KR101443359B1 - Manufacturing method of nickel rich lithium-nickel-cobalt-manganese composite oxide, nickel rich lithium-nickel-cobalt-manganese composite oxide made by the same, and lithium ion batteries containing the same - Google Patents

Abstract

The present invention relates to a process for producing a lithium-nickel-cobalt-manganese composite oxide having a high nickel content, a lithium nickel-cobalt-manganese composite oxide having a high nickel content produced thereby, and a lithium secondary battery comprising the lithium- .
The method for producing a lithium-nickel-cobalt-manganese composite oxide according to the present invention has high uniformity of particles produced by applying wet pulverization and spray drying, and can freely control the particle size. Particularly, according to the production method of the present invention, since the particle size can be made smaller than that of the conventional coprecipitation method, the lithium-nickel-cobalt-manganese composite oxide having a high initial charge- can do.

Description

TECHNICAL FIELD The present invention relates to a method for producing a lithium-nickel-cobalt-manganese composite oxide having a high nickel content, a lithium-nickel-cobalt-manganese composite oxide having a high nickel content and a lithium secondary battery comprising the lithium- LITHIUM-NICKEL-COBALT-MANGANESE COMPOSITE OXIDE, NICKEL RICH LITHIUM-NICKEL-COBALT-MANGANESE COMPOSITE OXIDE MADE BY THE SAME, AND LITHIUM ION BATTERIES CONTAINING THE SAME}

The present invention relates to a process for producing a lithium-nickel-cobalt-manganese composite oxide having a high nickel content, a lithium nickel-cobalt-manganese composite oxide having a high nickel content produced thereby, and a lithium secondary battery comprising the lithium- .

2. Description of the Related Art In recent years, with the progress of portable and wireless devices, there has been a growing demand for a lithium secondary battery that is small, lightweight, and has a high energy density. As such a cathode active material for a secondary battery, lithium and a transition metal such as LiCoO ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNiO ₂ , LiNi _0.8 Co _0.2 O ₂ , LiMn ₂ O ₄ and LiMnO ₂ , Are known.

Among them, a lithium secondary battery using lithium cobalt oxide (LiCoO ₂ ) as a cathode active material and carbon such as lithium alloy, graphite, and carbon fiber as a cathode has a high voltage of 4 V, Have been widely used.

However, there is a problem that a cobalt source which is a raw material of the lithium cobalt composite oxide is rare and expensive. In addition, a lithium ion secondary battery using a lithium-cobalt composite oxide as an anode is very unstable in a charged state, and is liable to ignite, and low safety is a serious problem.

Accordingly, a lithium-nickel-cobalt-manganese (Li-Ni-Co-Mn) -containing composite oxide (Li-Ni-Co-Mn) containing an element such as manganese which is inexpensive and naturally abundant and which is stable even in a charged state, Has attracted attention as a cathode active material. Recently this LiCoO ₂ as a nickel material having a layered crystal structure, the most attention as an alternative material-manganese and nickel-cobalt-manganese are each 1 mixed with _{1 Li [Ni 1/2 Mn 1/2]} O 2 and Li [ Ni _1/3 Co _1/3 Mn _1/3 ] O ₂ , and the like.

Techniques related to the production of Li-Ni-Mn composite oxide in which a part of Ni sites are substituted with Mn and Li-Ni-Mn-Co composite oxide in which Mn and Co are substituted are well known. For example, U.S. Patent No. 5,264,201 discloses a solid-phase method in which a hydroxide or oxide of nickel (Ni) and manganese (Mn) is mixed with an excess amount of lithium hydroxide, or a method in which an oxide of nickel and manganese is added to an aqueous solution in which lithium hydroxide is saturated in an aqueous solution A slurry is prepared, and the slurry is dried under reduced pressure in a vacuum and then calcined to obtain Li _x Ni _{2-x y} Mn _y O ₂ (0.8? X? 1.0, _y? 0.2). Japanese Patent Application No. Hei 8-171910 discloses a method of mixing an alkali solution with a mixed aqueous solution of manganese and nickel to coprecipitate manganese and nickel to mix lithium hydroxide with the coprecipitated compound and then firing to obtain LiNi _x Mn _1-x O ₂ Lt; = 0.95). A typical process for producing Li [Ni _1/2 Mn _1/2 ] O ₂ and Li [Ni _1/3 Co _1/3 Mn _1/3 ] O ₂ is to use two or three elements simultaneously Precipitates to obtain a precursor in the form of hydroxide or oxide, and this precursor is mixed with lithium hydroxide and fired.

However, when such a coprecipitation reaction method as a liquid phase reaction is applied to the production of a lithium-nickel-cobalt-manganese composite oxide, the cost of the process for synthesizing a NiCoMn (OH) ₂ precursor is very high for mass production, It is difficult to ensure the uniformity of the waste water. In addition, since the NaOH and NH ₄ OH used during the manufacturing process are released into the waste water and contaminate the environment, there is a problem that a separate waste water purification facility is needed to prevent this.

Japanese Patent Publication No. 8-171910

The present invention aims to provide a process for producing a lithium-nickel-cobalt-manganese composite oxide having a high nickel content by applying a new concept of wet pulverization and spray drying.

The present invention also provides a lithium-nickel-cobalt-manganese composite oxide produced by the production method of the present invention and a lithium secondary battery using the composite oxide.

The present invention has been made to solve the above problems

(i) a lithium compound, a nickel compound, a manganese compound, a cobalt compound, an X-containing compound (wherein X is at least one element selected from the group consisting of B, Mg, Al, Si, Ti, V, Cr, Zn, Ga, Zr, And Y-containing compound (wherein Y is any element selected from the group consisting of F, P, and S) in a stoichiometric ratio;

ii) dispersing the compound of i) in a solvent and wet pulverizing until it contains particles having an average particle diameter of less than about 0.3 [mu] m to produce a slurry;

iii) spray drying the slurry of ii) using a pneumatic spray nozzle; and

iv) wherein the iii) spraying the one consisting of the dried slurry to the step of firing _{LiNi 1-a Co b Mn c} X d Y e O 2-e ( where a = b + c of, 0.1≤a≤0.25, b? c, 0? d? 0.1, 0? e? 0.5, and a + b + c + d = 1).

In the present invention, the nickel compound, Ni (OH) _2, NiO, NiOOH, NiCO ₃ and 2Ni (OH) ₂ and 4H ₂ O, NiC ₂ O ₄ and _{2H 2 O, Ni (NO 3} ) 2 and 6H ₂ O, NiSO ₄ , NiSO ₄ .6H ₂ O, fatty acid nickel, and nickel halide, and the manganese compound is selected from the group consisting of Mn ₂ O ₃ , MnO ₂ , Mn ₃ O ₄ , MnCO ₃ , Mn _{3) 2,} MnSO _4, manganese acetate, dicarboxylic acid manganese, manganese citrate, manganese fatty acid manganese, oxy-hydroxides and is selected from the group consisting of halides of manganese chloride, as the cobalt compound include Co (OH) _2, A group composed of CoO, Co ₂ O ₃ , Co ₃ O 4, CoOOH, Co (OCOCH ₃ ) ₂揃 4H ₂ O, CoCl ₂ , Co (NO ₃ ) ₂揃 6H ₂ O, Co (SO 4) ₂揃 7H ₂ O Wherein the lithium compound is selected from the group consisting of Li ₂ CO ₃ , LiNO ₃ , LiNO ₂ , LiOH, LiOH.H ₂ O, LiH, LiF, LiCl, LiBr, LiI, CH ₃ COOLi, Li ₂ O, Li ₂ SO ₄ , It is composed of acetic acid Li, dicarboxylic acid Li, citric acid Li, fatty acid Li, alkyl lithium, and lithium halide Is selected from the group. It is preferable to select a compound which is excellent in reactivity from the above-mentioned compounds and is likely to form voids in the secondary particles of the spray-dried product.

In the present invention, the wet pulverization is carried out by an intermediate pulverization method using water as a solvent and using a beads mill, a ball mill, and an attrition mill together, The medium is pulverized by pulverizing with a solvent in a wet pulverizer. The ceramic medium includes a ceramic rod or a ball.

Here, the solvent means an organic solvent such as an alcohol or water, and preferably water is used. If organic solvent is used, it is advantageous in terms of grinding efficiency and particle size control, but it has disadvantage that cost is increased, and when water is used, the process is simplified and cost can be saved.

When water is used as the solvent, its amount to be used is preferably 1 to 10 parts by weight per 1 part by weight of the compound of i). If the amount of the water used is less than 1 part by weight, it is impossible to crush due to the viscosity increase. If the amount is more than 10 parts by weight, the productivity of the compound particles of i) relative to the volume of water is low. The grinding time needs to be appropriately controlled due to the difference in grinding power depending on the grinding equipment, and the particle size can be appropriately controlled by controlling the grinding time.

The nitrogen-containing additive can be added during the wet pulverization process, whereby the acidification of the mixture before and after the pulverization and the high viscosity of the slurry after pulverization can be solved. Examples of the nitrogen-containing additive include amines, ammonia, ammonium compounds, amino acids, and combinations thereof. Examples of the ammonium compounds include ammonium hydroxide, ammonium carbonate, ammonium acetate, ammonium phosphate, ammonium oxalate, ammonium bicarbonate, And the like, and amino acids such as arginine and lysine can be used. The content of the nitrogen-containing additive is preferably 0.5 to 20 moles per 100 moles of the compound of i). When the content is less than 0.5 mol, phenomena such as acidification and high viscosity of the slurry after crushing appear. When the content exceeds 20 mol, there arises a problem that the molar ratio of the compound becomes unbalanced. In view of economical efficiency, pulverization at 3000 to 4000 rpm is preferable from the viewpoint of efficiency.

After iii) In the step, the ii) a slurry by spray drying (spray drying) of a step, the primary particles are aggregated to obtain a spray-dried body obtained by forming the secondary particles. In the spray drying, a liquid droplet that is atomized by an atomizer is instantaneously dried and powdered by contacting with heated air. The spraying apparatus is not particularly limited, but the nozzle used in the spraying apparatus of the present invention controls the particle size And a pneumatic spray nozzle for spraying at the same time with compressed air is used. However, the particle diameter can be controlled by appropriately selecting the spraying type, pressurized gas flow rate, drying temperature, and the like.

Then, in the production of the lithium-nickel-manganese composite oxide by firing the obtained spray dried body, it is preferable that the spray drying is 100 ° C or higher and 300 ° C or lower. If the temperature during spray drying is too high, there is a possibility that the obtained granulated particles have a large hollow structure and the filling density of the spray dried product may be lowered. On the other hand, if the temperature during spray drying is too low, there is a possibility that problems such as sticking or clogging of the spray drying body due to moisture condensation at the outlet portion may occur.

According to the present invention, in the firing step, the spray dried body is subjected to heat treatment at 850 캜 to 920 캜 for 5 hours to 10 hours in an oxygen-containing gas atmosphere. If the sintering temperature is too high at the time of heat treatment for the spray dried product, the primary particles excessively grow and the sintering between the particles proceeds excessively, and the specific surface area becomes excessively small. On the other hand, if the heat treatment temperature of the above spray-dried product is too low, abnormalities are mixed, crystal structure is not developed, and lattice strain is increased. The firing temperature may be 700 to 1200 ° C, preferably 850 to 920 ° C. If the firing time is excessively long, it is preferable to perform firing for 5 to 10 hours since cracking is required after that, or cracking is difficult.

The present invention also provides a lithium secondary battery comprising the lithium-nickel-cobalt-manganese composite oxide produced by the production method of the present invention and the lithium-nickel-cobalt-manganese composite oxide.

The lithium-nickel-cobalt-manganese composite oxide produced by the production method of the present invention is represented by LiNi _1-a Co _b Mn _c X _d O _{2 -e} Y _e , and the content of nickel (Ni) is 0.6 moles or more It is possible to maintain the structural stability while improving the charge / discharge capacity, and it is more economical.

In the present invention, the lithium-nickel-cobalt-manganese composite oxide has a particle diameter of 5 to 10 탆 and a tap density of 1.8 to 2.6 g / cm 2.

In lithium metal composite oxide particles, primary particles aggregate to form secondary particles. The smaller the secondary particle size, the better the electric conductivity of the metal composite oxide. If the particle size is large, a large amount of active material can not be filled within the limited electrode plate volume, and a high capacity can not be realized. Therefore, in the cathode active material for a secondary battery comprising the metal composite oxide of the present invention, it is important to make the particle size small.

According to the production method of the present invention, the particle diameter of the complex oxide can be freely adjusted, and the particle diameter can be made smaller than that of the conventional production method using the coprecipitation reaction method, so that a large amount of active material can be filled within a limited electrode plate volume , Resulting in high capacity.

The process for preparing a lithium-nickel-cobalt-manganese composite oxide according to the present invention is a new concept of wet pulverization and spray drying for the production of a lithium-nickel-cobalt-manganese composite oxide, Unlike the case where the process is applied, there is no process design cost and wastewater generation, and the particle size can be freely adjusted while the uniformity of the generated particles is high. Particularly, according to the production method of the present invention, since the particle size can be made smaller than that of the conventional coprecipitation method, the lithium-nickel-cobalt-manganese composite oxide having a high initial charge- can do.

1 is a SEM photograph of a cathode active material prepared according to one embodiment of the present invention and a comparative example.
2 is a SEM photograph of the cathode active material prepared according to one embodiment of the present invention.
FIG. 3 shows the results of analysis of cross-sections of the cathode active material prepared according to one embodiment of the present invention and a comparative example.
FIG. 4 shows charge / discharge test results in a battery including a cathode active material prepared according to one embodiment of the present invention and a comparative example.
FIG. 5 is a graph showing rate capability in a battery including a cathode active material according to an embodiment of the present invention and a comparative example.

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 >

And then weighed so as to have a stoichiometric ratio of Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ by using Li ₂ CO _3, Ni (OH) ₂ , Mn ₃ O ₄ and Co (OH) ₂ as starting materials, To prepare a slurry so that the solid / liquid ratio becomes 5: 5.

The raw materials were stirred at 400 rpm for 10 minutes in a stirrer so as to be uniformly mixed, and then pulverized and dispersed at a high speed in a wet grinding apparatus (Mincer, Netzsch) to form a slurry. A zirconia bead mill having a diameter of 0.65 mm was used for wet grinding and dispersing, and the grinding time was fixed to 30 minutes at 3500 rpm. The slurry was pulverized and dispersed until the particle size (D50) of the particles in the pulverized slurry became 0.3 mu m, and the viscosity of the slurry was adjusted to 500 cp or less.

The drying and molding of the slurry was carried out by using a spray dryer as an Ain system product using a nozzle of a pneumatic spray type Co-current type and setting the hot air temperature to 250 to 300 ° C, the hot air temperature to 100 to 150 ° C, And spray-dried under pressure to prepare a precursor. About 100 g of the powder thus prepared was placed in a crucible made of alumina, and fired at 880 캜 for 10 hours under an air flow of 5 L / min (at a heating rate of 3 캜 / min) to obtain a lithium-nickel-manganese-cobalt composite oxide powder.

≪ Comparative Example 1 &

Precursors were prepared twice in the same manner as in Example 1 except that the co-current type pneumatic spray nozzle was spray-dried at a pressure of 3.0 bar using a centrifugal spray nozzle, and each case was compared with Comparative Example 1-1 , And Comparative Example 1-2.

≪ Comparative Example 2 &

Ni _0.6 Co _0.2 Mn _0.2 (OH) ₂ having the same composition as in Example 1 was prepared through a general coprecipitation reaction method, and the prepared Ni _0.6 Co _0.2 Mn _0.2 (OH) ₂ was uniformly mixed with Li ₂ CO ₃ After the mixture was heated to a temperature of 920 ° C at a heating rate of 3 ° C / min and then heated at a constant temperature for 8 hours to 10 hours in an oxidizing atmosphere at a flow rate of 5 L / min, Li [Ni _0.6 Mn _0.2 Co _0.2 ] O ₂ .

≪ Experimental Example 1 > SEM measurement and tap density measurement

SEM photographs of the active materials of Example 1, Comparative Examples 1-1, 1-2, and Comparative Example 2 were measured, and the results are shown in FIG.

As shown in FIG. 1, the particle size of the spray-dried particles of the present invention was in the range of 5 to 10 μm and exhibited a uniform size. In the case of Comparative Examples 1-1 and 1-2 dried with a centrifugal atomization type atomizer type nozzle, the particle diameter was in the range of 13 to 22 μm and in the case of Comparative Example 2 in the coprecipitation reaction method, the particle diameter was in the range of 13 to 22 μm It can be seen that it is possible to reduce the size of the particles when the spray-drying is performed on the nozzle of the pneumatic spray type Co-current type according to the embodiment of the present invention.

The tap density of the precursor particles of Example 1, Comparative Examples 1-1, 1-2, and Comparative Example 2 was measured using a tap density meter (INTEC, ATD-200).

The tap density of the active material was 1.8 to 2.2 g / cm ² in Example 1, which was spray-dried with a nozzle of a pneumatic spray atomizing type Co-current type, 2, the tap density of the active material was 2.2 to 2.6 g / cm < ^{2 &} gt ;.

≪ Experimental Example 2 >

The cross section of the precursor of Example 1 prepared by spray-drying after wet pulverization of the present invention and the precursor of Comparative Example 2 prepared by the coprecipitation reaction method were analyzed, and the results are shown in FIG.

As shown in FIG. 2, in the case of the embodiment of the present invention in which the wet pulverization is followed by spray drying, the composition of each of Ni, Co, and Mn metals after the heat treatment is partially reduced, Co, and Mn were uniformly distributed.

≪ Examples 2 to 5 >

The procedure of Example 1 was repeated except that Li ₂ CO _3, Ni (OH) ₂ , Mn ₃ O ₄ , and Co (OH) ₂ were used as starting materials and the mixture was mixed at a stoichiometric ratio To prepare a lithium-nickel-cobalt-manganese composite oxide.

division Cathode active material composition Example 1 Li [Ni _0.60 Co _0.20 Mn _0.20 ] O ₂ Example 2 Li [Ni _0.65 Co _0.17 Mn _0.18 ] O ₂ Example 3 Li [Ni _0.7 Co _0.15 Mn _0.15 ] O ₂ Example 4 Li [Ni _0.75 Co _0.12 Mn _0.13 ] O ₂

≪ Experimental Example 3 > SEM measurement and tap density measurement

SEM photographs of the active materials of Examples 1 to 4 were measured and the results are shown in Fig. The size of the unit particles (primary particles) of the positive electrode active material was 5 to 10 mu m and the tap density was 1.8 to 2.4 g / cm < ² >.

≪ Preparation Example >

A battery was prepared in order to evaluate the battery characteristics of the cathode active material for lithium secondary battery manufactured in Examples 1 to 4 and Comparative Examples 1 to 2 and Comparative Example 2.

The resultant mixture was uniformly mixed so that the ratio of the conductive paste (Super P) to the binder (PVDF) was 92: 4: 4. The mixture was spread evenly on an aluminum foil, compressed uniformly at a pressure of 1 ton in a roll press, and vacuum dried in a vacuum oven at 100 캜 for 12 hours to prepare a positive electrode substrate for a lithium secondary battery. Using lithium foil as a counter electrode on the positive electrode, SK product as a separator, and 1 mole of LiPF ₆ solution in a mixed solvent of EC / EMC = 1/3 of Technosemichem as an electrolyte were used as a liquid electrolyte, Half coin cell of the standard size was manufactured.

≪ Experimental Example 4 >

≪ Experimental Example 4-1 >

The half-cell batteries prepared in Examples 1 to 4 and Comparative Example 2 were subjected to electrochemical analysis at 25 ° C in a voltage range of 3.0 to 4.3 V, 0.1, 0.2, 0.5, 1.0 (manufactured by Toyo Corporation, Toscat 3100, Japan) , 1.5, and 2.0 C, respectively. The results are shown in FIG. 4 and Table 2 below.

4 is a graph showing a voltage curve obtained by performing 0.1 C charging / discharging at a cut-off of 3.0 to 4.3 V. FIG. As shown in FIG. 4 and Table 2, the initial discharge capacity and the initial reversible efficiency of the active materials of Examples 1 to 4 prepared by spray-drying after wet pulverization were higher than those of Comparative Example prepared by the coprecipitation method .

division 1 ^st discharge capacity
[@ 0.1 C, mAh / g] 1 ^st reversible efficiency
[@ char / disch,%] Rate characteristic
[@ 1.0 / 0.1C,%] Life characteristics
[@ 30cyc.,%] Example 1
Ni _0.60 Mn _0.20 Co _0.20 177.5 88.0 93.3 97.9 Comparative Example 1-2
Ni ₀ . ₆₀ Mn _0.20 Co _0.20 177.1 86.4 93.2 97.1 Example 2
Ni _0.65 Mn _0.18 Co _0.17 182.6 87.4 92.7 98.5 Example 3
Ni _0.70 Mn _0.15 Co _0.15 185.6 87.5 92.5 95.5 Example 4
Ni _0.75 Mn _0.13 Co _0.12 189.3 86.1 92.2 95.6 Comparative Example 2
Ni _0.60 Mn _0.20 Co _0.20 173.9 87.0 91.9 93.5

≪ Experimental Example 4-2 >

5 is a graph showing the rate capability of Examples 1 to 4 and Comparative Example 2 for 0.1C to 6C. FIG. 5 shows that the active material prepared by spray drying using the pneumatic spray nozzle after the wet mixing according to the embodiment of the present invention has a significantly improved rate characteristic than the active material of the comparative example.

Claims (7)

(i) a lithium compound, a nickel compound, a manganese compound, a cobalt compound, an X-containing compound (wherein X is at least one element selected from the group consisting of B, Mg, Al, Si, Ti, V, Cr, Zn, Ga, Zr, And Y-containing compound (wherein Y is any one element selected from the group consisting of F, P and S) in a stoichiometric ratio;
ii) dispersing the compounds of i) in a solvent and wet milling until the particles contain particles having an average particle diameter of less than 0.3 mu m to produce a slurry;
iii) spray drying the slurry of ii) using a pneumatic atomizing nozzle; and
iv) heat-treating the spray-dried slurry of iii) in an oxygen-containing gas atmosphere at 850 ° C to 920 ° C for 5 hours to 10 hours
_{LiNi 1-a Co b Mn c} X d O 2-e Y e ( where a = b + c, 0.1≤a≤0.4, b≤c, 0≤d≤0.1, 0≤e≤0.5, a + b + c + d = 1)
Wherein the lithium-nickel-cobalt-manganese composite oxide has a particle diameter of 5 to 10 占 퐉 and a tap density of 1.8 to 2.6 g / cm2.
The method according to claim 1,
The nickel _{compounds, Ni (OH) 2, NiO} , NiOOH, NiCO 3 and 2Ni (OH) 2 and 4H2O, NiC ₂ O ₄ and _{2H 2 O, Ni (NO 3} ) 2 and 6H ₂ O, NiSO _4, NiSO ₄ .6H2O, fatty acid nickel, and nickel halide,
The manganese compound is selected from the group consisting of Mn ₂ O ₃ , MnO ₂ , Mn ₃ O ₄ , MnCO ₃ , Mn (NO ₃ ) ₂ , MnSO ₄ , manganese acetate, manganese dicarboxylate, manganese citrate, Lt; RTI ID = 0.0 > of manganese < / RTI > chloride,
As the cobalt compound, Co (OH) ₂ , CoO, Co ₂ O ₃ , Co ₃ O 4, CoOOH, Co (OCOCH ₃ ) ₂揃 4H ₂ O, CoCl ₂ , Co (NO ₃ ) ₂揃 6H ₂ O, ) ₂ < ₇ > H ₂ O,
The lithium compound is _{Li 2 CO 3, LiNO 3,} LiNO 2, LiOH, LiOH and _{H 2 O, LiH, LiF,} LiCl, LiBr, LiI, CH 3 COOLi, Li 2 O, Li 2 SO 4, acetic acid Li, dicarboxylic Nickel-cobalt-manganese composite oxide, wherein the lithium-nickel-cobalt-manganese composite oxide is selected from the group consisting of lithium hexafluorophosphate Li, lithium citrate Li, fatty acid Li, alkyl lithium and lithium halide.
The method according to claim 1,
The method for producing a lithium-nickel-cobalt-manganese composite oxide, which comprises using water as a solvent at the time of wet milling in the step ii) and pulverizing the mixture at 3000 to 4000 rpm using a ceramic medium.
delete A lithium-nickel-cobalt-manganese composite oxide produced by the production method of any one of claims 1 to 3.
delete A lithium secondary battery comprising the lithium-nickel-cobalt-manganese composite oxide according to claim 5.

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