Negative electrode for lithium secondary battery and manufacturing method therefor

Abstract

The present invention relates to a negative electrode for a lithium secondary battery and a manufacturing method therefor, wherein the negative electrode includes a predetermined content of a silicon-based negative electrode active material in a first negative electrode active layer in contact with a negative electrode current collector, and has, by the adjustment of an alignment degree of the first negative electrode active layer (O.I1st) and a ratio of the alignment degree of the first negative electrode active layer to the alignment degree of a second negative electrode active layer (O.I1st / O.I2nd) to within predetermined ranges, not only high charge / discharge capacity but also excellent adhesion between the negative electrode current collector and the negative electrode active layer. In addition, a lithium secondary battery including the negative electrode may have excellent lifespan characteristics and output characteristics, and can be charged in a short time even at a 1C-rate.

Description

Anode for lithium secondary battery and method for manufacturing the same

[0001] The present invention relates to a negative electrode for a lithium secondary battery and a method for manufacturing the same.

[0002] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2023-0105354, dated August 11, 2023, and all contents of the document in that Korean patent application are incorporated herein by reference.

[0003]

[0004] Lithium secondary batteries are now widely used not only in small devices like portable electronic devices, but also in medium- to large-sized devices like battery packs for hybrid and electric vehicles and power storage systems. In particular, with growing concern over environmental issues, research is being conducted on electric vehicles and hybrid electric vehicles as alternatives to fossil fuel-powered vehicles like gasoline and diesel, which are major contributors to air pollution.

[0005] Due to their limited energy density, existing lithium secondary batteries are limited to short-range electric vehicles. Therefore, technology development has focused on further increasing the energy density of lithium secondary batteries.

[0006] However, developed lithium secondary batteries for automobiles suffer from the problem of requiring a long time to recharge after discharging during driving. Consequently, as the adoption of electric vehicles increases, demand is growing for shorter charging times to a level acceptable to users.

[0007] Meanwhile, lithium secondary batteries are rechargeable power generation devices composed of a stacked structure of anode / separator / cathode. When charging a lithium secondary battery, a lithium desorption reaction occurs at the cathode, where lithium contained in the cathode active material is oxidized and released, and a lithium insertion reaction occurs at the anode, where lithium is reduced and inserted into the cathode active material. Generally, the desorption reaction in the cathode active material is faster than the insertion reaction in the anode active material, so the rapid charge / discharge performance of a lithium secondary battery is primarily determined by the cathode.

[0008] Materials containing graphite are widely used as negative electrode active materials. The average potential when a material containing graphite releases lithium is approximately 0.2 V (Li / Li + ) and the discharge potential shows a relatively flat pattern. Therefore, when graphite is used as an anode active material, the voltage of the secondary battery has the advantage of being high and constant. However, the electrical capacity per unit mass of the graphite material is small at 372 mAh / g. On the other hand, since the capacity of the current graphite material has been improved to be close to the theoretical capacity, further capacity increase is difficult. In addition, when graphite is used as an anode active material, the lithium ion insertion reaction proceeds at a slow rate, so there is a limitation that the rapid charging performance is low compared to cases where other anode active materials are applied.

[0009] Accordingly, various anode active materials are being studied to improve the high capacity and rapid charging performance of lithium secondary batteries. For example, silicon has recently been widely studied as it has become known that it can reversibly adsorb and release large amounts of lithium through a compound formation reaction with lithium. Silicon has a theoretical maximum capacity of approximately 4020 mAh / g (9800 mAh / cc, specific gravity 2.23), which is much higher than that of graphite-based materials, making it useful as a high-energy density and / or high-capacity anode material. However, silicon not only induces a large volume change (~300%) during charge and discharge, but also exhibits low high-rate discharge characteristics. Accordingly, anode active layers containing silicon not only have low adhesion to the current collector, but also deteriorate quickly, and have limitations such as low efficiency during rapid charge and discharge.

[0010] Therefore, in order to fundamentally solve these problems, there is a high need for a cathode technology that has excellent rapid charge / discharge performance, excellent adhesion between the cathode active layer and the current collector, and can implement long life characteristics.

[0011]

[0012] [Prior Art Literature]

[0013] Republic of Korea Patent Publication No. 10-2020-0047287

[0014]

[0015] The purpose of the present invention is to provide a negative electrode for a lithium secondary battery having excellent high rapid charge / discharge performance, excellent adhesion between a negative electrode active layer and a current collector, and high life characteristics, and a method for manufacturing the same.

[0016]

[0017] To solve the above-mentioned problem,

[0018] The present invention,

[0019] negative current collector,

[0020] A first negative electrode active layer provided on at least one surface of the negative electrode current collector and containing a first carbon-based negative electrode active material and a silicon-based negative electrode active material, and

[0021] A second negative electrode active layer is provided on the first negative electrode active layer and contains a second carbon-based negative electrode active material;

[0022] The above first cathode active layer is,

[0023] The alignment (OI) is expressed by the following equation 1 1st ) ranges from 5 to 15,

[0024] Provided is a cathode satisfying the following equation 2 in a range of greater than 0.6 and less than 1.5:

[0025] [Formula 1]

[0026] OI = I 004 / I 110

[0027] [Formula 2]

[0028] OI 1st / OI 2nd

[0029] In equations 1 and 2,

[0030] I 004 represents the area of ​​the peak representing the (004) crystal plane of the carbon-based negative electrode material in the X-ray diffraction (XRD) spectroscopy analysis of the negative electrode active layer,

[0031] I 110 represents the area of ​​the peak representing the (110) crystal plane of the carbon-based negative electrode material in the X-ray diffraction (XRD)0 spectroscopy analysis of the negative electrode active layer,

[0032] OI 1st represents the alignment of the first carbon-based negative electrode active material contained in the first negative electrode active layer,

[0033] OI 2nd It shows the alignment degree of the second carbon-based negative electrode active material contained in the second negative electrode active layer.

[0034] At this time, the silicon-based negative electrode active material may be included in an amount of more than 0 wt% and less than 15 wt% based on the weight of the first negative electrode active layer.

[0035] Additionally, the first cathode active layer may have an alignment index (OI) in the range of 7 to 12.

[0036] In addition, the average particle diameter (D) of the first carbon-based negative electrode active material and the second carbon-based negative electrode active material 50 ) are each in the range of 1㎛ to 30㎛, and the average particle diameter (D) of the silicon-based negative electrode active material 50 ) can range from 0.5㎛ to 20㎛.

[0037] Additionally, the first cathode active layer and the second cathode active layer may each have a porosity in the range of 20% to 30%.

[0038] In addition, the first carbon-based negative electrode active material and the second carbon-based negative electrode active material may each include at least one of natural graphite and artificial graphite.

[0039] In addition, the silicon-based negative electrode active material is silicon (Si), silicon carbide (SiC), and silicon oxide (SiO). q , but may include one or more of the following (0.8≤q≤2.5).

[0040] In addition, the total loading amount of the first cathode active layer and the second cathode active layer may be in the range of 0.5 to 20 mg / cm2.

[0041]

[0042] In addition, the present invention,

[0043] A step of applying a negative electrode slurry to at least one surface of a negative electrode collector;

[0044] A step of applying a magnetic field to the applied cathode slurry; and

[0045] The present invention provides a method for manufacturing a cathode, comprising a step of drying a cathode slurry to which a magnetic field is applied to form a cathode active layer.

[0046] At this time, the step of applying the magnetic field can be performed for 1 to 20 seconds.

[0047] Additionally, the step of applying the magnetic field can be performed with a magnetic field strength ranging from 1,000 G to 7,000 G.

[0048]

[0049] Furthermore, the present invention,

[0050] An electrode assembly comprising an anode, a cathode according to the present invention, and a separator disposed between the anode and the cathode; and

[0051] A lithium secondary battery comprising an electrolyte composition in which the electrode assembly is impregnated is provided.

[0052] At this time, the positive electrode may include a positive electrode active layer provided on at least one surface of the positive electrode current collector and including at least one type of positive electrode active material among lithium metal oxides represented by the following chemical formulas 1 and 2:

[0053] [Chemical Formula 1]

[0054] Li x [Ni y Co z Mn w M 1 v ]O2

[0055] [Chemical Formula 2]

[0056] LiM 2 p Mn 1-p O4

[0057] In the above chemical formulas 1 and 2,

[0058] M 1 is W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo and one or more elements,

[0059] x, y, z, w and v are 1.0≤x≤1.30, 0.5≤y<1, 0 respectively <z≤0.3, 0<w≤0.3, 0≤v≤0.1이되, y+z+w+v=1이고,

[0060] M 2 is Ni, Co or Fe,

[0061] p is 0.05≤p≤1.0.

[0062] Specifically, the positive electrode active material is LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.9 Co 0.05 Mn 0.05 O2, LiNi 0.6 Co 0.2 Mn 0.1 Al 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.15 Al 0.05 O2, LiNi 0.7 Co 0.1 Mn 0.1 Al 0.1 O2, LiNi 0.7 Mn 1.3 O4, LiNi 0.5 Mn 1.5 O4 and LiNi 0.3 Mn 1.7 It may contain one or more of O4.

[0063] The above electrode assembly may be a stacked electrode assembly; a zigzag electrode assembly; or a zigzag-stacked electrode assembly.

[0064]

[0065] The anode for a lithium secondary battery according to the present invention not only has a high charge / discharge capacity but also exhibits excellent adhesion between the anode current collector and the anode active layer. Furthermore, a lithium secondary battery comprising the anode current collector exhibits excellent output characteristics and has the advantage of being able to be charged in a short time even at a 1C rate.

[0066]

[0067] The present invention can be modified in various ways and has many embodiments, and specific embodiments will be described in detail in the detailed description.

[0068] However, this is not intended to limit the present invention to a specific embodiment, but should be understood to include all modifications, equivalents, or substitutes included in the technical scope of the present invention.

[0069] In the present invention, it should be understood that terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0070] Additionally, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only cases where it is "directly above" the other part, but also cases where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only cases where it is "directly below" the other part, but also cases where there is another part in between. Furthermore, in the present application, "on" may include cases where it is placed below as well as above.

[0071] In addition, in the present invention, "comprising as a main component" may mean comprising a defined component at 50 wt% or more (or 50 vol% or more), 60 wt% or more (or 60 vol% or more), 70 wt% or more (or 70 vol% or more), 80 wt% or more (or 80 vol% or more), 90 wt% or more (or 90 vol% or more), or 95 wt% or more (or 95 vol% or more) of the total weight (or total volume). For example, "comprising graphite as a main component as a negative electrode active material" may mean comprising graphite at 50 wt% or more, 60 wt% or more, 70 wt% or more, 80 wt% or more, 90 wt% or more, or 95 wt% or more of the total weight of the negative electrode active material, and in some cases, it may mean that the entire negative electrode active material is made of graphite and comprises 100 wt% of graphite.

[0072] In addition, in the present specification, “the carbon-based negative electrode active material is oriented” or “the carbon-based negative electrode active material is aligned” means that a specific crystal plane (e.g., the ab-axis crystal plane of graphite) representing a two-dimensional planar structure of the carbon-based negative electrode active material constituting the negative electrode active material particles is arranged to have a predetermined inclination with respect to the negative electrode current collector surface, which may be different from the case where the carbon-based negative electrode active material particles themselves are arranged to have a specific direction within the negative electrode active layer.

[0073] In addition, "the carbon-based negative electrode active material has a high degree of orientation" may mean that a specific crystal plane (e.g., an ab-axis crystal plane of graphite) representing a two-dimensional planar structure of the carbon-based negative electrode active material contained in the negative electrode active layer frequently has a predetermined inclination with respect to the surface of the negative electrode current collector. Furthermore, in some cases, it may mean that the crystal plane of the carbon-based negative electrode active material contained in the negative electrode active layer is arranged at a high angle (e.g., an angle close to vertical, exceeding 45°; specifically, 60° or more) with respect to the surface of the negative electrode current collector.

[0074] In addition, the "degree of alignment of the carbon-based negative electrode active material is high" means that the "degree of alignment (OI)" mentioned herein has a large value, which may mean that a specific crystal plane (e.g., an ab-axis crystal plane of graphite) representing a two-dimensional planar structure of the carbon-based negative electrode active material contained in the negative electrode active layer is aligned at a low angle (e.g., less than 45°) with respect to the surface of the negative electrode current collector. Conversely, the "degree of alignment of the carbon-based negative electrode active material is low" means that the "degree of alignment (OI)" has a small value, which may mean that the crystal plane of the carbon-based negative electrode active material contained in the negative electrode active layer is aligned at a high angle (e.g., an angle close to vertical, 45° or more; specifically, 60° or more) with respect to the surface of the negative electrode current collector.

[0075] Furthermore, in this specification, the “crystal plane of the carbon-based negative electrode active material” refers to a plane where atoms of the carbon-based negative electrode active material form the outer shape of the crystal, and in the present invention, it may mean a crystal plane including a plane of the carbon-based negative electrode active material, or a crystal plane including the a-axis / b-axis / ab-axis of the carbon-based negative electrode active material crystal.

[0076] Also, in this specification, "average particle diameter (D 50 )" refers to the particle size at which the accumulated value is 50% in the particle size distribution, and is also called the median diameter.

[0077]

[0078] Hereinafter, the present invention will be described in more detail.

[0079]

[0080] Cathode for lithium secondary batteries

[0081] The present invention,

[0082] negative current collector,

[0083] A first negative electrode active layer provided on at least one surface of the negative electrode current collector and containing a first carbon-based negative electrode active material and a silicon-based negative electrode active material, and

[0084] A second negative electrode active layer is provided on the first negative electrode active layer and contains a second carbon-based negative electrode active material;

[0085] The above first cathode active layer is,

[0086] The alignment (OI) is expressed by the following equation 1 1st ) ranges from 5 to 15,

[0087] Provided is a cathode satisfying the following equation 2 in a range of greater than 0.6 and less than 1.5:

[0088] [Formula 1]

[0089] OI = I 004 / I 110

[0090] [Formula 2]

[0091] OI 1st / OI 2nd

[0092] In equations 1 and 2,

[0093] I 004 represents the area of ​​the peak representing the (004) crystal plane of the carbon-based negative electrode material in the X-ray diffraction (XRD) spectroscopy analysis of the negative electrode active layer,

[0094] I 110 represents the area of ​​the peak representing the (110) crystal plane of the carbon-based negative electrode material in the X-ray diffraction (XRD)0 spectroscopy analysis of the negative electrode active layer,

[0095] OI 1st represents the alignment of the first carbon-based negative electrode active material contained in the first negative electrode active layer,

[0096] OI 2nd It shows the alignment degree of the second carbon-based negative electrode active material contained in the second negative electrode active layer.

[0097]

[0098] The negative electrode for a lithium secondary battery according to the present invention includes a negative electrode active layer on at least one surface of a negative electrode current collector. The negative electrode active layer is a layer that implements electrical activity of the negative electrode, and includes as a main component a negative electrode active material that implements an electrochemical redox reaction during charging and discharging of the battery. The negative electrode active material includes a carbon-based negative electrode active material and a silicon-based negative electrode active material.

[0099] Here, the carbon-based negative electrode active material refers to a material whose main component is carbon atoms. Such carbon-based negative electrode active materials may include graphite.

[0100] The above graphite may include at least one of natural graphite and artificial graphite. In addition to natural graphite and artificial graphite, the graphite may further include mesophase calcined carbon (bulk mesophase) made from tar or pitch, and graphitized coke (raw coke, green coke, pitch coke, needle coke, petroleum coke, etc.).

[0101] For example, the cathode active layer according to the present invention may solely comprise artificial graphite. The present invention, by including artificial graphite solely in the cathode active layer, significantly improves the lifespan of the cathode, which can be advantageous in conditions such as automobile batteries that must withstand frequent charging for long periods of time. Furthermore, artificial graphite offers the advantages of rapid charging and superior output performance compared to natural graphite.

[0102] In addition, the negative electrode active layer according to the present invention may include both natural graphite and artificial graphite, in which case the mixing ratio of natural graphite and artificial graphite may be 5 to 50 wt%:50 to 95 wt%, 20 to 45 wt%:55 to 80 wt%, or 5 to 15 wt%:85 to 95 wt% based on weight. The present invention can maintain a high rapid charging speed and output performance by including both natural graphite and artificial graphite in the negative electrode active layer at the above content ratio. In addition, it can prevent the adhesive force between the negative electrode current collector and the negative electrode active layer from being reduced due to a large volume change of the silicon-based negative electrode active material during charge and discharge.

[0103] In addition, the carbon-based negative electrode active material may have a round particle shape rather than a plate-like, sheet-like, flake-like, or needle-like shape. Here, a round particle shape may mean a particle without a sharp edge. When performing a cross-sectional structural analysis of such particles or projecting them into two-dimensional particles, the shape may be spherical or ellipsoidal, and in some cases, it may be an amorphous shape (shapelessness) that is difficult to define.

[0104] For example, the carbon-based negative electrode active material may be graphite having a spherical particle shape. At this time, the spherical particles may be processed to have a spherical shape / form during manufacturing, or may be spherical graphite aggregates formed by aggregating a plurality of flake-shaped graphite. When the spherical particles are the aggregates, one graphite aggregate may be formed by aggregating 2 to 100, preferably 3 to 20, flake-shaped graphite. The present invention can further increase the electrical conductivity of the negative electrode active layer by controlling the shape of the carbon-based negative electrode active material as described above, and can improve the adhesive strength between the negative electrode active layer and the negative electrode current collector by maximizing the contact area with the negative electrode current collector.

[0105] Additionally, the carbon-based negative electrode active material may be spheroidal. In this case, the carbon-based negative electrode active material can more easily secure a path for lithium ions to move within the negative electrode active layer, thereby enabling charging to be completed in a shorter time even under the same conditions.

[0106] Furthermore, the size of the carbon-based negative electrode active material can be controlled within a certain range. Specifically, the average particle diameter (D) of the carbon-based negative electrode active material 50 ) may be in the range of 1 ㎛ to 30 ㎛, and specifically, may be in the range of 1 ㎛ to 20 ㎛; 1 ㎛ to 15 ㎛; 1 ㎛ to 10 ㎛; 1 ㎛ to 8 ㎛; 1 ㎛ to 5 ㎛; 1 ㎛ to 3 ㎛; 10 ㎛ to 20 ㎛; 11 ㎛ to 19 ㎛; 8 ㎛ to 15 ㎛; 15 ㎛ to 20 ㎛; 13 ㎛ to 19 ㎛; 14 ㎛ to 17 ㎛; 5 ㎛ to 8 ㎛; 7 ㎛ to 14 ㎛; 9 ㎛ to 13 ㎛; 2 ㎛ to 6 ㎛; 5 ㎛ to 9 ㎛; 1 ㎛ to 4.5 ㎛; or 1 ㎛ to 3 ㎛.

[0107] The present invention can easily suppress an increase in the electrical resistance of the negative electrode active layer by controlling the average particle diameter of the carbon-based negative electrode active material within the above range. In addition, within the above average particle diameter range, the carbon-based negative electrode active material can maximize the degree of disorder in the direction of expansion of each particle to prevent expansion of the particles due to lithium ion charging while increasing the specific surface area per unit weight, thereby further enhancing the adhesive strength between the negative electrode active layer and the negative electrode current collector. In addition, the carbon-based negative electrode active material can secure a movement path of lithium ions within the above average particle diameter range, so that the rapid charging performance is further improved. On the other hand, the carbon-based negative electrode active material has the advantage of further improving the rapid charging performance because the average particle diameter (D 50 ) has a particle diameter lower than the lower limit, a large amount of binder is required due to an increase in the number of particles per unit volume, which may deteriorate the electrical properties of the negative electrode active layer containing them. On the other hand, if the average particle diameter (D 50) has a high particle size exceeding the upper limit, the expansion rate of the negative electrode active material increases significantly during charging and discharging of the secondary battery, so that as charging and discharging are repeated, the adhesion between the negative electrode active material particles and the adhesion between the negative electrode active material particles and the current collector deteriorates, which may significantly reduce the cycle characteristics.

[0108] In addition, the silicon-based negative electrode active material refers to a material whose main component is silicon atoms. Such silicon-based negative electrode active materials include silicon (Si), silicon carbide (SiC), silicon monoxide (SiO), or silicon dioxide (SiO2), and these may be included alone or in combination in the negative electrode active layer. When silicon monoxide (SiO2) and silicon dioxide (SiO2) are uniformly mixed or composited and included in the negative electrode active layer as the silicon-based negative electrode active materials, they are silicon oxide (SiO2). q , but can be expressed as 0.8≤q≤2.5).

[0109] In addition, the silicon-based negative electrode active material may be doped with Li, Mg, Al, Ca, or Ti, or may form an alloy. In addition, the silicon-based negative electrode active material may be surface-treated with a carbon coating layer or the like to suppress volume expansion during charging and improve electrical conductivity of the negative electrode active material when containing oxygen (O).

[0110] In addition, the size of the silicon-based negative electrode active material can be controlled within a certain range. Specifically, the average particle diameter (D) of the silicon-based negative electrode active material 50) may be in the range of 0.5 μm to 20 μm, and specifically, may be in the range of 0.5 μm to 15 μm; 0.5 μm to 13 μm; 0.5 μm to 9 μm; 0.5 μm to 6 μm; 0.5 μm to 4 μm; 0.5 μm to 2 μm; 9 μm to 18 μm; 10 μm to 17 μm; 7 μm to 14 μm; 14 μm to 18 μm; 12 μm to 18 μm; 11 μm to 15 μm; 4 μm to 8 μm; 4 μm to 13 μm; 5 μm to 12 μm; 7 μm to 11 μm; 1 μm to 5 μm; 3 μm to 8 μm; 1 μm to 3 μm; or 1 μm to 2 μm.

[0111] Meanwhile, the negative electrode active layer may have a two-layer structure in which a first negative electrode active layer and a second negative electrode active layer are sequentially laminated on a negative electrode current collector. Since the composition of each layer of the negative electrode active layer having a two-layer structure can be easily controlled, the performance of the negative electrode can be improved by controlling the type or content of components contained in each layer according to a specific purpose, such as increasing the energy efficiency of the battery or improving the adhesion between the active layer and the current collector. For example, the negative electrode active layer may selectively include a silicon-based negative electrode active material having a high charge / discharge capacity of the battery only in the first negative electrode active layer in contact with the negative electrode current collector. In addition, the negative electrode active layer may selectively include natural graphite having good adhesive properties as a negative electrode active material only in the first negative electrode active layer in contact with the negative electrode current collector, or may include a high content of a binder that provides binding properties to the components constituting the active layer.

[0112] In the present invention, the first negative electrode active layer includes a first carbon-based negative electrode active material and a silicon-based negative electrode active material, and the second negative electrode active layer includes a second carbon-based negative electrode active material. At this time, the first carbon-based negative electrode active material and the second carbon-based negative electrode active material included in each negative electrode active layer may be the same or different in type and / or content.

[0113] The present invention can improve the charge / discharge capacity of an anode by including a silicon-based anode active material in a first anode active layer in contact with an anode current collector. Furthermore, since a lithium migration path can be easily provided within the anode active layer, there is an advantage in that the charge / discharge time of a secondary battery can be reduced.

[0114] At this time, the silicon-based negative electrode active material may be included in a predetermined amount based on the total weight of the first negative electrode active layer. Specifically, the silicon-based negative electrode active material may be included in an amount of more than 0 wt% and less than 15 wt% based on the total weight of the first negative electrode active layer, and more specifically, may be included in an amount of 0.1 to 14 wt%; 0.1 to 12 wt%; 0.1 to 9 wt%; 0.1 to 8 wt%; 0.1 to 7 wt%; 0.1 to 6 wt%; 0.1 to 5 wt%; 0.5 to 8 wt%; 1 to 6 wt%; 1 to 5 wt%; 3 to 7 wt%; 7 to 13 wt%; 11 to 14 wt%; 3 to 12 wt%; 4 to 11 wt%; 0.5 to 3 wt%; or 2 to 6 wt%. The present invention can minimize the volume change rate due to the silicon-based negative electrode active material during charge and discharge by controlling the content ratio of the silicon-based negative electrode active material within the negative electrode active material within the above range. Accordingly, the negative electrode of the present invention can maintain a lithium migration path of the carbon-based negative electrode active material implemented within the negative electrode active layer due to the application of a magnetic field, thereby increasing the charge and discharge speed of the secondary battery. In addition, the negative electrode can minimize deterioration during charge and discharge, thereby improving the life characteristics of the secondary battery.

[0115] The cathode according to the present invention can control the crystal structure characteristics of the carbon-based cathode active materials contained in the cathode active layer to realize a fast charging speed. Specifically, the first cathode active layer can have an alignment degree (OI) of the carbon-based cathode active material in the range of 5 to 15 according to the following equation 1:

[0116] [Formula 1]

[0117] OI = I 004 / I 110

[0118] In equation 1,

[0119] I 004 represents the area of ​​the peak representing the [0,0,4] crystal plane of the carbon-based negative electrode material in the X-ray diffraction (XRD) spectroscopy analysis of the negative electrode active layer,

[0120] I 110 represents the area of ​​the peak representing the [1,1,0] crystal plane of the carbon-based negative electrode material in X-ray diffraction (XRD) spectroscopy analysis of the negative electrode active layer.

[0121]

[0122] The degree of alignment (OI) of the above carbon-based negative electrode active material can be an indicator of the degree to which the ab-axis crystal plane of the carbon-based negative electrode active material is oriented in a certain direction, specifically, with respect to the negative electrode current collector surface, when measured by X-ray diffraction (XRD). Specifically, the first negative electrode active layer exhibits peaks of 2θ=26.5±0.2°, 42.4±0.2°, 43.4±0.2°, 44.6±0.2°, 54.7±0.2°, and 77.5±0.2° for graphite, which is a carbon-based negative electrode active material, when measured by X-ray diffraction. This represents the (002) plane, (100) plane, (101)R plane, (101)H plane, (004) plane, and (110) plane of graphite. Here, the peak appearing at 2θ=43.4±0.2° can be seen as an overlap between the (101)R plane of the carbon-based negative electrode material and the peak corresponding to the (111) plane of a current collector, such as copper (Cu).

[0123] The degree of alignment (OI) of the carbon-based negative electrode material can be measured by measuring the ratio of the areas obtained by integrating the respective intensities of the peak at 2θ=54.7±0.2° representing the (004) plane and the peak at 2θ=77.5±0.2° representing the (110) plane.

[0124] The peak at 2θ=54.7±0.2° is a peak indicating a crystal plane having an inclination with respect to the negative electrode current collector among the crystal planes of the carbon-based negative electrode active material, so that the degree of alignment (OI) may mean that the closer the value is to 0, the closer the inclination with respect to the negative electrode current collector surface is to 90°, and the larger the value is, the closer the inclination with respect to the negative electrode current collector surface is to 0° or 180°. That is, the first negative electrode active layer according to the present invention may be aligned so that the first carbon-based negative electrode active material contained in the layer has an angle of 60° or more, 70° or more, 70 to 90°, 80 to 90°, 65 to 85°, or 70 to 85° with respect to the negative electrode current collector. Accordingly, the degree of alignment (OI) of the carbon-based negative electrode active material in the first negative electrode active layer may be lower compared to a case where the carbon-based negative electrode active material is aligned at a low angle of less than 60°. Here, the degree of alignment (OI) may indicate the degree to which the carbon-based negative electrode active material particles are aligned on the surface of the negative electrode current collector. In addition, in some cases, the degree of alignment (OI) may indicate the degree of alignment of the ab-axis crystal planes of the carbon-based negative electrode active material within the negative electrode active layer. When the ab-axis crystal planes of the carbon-based negative electrode active material are aligned, rotation of the particles of the carbon-based negative electrode active material contained in the negative electrode active layer may also be induced. However, since the particle rotation at this time is affected by the shape of the particle, it is not equivalent to the degree of alignment of the ab-axis crystal planes, and therefore it may be difficult for the degree of alignment (OI) to indicate that the particles of the carbon-based negative electrode active material are aligned.

[0125] Here, the first carbon-based negative electrode active material contained in the first negative electrode active layer may have an alignment index (OI) in the range of 5 to 15, and specifically, may have an OI in the range of 5 to 13; 5 to 11; 5 to 9; 6 to 14; 10 to 15; 6 to 13; 6.5 to 11; 7 to 12; 7.5 to 10; 6 to 9.5; 6 to 7; or 7.5 to 9.5.

[0126] If the degree of alignment (OI) of the first carbon-based negative electrode active material contained in the first negative electrode active layer is lower than the lower limit described above, the adhesive force with the negative electrode current collector may be reduced. Therefore, the present invention controls the degree of alignment (OI) of the first carbon-based negative electrode active material contained in the first negative electrode active layer to be higher than the lower limit described above, thereby increasing the ratio of the crystal planes of the first carbon-based negative electrode active material molecules constituting the negative electrode active material particles facing the negative electrode current collector, thereby improving the rapid charging performance of the negative electrode within a range where the adhesive force between the first negative electrode active layer and the negative electrode current collector is not reduced. In addition, the present invention provides a method for improving the degree of alignment (OI) of the first carbon-based negative electrode active material contained in the first negative electrode active layer. 1st ) can be adjusted to be below the upper limit described above, thereby securing an ion migration channel through which lithium ions can move more briefly within the negative electrode active layer. Accordingly, the negative electrode of the present invention can prevent an increase in resistance due to a long migration distance of lithium ions within the negative electrode active layer, thereby further increasing the migration speed of lithium ions during charging and discharging, thereby simultaneously improving rapid charging performance and output performance with high safety.

[0127] In addition, the first cathode active layer can satisfy Equation 2 in a range of greater than 0.6 and less than or equal to 1.5:

[0128] [Formula 2]

[0129] OI 1st / OI 2nd

[0130] In equation 2,

[0131] OI 1st represents the alignment of the first carbon-based negative electrode active material contained in the first negative electrode active layer,

[0132] OI 2nd It shows the alignment degree of the second carbon-based negative electrode active material contained in the second negative electrode active layer.

[0133]

[0134] The above equation 2 is the alignment degree (OI) of the first carbon-based negative electrode active material contained in the first negative electrode active layer. 1st ) and the alignment degree (OI) of the second carbon-based negative electrode active material contained in the second negative electrode active layer 2nd ) is shown as the ratio.

[0135] The first negative electrode active layer may include a silicon-based negative electrode active material together with a first carbon-based negative electrode active material, and may affect the alignment and / or orientation of the first carbon-based negative electrode active material when the first carbon-based negative electrode active material is aligned and / or aligned according to the application of a magnetic field. Accordingly, the first negative electrode active layer and the second negative electrode active layer may have an alignment ratio within a predetermined range to satisfy Equation 2. Specifically, the first negative electrode active layer may satisfy Equation 2 within a range of greater than 0.6 and less than or equal to 1.5. For example, the first negative electrode active layer may satisfy Equation 2 within a range of 0.61 to 1.5; 0.65 to 1.5; 0.65 to 1.4; 0.7 to 1.4; 0.7 to 1.2; 0.7 to 1.0; 0.7 to 0.9; 0.8 to 1.2; 1.0 to 1.2; 0.81 to 0.95; It can be satisfied with the range of 1.05 to 1.20; 0.81 to 1.15; or 0.9 to 1.1.

[0136] The first negative electrode active layer of the present invention can solidify the position of the silicon-based negative electrode active material between the aligned and / or oriented first carbon-based negative electrode active materials by satisfying the above-described formula 2 within the above-described range, thereby minimizing damage to the movement path of lithium formed within the negative electrode active layer due to volume change of the silicon-based negative electrode active material during charge and discharge. Accordingly, not only is the charging speed of the secondary battery improved even at a low C-rate of 1C, but the lifespan of the negative electrode can also be improved, thereby exhibiting excellent characteristics.

[0137] Specifically, conventional rapid charging of lithium secondary batteries has been applied to increase the speed by performing charging under high C-rate conditions exceeding the 1C-rate using the constant current-constant voltage (CC-CV) method. In general, constant current-constant voltage (CC-CV) charging inevitably causes concentration polarization due to the diffusion of lithium ions within the electrode during the constant current (CC) charging phase. This long-term diffusion inevitably causes concentration polarization. This concentration polarization of lithium ions easily causes lithium precipitation from the negative electrode, especially under high-rate conditions where the charging current (A) exceeds the standard value (i.e., the current at 1C-rate: 1A) compared to the rated capacity (Ah) of the secondary battery, which significantly lowers the safety of the secondary battery. In addition, high-rate constant current-constant voltage (CC-CV) charging reaches the upper limit voltage very quickly during the constant current (CC) charging phase, so the current may drop to a preset limit before the active material is completely consumed. That is, there is a problem that the effect of reducing the total time for charging a secondary battery is minimal because the charging time is significantly increased during the constant voltage (CV) charging stage.

[0138] However, the present invention can secure a short path for lithium ions to move in the negative electrode active layer, so that the resistance induced in the negative electrode active layer during charging can be significantly reduced. This resistance reduction can induce that the execution time of the constant current (CC) charging step is longer than the execution time of the constant voltage (CV) charging step during the total charging time when charging in the constant current-constant voltage (CC-CV) method. Here, since the same amount of current flows in the constant current (CC) charging step, the charge capacity per unit time is the same, but the constant voltage (CV) charging step shows a tendency for the current to be reduced in order to maintain the same voltage. In other words, since the charge capacity per unit time is rapidly reduced in the constant voltage (CV) charging step, the total charge time can be significantly reduced as the execution time of the constant current (CC) charging step increases. Therefore, the present invention relates to an alignment degree (OI) of a first carbon-based negative electrode active material in a first negative electrode active layer.1st ) and the alignment ratio (OI) of the first carbon-based negative electrode active material and the second carbon-based negative electrode active material 1st / OI 2nd ) can increase the execution time of the constant current (CC) charging step, thereby completing charging of the secondary battery in a significantly shorter time.

[0139] Furthermore, since rapid charging of these secondary batteries can be implemented under standard (e.g., 1 C-rate) conditions rather than high C-rate conditions, there is an advantage in overcoming the safety problem of lithium secondary batteries caused by the concentration polarization phenomenon of lithium ions induced in the negative electrode active layer during charging.

[0140]

[0141] Meanwhile, the loading amount of the first negative electrode active layer and the second negative electrode active layer can be adjusted within a predetermined range. Specifically, the total loading amount of the first negative electrode active layer and the second negative electrode active layer can be in the range of 0.5 to 20 mg / ㎠, and more specifically, it can be in the range of 0.5 to 17 mg / ㎠; 0.5 to 15 mg / ㎠; 0.5 to 12 mg / ㎠; 0.5 to 10 mg / ㎠; 1.0 to 7.5 mg / ㎠; 1.0 to 5.0 mg / ㎠; 1.0 to 3.0 mg / ㎠; 5 to 15 mg / ㎠; 10 to 18 mg / ㎠; or 13 mg / ㎠ or more and less than 20 mg / ㎠.

[0142] The present invention introduces a silicon-based negative electrode active material into a second negative electrode active layer adjacent to a positive electrode active layer, thereby improving the alignment (OI) of the second negative electrode active layer. 2nd ) is the alignment degree (OI) of the first cathode active layer 1st) appears relatively large. In this case, the shortening effect of the lithium movement path on the surface of the negative electrode active layer may be minimal. However, the present invention can shorten the lithium movement path so that lithium ions can easily access the inside of the negative electrode active layer, specifically, the negative electrode active layer region near the negative electrode current collector, during charge and discharge by controlling the loading amount of each negative electrode active layer within the above-described range. Accordingly, the negative electrode of the present invention has a characteristic that enables rapid charging that can complete charging in a short time even under standard conditions (1C-rate).

[0143] Additionally, the first cathode active layer and the second cathode active layer may each have a porosity in the range of 20% to 30%, specifically, a porosity in the range of 23% to 30%; 25% to 30%; 26% to 29%; or 24% to 28%.

[0144] In addition, the first cathode active layer and the second cathode active layer may exhibit a BET specific surface area in the range of 0.62 m2 / g or less, and specifically, may exhibit a BET specific surface area in the range of 0.615 m2 / g or less, 0.6 m2 / g or less, 0.5 m2 / g or less, 0.20 to 0.62 m2 / g, 0.30 to 0.62 m2 / g, 0.40 to 0.62 m2 / g, 0.40 to 0.60 m2 / g, 0.40 to 0.55 m2 / g, 0.40 to 0.50 m2 / g, or 0.58 to 0.62 m2 / g.

[0145] Here, the porosity and specific surface area can be measured using the BET (Brunauer-Emmett-Teller; BET) method. For example, the BET six-point method can be measured using a porosimetry analyzer (Bell Japan Inc, Belsorp-II mini) and a nitrogen gas adsorption flow method.

[0146] The present invention can further increase the energy density of the cathode without reducing the electrolyte wettability of each cathode active layer by controlling the porosity and BET specific surface area of ​​each cathode active layer within the above ranges.

[0147]

[0148] In addition, the negative electrode active layer according to the present invention may optionally further include a conductive material, a binder, other additives, etc., as needed, along with the negative electrode active material as the main component.

[0149] The above-mentioned challenge material may include one or more of carbon black, acetylene black, Ketjen black, carbon nanotubes, carbon fibers, etc., but is not limited thereto.

[0150] As an example, the cathode active layer may contain carbon black, carbon nanotubes, carbon fibers, etc. alone or in combination as a conductive material.

[0151] At this time, the content of the conductive material may be 0.1 to 10 parts by weight based on 100 parts by weight of the entire negative electrode active layer, and specifically, may be 0.1 to 8 parts by weight, 0.1 to 5 parts by weight, 0.1 to 3 parts by weight, 2 to 6 parts by weight, or 0.5 to 2 parts by weight. By controlling the content of the conductive material within the above range, the present invention can prevent the resistance of the negative electrode from increasing due to a low content of the conductive material, thereby reducing the charging capacity, and can prevent the problem of the content of the negative electrode active material decreasing due to an excessive amount of the conductive material, thereby reducing the charging capacity, or the problem of the rapid charging characteristics deteriorating due to an increase in the loading amount of the negative electrode active layer.

[0152] In addition, the binder may be appropriately applied as a component that assists in the bonding of the negative electrode active material and the conductive material and the bonding to the current collector, and may be applied within a range that does not deteriorate the electrical properties of the electrode. Specifically, the binder may include at least one selected from the group consisting of vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVdF), polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene butadiene rubber (SBR), and fluororubber.

[0153] The content of the binder may be 0.1 to 10 parts by weight based on 100 parts by weight of the entire negative electrode active layer, and specifically, may be 0.1 to 8 parts by weight, 0.1 to 5 parts by weight, 0.1 to 3 parts by weight, or 2 to 6 parts by weight. The present invention can prevent the adhesive strength of the active layer from being lowered due to a low content of binder or the electrical properties of the electrode from being lowered due to an excessive amount of binder by controlling the content of the binder contained in the negative electrode active layer within the above range.

[0154] In addition, the negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, nickel, titanium, calcined carbon, etc. can be used. In the case of copper or stainless steel, a material surface-treated with carbon, nickel, titanium, silver, etc. can also be used. In addition, the average thickness of the negative electrode current collector can be appropriately applied in the range of 1 to 500 ㎛ in consideration of the conductivity and total thickness of the negative electrode to be manufactured.

[0155]

[0156] lithium secondary battery

[0157] In addition, the present invention,

[0158] An electrode assembly comprising an anode, a cathode of the present invention described above, and a separator disposed between the anode and the cathode; and

[0159] A lithium secondary battery comprising an electrolyte composition in which the electrode assembly is impregnated is provided.

[0160]

[0161] A lithium secondary battery according to the present invention comprises an electrode assembly having a structure in which a plurality of positive electrodes and a plurality of negative electrodes are alternately arranged and a separator is positioned between them. The lithium secondary battery, which comprises the negative electrode of the present invention described above, has a large charge / discharge capacity and excellent lifespan characteristics, and can be charged in a short time even at a 1C-rate, so that it can be usefully used as a power source for medium- to large-sized devices such as electric vehicles.

[0162] At this time, since the cathode has the same configuration as the configuration described above, a detailed description is omitted.

[0163] In addition, the positive electrode includes a positive electrode active layer including a positive electrode active material on a positive electrode current collector, and the positive electrode active layer may optionally further include a conductive material, a binder, other additives, etc., as needed.

[0164] The above cathode active material is a material capable of causing an electrochemical reaction on the cathode current collector, and may include at least one lithium metal oxide represented by the following chemical formulas 1 and 2, which is capable of reversibly intercalating and deintercalating lithium ions:

[0165] [Chemical Formula 1]

[0166] Li x [Ni y Co z Mn w M 1v ]O2

[0167] [Chemical Formula 2]

[0168] LiM 2 p Mn q P r O4

[0169] In the above chemical formulas 1 and 2,

[0170] M 1 is at least one element among W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo,

[0171] x, y, z, w and v are 1.0≤x≤1.30, 0.5≤y<1, 0 respectively <z≤0.3, 0<w≤0.3, 0≤v≤0.1이되, y+z+w+v=1이고,

[0172] M 2 is Ni, Co or Fe,

[0173] p is 0.05≤p≤1.0,

[0174] q is 2-p,

[0175] r is either 0 or 1.

[0176]

[0177] The lithium metal oxides represented by the above chemical formulas 1 and 2 are substances containing high contents of nickel (Ni) and manganese (Mn), respectively, and when used as a cathode active material, they have the advantage of being able to stably supply electricity at a high capacity and / or high voltage compared to cathode active materials such as iron phosphate (LiFeO4) that are conventionally used.

[0178] At this time, the lithium metal oxide represented by the chemical formula 1 is LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.9Co 0.05 Mn 0.05 O2, LiNi 0.6 Co 0.2 Mn 0.1 Al 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.15 Al 0.05 O2, LiNi 0.7 Co 0.1 Mn 0.1 Al 0.1 It may include O2, etc., and the lithium metal oxide represented by the above chemical formula 2 is LiNi 0.7 Mn 1.3 O4; LiNi 0.5 Mn 1.5 O4; LiNi 0.3 Mn 1.7 It may include O4, etc., and these may be used alone or in combination.

[0179] In addition, the positive electrode active material may be included in an amount of 85 parts by weight or more based on 100 parts by weight of the positive electrode active layer, and specifically, may be included in an amount of 90 parts by weight or more, 93 parts by weight or more, or 95 parts by weight or more.

[0180] In addition, the positive electrode active layer may further include a conductive agent, a binder, other additives, etc., along with the positive electrode active material.

[0181] At this time, the conductive material is used to improve the electrical performance of the anode, and can be applied to materials commonly used in the art, but specifically, can include at least one selected from the group consisting of natural graphite, artificial graphite, carbon black, acetylene black, Denka black, Ketjen black, Super-P, channel black, furnace black, lamp black, summer black, graphene, and carbon nanotubes.

[0182] In addition, the conductive material may be included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of each positive electrode active layer, and specifically, may be included in an amount of 0.1 to 4 parts by weight; 2 to 4 parts by weight; 1.5 to 5 parts by weight; 1 to 3 parts by weight; 0.1 to 2 parts by weight; or 0.1 to 1 part by weight.

[0183] In addition, the binder serves to bind the positive electrode active material, the positive electrode additive, and the conductive material to each other, and any binder having this function may be used without particular limitation. Specifically, the binder may include at least one resin selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-co-HFP), polyvinylidene fluoride (PVdF), polyacrylonitrile, polymethylmethacrylate, and copolymers thereof. As an example, the binder may include polyvinylidene fluoride.

[0184] In addition, the binder may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the positive electrode active layer, specifically 2 to 8 parts by weight; or 1 to 5 parts by weight.

[0185] The total thickness of the above-mentioned positive electrode active layer is not particularly limited, but may be specifically in the range of 50 µm to 300 µm, and more specifically in the range of 100 µm to 200 µm; 80 µm to 150 µm; 120 µm to 170 µm; 150 µm to 300 µm; 200 µm to 300 µm; or 150 µm to 190 µm.

[0186] In addition, the positive electrode can be used as a positive electrode current collector that has high conductivity without causing chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, etc. can be used, and in the case of aluminum or stainless steel, a material surface-treated with carbon, nickel, titanium, silver, etc. can also be used. In addition, the average thickness of the current collector can be appropriately applied in the range of 3 to 500 ㎛, taking into account the conductivity and total thickness of the positive electrode to be manufactured.

[0187] In addition, the separator interposed between the positive and negative electrodes of each unit cell is an insulating thin film having high ion permeability and mechanical strength, and is not particularly limited as long as it is commonly used in the art, but specifically, one including at least one polymer selected from the group consisting of polypropylene, polyethylene, and polyethylene-propylene copolymers having chemical resistance and hydrophobicity can be used. The separator may have a porous polymer substrate form such as a sheet or non-woven fabric including the above-described polymer, and in some cases, may have a composite separator form in which organic or inorganic particles are coated on the porous polymer substrate using an organic binder. In addition, the separator may have an average pore diameter of 0.01 to 10 μm, and an average thickness of 5 to 300 μm.

[0188] Meanwhile, the lithium secondary battery according to the present invention is not particularly limited, but may be a secondary battery having a stacked, zigzag, or zigzag-stacked electrode assembly. As an example, the lithium secondary battery according to the present invention may be a pouch-type secondary battery or a square-shaped secondary battery.

[0189] Pouch-type secondary batteries and / or square secondary batteries have the advantage of high utilization in terms of energy density because the unit cells of the secondary batteries can be packed at a high density in a limited space.

[0190] Furthermore, in the lithium secondary battery, the electrolyte composition can be used without particular limitation as long as it is one that is commonly applied to lithium secondary batteries.

[0191] Specifically, the electrolyte composition may include a non-aqueous organic solvent, a lithium salt, and an electrolyte additive.

[0192] Here, the non-aqueous organic solvent can be applied without particular limitation as long as it is used in a non-aqueous electrolyte in the art. For example, the non-aqueous organic solvents include N-methyl-2-pyrrolidinone, ethylene carbonate (EC), propylene carbonate (PC), propylene carbonate, butylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), gamma-butyrolactone, 1,2-dimethoxyethane (DME), tetrahydrofuran, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolan, formamide, dimethylformamide, dioxolan, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphoric acid, trimethoxy methane, dioxolan derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl pyropionate (MP), Non-protic organic solvents such as ethyl propionate (EP) and propyl propionate (PP) can be used.

[0193] In addition, the non-aqueous organic solvent used in the present invention may be used alone, or two or more types may be mixed in any combination or ratio according to the intended use. Among these, from the viewpoint of electrochemical stability against oxidation and reduction and chemical stability with respect to heat or reactions with solutes, it is particularly preferable to mix propylene carbonate, ethylene carbonate, fluoroethylene carbonate, diethyl carbonate, dimethyl carbonate, and ethylmethyl carbonate.

[0194] In addition, the lithium salt may be applied without particular limitation as long as it is used in a non-aqueous electrolyte in the art. Specifically, the lithium salt may be LiCl, LiBr, LiI, LiClO4, LiBF4, LiB 10 Cl 10 , LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, (CF3SO2)2NLi, and (FSO2)2NLi.

[0195] The lower limit of the appropriate concentration range for properly using the above lithium salt is 0.5 mol / L or more, specifically 0.7 mol / L or more, more specifically 0.9 mol / L or more, and the upper limit is 2.5 mol / L or less, specifically 2.0 mol / L or less, more specifically 1.5 mol / L or less. If the concentration of the lithium salt is less than 0.5 mol / L, there is a concern that the ionic conductivity may decrease, thereby deteriorating the cycle characteristics and output characteristics of the non-aqueous electrolyte battery. In addition, if the concentration of the lithium salt exceeds 2.5 mol / L, the viscosity of the electrolyte for the non-aqueous electrolyte battery increases, which may also deteriorate the ionic conductivity, and there is a concern that the cycle characteristics and output characteristics of the non-aqueous electrolyte battery may also deteriorate.

[0196] In addition, when a large amount of lithium salt is dissolved in a non-aqueous organic solvent at once, the temperature of the electrolyte may rise due to the heat of dissolution of the lithium salt. If the temperature of the non-aqueous organic solvent rises significantly due to the heat of dissolution of the lithium salt in this way, in the case of a lithium salt containing fluorine, there is a concern that decomposition may be accelerated and hydrogen fluoride (HF) may be generated. Hydrogen fluoride (HF) is not desirable because it causes deterioration of battery performance. Therefore, the temperature when dissolving the lithium salt in the non-aqueous organic solvent is not particularly limited, but can be controlled to -20 to 80°C, and specifically, can be controlled to 0 to 60°C.

[0197] Furthermore, the electrolyte additive may be included as an additional auxiliary component to improve the properties of the electrolyte composition. An electrolyte additive commonly used in the non-aqueous electrolyte of the present invention may be added in any ratio. Specifically, compounds having an overcharge prevention effect, a negative electrode film formation effect, and a positive electrode protection effect, such as cyclohexylbenzene, biphenyl, t-butylbenzene, carbonate, vinylethylene carbonate, difluoroanisole, fluoroethylene carbonate, propane sultone, succinonitrile, and dimethylvinylene carbonate, may be mentioned. In addition, it is also possible to use an electrolyte for a non-aqueous electrolyte battery by solidifying it with a gelling agent or a crosslinking polymer, such as in the case of use in a non-aqueous electrolyte battery called a lithium polymer battery.

[0198]

[0199] The lithium secondary battery according to the present invention has the above-described configuration, and thus has the advantage of not only having a large charge / discharge capacity and excellent life characteristics, but also being capable of being charged in a short time even at a 1C-rate.

[0200]

[0201] Method for manufacturing cathode

[0202] In addition, in one embodiment of the present invention,

[0203] A step of applying a negative electrode slurry to at least one surface of a negative electrode collector;

[0204] A step of applying a magnetic field to the applied cathode slurry; and

[0205] A method for manufacturing a cathode is provided, including a step of drying a cathode slurry to which a magnetic field is applied to form a cathode active layer.

[0206]

[0207] The method for manufacturing a negative electrode according to the present invention refers to the method for manufacturing the negative electrode of the present invention described above. The method for manufacturing the negative electrode comprises: applying a negative electrode slurry on a negative electrode current collector, applying a magnetic field to the surface of the applied negative electrode slurry, and then drying each negative electrode slurry, thereby manufacturing a negative electrode having a negative electrode active layer in which the crystal characteristics of the negative electrode active material are controlled.

[0208] Here, the step of applying the negative electrode slurry is a step of discharging and coating the negative electrode slurry containing a carbon-based negative electrode active material onto the surface of the moving negative electrode current collector. This step can be applied without particular limitation as long as it is a method commonly applied in the art, but preferably, a die coating method can be used. The die coating method can be performed through a slot die having a shim for controlling the discharging conditions of the negative electrode slurry. In this case, by controlling the shape, position, etc. of the shim, the loading amount, coating thickness, etc. of the negative electrode slurry applied onto the negative electrode current collector can be easily controlled.

[0209] Meanwhile, the step of applying a magnetic field to the negative electrode slurry may be a step of controlling the crystal characteristics of the negative electrode active material contained in the negative electrode slurry. Specifically, this step can align the ab-axis crystal planes of each carbon-based negative electrode active material contained in the negative electrode slurry to have a high angle with respect to the negative electrode collector by applying a magnetic field to the surface of the negative electrode slurry coated on the negative electrode current collector.

[0210] At this time, a magnetic field can be applied by magnets placed on the upper and lower portions of the negative electrode current collector, which is moved while the negative electrode slurry is applied to the surface. The polarities of the magnets placed on the upper and lower portions may be different from each other.

[0211] In addition, the alignment degree (OI) of the carbon-based negative electrode active material contained in each negative electrode slurry can be controlled by the strength of the applied magnetic field, the application time, etc., and accordingly, the step of applying the magnetic field can be performed under predetermined magnetic field strength conditions.

[0212] Specifically, the step of applying the magnetic field may apply a magnetic field in a range of 10,000 G (Gauss) or less, and specifically, the magnetic field may be applied with a strength in a range of 1,000 G to 7,000 G; 2,000 G to 6,000 G; 1,500 G to 5,000 G; 1,500 G to 4,500 G; 4,000 G to 7,000 G; 2,000 G to 4,000 G; 2,500 G to 3,500 G; 3,000 G to 6,500 G; or 2,700 G to 3,300 G.

[0213] Additionally, the step of applying the magnetic field may be performed for 1 second to 20 seconds, specifically, for 1 second to 15 seconds; 1 second to 10 seconds; 5 seconds to 20 seconds; 10 seconds to 20 seconds; 11 seconds to 18 seconds; 1 second to 5 seconds; 7 seconds to 13 seconds; or 6 seconds to 11 seconds.

[0214] As an example, in the step of applying the magnetic field, a magnetic field of 3,000±50 G may be applied to the cathode slurry for 9 to 11 seconds.

[0215] Furthermore, the step of applying the magnetic field is performed by magnets introduced to the upper and lower portions of the applied negative electrode slurry as mentioned above, and the size of the magnets may be adjusted to be larger than the size of the negative electrode slurry so that the magnetic field applied to the negative electrode slurry can be uniformly applied to the entire surface of the negative electrode slurry. For example, the magnets may have a length ratio in the range of 105% to 200% based on the width direction length of the negative electrode slurry, and specifically, may have a length ratio in the range of 110% to 180%; 110% to 160%; 110% to 140%; 110% to 130%; 130% to 150%; or 105% to 120% based on the width direction length of the negative electrode slurry.

[0216] The present invention can uniformly implement the alignment degree (OI) of a carbon-based negative electrode active material contained in a negative electrode slurry so as to satisfy a predetermined range by controlling the strength of the magnetic field, the application time, and / or the size of the magnet portion as described above in the step of applying the magnetic field.

[0217] Additionally, the step of forming the cathode active layer may include a step of drying the cathode slurry; and a step of rolling the dried cathode slurry.

[0218] At this time, the step of drying the negative electrode slurry can be applied without any particular limitation as long as it is a method capable of maintaining the orientation of the carbon-based negative electrode active material contained in the negative electrode active layer.

[0219] For example, the drying step can dry the cathode slurry by applying heat energy to the cathode slurry using a hot air dryer, a vacuum oven, or the like.

[0220] In addition, the step of rolling the dried cathode slurry is a step of increasing the density of the cathode active layer by applying pressure to the dried cathode slurry using a roll press or the like.

[0221] The above rolling can be performed at a temperature of 20°C to 100°C, more specifically, 20°C to 80°C; 20°C to 60°C; 20°C to 40°C; 20°C to 30°C; 60°C to 100°C; 75°C to 100°C; 85°C to 100°C; 50°C to 90°C; 60°C to 80°C; or 65°C to 90°C.

[0222] In addition, the rolling can be performed at a rolling speed of 2 m / s to 7 m / s, and more specifically, 2 m / s to 6.5 m / s; 2 m / s to 6 m / s; 2 m / s to 5.5 m / s; 2 m / s to 5 m / s; 2 m / s to 4.5 m / s; 2 m / s to 4 m / s; 2.5 m / s to 4 m / s; 2.5 m / s to 3.5 m / s; 3.5 m / s to 5 m / s; 5 m / s to 7 m / s; 5.5 m / s to 6.5 m / s or 6 m / s to 7 m / s.

[0223] In addition, the rolling can be performed under a pressure condition of 50 MPa to 200 MPa, and specifically, it can be performed under a pressure condition of 50 MPa to 150 MPa; 50 MPa to 100 MPa; 100 MPa to 200 MPa; 150 MPa to 200 MPa or 80 MPa to 140 MPa.

[0224] The present invention can increase the energy density of a negative electrode while minimizing changes in the alignment of a carbon-based negative electrode active material contained in a negative electrode active layer formed by performing rolling of a dried negative electrode slurry under the above-described temperature, speed, and / or pressure conditions.

[0225]

[0226] Hereinafter, the present invention will be described in more detail through examples and experimental examples.

[0227] However, the following examples and experimental examples are only illustrative of the present invention, and the content of the present invention is not limited to the following examples and experimental examples.

[0228]

[0229] Examples 1 to 7 and Comparative Examples 1 to 3. Preparation of negative electrode for lithium secondary battery

[0230] As a carbon-based negative electrode material, the primary particles are assembled into artificial graphite (average particle diameter (D)) of secondary particles. 50 ): 16±0.1㎛) and silicon dioxide (SiO2, average particle diameter (D) as a silicon-based negative electrode active material 50 ): 8.0±0.1㎛) was prepared. In addition, styrene butadiene rubber (SBR) was prepared as a binder and carboxymethyl cellulose (CMC) was prepared as a thickener.

[0231] Then, 96 parts by weight of first artificial graphite and silicon dioxide (SiO2), 1.5 parts by weight of carboxymethyl cellulose (CMC), and 2.5 parts by weight of styrene butadiene rubber (SBR) were mixed with water to obtain a solid content of 50% to prepare a first negative electrode slurry. At this time, the content ratio of the first artificial graphite and silicon dioxide (SiO2) of the first negative electrode slurry that constitute the first negative electrode active layer was controlled as shown in Table 1 below for the total negative electrode active material contained in the first negative electrode slurry.

[0232] Additionally, 96 parts by weight of second artificial graphite, 1.5 parts by weight of carboxymethyl cellulose (CMC), and 2.5 parts by weight of styrene butadiene rubber (SBR) were mixed with water to obtain a solid content of 50% to prepare a second negative electrode slurry.

[0233] Once each cathode slurry was prepared, the first cathode slurry and the second cathode slurry were simultaneously cast on a copper foil (thickness: 10 μm) being transported roll-to-roll (transport speed: 5 m / min) using a dual die coater. At this time, the cast first cathode slurry and second cathode slurry were adjusted to have the same loading amount and thickness, and the total loading amounts of the first cathode slurry and the second cathode slurry are shown in Table 1 below.

[0234] A permanent magnet having a length ratio of 110 to 120% of the widthwise length of the negative electrode slurry was placed on the upper side of the applied negative electrode slurry and on the lower side of the negative electrode current collector, and a magnetic field was applied with a magnetic field strength of 3,000±20 G. At this time, the time for which the magnetic field was applied is shown in Table 1. The negative electrode slurry to which the magnetic field was applied was dried with hot air, and the negative electrode was formed in the form of a first negative electrode active layer and a second negative electrode active layer sequentially stacked on the negative electrode current collector. The formed negative electrode active layer was rolled at 50±1°C, a pressure of 100 to 150 MPa, and a conveying speed of 3 m / s, to manufacture a negative electrode for a lithium secondary battery.

[0235] For each manufactured cathode, X-ray diffraction (XRD) was performed on the first cathode active layer and the second cathode active layer to measure the spectrum. At this time, in the case of the first cathode active layer, after measuring the X-ray diffraction (XRD) of the second cathode active layer, the second cathode active layer was peeled off and removed, and then X-ray diffraction was measured on the exposed surface of the first cathode active layer. In addition, the measurement conditions for X-ray diffraction (XRD) were as follows:

[0236] - Target: Cu(Kα line) graphite monochromator

[0237] - Slit: Diverging slit = 1 degree, Receiving slit = 0.1 mm, Scatter slit = 1 degree

[0238] - Measurement area: (110) plane: 76.5° < 2θ < 78.5° / (004) plane: 53.5° < 2θ < 56.0°.

[0239]

[0240] The average alignment index (OI) of the carbon-based active material contained in each cathode active layer was calculated from the spectra measured under the above conditions using Equation 1. The results are shown in Table 1:

[0241] [Formula 1]

[0242] OI = I 004 / I 110

[0243] In equation 1,

[0244] I 004 represents the area of ​​the peak representing the (004) crystal plane of the carbon-based negative electrode material in the X-ray diffraction (XRD) spectroscopy analysis of the negative electrode active layer,

[0245] I 110 represents the area of ​​the peak representing the (110) crystal plane of the carbon-based negative electrode material in X-ray diffraction (XRD) spectroscopy analysis of the negative electrode active layer.

[0246] Content ratio [wt%] Total loading amount of cathode slurry Alignment (OI) OI 1st / OI 2cn Magnetic field applied first artificial graphite SiOO.I 1st OI 2cn Whether Time Example 1991 15~20 mg / cm2 881.009~11 seconds Example 2955 15~20 mg / cm2 780.87509~11 seconds Example 3901015~20 mg / cm2 981.12509~11 seconds Example 4851 515~20 mg / cm2 680.75009~11 seconds Example 5802 15~20 mg / cm2 780.87509~11 seconds Example 6955 5~7 mg / cm2 5.58 0.68809~11 seconds Example 7955 25~30 mg / cm2 9.58 1.1909~11 seconds Comparative Example 1955 15~20 mg / ㎠23201.15X0 secondsComparative example 295515~20 mg / ㎠1381.625O1~2 secondsComparative example 3100015~20 mg / ㎠881.0O9~11 seconds

[0247]

[0248]

[0249] Comparative Example 4. Manufacturing of a negative electrode for a lithium secondary battery

[0250] A first negative electrode slurry and a second negative electrode slurry were prepared in the same manner as in Example 1. Thereafter, the first negative electrode slurry was cast on a copper foil (thickness: 10 μm) using a single die coater. A permanent magnet having a length ratio of 110 to 120% of the widthwise length of the negative electrode slurry was placed on the upper portion of the applied first negative electrode slurry and the lower portion of the negative electrode current collector, and a magnetic field of 8,500 ± 100 G was applied to the surface of the first negative electrode slurry for 15 seconds, and then the second negative electrode slurry was cast on the first negative electrode slurry to which the magnetic field was applied. At this time, the loading amount and thickness of the cast first negative electrode slurry and the second negative electrode slurry were controlled to be the same. A magnetic field of 3,000 ± 20 G was applied to the applied second negative electrode slurry using the permanent magnet used previously. A negative electrode slurry to which a magnetic field was applied was dried with hot air to form a negative electrode in which a first negative electrode active layer and a second negative electrode active layer were sequentially laminated on a negative electrode current collector. The formed negative electrode active layer was rolled at 50±1°C under a pressure of 100 to 150 MPa and a conveying speed of 3 m / s to manufacture a negative electrode for a lithium secondary battery (average thickness of each negative electrode active layer: 50±5 μm, loading amount: 15 to 20 mg / cm2).

[0251] For the cathode manufactured in the same manner as Example 1, X-ray diffraction (XRD) was performed on the first cathode active layer and the second cathode active layer to measure the spectrum. From the measured spectrum, the average degree of alignment (OI) of each cathode active layer was calculated using Equation 1. The degree of alignment (OI) of the first cathode active layer and the second cathode active layer was 4 and 8, respectively, and their ratio (OI 1st / OI 2cn ) was 0.5.

[0252]

[0253] Comparative Example 5. Manufacturing of a negative electrode for a lithium secondary battery.

[0254] In Example 1, the positions of the first negative electrode slurry and the second negative electrode slurry were swapped during casting of the negative electrode slurry, except that the silicon-based negative electrode active material was included in the first negative electrode active layer, thereby manufacturing a negative electrode for a lithium secondary battery using the same method as in Example 1. At this time, the loading amounts of the cast first negative electrode slurry and the second negative electrode slurry were adjusted to be the same, and the total loading amounts of the first negative electrode slurry and the second negative electrode slurry were 15 to 20 mg / cm2. In addition, the manufactured negative electrode has a structure in which the positions of the first negative electrode active layer and the second negative electrode active layer are swapped in the negative electrode manufactured in Example 1.

[0255] For the cathode manufactured in the same manner as Example 1, X-ray diffraction (XRD) was performed on the first cathode active layer and the second cathode active layer to measure the spectrum. From the measured spectrum, the average degree of alignment (OI) of each cathode active layer was calculated using Equation 1. The degree of alignment (OI) of the first cathode active layer and the second cathode active layer was 8 and 22, respectively, and their ratio (OI 1st / OI 2cn ) was 0.37.

[0256]

[0257] Examples 8 to 14 and Comparative Examples 6 to 10. Manufacturing of lithium secondary batteries

[0258] LiNi with a particle size of 5㎛ as a cathode active material 0.7 Co 0.1 Mn 0.1 Al 0.1 O2 was prepared, and polyvinylidene fluoride as a carbon-based conductive agent and binder and N-methyl pyrrolidone (NMP) were mixed in a weight ratio of 94:3:3 to form a slurry, which was cast on an aluminum sheet, dried in a vacuum oven at 120°C, and then rolled to manufacture a cathode.

[0259] A separator made of 18 μm polypropylene was interposed between the positive electrode obtained above and the negative electrode manufactured in Examples 1 to 7 and Comparative Examples 1 to 5, respectively, and inserted into a case, and then an electrolyte composition was injected to assemble a 1 Ah-class lithium secondary battery.

[0260] At this time, the types of negative electrodes applied to each lithium secondary battery are shown in Table 2 below.

[0261] Type of applied cathode Example 8 The cathode manufactured in Example 1 Example 9 The cathode manufactured in Example 2 Example 10 The cathode manufactured in Example 3 Example 11 The cathode manufactured in Example 4 Example 12 The cathode manufactured in Example 5 Example 13 The cathode manufactured in Example 6 Example 14 The cathode manufactured in Example 7 Comparative Example 6 The cathode manufactured in Comparative Example 1 Comparative Example 7 The cathode manufactured in Comparative Example 2 Comparative Example 8 The cathode manufactured in Comparative Example 3 Comparative Example 9 The cathode manufactured in Comparative Example 4 Comparative Example 10 The cathode manufactured in Comparative Example 5

[0262]

[0263]

[0264] Experimental example.

[0265] In order to evaluate the performance of the negative electrode according to the present invention, the following experiments were conducted on each negative electrode and lithium secondary battery manufactured in the examples and comparative examples.

[0266]

[0267] 1) Evaluation of adhesion to the negative electrode collector

[0268] The negative electrodes manufactured in Examples 1 to 7 and Comparative Examples 1 to 5 were cut to have lengths of 25 mm and 70 mm, respectively, to prepare specimens. The prepared specimens were attached to a glass plate using double-sided tape, and the current collector was positioned so that it faced the glass plate. After the specimens fixed to the glass plate were fixed to a tensile tester, the negative active layer of each negative electrode was pulled at a speed of 100 mm / min at 25°C so as to form a 90° angle with the negative current collector and detached. The peeling force measured in real time was defined as the interfacial adhesive strength between the negative current collector and the negative active layer, and the measured results are shown in Table 3 below.

[0269]

[0270] 2) Life characteristics evaluation

[0271] Each of the lithium secondary batteries manufactured in Examples 8 to 14 and Comparative Examples 6 to 10 was charged to 4.2 V under CC-CV conditions at a rate of 0.3 C at 25°C, and then discharged to 2.5 V under CC conditions at a rate of 0.3 C to activate them.

[0272] Each activated lithium secondary battery was charged at a temperature of 25℃ at a rate of 1.0C to 4.2V under CC-CV conditions, and discharged at a rate of 1.0C to 2.5V under CC conditions, which was set as one cycle, and one cycle of charge-discharge was performed on each lithium secondary battery manufactured in the examples and comparative examples. At this time, the capacity during charge-discharge was measured to confirm the charge-discharge capacity of the first cycle. After that, 499 cycles of charge-discharge were performed on each lithium secondary battery, and a total of 500 cycles of charge-discharge were performed. At this time, the charge-discharge capacity of the 500th cycle was confirmed when the last cycle was performed. The charge-discharge capacity retention rate of the 500th cycle was calculated based on the measured charge-discharge capacity of the 1st cycle. The results are shown in Table 3 below.

[0273]

[0274] 3) 1C-rate rapid charging evaluation

[0275] Each of the lithium secondary batteries manufactured in Examples 8 to 14 and Comparative Examples 6 to 10 was charged to 4.2 V under CC-CV conditions at a rate of 0.3 C at 25°C, and then discharged to 2.5 V under CC conditions at a rate of 0.3 C to activate them.

[0276] Each activated lithium secondary battery was charged at 25°C using the constant current-constant voltage (CC-CV) method, and the time required for the state of charge (SOC) to reach 80% was measured. At this time, the charging was performed using constant current (CC) charging at a current of 1.0 C-rate until the voltage reached 4.2 V, followed by constant voltage (CV) charging, which maintained 4.2 V and cut-off when the current reached 0.005 C-rate. The measured charging times are shown in Table 3 below.

[0277] Type of negative electrode Adhesion [gf / cm] Capacity retention [%] Charging time (SOC 80%) Example 8 Negative electrode manufactured in Example 1 319327 seconds Example 9 Negative electrode manufactured in Example 2 349219 seconds Example 10 Negative electrode manufactured in Example 3 38017 seconds Example 11 Negative electrode manufactured in Example 4 294016 seconds Example 12 Negative electrode manufactured in Example 5 282012 seconds Example 13 Negative electrode manufactured in Example 6 219216 seconds Example 14 Negative electrode manufactured in Example 7 298826 seconds Comparative Example 6 Negative electrode manufactured in Comparative Example 1 259048 seconds Comparative Example 7 Negative electrode manufactured in Comparative Example 2 278939 seconds Comparative Example 8 Comparative Example Cathode manufactured in 3 259530 seconds Comparative example 9 Cathode manufactured in Comparative example 4 177124 seconds Comparative example 10 Cathode manufactured in Comparative example 5 86017 seconds

[0278]

[0279]

[0280] As shown in Table 3 above, the negative electrode for a lithium secondary battery according to the present invention has excellent adhesion between the negative electrode active layer and the negative electrode current collector, excellent life characteristics, and can be quickly charged under 1C-rate conditions.

[0281] Specifically, the negative electrodes manufactured in the examples exhibited an adhesive strength between the negative electrode current collector and the negative electrode active layer of 28 gf / cm or more. In particular, when the content of silicon dioxide contained in the first negative electrode active layer and the total loading of the negative electrode active layer satisfied the range of the present invention, a high adhesive strength of 30 gf / cm or more was exhibited.

[0282] In addition, the secondary batteries of the examples were shown to reach a state of charge (SOC) of 80% in less than 30 seconds under standard constant current-constant voltage (CC-CV) charging conditions of 1C-rate. In addition, the secondary batteries of the examples showed high charge-discharge capacity retention after 500 charge-discharge cycles. In particular, when the first negative electrode active layer contained less than 15 wt% of silicon dioxide, a high capacity retention of 80% or more was shown.

[0283] On the other hand, the negative electrodes manufactured in the comparative example showed low adhesion between the negative electrode current collector and the negative electrode active layer, less than 28 gf / cm.

[0284] In addition, in terms of life characteristics, the negative electrode of Comparative Example 3, which does not include silicon dioxide (SiO2), a silicon-based negative electrode active material, as a negative electrode active material, showed a relatively high charge / discharge capacity retention rate of about 95% after 500 cycles of charge / discharge of the secondary battery, but it was confirmed that the charge / discharge capacity of one cycle was significantly lower compared to the negative electrodes of the examples including silicon dioxide (SiO2).

[0285] In addition, when manufacturing the cathode, the alignment degree (OI) of the first cathode active layer is not applied to the cathode slurry or is applied to the cathode slurry. 1st ) exceeded 0.5 to 1.5, the cathodes of Comparative Examples 1, 2 and 4 reached 80% state of charge (SOC) after a long time of more than 30 seconds under the 1C-rate standard constant current-constant voltage (CC-CV) charging conditions of secondary batteries.

[0286] This means that the life characteristics of the negative electrode and the charging speed under standard C-rate conditions can be improved by controlling the alignment degree (OI) of the first carbon-based negative electrode active material included in the first negative electrode active layer and the content of the silicon-based negative electrode active material.

[0287]

[0288] From these results, it can be seen that the negative electrode for a lithium secondary battery according to the present invention has excellent adhesion between the negative electrode active layer and the negative electrode current collector, has a large charge / discharge capacity, and has excellent life characteristics, and a lithium secondary battery including the same can be charged in a short time even at a 1C-rate.

[0289]

[0290] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art or having ordinary knowledge in the art that the present invention can be variously modified and changed within a scope that does not depart from the technical scope of the present invention as set forth in the claims to be described below.

[0291] Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the patent claims.

Claims

1. Negative current collector, A first negative electrode active layer provided on at least one surface of the negative electrode current collector and containing a first carbon-based negative electrode active material and a silicon-based negative electrode active material, and A second cathode active layer is provided on the first cathode active layer and contains a second carbon-based cathode active material; The above first cathode active layer is, The alignment (OI) is expressed by the following equation 1 1st ) is in the range of 5 to 15, A negative electrode for a lithium secondary battery satisfying the following equation 2 with a value greater than 0.6 and less than or equal to 1.5: [Formula 1] OI = I 004 / I 110 [Formula 2] OI 1st / OI 2nd In equations 1 and 2, I 004 represents the area of ​​the peak representing the (004) crystal plane of the carbon-based negative electrode material in X-ray diffraction (XRD) spectroscopy analysis of the negative electrode active layer, I 110 represents the area of ​​the peak representing the (110) crystal plane of the carbon-based negative electrode material in X-ray diffraction (XRD)0 spectroscopy analysis of the negative electrode active layer. OI 1st represents the alignment degree of the first carbon-based negative electrode active material contained in the first negative electrode active layer, OI 2nd It shows the alignment degree of the second carbon-based negative electrode active material contained in the second negative electrode active layer.

2. In paragraph 1, A negative electrode for a lithium secondary battery, wherein the silicon-based negative electrode active material is included in an amount of more than 0 wt% and less than 15 wt% based on the weight of the first negative electrode active layer.

3. In paragraph 1, A negative electrode for a lithium secondary battery, wherein the first negative active layer has an alignment index (OI) in the range of 7 to 12.

4. In paragraph 1, The average particle diameter (D) of the first carbon-based negative electrode active material and the second carbon-based negative electrode active material 50 ) are in the range of 1㎛ to 30㎛, respectively. The average particle diameter (D) of the above silicon-based negative electrode active material 50 ) is a negative electrode for a lithium secondary battery having a range of 0.5㎛ to 20㎛.

5. In paragraph 1, A negative electrode for a lithium secondary battery, wherein the first carbon-based negative electrode active material and the second carbon-based negative electrode active material each include at least one of natural graphite and artificial graphite.

6. In paragraph 1, The above silicon-based negative electrode active materials include silicon (Si), silicon carbide (SiC), and silicon oxide (SiO). q , but, 0.8≤q≤2.5) containing at least one of the negative electrodes for a lithium secondary battery.

7. In paragraph 1, A negative electrode for a lithium secondary battery, wherein the total loading of the first negative electrode active layer and the second negative electrode active layer is in the range of 0.5 to 20 mg / cm2.

8. A step of applying a cathode slurry to at least one surface of a cathode current collector; A step of applying a magnetic field to the applied cathode slurry; and A method for manufacturing a negative electrode for a lithium secondary battery according to claim 1, comprising a step of drying a negative electrode slurry to which a magnetic field is applied to form a negative electrode active layer.

9. In paragraph 8, A method for manufacturing a negative electrode for a lithium secondary battery, wherein the step of applying the magnetic field is performed for 1 to 20 seconds.

10. In paragraph 8, A method for manufacturing a negative electrode for a lithium secondary battery, wherein the step of applying the magnetic field is performed with a magnetic field strength ranging from 1,000 G to 7,000 G.

11. An electrode assembly comprising a positive electrode, a negative electrode according to claim 1, and a separator disposed between the positive electrode and the negative electrode; and A lithium secondary battery comprising an electrolyte composition in which the electrode assembly is impregnated.

12. In paragraph 11, The above positive electrode is provided on at least one side of the positive electrode current collector and includes a positive electrode active layer including at least one type of positive electrode active material among lithium metal oxides represented by the following chemical formulas 1 and 2: A lithium secondary battery: [Chemical Formula 1] Li x [Ni y Co z Mr w M 1 v ]O 2 [Chemical formula 2] Glue 2 p Mn 1-p O 4 In the above chemical formulas 1 and 2, M 1 is at least one element among W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, x, y, z, w and v are 1.0≤x≤1.30, 0.5≤y<1, 0 respectively. <z≤0.3, 0<w≤0.3, 0≤v≤0.1이되, y+z+w+v=1이고, M 2 is Ni, Co or Fe, p is 0.05≤p≤1.

0.

13. In paragraph 11, The above cathode active material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 , LiNi 0.6 Co 0.2 Mn 0.2 O 2 , LiNi 0.9 Co 0.05 Mn 0.05 O 2 , LiNi 0.6 Co 0.2 Mn 0.1 Al 0.1 O 2 , LiNi 0.6 Co 0.2 Mn 0.15 Al 0.05 O 2 , LiNi 0.7 Co 0.1 Mn 0.1 Al 0.1 O 2 , LiNi 0.7 Mn 1.3 O 4 , LiNi 0.5 Mn 1.5 O 4 and LiNi 0.3 Mn 1.7 O 4 A lithium secondary battery comprising at least one of the following:

14. In paragraph 11, A lithium secondary battery wherein the electrode assembly is a stacked electrode assembly; a zigzag electrode assembly; or a zigzag-stacked electrode assembly.