Laser welding apparatus

Abstract

A laser welding device according to an embodiment of the present invention comprises: a laser generation unit for generating a laser; a gas shielding unit in which flows a shielding gas for shielding, from the outside, a target welding portion of a secondary battery on which the laser is radiated for a welding process; an exhaust unit that is in communication with the gas shielding unit and sucks in foreign substances generated from the target welding portion and discharges same to the outside; and an airflow changing unit that is installed in the exhaust unit and is capable of changing the airflow in the exhaust unit.

Description

Laser welding device

[0001] The present disclosure relates to a laser welding device.

[0002] Laser welding is performed to manufacture cases for lithium-ion secondary batteries, all-solid-state secondary batteries, etc.

[0003] A laser welding device is a mechanism that performs welding by applying a laser beam to a workpiece, such as a case, under a constant pressure and then irradiating the workpiece with the laser beam up to its melting point. During the process of melting the workpiece using such a laser welding device, foreign substances such as welding spatter and welding fumes are generated. These foreign substances can be critical to the quality stability of secondary batteries, including lithium-ion batteries and all-solid-state batteries.

[0004] The information described above disclosed in the background technology of this invention is intended only to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art.

[0005] The embodiments are intended to provide a laser welding device capable of effectively capturing and removing foreign matter while simultaneously improving welding quality.

[0006] However, the technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems can be clearly understood by those skilled in the art from the description of the invention below.

[0007] A laser welding device according to one embodiment for solving the above technical problem comprises: a laser generating unit that generates a laser; a gas shielding unit in which a shielding gas flows to shield a welding target part of a secondary battery, where the laser is irradiated and a welding process is performed, from the outside; an exhaust unit communicating with the gas shielding unit and sucking in foreign matter generated from the welding target part and discharging it to the outside; and an airflow changing unit installed in the exhaust unit and capable of changing the airflow inside the exhaust unit.

[0008] The above airflow changing part may include a plurality of intake holes formed in the exhaust part, and a hole opening / closing part for opening and closing the plurality of intake holes.

[0009] The hole opening / closing unit may include a hole blocking unit that blocks the plurality of intake holes, and a control unit that controls the hole blocking unit.

[0010] The exhaust section may include an exhaust body installed above the gas shielding section and through which the laser penetrates, and an exhaust duct connected to the side wall of the exhaust body and discharging the foreign matter to the outside.

[0011] The above plurality of intake holes may be formed on the side wall of the exhaust section.

[0012] The plurality of intake holes mentioned above may be formed in a position facing the exhaust duct.

[0013] The hole opening / closing unit can block the plurality of intake holes before and after the welding process.

[0014] The above hole opening / closing unit can open the plurality of intake holes during the welding process.

[0015] The above control unit can control the hole blocking unit to open and close the plurality of intake holes simultaneously or sequentially.

[0016] The exhaust section may further include a laser-transmitting substrate installed on the upper part of the exhaust body through which the laser passes.

[0017] According to the embodiments, by installing an airflow changing unit capable of changing the airflow inside the exhaust unit in real time, foreign matter accumulated inside the exhaust unit before and after the welding process can be effectively discharged to the outside.

[0018] In addition, during the welding process, the shielding gas is uniformly distributed over the upper part of the weld target to prevent oxidation of the weld target and maintain welding quality.

[0019] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0020] Figure 1 is a cross-sectional view of an all-solid-state battery.

[0021] Figure 2 is a cross-sectional view of an all-solid-state battery including a precipitation type cathode.

[0022] FIG. 3 is a perspective view of a laser welding device according to one embodiment.

[0023] FIG. 4 is a cross-sectional view of a laser welding device according to one embodiment.

[0024] FIGS. 5 and 6 are drawings illustrating a method of driving a laser welding device according to one embodiment.

[0025] Hereinafter, embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0026] Furthermore, throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0027] In the drawings, thicknesses have been enlarged to clearly represent various layers and regions, and the same reference numerals have been used for similar parts throughout the specification. When a part such as a layer, film, region, or plate is described as being "on" or "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between. Conversely, when a part is described as being "immediately on" another part, it means that there is no other part in between.

[0028] In addition, the term “layer” here includes not only shapes formed on the entire surface when viewed in a plan view, but also shapes formed on some surfaces. Here, “or” is not interpreted in an exclusive sense, and for example, “A or B” is interpreted to include A, B, A+B, etc.

[0029] cathode for all-solid-state secondary batteries

[0030] In one embodiment, a positive electrode for an all-solid-state secondary battery is provided, comprising a current collector layer and a positive electrode active material layer located on the current collector layer, wherein the positive electrode active material layer comprises at least one of a positive electrode active material, a sulfide-based solid electrolyte, a binder, and a conductive material. However, the positive electrode for an all-solid-state secondary battery is not limited thereto, and may include more or fewer components than the components described above.

[0031] In one embodiment, a positive electrode for an all-solid-state secondary battery is manufactured by applying a positive electrode composition comprising at least one of a positive electrode active material, a sulfide-based solid electrolyte, a binder, and a conductive material to a current collector layer, and then drying and rolling.

[0032] positive electrode active material

[0033] The positive electrode active material may be applied without limitation as long as it is commonly used in all-solid-state secondary batteries. For example, the positive electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium, and may include a compound represented by any one of the following chemical formulas.

[0034] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5);

[0035] Li a A 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0036] Li a E 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0037] Li a E 2-b X b O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0038] Li a Ni 1-b-c Co b X c D α (0.90 ≤ a ≤1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 <α ≤ 2);

[0039] Li a Ni 1-b-c Co b X c O 2-α T α(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0040] Li a Ni 1-b-c Co b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0041] Li a Ni 1-b-c Mr b X c D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2);

[0042] Li a Ni 1-b-c Mr b X c O 2-α T α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0043] Li a Ni 1-b-c Mr b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0044] Li a Ni b HAVE BEEN c G d O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1);

[0045] Li a Ni b Co c Mr d G eO2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤0.5, 0.001 ≤ e ≤ 0.1);

[0046] Li a NiG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0047] Li a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0048] Li a Mn 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0049] Li a Mn2G b O4(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0050] Li a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5);

[0051] QO2; QS2; LiQS2;

[0052] V2O5; LiV2O5;

[0053] LiZO2;

[0054] LiNiVO4;

[0055] Li (3-f) J2(PO4)3(0 ≤ f ≤ 2);

[0056] Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2);

[0057] Li a FePO4(0.90 ≤ a ≤ 1.8).

[0058] In the above chemical formulas, A is selected from the group consisting of Ni, Co, Mn, and combinations thereof; X is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is selected from the group consisting of O, F, S, P, and combinations thereof; E is selected from the group consisting of Co, Mn, and combinations thereof; T is selected from the group consisting of F, S, P, and combinations thereof; G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; Q is selected from the group consisting of Ti, Mo, Mn, and combinations thereof; Z is selected from the group consisting of Cr, V, Fe, Sc, Y, and combinations thereof; and J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof.

[0059] The cathode active material may be, for example, lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt oxide (NC), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium nickel manganese oxide (NM), lithium manganese oxide (LMO), or lithium iron phosphate oxide (LFP).

[0060] The positive electrode active material may include a lithium nickel-based oxide represented by the following chemical formula 1, a lithium cobalt-based oxide represented by the following chemical formula 2, a lithium iron phosphate-based compound represented by the following chemical formula 3, or a combination thereof.

[0061] [Chemical Formula 1]

[0062] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2

[0063] In the above Chemical Formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, and M 1 and M2 Each is independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0064] [Chemical Formula 2]

[0065] Li a2 Co x2 M 3 1-x2 O2

[0066] In the above chemical formula 2, 0.9≤a2≤1.8, 0.6≤x2≤1, and M 3 It is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0067] [Chemical Formula 3]

[0068] Li a3 Fe x3 M 4 (1-x3) PO4

[0069] In the above chemical formula 3, 0.9≤a3≤1.8, 0.6≤x3≤1, and M 4 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0070] Average particle size (D of the above positive active material) 50 The particle size can be 1 μm to 25 μm, for example, 3 μm to 25 μm, 5 μm to 25 μm, 5 μm to 20 μm, 8 μm to 20 μm, or 10 μm to 18 μm. A positive electrode active material having such a particle size range can be harmoniously mixed with other components within the positive electrode active material layer and can achieve high capacity and high energy density.

[0071] The above positive active material may be in the form of secondary particles formed by the aggregation of a plurality of primary particles, or in the form of a single particle. In addition, the above positive active material may be spherical or have a shape close to spherical, or may be polyhedral or amorphous.

[0072] Sulfide-based solid electrolytes

[0073] Sulfide-based solid electrolytes are, for example, Li2S-P2S5, Li2S-P2S5--LiX (where X is a halogen element, e.g., I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are integers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are integers, and M is P, Si, Ge, B, Al, Ga or In), or may include a combination thereof.

[0074] Such sulfide-based solid electrolytes can be obtained, for example, by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10 or 50:50 to 80:20 and optionally heat-treating. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be manufactured. Additionally, ionic conductivity may be further improved by including other components such as SiS2, GeS2, B2S3, etc.

[0075] Mechanical milling or the solution method can be applied as mixing methods for sulfur-containing raw materials to manufacture sulfide-based solid electrolytes. Mechanical milling is a method in which starting materials are placed in a reactor and vigorously stirred with a ball mill or similar device to finely pulverize and mix the starting materials. When using the solution method, starting materials are mixed in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, if heat treatment is performed after mixing, the crystals of the solid electrolyte can become more robust and the ionic conductivity can be improved. For example, a sulfide-based solid electrolyte can be manufactured by mixing sulfur-containing raw materials and heat-treating them two or more times; in this case, a robust sulfide-based solid electrolyte with high ionic conductivity can be produced.

[0076] For example, the sulfide-based solid electrolyte particles may include an argyrodite-type sulfide. The argyrodite-type sulfide is, for example, Li a M b P c S d A e It can be expressed by the chemical formula (where a, b, c, d, and e are all between 0 and 12, M is a metal excluding Li or a combination of multiple metals excluding Li, and A is F, Cl, Br, or I), and as a specific example, Li 7-x PS 6-x A x It can be expressed by the chemical formula (where x is 0.2 or greater and 1.8 or less, and A is F, Cl, Br, or I). Specifically, the azirodite-type sulfide is Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0077] Sulfide-based solid electrolyte particles containing such azirodite-type sulfides have an ionic conductivity of 10 at room temperature, which is the ionic conductivity of a typical liquid electrolyte. -4 to 10 -2 It has high ionic conductivity close to the S / cm range and can form a tight bond between the positive active material and the solid electrolyte without causing a decrease in ionic conductivity, and furthermore, can form a tight interface between the electrode layer and the solid electrolyte layer. An all-solid-state battery including this can improve battery performance such as rate characteristics, Coulomb efficiency, and lifespan characteristics.

[0078] An azirodite-type sulfide-based solid electrolyte can be prepared by mixing, for example, lithium sulfide and phosphorus sulfide, and optionally lithium halide. After mixing these, heat treatment may be performed. The heat treatment may include, for example, two or more heat treatment steps.

[0079] Average particle size (D of sulfide-based solid electrolyte particles according to one embodiment) 50 ) may be 5.0 μm or less, for example, 0.1 μm to 5.0 μm, 0.1 μm to 4.0 μm, 0.1 μm to 3.0 μm, 0.5 μm to 2.0 μm, or 0.1 μm to 1.5 μm. Alternatively, depending on the location or purpose of use, the sulfide-based solid electrolyte particles may have an average particle size (D) of 0.1 μm to 1.0 μm. 50 It may be a small particle having ), or an average particle size (D) of 1.5 μm to 5.0 μm. 50 It may also be a large particle having ). Sulfide-based solid electrolyte particles within this particle size range can effectively penetrate between solid particles within the battery, and exhibit excellent contact with the electrode active material and connectivity between solid electrolyte particles. The average particle size of the sulfide-based solid electrolyte particles may be measured using microscopic images; for example, a particle size distribution is obtained by measuring the size of approximately 20 particles from a scanning electron microscope image, where D 50It could be that it was calculated.

[0080] The content of the solid electrolyte in the anode for the all-solid-state battery may be 0.5 wt% to 35 wt%, for example, 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%. This is the content relative to the total weight of the components in the anode, and specifically, it can be said to be the content relative to the total weight of the anode active material layer.

[0081] In one embodiment, the positive active material layer may comprise, with respect to 100 wt% of the positive active material layer, 50 wt% to 99.35 wt% of a positive active material, 0.5 wt% to 35 wt% of a sulfide-based solid electrolyte, 0.1 wt% to 10 wt% of a fluorine-based resin binder, and 0.05 wt% to 5 wt% of vanadium oxide. When such content ranges are satisfied, the positive electrode for an all-solid-state secondary battery can achieve high capacity and high ionic conductivity while maintaining high adhesion, and the viscosity of the positive electrode composition can be maintained at an appropriate level, thereby improving processability.

[0082] bookbinder

[0083] The binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Representative examples include polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc., but are not limited thereto.

[0084] Challenge

[0085] The above positive active material layer may further include a conductive material. The conductive material is used to impart conductivity to the electrode and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or a combination thereof.

[0086] The conductive material may be included in an amount of 0.1% to 5% by weight, or 0.1% to 3% by weight, relative to the total weight of each component of the anode for the all-solid-state battery, or relative to the total weight of the anode active material layer. Within the above content range, the conductive material can improve electrical conductivity without degrading battery performance.

[0087] When the above positive active material layer further includes a conductive material, the positive active material layer may comprise, with respect to 100 weight% of the positive active material layer, 45 weight% to 99.25 weight% of a positive active material, 0.5 weight% to 35 weight% of a sulfide-based solid electrolyte, 0.1 weight% to 10 weight% of a fluorine-based resin binder, 0.05 weight% to 5 weight% of vanadium oxide, and 0.1 weight% to 5 weight% of a conductive material.

[0088] Meanwhile, the cathode for the lithium secondary battery described above may further include an oxide-based inorganic solid electrolyte in addition to the solid electrolyte described above. The oxide-based inorganic solid electrolyte is, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Lithium Phosphate (Li3PO4), Lithium Titanium Phosphate (Li x Ti y (PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate(Li x La y TiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2계 세라믹스, 가넷(Garnet)계 세라믹스 Li 3+x La3M2O 12 (M= Te, Nb, or Zr; x is an integer from 1 to 10), or may include a combination thereof.

[0089] All-solid-state secondary battery

[0090] In one embodiment, an all-solid-state secondary battery is provided, comprising the aforementioned positive electrode, negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode. The all-solid-state secondary battery may also be referred to as an all-solid-state battery or an all-solid-state lithium secondary battery.

[0091] Figure 1 is a cross-sectional view of an all-solid-state battery.

[0092] Referring to FIG. 1, the all-solid-state battery (1000) may have a structure in which an electrode assembly is stacked, comprising a negative electrode (40) including a negative electrode current collector layer (41) and a negative electrode active material layer (43), a solid electrolyte layer (30), and a positive electrode (20) including a positive electrode active material layer (23) and a positive electrode current collector layer (21), and the assembly is housed in a case such as a pouch. The all-solid-state battery (1000) may further include an elastic layer (50) on the outer side of at least one of the positive electrode (20) and the negative electrode (40). FIG. 1 shows a single electrode assembly including a negative electrode (40), a solid electrolyte layer (30), and a positive electrode (20), but an all-solid-state battery may be manufactured by stacking two or more electrode assemblies.

[0093] cathode

[0094] A negative electrode for an all-solid-state battery may, for example, include a current collector layer and a negative electrode active material layer located on the current collector layer. The negative electrode active material layer may include a negative electrode active material and may further include a binder, a conductive material, and / or a solid electrolyte.

[0095] The negative electrode active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0096] Materials capable of reversibly intercalating / deintercalating lithium ions may include carbon-based negative electrode active materials, such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0097] As an alloy of lithium metal, an alloy of lithium with one or more metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn may be used.

[0098] Si-based or Sn-based negative electrode active materials can be used as materials capable of doping and undoping lithium, and Si-based negative electrode active materials include silicon, silicon-carbon composites, and SiO₂. x (0 <x≤2), Si-Q 합금(Q는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Si은 아님), Sn계 음극 활물질로는 Sn, SnO2, Sn-R 합금(R은 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 원소 Q 및 R로는 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, 및 이들의 조합으로 이루어진 군에서 선택되는 것을 사용할 수 있다.

[0099] The silicon-carbon composite may be, for example, a silicon-carbon composite comprising a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof. As an amorphous carbon precursor, coal-based pitch, mesophase pitch, petroleum-based pitch, coal-based oil, petroleum-based heavy oil, or polymer resins such as phenolic resin, furan resin, or polyimide resin may be used. In this case, the silicon content may be 10% to 50% by weight based on the total weight of the silicon-carbon composite. Additionally, the crystalline carbon content may be 10% to 70% by weight based on the total weight of the silicon-carbon composite, and the amorphous carbon content may be 20% to 40% by weight based on the total weight of the silicon-carbon composite. Additionally, the thickness of the amorphous carbon coating layer may be 5nm to 100nm.

[0100] Average particle size of silicon particles (D 50 ) can be 10 nm to 20 µm, for example, 10 nm to 500 nm. Silicon particles may exist in an oxidized form, wherein the atomic content ratio of Si:O within the silicon particles indicating the degree of oxidation may be 99:1 to 33:67. The silicon particles are SiO x It can be a particle, and in this case, SiO x In this case, the range of x can be greater than 0 and less than or equal to 2. Here, the average particle size (D 50 ) is measured by a particle size analyzer using laser diffraction and refers to the diameter of a particle with a cumulative volume of 50 volume% in the particle size distribution.

[0101] A Si-based negative electrode active material or a Sn-based negative electrode active material may be used in combination with a carbon-based negative electrode active material. The mixing ratio of the Si-based negative electrode active material or the Sn-based negative electrode active material and the carbon-based negative electrode active material may be 1:99 to 90:10 by weight.

[0102] The content of the negative electrode active material in the negative electrode active material layer may be 95% to 99% by weight relative to the total weight of the negative electrode active material layer.

[0103] In one embodiment, the negative active material layer further comprises a binder and optionally further comprises a conductive material. The content of the binder in the negative active material layer may be 1% to 5% by weight with respect to the total weight of the negative active material layer. Additionally, when further comprising a conductive material, the negative active material layer may comprise 90% to 98% by weight of the negative active material, 1% to 5% by weight of the binder, and 1% to 5% by weight of the conductive material.

[0104] The above binder serves to effectively bond the negative electrode active material particles to each other and also to effectively bond the negative electrode active material to the current collecting layer. The above binder may include a water-insoluble binder, a water-soluble binder, or a combination thereof.

[0105] The above-mentioned water-insoluble binder may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer comprising ethylene oxide, an ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0106] Examples of the above water-soluble binders include rubber-based binders or polymer resin binders. The rubber-based binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, and combinations thereof. The polymer resin binder may be selected from polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0107] When a water-soluble binder is used as the above-mentioned cathode binder, a thickener capable of imparting viscosity may be used together, and the thickener may include, for example, a cellulose-based compound. The cellulose-based compound may include carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, alkali metal salts thereof, or combinations thereof. Na, K, or Li may be used as the alkali metal. The content of such a thickener may be 0.1 to 3 parts by weight per 100 parts by weight of the cathode active material.

[0108] The above conductive material is used to impart conductivity to an electrode and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes; metal-based materials in the form of metal powder or metal fibers including copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0109] The above cathode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0110] As another example, the negative electrode for the all-solid-state battery may be a precipitation type negative electrode. The precipitation type negative electrode refers to a negative electrode that does not contain a negative electrode active material when assembling the battery, but where lithium metal, etc., is precipitated during charging of the battery and acts as the negative electrode active material.

[0111] Figure 2 is a cross-sectional view of an all-solid-state battery including a precipitation type cathode.

[0112] Referring to FIG. 2, the precipitation type negative electrode (40') may include a current collection layer (41) and a negative electrode coating layer (45) located on the current collection layer (41). In an all-solid-state battery having such a precipitation type negative electrode (40'), initial charging is started in a state where no negative electrode active material is present, and during charging, high-density lithium metal, etc. is precipitated between the current collection layer (41) and the negative electrode coating layer (45) to form a lithium metal layer (44), which can act as a negative electrode active material. Accordingly, in an all-solid-state battery that has undergone one or more charging cycles, the precipitation type negative electrode (40') may include a current collection layer (41), a lithium metal layer (44) located on the current collection layer (41), and a negative electrode coating layer (45) located on the metal layer. The lithium metal layer (44) refers to a layer in which lithium metal, etc. is precipitated during the charging process of the battery and may be referred to as a metal layer or a negative electrode active material layer.

[0113] The cathode coating layer (45) may include a metal, carbon material, or a combination thereof that acts as a catalyst.

[0114] The metal may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or combinations thereof, and may consist of one of these or may consist of several types of alloys. If the metal exists in the form of particles, its average particle size (D 50 ) can be about 4 μm or less, and for example, 10 nm to 4 μm.

[0115] The carbon material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof. Crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon micro beads, or a combination thereof. Amorphous carbon may be, for example, carbon black, activated carbon, acetylene black, Denka black, Ketjen black, or a combination thereof.

[0116] When the negative electrode coating layer (45) includes both metal and carbon material, the mixing ratio of the metal and carbon material may be, for example, a weight ratio of 1:10 to 2:1. In this case, the precipitation of lithium metal can be effectively promoted and the characteristics of the all-solid-state battery can be improved. The negative electrode coating layer (45) may include, for example, a carbon material supported with a catalyst metal, or may include a mixture of metal particles and carbon material particles.

[0117] The cathode coating layer (45) may include, for example, a metal and amorphous carbon, and in this case, can effectively promote the precipitation of lithium metal.

[0118] The cathode coating layer (45) may further include a binder, and the binder may be a conductive binder. Additionally, the cathode coating layer (45) may further include common additives such as fillers, dispersants, ion conductive agents, etc.

[0119] The thickness of the cathode coating layer (45) may be, for example, 100 nm to 20 μm, or 500 nm to 10 μm, or 1 μm to 5 μm.

[0120] The precipitation type cathode (40') may further include a thin film on the surface of the current collector layer (41), for example, between the current collector layer (41) and the cathode coating layer (45). The thin film may include an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and may be composed of one of these or composed of several types of alloys. The thin film can further flatten the precipitation shape of the lithium metal layer (44) and further improve the characteristics of the all-solid-state battery. The thin film may be formed by, for example, vacuum deposition, sputtering, plating, etc. The thickness of the thin film may be, for example, 1 nm to 500 nm.

[0121] solid electrolyte layer

[0122] The solid electrolyte layer (30) may include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, etc. The specific details of the sulfide-based solid electrolyte and the oxide-based solid electrolyte are as described above.

[0123] In one example, the solid electrolyte included in the anode (20) and the solid electrolyte included in the solid electrolyte layer (30) may include the same compound or different compounds. For example, if both the anode (20) and the solid electrolyte layer (30) include an azirodite-type sulfide-based solid electrolyte, the overall performance of the all-solid-state secondary battery may be improved. In addition, for example, if both the anode (20) and the solid electrolyte layer (30) include the aforementioned coated solid electrolyte, the all-solid-state secondary battery may achieve high capacity and high energy density while achieving excellent initial efficiency and lifespan characteristics.

[0124] Meanwhile, the average particle size (D) of the solid electrolyte included in the anode (20) 50 ) is the average particle size (D) of the solid electrolyte included in the solid electrolyte layer (30). 50It may be smaller than ). In this case, overall performance can be improved by increasing the mobility of lithium ions while maximizing the energy density of the all-solid-state battery. For example, the average particle size (D) of the solid electrolyte included in the positive electrode (20) 50 ) may be 0.1 μm to 1.0 μm, or 0.1 μm to 0.8 μm, and the average particle size (D) of the solid electrolyte included in the solid electrolyte layer (30) 50 The particle size ) can be 1.5 μm to 5.0 μm, or 2.0 μm to 4.0 μm, or 2.5 μm to 3.5 μm. When such a particle size range is satisfied, the energy density of the all-solid-state secondary battery is maximized, while lithium ion transport is facilitated to suppress resistance, thereby improving the overall performance of the all-solid-state secondary battery. Here, the average particle size (D) of the solid electrolyte 50 ) may be measured using a particle size analyzer utilizing laser diffraction. Alternatively, approximately 20 random particles may be selected from microscopic images such as those of a scanning electron microscope, their particle sizes measured, and their particle size distribution obtained, where D 50 You can also calculate the value.

[0125] The solid electrolyte layer may further include a binder in addition to the solid electrolyte. In this case, the binder may be styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, acrylate-based polymer, or a combination thereof, but is not limited thereto, and any material used as a binder in the relevant technical field may be used. The acrylate-based polymer may be, for example, butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0126] A solid electrolyte layer can be formed by adding a solid electrolyte to a binder solution, coating the mixture onto a substrate film, and drying it. The solvent of the binder solution may be isobutyryl isobutylate, xylene, toluene, benzene, hexane, or a combination thereof. Since the process for forming the solid electrolyte layer is widely known in the field, a detailed description will be omitted.

[0127] The thickness of the solid electrolyte layer can be, for example, 10 μm to 150 μm.

[0128] The solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0129] The alkali metal salt may be, for example, a lithium salt. The content of the lithium salt in the solid electrolyte layer may be 1 M or more, for example, 1 M to 4 M. In this case, the lithium salt can improve ion conductivity by improving the lithium ion mobility of the solid electrolyte layer.

[0130] Lithium salts include, for example, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), and lithium bis(fluorosulfonyl)imide (LiFSI). It may include LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4, or a mixture thereof.

[0131] In addition, the lithium salt may be imide-based, for example, imide-based lithium salts may include lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2) and lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). The lithium salt can maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with the ionic liquid.

[0132] Ionic liquids are salts or room temperature molten salts that have a melting point below room temperature, are in a liquid state at room temperature, and consist only of ions.

[0133] The ionic liquid comprises a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, and mixtures thereof, and b) BF4 - , PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - It may be a compound containing one or more anions selected from among.

[0134] The ionic liquid may be one or more selected from the group consisting of, for example, N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazoliium bis(trifluoromethylsulfonyl)amide, and 1-ethyl-3-methylimidazoliium bis(trifluoromethylsulfonyl)amide.

[0135] The weight ratio of the solid electrolyte to the ionic liquid in the solid electrolyte layer may be 0.1:99.9 to 90:10, and for example, 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. A solid electrolyte layer satisfying the above range can maintain or improve ionic conductivity by increasing the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate characteristics, etc. of the all-solid-state battery can be improved.

[0136] The all-solid-state battery may be a unit cell having a structure of a positive electrode / solid electrolyte layer / negative electrode, a bicell having a structure of negative electrode / solid electrolyte layer / positive electrode / solid electrolyte layer / negative electrode, or a stacked battery in which the structure of the unit cell is repeated.

[0137] The shape of the all-solid-state battery is not particularly limited and can be, for example, coin-type, button-type, sheet-type, stacked-type, cylindrical-type, flat-type, etc. In addition, all-solid-state batteries can be applied to large batteries used in electric vehicles, etc. For example, all-solid-state batteries can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, they can be used in fields requiring a large amount of power storage, and for example, can be used in electric bicycles or power tools.

[0138] Hereinafter, a laser welding device according to one embodiment will be described with reference to FIGS. 3 and FIGS. 4.

[0139] FIG. 3 is a perspective view of a laser welding device according to one embodiment, and FIG. 4 is a cross-sectional view of a laser welding device according to one embodiment.

[0140] As illustrated in FIGS. 3 and 4, a laser welding device according to one embodiment includes a laser generating unit (100), a gas shielding unit (200), an exhaust unit (300), and an airflow changing unit (400).

[0141] The laser generating unit (100) can generate a laser (1). The laser generating unit (100) may be positioned above and spaced apart from the exhaust unit (300). The laser (1) generated from the laser generating unit (100) can pass through the exhaust unit (300) and the gas shielding unit (200) to reach the welding target part (A) of the secondary battery (B). In this embodiment, the welding target part (A) between the case (B1) and the cover (B2) of the secondary battery (B) is shown, but it is not necessarily limited thereto.

[0142] The gas shielding unit (200) includes a shielding body (210) and a shielding gas supply unit (220).

[0143] A welding target part (A) of a welding target (B), such as a secondary battery, may be located inside the shielding body (210). The shielding gas (2) flowing inside the shielding body (210) can shield the welding target part (A) from the outside while the welding process is in progress by irradiating the welding target part (A) with a laser (1), thereby preventing oxidation of the welding target part (A).

[0144] The shielding gas supply unit (220) can supply the shielding gas (2) through a gas supply hole (210a) formed in the side wall of the shielding gas (2). The shielding gas (2) can be supplied in a horizontal direction (X) along the upper part of the welding target (A). This shielding gas (2) may be an inert gas such as nitrogen.

[0145] The exhaust unit (300) is installed on the gas shielding unit (200) and can suck in foreign matter (10) generated from the welding target part (A) and discharge it to the outside. Here, the foreign matter (10) may be welding spatter, welding fume, etc. generated during the process of melting the welding target part (A).

[0146] The exhaust section (300) may include an exhaust body (310), an exhaust duct (320), and a laser-transmitting substrate (330).

[0147] The exhaust body (310) is connected to the gas shielding part (200) and can be penetrated by the laser (1). In this embodiment, the exhaust body (310) has a structure that is extended in the vertical direction (Z) so that the laser (1) can penetrate it, but it is not necessarily limited to this.

[0148] The exhaust duct (320) is connected to the side wall of the exhaust body (310) and can discharge foreign matter (10) to the outside. A suction device (not shown) that provides the force to discharge foreign matter (10) to the outside may be connected to this exhaust duct (320).

[0149] A laser-transmitting substrate (330) through which the laser (1) passes can be installed on the upper part of the exhaust body (310). This laser-transmitting substrate (330) can be made of a transparent material such as glass so that the laser (1) passes through while simultaneously blocking the interior of the exhaust body (310) from the outside.

[0150] Since this exhaust unit (300) performs only suction using a suction device, only a constant airflow is formed inside the exhaust body (310), so when foreign matter (10), such as welding fume generated during the welding process, accumulates, it is difficult to remove the foreign matter (10) and it is also difficult to ensure that the shielding gas (2) is uniformly distributed on the upper part of the welding target (A). To prevent this, an airflow changing unit (400) may be installed in this embodiment.

[0151] The airflow changing unit (400) is installed in the exhaust unit (300) and can change the airflow inside the exhaust unit (300).

[0152] The airflow changing section (400) may include a plurality of intake holes (410) and a hole opening / closing section (420).

[0153] A plurality of intake holes (410) may be formed on the side wall of the exhaust body (310). Additionally, a plurality of intake holes (410) may be formed at a position facing the exhaust duct (320). These plurality of intake holes (410) may be arranged in a vertical direction (Z).

[0154] The hole opening / closing unit (420) can open / close a plurality of intake holes (410). The hole opening / closing unit (420) may include a hole blocking unit (421) and a control unit (422).

[0155] The hole blocking part (421) is positioned corresponding to a plurality of intake holes (410) and can open or block the plurality of intake holes (410).

[0156] The control unit (422) can control the hole blocking unit (421).

[0157] Before and after the welding process, the control unit (422) can control the hole blocking unit (421) to block a plurality of intake holes (410). And, during the welding process, the control unit (422) can control the hole blocking unit (421) to open a plurality of intake holes (410).

[0158] The control unit (422) can control the hole blocking unit (421) to open and close a plurality of intake holes (410) simultaneously or sequentially.

[0159] Since the airflow inside the exhaust section (300) can be changed in real time using this airflow changing section (400), foreign matter (10) accumulated inside the exhaust section (300) can be easily discharged to the outside before and after the welding process, and during the welding process, the negative pressure inside the gas shielding section (200) can be minimized so that the shielding gas (2) is uniformly distributed over the upper part of the welding target (A), thereby preventing oxidation of the welding target (A).

[0160] Below, with reference to the drawings, a method for operating a laser welding device using an airflow changing unit is described in detail.

[0161] FIGS. 5 and 6 are drawings illustrating a method of driving a laser welding device according to one embodiment, FIG. 5 is a drawing illustrating a method of driving a laser welding device before and after a welding process, and FIG. 6 is a drawing illustrating a method of driving a laser welding device during a welding process.

[0162] As illustrated in FIG. 5, prior to the welding process, a plurality of intake holes (410) are blocked using a hole opening / closing part (420) and suction is performed using an exhaust duct (320), thereby changing the airflow inside the exhaust part (300) to form an airflow (3) that is discharged to the outside through the exhaust duct (320). Accordingly, the accumulation of foreign matter (10) caused by stagnant airflow formed inside the exhaust part (300) can be prevented in advance, and the foreign matter (10) remaining inside the exhaust part (300) can be effectively discharged to the outside.

[0163] Next, as illustrated in FIG. 6, during the welding process in which a laser (1) is irradiated onto a welding target (A) to perform welding, a plurality of intake holes (410) are opened using a hole opening / closing part (420), thereby minimizing the negative pressure inside the gas shielding part (200). Accordingly, the shielding gas (2) flowing inside the gas shielding part (200) is uniformly distributed over the upper part of the welding target (A), thereby preventing oxidation of the welding target (A).

[0164] Next, as illustrated in FIG. 5, after the welding process, the hole opening / closing part (420) is used to block the plurality of intake holes (410) again so that the interior of the shielding body (210) functions as an intake pipe, thereby directly sucking in the welding target part (A) and effectively discharging foreign matter (10) to the outside through the exhaust duct (320). In addition, by blocking the plurality of intake holes (410) and sucking using the exhaust duct (320), the airflow inside the exhaust part (300) is changed to remove stagnant airflow and form an airflow (3) that is discharged to the outside through the exhaust duct (320). Therefore, foreign matter accumulated inside the exhaust part (300) can be easily discharged to the outside.

[0165] In this way, by installing the airflow changing part (400), foreign matter (10) is effectively discharged to the outside, and at the same time, the shielding gas (2) is uniformly distributed over the upper part of the welding target part (A), thereby preventing oxidation of the welding target part (A) and maintaining welding quality.

[0166] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

Claims

1. A laser generating unit that generates a laser; A gas shielding part in which a shielding gas flows to shield the welding target part of a secondary battery, where the above laser is irradiated and the welding process is performed, from the outside; An exhaust unit communicating with the above gas shielding unit and sucking in foreign matter generated from the welding target unit and discharging it to the outside; and An airflow changing unit installed in the exhaust section and capable of changing the airflow inside the exhaust section. A laser welding device including 2. In Paragraph 1, The above airflow changing part A plurality of intake holes formed in the exhaust section, and A hole opening / closing unit for opening and closing the plurality of intake holes mentioned above A laser welding device including 3. In Paragraph 2, The above hole opening / closing part A hole blocking member that blocks the plurality of intake holes, and A control unit that controls the above hole blocking part A laser welding device including 4. In Paragraph 3, The above exhaust part An exhaust body installed on the above gas shielding part and through which the laser penetrates, and An exhaust duct connected to the side wall of the above exhaust body and discharging the above foreign matter to the outside A laser welding device including 5. In Paragraph 4, A laser welding device in which the plurality of intake holes are formed on the side wall of the exhaust section.

6. In Paragraph 5, A laser welding device in which the plurality of intake holes are formed in a position facing the exhaust duct.

7. In Paragraph 4, A laser welding device in which the hole opening / closing unit blocks the plurality of intake holes before and after the welding process.

8. In Paragraph 7, A laser welding device in which the hole opening / closing part opens the plurality of intake holes during the welding process.

9. In Paragraph 4, A laser welding device in which the above-described control unit controls the hole blocking unit to open and close the plurality of intake holes simultaneously or sequentially.

10. In Paragraph 4, A laser welding device comprising: the exhaust section further including a laser-transmitting substrate installed on the upper part of the exhaust body through which the laser passes.

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