KR20240003646A - Positive electrode and method for prepraring positive electrode - Google Patents

Abstract

The present invention relates to a positive electrode active material, which is manufactured through a single process synthesis, has a primary particle size of 1 ㎛ or more, and has a spinel structure inserted into the layered structure, improving the initial efficiency and stability of a lithium secondary battery containing it. It relates to a positive electrode active material that can be used, a method of manufacturing the same, and a positive electrode and lithium secondary battery containing the same.

Description

Cathode active material and method for manufacturing cathode active material {POSITIVE ELECTRODE AND METHOD FOR PREPRARING POSITIVE ELECTRODE}

The present invention relates to a positive electrode active material, a method of manufacturing the same, a positive electrode containing the same, and a lithium secondary battery.

Recently, the demand for high-capacity secondary batteries has increased due to technological developments such as electric vehicles, and accordingly, research on positive electrodes using high nickel (High Ni) positive electrode active materials with excellent capacity characteristics has been actively conducted. However, in the case of high nickel positive electrode active materials, there is a problem of increased manufacturing costs due to the use of cobalt and excessive nickel.

Accordingly, recently, high manganese (High Mn) cathode materials with a manganese content of 50 mol% have been developed. This is attracting attention as a low-cost cathode material capable of developing high capacity at high voltage due to its high manganese content and oxygen redox reaction. However, the high manganese cathode material has a problem in that the efficiency is significantly reduced in the first formation drive when driven at high voltage, and the capacity retention rate and stability are reduced compared to the high nickel cathode active material.

To solve this problem, “Spinel-embedded lithium-rich oxide composites for Li-ion batteries”, Journal of Power Sources, 360 (2017), 453-459 (Non-patent Document 1) and “Spinel/Layered Heterostructured Cathode Mateiral” for High-Capacity and High-Rate Li-Ion Batteries", ADVANCED MATERIALS, 2013, 25, 3722-3726 (Non-Patent Document 2) presents a high manganese positive electrode active material containing a spinel structure. However, in the case of Non-Patent Documents 1 and 2, after forming the NiMn(OH) ₂ precursor by precipitation, a high manganese positive electrode active material containing a spinel structure is manufactured by additionally adding a manganese precursor, or expensive cobalt is used when synthesizing the precursor. After manufacturing a high manganese cathode active material by adding a precursor, a spinel structure is additionally introduced to manufacture a high manganese cathode active material containing a spinel structure, which ultimately causes an increase in costs due to the process and raw materials. In addition, in the case of particles manufactured by a precipitation method based on co-precipitation, the particle size tends to be manufactured only at a maximum size of less than 1 ㎛, which is caused by problems with rolling density, particle breakage, and subsequent reliability problems during anode production. It becomes the cause.

“Spinel-embedded lithium-rich oxide composites for Li-ion batteries”, Journal of Power Sources, 360 (2017), 453-459 “Spinel/Layered Heterostructured Cathode Mateiral for High-Capacity and High-Rate Li-Ion Batteries”, ADVANCED MATERIALS, 2013, 25, 3722-3726

The problem to be solved by the present invention is to improve initial efficiency and stability by increasing the primary particle size of the high manganese (or manganese-rich) positive electrode active material and inserting a spinel structure.

In other words, the present invention was developed to solve the problems of the prior art, and when manufacturing a high manganese (or manganese-rich) positive electrode active material, the size of the primary particle is 1 ㎛ or more through a single process synthesis, and the spinel layered structure is used. The purpose is to provide a positive electrode active material with improved initial efficiency and stability and a method for manufacturing the same by manufacturing a high manganese positive electrode active material with an inserted structure.

Additionally, the present invention aims to provide a positive electrode and a lithium secondary battery containing the positive electrode active material.

In order to solve the above problems, the present invention provides a positive electrode active material, a method for manufacturing a positive electrode active material, a positive electrode, and a lithium secondary battery.

(1) The present invention includes a lithium transition metal composite oxide containing lithium, nickel, and manganese, and the lithium transition metal composite oxide includes both a spinel structure and a layered structure, but contains an excess of the layered structure compared to the spinel structure. and provides a positive electrode active material in which the average primary particle diameter is 1 ㎛ or more.

(2) The present invention provides the positive electrode active material according to (1) above, wherein the positive electrode active material is a secondary particle in which a plurality of primary particles are aggregated.

(3) The present invention according to (1) or (2) above, wherein the lithium transition metal complex oxide contains a spinel structure confirmed by Rietveld analysis in a content of 30% or more and less than 50%, and a layered structure of 50%. Provided is a positive electrode active material containing an excess of 70% or less.

(4) The present invention provides the positive electrode active material according to any one of (1) to (3) above, wherein the spinel-structured lithium transition metal complex oxide has an average composition represented by the following formula (1).

[Formula 1]

LiNi _a Mn _b O ₄

In Formula 1, 0.4<a<0.6, 1.4<b<1.6, a+b=2.

(5) The present invention provides the positive electrode active material according to any one of (1) to (4) above, wherein the layered lithium transition metal complex oxide has an average composition represented by the following formula (2).

[Formula 2]

_{LixNiyMnzO2 _ _ _}

In Formula 2, 1.1<x<1.3, 0.1<y<0.3, 0.5<z<0.7, x+y+z=2.

(6) The present invention provides the positive electrode active material according to any one of (1) to (5) above, wherein the lithium transition metal complex oxide has an average composition represented by the following formula (3) as measured by ICP.

[Formula 3]

Li _m Ni _n M n _o O ₂

In Formula 3, 1.12<m<1.14, 0.300<n<0.320, 0.545<o<0.570, m+n+o=2.

(7) The present invention provides the positive electrode active material according to any one of (1) to (6) above, wherein the lithium transition metal complex oxide does not contain cobalt.

(8) The present invention forms a synthetic solution by mixing a lithium raw material and a transition metal precursor including a nickel precursor and a manganese precursor in an aqueous solvent at a temperature of 25°C or more and 100°C or less (S10); and drying and calcining the synthetic solution formed in step (S10) (S20).

(9) The present invention provides a method for producing a positive electrode active material in (8) above, wherein the drying in the step (S20) is carried out by spray drying.

(10) The present invention provides the method for producing a positive electrode active material according to (9) above, wherein during the spray drying, the inlet temperature of the spray drying device is 100°C or more and 200°C or less.

(11) The present invention provides a method for producing a positive electrode active material according to any one of (8) to (10) above, wherein the baking in the step (S20) is performed at a temperature of 450 ℃ or more and 1,000 ℃ or less.

(12) The present invention provides a method for producing a positive electrode active material according to any one of (8) to (11) above, wherein the method for producing a positive electrode active material is performed by one pot synthesis.

(13) The present invention according to any one of (8) to (12) above, wherein the positive electrode active material prepared according to the method for producing the positive electrode active material includes lithium and a lithium transition metal complex oxide containing nickel and manganese, The lithium transition metal complex oxide includes both a spinel structure and a layered structure, but includes an excess of the layered structure compared to the spinel structure, and provides a method for manufacturing a positive electrode active material in which the spinel structure and the layered structure are synthesized simultaneously.

(14) The present invention provides a positive electrode containing the positive electrode active material according to any one of (1) to (7) above.

(15) The present invention provides a lithium secondary battery including the positive electrode according to (12) above.

The positive electrode active material of the present invention is manufactured through a single process synthesis, and the size of the primary particles is 1 ㎛ or more, and the spinel structure is inserted into the layered structure, thereby improving the initial efficiency and stability of the lithium secondary battery containing it.

Figure 1 is an image taken with a scanning electron microscope (SEM) of the positive electrode active material prepared in Example 1 of the present invention.
Figure 2 (a) is XRD data for the positive electrode active material prepared in Example 1 and Comparative Examples 1 and 2 of the present invention, and (b) is XRD data between 30 ° and 55 ° among the XRD data shown in (a). This is XRD data shown by expanding the 2θ range and displaying the peak of the spinel structure.

Hereinafter, the present invention will be described in more detail to facilitate understanding of the present invention.

Terms or words used in the description and claims of the present invention should not be construed as limited to their usual or dictionary meanings, and the inventor should appropriately use the concepts of terms to explain his invention in the best way. Based on the principle of definability, it must be interpreted with meaning and concept consistent with the technical idea of the present invention.

In the present invention, the term 'primary particle' refers to the minimum particle unit that is distinguished as a single lump when the positive electrode active material is observed through a scanning electron microscope (SEM), and may be composed of a plurality of crystal grains.

In the present invention, the term 'secondary particle' refers to a secondary structure formed by agglomerating a plurality of primary particles. The average particle diameter of the secondary particles can be measured using a particle size analyzer.

positive electrode active material

The present invention provides a positive electrode active material.

According to one embodiment of the present invention, the positive electrode active material may be a high manganese positive electrode active material, and as a specific example, it may be a high manganese positive electrode active material with a spinel structure inserted.

According to one embodiment of the present invention, the positive electrode active material includes a lithium transition metal composite oxide containing lithium, nickel, and manganese, and the lithium transition metal composite oxide includes both a spinel structure and a layered structure, but has a spinel structure. It may contain an excessive amount of layered structure, and the average particle diameter of the primary particles may be 1 ㎛ or more. In this way, the positive electrode active material includes both a spinel structure and a layered structure, but includes an excessive amount of the layered structure compared to the spinel structure, thereby preventing a significant decrease in efficiency in the first formation drive. Here, the spinel structure of the positive electrode active material is formed along with the layered structure when manufacturing the positive electrode active material, and is not formed by additionally adding a manganese precursor or adding a spinel structure, and of course, the layered structure is formed into a spinel structure by the first activation process. It is clearly distinguished from the phase change.

According to one embodiment of the present invention, the positive electrode active material may be secondary particles in which a plurality of primary particles are aggregated.

According to one embodiment of the present invention, the contents of the spinel structure and the layered structure of the lithium transition metal complex oxide may be confirmed by Rietveld analysis after XRD measurement. Here, the XRD is an It may have been measured using a diffraction analysis method, and Rietveld analysis may have been confirmed using BRUKER's TOPAS software for the XRD data. Data measured by XRD are relative values and may vary depending on the measuring device and conditions, but the ratio between peak intensities is an absolute value and does not change depending on the measuring device and conditions.

According to an embodiment of the present invention, the lithium transition metal complex oxide contains a spinel structure confirmed by Rietveld analysis in an amount of 30% to 50%, and a layered structure in an amount of more than 50% to 70% or less. It may be. As a specific example, the lithium transition metal complex oxide may contain 30% or more, 35% or more, 40% or more, 41% or more, or 42% or more of the spinel structure confirmed by Rietveld analysis, and may also include 50% or more. It may include less than, 49% or less, 48% or less, 47% or less, 46% or less, 45% or less, 44% or less, or 43% or less. In addition, the lithium transition metal complex oxide may contain more than 50%, more than 51%, more than 52%, more than 53%, more than 54%, more than 56%, or more than 57% of the layered structure confirmed by Rietveld analysis. It may also include 70% or less, 65% or less, 60% or less, 59% or less, or 58% or less. Here, the content refers to the ratio between the spinel structure and the layered structure confirmed by Rietveld analysis, and as a specific example, it may be the intensity ratio between the peak intensities for each structure confirmed in XRD data.

According to one embodiment of the present invention, the spinel-structured lithium transition metal complex oxide may have an average composition represented by the following Chemical Formula 1.

[Formula 1]

LiNi _a Mn _b O ₄

In Formula 1, 0.4<a<0.6, 1.4<b<1.6, a+b=2.

According to one embodiment of the present invention, a may be the molar ratio of nickel (Ni), and may be greater than 0.4, greater than 0.41, greater than 0.42, greater than 0.43, greater than 0.44, or greater than 0.45, and may be less than 0.6, 0.59 or greater. It may be less than or equal to 0.58, less than or equal to 0.57, less than or equal to 0.56, or less than or equal to 0.55.

According to one embodiment of the present invention, b may be the molar ratio of manganese (Mn), and may be greater than 1.4, greater than 1.41, greater than 1.42, greater than 1.43, greater than 1.44, or greater than 1.45, and also less than 1.6, 1.59 or greater. It may be 1.58 or less, 1.57 or less, 1.56 or less, or 1.55 or less.

According to one embodiment of the present invention, the layered structure of the lithium transition metal complex oxide may have an average composition represented by the following formula (2).

[Formula 2]

_{LixNiyMnzO2 _ _ _}

In Formula 2, 1.1<x<1.3, 0.1<y<0.3, 0.5<z<0.7, x+y+z=2.

According to one embodiment of the present invention, x may be the molar ratio of lithium (Li), and may be greater than 1.1, greater than 1.11, greater than 1.12, greater than 1.13, greater than 1.14, or greater than 1.15, and also less than 1.3, 1.29 or greater. It may be 1.28 or less, 1.27 or less, 1.26 or less, or 1.25 or less.

According to one embodiment of the present invention, y may be the molar ratio of nickel (Ni), and may be greater than 0.1, greater than 0.11, greater than 0.12, greater than 0.13, greater than 0.14, or greater than 0.15, and may be less than 0.3, 0.29 or greater. It may be 0.28 or less, 0.27 or less, 0.26 or less, or 0.25 or less.

According to one embodiment of the present invention, z may be the molar ratio of manganese (Mn), and may be greater than 0.5, greater than 0.51, greater than 0.52, greater than 0.53, greater than 0.54, or greater than 0.55, and also less than 0.7, 0.69. It may be less than or equal to 0.68, less than or equal to 0.67, less than or equal to 0.66, or less than or equal to 0.65.

According to one embodiment of the present invention, the lithium transition metal complex oxide may have an average composition represented by the following formula (3) measured by ICP. Here, the average composition measured by ICP means the average composition of the positive electrode active material itself, including both spinel structure and layered structure, measured by ICP.

[Formula 3]

Li _m Ni _n M n _o O ₂

In Formula 3, 1.12<m<1.14, 0.300<n<0.320, 0.545<o<0.570, 1.98<m+n+o<2.02.

According to one embodiment of the present invention, m may be the molar ratio of lithium (Li), and may be greater than 1.12, greater than 1.121, greater than 1.122, greater than 1.123, greater than 1.124, or greater than 1.125, and also less than 1.14, 1.139. It may be 1.138 or less, 1.137 or less, 1.136 or less, or 1.135 or less.

According to one embodiment of the present invention, n may be the molar ratio of nickel (Ni), and is greater than 0.300, greater than 0.301, greater than 0.302, greater than 0.303, greater than 0.304, greater than 0.305, greater than 0.306, greater than 0.307, greater than 0.308, Or it may be 0.310 or more, and may also be less than 0.320, 0.319 or less, 0.318 or less, 0.317 or less, or 0.316 or less.

According to one embodiment of the present invention, o may be the molar ratio of manganese (Mn), and may be greater than 0.545, 0.546 or greater, 0.547 or greater, 0.548 or greater, 0.549 or greater, or 0.550 or greater, and may also be less than 0.570, 0.569 or greater. It may be 0.568 or less, 0.567 or less, 0.566 or less, 0.565 or less, 0.564 or less, 0.563 or less, 0.562 or less, 0.561 or less, or 0.560 or less.

According to one embodiment of the present invention, the average particle diameter of the primary particles may be 1 ㎛ or more. The average particle diameter (D ₅₀ ) of the primary particles may be measured using a particle size analysis (PSA), and may be the middle value of the Gaussian curve in a graph of the Gaussian function of the measured particle size. Additionally, the average particle diameter of the primary particles may be the number average particle diameter of the primary particles confirmed by SEM. As a specific example, the average particle diameter of the primary particles may be 1 ㎛ or more, 10 ㎛ or less, 9 ㎛ or less, 8 ㎛ or less, 7 ㎛ or less, 6 ㎛ or less, or 5 ㎛ or less.

According to one embodiment of the present invention, the lithium transition metal complex oxide may not contain expensive cobalt, and may improve the initial efficiency and stability of the lithium secondary battery without containing cobalt.

Cathode active material manufacturing method

The present invention provides a method for manufacturing a positive electrode active material. The method of manufacturing the positive electrode active material includes a lithium transition metal composite oxide containing lithium, nickel, and manganese, and the lithium transition metal composite oxide includes both a spinel structure and a layered structure, but the layered structure is contained in excess compared to the spinel structure. It may be a method for producing a positive electrode active material in which the average primary particle diameter is 1 ㎛ or more.

According to one embodiment of the present invention, the method for producing a positive electrode active material is to prepare a synthetic solution by mixing a lithium raw material and a transition metal precursor including a nickel precursor and a manganese precursor in an aqueous solvent at a temperature of 25°C or more and 100°C or less. forming step (S10); And it may include a step (S20) of drying and calcining the synthetic solution formed in step (S10).

According to one embodiment of the present invention, the step (S10) is a step for producing a precursor for simultaneously forming a spinel structure and a layered structure in forming a complex oxide of transition metals containing lithium, nickel, and manganese. It can be. The step (S10) is performed by mixing a lithium raw material and a transition metal precursor including a nickel precursor and a manganese precursor, thereby separately introducing a spinel structure into the lithium transition metal complex oxide. NiMn(OH) ₂ is deposited by a precipitation method. The process can be simplified because there is no need to form a transition metal precursor, add an additional manganese precursor, add an expensive cobalt precursor during precursor synthesis, or introduce an additional spinel structure. In addition, when manufacturing a precursor for simultaneously forming a spinel structure and a layered structure according to the step (S10), since the precipitation method according to coprecipitation is not performed, the average particle diameter of the primary particles of the positive electrode active material is 1 ㎛ or more. It can be increased.

According to one embodiment of the present invention, the lithium raw material may be a lithium raw material that can be used in manufacturing a positive electrode active material, for example, lithium hydroxide, lithium carbonate, etc., but in terms of the purpose of the present invention, It may be preferable to use lithium acetate, and the lithium acetate may be lithium acetate dihydrate.

According to one embodiment of the present invention, the nickel precursor may be a nickel precursor that can be used in manufacturing a positive electrode active material precursor, for example, nickel sulfate, nitrate, etc., but from the perspective of the purpose of the present invention, nickel precursor may be used as is. It may be preferable to use acetate, and the nickel acetate may be nickel acetate tetrahydrate.

According to one embodiment of the present invention, the manganese precursor may be a manganese precursor that can be used in manufacturing a positive electrode active material precursor, for example, manganese sulfate, nitrate, etc., but from the perspective of the purpose of the present invention, manganese precursor It may be preferable to use acetate, and the manganese acetate may be manganese acetate tetrahydrate.

According to one embodiment of the present invention, the aqueous solvent may be ion-exchanged water.

According to one embodiment of the present invention, the mixing temperature in the step (S10) may be 25 ℃ or higher and 100 ℃ or lower, and specific examples include 25 ℃ or higher, 30 ℃ or higher, 35 ℃ or higher, 40 ℃ or higher, 45 ℃ or higher, It may be 50°C or higher, 55°C or higher, 60°C or higher, 65°C or higher, 70°C or higher, 75°C or higher, or 80°C or higher, and may also be 100°C or lower, 95°C or lower, 90°C or lower, 85°C or lower, or It may be below 80°C.

According to one embodiment of the present invention, the (S20) step may be a step of drying and calcining the synthesis solution to obtain a positive electrode active material in the form of a lithium transition metal complex oxide from the synthesis solution formed in the (S10) step. .

According to one embodiment of the present invention, the drying in the step (S20) may be performed to obtain a precursor for simultaneously forming a spinel structure and a layered structure by removing the solvent in the synthesis solution, and as a specific example, spray drying It may be implemented. In this way, when the drying in the step (S20) is carried out by spray drying, the precursor is obtained in the form of a spherical powder, which is advantageous for handling, and there is no need to perform a separate pulverization step as with the gel-type precursor.

According to one embodiment of the present invention, during the spray drying, the inlet temperature of the spray drying device may be adjusted to 100 ℃ or more and 200 ℃ or less, and specific examples include 100 ℃ or more, 110 ℃ or more, 120 ℃ or more, 130 ℃ or more. , 140 ℃ or higher, or 150 ℃ or higher, and may also be 200 ℃ or lower, 190 ℃ or lower, 180 ℃ or lower, 170 ℃ or lower, 160 ℃ or lower, or 150 ℃ or lower, and within this range, the precursor with a high degree of spheroidization can be obtained.

According to one embodiment of the present invention, the calcination in the step (S20) is a step for obtaining a positive electrode active material in the form of a lithium transition metal complex oxide by oxidizing the precursor powder obtained by the drying, at a temperature of 450°C or more and 1,000°C. It can be carried out at temperatures below.

According to one embodiment of the present invention, the firing is performed at 450°C or higher, 500°C or higher, 550°C or higher, 600°C or higher, 650°C or higher, 700°C or higher, 750°C or higher, 800°C or higher, 850°C or higher, and 900°C. It may be carried out at a temperature of 950°C or higher, and may also be carried out at a temperature of 1,000°C or lower, 950°C or lower, or 900°C or lower. In addition, the firing may be carried out in a plurality of stages, such as primary firing and secondary firing, and at this time, the secondary firing may be carried out at a higher temperature than the primary firing. As a more specific example, the firing may be divided into primary firing at a temperature of 450°C or higher and 600°C or lower, and secondary firing at a temperature of 800°C or higher and 1,000°C or lower.

According to one embodiment of the present invention, the firing may be carried out for 1 hour or more and 24 hours or less, and as a specific example, may be carried out for 1 hour or more, 2 hours or more, 3 hours or more, 4 hours or more, or 5 hours or more. It can also be carried out for 24 hours or less, 22 hours or less, 20 hours or less, 18 hours or less, 16 hours or less, 14 hours or less, or 12 hours or less. Additionally, when the firing is divided into a plurality of stages, such as primary firing and secondary firing, the secondary firing may be carried out for a longer time than the primary firing. As a more specific example, the firing may be divided into primary firing for a period of time between 1 hour and 10 hours and secondary firing for a period of between 8 hours and 24 hours.

According to one embodiment of the present invention, as described above, the method for producing the positive electrode active material is a one pot synthesis in which a lithium raw material and a transition metal precursor are mixed in step (S10) to form a synthesis solution. It may be carried out, and accordingly, while the size of the primary particle is 1 ㎛ or more, the spinel structure is inserted into the layered structure, and the initial efficiency and stability of the lithium secondary battery containing it can be improved.

According to one embodiment of the present invention, the positive electrode active material manufactured according to the positive electrode active material manufacturing method includes a lithium transition metal complex oxide containing lithium, nickel, and manganese, and the lithium transition metal complex oxide has a spinel structure and a layered structure. It may include both structures at the same time. Here, the spinel structure can be formed by adjusting the ratio of the lithium raw material mixed in step (S10) and the transition metal precursor including a nickel precursor and a manganese precursor. That is, the spinel structure may be determined depending on the composition of the transition metal precursor including lithium raw material, nickel precursor, and manganese precursor during precursor synthesis. As a specific example, when mixing in step (S10), if the proportion of lithium raw material is small, a spinel structure is formed during firing in step (S20). However, if the ratio of the lithium raw material is excessively reduced, the ratio of the spinel structure increases, and if the ratio of the lithium raw material is excessively increased, the spinel structure is not formed. Therefore, in order to form a lithium transition metal complex oxide containing both a spinel structure and a layered structure, but containing an excessive amount of the layered structure compared to the spinel structure, it is necessary to appropriately adjust the ratio of the lithium raw material when mixing in step (S10). there is.

According to one embodiment of the present invention, the molar ratio between the lithium raw material introduced in the step (S10) and the transition metal precursor including the nickel precursor and the manganese precursor is the average composition measured by ICP represented by Formula 3 above. It may be the same as the molar ratio. As a specific example, the molar ratio of the lithium raw material may be greater than 1.12, greater than 1.121, greater than 1.122, greater than 1.123, greater than 1.124, or greater than 1.125, and may also be less than 1.14, less than 1.139, less than 1.138, less than 1.137, less than 1.136, Or it may be 1.135 or less, and the molar ratio of the nickel precursor may be greater than 0.300, 0.301 or greater, 0.302 or greater, 0.303 or greater, 0.304 or greater, 0.305 or greater, 0.306 or greater, 0.307 or greater, 0.308 or greater, or 0.310 or greater, and may be 0.320 or greater. may be less than 0.319, 0.318 or less, 0.317 or less, or 0.316 or less, and the molar ratio of the manganese precursor may be greater than 0.545, 0.546 or more, 0.547 or more, 0.548 or more, 0.549 or more, or 0.550 or more, and may also be less than 0.570, It may be 0.569 or less, 0.568 or less, 0.567 or less, 0.566 or less, 0.565 or less, 0.564 or less, 0.563 or less, 0.562 or less, 0.561 or less, or 0.560 or less.

According to one embodiment of the present invention, as described above, the spinel structure and the layered structure may be synthesized simultaneously, and specifically, the precursor formed in the (S10) step is dried in the (S20) step. and baking.

anode

The present invention provides a positive electrode containing the above positive electrode active material.

According to one embodiment of the present invention, the positive electrode may include a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and the positive electrode active material layer may include the positive electrode active material.

According to one embodiment of the present invention, the positive electrode current collector may include a highly conductive metal, and the positive electrode active material layer is easily adhered, but is not particularly limited as long as it is not reactive within the voltage range of the battery. The positive electrode current collector may be, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or an aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. Additionally, the positive electrode current collector may typically have a thickness of 3 ㎛ to 500 ㎛, and fine irregularities may be formed on the surface of the current collector to increase the adhesion of the positive electrode active material. For example, it can be used in various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven materials.

According to one embodiment of the present invention, the positive electrode active material layer may optionally include a conductive material and a binder along with the positive electrode active material. At this time, the positive electrode active material may be included in an amount of 80% to 99% by weight, more specifically 85% to 98.5% by weight, based on the total weight of the positive electrode active material layer, and can exhibit excellent capacity characteristics within this range. there is.

According to one embodiment of the present invention, the conductive material is used to provide conductivity to the electrode, and can be used without particular limitation as long as it does not cause chemical change and has electronic conductivity in the battery being constructed. Specific examples include graphite such as natural graphite and artificial graphite; Carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; Metal powders or metal fibers such as copper, nickel, aluminum, and silver; Conductive tubes such as carbon nanotubes; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Or conductive polymers such as polyphenylene derivatives, etc., of which one type alone or a mixture of two or more types may be used. The conductive material may be included in an amount of 0.1% to 15% by weight based on the total weight of the positive electrode active material layer.

According to one embodiment of the present invention, the binder serves to improve adhesion between positive electrode active material particles and adhesion between the positive active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylalcohol, polyacrylonitrile, and polymethylmethane. Crylate (polymethymethaxrylate), carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene- Diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, polyacrylic acid, and polymers whose hydrogens are substituted with Li, Na, or Ca, or various copolymers thereof Combinations, etc. may be mentioned, and one type of these may be used alone or a mixture of two or more types may be used. The binder may be included in an amount of 0.1% by weight to 15% by weight based on the total weight of the positive electrode active material layer.

According to one embodiment of the present invention, the positive electrode can be manufactured according to a conventional positive electrode manufacturing method except for using the positive electrode active material described above. Specifically, the positive electrode is prepared by dissolving or dispersing the positive electrode active material and optionally a binder, a conductive material, and a dispersant in a solvent, and the composition for forming a positive active material layer is applied to the positive electrode current collector and then dried. and rolling, or by casting the composition for forming the positive electrode active material layer on a separate support and then peeling from this support and laminating the film obtained on the positive electrode current collector.

According to one embodiment of the present invention, the solvent may be a solvent commonly used in the art, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, and N-methylpyrrolidone. (NMP), dimethylformamide (DMF), acetone, or water, among which one type alone or a mixture of two or more types may be used. The amount of the solvent used is to dissolve or disperse the positive electrode active material, conductive material, binder, and dispersant in consideration of the application thickness and manufacturing yield of the slurry, and to have a viscosity capable of exhibiting excellent thickness uniformity when applied for subsequent positive electrode production. That's enough.

Lithium secondary battery

The present invention provides a lithium secondary battery including the positive electrode.

According to one embodiment of the present invention, the lithium secondary battery includes the positive electrode; cathode; It may include a separator and an electrolyte interposed between the anode and the cathode. Additionally, the lithium secondary battery may optionally further include a battery container that accommodates the electrode assembly of the positive electrode, negative electrode, and separator, and a sealing member that seals the battery container.

According to one embodiment of the present invention, the negative electrode may include a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

According to one embodiment of the present invention, the negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, for example, copper, stainless steel, aluminum, nickel, titanium, plastic. Surface treatment of carbon, copper or stainless steel with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector may typically have a thickness of 3 ㎛ to 500 ㎛, and like the positive electrode current collector, fine irregularities may be formed on the surface of the current collector to strengthen the bonding force of the negative electrode active material. For example, it can be used in various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven materials.

According to one embodiment of the present invention, the negative electrode active material layer may optionally include a binder and a conductive material along with the negative electrode active material.

According to one embodiment of the present invention, a compound capable of reversible intercalation and deintercalation of lithium may be used as the negative electrode active material. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; Metallic compounds that can be alloyed with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; Metal oxides that can dope and undope lithium, such as SiOβ (0<β<2), SnO ₂ , vanadium oxide, and lithium vanadium oxide; Alternatively, a composite containing the above-described metallic compound and a carbonaceous material, such as a Si-C composite or Sn-C composite, may be used, and any one or a mixture of two or more of these may be used. Additionally, a metallic lithium thin film may be used as the negative electrode active material. Additionally, the carbon material may include both low-crystalline carbon and high-crystalline carbon. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and high-crystalline carbon includes amorphous, plate-shaped, flaky, spherical, or fibrous natural graphite, artificial graphite, and Kish graphite. graphite, pyrolytic carbon, mesophase pitch based carbonfiber, meso-carbon microbeads, mesophase pitches, and petroleum or coal tar pitch derived High-temperature calcined carbon such as cokes is a representative example. The negative electrode active material may be included in an amount of 80% to 99% by weight based on the total weight of the negative electrode active material layer.

According to one embodiment of the present invention, the binder of the negative electrode active material layer is a component that assists in bonding between the conductive material, the active material, and the current collector, and is typically contained in the amount of 0.1% by weight to 10% by weight based on the total weight of the negative electrode active material layer. is added. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, and polytetra. Examples include fluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluorine rubber, and various copolymers thereof.

According to one embodiment of the present invention, the conductive material of the negative electrode active material layer is a component to further improve the conductivity of the negative electrode active material, and is contained in an amount of 10% by weight or less, preferably 5% by weight or less, based on the total weight of the negative electrode active material layer. may be added. These conductive materials are not particularly limited as long as they have conductivity without causing chemical changes in the battery, and examples include graphite such as natural graphite or artificial graphite; Carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; Conductive fibers such as carbon fiber and metal fiber; fluorinated carbon; Metal powders such as aluminum and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

According to one embodiment of the present invention, the negative electrode is manufactured by applying and drying a composition for forming a negative electrode active material layer prepared by dissolving or dispersing the negative electrode active material and optionally the binder and the conductive material in a solvent on the negative electrode current collector, or Alternatively, it can be manufactured by casting the composition for forming the negative electrode active material layer on a separate support and then peeling off the support and laminating the film obtained on the negative electrode current collector.

According to one embodiment of the present invention, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. It can be used without particular restrictions as long as it is normally used as a separator in a lithium secondary battery, and in particular, it can be used for ion movement in the electrolyte. It is desirable to have low resistance and excellent electrolyte moisturizing ability. Specifically, porous polymer films, for example, porous polymer films made of polyolefin polymers such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer, or these. A laminated structure of two or more layers may be used. In addition, conventional porous nonwoven fabrics, for example, nonwoven fabrics made of high melting point glass fibers, polyethylene terephthalate fibers, etc., may be used. Additionally, a coated separator containing ceramic components or polymer materials may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

According to an embodiment of the present invention, the electrolyte may include an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, and a molten inorganic electrolyte that can be used when manufacturing a lithium secondary battery. It is not limited to these. As a specific example, the electrolyte may include an organic solvent and a lithium salt.

According to one embodiment of the present invention, the organic solvent may be used without particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent includes ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; Ether-based solvents such as dibutyl ether or tetrahydrofuran; Ketone-based solvents such as cyclohexanone; Aromatic hydrocarbon solvents such as benzene and fluorobenzene; Dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC) ), carbonate-based solvents such as; Alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (R is a straight-chain, branched or ring-structured hydrocarbon group having 2 to 20 carbon atoms and may include a double bond aromatic ring or ether bond); Amides such as dimethylformamide; Dioxolanes such as 1,3-dioxolane; Alternatively, sulfolane, etc. may be used. Among these, carbonate-based solvents are preferable, and cyclic carbonates (e.g., ethylene carbonate or propylene carbonate, etc.) with high ionic conductivity and high dielectric constant that can improve the charging and discharging performance of the battery, and low-viscosity linear carbonate-based compounds ( For example, ethylmethyl carbonate, dimethyl carbonate, diethyl carbonate, etc.) are more preferable.

According to one embodiment of the present invention, the lithium salt can be used without particular limitation as long as it is a compound that can provide lithium ions used in lithium secondary batteries. Specifically, the anions of the lithium salt include F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , N(CN) ₂ ^- , BF ₄ ^- , CF ₃ CF ₂ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , (FSO ₂ ) ₂ N ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , (CF ₃ SO ₂ ) ₃ C ^- , CF ₃ (CF ₂ ) ₇ SO ₃ ^- , CF ₃ CO ₂ ^- , CH ₃ CO ₂ ^- , SCN ^- , and (CF ₃ CF ₂ SO ₂ ) ₂ N ^- It may be at least one selected from the group consisting of, The lithium salt is LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAl0 ₄ , LiAlCl ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN(C ₂ F ₅ SO ₃ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) ₂ , LiCl, LiI, or LiB(C ₂ O ₄ ) ₂ may be used. The concentration of the lithium salt is preferably used within the range of 0.1 M to 2.0 M. When the concentration of lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity, so excellent electrolyte performance can be achieved and lithium ions can move effectively.

According to one embodiment of the present invention, in addition to the electrolyte components, the electrolyte contains halo such as difluoroethylene carbonate for the purpose of improving battery life characteristics, suppressing battery capacity reduction, and improving battery discharge capacity. Alkylene carbonate compounds, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexanoic acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazoli One or more additives such as dinon, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxy ethanol, or aluminum trichloride may be further included. At this time, the additive may be included in an amount of 0.1% to 5% by weight based on the total weight of the electrolyte.

Since the lithium secondary battery containing the positive electrode active material according to the present invention stably exhibits excellent capacity characteristics, output characteristics, and lifespan characteristics, it is used in portable devices such as mobile phones, laptop computers, and digital cameras, and hybrid electric vehicles. It is useful in the field of electric vehicles such as HEV) and electric vehicles (EV).

The external shape of the lithium secondary battery of the present invention is not particularly limited, but may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.

The lithium secondary battery according to the present invention can not only be used in battery cells used as a power source for small devices, but can also be preferably used as a unit cell in medium to large-sized battery modules containing multiple battery cells.

Accordingly, according to one embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

According to one embodiment of the present invention, the battery module or battery pack includes a power tool; Electric vehicles, including electric vehicles (EV), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEV); Alternatively, it can be used as a power source for any one or more mid- to large-sized devices among power storage systems.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement it. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein.

Example

Example 1

Lithium acetate dihydrate (CH ₃ COOLi.2H ₂ O), nickel acetate tetrahydrate (Ni(CH3COO) _{2.4H 2} O) and manganese acetate tetrahydrate ( _Mn (CH3COO) 2.4H ₂ O) were prepared by lithium:nickel: Manganese was added to ion-exchanged water so that the molar ratio was 1.13:0.316:0.550, and a synthetic solution was formed while stirring at a temperature of 80°C. At this time, lithium volatilizes during firing, so when forming the synthetic solution, lithium was added in an excessive amount of 0.05 molar ratio based on the molar ratio of the transition metal to 1 to maintain the molar ratio between lithium and the transition metal. After stirring was sufficiently completed, spray drying was performed at an inlet temperature of 150°C of the spray drying device, and a dried product was obtained. The dried product obtained above was heated at 450°C for 5 days. A positive electrode active material was manufactured by performing primary firing for 12 hours, followed by secondary firing at 900°C for 12 hours.

Example 2

A positive electrode active material was manufactured in the same manner as in Example 1, except that the secondary calcination was performed at 950° C. for 12 hours.

Comparative Example 1

In Example 1, lithium acetate dihydrate (CH ₃ COOLi.2H ₂ O), nickel acetate tetrahydrate (Ni(CH3COO) _{2.4H 2} O), and manganese acetate tetrahydrate (Mn(CH3COO) _{2.4H 2} O) ) was added to ion-exchanged water so that the molar ratio of lithium:nickel:manganese was 1.17:0.283:0.543, and a positive electrode active material was prepared in the same manner as in Example 1.

Comparative Example 2

In Example 1, lithium acetate dihydrate (CH ₃ COOLi.2H ₂ O), nickel acetate tetrahydrate (Ni(CH3COO) _{2.4H 2} O), and manganese acetate tetrahydrate (Mn(CH3COO) _{2.4H 2} O) ) was added to ion-exchanged water so that the molar ratio of lithium:nickel:manganese was 1.13:0.298:0.571, and a positive electrode active material was prepared in the same manner as in Example 1.

Experiment example

Experimental Example 1: Primary particle size analysis

The positive electrode active material prepared in Example 1 was photographed at 5 kV using a back scattered method using a scanning electron microscope (SEM), and is shown in FIG. 1.

As can be seen from Figure 1, the positive electrode active material manufactured according to the present invention was confirmed to have a primary particle size of 1 ㎛ or more.

Experimental Example 2: XRD analysis

For each positive electrode active material prepared in the above examples and comparative examples, after XRD measurement, each XRD data is shown in FIG. 2.

At this time, the XRD was performed by collecting 2 g to 3 g of positive electrode active material particles from each positive active material powder prepared in the examples and comparative examples, and using Cu-Kα line (wavelength 1.54 Å) at an acceleration voltage of 40 kV/40. Measurements were made using X-ray diffraction analysis in a 2θ range of 15° to 90° at a scan rate of 0.2°/sec at mA.

In addition, through Rietveld analysis using BRUKER's TOPAS software on the shown in

Data measured by XRD are relative values and may vary depending on the measuring device and conditions, but the ratio between peak intensities is an absolute value and does not change depending on the measuring device and conditions.

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Spinel structure content (%) 42.87 42.87 - 53.05 Layered structure content (%) 57.13 57.13 100.00 46.95

As shown in Table 1, the positive electrode active materials of Examples 1 and 2 prepared according to the present invention not only formed a spinel structure and a layered structure simultaneously, but also formed a spinel structure by controlling the ratio of lithium raw materials when forming the synthetic solution. It was confirmed that it contained an excessive amount of contrast layered structure. In addition, in Examples 1 and 2, although there was a difference in temperature during the secondary calcination, it was confirmed that the contents of the spinel structure and the layered structure were the same because the precursor was manufactured in the same way by including lithium raw materials in the same ratio. there was.

On the other hand, in the case of Comparative Example 1, it was confirmed that the ratio of lithium raw material was excessively higher than that of Examples 1 and 2, so that no spinel structure was formed at all.

In addition, in the case of Comparative Example 2, the ratio of lithium raw material was lower than that of Examples 1 and 2, so it was confirmed that the spinel structure was formed in excess of the layered structure.

Experimental Example 3: ICP analysis

After taking 0.1 g of each positive electrode active material prepared in the above Examples and Comparative Examples, 1.5 ml of 0.1 M hydrochloric acid was added and heated to 80° C. to dissolve the positive electrode active material. Afterwards, a small amount of hydrogen peroxide was added to completely dissolve the positive electrode active material to prepare a solution. Subsequently, the solution was diluted with ion-exchanged water so that the total volume was 30 ml, and this was diluted again 10 times to prepare an analysis sample. Using an ICP device, the ratio of constituent elements present in the analysis sample was measured, and the ratios of elements of lithium, nickel, and manganese are shown in Table 2 below.

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Li 1.13 1.13 1.17 1.13 Ni 0.316 0.316 0.283 0.298 Mn 0.550 0.550 0.543 0.571

As shown in Table 2, as a result of ICP analysis, it was confirmed that a positive electrode active material, which is a lithium transition metal complex oxide, was prepared according to a controlled molar ratio when forming a synthetic solution according to Examples and Comparative Examples.

Experimental Example 4: Coin-type half-cell manufacturing and capacity characteristic evaluation

92.5% by weight of the positive electrode active material prepared in the above examples and comparative examples, 3.0% by weight of Super P as a conductive material, and 4.5% by weight of polyvinylidene fluoride (PVDF) as a binder were mixed in N-methylpyrrolidone (NMP) solvent. A positive electrode slurry was prepared. The prepared positive electrode slurry was applied to one side of an aluminum current collector, dried at 130°C, and rolled to prepare a positive electrode.

An electrode assembly was manufactured using a lithium metal electrode as a negative electrode and a porous polyethylene separator between the positive and negative electrodes. Place it inside the battery case and inject an electrolyte solution in which 1 M LiPF ₆ is dissolved in an organic solvent mixed with ethylene carbonate (EC): ethyl methyl carbonate (EMC): diethyl carbonate (DEC) in a volume ratio of 3:4:3. A coin-type half cell was manufactured.

Using the coin-type half-cell containing the positive electrode active material of the examples and comparative examples prepared above, charging to 4.65 V at 0.1 C constant current at 45 ° C, and then discharging to 2.0 V at 0.1 C, performed an activation process (formation). This was carried out, and the charging and discharging capacities at this time were measured.

Subsequently, the battery was charged to 4.4 V at 0.1 C constant current at 25°C, and then discharged to 2.5 V at 0.1 C to measure the initial charge and discharge capacity.

Subsequently, after charging to 4.4 V at 0.33 C constant current at 25 ° C, one cycle of discharging to 2.5 V at 0.33 C was repeated for a total of 50 cycles of charging and discharging, and after measuring the charging and discharging capacity, The capacity maintenance rate was measured compared to the initial charge and discharge capacity.

The charging and discharging capacity and capacity maintenance rate measured at each stage are shown in Table 3 below.

division activation process Initial charge and discharge Capacity maintenance rate
(%) charging capacity
(mAh/g) discharge capacity
(mAh/g) efficiency
(%) charging capacity
(mAh/g) discharge capacity
(mAh/g) efficiency
(%) Example 1 267.87 214.85 80.21 175.5 168.17 95.82 96.08 Example 2 291.92 241.71 82.80 189.47 168.11 88.73 96.08 Comparative Example 1 279.81 207.69 74.23 167.78 150.96 89.97 95.73 Comparative Example 2 242.53 179.87 74.17 126.25 121.72 96.41 92.11

As shown in Table 3, in the positive electrode active materials of Examples 1 and 2 prepared according to the present invention, the lithium transition metal oxide contains both a spinel structure and a layered structure, but contains an excessive amount of the layered structure compared to the spinel structure, Since the average particle diameter of the primary particles was 1 ㎛ or more, it was confirmed that the charge and discharge capacity and efficiency during the activation process were reduced, as well as the decrease in capacity during the initial charge and discharge after activation, while the efficiency was excellent and the capacity maintenance rate was also excellent. .

On the other hand, in the positive electrode active material of Comparative Example 1, since the lithium transition metal oxide does not contain a spinel structure, the discharge capacity rapidly decreases during the activation process, resulting in a decrease in efficiency, and the capacity rapidly decreases during the initial charge and discharge after activation. I was able to confirm that it was done.

In addition, the positive electrode active material of Comparative Example 2 cannot secure sufficient charge and discharge capacity according to the layered structure because the lithium transition metal oxide contains an excessive amount of spinel structure, resulting in initial charge and discharge not only during the activation process but also after activation. In all cases, it was confirmed that the capacity was significantly reduced and the capacity maintenance rate was poor.

From these results, the positive electrode active material of the present invention is manufactured through a single process synthesis, and the size of the primary particle is 1 ㎛ or more, and the spinel structure is inserted into the layered structure, improving the initial efficiency and stability of the lithium secondary battery containing it. It was confirmed that improvements could be made.

Claims (15)

Contains a lithium transition metal complex oxide containing lithium, nickel, and manganese,
The lithium transition metal complex oxide includes both a spinel structure and a layered structure, but contains an excess of the layered structure compared to the spinel structure,
A positive electrode active material with an average primary particle diameter of 1 ㎛ or more. According to paragraph 1,
The positive electrode active material is a secondary particle in which a plurality of primary particles are aggregated. According to paragraph 1,
The lithium transition metal complex oxide is a positive electrode active material containing a spinel structure confirmed by Rietveld analysis in an amount of 30% to 50% and a layered structure in an amount of more than 50% to 70% or less. According to paragraph 1,
The positive electrode active material in which the spinel-structured lithium transition metal complex oxide has an average composition represented by the following Chemical Formula 1:
[Formula 1]
LiNi _a Mn _b O ₄
In Formula 1, 0.4<a<0.6, 1.4<b<1.6, a+b=2. According to paragraph 1,
The layered structure of the lithium transition metal composite oxide is a positive electrode active material having an average composition represented by the following formula (2):
[Formula 2]
_{LixNiyMnzO2 _ _ _}
In Formula 2, 1.1<x<1.3, 0.1<y<0.3, 0.5<z<0.7, x+y+z=2. According to paragraph 1,
The lithium transition metal complex oxide is a positive electrode active material having an average composition represented by the following formula 3 as measured by ICP:
[Formula 3]
Li _m Ni _n M n _o O ₂
In Formula 3, 1.12<m<1.14, 0.300<n<0.320, 0.545<o<0.570, 1.98<m+n+o<2.02. According to paragraph 1,
A positive electrode active material in which the lithium transition metal complex oxide does not contain cobalt. Forming a synthetic solution by mixing a lithium raw material and a transition metal precursor including a nickel precursor and a manganese precursor in an aqueous solvent at a temperature of 25°C or more and 100°C or less (S10); and
A method of producing a positive electrode active material including the step (S20) of drying and calcining the synthetic solution formed in step (S10). According to clause 8,
A method of manufacturing a positive electrode active material in which the drying in step (S20) is carried out by spray drying. According to clause 9,
A method of producing a positive electrode active material, wherein during the spray drying, the inlet temperature of the spray drying device is 100°C or more and 200°C or less. According to clause 8,
A method for producing a positive electrode active material, wherein the firing in the step (S20) is performed at a temperature of 450 ℃ or more and 1,000 ℃ or less. According to clause 8,
The method of manufacturing a positive electrode active material is carried out through one pot synthesis. According to clause 8,
The positive electrode active material manufactured according to the above positive electrode active material manufacturing method includes lithium, lithium transition metal complex oxide containing nickel, and manganese,
The lithium transition metal complex oxide includes both a spinel structure and a layered structure, but contains an excess of the layered structure compared to the spinel structure,
A method of manufacturing a positive electrode active material in which the spinel structure and the layered structure are synthesized simultaneously. A positive electrode comprising the positive electrode active material according to any one of claims 1 to 7. A lithium secondary battery comprising the positive electrode according to claim 14.