WO2020235893A1 - Cathode active material having 5v-grade spinel structure, and preparation method therefor - Google Patents

Abstract

The present invention relates to a cathode active material having a 5V-grade spinel structure, the material being represented by <chemical formula 1> below, wherein, in <chemical formula 1>, the oxidation number of Mn includes +3 and +4; x>0, y>0, 0<β<4, and 0<α<0.03, M1 is a transition metal of which the oxidation number is +5 or +6, M2 is an element of which the oxidation number is -1, the average oxidation number of Mn is from 3.5 to less than 4, the average oxidation number of Mn decreases according to an increase in an α value or a β value, and x+y=2. <Chemical formula 1> LiNi_xMn_y-αM1_αO_4-βM2_β

Description

5V class spinel structure cathode active material, and its manufacturing method

The present application relates to a positive electrode active material and a method of manufacturing the same, and more particularly, to a positive electrode active material having a 5V class spinel structure having a metal ion mixed with an oxidizing number, and a method of manufacturing the same.

With the development of portable mobile electronic devices such as smartphones, MP3 players, and tablet PCs, the demand for secondary batteries capable of storing electrical energy is exploding. In particular, with the advent of electric vehicles, medium and large-sized energy storage systems, and portable devices requiring high energy density, demand for lithium secondary batteries is increasing.

As the demand for lithium secondary batteries increases, research and development on positive electrode active materials used in lithium secondary batteries are in progress. For example, Korean Patent Laid-Open Publication No. 10-2014-0119621 (application number 10-2013-0150315) uses a precursor for manufacturing an excess lithium cathode active material, controls the type and composition of the metal substituted in the precursor, and the type of metal added. And by controlling the amount of addition, a secondary battery having a high voltage capacity and long life characteristics is disclosed.

One technical problem to be solved by the present application is to provide a high-capacity positive electrode active material, a method of manufacturing the same, and a lithium secondary battery including the same.

Another technical problem to be solved by the present application is to provide a cathode active material having a long life, a method of manufacturing the same, and a lithium secondary battery including the same.

Another technical problem to be solved by the present application is to provide a positive electrode active material having high stability, a method of manufacturing the same, and a lithium secondary battery including the same.

Another technical problem to be solved by the present application is to provide a positive electrode active material, a method of manufacturing the same, and a lithium secondary battery including the same, in which life-deterioration characteristics according to the number of charge/discharge are minimized.

The technical problem to be solved by the present application is not limited to the above.

In order to solve the above technical problem, the present application provides a positive electrode active material having a 5V class spinel structure.

In one embodiment, represented by the following <Formula 1>, in the <Formula 1>, the oxidation number of Mn includes +3 and +4, x>0, y>0, 0<β<4 , 0<α<0.03, M1 is a transition metal with an oxidation number of +5 or +6, M2 is an element with an oxidation number of -1, and the average oxidation number of Mn is less than 3.5 to 4, but the average oxidation of Mn The valence decreases as the value of α or β increases, and includes a positive electrode active material having a 5V class spinel structure, which includes x+y=2.

<Formula 1>

LiNi _x Mn _y-α M1 _α O _4-β M2 _β

In one embodiment, 0<α<2, 0<β<2, and Mn is an oxidation number of +3 and +4, relative to the total amount of the oxidation number of +3 Mn is 0.3% to 3.38 It can be %.

In one embodiment, the average oxidation number A of Mn is calculated by the following <Equation 1>, and in <Equation 1>, B may include the oxidation number of M.

<Equation 1>

In an exemplary embodiment, when M1 is a transition metal having an oxidation number of +6, the α value may include a greater influence on the amount of change in the average oxidation number of Mn than the β value.

In an embodiment, in <Formula 1>, 0<α≤0.01 and 0<β≤0.01 may be included.

In an embodiment, in <Formula 1>, M1 may include at least one of Nb, Mo, Ta, and W, and M2 may be F or Cl.

In another aspect of the present invention, embodiments of the present invention include preparing a transition metal aqueous solution containing nickel and manganese, and a doped metal aqueous solution containing M1; Supplying the transition metal aqueous solution, the doping metal aqueous solution, and an ammonia solution to a reactor to prepare a cathode active material precursor doped with the M1 in transition metal hydroxides containing nickel and manganese; And a doping source containing the positive electrode active material precursor, lithium salt, and M2 in a dry manner using a ball mill and firing to prepare a positive electrode active material having a spinel structure doped with the M1 and M2 in nickel, manganese, and lithium oxides. Including the step of, and the step of preparing the doping metal aqueous solution comprises: preparing a sodium hydroxide solution; And dissolving the powder containing M1 in the sodium hydroxide solution, wherein M1 is a transition metal having an oxidation number of +5 or +6, and M2 is an element having an oxidation number of -1. It includes a method of manufacturing a structured positive electrode active material.

According to an embodiment, a cathode active material represented by the following <Chemical Formula 1> is included, but in the following <Chemical Formula 1>, the oxidation number of Mn is +3 or +4, and x>0, y>0, 0 <β<4, 0<α<0.03, M1 is a doped metal different from Ni and Mn, and the average oxidation number of Mn decreases as the β value and the oxidation number of M1 increase, and x+y=2. May include.

<Formula 1>

LiNi _x Mn _y-α M1 _α O _4-β M2 _β

According to an embodiment, more Mn ions having an oxidation number of +4 than Mn ions having an oxidation number of +3 may be included.

According to an embodiment, the average oxidation number A of Mn is calculated by the following <Equation 1>, and in <Equation 1>, B may include the oxidation number of M1.

<Equation 1>

According to an embodiment, in <Formula 1>, x may be 0.5 and y may include 1.5.

According to an embodiment, in <Formula 1>, M is Mo, 0<α≤0.01, and 0<β≤0.01 may be included.

According to an embodiment, in <Formula 1>, M may include at least one of Nb, Mo, Ta, and W.

In order to solve the above technical problem, the present application provides a method of manufacturing a positive electrode active material having a spinel structure.

According to an embodiment, the method of preparing a positive electrode active material having a spinel structure includes preparing a transition metal aqueous solution containing nickel and manganese, and a doping metal aqueous solution containing a doping metal, the transition metal aqueous solution, and the doping metal aqueous solution , And supplying an ammonia solution to a reactor to prepare a positive electrode active material precursor doped with the doping metal in a transition metal hydroxide including nickel and manganese, and a doping source including the positive electrode active material precursor, a lithium salt, and fluorine By mixing and sintering, nickel, manganese, and lithium oxide may include the step of preparing a spinel-structured positive electrode active material doped with the doped metal and fluorine.

According to an embodiment, preparing the doping metal aqueous solution may include preparing a sodium hydroxide solution, and dissolving the powder containing the doped metal in the sodium hydroxide solution.

According to an embodiment, the cathode active material may include those represented by <Chemical Formula 2> below.

<Formula 2>

LiNi _0.5 Mn _1.49 Mo _0.01 O _3.99 F _0.01

According to an embodiment, the concentration of the doped metal and the concentration of fluorine are controlled in the positive electrode active material according to the concentration to which the doping metal aqueous solution is supplied and the mixed concentration of the doping source including fluorine, and In may include controlling the average oxidation number of manganese in the positive electrode active material according to the concentration of the doped metal and the concentration of fluorine.

The positive electrode active material having a 5V class spinel structure according to an embodiment of the present application is represented by the following <Chemical Formula 1>, and in <Chemical Formula 1>, the oxidation number of Mn includes +3 and +4, and x>0, y>0, 0<β<4, 0<α<0.03, M1 is a transition metal with an oxidation number of +5 or +6, M2 is an element with an oxidation number of -1, and the average oxidation number of Mn is from 3.5 to Although less than 4, the average oxidation number of Mn decreases as the α value or β value increases, and may include x+y=2.

Accordingly, a positive electrode active material having a spinel structure with improved charge/discharge characteristics, life characteristics, and thermal stability may be provided.

<Formula 1>

LiN _ix Mn _y-α M1 _α O _4-β M2 _β

1 is a graph measuring the discharge capacity of a secondary battery including a positive electrode active material according to Experimental Examples 1 to 6 and Comparative Example 1 of the present invention.

2 is a graph measuring the discharge capacity according to the number of times of charging and discharging of the secondary battery including the positive electrode active material according to Experimental Examples 1 to 6 and Comparative Example 1 of the present invention.

3 is a graph in which discharge capacity is normalized according to the number of charging and discharging times of a secondary battery including the positive electrode active material according to Experimental Examples 1 to 6 and Comparative Example 1 of the present invention.

4 is a graph showing XPS results of positive electrode active materials according to Experimental Examples 1 to 6 and Comparative Example 1 of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical idea of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed contents may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art.

In the present specification, when a component is referred to as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. In addition, in the drawings, thicknesses of films and regions are exaggerated for effective description of technical content.

In addition, in various embodiments of the present specification, terms such as first, second, and third are used to describe various components, but these components should not be limited by these terms. These terms are only used to distinguish one component from another component. Accordingly, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiment. In addition, in the present specification,'and/or' is used to mean including at least one of the elements listed before and after.

In the specification, expressions in the singular include plural expressions unless the context clearly indicates otherwise. In addition, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, elements, or a combination of the features described in the specification, and one or more other features, numbers, steps, and configurations It is not to be understood as excluding the possibility of the presence or addition of elements or combinations thereof.

Further, in the following description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

A positive electrode active material having a 5V class spinel structure according to an embodiment of the present invention will be described.

The positive electrode active material having a 5V class spinel structure according to an embodiment of the present invention may be represented by the following <Chemical Formula 1>.

<Formula 1>

LiN _ix Mn _y-α M1 _α O _4-β M2 _β

In the <Formula 1>, the oxidation number of Mn includes +3 and +4, and x>0, y>0, 0<β<4, 0<α<0.03, M1 is +5 or + 6 is a transition metal, M2 is an element with an oxidation number of -1, and the average oxidation number of Mn is less than 3.5 to less than 4, but the average oxidation number of Mn decreases as the value of α or β increases, and x+ It may include y=2.

Specifically, in <Formula 1>, 0<α<2, 0<β<2, and more specifically, 0<α≤0.01, and 0<β≤0.01 may be included. In addition, the Mn may include 0.3% to 3.38% of Mn having the oxidation number of +3 relative to the total amount of the oxidation number of +3 and +4. When M1 is a transition metal having an oxidation number of +6, the α value may have a greater influence on a change in the average oxidation number of Mn than the β value.

In <Formula 1>, the oxidation numbers +3 and +4 of Mn ions can be controlled within a predetermined range, and the Mn ions consist only of Mn3+ and Mn4+, which are oxidation numbers +3 and +4, for all Mn ions. Since the Mn ion having an oxidation number of +3 is included in the range of 0.3% to 3.38%, the positive electrode active material of the 5V class spinel structure according to the present embodiment has high structural stability, and thus charging and discharging at a high voltage of 5V is performed. Even so, it is possible to prevent a decrease in initial capacity and a decrease in cycle characteristics. Specifically, if the Mn ion having the oxidation number of +3 is less than 0.3%, the structure of the positive electrode active material may collapse during a 5V charge/discharge cycle, resulting in deterioration of life characteristics. It can cause deterioration.

For example, M1 may be a doped metal different from Ni or Mn of <Formula 1>. Specifically, in <Formula 1>, M1 may be Mo. Or, for another example, the M1 may include at least one of Nb, Ta, and W. The M2 may be F or Cl. More specifically, M1 may be Mo, and M2 may be F.

In general, looking at the structure of LiMn ₂ O ₄ containing manganese used as a positive electrode active material, Li ions are in the tetrahedron (8a) site, and Mn ions (Mn ³⁺ /Mn ⁴⁺ ) are in the octahedral (16d) site, and O ^2- ions are located in the octahedral (16c) site. These ions form a cubic closed-packing arrangement. The tetrahedral site of 8a shares a face with the octahedral site of 16c, which has an empty site around it, to form a three-dimensional channel to provide a passage through which Li ⁺ ions can easily move.

Spinel LiMn ₂ O ₄ electrochemically, when the amount of Li is 0≤x≤1, intercalation/deintercalation of lithium occurs in the 4V region, and when 1≤x≤2, the 3V region Intercalation/deintercalation of lithium occurs in Looking at the structural change according to the amount of lithium, a composition with x≤1 shows a cubic spinel structure with a space group of Fd3m, and a composition with 1≤x≤2 changes a cubic symmetry to a tetragonal system. Evidence of this structural change can be confirmed through voltage plateaus in the charge/discharge curve of LiMn ₂ O ₄ . However, LiMn ₂ O ₄ has a smaller discharge capacity than other active materials such as LiCoO ₂ and LiNiO _2, and the discharge capacity rapidly decreases during high-rate charging and discharging, and due to the elution of manganese during continuous charging and discharging at high voltage, the battery life is rapidly reduced. There is a problem of deterioration.

On the other hand, the positive electrode active material having a 5V class spinel structure according to the present embodiment contains nickel (Ni) and manganese (Mn) together as shown in <Formula 1>, but controls the composition of nickel (Ni) and manganese (Mn), and M1 By further doping M2 and M2, high capacity and cycle characteristics can be exhibited even at a high voltage of 5V. Specifically, the M1 is doped by a wet method, and the M2 is doped by a dry method to further stabilize the structure of the positive electrode active material having a 5V class spinel structure, whereby the oxidation number is +3 Mn ion and +4 valency. The content of M1 and M2 can be controlled so that the average oxidation number of Mn ions is less than 3.5 to 4.

The positive electrode active material having a 5V class spinel structure according to the present embodiment is prepared by adding M1, a transition metal having an oxidation number of 5 or +6, in a wet method in the process of preparing a precursor containing nickel, manganese and oxygen of the positive electrode active material. By preparing by doping, the content range (Mn+3/Mn+4) of manganese ions, which is +3 and +4 of the oxidation number of manganese, can be primarily controlled. Subsequently, the precursor containing M1 along with nickel, manganese and oxygen is dry-mixed with a lithium compound and a doping source containing M2 using a ball mill, and then calcined, thereby manganese which is +3 or +4 of the oxidation number of manganese. The content range of ions (Mn+3/Mn+4) can be secondarily controlled. Here, with respect to the total amount of manganese ions in which the oxidation number is +3 and +4, Mn having the oxidation number of +3 may be 0.3% to 3.38%.

When M1 is a transition metal having an oxidation number of +6, the α value in the <Formula 1> may have a greater influence on the amount of change in the average oxidation number of Mn than the β value. Specifically, in the positive electrode active material of the 5V class spinel structure, the M1 uses Mo with an oxidation number of +6, but by adding it in the step of making a precursor in the form of a solution, the Mo is substituted at the Mn site, and manganese oxidation By primarily controlling the valences +3 and +4 within a relatively large range, the overall structural stability of the positive electrode active material can be secured.

The M2 includes F, and may be provided in the form of NH ₄ F or NH ₄ HF ₂ . The M2 may be mixed with the precursor and the lithium compound in the form of a powder by a ball mill. For example, it may be mixed at room temperature for 6 to 24 hours and fired at high temperature to prepare a positive electrode active material having a 5V class spinel structure. In the process of mixing and sintering, some of the M2 diffuses into the inside of the positive electrode active material and is substituted for an oxygen site, and some may remain on the surface. The M2 is substituted in the oxygen site, thereby controlling the oxidation number of manganese +3 and +4 with a reflective effect, and controlling the oxidation number of manganese more precisely than M1, thereby improving structural stability on the surface of the positive electrode active material. Accordingly, the positive electrode active material having a 5V class spinel structure according to the present exemplary embodiment does not deteriorate in capacity even during initial charging and discharging, and can secure stable cycle characteristics.

In the positive electrode active material having a 5V class spinel structure according to an embodiment of the present invention represented by the above <Formula 1>, the oxidation number of Li is +1, the oxidation number of Ni is +2, and the oxidation number of O is -2. , Since the oxidation number of F is -1, the average oxidation number A of Mn can be calculated as in the following <Equation 1>, and in <Equation 1>, B may be the oxidation number of M.

<Equation 1>

For example, when M is 1 mol% of molybdenum (Mo) having an oxidation number of +6, and F is 0 mol%, when α=0.01, x=0.5, y=1.5, and β=0, In the positive electrode active material having a spinel structure according to an embodiment of the present invention, the average oxidation number of Mn may be 3.9866.

In addition, when M is 1 mol% of molybdenum (Mo) having an oxidation number of +6, and F is 1 mol%, α=0.01, x=0.5, y=1.5, and β=0.01, In the positive electrode active material having a spinel structure according to an embodiment, the average oxidation number of Mn may be 3.9799.

In other words, Mn ions having an oxidation number of +4 are more than Mn ions having an oxidation number of +3, but Mn ions having an oxidation number of +4 may decrease, and Mn having an oxidation number of +3 may increase. That is, A decreases due to the addition of molybdenum, so that Mn ions having an oxidation number of +3 may increase.

As described above, the positive electrode active material having a 5V-class spinel structure according to an embodiment of the present invention may include Mn ions in which oxidation numbers of +4 and +3 are mixed by the doping metal, including fluorine, and Mn The oxidation number of ions can be controlled more precisely. In addition, the surface of the positive electrode active material particles may be prevented from being deteriorated by HF by fluorine.

According to an embodiment, in <Formula 1>, M is molybdenum (Mo) having an oxidation number of +6, x=0.5, y is 1.5, 0<α≤0.01, and 0<β≤0.01. In other words, the positive electrode active material may be doped with 1 mol% or less of each of fluorine and molybdenum in oxides containing lithium, nickel, and manganese. Accordingly, A may be 3.9662 or more or less than 4. Specifically, the fluorine and molybdenum may be 0.5 mol% to 1 mol%, respectively, and A may be 3.9662 or more or 3.9967 or less. More specifically, each of the fluorine and molybdenum is 1 mol%, and the A may be 3.9799.

On the contrary, when any one of fluorine and molybdenum is not doped, or the doping amount of molybdenum is 2 mol% or more, or the doping amount of fluorine is 2 mol% or more, the capacity may be reduced, or the capacity may be decreased depending on the number of charge and discharge times. However, as described above, according to the exemplary embodiment of the present invention, the oxide containing lithium, nickel, and manganese is doped with fluorine and molybdenum at the same time, and the doping amounts of fluorine and molybdenum may be controlled to be 1 mol% or less. Accordingly, a positive electrode active material having a spinel structure having improved capacity and lifetime characteristics may be provided.

A method of manufacturing a positive electrode active material having a 5V class spinel structure according to an embodiment of the present invention is described.

A transition metal aqueous solution containing nickel and manganese, and a doped metal aqueous solution containing a doped metal may be prepared. According to an embodiment, the transition metal aqueous solution may include nickel sulfate and manganese sulfate.

Preparing the doped metal aqueous solution may include preparing a sodium hydroxide solution, and dissolving the powder containing the doped metal in the sodium hydroxide solution.

By supplying the transition metal aqueous solution, the doping metal aqueous solution, and an ammonia solution to a reactor, a cathode active material precursor doped with the doped metal may be prepared in a transition metal hydroxide including nickel and manganese.

According to an embodiment, as described above, the doped metal aqueous solution may be prepared using sodium hydroxide solution, and thus, the introduction of a pH adjuster into the reactor may be omitted. In other words, by introducing the doped metal aqueous solution into the reactor, the doped metal is doped and the pH of the reactor may be controlled.

According to another embodiment, when it is not easy to adjust the pH with the doped metal aqueous solution, a pH adjusting agent (eg, sodium hydroxide solution) may be additionally added.

The positive electrode active material precursor, a lithium salt, and a doping source containing fluorine are dry-mixed and fired using a ball mill to prepare a positive electrode active material having a spinel structure doped with the doped metal and fluorine in nickel, manganese, and lithium oxide. I can.

Hereinafter, a positive electrode active material and a method of manufacturing the same according to a specific experimental example of the present invention will be described.

Preparation of cathode active material according to Experimental Example 1

After adding 4.5 liters of distilled water to the co-precipitation reactor (capacity of 30 liters, output of a rotary motor of 750 W or more), N ₂ gas is supplied to the reactor at a rate of 8 liters/minute and stirred at 450 rpm while maintaining the temperature of the reactor at 45°C. I did. A metal aqueous solution with a concentration of 2 M with a molar ratio of nickel sulfate and manganese sulfate of 25:75 was 0.187 liters/hour, an ammonia solution having a concentration of 10.5 M was 0.043 liters/hour, and a sodium hydroxide solution having a concentration of 4 M was 0.196 liters/hour [Ni _0.25 Mn _0.75 ](OH) ₂ [Ni _0.25 Mn _0.75 ] (OH) ₂ Metal composite hydroxide was prepared by continuously adding it to the reactor for 20 to 25 hours.

The prepared [Ni _0.25 Mn _0.75 ](OH) ₂ metal composite hydroxide was washed with water, filtered, and then dried in a vacuum dryer at 110° C. for 12 hours. After mixing the metal complex hydroxide, lithium carbonate (Li ₂ CO ₃ ), and ammonium fluoride (NH ₄ F) at a molar ratio of 2:1:0.1, heating at a temperature increase rate of 2°C/min, at 500°C By firing for 5 hours and 15 hours at 900°C, LiNi _0.5 Mn _1.5 O _3.99 F _0.01 positive electrode active material powder was prepared.

Preparation of cathode active material according to Experimental Example 2

Perform the same method as in Experimental Example 1 described above, but the metal complex hydroxide, lithium carbonate (Li2CO3), and ammonium fluoride (NH4F) were mixed for 12 hours using a ball mill at room temperature in a molar ratio of 2:1:0.2. , LiNi _0.5 Mn _1.5 O _3.98 F _{0.02 A} cathode active material powder was prepared.

Preparation of cathode active material according to Experimental Example 3

Na2MoO4 powder was dissolved in 0.47M in 0.1L of 4M sodium hydroxide solution. The prepared solution was dissolved in 4.9 L of a 4M sodium hydroxide solution to prepare an aqueous doped metal solution in which Mo was dissolved.

After adding 4.5 liters of distilled water to the co-precipitation reactor (capacity of 30 liters, output of a rotary motor of 750 W or more), N2 gas was supplied to the reactor at a rate of 8 liters/minute, and the reactor was stirred at 450 rpm while maintaining the temperature at 45°C. . A metal aqueous solution with a concentration of 2 M with a molar ratio of nickel sulfate and manganese sulfate of 25:75 at 0.187 liters/hour, and a 10.5 M ammonia solution at 0.043 liters/hour was continuously added to the reactor for 20 to 25 hours, pH For the adjustment and Mo addition, the doped metal aqueous solution was supplied at 0.206 liters/hour to prepare [Ni _0.25 Mn _0.745 Mo _0.005 ](OH) ₂ metal complex hydroxide.

The prepared [Ni _0.25 Mn _0.745 Mo _0.005 ](OH) ₂ metal complex hydroxide was washed with water, filtered, and then dried in a vacuum dryer at 110° C. for 12 hours. The metal complex hydroxide alc lithium carbonate (Li ₂ CO ₃ ) was mixed at a molar ratio of 2:1, heated at a heating rate of 2°C/min, and then calcined at 500°C for 5 hours and 900°C for 15 hours to obtain LiNi _0.5 Mn _1.49 Mo _0.01 O _{4 A} cathode active material powder was prepared.

Preparation of cathode active material according to Experimental Example 4

The same method as in Experimental Example 3 described above was carried out, but in the aqueous doped metal solution in which Mo was dissolved, Na ₂ MoO ₄ powder was dissolved in 0.1 L of sodium hydroxide solution having a concentration of 4 M at a concentration of 0.94 M. The prepared solution was prepared and used by dissolving it in 4.9 L of a 4M sodium hydroxide solution.

The prepared [Ni _0.25 Mn _0.74 Mo _0.01 ](OH) ₂ metal composite hydroxide was washed with water, filtered, and then dried in a vacuum dryer at 110° C. for 12 hours. After mixing the metal complex hydroxide and lithium carbonate (Li ₂ CO ₃ ) at a molar ratio of 2:1, heating at a heating rate of 2° C./min, firing at 500° C. for 5 hours and 900° C. for 15 hours, LiNi _0.5 Mn _1.48 Mo _0.02 O ₄ positive electrode active material powder was prepared.

Preparation of cathode active material according to Experimental Example 5

By performing the same method as in Experimental Example 3 described above, [Ni _0.25 Mn _0.745 Mo _0.005 ](OH) ₂ metal composite hydroxide was prepared.

The prepared [Ni _0.25 Mn _0.745 Mo _0.005 ](OH) ₂ metal complex hydroxide was washed with water, filtered, and then dried in a vacuum dryer at 110° C. for 12 hours. The metal complex hydroxide, lithium carbonate (Li ₂ CO ₃ ), and ammonium fluoride (NH ₄ F) were mixed in a molar ratio of 2:1:0.1 at room temperature using a ball mill for 12 hours, and then the temperature was raised by 2°C/min. After heating at a rate, it was calcined at 500° C. for 5 hours and at 900° C. for 15 hours to prepare LiNi _0.5 Mn _1.49 Mo _0.1 O _3.99 F _0.01 positive electrode active material powder.

Preparation of cathode active material according to Experimental Example 6

By performing the same method as in Experimental Example 3 described above, [Ni _0.25 Mn _0.745 Mo _0.005 ](OH) ₂ metal composite hydroxide was prepared.

The prepared [Ni _0.25 Mn _0.745 Mo _0.005 ](OH) ₂ metal complex hydroxide was washed with water, filtered, and then dried in a vacuum dryer at 110° C. for 12 hours. The metal complex hydroxide, lithium carbonate (Li ₂ CO ₃ ), and ammonium fluoride (NH ₄ F) were mixed in a molar ratio of 2:1:0.2 using a ball mill at room temperature for 12 hours, and then the temperature was raised by 2°C/min. After heating at a speed, it was calcined at 500° C. for 5 hours and at 900° C. for 15 hours to prepare LiNi _0.5 Mn _1.49 Mo _0.1 O _3.98 F _0.02 positive electrode active material powder.

Preparation of cathode active material according to Comparative Example 1

By performing the same method as in Experimental Example 1 described above, [Ni _0.25 Mn _0.75 ](OH) ₂ metal composite hydroxide was prepared.

The prepared [Ni _0.25 Mn _0.75 ](OH) ₂ metal composite hydroxide was washed with water, filtered, and then dried in a vacuum dryer at 110° C. for 12 hours. The metal complex hydroxide and lithium carbonate (Li ₂ CO ₃ ) were mixed at a molar ratio of 2:1, heated at a heating rate of 2°C/min, and fired at 500°C for 5 hours and 900°C for 15 hours to LiNi _0.5 Mn _1.5 O ₄ positive electrode active material powder was prepared.

The positive electrode active materials according to Experimental Examples 1 to 6 and Comparative Example 1 are organized as shown in Table 1 below.

	Mo	F	A
Experiment Example 1	-	1 mol%	3.9933
Experiment Example 2	-	2mol%	3.9867
Experiment Example 3	1 mol%	-	3.9866
Experiment Example 4	2mol%	-	3.9730
Experimental Example 5	1 mol%	1 mol%	3.9799
Experimental Example 6	1 mol%	2mol%	3.9662
Comparative Example 1	-	-	4

In Table 1, A values for each of Experimental Examples 1 to 6 and Comparative Example 1 are described using <Equation 1> described above.

1 is a graph measuring the discharge capacity of a secondary battery including a positive electrode active material according to Experimental Examples 1 to 6 and Comparative Example 1 of the present invention, and FIG. 2 is an Experimental Example 1 to Experimental Example of the present invention of the present invention. 6, is a graph measuring the discharge capacity according to the number of times of charging and discharging of a secondary battery including the positive electrode active material according to Comparative Example 1, and FIG. 3 is a graph showing the positive electrode active material according to Experimental Examples 1 to 6 and Comparative Example 1 of the present invention. This is a graph obtained by normalizing the discharge capacity according to the number of charge/discharge times of the included secondary battery.

1 to 3, a lithium secondary battery including the positive electrode active material according to Experimental Examples 1 to 6 and Comparative Example 1 was prepared, and the discharge capacity was measured at 0.1C condition, and at 0.5C condition. The change in discharge capacity according to the number of charging and discharging was measured at.

As shown in FIG. 1, the prepared Experimental Examples 1 to 6 and Comparative Example 1 were charged to 5V at 0.1C (14mA/g) and then the discharge capacity was checked. As can be seen from FIGS. 1 to 2, according to Comparative Example 1 (pristine), when a positive electrode active material having a 5V spinel structure in which Mo and F are not doped is included, the initial capacity is only 120mAhg ^-1 , and while the cycle proceeds It was confirmed that the capacity gradually decreased. On the other hand, according to Experimental Example 3 (Mo 1mol%), Experimental Example 4 (Mo 2mol%), Experimental Example 5 (Mo 1mol% + F 1mol%) and Experimental Example 6 (Mo 1mol% + F 2mol%), Mo and/ Alternatively, when the F-doped spinel-structured positive electrode active material is included, it can be confirmed that the initial capacity is 130mAhg ^-1 or more, which is superior to that of Comparative Example 1 (pristine), and the degree of capacity reduction is also in the course of the cycle. It can be seen that it is lower than (pristine). However, in the case of the positive electrode active material doped with only 1 mol% of F according to Experimental Example 1, the initial capacity increase was not substantially large, and in the case of the positive electrode active material doped with only 2 mol% of F according to Experimental Example 2, Mo and F were not doped. Compared with the positive electrode active material according to Comparative Example 1, it can be seen that the initial capacity is rather low.

In addition, as can be seen in FIGS. 2 and 3, in the case of the positive electrode active material doped with 1 mol% of Mo and F, respectively, according to Experimental Example 5, the initial capacity is the highest, as well as the decrease in capacity depending on the number of charge and discharge, compared Compared with Example 1, Experimental Examples 1 to 4, and Experimental Example 6, it can be seen that it is significantly smaller.

That is, it can be seen that doping 1 mol% of Mo and F to a positive electrode active material having a spinel structure containing oxides of lithium, nickel, and manganese, respectively, is an efficient method of improving the life characteristics as well as improving the capacity of the lithium secondary battery. have.

4 is a graph showing XPS results of positive electrode active materials according to Experimental Examples 1 to 6 and Comparative Example 1 (pristine) of the present invention.

Referring to FIG. 4, XPS was measured for the positive electrode active materials according to Experimental Examples 1 to 6, and Comparative Example 1. As can be seen from Figure 4, it can be seen that the oxidation number of Mn contained in the positive electrode active material is +3 and +4.

In addition, it can be seen that the ratio of Mn having an oxidation number of +3 and Mn having an oxidation number of +4 is changed according to the mol% of Mo and the mol% concentration of F doped in the positive electrode active material.

In the above, the present invention has been described in detail using preferred embodiments, but the scope of the present invention is not limited to specific embodiments, and should be interpreted by the appended claims. In addition, those who have acquired ordinary knowledge in this technical field should understand that many modifications and variations can be made without departing from the scope of the present invention.

The positive electrode active material, a method of manufacturing the same, and a lithium secondary battery including the same according to an embodiment of the present invention can be applied to electric vehicles, ESSs, and portable electronic devices.

Claims (9)

1. It is represented by the following <Chemical Formula 1>,

   In the <Formula 1>, the oxidation number of Mn includes +3 and +4, and x>0, y>0, 0<β<4, 0<α<0.03, M1 is +5 or + 6 is a transition metal, M2 is an element with an oxidation number of -1,

   The average oxidation number of Mn is less than 3.5 to 4, but the average oxidation number of Mn decreases as the α value or β value increases,

   5V class spinel structure positive electrode active material including x+y=2:

   <Formula 1>

   LiNi _x Mn _y-α M1 _α O _4-β M2 _β
2. The method of claim 1,

   0<α<2, 0<β<2,

   The positive electrode active material having a 5V class spinel structure, wherein Mn is 0.3% to 3.38% of Mn having the oxidation number of +3 and the total amount of the oxidation number of +3 and +4.
3. The method of claim 1,

   The average oxidation number A of Mn is calculated by the following <Equation 1>,

   <Equation 1>

   

   In <Equation 1>, B is a positive electrode active material having a 5V class spinel structure, including the oxidation number of M.
4. The method of claim 1,

   When M1 is a transition metal having an oxidation number of +6, the α value has a greater influence on a change in the average oxidation number of Mn than the β value. 5V class spinel structure positive electrode active material.
5. The method of claim 1,

   In <Formula 1>,

   A positive electrode active material having a 5V class spinel structure including 0<α≤0.01 and 0<β≤0.01.
6. The method of claim 1,

   In <Formula 1>, M1 includes at least one of Nb, Mo, Ta, and W,

   The M2 is F or Cl 5V class spinel structure cathode active material.
7. Preparing a transition metal aqueous solution containing nickel and manganese, and a doped metal aqueous solution containing M1;

   Supplying the transition metal aqueous solution, the doping metal aqueous solution, and an ammonia solution to a reactor to prepare a cathode active material precursor doped with the M1 in transition metal hydroxides containing nickel and manganese; And

   The cathode active material precursor, lithium salt, and a doping source containing M2 are dryly mixed and fired using a ball mill to prepare a spinel structure cathode active material doped with the M1 and M2 in nickel, manganese, and lithium oxide Including steps,

   The step of preparing the doped metal aqueous solution,

   Preparing a sodium hydroxide solution; And

   Including the step of dissolving the powder containing M1 in the sodium hydroxide solution,

   M1 is a transition metal having an oxidation number of +5 or +6, and M2 is an element having an oxidation number of -1. A method of manufacturing a positive electrode active material having a 5V class spinel structure.
8. The method of claim 7,

   The positive electrode active material includes those represented by the following <Chemical Formula 1>,

   In the <Formula 1>, the oxidation number of Mn includes +3 and +4, and x>0, y>0, 0<β<4, 0<α<0.03, M1 is +5 or + 6 is a transition metal, M2 is an element with an oxidation number of -1,

   The average oxidation number of Mn is less than 3.5 to 4, but decreases as the α value or β value increases,

   Method for producing a positive electrode active material having a 5V class spinel structure including x+y=2:

   <Formula 1>

   LiNi _x Mn _y-α M1 _α O _4-β M2 _β
9. The method of claim 7,

   Depending on the concentration of M1 in the doping metal aqueous solution and the mixed concentration of the doping source including M2, the concentration of M1 and the concentration of M2 in the positive electrode active material are controlled,

   A method for manufacturing a 5V class positive electrode active material comprising controlling an average oxidation number of manganese in the positive electrode active material according to the concentration of M1 and M2 in the positive electrode active material.

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