JPWO2018043436A1 - Heterogeneous metal-containing lithium nickel composite oxide and method for producing the same - Google Patents

Abstract

General formula (1): Li x (Ni 1-y My) O 2 + δ (1) [wherein, M represents at least one selected from the group consisting of Ge, Sn, Al, Co, and Mn. x, y and δ each represent 0.8 ≦ x ≦ 1.4, 0 <y ≦ 0.500, −0.20 ≦ δ ≦ 0.20. ] Has a high capacity, and the deterioration of the cycle characteristics is significantly suppressed.

Description

  The present invention relates to a dissimilar metal-containing lithium nickel composite oxide and a method for producing the same.

  Lithium-containing composite oxides are used as positive electrode active materials for lithium ion secondary batteries. Lithium ion secondary batteries are expected to be used not only for power supplies for mobile phones and notebook computers, but also for medium-sized and large-sized power supplies such as those for vehicles and power load leveling systems It is done.

  Among the lithium-containing composite oxides, lithium nickelate is expected as a 4V class positive electrode material having a high specific capacity (200 mAh / g). However, it is known that lithium nickelate significantly deteriorates its cycle characteristics when it is charged to a high voltage (upper limit voltage: 4.3 V) or higher in order to obtain a high capacity.

  Under these circumstances, the present inventors have found that a lithium mixed metal oxide having a specific crystal structure and a specific parameter suppresses deterioration of cycle characteristics while maintaining high capacity. (See Patent Document 1 below).

  However, in applications where long life is required, such as in-vehicle use and stationary use, materials in which deterioration of cycle characteristics is further suppressed are required.

JP, 2013-56801, A

  The present invention has been made in view of the above-mentioned prior art, and it is an object of the present invention to provide a lithium-containing composite oxide having high initial charge and discharge efficiency and in which deterioration of cycle characteristics is significantly suppressed. Do.

  As a result of intensive studies to achieve the above-described purpose, the present inventors have surprisingly found that a lithium nickel composite oxide having a specific composition has high initial charge / discharge efficiency and cycle characteristics. It has been found that the deterioration is significantly suppressed. The present inventors have completed the present invention by conducting further studies based on such findings.

That is, the present invention includes the inventions described in the following sections.
Item 1. General formula (1):
Li _x (Ni _1-y M _y ) O _{2 + δ} (1)
[Wherein, M represents at least one selected from the group consisting of Ge, Sn, Al, Co and Mn. x, y and δ each represent 0.8 ≦ x ≦ 1.4, 0 <y ≦ 0.500, −0.20 ≦ δ ≦ 0.20. ]
A lithium nickel composite oxide represented by
Item 2. The lithium nickel composite oxide according to Item 1, wherein M is Ge, Sn, Al or Mn, or a combination of Al and Co.
Item 3. 3. The lithium nickel composite oxide according to item 1 or 2, which contains a crystal phase of a hexagonal layered rock salt type structure or a crystal phase of a monoclinic layered rock salt type structure.
Item 4. 4. A lithium nickel composite oxide according to item 3 above, which comprises only a crystal phase of a hexagonal layered rock salt type structure or a crystal phase of a monoclinic layered rock salt type structure.
Item 5. It is a manufacturing method of lithium nickel type complex oxide in any one of said claim | item 1-4,
A first step of mixing a lithium compound, a metal M compound, and nickel hydroxide and / or a water-soluble nickel salt in an aqueous solvent, and firing the mixture obtained in the first step under an oxidizing atmosphere A manufacturing method comprising a second step.
Item 6. The method according to item 5, wherein the first step is a step of adding a metal M compound and nickel hydroxide and / or a water-soluble nickel salt to an aqueous solution containing a lithium compound.
Item 7. The positive electrode material for lithium ion secondary batteries containing the lithium nickel-type composite oxide in any one of said claim | item 1-4.
Item 8. 8. A lithium ion secondary battery comprising the positive electrode material for a lithium ion secondary battery according to item 7 above.

  By using the lithium nickel composite oxide of the present invention as a positive electrode active material for a lithium ion secondary battery, it is possible to provide a lithium ion secondary battery having high initial charge / discharge efficiency and exhibiting high cycle characteristics. It becomes possible.

FIG. 2 is a diagram showing an X-ray diffraction pattern of the sample obtained in Example 1. FIG. 2 is a diagram showing the results of charge and discharge tests of the sample obtained in Example 1. FIG. 6 is a view showing an X-ray diffraction pattern of the sample obtained in Example 2. FIG. 7 is a diagram showing the results of charge and discharge tests of the sample obtained in Example 2. FIG. 6 is a view showing an X-ray diffraction pattern of the sample obtained in Example 3. FIG. 7 is a diagram showing the results of charge and discharge tests of the sample obtained in Example 3. It is a figure which shows the X-ray-diffraction pattern of the sample obtained by the comparative example 1. FIG. It is a figure which shows the result of the charging / discharging test of the sample obtained by the comparative example 1. FIG. FIG. 6 is a view showing an X-ray diffraction pattern of the sample obtained in Example 4. FIG. 7 is a diagram showing the results of charge and discharge tests of the sample obtained in Example 4. FIG. 6 is a view showing an X-ray diffraction pattern of the sample obtained in Example 5. In the drawing, the upper right portion shows a view in which the diffraction angle 2θ is in the vicinity of 17 to 32 °. FIG. 7 is a diagram showing the results of charge and discharge tests of the sample obtained in Example 5.

  Hereinafter, the present invention will be described in detail.

1. Lithium-Nickel Composite Oxide The present invention includes a lithium-nickel composite oxide. The lithium nickel composite oxide of the present invention has a general formula (1):
Li _x (Ni _1-y M _y ) O _{2 + δ} (1)
[Wherein, M represents at least one selected from the group consisting of Ge, Sn, Al, Co, and Mn. x, y and δ each represent 0.8 ≦ x ≦ 1.4, 0 <y ≦ 0.500, −0.20 ≦ δ ≦ 0.20. ]
It is a compound represented by

  In the above general formula (1), M represents at least one selected from the group consisting of Ge, Sn, Al, Co, and Mn. M may be one kind alone or a combination of two or more kinds. As combinations of two, combinations of Ge and Sn, Ge and Al, Sn and Al, Ge and Co, Ge and Mn, Sn and Co, Sn and Co, Sn and Mn, Al and Co, Al and Mn, and Co and Mn are used. Examples of the three combinations include, for example, combinations of Ge, Sn and Al, and Al, Co and Mn. In the case of a combination of two or more, the ratio is not particularly limited, and can be appropriately determined. Moreover, among them, M is preferably Ge, Sn, Al or Mn, or a combination of Al and Co, more preferably Ge, Sn or Al, particularly preferably Ge or Al preferable.

In the above general formula (1), x corresponds to a molar ratio of Li to Ni and M (Li / (Ni + M)). If x is less than 0.8, the capacity is reduced, and if x is more than 1.4, the crystal structure changes to a monoclinic LiNiO ₂ -Li ₂ NiO ₃ -based solid solution with inferior battery characteristics, so x is , 0.8 ≦ x ≦ 1.4. Further, from the viewpoint of obtaining a positive electrode active material with high cycle characteristics, 0.8 ≦ x ≦ 1.3 is preferable, and 0.9 ≦ x ≦ 1.3 is more preferable.

  In the above general formula (1), y is 0.0 <y ≦ 0.500, preferably 0.001 ≦ y ≦ 0.300, and more preferably 0.001 ≦ y ≦ 0.200. With such a range, the initial charge and discharge efficiency and the cycle characteristics can be improved.

  In the above general formula (1), δ corresponds to the nonstoichiometry of the amount of oxygen. δ is −0.20 ≦ δ ≦ 0.20, preferably −0.15 ≦ δ ≦ 0.15, and more preferably −0.10 ≦ δ ≦ 0.10.

Examples of the lithium nickel composite oxide represented by the above general formula (1) include Li _1.1 (Ni _0.9 Ge _0.1 ) O ₂ , Li _1.02 (Ni _0.9973 Ge _{0. 0027) O 2, Li 1.1 (} Ni 0.9 Sn 0.1) O 2, Li 1.14 (Ni 0.989 Sn 0.011) O 2, Li 1.1 (Ni 0.9 Al 0 _.1 ) O ₂ , Li _1.00 (Ni _0.919 Al _0.081 ) O ₂ , Li _1.00 (Ni _0.8 Co _0.15 Al _0.05 ) O ₂ , and Li _1.00 Ni _0.7 Mn _0.3 ) O _{2 and the} like can be mentioned.

  The lithium nickel-based composite oxide of the present invention has a space group:

Crystal phase or space group of hexagonal layered rock salt type structure belonging to:

It is preferable to include a crystal phase of a monoclinic layered rock salt type structure belonging to The lithium nickel-based composite oxide of the present invention only needs to contain the crystal phase of the above-mentioned hexagonal layered rock salt type structure or the crystal phase of monoclinic layered rock salt type structure, and other crystalline phases of rock salt type structure (for example, , A cubic rock salt type structure etc.). When it is a mixed phase, the proportion of the crystal phase of the hexagonal layered rock salt type structure or the crystal phase of the monoclinic layered rock salt type structure is based on the whole mixed phase from the viewpoint of the initial charge / discharge efficiency and cycle characteristics (100 weight 50% to 90% by weight is preferable as%). Further, the lithium nickel composite oxide of the present invention may be composed of only the crystal phase of the above-mentioned hexagonal layered rock salt type structure or the crystal phase of the monoclinic layered rock salt type structure.

  For example, in the lithium nickel composite oxide represented by the above general formula (1), when M is Ge, Sn, or Al or a combination of Al and Co, a hexagonal layered rock salt type structure It is easy to obtain a lithium nickel composite oxide containing the crystal phase of (1), and when M is Mn, it is easy to obtain a lithium nickel composite oxide containing the crystal phase of monoclinic layered rock salt type structure.

  The lithium nickel-based composite oxide of the present invention has the amount of Ni and M in the Ni layer based on the total amount (100%) of elements present in the Ni layer (3b site) from the viewpoint of the initial charge / discharge efficiency and cycle characteristics. It is preferred that the occupancy of the sum of amounts is at most 99.90%, in particular 70.00 to 99.80%.

  When the lithium nickel composite oxide of the present invention contains a crystal phase of a hexagonal layered rock salt type structure, the lattice constant a is preferably 2.870 Å or less, and is 2.850 Å or more and 2.865 Å or less Is more preferred. On the other hand, when the crystal phase of the monoclinic layered rock salt type structure is included, the lattice constant a is preferably 5.000 Å or less, preferably 4.900 Å or more and 4.980 Å or less, and the lattice constant b is 8.600 Å It is preferable that it is the following, and it is more preferable that it is 8.570 Å or more and 8.590 Å or less. The lattice constant a for the crystal phase of the hexagonal layered rock salt type structure and the lattice constants a and b for the crystal phase of the monoclinic layered rock salt type structure, the positive electrode active material having particularly excellent cycle characteristics It can be done.

  When the lithium nickel composite oxide of the present invention contains a crystal phase of a hexagonal layered rock salt type structure, the lattice constant c is preferably 14.10 Å or more and 14.20 Å or less. On the other hand, when the crystal phase of the monoclinic layered rock salt type structure is included, the lattice constant c is preferably 4.90 Å or more and 5.10 Å or less. When the lattice constant c is in the above range, a positive electrode active material that is particularly excellent in initial charge / discharge efficiency and cycle characteristics can be obtained.

  When the lithium nickel composite oxide of the present invention contains a crystal phase having a hexagonal layered rock salt type structure, the value (c / a) obtained by dividing the lattice constant c by the lattice constant a is 4.940 or more and 4.960 or less Is preferred. When the value (c / a) obtained by dividing the lattice constant c by the lattice constant a is in the above range, a positive electrode active material which is particularly excellent in the initial charge / discharge efficiency and cycle characteristics can be obtained.

  On the other hand, when the crystal phase of the monoclinic layered rock salt type structure is included, it is preferable that an angle β between the a axis and the c axis is 105.0 ° or more and 112.0 ° or less. When the angle β between the a-axis and the c-axis is in the above range, a positive electrode active material that is particularly excellent in initial charge / discharge efficiency and cycle characteristics can be obtained.

Lithium-nickel-based composite oxide of the present invention, when containing a crystal phase of a hexagonal layered rock-salt structure, it is preferable that the lattice volume is 101.00A ³ or less, 99.00A ³ or more 100.90A ³ below Is preferred. On the other hand, if it contains a crystal phase of monoclinic layered rock-salt structure, it is preferable lattice volume is 200.00A ³ or more 202.00A ³ or less. When the lattice volume is in the above range, a positive electrode active material that is particularly excellent in initial charge and discharge efficiency and cycle characteristics can be obtained.

  The crystal structure, the occupancy of the sum of the amounts of Ni and M in the Ni layer, the lattice constants a and c, and the lattice volume all have CuKα as a radiation source, and the measurement range of the diffraction angle 2θ is 10 °. It is determined or calculated by performing powder X-ray diffraction measurement at 125 ° or less and defining a crystal structure as a hexagonal layered rock salt type structure based on the measurement result and performing Rietveld analysis.

2. Method of Producing Lithium Nickel-Based Composite Oxide The present invention further includes a method of producing the above-described lithium nickel-based composite oxide. In the method for producing a lithium nickel composite oxide according to the present invention, a step of mixing a lithium compound, a metal M compound, and nickel hydroxide and / or a water-soluble nickel salt in an aqueous solvent (herein And the step of baking the mixture under an oxidizing atmosphere (sometimes referred to herein as "the second step").

  The lithium compound used in the first step is not particularly limited. For example, lithium hydroxide (including hydrate), lithium carbonate, lithium acetate (including hydrate), lithium nitrate, lithium perchlorate (water And the like. The lithium compound used in the first step is preferably in excess with respect to the number of moles of nickel and metal M charged, and more preferably 1.5 times or more and 2.5 times or less.

  The metal M compound used in the first step is not particularly limited, and examples thereof include oxides, hydroxides, chlorides, sulfates, nitrates, acetates, and hydrates thereof of metal M. Specifically, germanium oxide, sodium stannate, aluminum hydroxide, cobalt nitrate (including hydrate), cobalt hydroxide, manganese chloride (including hydrate), manganese hydroxide and the like can be mentioned.

  A commercially available thing can be used as nickel hydroxide used in a 1st process. Moreover, you may use what is obtained by neutralizing water-soluble nickel salt with an alkali as needed. In this case, nickel hydroxide obtained by previously neutralizing a water-soluble nickel salt with an alkali may be used in the first step, or the water-soluble nickel salt may be introduced into an aqueous solvent to conduct alkali in the system. Nickel hydroxide can also be obtained by neutralization with Examples of water-soluble nickel salts include nitrates, chlorides, sulfates, acetates, and hydrates thereof. The water-soluble nickel salt may be used alone or in combination of two or more.

  The alkali used to neutralize the water-soluble nickel salt is not particularly limited, and, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia or the like can be used. The concentration of the alkali may be a concentration that can maintain pH 11 or more during the neutralization step in which the water-soluble nickel salt is dropped to the alkali. Moreover, it is preferable to set the temperature at the time of a neutralization process to -10 degreeC or more and 50 degrees C or less. By reducing the neutralization temperature, the nucleation rate of nickel hydroxide is increased, and finer, highly reactive nickel hydroxide can be obtained. In particular, an antifreeze solution such as ethanol may be added to the aqueous alkali solution to keep the reaction temperature at 0 ° C. or less. Thus, when making it react at low temperature, it is preferable to use lithium hydroxide as an alkali. This is because the temperature dependency of solubility is flat compared to sodium hydroxide and potassium hydroxide, and therefore alkali precipitation at low temperatures hardly occurs. Moreover, there is also the merit on the process that it is not necessary to remove other alkali ion as a lithium hydroxide impurity, and the remaining lithium hydroxide can also be used as an above-described lithium compound. In order to add the water-soluble nickel salt to the alkali solution at the time of the neutralization step, it is preferable to carry out gradually over several hours by the dropping step in order to obtain uniform nickel hydroxide. In addition, after completion of the dropwise addition, the precipitate may be stirred for several hours or more while blowing air at room temperature to mature the precipitate, if necessary. Furthermore, if necessary, after preparing the precipitate, the precipitate may be washed with distilled water and then filtered in order to remove residual alkali.

  In addition, in the case where a compound containing a metal other than an amphoteric metal (that is, when M is Co or manganese) is used as the metal M compound, nickel hydroxide can be obtained by neutralizing a water-soluble nickel salt with an alkali. When obtained, it is preferable to add a water-soluble salt of metal M as a metal M compound to the water-soluble nickel salt because a homogeneous mixed state is easily obtained and the composition control becomes easy. Such water-soluble salts of metal M include, for example, nitrates, chlorides, sulfates, acetates, and hydrates of these.

  The specific method of the first step is not particularly limited, but in view of the easiness of obtaining the lithium nickel composite oxide of the present invention and the easiness of the production process, metal M in an aqueous solution containing a lithium compound It is preferable to set it as the process of adding a compound and nickel hydroxide and / or water-soluble nickel salt. In this case, the order of adding the metal M compound and the nickel hydroxide to the aqueous solution containing the lithium compound in the first step is not particularly limited, but the ease of obtaining the lithium nickel composite oxide of the present invention and the ease of the production process From the viewpoint of height, it is preferable to add the metal M compound to the aqueous solution containing the lithium compound, and after confirming that the metal M compound is completely dissolved, to add nickel hydroxide.

  In addition, the aqueous solution containing a lithium compound used in the first step is preferably alkaline. The alkali source is not particularly limited, and, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia and the like can be used. It is preferable to first prepare an aqueous solution containing these alkali sources, add and dissolve a metal M compound, and then add a lithium compound. Lithium hydroxide is preferable because it acts not only as an alkali source but also as a lithium compound.

  Moreover, it is preferable that the manufacturing method of lithium nickel complex oxide of this invention includes the process of drying a mixture as needed before providing to the 2nd process mentioned later after the above-mentioned 1st process. The drying method is not particularly limited and can be performed according to a conventional method. For example, there is a method of transferring the mixture obtained in the first step to a container such as a petri dish and putting the mixture in a dryer kept at 50 ° C. or higher for drying for several hours. By the said drying process, the dry powder of the mixture obtained at the 1st process can be prepared. In addition, after drying, before being subjected to the second step, the obtained dried powder may be pulverized if necessary.

  In the method for producing a lithium nickel composite oxide according to the present invention, after the above-mentioned first step, before being subjected to the second step described later, the second step described later under an oxidizing atmosphere, if necessary. A step (hereinafter, referred to as “pre-baking step”) of firing at a temperature (for example, 550 ° C. or lower) lower than the firing temperature in the above may be included. The oxidizing atmosphere is not particularly limited, and examples thereof include the atmosphere in the air and the oxygen stream. The firing time is not particularly limited, and can be, for example, 5 hours or more. Thus, it is preferable to carry out pre-baking before being subjected to the second step described later, because more lithium can be taken in.

  In the second step, the mixture obtained in the first step is fired in an oxidizing atmosphere. The oxidizing atmosphere is not particularly limited, and examples thereof include the atmosphere in the air and the oxygen stream. The firing temperature is preferably 700 ° C. or less, more preferably 600 ° C. or more and 700 ° C. or less, because if the temperature exceeds 700 ° C., the cycle characteristics may be degraded. The firing time is not particularly limited, and can be, for example, about 1 hour to 30 hours.

  In the method for producing a lithium nickel composite oxide according to the present invention, the calcined product obtained in the second step described above is subjected to an oxidizing atmosphere, if necessary, in the same manner as the preliminary baking step described above. You may include the process of baking at the temperature (for example, 550 degrees C or less) lower than the calcination temperature in the above-mentioned 2nd process. The oxidizing atmosphere is not particularly limited, and examples thereof include the atmosphere in the air and the oxygen stream. The firing time is not particularly limited, and can be, for example, 5 hours or more. As described above, it is preferable to carry out baking after the above-mentioned second step, because more lithium can be taken in.

  Moreover, it is preferable that the manufacturing method of lithium nickel type complex oxide of this invention includes the process of cooling the baking products obtained by above-mentioned 2nd process. The method for cooling the fired product is not particularly limited and can be performed according to a conventional method. For example, a method of leaving to about room temperature in a furnace after firing and the like can be mentioned.

  Furthermore, in the method for producing a lithium nickel composite oxide according to the present invention, if necessary, after passing through the above-mentioned cooling step, the step of grinding the obtained fired product, the step of washing, the step of filtering, and the drying It is preferred to include at least one of the steps. The specific method of these steps is not particularly limited, and can be performed according to a conventional method.

3. Positive electrode material for lithium ion secondary battery and lithium ion secondary battery The lithium nickel composite oxide of the present invention described above can be used as a positive electrode material for lithium ion secondary battery. Furthermore, a lithium ion secondary battery (non-aqueous lithium ion secondary battery) having high capacity and excellent cycle characteristics by combining with the positive electrode material for lithium ion secondary battery, the negative electrode, the electrolyte (including the solid electrolyte), and the separator And an all solid lithium ion secondary battery). The negative electrode is not particularly limited, and examples thereof include metal lithium, graphite, a Si-SiO-based negative electrode, and an LTO (Li ₄ Ti ₅ O ₁₂ ) -based negative electrode. The electrolyte is not particularly limited, and an organic electrolytic solution in which LiPF ₆ or the like is used as an electrolyte salt and dissolved in various solvents such as ethyl carbonate (EC) and dimethyl carbonate (DMC), Li ₂ S-P ₂ S ₅ , Li _{2 S-GeS 2 -P 2 S} 5, Li 2 S-SiS 2 -Li 3 PO 4 inorganic sulfide-based solid electrolyte such as, and the like high molecular polymer having lithium ion conductivity. The separator is not particularly limited, and polyethylene, polypropylene and the like can be mentioned.

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

Example 1
Preparation of samples 20.98 g (0.50 mol) of lithium hydroxide monohydrate was added to 200 ml of distilled water and completely dissolved. After 2.62 g (0.025 mol) of germanium oxide was added to the lithium hydroxide solution and completely dissolved, 20.86 g (0.225 mol) of nickel hydroxide was added and dispersed by stirring. The resulting mixture was transferred to a polytetrafluoroethylene petri dish, and the petri dish was placed in a dryer kept at 100 ° C., and was dried for 3 hours. The obtained dry powder was pulverized and mixed, heated to 650 ° C. in an oxygen stream over 1 hour in an electric furnace, and sintered for 20 hours, and then cooled to around room temperature in a furnace to obtain a calcined product . The obtained calcined product was pulverized, washed with distilled water, filtered, and dried at 100 ° C. to obtain a product.

Evaluation by X-Ray Diffraction The actual (+) and calculated (solid line) X-ray diffraction patterns of the product obtained above are shown in FIG. Further, according to Rietveld analysis, the obtained product is a hexagonal LiNiO ₂ single phase having a layered rock salt type structure, the lattice constant a is 2.6418 (4) Å, and the lattice constant c is 14.19540 (17 ), Lattice volume 100.851 (2) Å ³ , c / a value 4.956, Ni and Ge ion occupancy in the Ni layer 92.07 (15)%, Ni and Ge in the Li layer The ion occupancy rate was found to be 0%.

Chemical Analysis : The chemical composition of the product obtained above was determined by ICP emission analysis, and it was found that the Li / (Ni + Ge) ratio is 1.02 and the Ge / (Ni + Ge) ratio is 0.0027.

Evaluation of charge and discharge characteristics After mixing 5 mg of the product obtained above with 5 mg of acetylene black, a positive electrode mixture is prepared using 0.5 mg of polytetrafluoroethylene, and the positive electrode mixture is pressure bonded to an aluminum mesh to obtain a positive electrode. And Then, a coin-type battery is manufactured using the positive electrode, metal lithium as the negative electrode, 1M LiPF ₆ / EC + DMC system (EC indicates ethylene carbonate, DMC indicates dimethyl carbonate) as the electrolyte, and a separator, and the charge / discharge test is performed. went. The charge / discharge test was conducted at the start of charge up to 50 cycles under the conditions of a potential range of 2.2 to 4.8 V, a current density per positive electrode active material: 40 mA / g, and a test temperature of 30 ° C. The results are shown in FIG.

  From FIG. 2, the product obtained in Example 1 has an initial charge capacity of 239 mAh / g, an initial discharge capacity of 217 mAh / g, an initial charge / discharge efficiency of 90.7%, and an average initial discharge voltage of 3.75V. It was found that the initial discharge energy density was 815 mWh / g, the discharge capacity after 50 cycles was 184 mAh / g, and the discharge capacity retention ratio after 50 cycles was 84.7%.

Example 2
Preparation of samples 20.98 g (0.50 mol) of lithium hydroxide monohydrate was added to 200 ml of distilled water and completely dissolved. After 6.67 g (0.025 mol) of sodium stannate was added to the lithium hydroxide solution to dissolve it completely, 20.86 g (0.225 mol) of nickel hydroxide was added and dispersed by stirring. The resulting mixture was transferred to a polytetrafluoroethylene petri dish, and the petri dish was placed in a dryer kept at 100 ° C., and was dried for 3 hours. The obtained dry powder was pulverized and mixed, heated to 625 ° C. in an oxygen stream over 1 hour in an electric furnace, and sintered for 20 hours, and then cooled to around room temperature in a furnace to obtain a calcined product . The obtained calcined product was pulverized, washed with distilled water, filtered, and dried at 100 ° C. to obtain a product.

Evaluation by X-Ray Diffraction The actual (+) and calculated (solid line) X-ray diffraction patterns of the product obtained above are shown in FIG. Further, according to Rietveld analysis, the obtained product is a hexagonal LiNiO ₂ single phase having a layered rock salt type structure, the lattice constant a is 2.86013 (10) Å, and the lattice constant c is 14.1509 (4 ), Lattice volume 100.250 (6) Å ³ , c / a value 4.948, Ni and Sn ion occupancy in the Ni layer 81.12 (18)%, Ni and Sn in the Li layer The ion occupancy was found to be 0.83 (6)%.

Chemical Analysis : When the chemical composition of the product obtained above was determined by ICP emission analysis, it was found that the Li / (Ni + Sn) ratio is 1.14 and the Sn / (Ni + Sn) ratio is 0.011.

Evaluation of charge and discharge characteristics After mixing 5 mg of the product obtained above with 5 mg of acetylene black, a positive electrode mixture is prepared using 0.5 mg of polytetrafluoroethylene, and the positive electrode mixture is pressure bonded to an aluminum mesh to obtain a positive electrode. And Subsequently, a coin-type battery was produced using the positive electrode, metal lithium as the negative electrode, 1 M LiPF ₆ / EC + DMC system as the electrolytic solution, and a separator, and the charge and discharge test was performed. The charge / discharge test was conducted at the start of charge up to 50 cycles under the conditions of a potential range of 2.2 to 4.8 V, a current density per positive electrode active material: 40 mA / g, and a test temperature of 30 ° C. The results are shown in FIG.

  From FIG. 4, the product obtained in Example 2 has an initial charge capacity of 236 mAh / g, an initial discharge capacity of 201 mAh / g, an initial charge / discharge efficiency of 84.8%, and an initial average discharge voltage of 3.72 V, It was found that the initial discharge energy density was 746 mWh / g, the discharge capacity after 50 cycles was 171 mAh / g, and the discharge capacity retention ratio after 50 cycles was 72.6%.

[Example 3]
Preparation of samples 20.98 g (0.50 mol) of lithium hydroxide monohydrate was added to 200 ml of distilled water and completely dissolved. After 1.95 g (0.025 mol) of aluminum hydroxide was added to the lithium hydroxide solution and completely dissolved, 20.86 g (0.225 mol) of nickel hydroxide was added and dispersed by stirring. The resulting mixture was transferred to a polytetrafluoroethylene petri dish, and the petri dish was placed in a dryer kept at 100 ° C., and was dried for 3 hours. The obtained dry powder was pulverized and mixed, heated to 650 ° C. in an oxygen stream over 1 hour in an electric furnace, and sintered for 20 hours, and then cooled to around room temperature in a furnace to obtain a calcined product . The obtained calcined product was pulverized, washed with distilled water, filtered, and dried at 100 ° C. to obtain a product.

Evaluation by X-Ray Diffraction The actual (+) and calculated (solid line) X-ray diffraction patterns of the product obtained above are shown in FIG. Further, according to Rietveld analysis, the obtained product is a hexagonal LiNiO ₂ single phase having a layered rock salt type structure, the lattice constant a is 2.86305 (5) Å, and the lattice constant c is 14.1800 (2 ), Lattice volume is 100.662 (3) Å ³ , c / a value is 4.953, Ni and Al ion occupancy in the Ni layer is 99.78 (19)%, Ni and Al in the Li layer The ion occupancy was found to be 0.09 (7)%.

Chemical Analysis : The chemical composition of the product obtained above was determined by ICP emission analysis, and it was found that the Li / (Ni + Al) ratio is 1.00, and the Al / (Ni + Al) ratio is 0.081.

Evaluation of charge and discharge characteristics After mixing 5 mg of the product obtained above with 5 mg of acetylene black, a positive electrode mixture is prepared using 0.5 mg of polytetrafluoroethylene, and the positive electrode mixture is pressure bonded to an aluminum mesh to obtain a positive electrode. And Subsequently, a coin-type battery was produced using the positive electrode, metal lithium as the negative electrode, 1 M LiPF ₆ / EC + DMC system as the electrolytic solution, and a separator, and the charge and discharge test was performed. The charge / discharge test was conducted at the start of charge up to 50 cycles under the conditions of a potential range of 2.2 to 4.8 V, a current density per positive electrode active material: 40 mA / g, and a test temperature of 30 ° C. The results are shown in FIG.

  From FIG. 6, the product obtained in Example 3 has an initial charge capacity of 230 mAh / g, an initial discharge capacity of 207 mAh / g, an initial charge / discharge efficiency of 90.0%, and an average initial discharge voltage of 3.70 V. It was found that the initial discharge energy density was 766 mWh / g, the discharge capacity after 50 cycles was 171 mAh / g, and the discharge capacity retention ratio after 50 cycles was 82.6%.

Comparative Example 1
Preparation of sample 10.70 g (0.255 mol) of lithium hydroxide monohydrate was added to 200 ml of distilled water and completely dissolved. 23.18 g (0.25 mol) of nickel hydroxide was added to the lithium hydroxide solution and dispersed by stirring. The resulting mixture was transferred to a polytetrafluoroethylene petri dish, and the petri dish was placed in a dryer kept at 100 ° C., and was dried for 3 hours. The obtained dry powder was pulverized and mixed, heated to 700 ° C. in an oxygen stream over 1 hour in an electric furnace, and sintered for 20 hours, and then cooled to around room temperature in a furnace to obtain a calcined product . After firing the obtained fired product, it is heated again to 750 ° C. in an oxygen stream for 1 hour in an electric furnace, fired for 20 hours, and then cooled to around room temperature in the furnace to obtain a fired product. The The obtained calcined product was pulverized, washed with distilled water, filtered, and dried at 100 ° C. to obtain a product.

Evaluation by X-Ray Diffraction The actual (+) and calculated (solid line) X-ray diffraction patterns of the product obtained above are shown in FIG. Further, according to Rietveld analysis, the obtained product is a hexagonal LiNiO ₂ single phase having a layered rock salt type structure, the lattice constant a is 2.87589 (3) Å, and the lattice constant c is 14.19150 (13 ), Lattice volume 100.6489 (18) Å ³ , c / a value 4.935, Ni ion occupancy in the Ni layer 100%, Ni ion occupancy in the Li layer 0.56 (5 It turned out that it is%.

Chemical Analysis : The chemical composition of the product obtained above was determined by ICP emission analysis, and it was found that the Li / Ni ratio is 1.02.

Evaluation of charge and discharge characteristics After mixing 5 mg of the product obtained above with 5 mg of acetylene black, a positive electrode mixture is prepared using 0.5 mg of polytetrafluoroethylene, and the positive electrode mixture is pressure bonded to an aluminum mesh to obtain a positive electrode. And Subsequently, a coin-type battery was produced using the positive electrode, metal lithium as the negative electrode, 1 M LiPF ₆ / EC + DMC system as the electrolytic solution, and a separator, and the charge and discharge test was performed. The charge / discharge test was conducted at the start of charge up to 50 cycles under the conditions of a potential range of 2.2 to 4.8 V, a current density per positive electrode active material: 40 mA / g, and a test temperature of 30 ° C. The results are shown in FIG.

  From FIG. 8, the product obtained in Comparative Example 1 has an initial charge capacity of 259 mAh / g, an initial discharge capacity of 220 mAh / g, an initial charge / discharge efficiency of 84.6%, and an average initial discharge voltage of 3.80 V, Initial discharge energy density is 834 mWh / g, discharge capacity after 30 cycles is 176 mAh / g, discharge capacity maintenance rate after 30 cycles is 80.4%, discharge capacity after 50 cycles is 159 mAh / g, discharge after 50 cycles The capacity retention rate was found to be 72.6%.

Example 4
Preparation of sample Weigh nickel (II) hexahydrate and cobalt (II) nitrate hexahydrate to a molar ratio of 80:15 (0.25 mol / batch), and dissolve in 500 ml of distilled water, An aqueous solution of metal salt was prepared. Next, 500 ml of distilled water was added to another container containing 50 g of sodium hydroxide to completely dissolve it, and kept at 20 ° C. in a thermostat. The aqueous solution of metal salt prepared above was gradually added dropwise over about 3 hours to an aqueous solution of sodium hydroxide to prepare a coprecipitate. Thereafter, the precipitate was matured by bubbling the coprecipitate for 2 days at room temperature using an oxygen gas generator. After aging, the precipitate was washed with water and filtered to obtain a raw material for firing.

  20.98 g (0.50 mol) of lithium hydroxide monohydrate was added to 200 ml of distilled water and completely dissolved. After 0.98 g (0.0125 mol) of aluminum hydroxide was added to the lithium hydroxide solution and completely dissolved, the raw material for baking prepared above was added and dispersed by mixer stirring. The resulting mixture was transferred to a polytetrafluoroethylene petri dish, and the petri dish was placed in a dryer kept at 50 ° C., and was dried for 2 days. The obtained dry powder was pulverized and mixed, heated to 500 ° C. in an oxygen stream for 1 hour in an electric furnace, and sintered for 20 hours, and then cooled to around room temperature in a furnace to obtain a calcined product . After the obtained fired product is crushed, the temperature is raised again to 700 ° C. in an oxygen stream for 1 hour in an electric furnace, firing is performed for 20 hours, and then cooled to around room temperature in the furnace to obtain a fired product. The The product was washed with distilled water, filtered and dried at 100 ° C. to obtain a product.

Evaluation by X-ray Diffraction The actual (+) and calculated (solid line) X-ray diffraction patterns of the product obtained above are shown in FIG. Further, according to Rietveld analysis, it is found that the obtained product is a hexagonal LiNiO ₂ single phase having a layered rock salt type structure, the lattice constant a is 2.85522 (6) Å, and the lattice constant c is 14.1473 (3 ), Lattice volume is 99.881 (4) Å ³ , c / a value is 4.955, Ni, Al and Co ion occupancy in the Ni layer is 98.0 (3)%, in the Li layer It was found that the occupancy of Ni, Al and Co ions was 0%.

Evaluation of charge and discharge characteristics After mixing 5 mg of the product obtained above with 5 mg of acetylene black, a positive electrode mixture is prepared using 0.5 mg of polytetrafluoroethylene, and the positive electrode mixture is pressure bonded to an aluminum mesh to obtain a positive electrode. And Subsequently, a coin-type battery was produced using the positive electrode, metal lithium as the negative electrode, 1 M LiPF ₆ / EC + DMC system as the electrolytic solution, and a separator, and the charge and discharge test was performed. Charge / discharge test starts charging, potential range: 2.2 to 4.8 V (2nd cycle onward: 2.2 to 4.6 V), current density per cathode active material: 40 mA / g, test temperature: 30 ° C. Up to 30 cycles under the following conditions. The results are shown in FIG.

  From FIG. 10, the product obtained in Example 4 has an initial charge capacity of 209 mAh / g, an initial discharge capacity of 153 mAh / g, an initial charge / discharge efficiency of 73.2%, and an initial discharge average voltage of 3.55 V. It was found that the initial discharge energy density was 566 mWh / g, the discharge capacity after 30 cycles was 126 mAh / g, and the discharge capacity retention ratio after 30 cycles was 82.4%.

[Example 5]
Preparation of sample Weigh nickel (II) hexahydrate and manganese (II) tetrahydrate tetrahydrate to a molar ratio of 7: 3 (0.25 mol / batch), and dissolve in 500 ml of distilled water, An aqueous solution of metal salt was prepared. Next, 500 ml of distilled water was added to another container containing 50 g of sodium hydroxide to completely dissolve it, and kept at 20 ° C. in a thermostat. The aqueous solution of metal salt prepared above was gradually added dropwise over about 3 hours to an aqueous solution of sodium hydroxide to prepare a coprecipitate. Thereafter, the precipitate was matured by bubbling the coprecipitate for 2 days at room temperature using an oxygen gas generator. After aging, the precipitate was washed with water and filtered to obtain a raw material for firing.

  20.98 g (0.50 mol) of lithium hydroxide monohydrate was added to 200 ml of distilled water and completely dissolved. The raw material for baking prepared above was added to the said lithium hydroxide solution, and it was made to disperse | distribute and stir the mixer. The resulting mixture was transferred to a polytetrafluoroethylene petri dish, and the petri dish was placed in a dryer kept at 50 ° C., and was dried for 2 days. The obtained dry powder was pulverized and mixed, heated to 500 ° C. in an oxygen stream for 1 hour in an electric furnace, and sintered for 20 hours, and then cooled to around room temperature in a furnace to obtain a calcined product . After the obtained fired product is crushed, the temperature is raised again to 750 ° C. in an oxygen stream for 1 hour in an electric furnace, and firing is performed for 20 hours, and then cooled to around room temperature in the furnace to obtain a fired product. The The product was washed with distilled water, filtered and dried at 100 ° C. to obtain a product.

Evaluation by X-ray Diffraction The actual (+) and calculated (solid line) X-ray diffraction patterns of the product obtained above are shown in FIG. In the upper right part of FIG. 11, the diffraction angle 2θ is an enlarged view of around 17 to 32 °. Further, Rietveld analysis showed that the obtained product was monoclinic Li ₂ MnO ₃ single phase having a layered rock salt type structure. In addition, the monoclinic crystal phase of the product was confirmed by the presence of a small superlattice peak in the range of the diffraction angle 2θ of 20 to 30 °, as shown in the upper right part of FIG. . Furthermore, according to Rietveld analysis, the lattice constant a is 4.9425 (5) Å, the lattice constant b is 8.5751 (6) Å, the lattice constant c is 5.0099 (3) Å, and β is 109.220 (9 ), Lattice volume 200.5 (6) Å ³ , Ni and Mn ion occupancy in the Ni layer 79.2 (4)%, Ni and Mn ion occupancy in the Li layer 2.52 (7 It turned out that it is%.

Evaluation of charge and discharge characteristics After mixing 5 mg of the product obtained above with 5 mg of acetylene black, a positive electrode mixture is prepared using 0.5 mg of polytetrafluoroethylene, and the positive electrode mixture is pressure bonded to an aluminum mesh to obtain a positive electrode. And Subsequently, a coin-type battery was produced using the positive electrode, metal lithium as the negative electrode, 1 M LiPF ₆ / EC + DMC system as the electrolytic solution, and a separator, and the charge and discharge test was performed. The charge / discharge test was conducted at the start of charge up to 50 cycles under the conditions of a potential range of 2.2 to 4.8 V, a current density per positive electrode active material: 40 mA / g, and a test temperature of 30 ° C. The results are shown in FIG.

  From FIG. 12, the product obtained in Example 5 has an initial charge capacity of 162 mAh / g, an initial discharge capacity of 125 mAh / g, an initial charge / discharge efficiency of 77.2%, and an average initial discharge voltage of 3.73 V. It was found that the initial discharge energy density was 469 mWh / g, the discharge capacity after 50 cycles was 103 mAh / g, and the discharge capacity retention ratio after 50 cycles was 82.0%.

[Results and Discussion]
The results of evaluation of the samples of Examples 1 to 5 and Comparative Example 1 above by X-ray diffraction and the results of chemical analysis are shown in Table 1 below, and the results of charge / discharge characteristic evaluation are shown in Table 2 below.

  From the above results, the sample of Example 1 has almost the same initial charge / discharge capacity, initial discharge average voltage, and initial discharge energy density as compared with the sample of Comparative Example 1, and the initial charge / discharge efficiency, 50 cycles It was found that the later discharge capacity and the discharge capacity retention rate after 50 cycles were excellent.

  Further, although the samples of Examples 2 and 3 are slightly inferior in initial charge / discharge capacity, initial discharge average voltage, and initial discharge energy density as compared with the sample of Comparative Example 1, they are sufficient as positive electrode materials for lithium ion secondary batteries It was found that the level was usable, the initial charge / discharge efficiency was almost the same, and the discharge capacity after 50 cycles and the discharge capacity retention rate after 50 cycles were excellent.

  The sample of Example 4 is inferior to the sample of Comparative Example 1 in initial charge / discharge capacity, initial charge / discharge efficiency, initial discharge average voltage, and initial discharge energy density, but as a positive electrode material for lithium ion secondary batteries It was found to be a usable level and the discharge capacity retention rate after 30 cycles was excellent.

  The sample of Example 5 is inferior to the sample of Comparative Example 1 in initial charge / discharge capacity, initial charge / discharge efficiency, initial discharge average voltage, and initial discharge energy density, but as a positive electrode material for lithium ion secondary batteries It was found to be a usable level, and the discharge capacity retention rate after 50 cycles was excellent.

Claims (8)

General formula (1):
Li _x (Ni _1-y M _y ) O _{2 + δ} (1)
[Wherein, M represents at least one selected from the group consisting of Ge, Sn, Al, Co, and Mn. x, y and δ each represent 0.8 ≦ x ≦ 1.4, 0 <y ≦ 0.500, −0.20 ≦ δ ≦ 0.20. ]
A lithium nickel composite oxide represented by The lithium nickel composite oxide according to claim 1, wherein M is Ge, Sn, Al or Mn, or a combination of Al and Co. The lithium nickel-based composite oxide according to claim 1 or 2, comprising a crystal phase of a hexagonal layered rock salt type structure or a crystal phase of a monoclinic layered rock salt type structure. The lithium nickel-based composite oxide according to claim 3, which is composed only of a crystal phase of a hexagonal layered rock salt type structure or a crystal phase of a monoclinic layered rock salt type structure. It is a manufacturing method of lithium nickel type complex oxide in any one of Claims 1-4, Comprising:
A first step of mixing a lithium compound, a metal M compound, and nickel hydroxide and / or a water-soluble nickel salt in an aqueous solvent, and firing the mixture obtained in the first step under an oxidizing atmosphere A manufacturing method comprising a second step. The manufacturing method according to claim 5, wherein the first step is a step of adding a metal M compound and nickel hydroxide and / or a water-soluble nickel salt to an aqueous solution containing a lithium compound. The positive electrode material for lithium ion secondary batteries containing the lithium nickel type complex oxide in any one of Claims 1-4. A lithium ion secondary battery comprising the positive electrode material for a lithium ion secondary battery according to claim 7.

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