KR101802003B1 - Method for manufacturing secondary battery and secondary battery producted by the same method - Google Patents

Abstract

According to an embodiment of the present invention, there is provided a method of manufacturing an electrode assembly, comprising the steps of: (a) housing an electrode assembly in a square can, and injecting a liquid electrolyte; (b) forming the inside of the square can in a vacuum state, and vaporizing a part of the liquid electrolyte; (c) impregnating the electrolytic solution; (d) impregnating and liquefying the electrolytic solution; And (e) liquefying the electrolyte solution and exhausting gas in the can.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for manufacturing a secondary battery,

One embodiment of the present invention relates to a method for manufacturing a secondary battery and a secondary battery therefor.

In recent years, demand for secondary batteries has been rapidly increasing due to explosive demand of portable electric and electronic devices. In particular, lithium secondary batteries are receiving the greatest attention in terms of high capacity.

On the other hand, as environmental problems are serious, solutions for the global warming phenomenon are continuously being discussed. As a solution to this problem, legislation will be implemented to reduce the use of fossil fuels for automobiles, which are the main cause of global warming, and to make environmentally friendly electric vehicles mandatory. In addition, research and development of electric vehicles (HEV, EV) are being continuously carried out in order to solve the pollution problem, and some commercial vehicles are currently being commercialized. In this case, since a large-capacity battery is required, a new approach to the stability of a secondary battery to be used in an electric vehicle is required. In order to satisfy this, a method of increasing the width and height of the battery has been attempted.

However, such an attempt has the advantage of increasing the capacity of the secondary battery and simplifying the shape of the battery. However, as the area of the battery becomes wider, the electrolyte is uniformly impregnated over the entire surface of the electrode assembly, Uniform electrode reaction over the entire surface of the assembly is difficult. That is, as the capacity of the battery is increased and the area of the electrode assembly of the battery is increased, the impregnation of the electrolyte becomes more important.

This is because when the impregnation of the electrolyte solution in the battery is incomplete, the capacity of the battery is lowered and the non-uniformity of the electrode state is intensified, which may cause problems in safety of the battery.

In addition, when the time required for impregnation of the electrolyte is relatively increased, the productivity of the battery is deteriorated. The impregnation failure of the electrolyte accelerates degradation of the electrode even though the other electrode is in good condition, .

An object of the present invention is to provide a method of manufacturing a secondary battery capable of improving the impregnation performance of an electrolyte and a secondary battery manufactured thereby.

According to an aspect of the present invention, there is provided a method of manufacturing an electrode assembly, comprising the steps of: (a) housing an electrode assembly in a rectangular can and injecting a liquid electrolyte; (b) forming the inside of the square can in a vacuum state, and vaporizing a part of the liquid electrolyte; (c) impregnating the electrolytic solution; (d) impregnating and liquefying the electrolytic solution; And (e) liquefying the electrolytic solution and exhausting gas inside the square can.

In another embodiment of the present invention, there is provided a secondary battery manufactured by the above manufacturing method.

A method of manufacturing a secondary battery according to an embodiment of the present invention utilizes a phenomenon in which a vaporization point of an electrolyte is lowered in a vacuum state (low pressure). In this method, an electrolyte is vaporized at a low temperature in a vacuum state, By impregnation, the impregnation speed and the injection strength can be increased and the efficiency of the manufacturing process can be improved.

In addition, the capacity of the secondary battery can be increased by increasing the liquid strength of the electrolyte, and the stability and lifetime of the secondary battery can be increased.

1 is a schematic view of a configuration of a top cap of a secondary battery.
FIG. 2 illustrates the injection of electrolyte into the square can according to an embodiment of the present invention.
FIG. 3 illustrates a process of impregnating an electrolyte according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail.

According to an embodiment of the present invention, there is provided a method of manufacturing an electrode assembly, comprising the steps of: (a) housing an electrode assembly in a square can, and injecting a liquid electrolyte; (b) forming the inside of the square can in a vacuum state, and vaporizing a part of the liquid electrolyte; (c) impregnating the electrolytic solution; (d) impregnating and liquefying the electrolytic solution; And (e) liquefying the electrolytic solution and exhausting the gas inside the square can.

The manufacturing method of the secondary battery uses the phenomenon that the vaporization point of the electrolyte is lowered in a vacuum state (low pressure). When the electrolyte is vaporized at a low temperature in a vacuum state and impregnated into a gas state at a high diffusion rate, The injection strength A can be increased and the efficiency of the manufacturing process can be improved. Further, the capacity of the secondary battery can be increased by increasing the injection strength (A) of the electrolyte solution, and the stability and life of the secondary battery can be increased.

Hereinafter, a method of manufacturing a prismatic secondary battery according to the present invention will be described in detail for each step.

The electrode assembly includes a cathode, a separator, a cathode, and an electrolytic solution. The electrode assembly is filled with a liquid electrolyte. Is not particularly limited and can be produced by a known production method.

The components of the electrode assembly constituting the secondary battery will be described.

The anode is prepared by applying a mixture of a cathode active material, a conductive material and a binder on a cathode current collector, followed by drying and pressing. If necessary, a filler may be further added to the mixture.

The cathode current collector generally has a thickness of 3 to 500 mu m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel A surface treated with carbon, nickel, titanium, silver or the like may be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

When the cathode active material is not a lithium nickel manganese composite oxide (LNMO), for example, a layered compound such as lithium cobalt oxide (LiCoO ₂ ) or lithium nickel oxide (LiNiO ₂ ) or a compound substituted with one or more transition metal ; 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 , LiMnO ₂ and the like; 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 ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _1-x M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2-x M x O 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 50% 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 thermal 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 that assists in bonding of the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 50 wt% 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 separator may be a conventional porous polymer film used as a conventional separator, for example, a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer The prepared porous polymer film can be used singly or in a laminated form. Non-woven fabrics made of conventional porous nonwoven fabrics, for example, glass fibers having a high melting point, polyethylene terephthalate fibers, and the like can be used, but the present invention is not limited thereto.

The negative electrode is prepared by applying, drying and pressing an anode active material on an anode current collector, and may optionally further include a conductive material, a binder, a filler, and the like as described above.

The negative electrode current collector is generally made to have a thickness of 3 to 500 mu m. Such an anode current collector is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples of the anode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, a surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics.

One embodiment of the present invention may be a secondary battery having a structure in which an electrode assembly is impregnated with a lithium salt-containing electrolyte.

The electrolyte solution containing the lithium salt is composed of an electrolyte solution and a lithium salt. The electrolyte solution may be a non-aqueous organic solvent, an organic solid electrolyte, or an inorganic solid electrolyte, but is not limited thereto.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl Methylene carbonate, gamma-butylolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide , Dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone , Propylene carbonate derivatives, 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, A polymer containing an ionic dissociation group and the like may 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 material that is readily soluble 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 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide.

For the purpose of improving the charge / discharge characteristics and the flame retardancy, the electrolytic solution is preferably mixed with an organic solvent such as pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, Benzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, . In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. FEC (Fluoro-Ethylene Carbonate, PRS (Propene sultone), and the like.

One embodiment of the present invention includes a top cap 200 having an electrode assembly formed by including the components of the electrode assembly in a square can 100 and then having an electrolyte injection port 220 formed on the top of the square can 100 ) Can be mounted.

A partial schematic view of the top cap 200 is shown in FIG. 1, an electrode (for example, an anode) tab of an electrode assembly is electrically connected to a top cap 200 mounted on an upper portion of a square can 100 on which an electrode assembly (not shown) The electrode terminal 210 is protruded. On the other hand, the other electrode (e.g., cathode) tab is electrically connected to the square can 100, and both the square can 100 and the top cap 200 are made of a conductive material, And the top cap 200 itself constitutes another electrode terminal 210. Therefore, the clad metal tape 300 is attached to the top cap 200 so that a metal lead (not shown) can be easily attached to the top cap 200 so as to be electrically connected to the PCB (not shown). The insulating member 212 is inserted into the electrode terminal 210 at the contact portion with the top cap 200 for electrical insulation with the top cap 200. [

The top cap 200 is provided with an electrolyte injection port 220 through which the electrolyte can be injected. After the top cap 200 is mounted on the top of the square can 100 and welded, the electrolyte injection hole 220 The electrolyte can be injected into the square can 100.

The electrolytic solution may be injected into the square can 100 through an electrolyte injection pump, but any electrolytic solution can be used as long as it is commonly used as an electrolyte injection method.

After the electrode assembly is housed in the rectangular can 100 and a liquid electrolytic solution is injected (step (a)), the inside of the square can 100 is formed in a vacuum state, and a part of the electrolytic solution in the liquid phase is vaporized (Step (b)).

The inside of the square can 100 is formed in a vacuum state after the liquid electrolyte is injected into the square can 100 containing the electrode assembly. This is because the vaporization point of the electrolyte is lowered in a vacuum state (low pressure) (Low pressure), the electrolytic solution can be vaporized even at a low temperature, and the vaporized electrolytic solution has a faster diffusion rate than the liquid state, and improves the impregnation speed, Can be increased.

Also, the efficiency of the manufacturing process can be improved as the impregnation speed of the electrolyte increases and the injection strength (A) increases.

The liquid injection strength (A) can be expressed by the following formula.

A (%) = volume of impregnated electrolyte / total volume inside square can × 100

The injection strength (A) refers to the volume ratio of the electrolytic solution impregnated into the total volume of the square can 100.

FIG. 2 shows that the electrolyte 30 is injected into the square can 100 according to an embodiment of the present invention. As shown in FIG. 2, the total volume of the inside of the square can 100 is smaller than the total volume The pores 10 and the square can 100 may include a portion 20 in which the electrolyte solution 30 is not filled.

The inside of the square can 100 may be formed in a vacuum state by vacuuming the air inside the square can 100. In the vacuum process, And may include a process of extracting.

The vacuum pump can be used without limitation as long as it is commonly used in a vacuum process.

The vacuum pressure of the vacuum pump may be 2.0 to 7.0 kPa. If the vacuum pressure is more than 7.0 kPa, the pressure in the electrode assembly may be similar to the atmospheric pressure, so that the vaporization point of the electrolyte may not be lowered, and the vaporization point of the electrolyte solution should not be lowered. And it may be insufficient to improve the impregnation speed and the injection strength (A). If the pressure is less than 2.0 kPa, it may be difficult to control the vacuum pressure, and if the vacuum pressure becomes too low, the vaporization point of the electrolytic solution lowers and the vaporization point may fall below room temperature (25 ° C) have.

By forming the inside of the square can 100 in a vacuum state as described above, it is possible to effectively remove minute bubbles remaining in the electrode assembly, and thus the electrolyte juicer strength A of the electrode assembly can be further increased have.

After forming the inside of the square can 100 in a vacuum state, closing the electrolyte inlet 220 before vaporizing the electrolyte. Closing the electrolyte injection port 220 means closing the injection port 220 into which the electrolyte formed in the top cap 200 can be injected.

By closing the electrolyte injection port 220, external air can be prevented from entering the inside of the square can 100, and the formed vacuum pressure can be maintained.

A part of the electrolytic solution in the square can 100 can be vaporized by heating the square can 100 after the electrolyte injection hole 220 is closed.

The step of vaporizing a part of the liquid electrolyte may be performed by a vacuum state formed inside the square can 100.

If the inside of the square can 100 is formed in a vacuum state, the pressure inside the square can 100 can be lowered and the vaporization point of the electrolytic solution can be lowered. The electrolytic solution having the lower vaporization point can be vaporized at a relatively low temperature under atmospheric pressure have.

In addition, the square can 100 may be heated to vaporize a part of the liquid electrolyte, and the temperature inside the heated square can 100 may be 26 to 60 ° C. If the temperature inside the square can 100 is less than 26 ° C, the internal temperature of the square can 100 does not reach the vaporization point of the electrolyte and may be insufficient for vaporization of the electrolyte. If the temperature exceeds 60 ° C, ≪ / RTI >

The temperature inside the heated square can 100 may suitably be 30 ° C to 60 ° C.

The electrolyte begins to vaporize at 30 캜, but since the impregnation speed increases with increasing temperature, the component of the electrolyte may be slowly heated to less than 60 캜, which causes no chemical change, to increase the impregnation rate.

Among the components of the electrolytic solution, ethyl carbonate, dimethyl carbonate and ethyl methyl carbonate can be added as main components.

The temperature at which the main component of the electrolyte is vaporized under atmospheric pressure is 260.7 占 폚 for ethyl carbonate, 108 占 폚 for ethylmethyl carbonate, and 90 占 폚 for dimethyl carbonate.

However, when the inside of the square can 100 is in a vacuum state, that is, when the vacuum pressure is 2.0 to 7.0 kPa as described above, the electrolyte solution may be vaporized at 30 to 60 ° C. During the vaporization from 30 ° C to 60 ° C, vaporization of dimethyl carbonate, ethylmethyl carbonate and ethyl carbonate, which have low vaporization points, may occur in the electrolytic solution components.

The electrolyte begins to vaporize at 30 캜, but since the impregnation speed increases with increasing temperature, the component of the electrolyte may be slowly heated to less than 60 캜, which causes no chemical change, to increase the impregnation rate.

The step (c) of impregnating the electrolytic solution may be performed after forming the inside of the square can 100 in a vacuum state and vaporizing a part of the liquid electrolytic solution (step (b)).

The electrolyte is impregnated by forming the inside of the square can 100 in a vacuum state, closing the electrolyte injection hole 220, and heating the square can 100 to partially vaporize the electrolyte inside the square can 100 Can be impregnated.

When the square can 100 is heated, the electrolytic solution in the square can 100 can be vaporized. At this time, when the phase change over a certain level from the liquid state to the gaseous state progresses, the inner pressure rises to become the equilibrium state in which the vaporization is no longer carried out, and the electrolyte solution can be impregnated in the equilibrium state.

In the equilibrium state, the electrolytic solution can be impregnated into the liquid state and the gas state. However, since the electrolytic solution existing in the gaseous state diffuses faster than the electrolytic solution of the liquid state, the electrode can be rapidly impregnated in the electrode assembly, May vary depending on the inner size of the square can 100, the vacuum pressure inside the square can 100, and the heating temperature.

(Step (d)) in which the vaporized electrolyte in the square can 100 is liquefied after the electrolytic solution is impregnated (step (c)).

The electrolytic solution may be liquefied by heating the inside of the square can 100 to room temperature. After the electrolytic solution is impregnated, the temperature inside the square can 100 is lowered to room temperature, The electrolytic solution can be phase-changed from the gaseous state to the original liquid state.

((D)) after the electrolytic solution is liquefied (step (e)) of evacuating gas inside the square can 100. The gas in the evacuation step may include gases and bubbles remaining in the square can 100 after the electrolytic solution impregnation. In the evacuation step, gas and bubbles remaining in the square can 100 may be evacuated.

The method of manufacturing the secondary battery may further include an electrolyte pouring step after the steps (a) to (e), and the pouring fluid intensity A in the electrode current collector may further be increased by passing through the electrolyte pouring step .

The electrolyte pouring step may be performed after the general electrolyte impregnation step (steps (a) to (e)), but if the pouring liquid strength A is sufficient in the electrolyte impregnation step, The electrolyte injection step may be omitted.

The electrolytic solution may have a liquid strength (A) of 95.0 to 99.9% by volume expressed by the following formula (1).

The liquid injection strength (A) can be expressed by the following formula.

A (%) = volume of impregnated electrolyte / total volume inside square can × 100

(A) indicates the volume ratio of the electrolyte 30 impregnated into the total volume of the square can 100. The total volume of the interior of the square can 100 may include pores 10 in the electrode assembly and a portion 20 of the square can 100 in which the electrolyte 30 is not filled.

After the gas and bubbles remaining in the square can 100 are exhausted, the step of sealing the electrolyte injection hole 220 may be performed.

The electrolyte injection hole 220 formed on the top cap 200 may be sealed by inserting a ball member 230 made of aluminum or the like and the thin metal plate 240 may be welded thereon. In general, a subsequent process of coating with a resin such as epoxy to ensure the sealing state of the electrolyte injection hole 220 may be further performed.

In another embodiment of the present invention, there is provided a secondary battery manufactured by the method for manufacturing a secondary battery.

The present invention provides a battery module including the secondary battery as a unit battery, and a battery pack including the battery module. The battery pack may be used as a power source for devices requiring high temperature stability, long cycle characteristics, and high rate characteristics.

Specific examples of the device include a power tool which is powered by an electric motor and moves; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (Escooter); An electric golf cart; And a power storage system, but the present invention is not limited thereto.

Hereinafter, the present invention will be described more specifically by way of examples. However, the following examples are intended to aid understanding of the present invention, and the scope of the present invention is not limited to these examples in any sense.

[ Example  One]

1-1. Manufacture of anode

95 wt% of LiCoO ₂ as a positive electrode active material, 3 wt% of Super-P (conductive agent) and 2 wt% of PVdF (binder) were added to NMP (N-methyl-2-pyrrolidone) as a solvent to prepare a positive electrode mixture slurry , Followed by coating, drying and pressing on an aluminum foil to prepare a positive electrode.

1-2. Cathode manufacturing

A negative electrode mixture slurry was prepared by adding 95.5% by weight of artificial graphite, 1.5% by weight of Super-P (conductive agent) and 3% by weight of PVdF (binder) as a negative active material to a solvent NMP, Dried and pressed to prepare a negative electrode.

1-3. Preparation of electrolytic solution

As the electrolyte, 1M LiPF ₆ -containing EC / EMC / DEC system solution was used.

1-4. Manufacture of Secondary Battery

Using Celgard TM as a separator, the positive electrode of 1-1, the negative electrode of 1-2, and the separator were laminated in this order and then taken up to manufacture an electrode assembly. The electrode assembly was housed in a square can 100 and then a top cap 200 having an electrolyte injection port 220 was mounted and the square can 100 and the top cap 200 were welded and bonded.

Thereafter, the electrolyte is injected through the electrolyte injection port 220 formed on the top cap 200, the vacuum pressure of the vacuum pump is adjusted to 5.0 kPa to form a vacuum state inside the square can 100, 220 are closed and the square can 100 is gradually heated at a temperature of 30 DEG C to 60 DEG C to phase-change the electrolyte inside the square can 100 to a gaseous state, then impregnate the electrode assembly with the electrolyte, 100) was cooled to change the electrolyte inside the square can 100 into a liquid phase, and the residual gas and bubbles were exhausted, and then the electrolyte injection port 220 was sealed to fabricate a secondary battery

[ Comparative Example  One]

A positive electrode, a negative electrode and an electrolyte solution were prepared in the same manner as in Example 1, an electrolyte solution was injected, and the electrolyte solution was impregnated with no vacuum and heating to prepare a secondary battery.

[ Comparative Example  2]

A positive electrode, a negative electrode and an electrolyte solution were prepared in the same manner as in Example 1, the electrolyte solution was injected, and the electrolyte solution was impregnated by heating at 90 ° C without vacuum to prepare a secondary battery.

[ Experimental Example ]

1. Measurement of Injection Strength (A)

In order to examine the electrolyte impregnation properties of the secondary batteries manufactured in the above Examples and Comparative Examples 1 and 2, the bulk density of the injected electrolyte was measured by measuring the bulk density (A) of the electrolyte in relation to the total volume inside the square can 100.

Example 1 Comparative Example 1 Comparative Example 2 Injection strength (% by volume) 95.0 89.0 93.0

As shown in Table 1, the liquid injection strength (A) means the volume ratio of the electrolyte impregnated into the total volume in the square can 100, and the inside of the square can 100 is formed in a vacuum state Example 1 in which the electrolyte was impregnated by heating showed that the liquid strength (A) was improved in Comparative Example 1 in which the electrolyte was impregnated without vacuum and heating, and Comparative Example 2 in which the electrolyte was impregnated only by heating without vacuum. Therefore, it can be seen that the electrolyte of Example 1 impregnated with the electrolytic solution was formed in the square can 100 in a vacuum state and impregnated with the electrolytic solution in the electrode assembly in a larger amount.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Those skilled in the art will readily appreciate that many suitable modifications and variations are possible in light of the above teachings. Accordingly, all such modifications and variations as fall within the scope of the present invention should be considered.

10: Porosity in the electrode assembly
20: A portion of the square can not be filled with electrolyte
30: electrolyte
100: square can
200: Top cap
210: electrode terminal
212: Insulation member
220: electrolyte injection hole
230: Ball member
240: metal thin film
300: insulating film

Claims (10)

(a) housing an electrode assembly in a rectangular can, and injecting a liquid electrolytic solution containing a lithium salt and a non-aqueous organic solvent;
(b) forming the inside of the square can in a vacuum state and heating it to vaporize a part of the injected electrolyte;
(c) impregnating the partially vaporized electrolyte;
(d) impregnating and liquefying the electrolytic solution; And
(e) liquefying the electrolytic solution and exhausting the gas inside the square can.
The method according to claim 1,
Wherein the vacuum pressure for forming the vacuum state is 2.0 to 7.0 kPa.
The method according to claim 1,
Wherein the step (b) further comprises forming the inside of the square can in a vacuum state, and then closing the electrolyte injection port before vaporizing the electrolyte.
delete The method according to claim 1,
Wherein the step of vaporizing a part of the electrolyte solution in step (b) is performed at a temperature within the can at 26 to 60 ° C.
The method according to claim 1,
Wherein the liquefaction in the step (d) is performed by reducing the temperature inside the can to room temperature.
The method according to claim 1,
Wherein the gas in the step of exhausting the gas in the can in the step (e) comprises residual gas and bubbles in the can.
The method according to claim 1,
Further comprising the step of injecting the electrolyte after the step (e).
The method according to claim 1,
Wherein the electrolytic solution is injected at a rate of 95.0 to 99.9% by volume based on the injection strength (A) represented by the following formula (1).
[Formula 1]
A (%) = volume of impregnated electrolyte / total volume inside square can × 100
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