Positive electrode and rechargeable lithium battery

Abstract

Disclosed are a positive electrode and a rechargeable lithium battery including the same. The positive electrode may include a positive electrode current collector, a first positive electrode active material layer disposed on the positive electrode current collector and including a first positive electrode active material, and a second positive electrode active material layer disposed on the first positive electrode active material layer and including a second positive electrode active material, the first positive electrode active material may include a lithium iron phosphate-based compound, the second positive electrode active material may include a lithium cobalt-based oxide, and a weight ratio of the second positive electrode active material to the first positive electrode active material may be about 40 to about 55.

Description

Technical Field

[0001] One or more embodiments of this disclosure relate to a positive electrode and a rechargeable lithium battery. Background Technology

[0002] Portable information devices (such as cellular phones, laptops, smartphones, etc.) and / or electric vehicles use rechargeable lithium batteries with relatively high energy density and easy portability as driving power sources. Recently, research has been conducted on using rechargeable lithium batteries with high energy density as driving power sources in hybrid and / or electric vehicles and / or as energy storage power sources in energy storage systems and / or power walls.

[0003] Various positive electrode active materials have been studied to develop (realize or provide) rechargeable lithium batteries for these applications. Among them, lithium nickel oxides, lithium nickel manganese cobalt composite oxides, lithium nickel cobalt aluminum composite oxides, and lithium cobalt oxides are mainly or predominantly used as positive electrode active materials. With the increasing demand for large, high-capacity and / or high-energy-density rechargeable lithium batteries, the development of new and / or improved positive electrode active materials is expected. Summary of the Invention

[0004] One or more aspects of embodiments of this disclosure relate to a positive electrode having excellent or suitable safety and / or improved or enhanced capacity (e.g., electrical capacity) characteristics and a rechargeable lithium battery including the positive electrode.

[0005] Other aspects will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the disclosed embodiments.

[0006] In some example embodiments, the positive electrode includes: a positive electrode current collector; a first positive electrode active material layer disposed on the positive electrode current collector and including the first positive electrode active material; and a second positive electrode active material layer disposed on the first positive electrode active material layer and including the second positive electrode active material; wherein the first positive electrode active material includes a lithium iron phosphate compound, the second positive electrode active material includes a lithium cobalt oxide, and the weight ratio of the second positive electrode active material to the first positive electrode active material is about 40 to about 55.

[0007] In some exemplary embodiments, the rechargeable lithium battery includes: a positive electrode as described in one or more embodiments; a negative electrode; and an electrolyte.

[0008] According to one or more embodiments, the positive electrode can ensure or provide excellent or suitable safety while improving or enhancing capacity (e.g., electrical capacity) characteristics. Rechargeable lithium batteries including a positive electrode as described in one or more embodiments can exhibit high initial capacity characteristics and long cycle life characteristics even under high-voltage drive conditions, while improving or enhancing safety. Attached Figure Description

[0009] The accompanying drawings, together with the specification, illustrate embodiments of the subject matter of this disclosure and, together with the specification, serve to explain the principles of the embodiments of the subject matter of this disclosure.

[0010] Figures 1 to 4 All of these are schematic cross-sectional views of a rechargeable lithium battery according to one or more embodiments.

[0011] Figure 5 This is a schematic cross-sectional view of a positive electrode according to one or more embodiments. Detailed Implementation

[0012] Embodiments of this disclosure will be described in more detail below so that those skilled in the art can readily implement them. However, the subject matter of this disclosure may be embodied in one or more suitable forms and should not be construed as limited to the embodiments set forth herein.

[0013] The terminology used herein is for describing particular embodiments only and is not intended to limit this disclosure. Unless the context clearly indicates otherwise, singular expressions include plural expressions.

[0014] As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are also intended to include the plural forms. Furthermore, when describing embodiments of this disclosure, the use of “may” refers to “one or more embodiments of this disclosure.”

[0015] In the context of this disclosure and unless otherwise defined, the term “use” and its variations may be considered synonymous with the term “utilize” and its variations, respectively.

[0016] As used herein, the term “about” or similar terms are used as approximations rather than terms of degree and are intended to account for the inherent biases of measured or calculated values ​​that would be recognized by one of ordinary skill in the art. As used herein, “about” or “approximation” also includes the stated value and refers to an acceptable range of deviation for a particular value as determined by one of ordinary skill in the art, taking into account the measurement in question and errors associated with the measurement of the particular quantity (e.g., limitations of the measurement system). For example, “about” may mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0017] Any numerical range described herein is intended to include all subranges containing substantially the same numerical precision within the described range. For example, the range “1.0 to 10.0” is intended to include all subranges between the described minimum value 1.0 and the described maximum value 10.0 (and including both the described minimum value 1.0 and the described maximum value 10.0), i.e., having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as 2.4 to 7.6. Any maximum numerical limit described herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit described in this specification is intended to include all higher numerical limits contained therein. Therefore, the applicant reserves the right to modify this disclosure (including the appended claims) to expressly describe any subranges contained within the range expressly described herein.

[0018] As used herein, “combinations of” refers to mixtures, laminates, complexes, copolymers, alloys, blends, reaction products, etc. of the components.

[0019] Here it will be understood that terms such as “comprising,” “including,” or “having” are intended to specify the features, quantities, steps (e.g., actions or tasks), elements, and / or combinations thereof embodied in the presence, but do not preclude the possibility of the presence or addition of one or more other features, quantities, steps (e.g., actions or tasks), elements, and / or combinations thereof.

[0020] In the accompanying drawings, for clarity, the thickness of layers, films, panels, regions, etc., is exaggerated, and the same reference numerals denote the same elements throughout the specification. It will be understood that if (for example, when) an element such as a layer, film, region, or substrate is referred to as "on" another element, it may be directly on said other element, or an intermediary element may be present. Conversely, if (for example, when) an element is referred to as "directly on" another element, no intermediary element is present.

[0021] In one or more embodiments, the term "layer" here includes not only shapes that are formed or disposed on the entire surface when viewed from a plan view, but also shapes that are formed or disposed on a portion of the surface.

[0022] The average particle size can be measured using methods commonly used or available to those skilled in the art, for example, by a particle size analyzer and / or by transmission electron microscopy (TEM) images and / or scanning electron microscopy (SEM) images. In one or more embodiments, the average particle size value can be measured and obtained by using dynamic light scattering (DLS) methods to perform data analysis, count the number of particles in each particle size range, and calculate from this information. Unless otherwise defined, the average particle size can refer to the diameter (D) of particles having a cumulative volume of 50% of the particle size distribution. 50 As used herein, unless otherwise defined, mean particle size refers to the diameter of 50% by volume of particles in a particle size distribution obtained by randomly measuring the size (e.g., diameter or major axis length) of approximately 20 particles in a scanning electron microscope image. 50 D 50 "Diameter" can refer to the average diameter (or size) of the particles whose cumulative volume corresponds to 50% of the total volume in a particle size distribution (e.g., a cumulative distribution), and can also refer to the value corresponding to 50% of the particle size, starting from the smallest particle, in a cumulative distribution curve accumulated in order from the smallest to the largest particle size, when the total number of particles is 100%. In this disclosure, "diameter" indicates the average particle size if (e.g., when) the particles are spherical, and "diameter" indicates the length of the major axis if (e.g., when) the particles are non-spherical.

[0023] Here, "or" will not be interpreted as having an exclusive meaning; for example, "A or B" is interpreted as including A, B, or A+B.

[0024] The term "metal" is interpreted as encompassing common metals, transition metals, and metalloids (semi-metals).

[0025] positive electrode In one or more embodiments, the positive electrode may include: a positive electrode current collector; a first positive electrode active material layer disposed on the positive electrode current collector and including the first positive electrode active material; and a second positive electrode active material layer disposed on the first positive electrode active material layer and including the second positive electrode active material; wherein the first positive electrode active material may include a lithium iron phosphate compound, the second positive electrode active material may include a lithium cobalt oxide, and the weight ratio of the second positive electrode active material to the first positive electrode active material may be from about 40 to about 55.

[0026] To meet the demands for high capacity (e.g., electrical capacity), high energy density, and reduced cost in rechargeable lithium-ion batteries, positive electrode active materials with olivine crystal structures, such as lithium iron phosphate (LFP) and lithium manganese iron phosphate (LMFP), have been researched and are being pursued. However, positive electrode active materials with this olivine crystal structure have low lithium utilization, which limits their ability to achieve high capacity (e.g., electrical capacity).

[0027] Meanwhile, in one or more embodiments, lithium cobalt-based positive electrode active materials with layered crystal structures have high lithium capacity within the structure, and therefore have excellent or suitable capacity (e.g., electrical capacity) and efficiency (e.g., electrical efficiency) characteristics, making them suitable as materials for high-capacity batteries. However, they have relatively low safety issues in battery bending tests, etc.

[0028] Therefore, one or more embodiments of this disclosure provide a method for ensuring or providing the safety of a rechargeable lithium battery and achieving high capacity characteristics in parallel (e.g., simultaneously) by providing a bilayer composite positive electrode active material layer using lithium iron phosphate compounds and lithium cobalt oxides.

[0029] If (for example, when) a positive electrode active material layer is formed or provided by using lithium iron phosphate compounds alone, it is not easy to achieve a battery with high capacity (e.g., electrical capacity), even if the safety of a rechargeable lithium battery is ensured or provided. Therefore, in Figure 5 The cross-sectional view schematically illustrates the structure of a positive electrode capable of achieving high-capacity (e.g., charge) characteristics while ensuring the safety of a rechargeable lithium battery. According to one or more embodiments, the positive electrode 10 may include: a positive electrode current collector 300; a first positive electrode active material layer 301 disposed on the positive electrode current collector and including the first positive electrode active material 201; and a second positive electrode active material layer 302 disposed on the first positive electrode active material layer and including the second positive electrode active material 202. In one or more embodiments, the first positive electrode active material 201 may include a lithium iron phosphate compound, and the second positive electrode active material 202 may include a lithium cobalt oxide. In this way, by configuring the positive electrode active material layer as a double layer, such that a first positive electrode active material layer 301 including a lithium iron phosphate compound and a second positive electrode active material layer 302 including a lithium cobalt oxide can be formed or disposed on the positive electrode current collector 300, can ensure or provide excellent or suitable safety and high-capacity (e.g., charge) characteristics in parallel (e.g., simultaneously).

[0030] In other words, one or more embodiments of this disclosure provide a method for ensuring the safety of rechargeable lithium batteries while simultaneously (e.g., concurrently) achieving high capacity characteristics. This can be achieved by using lithium iron phosphate compounds and lithium cobalt oxides to provide a bilayer composite positive electrode active material layer.

[0031] Achieving high-capacity batteries is challenging even when the safety of rechargeable lithium batteries is ensured, for example, if only lithium iron phosphate compounds are used to form or provide the positive electrode active material layer. Therefore, a positive electrode structure capable of achieving high-capacity characteristics while ensuring safety is shown below. Figure 5 middle.

[0032] According to some embodiments, the positive electrode may include a positive electrode current collector, a first positive electrode active material layer comprising a lithium iron phosphate compound on the positive electrode current collector, and a second positive electrode active material layer comprising a lithium cobalt oxide on the first positive electrode active material layer. By forming or providing the positive electrode active material layer as a bilayer structure, excellent or suitable safety and high capacity characteristics can be ensured or provided in parallel (e.g., simultaneously).

[0033] In the positive electrode according to one or more embodiments, the weight ratio of the second positive electrode active material 202 to the first positive electrode active material 201 can be greater than or equal to about 40, for example, greater than or equal to about 45, greater than or equal to about 46, greater than or equal to about 48, or greater than or equal to about 50. In one or more embodiments, the weight ratio of the second positive electrode active material 202 to the first positive electrode active material 201 can be less than or equal to about 55, for example, less than or equal to about 54.5, less than or equal to about 54, or less than or equal to about 53.7. Throughout the positive electrode active material layer (e.g., the first positive electrode active material layer and the second positive electrode active material layer), the safety of the rechargeable lithium battery can be ensured or provided by including lithium iron phosphate compounds in the first positive electrode active material 201. Meanwhile, high capacity (e.g., charge capacity) characteristics that are difficult to ensure or provide when using lithium iron phosphate compounds as positive electrode active materials can be ensured or provided by combining them with lithium cobalt oxides in the second positive electrode active material 202. In one or more embodiments, by precisely or appropriately controlling the content (e.g., amount) ratio of the second positive electrode active material to the first positive electrode active material, it is possible to ensure or provide excellent or suitable capacity (e.g., capacity) characteristics while ensuring a desired or appropriate level of battery flexural safety.

[0034] The lithium iron phosphate compounds according to one or more embodiments may be compounds comprising lithium, phosphate and / or iron and may be represented by, for example, chemical formula 1.

[0035] Chemical Formula 1 Li a1 Fe x1 M 1 y1 M 2 z1 (PO 4-b1 )X b1 In chemical formula 1, 0.9 ≤ a1 ≤ 1.8, 0.1 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.7, 0 ≤ z1 ≤ 0.7, 0.9 ≤ x1 + y1 + z1 ≤ 1.1, and 0 ≤ b1 ≤ 0.1, M 1 and M 2 Each element may be independently selected from aluminum (Al), boron (B), barium (Ba), calcium (Ca), cerium (Ce), cobalt (Co), chromium (Cr), magnesium (Mg), manganese (Mn), molybdenum (Mo), niobium (Nb), silicon (Si), strontium (Sr), titanium (Ti), vanadium (V), tungsten (W), and zirconium (Zr), and X may be selected from fluorine (F), phosphorus (P), and sulfur (S).

[0036] For example, in chemical formula 1, the value of x1 can be selected from the following ranges: 0.1≤x1<1, 0.1≤x1≤0.9, 0.3≤x1≤1, 0.3≤x1<1, or 0.3≤x1≤0.9.

[0037] Lithium cobalt oxides according to one or more embodiments may be oxides comprising lithium and / or cobalt, and may be represented, for example, by chemical formula 2.

[0038] Chemical formula 2 Li a2 Co x2 M 3 y2 M 4 z2 O 2-b2 X b2 In chemical formula 2, 0.9 ≤ a² ≤ 1.8, 0.3 ≤ x² ≤ 1, 0 ≤ y² ≤ 0.7, 0 ≤ z² ≤ 0.7, 0.9 ≤ x² + y² + z² ≤ 1.1, and 0 ≤ b² ≤ 0.1, M 3 and M 4 Each element can be independently selected from one or more elements selected from Al, B, Ba, Ca, Ce, Cr, iron (Fe), Mg, Mn, Mo, Nb, Si, Sr, Ti, V, W, and Zr, and X can be selected from one or more elements selected from F, P, and S.

[0039] For example, based on 100 mol% of total metals excluding lithium, the cobalt content (e.g., amount) of lithium cobalt oxides can be greater than or equal to about 60 mol%, for example, greater than or equal to about 65 mol%, greater than or equal to about 70 mol%, greater than or equal to about 75 mol%, or greater than or equal to about 80 mol%. In one or more embodiments, based on 100 mol% of total metals excluding lithium, the cobalt content (e.g., amount) of lithium cobalt oxides can be less than or equal to about 100 mol%, for example, less than or equal to about 99 mol%, less than or equal to about 98 mol%, or less than or equal to about 95 mol%. If (e.g., when) the cobalt content (e.g., amount) of lithium cobalt oxides is within the above ranges, excellent or suitable structural safety can be ensured or provided, and it can also be more advantageous or beneficial to ensure battery (e.g., rechargeable lithium battery) capacity.

[0040] For example, LiFePO4 or LiFe can be used. x Mn (1-x) PO4 (0.1≤x≤0.9) and / or their (e.g., any suitable) combinations are used as lithium iron phosphate compounds, and LiCoO2 can be used as a lithium cobalt oxide.

[0041] In one or more embodiments, the average particle size of the first positive electrode active material may differ from the average particle size of the second positive electrode active material, for example, as... Figure 5 As shown, the average particle size of the first positive electrode active material 201 can be smaller than the average particle size of the second positive electrode active material 202. If this condition is met, the effect of ensuring excellent or suitable flexural safety and capacity (e.g., capacity) of the rechargeable lithium battery by using the first and second positive electrode active materials can be further improved or enhanced.

[0042] For example, the average particle size (D) of the first positive electrode active material 201 50 The average particle size (D) of the first positive electrode active material 201 can be greater than or equal to about 0.1 μm, for example, greater than or equal to about 0.3 μm, greater than or equal to about 0.5 μm, or greater than or equal to about 1 μm. In one or more embodiments, the average particle size (D) of the first positive electrode active material 201 is... 50 The surface area can be less than or equal to about 5 μm, for example, less than or equal to about 4.5 μm, less than or equal to about 4 μm, less than or equal to about 3 μm, less than or equal to about 2 μm, or less than or equal to about 1.3 μm. Within the foregoing range, it may be advantageous or beneficial to ensure or provide an excellent or suitable surface area to reduce energy loss and to ensure or provide excellent or suitable flexural safety and capacity (e.g., capacitance).

[0043] For example, the average particle size (D) of the second positive electrode active material 20250 The average particle size (D) of the second positive electrode active material 202 can be greater than or equal to about 8 μm, for example, greater than or equal to about 10 μm, greater than or equal to about 12 μm, greater than or equal to about 15 μm, or greater than or equal to about 17 μm. In one or more embodiments, the average particle size (D) of the second positive electrode active material 202 is... 50 The diameter (μm) can be less than or equal to about 30 μm, for example, less than or equal to about 28 μm, less than or equal to about 27 μm, less than or equal to about 26 μm, or less than or equal to about 25 μm. Within the foregoing range, high capacity (e.g., electrical capacity) characteristics of rechargeable lithium batteries can be effectively or appropriately ensured or provided.

[0044] For example, the average particle size of the second positive electrode active material can be about 4 times or more than the average particle size of the first positive electrode active material, such as about 5 times or more, about 8 times or more, about 10 times or more, about 15 times or more, about 20 times or more, or about 23 times or more. In one or more embodiments, the average particle size of the second positive electrode active material can be about 50 times or less than the average particle size of the first positive electrode active material, such as about 45 times or less, about 40 times or less, about 35 times or less, or about 30 times or less. Within the foregoing range, the effect of ensuring or providing excellent or suitable flexural stability and high capacity (e.g., capacitance) characteristics can be maximized or enhanced.

[0045] In one or more embodiments, the average particle size of the first positive electrode active material 201 and / or the second positive electrode active material 202 can be obtained by randomly measuring the size (e.g., diameter or major axis length) of about 20 particles using scanning electron microscopy images of each positive electrode active material to obtain a particle size distribution, and extracting the diameter (D) of particles that accumulate to 50% of the total volume from the particle size distribution. 50 The average particle size is obtained as the average particle size.

[0046] In one or more embodiments, based on a 100wt% first positive electrode active material layer, the content of the first positive electrode active material can be greater than or equal to about 85wt%, for example, greater than or equal to about 85.5wt%, or greater than or equal to about 86wt%. In one or more embodiments, based on a 100wt% first positive electrode active material layer, the content of the first positive electrode active material can be less than or equal to about 90wt%, for example, less than or equal to about 89wt%, less than or equal to about 88.5wt%, less than or equal to about 88wt%, or less than or equal to about 87wt%. Within the foregoing range, it may be more advantageous or beneficial to ensure or provide bending safety.

[0047] For example, based on a 100wt% second positive electrode active material layer, the content of the second positive electrode active material can be greater than or equal to about 91wt%, for example, greater than or equal to about 93wt%, or greater than or equal to about 95wt%. In one or more embodiments, based on a 100wt% second positive electrode active material layer, the content of the second positive electrode active material can be less than or equal to about 99.9wt%, for example, less than or equal to about 99.5wt%, less than or equal to about 99wt%, or less than or equal to about 98.7wt%. Within the foregoing range, high capacity (e.g., electrical capacity) characteristics of the rechargeable lithium battery can be effectively or appropriately ensured or provided.

[0048] For example, based on a 100wt% total positive electrode active material layer, the total content (e.g., amount) of the first and second positive electrode active materials can be greater than or equal to about 95wt%. In one or more embodiments, based on a 100wt% total positive electrode active material layer, the total content (e.g., amount) of the first and second positive electrode active materials can be less than or equal to about 98.5wt%. Within the foregoing range, high capacity (e.g., electrical capacity) characteristics of the rechargeable lithium battery can be effectively or appropriately ensured or provided.

[0049] In one or more embodiments, the total loading level of the first positive electrode active material layer and the second positive electrode active material layer can be greater than or equal to about 30 mg / cm³. 2 For example, greater than or equal to approximately 32 mg / cm³ 2 ≥34 mg / cm³ 2 ≥34.85 mg / cm³ 2 Or greater than or equal to approximately 35.10 mg / cm³ 2 In one or more embodiments, the total loading level of the first positive electrode active material layer and the second positive electrode active material layer may be less than or equal to about 40 mg / cm³. 2 For example, less than or equal to approximately 39 mg / cm³ 2 Less than or equal to approximately 38 mg / cm³ 2 Or less than or equal to approximately 37 mg / cm³ 2 Here, the load level can be the amount of electrode active material coated on a unit area of ​​current collector.

[0050] For example, the loading level of the first positive electrode active material layer can be greater than or equal to about 0.1 mg / cm³. 2 For example, greater than or equal to approximately 0.2 mg / cm³ 2 Greater than or equal to approximately 0.5 mg / cm³ 2 or greater than or equal to approximately 0.7 mg / cm³ 2In one or more embodiments, the loading level of the first positive electrode active material layer may be less than or equal to about 4 mg / cm³. 2 For example, less than or equal to about 3.5 mg / cm³ 2 Less than or equal to approximately 3.2 mg / cm³ 2 Less than or equal to approximately 3 mg / cm³ 2 Less than or equal to approximately 2 mg / cm³ 2 Less than or equal to approximately 0.97 mg / cm³ 2 Less than or equal to approximately 0.90 mg / cm³ 2 or less than or equal to approximately 0.75 mg / cm³ 2 In one or more embodiments, the loading level of the second positive electrode active material layer may be greater than or equal to about 29.9 mg / cm³. 2 For example, greater than or equal to approximately 30 mg / cm³ 2 ≥32 mg / cm 2 ≥34 mg / cm³ 2 ≥34.3 mg / cm 2 Or greater than or equal to approximately 34.35 mg / cm³ 2 In one or more embodiments, the loading level of the second positive electrode active material layer may be less than or equal to about 36 mg / cm³. 2 For example, less than or equal to approximately 35.5 mg / cm³ 2 Less than or equal to approximately 35 mg / cm³ 2 Or less than or equal to approximately 34.5 mg / cm³ 2 For a positive electrode that meets or has the aforementioned range, it can be used to realize a rechargeable lithium battery with excellent or suitable safety, high capacity (e.g., electrical capacity) and high energy density.

[0051] In one or more embodiments, the average thickness of the first positive electrode active material layer may be greater than or equal to about 0.5 μm, for example, greater than or equal to about 0.8 μm, greater than or equal to about 1 μm, greater than or equal to about 1.5 μm, or greater than or equal to about 2 μm. In one or more embodiments, the average thickness of the first positive electrode active material layer may be less than or equal to about 10 μm, less than or equal to about 8 μm, less than or equal to about 7 μm, less than or equal to about 6 μm, or less than or equal to about 4 μm. This can advantageously or beneficially ensure excellent or suitable battery safety and reduce energy loss.

[0052] For example, the average thickness of the second positive electrode active material layer can be greater than or equal to about 80 μm, for example, greater than or equal to about 90 μm, or greater than or equal to about 95 μm. In one or more embodiments, the average thickness of the second positive electrode active material layer can be less than or equal to about 200 μm, for example, less than or equal to about 180 μm, less than or equal to about 150 μm, or less than or equal to about 130 μm. In one or more embodiments, high capacity (e.g., electrical capacity) characteristics of the rechargeable lithium battery can be effectively or appropriately ensured or provided.

[0053] For example, the average thickness of the second positive electrode active material layer can be about 4 times or more the average thickness of the first positive electrode active material layer, such as about 5 times or more, about 8 times or more, about 10 times or more, about 15 times or more, about 20 times or more, about 25 times or more, about 30 times or more, or about 40 times or more. In one or more embodiments, the average thickness of the second positive electrode active material layer can be about 60 times or less the average thickness of the first positive electrode active material layer, such as about 55 times or less, about 50 times or less, or about 48 times or less. Within the foregoing range, the safety and high-capacity (e.g., charge capacity) characteristics of the rechargeable lithium battery can be maximized or enhanced.

[0054] In one or more embodiments, based on the total amount of 100 wt% of the positive electrode active material layer, the content (e.g., amount) of the first positive electrode active material layer can be greater than or equal to about 0.5 wt%, for example, greater than or equal to about 0.8 wt%, greater than or equal to about 1 wt%, greater than or equal to about 1.5 wt%, or greater than or equal to about 2 wt%. In one or more embodiments, based on the total amount of 100 wt% of the positive electrode active material layer, the content (e.g., amount) of the first positive electrode active material layer can be less than or equal to about 5 wt%, less than or equal to about 4.5 wt%, less than or equal to about 4 wt%, less than or equal to about 3.5 wt%, less than or equal to about 3 wt%, or less than or equal to about 2.8 wt%. In one or more embodiments, the total amount of the positive electrode active material layer represents the total content (e.g., amount) of the first and second positive electrode active material layers. If (e.g., when) the foregoing ranges are met, the effect of ensuring or providing excellent or suitable adhesion and safety of the positive electrode current collector can be maximized or enhanced.

[0055] For example, based on a total positive electrode active material layer of 100 wt%, the content (e.g., amount) of the second positive electrode active material layer can be greater than or equal to about 95 wt%, for example, greater than or equal to about 95.5 wt%, greater than or equal to about 96 wt%, greater than or equal to about 96.5 wt%, greater than or equal to about 97 wt%, or greater than or equal to about 97.2 wt%. In one or more embodiments, based on a total positive electrode active material layer of 100 wt%, the content (e.g., amount) of the second positive electrode active material layer can be less than or equal to about 99.5 wt%, for example, less than or equal to about 99.2 wt%, less than or equal to about 99 wt%, less than or equal to about 98.5 wt%, or less than or equal to about 98 wt%. If (e.g., when) the foregoing ranges are met, the effect of ensuring or providing excellent or suitable safety and capacity (e.g., capacitance) can be maximized or enhanced.

[0056] In one or more embodiments, the first positive electrode active material layer and the second positive electrode active material layer may each further include a binder, a conductive (e.g., electrically conductive) material and / or a combination thereof (e.g., any suitable combination).

[0057] adhesive Binders can improve or enhance the adhesion properties between positive electrode active material particles and / or between positive electrode active material particles and positive electrode current collector. Examples of binders may include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resins, (meth)acrylate resins, polyester resins and / or nylon.

[0058] conductive materials Conductive (e.g., electrically conductive) materials (e.g., electronic conductors) may be included to provide electrode conductivity, and any suitable conductive material may be used as a conductive material unless it causes a chemical change in the rechargeable lithium battery constituting it (e.g., unless it causes an undesirable chemical change in the rechargeable lithium battery). Examples of conductive (e.g., electrically conductive) materials may include: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, carbon nanotubes, etc.; metallic materials including metal powders and / or metal fibers of copper, nickel, aluminum, silver, etc.; conductive (e.g., electrically conductive) polymers such as polyphenylene and / or derivatives thereof; and / or mixtures thereof (e.g., any suitable mixtures thereof).

[0059] Based on a 100 wt% first positive electrode active material layer, the total content (e.g., amount) of conductive (e.g., electrically conductive) material and binder in the first positive electrode active material layer can be greater than or equal to about 10 wt%, for example, greater than or equal to about 11 wt%, greater than or equal to about 11.5 wt%, greater than or equal to about 12 wt%, or greater than or equal to about 13 wt%. In one or more embodiments, based on a 100 wt% first positive electrode active material layer, the total content (e.g., amount) of conductive (e.g., electrically conductive) material and binder in the first positive electrode active material layer can be less than or equal to about 15 wt%, for example, less than or equal to about 14.5 wt%, or less than or equal to about 14 wt%. Within the foregoing range, it may be more advantageous or beneficial to ensure or provide excellent or suitable flexural safety.

[0060] For example, based on a 100 wt% second positive electrode active material layer, the total content (e.g., amount) of conductive (e.g., electrically conductive) material and binder in the second positive electrode active material layer can be greater than or equal to about 0.1 wt%, for example, greater than or equal to about 0.5 wt%, greater than or equal to about 1.0 wt%, or greater than or equal to about 1.3 wt%. In one or more embodiments, based on a 100 wt% second positive electrode active material layer, the total content (e.g., amount) of conductive (e.g., electrically conductive) material and binder in the second positive electrode active material layer can be less than or equal to about 9 wt%, for example, less than or equal to about 7 wt%, less than or equal to about 5 wt%, or less than or equal to about 3 wt%. Within the foregoing range, it may be more advantageous or beneficial to ensure safety and capacity (e.g., electrical capacity).

[0061] carbon coating In one or more embodiments, a carbon coating layer may be included or provided between the positive electrode current collector and the first positive electrode active material layer. The carbon coating layer according to one or more embodiments may include carbon-based materials such as artificial graphite, natural graphite, carbon black, acetylene black, Ketjen black, Denka black, and / or combinations thereof (e.g., any suitable combination). If such a carbon coating layer is included or provided, the internal resistance (e.g., resistance) of the electrode (e.g., the positive electrode) may be reduced (or the degree or occurrence of reducing the internal resistance (e.g., resistance) of the electrode (e.g., the positive electrode), and the capacity (e.g., capacity) characteristics and safety of the rechargeable lithium battery may be further improved or enhanced.

[0062] For example, the carbon coating may further include an adhesive, and the adhesive may include polymers comprising polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, polyacrylamide, polyimide, polyacrylic acid, and / or combinations thereof (e.g., any suitable). In one or more embodiments, the carbon coating may include a fluorinated adhesive, such as polyvinylidene fluoride. If, for example, the carbon coating according to one or more embodiments uses or includes an adhesive as described in one or more embodiments, the carbon coating may ensure or provide an appropriate or suitable level of adhesion.

[0063] For example, the average thickness of the carbon coating may be greater than or equal to about 0.5 μm, greater than or equal to about 1 μm, or greater than or equal to about 1.5 μm. In one or more embodiments, the average thickness of the carbon coating may be less than or equal to about 3 μm, less than or equal to about 2.5 μm, or less than or equal to about 2 μm. Within the foregoing range, the effect of including the carbon coating can be maximized or enhanced.

[0064] For example, a carbon coating can be manufactured by preparing a carbon composition by mixing a binder and a carbonaceous material as described in one or more embodiments in a solvent, and then coating the carbon composition onto a positive electrode current collector. In one or more embodiments, the mixing ratio of the carbonaceous material and the binder, by weight, can be in the range of about 60:40 to about 90:10. Within the foregoing range, the excellent or suitable adhesion ensured or provided by the binder and the excellent or suitable effects of reduced internal resistance (e.g., electrical resistance) and improved or enhanced cycle life characteristics ensured by the carbonaceous material can be coordinated or synergistic with each other. In one or more embodiments, there are no particular limitations on the solvent; however, as an example, N-methylpyrrolidone can be used.

[0065] The positive electrode current collector may include Al, but the embodiments disclosed herein are not limited thereto.

[0066] Rechargeable lithium batteries In one or more embodiments, a rechargeable lithium battery may include a positive electrode, a negative electrode, and / or an electrolyte as described in one or more embodiments. For example, a rechargeable lithium battery may include a positive electrode, a negative electrode, a separator between the positive and negative electrodes, and an electrolyte as described in one or more embodiments.

[0067] Rechargeable lithium batteries can be classified according to their shape, such as cylindrical, prismatic, pouch-shaped, and coin-shaped. Figures 1 to 4These are schematic diagrams illustrating rechargeable lithium batteries according to one or more embodiments, wherein, Figure 1 It is a cylindrical battery. Figure 2 It is a prismatic battery, and Figure 3 and Figure 4 All are pouch-shaped batteries. (See reference) Figures 1 to 4 The rechargeable lithium battery 100 may include an electrode assembly 40 having a separator 30 between a positive electrode 10 and a negative electrode 20, and a housing 50 therein housing the electrode assembly 40. The positive electrode 10, negative electrode 20, and separator 30 may be impregnated with an electrolyte. The rechargeable lithium battery 100 may include a sealing member 60 for sealing the housing 50, such as... Figure 1 As shown. In one or more embodiments, in Figure 2 In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive electrode terminal 12, a negative electrode lead connector 21, and / or a negative electrode terminal 22. For example... Figure 3 and Figure 4 As shown, the rechargeable lithium battery 100 may include electrode terminals 70 (e.g., positive electrode terminal 71 and negative electrode terminal 72) that serve as or are used as electrical paths for guiding current formed or provided in the electrode assembly 40 to the outside.

[0068] The rechargeable lithium battery according to one or more embodiments can be rechargeable at high voltage or adapted to operate at high voltage. For example, the charging voltage of the rechargeable lithium battery can be greater than or equal to about 4.45V, such as about 4.45V to about 4.7V, about 4.45V to about 4.6V, or about 4.45V to about 4.55V, etc. Even when charged at high voltage, the rechargeable lithium battery according to one or more embodiments can achieve high capacity (e.g., electrical capacity) characteristics by applying or providing the positive electrode active material according to one or more embodiments.

[0069] negative electrode The negative electrode may include a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector, and the negative electrode active material layer may include a negative electrode active material and may further include a binder, a conductive (e.g., electrically conductive) material and / or a combination thereof (e.g., any suitable combination).

[0070] Negative electrode active material The negative electrode active material may include materials that can reversibly insert / deintercalate lithium ions, lithium metal, lithium metal alloys, materials capable of doping / dedoping lithium, and / or transition metal oxides.

[0071] Materials that can reversibly embed / extract lithium ions can include, for example, crystalline carbon, amorphous (e.g., non-crystalline) carbon, and / or a combination thereof (e.g., any suitable combination) as carbonaceous negative electrode active materials. The crystalline carbon can be irregular (e.g., substantially irregular), and / or flaky (e.g., substantially flaky), lamellar (e.g., substantially lamellar), spherical (e.g., substantially spherical), and / or fibrous (e.g., substantially fibrous) natural graphite and / or artificial graphite. The amorphous (e.g., non-crystalline) carbon can be soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0072] The lithium metal alloy can include an alloy of lithium and a metal selected from sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), Mg, Ca, Sr, Si, antimony (Sb), lead (Pb), indium (In), zinc (Zn), Ba, radium (Ra), germanium (Ge), aluminum (Al), and tin (Sn).

[0073] Materials that can be doped / undoped with lithium can be Si-based negative electrode active materials and / or Sn-based negative electrode active materials. The Si-based negative electrode active materials can include silicon, silicon-carbon composites, SiO x (0 < x ≤ 2), Si-Q alloys (where Q can be an element selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and / or a combination thereof (e.g., any suitable combination), e.g., Mg, Ca, Sr, Ba, Ra, scandium (Sc), yttrium (Y), Ti, Zr, hafnium (Hf), rutherfordium (Rf), V, Nb, tantalum (Ta), (Db), Cr, Mo, W, (Sg), technetium (Tc), rhenium (Re), (Bh), Fe, Pb, ruthenium (Ru), osmium (Os), hassium (Hs), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), Zn, cadmium (Cd), B, Al, gallium (Ga), Sn, In, thallium (Tl), germanium (Ge), P, arsenic (As), Sb, bismuth (Bi), S, selenium (Se), tellurium (Te), polonium (Po), and / or (e.g., any suitable combination thereof) or a combination thereof. The Sn-based negative electrode active materials can be Sn, SnO k (0 < k ≤ 2) (e.g., SnO2), Sn alloys, and / or a combination thereof (e.g., any suitable combination).

[0074] The silicon-carbon composite can be a composite of silicon and amorphous (e.g., non-crystalline) carbon. The average particle size (D 50)(It) can be, for example, from about 0.5 μm to about 20 μm. According to one or more embodiments, the silicon-carbon composite can be in the form of silicon particles and amorphous (e.g., non-crystalline) carbon coated on the surface of the silicon particles. For example, it can include secondary particles (cores) in which primary silicon particles are assembled and / or an amorphous (e.g., non-crystalline) carbon coating layer (shells) on the surface of the secondary particles. The amorphous (e.g., non-crystalline) carbon can also be between the primary silicon particles. For example, the primary silicon particles can be coated with amorphous (e.g., non-crystalline) carbon. The secondary particles can be dispersed in an amorphous (e.g., non-crystalline) carbon matrix.

[0075] The silicon-carbon composite can further include crystalline carbon. For example, the silicon-carbon composite can include a core and an amorphous (e.g., non-crystalline) carbon coating layer on the surface of the core, and the core includes crystalline carbon and / or silicon particles. The crystalline carbon can be artificial graphite, natural graphite, and / or a combination thereof (e.g., any suitable combination). The amorphous (e.g., non-crystalline) carbon can include soft carbon and / or hard carbon, mesophase pitch carbonized products, and / or calcined coke.

[0076] If (e.g., when) the silicon-carbon composite includes silicon and amorphous (e.g., non-crystalline) carbon, based on 100 wt% of the silicon-carbon composite, the silicon content (e.g., amount) can be from about 10 wt% to about 50 wt%, and the content (e.g., amount) of the amorphous (e.g., non-crystalline) carbon can be from about 50 wt% to about 90 wt%. In one or more embodiments, if (e.g., when) the composite includes silicon, amorphous (e.g., non-crystalline) carbon, and / or crystalline carbon, based on 100 wt% of the silicon-carbon composite, the silicon content (e.g., amount) can be from about 10 wt% to about 50 wt%, the content (e.g., amount) of the crystalline carbon can be from about 10 wt% to about 70 wt%, and the content (e.g., amount) of the amorphous (e.g., non-crystalline) carbon can be from about 20 wt% to about 40 wt%.

[0077] In one or more embodiments, the thickness of the amorphous (e.g., non-crystalline) carbon coating layer can be from about 5 nm to about 100 nm. The average particle size (D 50 ) of the silicon particles (e.g., primary particles) can be from about 10 nm to about 1 μm or from about 10 nm to about 200 nm. The silicon particles can exist as elemental silicon, in the form of a silicon alloy, and / or in an oxidized form. The oxidized form of silicon can be represented by SiO x (0 < x ≤ 2). In one or more embodiments, the atomic content (e.g., amount) ratio of Si:O representing the degree of oxidation can be from about 99:1 to about 33:67. As used herein, if (e.g., when) no other definition is provided, the average particle size (D 50 ) refers to the diameter of the particles in which the cumulative volume in the particle distribution is about 50 volume %.

[0078] Si-based and / or Sn-based negative electrode active materials can be mixed with carbon-based negative electrode active materials. If (for example, when) Si-based or Sn-based negative electrode active materials are mixed and used with carbon-based negative electrode active materials, the mixing ratio can be from about 1:99 to about 90:10 by weight.

[0079] adhesive The binder can act as or be used to ensure good or proper adhesion between the negative electrode active material particles and / or to the negative electrode current collector. The binder can be a non-aqueous (e.g., water-insoluble) binder, an aqueous (e.g., water-soluble) binder, a dry binder, and / or a combination thereof (e.g., any suitable combination).

[0080] Non-aqueous (e.g., water-insoluble) adhesives may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide and / or any suitable combination thereof.

[0081] Waterborne (e.g., water-soluble) adhesives may include styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepoxychloropropane, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol and / or (e.g., any suitable) combinations thereof.

[0082] If (for example, when) an aqueous (e.g., water-soluble) binder is used as a negative electrode binder, it may further include a cellulose-based compound capable of imparting or increasing viscosity. As a cellulose-based compound, one or more selected from carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and their alkali metal salts may be mixed and used. The alkali metal may be Na, K, or lithium (Li).

[0083] Dry binders can be polymeric materials that can be transformed or processed into fibers, and can be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide and / or combinations thereof (e.g., any suitable combination).

[0084] conductive materials Conductive materials may be included to provide electrode conductivity, and any suitable conductive material may be used as a conductive material unless it causes a chemical change (e.g., an undesirable chemical change in a rechargeable lithium battery). Examples of conductive (e.g., electrically conductive) materials may include: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, carbon nanotubes, etc.; metallic materials including metal powders and / or metal fibers of copper, nickel, aluminum, silver, etc.; conductive (e.g., electrically conductive) polymers such as polyphenylene and / or derivatives thereof; and / or mixtures thereof (e.g., any suitable mixtures thereof).

[0085] Based on a 100wt% negative electrode active material layer, the content (e.g., amount) of the negative electrode active material can be from about 95wt% to about 99.5wt%, and based on the 100wt% negative electrode active material layer, the content (e.g., amount) of the binder can be from about 0.5wt% to about 5wt%. For example, the negative electrode active material layer may include about 90wt% to about 99wt% of the negative electrode active material, about 0.5wt% to about 5wt% of the binder, and about 0.5wt% to about 5wt% of the conductive (e.g., electrically conductive) material.

[0086] current collector The negative electrode current collector may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), and / or alloys thereof, and may be in the form of foil, sheet, and / or foam. The thickness of the negative electrode current collector may be, for example, about 1 μm to about 20 μm, about 5 μm to about 15 μm, or about 7 μm to about 10 μm.

[0087] electrolytes The electrolyte used in rechargeable lithium batteries can be an electrolyte that may include non-aqueous (e.g., water-insoluble) organic solvents and / or lithium salts.

[0088] Non-aqueous (e.g., water-insoluble) organic solvents can act as or be used as a medium for transporting ions involved in the electrochemical reactions of rechargeable lithium batteries. Non-aqueous (e.g., water-insoluble) organic solvents can be carbonate solvents, ester solvents, ether solvents, ketone solvents and / or alcohol solvents, aprotic solvents and / or (e.g., any suitable) combinations.

[0089] Carbonate solvents can include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butyl carbonate (BC), etc. Ester solvents can include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolactone, mevalonolactone, valproic acid lactone, caprolactone, etc. Ether solvents can include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Ketone solvents can include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., and aprotic solvents may include: nitriles, such as R-CN (wherein R may be a C2 to C20 straight-chain, branched or cyclic hydrocarbon group, and may include double bonds, aromatic rings or ether groups, etc.); amides, such as dimethylformamide; dioxolane, such as 1,3-dioxolane, 1,4-dioxolane, etc.; sulfolane; etc.

[0090] Non-aqueous (e.g., water-insoluble) organic solvents can be used alone or in mixtures of two or more types (or kinds) (e.g., any suitable), and if (e.g., when) two or more types (or kinds) are used in a mixture, the mixing ratio can be appropriately or suitably adjusted according to desired or suitable battery performance, which is generally available to those skilled in the art.

[0091] When using carbonate solvents, cyclic carbonates and chain (e.g., non-cyclic) carbonates can be mixed and used, and the cyclic carbonates and chain (e.g., non-cyclic) carbonates can be mixed in a volume ratio of about 1:1 to about 1:9.

[0092] Non-aqueous (e.g., water-insoluble) organic solvents may further include aromatic hydrocarbon organic solvents. For example, carbonate solvents and aromatic hydrocarbon organic solvents may be mixed and used in a volume ratio of about 1:1 to about 30:1.

[0093] The electrolyte may also include ethylene ethyl carbonate, vinylene carbonate and / or ethylene carbonate compounds to improve or enhance the cycle life of the battery (e.g., a rechargeable lithium battery).

[0094] Examples of ethylene carbonate compounds may include fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, and / or cyanoethylene carbonate.

[0095] Lithium salts dissolved in organic solvents can supply or provide lithium ions in rechargeable lithium batteries, enabling basic operation and improving or enhancing lithium ion transport between the positive and negative electrodes. Examples of lithium salts may include those selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide; LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 At least one of the following: (SO2) (where x and y can be integers from 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0096] The concentration of lithium salt can be in the range of about 0.1 M to about 2.0 M. If (for example, when) the concentration of lithium salt is within the above range, the electrolyte can have appropriate or suitable ionic conductivity and viscosity, thus achieving excellent or suitable performance, and lithium ions can move efficiently or appropriately.

[0097] diaphragm Depending on the type (or category) of the rechargeable lithium battery, the separator can be located between the positive and negative electrodes. The separator may include polyethylene, polypropylene, polyvinylidene fluoride, and / or two or more layers of multilayer membranes, and / or mixed multilayer membranes, such as polyethylene / polypropylene double-layer membranes, polyethylene / polypropylene / polyethylene triple-layer membranes, polypropylene / polyethylene / polypropylene triple-layer membranes, etc.

[0098] The membrane may include a porous substrate and / or a coating layer comprising organic materials, inorganic materials and / or combinations thereof (e.g., any suitable combination) on one or both surfaces (e.g., two opposing surfaces) of the porous substrate.

[0099] The porous substrate can be selected from polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetal, polyamide, polyimide, polycarbonate, polyetherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fiber, polytetrafluoroethylene (e.g., Teflon). TM Polymer films of any one of the polymers and / or copolymers and / or mixtures of two or more of them.

[0100] The porous substrate can have a thickness of about 1 μm to about 40 μm, for example, about 1 μm to about 30 μm, about 1 μm to about 20 μm, about 5 μm to about 15 μm, or about 10 μm to about 15 μm.

[0101] Organic materials may include (meth)acrylic acid copolymers, which include a first structural unit and / or a second structural unit, the first structural unit being derived from (meth)acrylamide, and the second structural unit including at least one structural unit selected from structural units derived from (meth)acrylic acid and / or (meth)acrylates and structural units derived from (meth)acrylamide sulfonic acid and / or its salts.

[0102] Inorganic materials may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and / or any suitable combination thereof, but embodiments of this disclosure are not limited thereto. The average particle size (D) of the inorganic particles... 50 The wavelength range can be from about 1 nm to about 2000 nm, for example, from about 100 nm to about 1000 nm, or from about 100 nm to about 700 nm.

[0103] Organic and inorganic materials can be mixed in a coating layer, and / or coating layers comprising organic materials and / or coating layers comprising inorganic materials can be stacked.

[0104] The thickness of the coating can be from about 0.5 μm to about 20 μm, for example, from about 1 μm to about 10 μm or from about 1 μm to about 5 μm.

[0105] Examples and comparative examples of this disclosure are described in more detail below. However, the following examples are merely illustrative of this disclosure, and embodiments of this disclosure are not limited to the following examples.

[0106] Example 1 1. Manufacturing of the positive electrode A slurry was prepared by dispersing 80 wt% Denca Black and 20 wt% polyvinylidene fluoride in N-methylpyrrolidone solvent to form a carbon coating layer. The slurry for forming the carbon coating layer was then coated onto an aluminum film current collector, dried, and compressed to form a carbon coating layer on the positive electrode (i.e., the aluminum film) current collector. Here, the carbon coating layer loading was 0.5 g / m². 2 .

[0107] On the carbon coating layer, by using an average particle size (D) of 87 wt% 50A slurry was prepared by mixing 1 μm LiFePO4, 5 wt% carbon nanotube conductive material, and 8 wt% polyvinylidene fluoride binder. This slurry was coated, then dried and compressed to form or provide a first positive electrode active material layer. Here, the first positive electrode active material layer has a concentration of 0.80 mg / cm³. 2 The load level and average thickness of 2μm.

[0108] Subsequently, by using 98.7 wt% of the average particle size (D) 50 A slurry was prepared by mixing 17 μm LiCoO2, 0.3 wt% carbon nanotube conductive material, and 1 wt% polyvinylidene fluoride binder. The slurry was coated onto a first positive electrode active material layer, then dried and compressed to form or provide a second positive electrode active material layer. Here, the second positive electrode active material layer has a concentration of 34.30 mg / cm³. 2 The load level and average thickness of 95.5 μm.

[0109] Here, based on a total amount of 100wt% positive electrode active material layer, the content (e.g., amount) of the first positive electrode active material layer is 2.3wt%, and the content (e.g., amount) of the second positive electrode active material layer is 97.7wt%.

[0110] In one or more embodiments, based on 100 wt% of the total amount of the positive electrode active material layer, the content (e.g., amount) of the first positive electrode active material is 2.0 wt%, and the content (e.g., amount) of the second positive electrode active material is 96.5 wt%. Therefore, the weight ratio of the second positive electrode active material to the first positive electrode active material is 48.3.

[0111] In view of the above, in order to manufacture the positive electrode, a carbon coating layer is formed or provided on the aluminum film current collector using a slurry composed of 80 wt% Denca Black and 20 wt% polyvinylidene fluoride in N-methylpyrrolidone solvent, achieving a loading level of 0.5 g / m². On this carbon coating layer, a first positive electrode active material layer is created using a slurry of 87 wt% LiFePO4, 5 wt% carbon nanotubes, and 8 wt% polyvinylidene fluoride, resulting in a layer with a loading level of 0.80 mg / cm² and a thickness of 2 μm. Subsequently, a second positive electrode active material layer is formed using a slurry of 98.7 wt% LiCoO2, 0.3 wt% carbon nanotubes, and 1 wt% polyvinylidene fluoride, achieving a loading level of 34.30 mg / cm². 2 The loading level and thickness are 95.5 μm. The first positive electrode active material layer constitutes 2.3 wt% of the total positive electrode active material layer, and the second positive electrode active material layer constitutes 97.7 wt% of the total positive electrode active material layer, such that the weight ratio of the second positive electrode active material to the first positive electrode active material is 48.3.

[0112] A negative electrode active material slurry was prepared by mixing 97.5 wt% graphite negative electrode active material, 1.5 wt% carboxymethyl cellulose, and 1 wt% styrene-butadiene rubber in an aqueous solvent. The negative electrode active material slurry was coated onto a copper foil current collector, dried, and pressed to manufacture the negative electrode.

[0113] A rechargeable lithium-ion battery cell is manufactured using a positive and negative electrode with a polytetrafluoroethylene separator and an electrolyte prepared by dissolving 1 M LiPF6 in a mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 3:7.

[0114] Example 2 Except that the weight ratio of the second positive electrode active material to the first positive electrode active material is changed to 40 by satisfying Tables 1 to 3 when preparing the positive electrode active material layer, the positive electrode and the rechargeable lithium battery cell are manufactured in essentially the same manner as in Example 1.

[0115] Example 3 Except that the weight ratio of the second positive electrode active material to the first positive electrode active material is changed to 53.7 by satisfying Tables 1 to 3 when preparing the positive electrode active material layer, the positive electrode and the rechargeable lithium battery cell are manufactured in a manner substantially the same as in Method 1 of the example.

[0116] Comparison Example 1 Except that the weight ratio of the second positive electrode active material to the first positive electrode active material is changed to 38.4 by satisfying Tables 1 to 3 when preparing the positive electrode active material layer, the positive electrode and the rechargeable lithium battery cell are manufactured in a manner substantially the same as in Example 1.

[0117] Comparison Example 2 Except that the weight ratio of the second positive electrode active material to the first positive electrode active material is changed to 56.9 by satisfying Tables 1 to 3 when preparing the positive electrode active material layer, the positive electrode and the rechargeable lithium battery cell are manufactured in a manner substantially the same as in Example 1.

[0118] To aid understanding, further design details for the examples and comparative examples are briefly presented in Tables 1 through 3.

[0119] In the positive electrodes of Examples 1 to 3 and Comparative Examples 1 to 3, the loading level and content (e.g., amount) of each positive electrode active material layer are shown in Table 1. In one or more embodiments, in the positive electrodes of Examples 1 to 3 and Comparative Examples 1 to 3, the content (e.g., amount) of each component of the first positive electrode active material layer and the second positive electrode active material layer are shown in Table 2, and the weight ratios of the second positive electrode active material to the first positive electrode active material are summarized in Table 3.

[0120] Table 1

[0121] Table 2

[0122] Table 3

[0123] Evaluation Example 1: Security Evaluation The rechargeable lithium-ion battery cells of Examples 1 to 3 and Comparative Examples 1 to 2 were subjected to cell bending tests in a fully charged state to evaluate stringent safety by measuring the maximum exothermic temperature and checking whether the cell ignited. The results are shown in Table 4. Here, the cell bending test was conducted by charging the rechargeable lithium-ion battery cell to 4.47V at 0.5C, pausing for about 24 hours, and bending the center portion of the cell to 90°.

[0124] Evaluation Example 2: Initial Charge and Discharge Evaluation The rechargeable lithium-ion battery cells of Examples 1 to 3 and Comparative Examples 1 to 2 were charged at a constant current of 0.2C to an upper limit voltage of 4.47V, and then charged at a constant voltage to 0.02C, and then discharged at 0.2C to a cutoff voltage of 3.0V at 25°C for initial charge and discharge. Table 4 shows the initial discharge capacity per gram (g) (mAh / g).

[0125] Table 4

[0126] Referring to the results in Table 4, Comparative Example 1 exhibits a relatively low initial discharge capacity and slightly lower capacity characteristics, while Comparative Example 2 shows ignition in the safety evaluation, which confirms its poor safety.

[0127] Conversely, Examples 1 through 3 did not exhibit ignition in the safety evaluation, thus demonstrating excellent or suitable safety, and also exhibited an initial discharge capacity greater than or equal to 182 mAh / g, thus demonstrating excellent or suitable capacity characteristics.

[0128] The battery manufacturing apparatus, battery management system (BMS) apparatus, and / or any other related apparatus or components according to embodiments of the invention described herein can be implemented using any suitable hardware, firmware (e.g., application-specific integrated circuits), software, or a combination of software, firmware, and hardware. For example, various components of the apparatus may be formed on an integrated circuit (IC) chip or on separate IC chips. Furthermore, various components of the apparatus may be implemented on a flexible printed circuit film, a tape-and-carrier package (TCP), a printed circuit board (PCB), or formed on a substrate. Additionally, various components of the apparatus may be processes or threads executing computer program instructions and interacting with other system components to perform the various functions described herein, running on one or more processors in one or more computing devices. The computer program instructions are stored in memory, which may be implemented in a computing device using standard memory devices, such as random access memory (RAM). The computer program instructions may also be stored in other non-transitory computer-readable media, such as CD-ROMs, flash drives, etc. Furthermore, those skilled in the art will recognize that, without departing from the scope of this disclosure, the functions of various computing devices may be combined or integrated into a single computing device, or the functions of a particular computing device may be distributed across one or more other computing devices.

[0129] It will be understood by those skilled in the art that, in view of the whole of this disclosure, various suitable features of the various embodiments of this disclosure may be combined in part or in whole or in combination with each other, and may be technically interlocked and operated in various suitable ways, and unless otherwise stated or implied, the various embodiments may be implemented independently or in combination with each other in any suitable manner.

[0130] While the subject matter of this disclosure has been described in conjunction with what are now considered practical exemplary embodiments, it will be understood that this disclosure is not limited to the disclosed embodiments. In one or more embodiments, this disclosure is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the appended claims and their equivalents. Therefore, it will be understood that the foregoing one or more embodiments are illustrative in all respects and not restrictive.

[0131] Figure Labels 100: Rechargeable lithium battery 10: Positive electrode 11: Positive electrode lead connector 12: Positive electrode terminal 20: Negative electrode 21: Negative electrode lead connector 22: Negative electrode terminal 30: Diaphragm 40: Electrode assembly 50: Casing 60: Sealing component 70: Electrode connector 71: Positive electrode connector 72: Negative electrode connector 201: First positive electrode active material 202: Second positive electrode active material 300: Positive electrode current collector 301: First positive electrode active material layer 302: Second positive electrode active material layer.

Claims

1. A positive electrode, the positive electrode comprising: Positive electrode current collector; A first positive electrode active material layer is disposed on the positive electrode current collector and includes the first positive electrode active material; as well as A second positive electrode active material layer is disposed on the first positive electrode active material layer and includes the second positive electrode active material. in, The first positive electrode active material includes lithium iron phosphate compounds. The second positive electrode active material includes lithium cobalt oxide, and The weight ratio of the second positive electrode active material to the first positive electrode active material is 40 to 55.

2. The positive electrode according to claim 1, wherein: The average particle size of the first positive electrode active material is smaller than the average particle size of the second positive electrode active material.

3. The positive electrode according to claim 1, wherein: The average particle size of the second positive electrode active material is 4 to 50 times that of the average particle size of the first positive electrode active material.

4. The positive electrode according to claim 1, wherein: The average particle size of the first positive electrode active material is 0.1 μm to 5 μm.

5. The positive electrode according to claim 1, wherein: The average particle size of the second positive electrode active material is 8 μm to 30 μm.

6. The positive electrode according to claim 1, wherein: Based on 100wt% of the first positive electrode active material layer, the amount of the first positive electrode active material is 85wt% to 90wt%.

7. The positive electrode according to claim 1, wherein: Based on 100 wt% of the second positive electrode active material layer, the amount of the second positive electrode active material is 91 wt% to 99.9 wt%.

8. The positive electrode according to claim 1, wherein: The average thickness of the first positive electrode active material layer is 0.5 μm to 10 μm.

9. The positive electrode according to claim 1, wherein: The average thickness of the second positive electrode active material layer is 80 μm to 200 μm.

10. The positive electrode according to claim 1, wherein: The average thickness of the second positive electrode active material layer is 4 to 60 times the average thickness of the first positive electrode active material layer.

11. The positive electrode according to claim 1, wherein: The lithium iron phosphate compounds are represented by chemical formula 1: Chemical Formula 1 Li a1 Fe x1 M 1 y1 M 2 z1 (PO 4-b1 )X b1 ,and In chemical formula 1, 0.9 ≤ a1 ≤ 1.8, 0.1 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.7, 0 ≤ z1 ≤ 0.7, 0.9 ≤ x1 + y1 + z1 ≤ 1.1, and 0 ≤ b1 ≤ 0.1, M 1 and M 2 Each of them is independently Al, B, Ba, Ca, Ce, Co, Cr, Mg, Mn, Mo, Nb, Si, Sr, Ti, V, W, Zr or a combination thereof, and X is F, P, S or a combination thereof.

12. The positive electrode according to claim 1, wherein: The lithium-cobalt oxide is represented by chemical formula 2: Chemical formula 2 Li a2 Co x2 M 3 y2 M 4 z2 O 2-b2 X b2 ,and In chemical formula 2, 0.9 ≤ a² ≤ 1.8, 0.3 ≤ x² ≤ 1, 0 ≤ y² ≤ 0.7, 0 ≤ z² ≤ 0.7, 0.9 ≤ x² + y² + z² ≤ 1.1, and 0 ≤ b² ≤ 0.1, M 3 and M 4 Each of them is independently Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mn, Mo, Nb, Si, Sr, Ti, V, W, Zr or a combination thereof, and X is F, P, S or a combination thereof.

13. The positive electrode according to claim 1, wherein: Based on 100 mol% of total metals excluding lithium, lithium cobalt oxides have a cobalt content of greater than or equal to 60 mol%.

14. The positive electrode according to claim 1, wherein: Based on the total amount of the first positive electrode active material layer and the second positive electrode active material layer of 100wt%, the content of the first positive electrode active material layer is 0.5wt% to 5wt%.

15. The positive electrode according to claim 1, wherein: Based on the total amount of the first positive electrode active material layer and the second positive electrode active material layer of 100wt%, the content of the second positive electrode active material layer is 95wt% to 99.5wt%.

16. The positive electrode according to claim 1, wherein: Based on 100wt% of the first positive electrode active material layer, the total content of conductive material and binder in the first positive electrode active material layer is 10wt% to 15wt%.

17. The positive electrode according to claim 1, wherein: Based on 100 wt% of the second positive electrode active material layer, the total content of conductive material and binder in the second positive electrode active material layer is from 0.1 wt% to 9 wt%.

18. The positive electrode according to claim 1, wherein: A carbon coating layer is also included between the positive electrode current collector and the first positive electrode active material layer.

19. The positive electrode according to claim 1, wherein: The loading level of the first positive electrode active material layer is 0.1 mg / cm³. 2 Up to 4 mg / cm 2 ,and The loading level of the second positive electrode active material layer is 29.9 mg / cm³. 2 Up to 36 mg / cm 2 .

20. A rechargeable lithium battery, said rechargeable lithium battery comprising: The positive electrode according to claim 1; negative electrode; as well as Electrolytes.

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