KR101475288B1 - Li-Ni-Mn Composite Oxide and Method for preparing thereof - Google Patents

Abstract

The present invention relates to a process for producing a Li-Mn-Ni composite oxide and a Li-Mn-Ni composite oxide produced thereby.
The method for producing the Li-Mn-Ni composite oxide of the present invention can control the spherical shape and size of the secondary particles by spray-drying while being easily manufactured by applying solid-phase mixing and wet grinding, The Li-Mn-Ni composite oxide produced by the method has not only excellent structural stability and thermal stability as a layered structure, but also has excellent electrochemical properties.

Description

The present invention relates to a method for producing a Li-Mn-Ni composite oxide and a Li-Mn-Ni composite oxide produced thereby,

The present invention relates to a process for producing a Li-Mn-Ni composite oxide and a Li-Mn-Ni composite oxide produced thereby.

Most of the currently available lithium secondary batteries use LiCoO ₂ having a high voltage of 4 V as a positive electrode active material, and the value of LiCoO ₂ is high because cobalt is expensive.

Accordingly, various positive electrode active materials replacing LiCoO ₂ have been studied, and nickel and manganese have been studied.

In the prior art using a composite oxide of Ni and Mn as a positive electrode active material of a lithium secondary battery, US Patent No. 5393622 discloses a method of dryly mixing Ni hydroxide, hydroxide of Mn and hydroxide of Li at the same time, A method of producing an active material having a composition represented by Li _y Ni _{1 - x} Mn _x O ₂ (where 0? _X ? 0.3, 0? Y? 1.3) which is further heated and calcined after cooling to room temperature has been proposed .

In addition, U.S. Patent No. 5,370,948, the aqueous solution of the Li salt, Ni salt and LiNi1-xMnxO ₂ by mixing Mn salt at a time, and drying and firing the obtained mixture (In the formula, 0.005? X? 0.45).

Conventionally, for the synthesis of such a Li-Ni-Mn composite oxide, a dry mixing method obtained by mixing powders such as NiO, MnO, and LiOH.H ₂ O has been widely used. However, in the case of dry mixing, when the Mn content is high, there is a problem that the homogeneity of the atoms is insufficient, the impurity phase is contained, the crystallinity is low, and sufficient electrochemical characteristics can not be obtained.

On the other hand, in the case of using a wet slurry in which powders such as Mn oxides, Ni solution, Li solution and the like are slurried and mixed and baked, the crystallinity and the electrochemical characteristics are improved in comparison with the dry method , And the generation of corrosive gas (gas) such as nitrogen oxides.

When coprecipitated, coprecipitates in the form of hydroxides, carbonates, and oxides can improve the uniform dispersibility of constituent atoms. However, since the hydroxides of manganese dioxide are unstable, there is a possibility that when exposed to the atmosphere, the uniformity of the precursor may be problematic.

Further, Japanese Unexamined Patent Publication 2002-42813 discloses the firing of LiNi _{0 .5} at least 1000 ℃ the synthesis of Mn _{0 .5} O ₂ to the high-temperature Ni-Mn composite hydroxide by coprecipitation as a precursor preferably, less than 850 ℃ , There is a problem in the cycle life during firing.

On the other hand, for the production of LiNi _{1 - X} Mn _x O ₂ in which LiNiO ₂ is substituted with Mn, there is a view that particles can be formed even at a relatively low temperature of about 600 to 800 ° C. However, Japanese Patent Laid- It is rather undesirable to synthesize a lithium-containing complex oxide based on LiNiO ₂ at a high temperature of 800 ° C or higher.

U.S. Patent No. 5393622 U.S. Patent No. 5370948 Japanese Patent Laid-Open No. 2002-42813 Japanese Patent Laid-Open No. 8-171910

The present invention has been made to solve the problems of the prior art as described above, and it is an object of the present invention to provide a method for producing a Li-Mn-Ni composite oxide excellent in electrochemical characteristics such as life characteristics and rate characteristics while exhibiting structural stability with sufficient crystallinity, It is another object of the present invention to provide a Li-Mn-Ni composite oxide produced by the above method.

The present invention has been made to solve the above problems

A lithium source, a nickel source, and a manganese source at an equivalent ratio;

Mixing the mixture with a solvent to prepare a slurry, and pulverizing the slurry by applying mechanical energy;

Spray drying; And

Calcining at a temperature of 800 to 900 占 폚; And a method for producing a Li-Mn-Ni composite oxide represented by the following general formula.

_{[Formula] Li [Ni 0 .6 + 3} x Mn 0 .4-3x] O 2 ( stage 0.01≤x≤0.1)

Unlike conventional Li-Mn-Ni composite oxides, Li-Mn-Ni composite oxide according to the present invention can be easily prepared by solid-phase mixing and wet grinding, There is an advantage in that the shape and size of the spherical shape of the tea particles can be controlled.

In the step of mixing the lithium source, the nickel source and the manganese source in an equivalent ratio, carbonates, hydroxides, sulfates, and phosphates including lithium, nickel, and manganese can be generally used.

The mixture is mixed with a solvent to prepare a slurry. In the step of pulverizing the slurry by applying energy, physical mechanical energy or chemical energy may be applied to pulverize the particles.

As is well known in the present invention, when the ratio of the nickel element contained in the oxide is increased, a disorder occurs in which the lithium ion and the nickel ion are substituted at the time of high-temperature firing, and nickel ions It is preferable to keep the firing temperature at 800 to 900 占 폚 because the mixed cation mixing phenomenon occurs and the movement of lithium ions accompanying charge and discharge is inhibited and the capacity may be lowered.

The method for producing a Li-Mn-Ni composite oxide according to the present invention is a method for producing a Li-Mn-Ni composite oxide which is doped with at least one element selected from the group consisting of Mg, Ti, Cr, Fe, Co, Cu, Zn, Al, Ge, Further comprising the steps of:

The method for producing a Li-Mn-Ni composite oxide according to the present invention is characterized in that the surface of a Li-Mn-Ni composite oxide is formed from a group consisting of Mg, Ti, Cr, Fe, Co, Cu, Zn, By doping at least one selected element, cation mixing phenomenon in which Ni enters the Li layer can be prevented. That is, when the surface of the cathode active material is coated, the transition metal is prevented from being eluted from the surface or the stability of the surface is enhanced at a high voltage, and a small amount of impurities are doped by doping to partially replace the metal sites, This allows for greater capacity or better life than ever before.

The present invention also provides a Li-Mn-Ni composite oxide represented by the following general formula prepared by the production method of the present invention.

_{[Formula] Li [Ni 0 .6 + 3} x Mn 0 .4-3x] O 2 ( stage 0.01≤x≤0.1)

The present invention also provides a method for producing a Li-Mn-Al-based alloy, which is doped with at least one element selected from the group consisting of Mg, Ti, Cr, Fe, Co, Cu, Zn, Al, Ge, Ni composite oxide.

The Li-Mn-Ni composite oxide of the present invention has an α-NaFeO ₂ type crystal structure, that is, a layered structure such as an NCM composite oxide, and a metal oxide layer composed of a transition metal and oxygen and an oxygen octahedron layer surrounding lithium Since the MO ₂ layer forms a strong ionic bond and the Coulomb repulsion between the MO ₂ and MO ₂ layers acts, lithium ions can intercalate / deintercalate and diffuse along the two-dimensional plane, .

The Li-Mn-Ni composite oxide of the present invention is a composite oxide in which primary particles are aggregated and formed secondary particles, and the D ₅₀ of the secondary particles is 10 to 15 탆, and the average particle diameter of the primary particles is 0.5 to 3 mu m.

In the Li-Mn-Ni composite oxide of the present invention, when the particle diameter of the primary particles is as large as 3 m or more, the reaction area of the lithium-containing complex oxide becomes large and the number of active sites increases. A binder used for forming an electrode mixture layer of the electrode; And the non-aqueous electrolyte and the lithium-containing complex oxide tend to occur irreversibly. As a result, a problem may arise in that the composition (paste, slurry, etc.) containing the solvent used for forming the electrode mixture layer is gelated because gas is generated in the electrochemical device to deform the casing. Therefore, in the Li-Mn-Ni composite oxide of the present invention, it is important to control the particle diameter of the primary particles.

The Li-Mn-Ni composite oxide of the present invention is characterized in that an exothermic peak due to a differential scanning calorimeter is 270 DEG C or more, and the heat stability is very high.

The Li-Mn-Ni composite oxide of the present invention is characterized in that the arrangement of oxygen atoms constitutes a cubic dense structure. The Li-Mn-Ni composite oxide of the present invention has a layer structure in which Ni atoms and Mn atoms are solved at the atomic level, and the arrangement of oxygen exhibits a cubic dense structure.

The method for producing the Li-Mn-Ni composite oxide of the present invention can control the spherical shape and size of the secondary particles by spray drying, while facilitating the production by applying solid-phase mixing and wet grinding, The Li-Mn-Ni composite oxide prepared by the method of the present invention has a layered structure, which is excellent in structural stability and thermal stability, and has excellent electrochemical properties.

FIG. 1 shows SEM photographs of a Li-Mn-Ni composite oxide prepared according to an embodiment of the present invention.
FIG. 2 shows XRD measurement results according to the compositional change of the Li-Mn-Ni composite oxide prepared in one embodiment of the present invention.
FIG. 3 shows the result of analyzing the particle size of LiNi _{0 .7} Mn _{0 .3} O ₂ composite oxide prepared in one embodiment of the present invention.
FIGS. 4 and 5 show results of measurement of lifetime characteristics and rate characteristics for a battery including a cathode active material manufactured in an embodiment of the present invention.
FIG. 6 shows SEM photographs of LiNi _{0 .7} Mn _{0 .3} O ₂ composite oxides prepared according to an embodiment of the present invention.
Figure 7 shows the XRD picture for the sintering temperature by LiNi _{0 .7} Mn _{0 .3} O ₂ composite oxide prepared in one embodiment of the present invention.
FIGS. 8 and 9 show the results of measurement of life characteristics and rate characteristics for a battery including a cathode active material according to an embodiment of the present invention.
10 is a SEM photograph of the Mg-doped active material prepared in one embodiment of the present invention.
FIG. 11 shows XRD measurement results of the Mg-doped active material prepared in one embodiment of the present invention.
FIG. 12 shows DSC measurement results of Mg-doped active material and Mg-doped active material prepared in one embodiment of the present invention.

Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited by the following examples.

< Example  1> Li - Mn - Ni Composite oxides

And a lithium source as a source of manganese as a source of nickel, and then calcined at 860 占 폚 to prepare a Li-Mn-Ni composite oxide shown in Table 1 below. As a comparative _{example, LiNi 0 .5 Mn 0 .5 O} 2 .

Example 1-1 Examples 1-2 Example 1-3 Comparative Example 1 LiNi0.65Mn0.35O2 LiNi0.7Mn0.3O2 LiNi0.8Mn0.2O2 LiNi0.5Mn0.5O2

< Experimental Example  1-1> Composition analysis

The compositional analysis of the Li-Mn-Ni composite oxide of Examples 1-1 to 1-3 and Comparative Examples was evaluated, and the results are shown in Table 2.

Example 1-1 Examples 1-2 Example 1-3 Comparative Example 1 division LiNi0.65Mn0.35O2 LiNi0.7Mn0.3O2 LiNi0.8Mn0.2O2 LiNi0.5Mn0.5O2 Contents Ni / (Ni + Co + Mn) 0.647 0.689 0.792 0.497 Mn / (Ni + Co + Mn) 0.353 0.311 0.208 0.503 Impurities Fe [ppm] 32 17 15 21 Al [ppm] - 82 98 67 Ca [ppm] 44 53 48 51 Mg [ppm] 19 26 19 24 Na [ppm] 361 546 390 437 Zn [ppm] - One One - Cu [ppm] One - - - S [ppm] 1054 1304 1069 1120

< Experimental Example  1-2> SEM  Photo measurement

SEM photographs of the Li-Mn-Ni composite oxide of Examples 1-1 to 1-3 and Comparative Examples prepared in the above Examples were measured, and the results are shown in FIG. As shown in FIG. 1, the size of the primary particles is in the range of 1 to 3 μm, but the size of the primary particles varies depending on the composition.

< Experimental Example  1-3> XRD  Measure

Example 1-2 The LiNi _{0 .7} Mn _{0 .3} O ₂ composite oxide prepared in the XRD measurements whether to form a layered structure and the results are shown in Figure 2. Comparative Example LiNi ₀ of Umicore as _0.5 exhibited XRD measurement results for Co _{0 .2} Mn _{0 .3} O ₂ together. FIG. 2 shows that the Li-Mn-Ni composite oxide prepared in Example 1-2 of the present invention exhibits a layered structure.

< Experimental Example  1-4> Particle size analysis

The particle size of LiNi _{0 .7} Mn _{0 .3} O ₂ composite oxide prepared in Example 1-2 was analyzed and the results are shown in FIG. 3 and Table 3. As a result of the analysis of average particle diameter, D ₅₀ of LiNi _{0 .7} Mn _{0 .3} O ₂ composite oxide was measured to be 12 μm.

division PSD Particle size distribution D ₁₀ D ₅₀ D ₉₀ D _max 4.81 12.28 31.09 69.18

< Manufacturing example > Battery Manufacturing

Denka black was added to the binder (PVDF 8%) and uniformly stirred at a high speed. Then, the cathode active materials of Examples 1 and 2 were added and stirred uniformly with a high-speed stirrer for 20 min or more. At this time, the composition ratio of the slurry was 92: 4: 4 (active material: Binder: conductive material).

The uniformly mixed slurry was applied to a uniformly spread Al foil with a constant thickness, with a Loading Level of 9.0 ± 1.0 mg / cm ² . Al Foil coated with slurry was first dried at 130 ° C for 1 hour and then rolled. The thickness of the coating after rolling was 32.0 ± 1.0 μm and the rolling density was 2.5 ± 0.1 g / cm ³ . Vacuum Oven After drying at 100 ° C for 3 hours, an electrode plate was finally prepared. The prepared electrode was cut using punch and welded to the anode can. The anode Can was welded with a Ni mesh, and then the coin cell was assembled in a glove box or a dry room.

< Experimental Example  1-5> By composition  Measurement of life characteristics and rate characteristics

The life characteristics and the rate characteristics of the batteries including the cathode active materials of Examples 1-1 to 1-3 prepared in the above Production Example were measured and the results are shown in Tables 4, 4 and 5, respectively.

Example 1-1 Examples 1-2 Example 1-3 Comparative Example 1 division LiNi _{0 .65} Mn _{0 .35} O ₂ LiNi _{0 .7} Mn _{0 .3} O ₂ LiNi _{0 .8} Mn _{0 .2} O ₂ LiNi _{0 .5} Mn _{0 .5} O ₂ 0.2C 155.9 161.6 174.8 132.4 7C / 0.2C 64.6 71.9 69.6 58.1 Cycle @ 50 122.1 131.1 122.8 102.2

In Table 4, FIG. 5, and FIG. 6, it can be seen that the Li-Ni-Mn oxide of the present invention is significantly improved in life characteristics and rate characteristics than LiNi _0.5 Mn _0.5 O ₂ of the comparative example.

< Example  2> By firing temperature Li - Mn - Ni Composite oxides

In order to investigate the structural and electrochemical properties of the Li-Ni-Mn composite oxide according to the present invention, the calcination temperature was 860 ° C. for the composition of LiNi _{0 .7} Mn _{0 .3} O ₂ of Example 1-2, 880 and 900 ° C, composite oxides Examples 2-1, 2-2 and 2-3 were prepared.

< Experimental Example  2-1> By firing temperature SEM  Photo measurement

FIG. 6 shows SEM photographs of LiNi _{0 .7} Mn _{0 .3} O ₂ composite oxides of Examples 2-1 to 2-3 prepared at different firing temperatures in Example 2. In FIG. 6, it can be seen that as the firing temperature rises, the size of primary particles grows.

< Experimental Example  2-2> By firing temperature XRD  Measure

Embodiment is shown in Example 2-1 to Example 2-3 firing temperature by LiNi _{0 .7} Mn _{0 .3} O ₂ 7 photographs the XRD for the compound oxide. It can be seen from FIG. 7 that even if the firing temperature is changed, the crystal structure does not change greatly.

< Experimental Example  2-3> Measurement of lifetime characteristics and rate characteristics by firing temperature

The life characteristics and the rate characteristics of the batteries including the cathode active materials of Examples 2-1 to 2-3 were measured according to the firing temperatures, and the results are shown in Tables 4, 8, and 9, respectively. When the firing temperature was 860 ℃, the life characteristics and the rate characteristics were the highest.

< Example  3> Surface Doped Li [ Ni0 .7 Mn0 .3] O2 active material preparation

The active material of Examples 3-1 to 3-3 was prepared by surface coating with addition of Al, Mg, and An salts solution to Li [Ni _{0 .7} Mn _{0 .3} ] O ₂ active material. Li [Ni _0.7 Mn _0.3 ] O ₂ active material not doped was prepared as a comparative example.

< Experimental Example  3-1> by doping element SEM  Photo measurement

SEM photographs of the active materials of Examples 3-1 to 3-3 in which doping was performed by adding Al, Mg, and An salt solutions were measured, and the results are shown in FIG.

< Experimental Example  3-1> After doping XRD  Measure

The XRD of the Mg-doped active material prepared in Example 3-2 was measured and the results are shown in FIG. It can be confirmed that the layered structure is maintained even after Mg doping in FIG.

< Experimental Example  3-2> According to doping Thermal stability  Measure

DSC was measured for the Mg-doped active material prepared in Example 3-2 and the Mg-doped non-doped active material, and the results are shown in FIG.

In FIG. 12, it can be seen that the temperature of the heat generation starting point after the Mg doping is increased, and the intensity of the exothermic peak is decreased, thereby increasing the structural stability and thermal stability by Mg doping.

Claims (8)

A lithium source, a nickel source, and a manganese source at an equivalent ratio;
Mixing the mixture with a solvent to prepare a slurry, and pulverizing the slurry by applying mechanical energy;
Spray drying;
Firing the mixture at a temperature of 800 to 900 DEG C to produce a Li-Mn-Ni composite oxide represented by the general formula below; And
[General Formula] Li [Ni _{0.6 + 3x} Mn _0.4-3x ] O ₂ ( _{0.01? X? 0.1} )
Doping the surface with at least one element selected from the group consisting of Mg, Ti, Cr, Fe, Co, Cu, Zn, Al, Ge and Sn,
The production of a Li-Mn-Ni composite oxide represented by the above general formula and doped with at least one element selected from the group consisting of Mg, Ti, Cr, Fe, Co, Cu, Zn, Al, Way.
delete delete A method of manufacturing a semiconductor device, which is manufactured by the manufacturing method of claim 1 and is represented by the general formula and doped with at least one element selected from the group consisting of Mg, Ti, Cr, Fe, Co, Cu, Zn, Al, Li-Mn-Ni-based composite oxide.
5. The method of claim 4,
Wherein the Li-Mn-Ni composite oxide has an? -NaFeO ₂ type crystal structure.
5. The method of claim 4,
Wherein the Li-Mn-Ni-based composite oxide is a composite oxide in which primary particles are aggregated and formed secondary particles, the D ₅₀ of the secondary particles is 10 to 15 탆, Lt; RTI ID = 0.0 &gt; Li-Mn-Ni &lt; / RTI &gt;
5. The method of claim 4,
Wherein the Li-Mn-Ni composite oxide exhibits an exothermic peak at 270 占 폚 or higher by a differential scanning calorimeter.
5. The method of claim 4,
Wherein the arrangement of oxygen atoms constituting the Li-Mn-Ni composite oxide is a cubic closest packing.

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