be a step of removing the residual gas inside the battery case with a vacuum equipment after the step of performing the activation.

The secondary battery may be a prismatic secondary battery. The main liquid may be formed of one or more circular or polygonal holes.

The secondary battery manufactured according to the present invention can be manufactured as a battery pack including at least one unit battery, and extends to a device including the battery pack as a power source. Such a device may be a mobile phone, a portable computer, a notebook computer, a netbook, a tablet PC, a smart pad, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or a power storage device.

According to the present invention, the cell is activated in the dry room environment without closing the main liquid after the cell assembly, and the main liquid is sealed with the metal ball in the final step. This method facilitates the discharge of the internal gas to reduce the thickness of the cell and the defective reaction failure of the electrode assembly, facilitates the electrode impregnation, shorten the entire process time, and improve the overall process efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention. And should not be construed as limiting.
1 is a view showing a conventional method of sealing a main liquid port of a battery cell.
2 is a flowchart of a method for manufacturing a secondary battery according to the present invention.
3 is a process schematic diagram according to the flowchart of FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

2 is a flowchart of a method for manufacturing a secondary battery according to the present invention. 3 is a process schematic diagram according to the flowchart of FIG. Since the secondary battery of this embodiment has the same appearance as the conventional secondary battery shown in FIG. 1, the same reference numerals are given to the same constituent parts as those of the conventional secondary battery while referring to FIG. 1 as necessary.

Referring to FIGS. 2 and 3, first, battery assembly is performed as in step S10 of FIG. 2 and FIG. 3 (a).

Here, the battery assembly includes an electrode assembly (not shown) built in the battery case 10, a case cap 20 mounted on the top of the battery case 10, To the step of injecting the electrolytic solution into the interior of the electrolytic cell (10).

The battery case 10 may be a rectangular body having a top opened and made of a metal material. The case cap 20 is coupled to the open upper end of the battery case 10 and includes an electrode terminal. The main liquid orifices 21 may be formed in one or more than one. For example, the main liquid orifices 21 may be formed of one or more circular or polygonal holes. At least one auxiliary through hole serving as a discharge port for discharging the air inside the battery case 10 when the electrolyte solution is poured through the auxiliary main liquid port of the main liquid port 21 or the main liquid port 21 may be further formed.

The electrode assembly that can be used in such a secondary battery is not particularly limited as long as it has a structure in which a positive electrode plate, a separator, and a negative electrode plate are stacked and a plurality of electrode tabs are connected to form a positive electrode and a negative electrode. Preferably, a jelly- -Roll) type structure, a stack type structure, a stack-folding type structure, and a lamination-stack type structure. Specifically, the jelly-roll is coated with an electrode active material on a metal foil used as a current collector, dried and pressed, cut in a band shape having a desired width and length, diverged from a cathode and an anode using a separator, To form an elliptical shape on the horizontal cross section.

In the secondary battery of this embodiment, the electrode assembly may preferably have a jelly-roll type winding structure. The battery case 10 is not particularly limited and may be formed of any one of stainless steel, steel, aluminum, and the like.

The positive electrode plate is prepared, for example, by coating a mixture of a positive electrode active material, a conductive material and a binder on a positive electrode current collector, and then drying the resultant. Optionally, a filler may be further added.

The positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 - x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Formula LiNi _1-x MxO ₂ (Here, M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, x = 0.01 ~ 0.3 Im) Ni site type lithium nickel oxide which is represented by; Formula LiMn _{2 - x} MxO ₂ (where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni , Cu or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

The conductive material is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component which assists in bonding of the active material to the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

The negative electrode plate is also manufactured by applying a negative electrode material onto the negative electrode collector and drying the same, and if necessary, the above-described components may further be included.

Examples of the negative electrode active material include carbon such as non-graphitized carbon and graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1 - x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 < x < Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, And Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

A separator is interposed between the anode and the cathode plates, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 mu m and the thickness is generally 5 to 300 mu m. As such a separator, for example, an olefin-based polymer such as polypropylene having chemical resistance and hydrophobicity; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

The electrolytic solution may be, for example, a non-aqueous electrolytic solution containing a lithium salt, which is composed of a polar organic electrolytic solution and a lithium salt. As the electrolytic solution, a non-aqueous liquid electrolytic solution, an organic solid electrolyte, an inorganic solid electrolyte and the like are used.

Examples of the nonaqueous liquid electrolytic solution include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane , Acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate Nonionic organic solvents such as tetrahydrofuran derivatives, ethers, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, Polymers containing ionic dissociation groups, and the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt is a substance which is easily dissolved in the non-aqueous electrolyte. For example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenylborate, .

For the purpose of improving the charge-discharge characteristics and the flame retardancy, the non-aqueous liquid electrolyte may contain, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like are added It is possible. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability, or a carbon dioxide gas may be further added to improve high-temperature storage characteristics.

Conventionally, as described with reference to FIG. 1, the sealing of the main liquid port 21 is completed. However, in the present invention, the main liquid port 21 is not closed. If the electrolytic solution is adhered to the periphery of the main liquid port (21), it is removed by wiping with a cleaning or nonwoven fabric.

Next, the battery activation process is performed as in step S20 of FIG. 2 and FIG. 3 (b).

In the activating step, the cells in the discharged state, which have been assembled, are placed in the Mars equipment, and electrodes are connected and charged. A solid electrolyte inter-phase (SEI) is formed on the surface of the charged cathode by the reaction between the cathode and the electrolyte. That is, the activating step is a charging performed in the process of manufacturing the secondary battery, and means a process of supplying electric energy to the secondary battery to convert it into electrochemical energy. In this case, the activation of the battery is performed in a dry room environment do.

The dry room is different from the conventional dehumidifying room and refers to a room having an indoor air condition at a dew point of -10 ° C or lower, and has been used in a manufacturing process of a lithium secondary battery such as the present invention and a medical field.

The detailed conditions of the battery activation step depend on the type of the electrode active material and the like.

For example, a lithium-containing manganese oxide such as lithium-containing cobalt oxide (LiCoO ₂ ), a layered crystal structure of LiMnO ₂ , a spinel crystal structure of LiMn ₂ O ₄ , lithium-containing nickel oxide (LiNiO ₂ ) In the case of the secondary battery, the activation step may be one charge / discharge in the voltage range of 2.5 V to 4.8 V. That is, after the battery is charged at a high voltage of 4.5 V or higher, the battery may be activated by performing the discharging process to 2.5 V once.

As another example, in the case of using an active material different from that mentioned above, the voltage range of the activation process may be higher than that, for example, 4.0 V to 4.8 V, and the charge / Can be.

Since the main liquid (21) is not blocked during the activation step, the gas is smoothly discharged through the main liquid (21).

And removing the gas generated in the step of performing activation if necessary. This step is shown in FIG. 3 (c), and may be a step of removing the residual gas inside the battery case 10 with the vacuum equipment 25, particularly after the completion of the step of performing the activation. When the residual gas inside the battery case 10 is removed by the vacuum equipment 25, the inside of the battery case 10 can be deaerated under reduced pressure.

The vacuum equipment 25 is disposed above the main liquid 21. At this time, a main lifting member (not shown) is connected to the vacuum equipment 25 to move the vacuum equipment 25 up and down. Thus, the vacuum equipment 25 is detachably connected to the main liquid supply port 21. A vacuum line is installed at one side of the vacuum equipment 25 so as to communicate with the inner space of the vacuum equipment 25. The vacuum line is connected to a vacuum pump (not shown) to suck air in the vacuum space of the vacuum equipment 25 by the operation of the vacuum pump. Further, when the vacuum equipment 25 is connected to the main liquid port 21, residual gas inside the battery case 10 can be sucked together. The inside of the battery case 10 may be made to be in a negative pressure state. Thereafter, when the main liquid port 21 is sealed, there is an effect that the inside of the sealed battery case 10 is maintained at a negative pressure state, thereby preventing the battery case 10 from being swollen.

It is preferable that the vacuum equipment 25 sucks residual gas in the battery case 10 for about 20 to 100 seconds at a negative pressure of about 90 to 120 Pa. When the negative pressure is less than 90 Pa, the gas can not be efficiently removed by the present invention, and when the negative pressure exceeds 120 Pa, the battery case 10 and the electrode assembly may be affected. In the case where the gas suction time using the vacuum equipment 25 is less than 20 seconds, it is impossible to effectively remove the gas pursued by the present invention. If the gas suction time exceeds 100 seconds, the gas removal effect is further reduced, Which is undesirable.

Next, as shown in step S30 and Fig. 3 (d) of Fig. 2, the main liquid hole 21 is sealed with the metal ball 30. [

In addition to the shape of the sphere as shown, the metal ball 30 may be formed in a structure corresponding to the shape of the main liquid hole 21, and may be, for example, a polygonal columnar shape.

It is preferable that the metal ball 30 is formed to have a larger diameter than the main liquid port 21 to completely seal the main liquid port 21. [

And then aging for a period of two to three weeks. So that the electrolyte is evenly distributed to the electrode assembly through the aging period.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not to be limited to the details thereof and that various changes and modifications will be apparent to those skilled in the art. And various modifications and variations are possible within the scope of the appended claims.

10: Battery case 20: Case cap
21: main liquid 25: vacuum equipment
30: metal ball 40: pressing tool

Claims (5)

Inserting an electrode assembly in a battery case, attaching a case cap to an upper end of the electrode assembly, and injecting an electrolyte into the battery case through a main liquid port formed in the case cap;
Performing battery activation in a dry room environment without blocking the main liquid port; And
And sealing the main liquid port with a metal ball.  The method of claim 1, wherein the performing the activation comprises performing charge and discharge once at a voltage band of 2.5 V to 4.8 V, or performing charge and discharge at a voltage band of 4.0 V to 4.8 V five to 20 times Wherein the secondary battery is a single cell.  2. The method of claim 1, further comprising removing gas generated in the step of performing the activation. [5] The method of claim 3, wherein the removing of the gas is a step of removing residual gas in the battery case with a vacuum equipment after the step of performing the activation. [5] The method of claim 4, wherein the vacuum equipment is disposed on an upper portion of the main liquid, and the inside of the battery case is made to be in a negative pressure state.

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