Lithium secondary battery and method for manufacturing the same

Abstract

The present invention relates to a lithium secondary battery, comprising: a battery shell, the internal space of which is divided into one area and another area by a separator; a negative electrode, formed in the one area of ​​the internal space of the battery shell and containing negative electrode active material and negative electrode collector particles; and a positive electrode, formed in the other area of ​​the internal space of the battery shell and containing positive electrode active material and positive electrode collector particles.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0005688, filed on January 16, 2019, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] The invention relates to a lithium secondary battery and a method for manufacturing the same. Background Art

[0005] Recently, with the rapid popularization of electronic devices using batteries such as mobile phones, laptops and electric vehicles, the demand for secondary batteries with small size, light weight and relatively high capacity is increasing rapidly. In particular, lithium secondary batteries have attracted much attention as driving power sources for portable devices due to their light weight and high energy density. Therefore, research and development to improve the performance of lithium secondary batteries has been continuously devoted.

[0006] The lithium secondary battery is a device that generates electricity through an electrochemical reaction between a positive electrode and a negative electrode, and generally manufactures an electrode by coating an electrode collector layer with an electrode slurry containing an electrode active material, a conductive material, a binder, etc., followed by rolling and drying.

[0007] On the other hand, with the recent increase in demand for high-capacity, high-output and low-cost lithium secondary batteries, it is necessary to increase the amount of electrode active materials loaded in the battery. However, when the electrode is manufactured by the conventional process as described above, it is worried that the battery defects caused by various processes such as coating, calendering, drying, etc. will increase. Based on the limitation of the process, the loading amount of the electrode active material is unbalanced, and the adhesion of the electrode active material layer to the collector layer is defective. In addition, the conventional process has a problem that the output characteristics of the battery are rapidly deteriorated due to the distance between the collector layer and the upper part of the electrode active material layer.

[0008] Korean Patent Publication No. 10-2016-0053849 discloses a positive electrode active material and a secondary battery including the same.

[0009] [Prior art documents]

[0010] [Patent document]

[0011] Korean Publication Patent No. 10-2016-0053849 Summary of the invention

[0012] [Technical issues]

[0013] The present invention relates to providing a lithium secondary battery capable of achieving high capacity and high energy density by using current collector particles as a current collector instead of a conventional plate-shaped current collector.

[0014] The present invention also provides a method of manufacturing a lithium secondary battery, which simplifies the process and improves productivity by omitting a coating process for forming an active material layer, which is essential in a conventional electrode manufacturing process.

[0015] [Technical solution]

[0016] One aspect of the present invention provides a lithium secondary battery, which includes: a battery shell, the interior of which is divided into one area and another area by a separator; a positive electrode, formed in one area inside the battery shell and containing positive electrode active material and positive electrode collector particles; and a negative electrode, formed in another area inside the battery shell and containing negative electrode active material and negative electrode collector particles.

[0017] Another aspect of the present invention provides a method for manufacturing a lithium secondary battery, the method comprising: providing a battery case, the interior of which is divided into one region and another region by a separator; preparing a first mixture containing a positive electrode active material and a positive electrode collector particle, and preparing a second mixture containing a negative electrode active material and a negative electrode collector particle; injecting the first mixture into the one region inside the battery case, and injecting the second mixture into the other region inside the battery case. While applying pressure, the battery case injected with the first mixture and the second mixture is rolled.

[0018] [Beneficial Effects]

[0019] According to the lithium secondary battery of the present invention, since the current collector particles are distributed among the electrode active material, it is possible to solve conventional problems such as output reduction due to an increase in the distance between the current collector layer and the upper portion of the electrode active material layer.

[0020] In addition, according to the lithium secondary battery of the present invention, since a current collector in the form of particles is used instead of a conventional current collector layer, an electrode having high capacity and high energy density at the same thickness can be manufactured compared to a conventional electrode manufactured by a coating method.

[0021] In addition, according to the method for manufacturing a lithium secondary battery of the present invention, the following process is performed: the collector particles are mixed with the electrode active material instead of the conventional plate-shaped collector, and then the resulting mixture is injected into the battery shell. That is, since the process of applying the electrode active material to the electrode collector layer is not performed, the battery manufacturing process can be simplified.

[0022] In addition, according to the method for manufacturing a lithium secondary battery of the present invention, since the positive electrode and the negative electrode can be manufactured integrally in the battery shell, there is no need to manufacture the positive electrode and the negative electrode as separate units and then assemble the units. Therefore, the method for manufacturing a lithium secondary battery of the present invention can simplify the battery manufacturing process and improve productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram for describing a lithium secondary battery of the present invention.

[0024] Figure 2 is a schematic diagram for describing the method of manufacturing a lithium secondary battery of the present invention.

[0025] Figure 3 is a schematic diagram for describing the method of manufacturing a lithium secondary battery of the present invention. DETAILED DESCRIPTION

[0026] The terms and words used in the present specification and claims should not be interpreted as limited to the commonly used meanings or meanings in dictionaries, but should be interpreted with meanings and concepts consistent with the technical scope of the present invention based on the principle that the inventor can appropriately define the concepts of the terms in order to describe the present invention in the best manner.

[0027] The terminology provided herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention.The singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0028] It should be understood that the terms "comprising", "including", and / or "having" when used in this document specify the presence of stated features, numbers, steps, operations, elements, components and / or combinations thereof, but do not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, components and / or combinations thereof.

[0029] In the present invention, the average particle size (D 50 ) can be defined as the particle size corresponding to 50% of the cumulative volume in the particle size distribution curve. The average particle size (D) can be measured using, for example, laser diffraction. 50 ). Laser diffraction methods generally enable the measurement of particle sizes ranging from submicrometers to several millimeters and can produce results with high reproducibility and high resolution.

[0030] Hereinafter, the present invention will be described in detail.

[0031] <Lithium Secondary Battery>

[0032] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. The terms and words used in this specification and claims should not be interpreted as limited to the commonly used meanings or meanings in dictionaries, but should be interpreted with meanings and concepts consistent with the technical scope of the present invention based on the principle that the inventor can appropriately define the concept of the terms in order to describe the present invention in the best manner.

[0033] Therefore, since the embodiments described in this specification and the constructions shown in the drawings are merely exemplary embodiments and do not represent the entire technical scope of the present invention, it should be understood that the present invention covers various equivalent forms, modified forms, and alternative forms at the time of filing this application.

[0034] Figure 1 is a schematic diagram for describing a lithium secondary battery of the present invention.

[0035] See also Figure 1 The lithium secondary battery of the present invention includes: a battery shell 10, the interior of which is divided into one area and another area by a separator 11; a positive electrode 20, which is formed in one area inside the battery shell 10 and contains positive electrode active materials and positive electrode collector particles; and a negative electrode 30, which is formed in another area inside the battery shell 10 and contains negative electrode active materials and negative electrode collector particles.

[0036] In the case of a conventional electrode consisting of a current collector layer and an electrode active material layer, since the current collector layer is disposed at the lower portion of the electrode, the distance between the electrode active material present on the upper portion of the electrode active material and the current collector layer increases, resulting in a decrease in output and an increase in resistance. On the other hand, in the case of the lithium secondary battery of the present invention, since the current collector in the form of particles rather than plates is mixed with the electrode active material, the electrode active material and the current collector particles can be uniformly contacted with each other in the electrode, which is conducive to improving the output characteristics of the battery and reducing resistance.

[0037] In addition, according to the lithium secondary battery of the present invention, since a particle-form current collector is used instead of a plate-form current collector, an electrode having high capacity and high energy density at the same thickness as a conventional electrode can be manufactured.

[0038] The battery case 10 is provided to be used as an outer material of the manufactured battery, and any battery case used in a general lithium secondary battery can be used without limitation. Specifically, the battery case 10 may be in the form of a bag or can, more specifically, in the form of an aluminum bag or can.

[0039] The battery case 10 may include a coating layer including a non-conductive material therein for insulation from the outside of the case.

[0040] The inside of the battery case 10 may be divided into one area and another area by the separator 11. The separator 11 may serve to separate the negative electrode and the positive electrode to prevent a short circuit and provide a channel for lithium ion migration.

[0041] like Figure 1 As shown, the separator 11 divides the inside of the battery case 10 into one region and another region, and the one region and the other region inside the battery case 10 can be respectively set as places to form a positive electrode and a negative electrode.

[0042] As the separator 11, any separator commonly used in the art can be used without limitation. As the separator 11, it is preferred that the separator exhibits low resistance to the migration of electrolyte ions and has excellent electrolyte impregnation ability, and a porous polymer film can be used, for example, a porous polymer film made of polyolefin polymers such as ethylene polymers, propylene polymers, ethylene / butene copolymers, ethylene / hexene copolymers, ethylene / methacrylate copolymers, etc., or a stacked structure of two or more layers thereof. In addition, as the separator 11, an ordinary porous non-woven fabric can be used, for example, a non-woven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, etc. In addition, in order to ensure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymer material and optionally a single-layer or multi-layer structure can be used as the separator 11.

[0043] The battery case 10 may further include a mesh current collector. The mesh current collector may be provided as an additional current collector relative to the positive electrode current collector particles and the negative electrode current collector particles described later, and may be used together with the positive electrode current collector particles and the negative electrode current collector particles to achieve the effect of improving conductivity and adhesion to the positive electrode active material / negative electrode active material.

[0044] In consideration of increasing the loading amount of the positive electrode active material or the negative electrode active material and achieving high energy density, the mesh current collector may have a single layer structure. Specifically, the mesh current collector may have a thickness of 10 nm to 50 nm, preferably 20 nm to 40 nm.

[0045] The battery case 10 may further include a positive electrode tab 12 a and a negative electrode tab 12 b for transferring the generated electrons to the outside.

[0046] The positive electrode 20 is formed in one region inside the battery case 10 and includes a positive electrode active material and positive electrode current collector particles.

[0047] The positive electrode active material may include a compound capable of reversibly intercalating and deintercalating lithium, specifically a lithium composite metal oxide containing lithium and one or more metals such as cobalt, manganese, nickel, and aluminum. More specifically, the lithium composite metal oxide may be a lithium manganese-based oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium cobalt-based oxide (e.g., LiCoO2, etc.), a lithium nickel-based oxide (e.g., LiNiO2, etc.), a lithium nickel manganese-based oxide (e.g., LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2- z Ni z O4 (where 0 < Z < 2), etc.), a lithium nickel cobalt-based oxide (e.g., LiNi 1-Y1 Co Y1 O2 (where 0 < Y1 < 1), etc.), a lithium manganese cobalt-based oxide (e.g., LiCo 1-Y2 Mn Y2 O2 (where 0 < Y2 < 1), LiMn 2-z1 Co z1 O4 (where 0 < Z1 < 2), etc.), a lithium nickel manganese cobalt-based oxide (e.g., Li(Ni p Co q Mn r1 )O2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1), Li(Ni p1 Co q1 Mn r2 )O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2), etc.), or a lithium nickel cobalt transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r3 M S2 )O2 (where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, p2, q2, r3, and s2 are atomic fractions of the respective elements independent of each other, and 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, p2 + q2 + r3 + s2 = 1), etc.), which may be used alone or in combination of two or more thereof. Among those listed above, considering the improvement of the capacity characteristics and stability of the battery, the lithium composite metal oxide may be LiCoO2, LiMnO2, LiNiO2, a lithium nickel manganese cobalt-based oxide (e.g., Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni0.8 Mn 0.1 Co 0.1 )O2, etc.) or lithium nickel cobalt aluminum oxide (e.g. Li(Ni 0.8 Co 0.15 Al 0.05 )O2, etc.). In addition, considering that the type and content ratio of the elements constituting the lithium composite metal oxide are controlled to achieve a significant improvement effect, the lithium composite metal oxide may be Li(Ni 0.6 Mn 0.2 Co 0.2 )O2、Li(Ni 0.5 Mn 0.3 Co 0.2 )O2、Li(Ni 0.7 Mn 0.15 Co 0.15 )O2、Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc., which can be used alone or in combination of two or more thereof.

[0048] The positive electrode 20 may contain 80 to 98 wt %, preferably 82 to 94 wt %, and more preferably 87 to 91 wt % of the positive electrode active material. The content of the positive electrode active material is preferably within the above range in view of improving energy density and output characteristics.

[0049] The average particle size of the positive electrode active material (D 50 ) may be 2 μm to 20 μm, preferably 3 μm to 16 μm. The average particle size of the positive electrode active material is preferably within the above range because the rolling density can be increased to improve the energy density.

[0050] The positive electrode active material may include a first positive electrode active material and a second positive electrode active material that are different from each other. Specifically, the average particle size (D 50 ) may be different from each other, and the average particle size (D 50 ) may be larger than the second positive electrode active material. That is, the bimodal positive electrode active material provided by mixing the first positive electrode active material having a large particle size and the second positive electrode active material having a small particle size can be used to improve the rolling performance and further increase the energy density.

[0051] The average particle size (D 50 ) may be 10 μm to 18 μm, preferably 12 μm to 16 μm, and the average particle size (D 50) may be 2 μm to 8 μm, preferably 3 μm to 6 μm. Its average particle size is preferably within the above range so that the positive electrode active material can be mixed with the collector particles described later, thereby improving the rolling performance and energy density.

[0052] The positive electrode active material may include the first positive electrode active material and the second positive electrode active material in a weight ratio of 60:40 to 90:10, preferably 70:30 to 85:15. In this case, the above-mentioned effects of improving the calendering density and the energy density may be significantly achieved.

[0053] The positive electrode 20 includes positive electrode current collector particles.

[0054] In the present invention, a collector in the form of particles rather than plates is used as a positive electrode collector or a negative electrode collector. In the case of a common electrode manufacturing process, an electrode is usually manufactured by loading and applying an electrode active material (positive electrode active material or negative electrode active material) to a plate-shaped collector layer, which can lead to problems caused by performing a coating process, such as an imbalance in the amount of the electrode active material loaded, adhesion defects caused by an increase in the distance between the electrode active material and the collector, and reduced output. However, in the present invention, since a collector in the form of particles is used, the collector particles are mixed with the electrode active material and distributed among the electrode active material, so that the distance between the electrode active material and the collector particles in the manufactured lithium secondary electrode can be kept uniform, thereby, problems such as reduced output caused by an increase in the distance between the electrode active material and the collector, and reduced bonding force can be solved. In addition, problems such as an imbalance in the amount of the electrode active material loaded and adhesion defects of the electrode active material can be prevented.

[0055] In addition, in the present invention, since a larger amount of electrode active material can be loaded in the same volume compared to a general electrode manufactured using a plate-shaped current collector, a battery with high capacity and high energy density can be manufactured.

[0056] The cathode current collector particles may include at least one selected from the group consisting of aluminum, copper, stainless steel, nickel, and titanium, and preferably include aluminum from the viewpoint of improving the stability of the battery in consideration of the oxidation potential of the cathode active material.

[0057] The average particle size of the positive electrode current collector particles (D 50 ) can be 0.5 μm to 3 μm, preferably 1 μm to 2.5 μm. In order to increase the surface area of ​​the positive electrode collector in contact with the positive electrode active material and improve the calendering density when the positive electrode collector particles are mixed with the positive electrode active material particles, the average particle size of the positive electrode collector particles is preferably within the above range.

[0058] The positive electrode 20 may contain 1 to 15 wt %, preferably 1.5 to 13 wt %, and more preferably 4 to 8 wt % of positive electrode current collector particles. The content of the positive electrode current collector particles is preferably within the above range because the distance between the active material and the current collector can be maintained at an appropriate level, thereby improving the output characteristics of the battery and achieving high energy density of the positive electrode active material.

[0059] The positive electrode current collector particles may have at least one selected from the group consisting of spherical, fibrous and plate-like shapes, preferably at least one selected from the group consisting of spherical and fibrous shapes, and are more preferably spherical in view of increasing the surface area of ​​the positive electrode current collector particles in contact with the positive electrode active material.

[0060] In this specification, the term "spherical" may be understood to include not only a completely spherical shape but also a substantially spherical shape. Here, the term "substantially spherical" may be understood to mean that the particle has a substantially spherical shape or a slightly deformed spherical shape.

[0061] The porosity of the positive electrode 20 may be 20% to 30%, preferably 22% to 28%, and more preferably 24.5% to 25.5%. By including a current collector in particle form, the positive electrode 20 may have the above-mentioned level of porosity. Therefore, the positive electrode active material and the positive electrode current collector particles may be filled to an excellent level, and the pores inside the positive electrode may be reduced, thereby improving the electrical connection between the positive electrode active materials. When the positive electrode includes a current collector in the form of a mesh rather than particles as the positive electrode current collector, warping will inevitably occur between the positive electrode active material and the mesh current collector, increasing the pore content inside the positive electrode, and therefore there is a concern that the electrical connection between the positive electrode active materials is reduced, the resistance of the positive electrode is increased, and the energy density is reduced.

[0062] The porosity of the positive electrode 20 can be adjusted by adjusting the use of positive electrode active materials and positive electrode current collector particles, the average particle size (D 50 ) and / or content, and the degree of rolling in the manufacture of lithium secondary batteries.

[0063] In this specification, the porosity of the positive electrode may be calculated by Formula 1 below.

[0064] [Formula 1]

[0065] Porosity of positive electrode (%) = {1-(true density of positive electrode / electrode density of positive electrode)}×100

[0066] In Formula 1, the true density of the positive electrode is the density of the positive electrode active material layer measured when the positive electrode provided in a certain size is pressed using a pressing device until the thickness of the positive electrode does not change, and the electrode density of the positive electrode is the density of the positive electrode active material layer measured after the positive electrode is provided in a certain size.

[0067] The negative electrode 30 is formed in another region inside the battery case 10 and includes a negative electrode active material and negative electrode current collector particles.

[0068] The negative electrode 30 is as Figure 1 The cathode 20 and the anode 30 may be formed in a region different from the region where the cathode is formed, that is, in another region inside the battery case 10. In other words, the cathode 20 and the anode 30 are formed in different regions inside the battery case 10 while being separated by the separator 11.

[0069] As the negative electrode active material, any negative electrode active material commonly used in the art can be used without limitation, for example, a compound capable of reversibly inserting and deinserting lithium can be used. Specific examples of the negative electrode active material include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, etc.; metal compounds capable of forming alloys with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, Al alloys, etc.; metal oxides capable of doping and dedoping lithium, such as SiO β (0<β<2), SnO2, vanadium oxide or lithium vanadium oxide; or a composite comprising the metal compound and a carbonaceous material, such as a Si-C composite or a Sn-C composite, which can be used alone or in combination of two or more thereof. In addition, as the negative electrode active material, a lithium metal film can be used. In addition, as the carbon material, both low-crystallinity carbon and high-crystallinity carbon can be used. Representative examples of the low-crystallinity carbon include soft carbon and hard carbon, and representative examples of the high-crystallinity carbon include amorphous, plate-like, flaky, spherical or fibrous natural graphite or artificial graphite, floating graphite, pyrolytic carbon, mesophase pitch-type carbon fibers, mesophase carbon microspheres, mesophase pitch and high-temperature calcined carbon, such as coke derived from petroleum or coal tar pitch, etc.

[0070] The negative electrode 30 may contain 80 to 98 wt %, preferably 82 to 94 wt %, and more preferably 87 to 91 wt % of the negative electrode active material. The content of the negative electrode active material is preferably within the above range because energy density and output characteristics can be improved.

[0071] The average particle size of the negative electrode active material (D 50 ) can be 10 μm to 25 μm, preferably 15 μm to 20 μm. Considering that the calendering density can be increased to improve the energy density, and considering increasing the contact with the negative electrode collector particles described later, or reducing the distance between the negative electrode active material and the negative electrode collector particles, the average particle size of the negative electrode active material is preferably within the above range.

[0072] Like the above-mentioned positive electrode current collector particles, the negative electrode current collector particles can play a significant effect of simplifying the battery manufacturing process and improving the output and capacity characteristics of the battery.

[0073] The negative electrode current collector particles may include at least one selected from the group consisting of aluminum, copper, stainless steel, nickel, and titanium, and preferably, copper from the viewpoint of improving battery stability in consideration of oxidation potential of the negative electrode active material.

[0074] The average particle size of the negative electrode current collector particles (D 50 ) can be 0.5 μm to 3 μm, preferably 1 μm to 2.5 μm. Considering increasing the surface area of ​​the negative electrode collector in contact with the negative electrode active material and improving the calendering density when the negative electrode collector particles are mixed with the negative electrode active material particles, the average particle size of the negative electrode collector particles is preferably within the above range.

[0075] The negative electrode 30 may contain 1 wt % to 15 wt %, preferably 1.5 wt % to 13 wt %, and more preferably 4 wt % to 8 wt % of negative electrode current collector particles. The content of the negative electrode current collector particles is preferably within the above range because the distance between the active material and the current collector can be maintained at an appropriate level, thereby improving the output characteristics of the battery and achieving a high energy density of the negative electrode active material.

[0076] The negative electrode current collector particles may have at least one selected from the group consisting of spherical, fibrous and plate-like shapes, preferably at least one selected from the group consisting of spherical and fibrous shapes, and are more preferably spherical in view of increasing the surface area of ​​the negative electrode current collector particles in contact with the negative electrode active material.

[0077] The positive electrode 20 and the negative electrode 30 may each independently further include at least one additive selected from the group consisting of a binder and a conductive material, and preferably include a conductive material in view of improving conductivity.

[0078] The conductive material is used to improve the conductivity of the electrode, and any conductive material can be used without limitation, as long as it does not cause chemical changes in the manufactured battery and has electronic conductivity. Specific examples of the conductive material include graphite, such as natural graphite, artificial graphite, etc.; carbon materials, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, etc.; metal powders or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive whiskers composed of zinc oxide, potassium titanate, etc.; conductive metal oxides, such as titanium oxide, etc.; and conductive polymers, such as polyphenylene derivatives, etc., which can be used alone or in combination of two or more thereof. The positive electrode 20 or the negative electrode 30 can generally contain 1% to 10% by weight, preferably 3% to 8% by weight of the conductive material.

[0079] The binder can be used to improve the cohesion between the active material particles and the adhesion between the active material and the collector particles. Specific examples of the binder include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber, various copolymers thereof, etc., which can be used alone or in combination of two or more thereof. The positive electrode 20 or the negative electrode 30 may include 1% to 10% by weight, preferably 3% to 8% by weight of the binder.

[0080] The porosity of the negative electrode 30 may be 25% to 35%, preferably 27% to 33%, and more preferably 29.5% to 30.5%. By including a current collector in particle form, the negative electrode 30 may have the above-mentioned level of porosity. Therefore, the negative electrode active material and the negative electrode current collector particles may be filled to an excellent level, and the pores inside the negative electrode may be reduced, thereby improving the electrical connection between the negative electrode active materials. When the negative electrode includes a current collector in mesh rather than particle form as the negative electrode current collector, warping will inevitably occur between the negative electrode active material and the mesh current collector, increasing the content of pores inside the negative electrode, thereby causing concerns about reduced electrical connection between the negative electrode active materials, increased resistance of the negative electrode, and reduced energy density.

[0081] The porosity of the negative electrode 30 can be adjusted by adjusting the use of negative electrode active materials and negative electrode current collector particles, the average particle size (D 50 ) and / or content, and the degree of rolling in the manufacture of lithium secondary batteries.

[0082] In the present specification, the porosity of the negative electrode may be calculated by the following Formula 2.

[0083] [Formula 2]

[0084] Porosity of negative electrode (%) = {1-(true density of negative electrode / electrode density of negative electrode)}×100

[0085] In Formula 2, the true density of the negative electrode is the density of the negative electrode active material layer measured when the negative electrode provided in a certain size is pressed using a pressing device until the thickness of the negative electrode does not change, and the electrode density of the negative electrode is the density of the negative electrode active material layer measured after the negative electrode is provided in a certain size.

[0086] The lithium secondary battery of the present invention may further include an electrolyte.

[0087] Examples of the electrolyte used in the present invention include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, inorganic solid electrolytes, molten inorganic electrolytes, etc., which can be used to manufacture lithium secondary batteries, but the present invention is not limited thereto.

[0088] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0089] As the organic solvent, any organic solvent can be used without particular limitation, as long as it can be used as a medium through which ions participating in the electrochemical reaction of the battery can migrate. Specifically, the organic solvent can be: ester solvents, such as methyl acetate, ethyl acetate, γ-butyrolactone, ε-caprolactone, etc.; ether solvents, such as dibutyl ether, tetrahydrofuran, etc.; ketone solvents, such as cyclohexanone, etc.; aromatic hydrocarbon solvents, such as benzene, fluorobenzene, etc.; carbonate solvents, such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), etc.; alcohol solvents, such as ethanol, isopropanol, etc.; nitrile, such as R-CN (R is a C2-C20 hydrocarbon group having a linear, branched or cyclic structure, and may contain an aromatic ring or an ether bond of a double bond), etc.; amides, such as dimethylformamide, etc.; dioxolanes, such as 1,3-dioxolanes, etc.; or cyclopentane sulfone. Among those listed above, carbonate solvents are preferred, more preferably a mixture of cyclic carbonate compounds (e.g., EC, PC, etc.) with high ionic conductivity and high dielectric constant and linear carbonate compounds (e.g., EMC, DMC, DEC, etc.) with low viscosity, which can increase the charge / discharge performance of the battery. In this case, when using a mixture obtained by mixing a cyclic carbonate compound and a linear carbonate compound in a volume ratio of about 1:1 to about 1:9, excellent electrolyte performance can be exhibited.

[0090] As the lithium salt, any compound can be used without particular limitation, as long as it can provide lithium ions for lithium secondary batteries. Specifically, the lithium salt can be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, LiB(C2O4)2, etc. The lithium salt is preferably used in a concentration of 0.1 to 2.0M. When the concentration of the lithium salt is within the above range, the electrolyte has an appropriate level of conductivity and viscosity, thereby being able to exhibit excellent electrolyte properties, and lithium ions can be effectively migrated.

[0091] In addition to the above-mentioned electrolyte components, in order to improve the life characteristics of the battery, inhibit the reduction of the battery capacity, improve the discharge capacity of the battery, etc., the electrolyte may further contain at least one additive selected from the following: halogenated alkylene carbonate compounds (such as difluoroethylene carbonate, etc.), pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-ethylene glycol dimethyl ether, hexamethylphosphoric triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted Oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. The additive may be included in an amount of 0.1 to 5 wt % relative to the total weight of the electrolyte.

[0092] In addition, the present invention provides a battery module including a lithium secondary battery as a unit cell, and a battery pack including the battery module.

[0093] The battery module or battery pack can be used as a power source for one or more medium-to-large-sized devices selected from the following: power tools; electric vehicles (EVs), hybrid electric vehicles (and plug-in hybrid electric vehicles (PHEVs); and power storage systems.

[0094] <Method for Manufacturing Lithium Secondary Battery>

[0095] In addition, the present invention provides a method for manufacturing a lithium secondary battery. The method for manufacturing a lithium secondary battery may be the method for manufacturing the above-mentioned lithium secondary battery.

[0096] Specifically, the method for manufacturing a lithium secondary battery of the present invention includes: providing a battery shell, the interior of the battery shell being divided into one area and another area by a separator; preparing a first mixture containing positive electrode active materials and positive electrode collector particles, and preparing a second mixture containing negative electrode active materials and negative electrode collector particles; injecting the first mixture into the one area inside the battery shell, and injecting the second mixture into the other area inside the battery shell; and rolling the battery shell injected with the first mixture and the second mixture while applying pressure.

[0097] According to the method for manufacturing a lithium secondary battery of the present invention, the following process is performed: the collector particles (positive electrode collector particles or negative electrode collector particles) are mixed with the electrode active material (positive electrode active material or negative electrode active material) instead of the conventional plate-shaped collector layer, and then the resulting mixture is injected into the battery shell. That is, since the conventional process of applying the electrode active material to the electrode collector layer is not performed, the battery manufacturing process can be simplified.

[0098] In addition, according to the method for manufacturing a lithium secondary battery of the present invention, since the positive electrode and the negative electrode can be integrally manufactured in the battery shell, there is no need to manufacture the positive electrode and the negative electrode as separate units and then assemble the units. Therefore, the method for manufacturing a lithium secondary battery of the present invention can simplify the battery manufacturing process and improve productivity.

[0099] In addition, according to the method of manufacturing a lithium secondary battery of the present invention, a battery in which collector particles are distributed among electrode active materials can be manufactured, thereby solving conventional problems such as output reduction due to an increase in the distance between the collector layer and the upper portion of the electrode active material layer.

[0100] In addition, according to the method of manufacturing a lithium secondary battery of the present invention, since a particle-form current collector is used instead of a conventional current collector layer, an electrode having high capacity and high energy density at the same thickness can be manufactured compared to a conventional electrode manufactured by a coating method.

[0101] Figure 2 and Figure 3 is a schematic diagram for describing the method of manufacturing a lithium secondary battery of the present invention.

[0102] See also Figure 2 , the method of manufacturing a lithium secondary battery according to the present invention includes providing a battery case 10 , the interior of which is divided into one area and another area by a separator 11 .

[0103] The details of the battery case 10 and the separator 11 have been described above.

[0104] The method of manufacturing a lithium secondary battery of the present invention includes preparing a first mixture 20a including a positive electrode active material and positive electrode current collector particles and preparing a second mixture 30a including a negative electrode active material and negative electrode current collector particles.

[0105] like Figure 2 As shown, the first mixture 20a may be injected into one region inside the battery case 10 and may be subjected to a process such as a calendaring process to form a positive electrode.

[0106] The first mixture 20a includes positive electrode active materials and positive electrode current collector particles.

[0107] The first mixture 20a may contain 80 to 98 wt %, preferably 82 to 94 wt %, more preferably 87 to 91 wt % of the positive electrode active material. In view of improving energy density and output characteristics, the content of the positive electrode active material is preferably within the above range.

[0108] The first mixture 20a may contain 1 wt % to 15 wt %, preferably 1.5 wt % to 13 wt %, more preferably 4 wt % to 8 wt % of positive electrode current collector particles. The content of the positive electrode current collector particles is preferably within the above range because the distance between the active material and the current collector can be maintained at an appropriate level, thereby improving the output characteristics of the battery and achieving a high energy density of the positive electrode active material.

[0109] Other details about the positive electrode active material and the positive electrode current collector particles are the same as those described above.

[0110] like Figure 2 As shown, the second mixture 30a may be injected into a region different from the region into which the first mixture 20a is injected, that is, another region within the battery case 10, and may be subjected to a process such as a rolling process to form a negative electrode. That is, the first mixture 20a and the second mixture 30a are injected into different regions inside the battery case 10 while being separated by the separator 11.

[0111] The second mixture 30a includes negative electrode active materials and negative electrode current collector particles.

[0112] The second mixture 30a may contain 80 to 98 wt %, preferably 82 to 94 wt %, more preferably 87 to 91 wt % of the negative electrode active material. In view of improving energy density and output characteristics, the content of the negative electrode active material is preferably within the above range.

[0113] The second mixture 30a may contain 1 wt % to 15 wt %, preferably 1.5 wt % to 13 wt %, and more preferably 4 wt % to 8 wt % of negative electrode current collector particles. The content of the negative electrode current collector particles is preferably within the above range because the distance between the active material and the current collector can be maintained at an appropriate level, thereby improving the output characteristics of the battery and achieving a high energy density of the negative electrode active material.

[0114] Other details about the negative electrode active material and the negative electrode current collector particles are the same as those described above.

[0115] The first mixture 20a and the second mixture 30a may each independently further include at least one additive selected from the group consisting of a binder and a conductive material, and preferably include a conductive material in view of improving conductivity.

[0116] The conductive material may be contained in an amount of 1 to 10 wt %, preferably 3 to 8 wt %, relative to the total weight of the first mixture 20a or the second mixture 30a. Other details about the conductive material are the same as those described above.

[0117] The first mixture 20a or the second mixture 30a may contain 1 to 10 wt%, preferably 3 to 8 wt%, of the binder relative to the total weight of the first mixture 20a or the second mixture 30a. Other details about the binder are the same as those described above.

[0118] like Figure 2 As shown, the method of manufacturing a lithium secondary battery of the present invention includes injecting a first mixture 20 a into one region inside a battery case 10 , and injecting a second mixture 30 a into another region inside the battery case 10 .

[0119] The injection of the first mixture 20a and the injection of the second mixture 30a may be performed simultaneously or separately.

[0120] During the injection of the first mixture 20a and the second mixture 30a, a process of vibrating the battery case 10 may be further performed. As a result, the first mixture 20a and the second mixture 30a may be smoothly injected into the interior of the battery case 10, and the pores inside the mixture may be reduced by the vibration applied during the injection, thereby achieving high energy density and high capacity.

[0121] In consideration of smooth injection into the battery case and achieving high energy density, the vibration process may be performed by vibrating the battery case at a frequency of 15 to 45 Hz, preferably 20 to 35 Hz.

[0122] The first mixture 20a and the second mixture 30a may be each independently injected into the battery case 10 in the form of slurry or powder. Preferably, the first mixture 20a and the second mixture 30a are injected into the battery case 10 in the form of powder, which is preferred because the time of the drying process described later can be reduced compared to when injected in the form of slurry, and the calendering process and the drying process can be performed simultaneously to facilitate the simplification of the process. In particular, when the first mixture 20a and the second mixture 30a are injected into the battery case 10 in the form of powder, an adhesive for adhering the electrode active material may not be additionally required, so the increase in the resistance of the electrode caused by the use of the adhesive can be prevented.

[0123] In the case where the first mixture 20a and the second mixture 30a are in powder form, the first mixture 20a and the second mixture 30a may not further contain a solvent. Specifically, in the case where the first mixture 20a and the second mixture 30a are in powder form, the first mixture 20a may be composed of a positive electrode active material, positive electrode current collector particles, and optionally at least one additive selected from the group consisting of a binder and a conductive material, and the second mixture 30a may be composed of a negative electrode active material, a negative electrode current collector particles, and optionally at least one additive selected from the group consisting of a binder and a conductive material.

[0124] In the case where the first mixture 20a and the second mixture 30a are in the form of slurry, in addition to the electrode active material (positive electrode active material or negative electrode active material), electrode current collector particles (positive electrode current collector particles or negative electrode current collector particles) and optionally at least one additive selected from the group consisting of a binder and a conductive material, the first mixture 20a and the second mixture 30a may further include a solvent.

[0125] The solvent may include at least one selected from the group consisting of water and N-methyl-2-pyrrolidone (NMP). The solvent content in the first mixture 20a or the second mixture 30a may be such that the concentration of the solid including the electrode active material (positive electrode active material or negative electrode active material), the electrode current collector particles (positive electrode current collector particles or negative electrode current collector particles), and optionally at least one additive selected from the group consisting of a binder and a conductive material becomes 50 wt % to 95 wt %, preferably 70 wt % to 90 wt %.

[0126] The method of manufacturing a lithium secondary battery of the present invention includes rolling the battery case 10 injected with the first mixture 20 a and the second mixture 30 a while applying pressure.

[0127] like Figure 3 As shown, after the first mixture 20a and the second mixture 30a are injected into the battery case 10, the battery case 10 may be subjected to a calendering process while applying pressure with a pressure applying device or the like. Through the calendering process, the pores in the battery case 10 may be removed, and by pressing the battery case that is easily expanded due to the injection of the electrode active material, one region and another region in the battery case 10 become the shapes of the positive electrode and the negative electrode, respectively. In addition, through the calendering process, the positive electrode and the negative electrode may be in close contact with each other while being separated by the separator, and therefore, lithium ions may be smoothly exchanged.

[0128] In addition, the method for producing a lithium secondary battery of the present invention is preferred because it can produce the positive electrode and the negative electrode simultaneously through the above-mentioned rolling step without producing them separately, thereby simplifying the battery production process.

[0129] The pressure applied during calendering can be 400kgf / cm 2 Up to 600kgf / cm 2 , preferably 450kgf / cm 2 Up to 550kgf / cm 2 When the pressure is within the above range, a battery with high energy density can be manufactured without damaging the electrode active material.

[0130] The calendering process may be performed for 2 seconds to 60 seconds, preferably 3 seconds to 30 seconds, and more preferably 5 seconds to 10 seconds, which is preferred because the calendering process can be performed smoothly without damaging the electrode active material.

[0131] The method of manufacturing a lithium secondary battery of the present invention may further include drying the battery case 10 injected with the first mixture 20a and the second mixture 30a. Specifically, the first mixture 20a and the second mixture 30a may be dried by heating the inside of the battery case 10 injected with the first mixture 20a and the second mixture 30a.

[0132] The drying may be performed at 65°C to 90°C, and preferably at 75°C to 85°C.

[0133] The drying may be performed before calendering or simultaneously with calendering. In particular, it is preferred that calendering and drying be performed simultaneously because the process can be further simplified.

[0134] Specifically, when the first mixture 20a and the second mixture 30a in powder form are injected into the battery case 10, drying can be performed before calendering or simultaneously with calendering, and preferably simultaneously with calendering. That is, when the first mixture 20a and the second mixture 30a in powder form are injected, the time required for drying can be reduced, thereby drying and calendering can be completed simultaneously. Specifically, when the first mixture 20a and the second mixture 30a in powder form are injected, drying can be performed for 2 seconds to 60 seconds, preferably 3 seconds to 30 seconds, and more preferably 5 seconds to 10 seconds.

[0135] On the other hand, when the first mixture 20a and the second mixture 30a in the form of slurry are injected into the battery case 10, in consideration of ensuring sufficient drying time, drying may be performed before calendering. Specifically, when the first mixture 20a and the second mixture 30a are injected in the form of slurry, in order to fully dry the first mixture 20a and the second mixture 30a, drying may be performed for 5 minutes to 30 minutes, preferably 7 minutes to 15 minutes.

[0136] The method of manufacturing a lithium secondary battery of the present invention may further include injecting an electrolyte into the interior of the rolled battery case 10. Other details about the electrolyte have been described above.

[0137] The method of manufacturing a lithium secondary battery of the present invention may further include sealing the battery case 10 injected with the electrolyte.

[0138] Specifically, the sealing may include evacuating the interior of the battery case 10 injected with the electrolyte, whereby bubbles or pores inside the battery case 10 may be effectively removed to improve energy density.

[0139] Hereinafter, the present invention will be described in detail with reference to embodiments so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in many different forms, and therefore, the present invention is not limited to the embodiments described herein.

[0140] Example

[0141] Example 1: Production of lithium secondary battery

[0142] An aluminum pouch type battery case was provided. A polypropylene separator (15 μm in thickness) was formed in the battery case to partition the inside of the battery case into one region and another region.

[0143] LiNi as the positive electrode active material was mixed in a weight ratio of 90:5:5 0.8 Co 0.1 Mn 0.1 O2(average particle size(D 50 ): 12 μm), spherical aluminum particles as positive electrode current collector particles (average particle size (D 50 ): 2 μm) and acetylene black as a conductive material to prepare a first mixture in a powder form.

[0144] Artificial graphite (average particle size (D 50 ): 18 μm), copper particles as negative electrode current collector particles (average particle size (D 50 ): 2 μm) and acetylene black as a conductive material to prepare a second mixture in a powder form.

[0145] The first mixture and the second mixture were injected into one area and another area inside the battery case, respectively. During the injection, the battery case was vibrated at a frequency of 30 Hz.

[0146] After the first and second mixtures were injected, the battery case was rolled and dried simultaneously to produce a positive electrode and a negative electrode. 2 The calendering was performed under surface pressure of , and the drying was performed at 80° C., and the calendering and drying were performed for 7 seconds.

[0147] After that, the electrolyte is injected into the interior of the battery case, and the battery case is sealed by evacuating the interior of the case to manufacture a lithium secondary battery. The electrolyte is prepared by dissolving LiPF6 in a solvent prepared by mixing ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) in a volume ratio of 30:40:30 so that the LiPF6 concentration becomes 1M.

[0148] According to the lithium secondary battery manufactured in this way, the thickness of the positive electrode was 130 μm, and the thickness of the negative electrode was 145 μm. In addition, the porosity of the positive electrode was 25%, and the porosity of the negative electrode was 30%.

[0149] Example 2: Production of lithium secondary battery

[0150] A lithium secondary battery was manufactured in the same manner as in Example 1, except that LiNi was used as a positive electrode active material by mixing at a weight ratio of 93:2:5. 0.8 Co 0.1 Mn 0.1 O2(average particle size(D 50 ): 12 μm), spherical aluminum particles as positive electrode current collector particles (average particle size (D 50 ):2 μm) and acetylene black as a conductive material (powder form), and artificial graphite (average particle size (D 50 ): 18 μm), copper particles as negative electrode current collector particles (average particle size (D 50 ): 2 μm) and acetylene black as a conductive material (in powder form).

[0151] In this case, the porosity of the positive electrode is 26%, and the porosity of the negative electrode is 31%.

[0152] Example 3: Production of lithium secondary battery

[0153] A lithium secondary battery was manufactured in the same manner as in Example 1, except that LiNi was used as a positive electrode active material by mixing at a weight ratio of 83:12:5. 0.8 Co 0.1 Mn 0.1 O2(average particle size(D 50 ): 12 μm), spherical aluminum particles as positive electrode current collector particles (average particle size (D 50 ):2 μm) and acetylene black as a conductive material (powder form), and artificial graphite (average particle size (D 50 ): 18 μm), copper particles as negative electrode current collector particles (average particle size (D 50 ): 2 μm) and acetylene black as a conductive material (in powder form).

[0154] In this case, the porosity of the positive electrode is 23%, and the porosity of the negative electrode is 29%.

[0155] Example 4: Production of lithium secondary battery

[0156] A lithium secondary battery was manufactured in the same manner as in Example 1, except that when preparing the first mixture, LiNi as the first positive electrode active material was mixed at a weight ratio of 80:20. 0.8 Co 0.1 Mn 0.1 O2(average particle size(D 50 ): 14 μm) and LiNi as the second positive electrode active material 0.8 Co 0.1 Mn 0.1 O2(average particle size(D 50 ): 4 μm) and prepared positive electrode active material.

[0157] In this case, the porosity of the positive electrode is 24%, and the porosity of the negative electrode is 29%.

[0158] Comparative Example 1: Production of lithium secondary battery

[0159] LiNi as the positive electrode active material was mixed in N-methylpyrrolidone solvent at a weight ratio of 90:5:5 0.8 Co 0.1 Mn 0.1 O2(average particle size(D 50 ): 12 μm), acetylene black as a conductive material and polyvinylidene fluoride (PVDF) as a binder to prepare a positive electrode slurry, and the slurry is applied to one surface of an aluminum current collector (thickness: 15 μm), dried at 130° C., and then rolled to form a positive electrode. In this case, the thickness of the positive electrode is 130 μm.

[0160] Artificial graphite (average particle size (D 50 ): 18 μm), acetylene black as a conductive material and PVDF as a binder to prepare a negative electrode slurry, and the slurry is applied to one surface of a copper current collector layer (thickness: 15 μm), dried at 80° C., and then rolled to form a negative electrode. In this case, the thickness of the negative electrode is 145 μm.

[0161] A polypropylene separator (thickness: 15 μm) was inserted between the positive electrode and the negative electrode for the manufactured secondary battery to prepare an electrode assembly, the electrode assembly was placed in an aluminum bag-type battery case, and then an electrolyte was injected into the interior of the battery case to prepare a lithium secondary battery. The electrolyte was prepared by dissolving LiPF6 in a solvent prepared by mixing EC, DMC and EMC at a volume ratio of 30:40:30 so that the LiPF6 concentration became 1M.

[0162] In this case, the porosity of the positive electrode is 25%, and the porosity of the negative electrode is 30%.

[0163] Experimental example

[0164] Experimental Example 1: Output Characteristics Evaluation

[0165] The output characteristics of the lithium secondary batteries manufactured in Examples 1 to 4 and Comparative Example 1 were evaluated. According to the evaluation of the output characteristics, the lithium secondary batteries of Examples 1 to 4 and Comparative Example 1 were charged (0.2C CC / CV charge 4.2V 0.05C cutoff), allowed to stand for 10 minutes, and then discharged (0.2C CC discharge 2.5V cutoff).

[0166] In this case, the resistance (DCIR) was calculated by dividing the change between the voltage measured during the standing period and the voltage measured 60 seconds after the start of discharge by the change in current, and the results are shown in Table 1 below.

[0167] [Table 1]

[0168] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 DCIR(Ω) 24 29 25 21 42

[0169] Referring to Table 1, in the case of the lithium secondary batteries of Examples 1 to 4, it was evaluated that since a current collector in the form of particles was used, the current collector particles were uniformly distributed in the electrode active material, resulting in low resistance and excellent output characteristics.

[0170] On the other hand, in the case of the lithium secondary battery of Comparative Example 1, it can be seen that since a collector layer is provided at the bottom of the positive electrode or the negative electrode, the distance between the electrode active material existing on the upper part of the electrode active material layer and the collector layer increases, resulting in reduced output characteristics.

[0171] Experimental Example 2: Evaluation of Capacity Characteristics

[0172] The lithium secondary batteries manufactured in Examples 1 to 4 and Comparative Example 1 were initially charged (0.2C CC / CV charge 4.2V / 0.05C cutoff) and discharged (0.2C CC discharge 2.5V cutoff), and then their discharge capacities were evaluated.

[0173] The results are shown in Table 2 below.

[0174] [Table 2]

[0175]

[0176] Referring to Table 2, it can be seen that Examples 1 to 4 using a current collector in the form of particles achieve high capacity at the same thickness, compared to Comparative Example 1 using a current collector in the form of a plate.

[0177] [Explanation of symbols]

[0178] 10: Battery shell 11: Separator

[0179] 12a: positive electrode tab 12b: negative electrode tab

[0180] 20: positive electrode 20a: first mixture

[0181] 30: negative electrode 30a: second mixture

Claims

1. A lithium secondary battery, wherein the lithium secondary battery uses collector particles instead of plate-shaped collectors as collectors, The lithium secondary battery comprises: A battery case, the interior of which is divided into one area and another area by a separator; a positive electrode formed in the one region inside the battery case and comprising a positive electrode active material and positive electrode current collector particles; and a negative electrode formed in the other region inside the battery case and comprising a negative electrode active material and negative electrode current collector particles, in, The positive electrode comprises 1 to 15 wt % of the positive electrode current collector particles, and the negative electrode comprises 1 to 15 wt % of the negative electrode current collector particles, The porosity of the positive electrode is 20% to 30%, and the porosity of the negative electrode is 25% to 35%.

2. The lithium secondary battery according to claim 1, wherein The positive electrode current collector particles and the negative electrode current collector particles each independently have an average particle size D of 0.5 μm to 3 μm. 50 .

3. The lithium secondary battery according to claim 1, wherein The positive electrode current collector particles and the negative electrode current collector particles each independently include at least one selected from the group consisting of aluminum, copper, stainless steel, nickel, and titanium.

4. The lithium secondary battery according to claim 1, wherein The positive electrode active material comprises a first positive electrode active material and a second positive electrode active material, Among them, the average particle size D of the first positive electrode active material 50 Larger than the second positive electrode active material.

5. The lithium secondary battery according to claim 4, wherein: The average particle size D of the first positive electrode active material 50 The average particle size D of the second positive electrode active material is 10 μm to 18 μm. 50 2μm to 8μm.

6. A method for manufacturing the lithium secondary battery of claim 1, comprising: providing a battery case, the interior of which is divided into one area and another area by a separator; preparing a first mixture comprising a positive electrode active material and positive electrode current collector particles, and preparing a second mixture comprising a negative electrode active material and negative electrode current collector particles; injecting the first mixture into the one region inside the battery case, and injecting the second mixture into the other region inside the battery case; as well as The battery case injected with the first mixture and the second mixture is rolled while applying pressure.

7. The method according to claim 6, wherein: The first mixture and the second mixture are each independently injected into the battery case in the form of slurry or powder.

8. The method according to claim 6, wherein: During the injection of the first mixture and the second mixture, a step of vibrating the battery case is further performed. 9 . The method according to claim 6 , further comprising drying the battery case injected with the first mixture and the second mixture.

10. The method according to claim 9, wherein: The drying is performed before the calendering or simultaneously with the calendering.

11. The method according to claim 6, further comprising injecting an electrolyte into the interior of the battery case that has been calendared.

12. The method according to claim 11, further comprising: The battery case injected with the electrolyte is sealed by evacuating the interior of the battery case.

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