JP2006054159A - Anode active material for non-aqueous secondary battery, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium nickel complex oxide suitable for a positive electrode active material for a lithium ion secondary battery, which is low in reaction characteristics to an electrolytic solution, low in internal electric resistance when used as a battery, and strong against pressure in molding. <P>SOLUTION: A composition is expressed by a following general formula Li<SB>x</SB>Ni<SB>1-p-q-r</SB>Co<SB>p</SB>Al<SB>q</SB>A<SB>r</SB>O<SB>2-y</SB>(in the formula, a range of values of x, p, q, and y are 0.8≤x≤1.3, 0<p≤0.2, 0<q≤0.1, 0≤r≤0.1, -0.3<y<0.1, and A in the formula shows at least one kind of element chosen from a group composed of Ti, V, In, Cr, Fe, Sn, Cu, Zn, Mn, Mg, Ga, Ni, Co, Zr, Bi, Ge, Nb, Ta, Be, Ca, Sr, Ba, and Sc), and composed of primary particles which is a single crystal and of which the average particle diameter is 2 to 8 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a positive electrode active material for a lithium ion secondary battery and a method for producing the same, and more particularly to a positive electrode active material using a lithium nickel composite oxide and a method for producing the same.

As a positive electrode active material used for a lithium ion secondary battery, LiCoO ₂ mainly composed of cobalt is a typical material. However, cobalt is expensive because it has a small reserve, and supply is also unstable. For this reason, a shift to a positive electrode active material mainly composed of nickel or manganese is in progress. Among these materials, manganese-based materials are excellent in safety, but their capacity is very small compared to other materials and their cycle characteristics indicating their lifetime are very short, so that it is difficult to use them for large batteries. For this reason, studies on a positive electrode active material mainly composed of nickel are in progress.

  When lithium nickel composite oxide, which is a positive electrode active material mainly composed of nickel, is used as a positive electrode active material for a secondary battery, lithium ions are desorbed from the lithium nickelate crystal structure, and lithium nickelate Charging / discharging is performed by being inserted into the crystal structure.

  In general, pure lithium nickelate, in which nickel atoms are not substituted with other metal elements, has a sharp crystal structure phase transition due to volume change associated with the charge / discharge cycle. A large gap may be generated.

  Also, pure lithium nickelate has a problem in the thermal stability of the battery. In particular, when overcharged, extremely intense heat generation occurs instantaneously at around 210 ° C. When lithium ions are desorbed from the lithium nickelate crystal structure, the crystal structure becomes unstable. However, when further heat energy is applied, the crystal structure collapses, oxygen is released, and the electrolyte is rapidly oxidized and decomposed. It is thought that the cause is to proceed.

  These problems are all caused by the instability of the crystal structure, but it is necessary to make solid solution by replacing cobalt, which is effective in preventing phase transition, and aluminum, which is effective in stabilizing the crystal structure, with a part of nickel. (See Non-Patent Document 1). Therefore, at present, cobalt and aluminum are regarded as essential elements in the positive electrode active material mainly composed of nickel. Therefore, development of a highly safe positive electrode active material in which cobalt and aluminum are solid-dissolved among positive electrode active materials mainly composed of nickel is being actively performed.

Examples of the positive electrode active material mainly composed of nickel include lithium-nickel composite oxides mainly composed of lithium and nickel represented by LiNiO ₂ . As its form, the primary particles are monodispersed powder without forming secondary particles, or the primary particles are aggregated and formed into secondary particles having voids There is. However, in any form, the primary particle diameter is as small as an average particle diameter of about 1 μm or less, and thus the specific surface area is large.

  In a secondary battery using a lithium nickel composite oxide having a small primary particle size as a positive electrode active material, the area where the positive electrode active material comes into contact with the electrolytic solution is large, and lithium ions can be easily inserted and desorbed. For this reason, when lithium nickel composite oxide with a small primary particle diameter is used as the positive electrode active material, it is considered that the ability to flow a high load current, cycle characteristics, and output characteristics are improved.

  However, in reality, when a lithium nickel composite oxide with a small primary particle size is used, the active particle surface that is the interface between the electrolyte and the solid phase increases, so that contact with the electrolyte causes alteration of the electrolyte on the particle surface. A large amount of film may be generated to increase the electric resistance inside the battery, or the electric resistance inside the battery may increase due to the large number of contact surfaces between the primary particles.

  Furthermore, the secondary nickel-nickel composite oxide, which is an aggregate of primary particles, has a problem that it is weak against press pressure. For this reason, there is also a problem that the particle shape collapses at the time of forming by the roll press at the time of electrode production, a large number of isolated particles having poor conductivity without contact with the conductive material are generated, and the battery performance is lowered. In addition, secondary particles may collapse due to volume changes accompanying charging and discharging.

  In the case of a monodispersed powder of primary particles less than 1 μm, although there are no grain boundaries inside the particles, the active reaction area is secondary aggregate because almost the entire surface of the primary particles is in contact with the electrolyte. Larger and more altered films are generated. For this reason, electrical resistance rises more than the secondary aggregate, and high output and long life cannot be obtained. Furthermore, the filling property at the time of electrode preparation also deteriorates.

  For this reason, it has been considered difficult to improve the output characteristics and cycle characteristics of the lithium ion secondary battery.

  As a method for solving this problem, it is conceivable to reduce the active surface area and the number of crystal grain boundaries. For this purpose, it is conceivable as one method to grow particles larger than before.

  As described in Patent Document 1, the primary particle size of the nickel compound can be increased by heating and growing the particles during the production of the nickel compound. However, the method described in Patent Document 1 is a method in the case of not containing aluminum, and the lithium nickel composite oxide produced thereby has very poor thermal stability, and there is a risk of heat generation, ignition, and explosion. Therefore, it is indispensable that the lithium nickel composite oxide contains Al.

  However, in the presence of aluminum, the primary particle size hardly grows to less than 1 μm even with the method described in Patent Document 1 or the method of performing heat treatment at high temperature.

Japanese Patent Laid-Open No. 11-1324

The 43rd Battery Symposium Performance Summary (Fukuoka) 1A04 (2002)

  In order to achieve higher output and longer life of lithium ion secondary batteries using lithium nickel composite oxide as the positive electrode active material, a large amount of film is formed by reaction with the electrolyte on the surface of lithium nickel composite oxide particles. The problem that the electric resistance inside the battery increases, the problem that the electric resistance inside the battery increases due to the large number of contact surfaces between the primary particles, and the conventional method. In the obtained secondary particle body, it is necessary to solve the problem that the shape of the particles collapses due to the molding by the roll press at the time of producing the electrode, and the isolated particles having poor conductivity are generated.

  The present invention has been made in view of such problems, and has low reactivity with an electrolytic solution, low internal electrical resistance when used as a battery, and is also strong against pressure during molding. An object is to provide a lithium nickel composite oxide.

  The positive electrode active material for a non-aqueous secondary battery according to the first invention is a positive electrode active material for a non-aqueous secondary battery mainly composed of nickel and lithium, the composition is represented by the following chemical formula 1, and It consists of primary particles which are single crystals and have an average particle diameter of 2 to 8 μm.

  However, the ranges of the values of x, p, q, r, and y in Chemical Formula 1 are 0.8 ≦ x ≦ 1.3, 0 <p ≦ 0.2, 0 <q ≦ 0.1, and 0 ≦ r. ≦ 0.1, −0.3 <y <0.1, and A in chemical formula 1 is Ti, V, In, Cr, Fe, Sn, Cu, Zn, Mn, Mg, Ga, Ni, Co And at least one element selected from the group consisting of Zr, Bi, Ge, Nb, Ta, Be, Ca, Sr, Ba, and Sc.

  The method for producing a positive electrode active material for a non-aqueous secondary battery according to the first invention includes a step of obtaining a nickel compound containing cobalt from a nickel compound and a cobalt compound, and the nickel compound containing cobalt in the compound. Inorganic chloride or inorganic chloride oxide is added so that the number of moles of chlorine is in the range of 0.1 to 15% with respect to the total number of moles of nickel and cobalt. A step of obtaining an oxide composed of a single crystal having an average particle size of 2 to 8 μm by baking the mixture at a temperature of 800 to 1300 ° C., and an aluminum compound and a lithium compound mixed with the oxide Or a step of obtaining a mixture by coating the surface of the oxide with an aluminum compound and then mixing a lithium compound, and firing the mixture at 600 to 800 ° C. Wherein the step of obtaining a lithium-nickel composite oxide, in that it consists of.

  The inorganic chloride or inorganic chloride oxide is Ti, V, In, Cr, Fe, Sn, Cu, Zn, Mn, Mg, Ga, Ni, Co, Zr, Bi, Ge, Nb, Ta, Be, Ca. It is preferably a chloride or chloride oxide of at least one element selected from the group consisting of Sr, Ba and Sc.

  The positive electrode active material for a non-aqueous secondary battery according to the second invention is a positive electrode active material for a non-aqueous secondary battery mainly composed of nickel and lithium, and the composition is represented by the following chemical formula 2; It consists of primary particles which are single crystals and have an average particle diameter of 2 to 12 μm.

  However, the ranges of the values of x, p, q, r, and y in the formula are 0.8 ≦ x ≦ 1.3, 0 <p ≦ 0.2, 0 <q ≦ 0.1, 0 <r ≦ 0.05, -0.3 <y <0.1.

  The method for producing a positive electrode active material for a non-aqueous secondary battery according to the second invention includes a step of obtaining a nickel compound containing cobalt and aluminum from a nickel compound, a cobalt compound, and an aluminum compound, or cobalt from a nickel compound and a cobalt compound. And obtaining a cobalt-containing nickel compound coated with an aluminum compound by coating the surface of the nickel compound with an aluminum compound, and the compound containing nickel as a main component. Adding vanadium chloride and mixing the mixture so that the number of moles of chlorine is in the range of 0.5 to 15% with respect to the total number of moles of nickel, cobalt, and aluminum; and A process of roasting at 900 to 1300 ° C. to make an oxide, Obtaining a mixture composed mainly of lithium nickel mixed beam compound was firing the mixture at 600 to 800 ° C., for obtaining a lithium-nickel composite oxide, characterized in that it consists.

  In the method for producing a positive electrode active material for a non-aqueous secondary battery according to the first invention and the second invention, the nickel compound (a nickel compound containing cobalt in the first invention, cobalt and aluminum in the second invention) The nickel compound) comprises, for example, at least one of hydroxide, oxyhydroxide and carbonate, and the aluminum compound includes, for example, hydroxide, oxyhydroxide, oxide, sulfuric acid The lithium compound comprises at least one of a salt and an aluminate, and the lithium compound is, for example, hydroxide, oxyhydroxide, oxide, carbonate, sulfate, nitrate, dicarboxylate, fatty acid salt, citric acid It consists of at least one of a salt, an alkyl compound, and a halogen compound.

  The positive electrode active material for a non-aqueous secondary battery containing nickel and lithium as main components according to the present invention is a single crystal and contains an average particle size of 2 to 8 μm, particularly vanadium, while containing aluminum. In the case of using the manufacturing method, since it consists of primary particles grown to 2 to 12 μm, the reactivity with the electrolytic solution is low, the internal electrical resistance when used as a battery is low, and the pressure during molding Also strong. For this reason, when the positive electrode active material for a non-aqueous secondary battery according to the present invention is used in a lithium ion secondary battery, the output and life can be improved.

In the method for producing a positive electrode active material for a non-aqueous secondary battery according to the first invention, a nickel compound containing cobalt can be effectively grown by baking it before adding aluminum.
In the method for producing a positive electrode active material for a non-aqueous secondary battery according to the second invention, vanadium chloride (VCl ₃ ) is used. At both times during firing for introducing lithium, a compound containing nickel as a main component undergoes grain growth, so that a highly functional material can be produced at low cost without complicating the process.

[1. Positive electrode active material for secondary battery according to the first invention and method for producing the same]
In order to solve the above-described problems, the present inventor conducted intensive test research, and as a result, the primary particles of the lithium-nickel composite oxide were formed into a single crystal having an average particle diameter of 2 to 8 μm. The inventors have obtained knowledge that the reactivity between the particles and the electrolyte solution on the surface of the lithium composite oxide particles, the internal resistance due to the large number of contact surfaces between the primary particles, and the deformation of the particles caused by press molding can be solved.

  In addition, the inventor has also conducted experimental research to establish a production technique for stably obtaining a single crystal having an average particle diameter of 2 to 8 μm as primary particles of lithium nickel composite oxide containing aluminum. . As a result, a nickel compound containing cobalt is produced from a nickel compound and a cobalt compound, and a predetermined amount of inorganic chloride or inorganic chloride oxide is added thereto, followed by roasting at a predetermined temperature to greatly grow grains. Thus, it was found that primary particles of lithium nickel composite oxide having a single crystal and an average particle diameter of 2 to 8 μm can be stably obtained.

  Hereinafter, the reason for the numerical limitation in each constituent requirement of the positive electrode active material for a secondary battery according to the first invention and the manufacturing method thereof will be described.

“Primary particles with a single crystal and an average particle size of 2-8 μm”
By using a single crystal, there is no crystal grain boundary in the primary particles, and the electrical resistance can be reduced. The reason why the average particle diameter is 2 to 8 μm is that when the average particle size is smaller than 2 μm, the surface area in contact with the electrolytic solution is increased, and a large number of coatings that are altered by the reaction between the electrolytic solution and the particles are formed. On the other hand, when the average particle size grows to about 12 μm, the battery characteristics are improved. However, when the average particle diameter is larger than 12 μm, the Li ion movement speed in the crystal becomes rate-determined, and the load current characteristics decrease. However, in the first invention, it is difficult to grow the grains so that the average particle diameter is 8 μm or more.

In addition, since the primary particles of the single crystal are monodispersed and do not constitute secondary particles, the shape of the particles is not easily collapsed even when there is a volume change due to compression force or charging / discharging, for example, Even when a press pressure of 3 ton / cm ² is applied, the particle shape does not collapse.

  Furthermore, the measurement result of the tap density is 2.0 g / cc or more, and the filling property is also good. This numerical value is comparable to the conventional one that forms spherical secondary particles.

  Therefore, by satisfying this configuration requirement, when used as a positive electrode active material for a secondary battery, a high output and a long life of the secondary battery are possible.

_{"Li x Ni 1-pqr Co p} Al q A r O 2-y
However, 0.8 ≦ x ≦ 1.3, 0 <p ≦ 0.2, 0 <q ≦ 0.1, 0 ≦ r ≦ 0.1, −0.3 <y <0.1. , A is from Ti, V, In, Cr, Fe, Sn, Cu, Zn, Mn, Mg, Ga, Ni, Co, Zr, Bi, Ge, Nb, Ta, Be, Ca, Sr, Ba, Sc. At least one element selected from the group consisting of: "
p, q, and r indicate the amount of substitution of Co, Al, and A with respect to Ni, and when the number of Ni atoms when not substituted at all is 1, the atoms of Co, Al, and A that replace Ni The numbers are p, q and r, respectively.

  The ranges of p and q are preferably 0 <p ≦ 0.2 and 0 <q ≦ 0.1, more preferably 0.1 ≦ p ≦ 0.2 and 0.02 ≦ q ≦ 0.05. A range of is desirable. This is because if both Co and Al are too small, the effect of addition is reduced, the problem of cycle life and thermal stability is not solved, and if it is too large, the battery capacity is lowered, and the capacity is higher than other lithium transition metal oxides. This is because there is no advantage of being.

  x represents the amount of Li contained, and the range of x is preferably in the range of 0.8 ≦ x ≦ 1.3. If the value of x is less than 0.8, the amount of lithium in the lithium nickel composite oxide is insufficient, and the capacity of the battery is reduced. If it exceeds 1.3, excess Li remains as lithium carbonate on the powder surface, In addition to inhibiting lithium ion insertion and desorption, excess Li enters the lattice defects in the layered structure consisting of Ni and O, reducing the migration of lithium ions during charge and discharge and inhibiting diffusion in the solid phase. This is because the battery capacity and cycle life are greatly reduced.

  r represents the content of the metal element A, and the metal element A is Ti, V, In, Cr, Fe, Sn, Cu, Zn, Mn, Mg, Ga, Ni, Co, Zr, Bi, Ge. , Nb, Ta, Be, Ca, Sr, Ba, Sc. At least one element selected from the group consisting of Nb, Ta, Be, Ca, Sr, Ba, and Sc. The reason why the metal element A is limited to the metal element is that it has an effect of promoting sintering during firing, battery characteristics, and safety. The range of r is preferably in the range of 0 ≦ r ≦ 0.1. This is because if the value of r exceeds 0.1, the solid solution limit will be exceeded, or the battery capacity will be greatly reduced.

  y represents an oxygen deficiency amount or an oxygen excess amount. The range of y is preferably in the range of −0.3 <y <0.1. This is because if the value of y is not within this range, the amount of oxygen deficiency or excess amount of oxygen becomes excessive, and the crystal structure impairs reversibility during strain charge / discharge.

“Method for Producing Lithium Nickel Composite Oxide with Co and Al Solid Solution According to the First Invention”
Various methods are conceivable as a method for producing a lithium nickel composite oxide in which Co and Al are dissolved in the first invention. For example, a nickel compound containing a metal element other than Li (Co, Al) is obtained by crystallization, etc., and a method in which a lithium compound is mixed and fired, or a solution containing a required metal element A method of spraying the mixed liquid and performing a thermal decomposition treatment, a method of pulverizing and mixing all the metal element compounds required by mechanical pulverization using a ball mill, and the like, followed by firing, can be considered.

  However, in any method, the growth of primary particles is remarkably suppressed in the presence of Al, and it is very difficult to obtain an average particle size of 1 μm or more. This is because Al inhibits the growth of nickel oxide crystal grains.

  In contrast, in the present invention, heat treatment is performed in a state in which Al is not yet contained, and nickel oxide crystal grains in which Co is dissolved are grown, and then an aluminum compound and a lithium compound are added. There is a feature, and by this method, it is possible to produce a lithium nickel composite oxide in which Co and Al are solid-solved, in which the average particle size is grown to 2 to 8 μm.

  Hereinafter, the manufacturing method according to the first invention will be described in more detail.

The heat treatment (roasting) temperature for grain growth needs to be 800 ° C. or higher. This is because the primary particles have a particle size of 1 μm or more. However, if the temperature exceeds 1300 ° C., the sintering proceeds rapidly, and the voids in the Ni oxide particles in which Co is diffused in the solid phase become very small. As a result, even if Ni oxide particles are subsequently reacted with a lithium compound, the surface area of the Ni oxide particles is so small that the Li compound cannot react sufficiently, and LiO or Li ₂ CO _{3 is} formed on the particle surface. It will remain. For this reason, the heat treatment (roasting) temperature for grain growth is preferably in the range of 800 to 1300 ° C, more preferably in the range of 900 to 1100 ° C.

  However, by merely firing a nickel compound containing the necessary metal elements excluding Al and Li in this heat treatment temperature range, the grain size can be grown only to about 2 μm.

  On the other hand, in the present invention, in order to further promote the grain growth, an inorganic chloride or an inorganic chloride oxide is added as a liquid or solid, and this is another feature of the present invention. Numerically, the number of moles of chlorine is in the range of 0.1 to 15% with respect to the total number of moles of metal elements in the compound containing nickel as the main component (number of moles of Ni + number of moles of Co). More preferably 1.0 to 10%. If it is less than 0.1%, no matter what inorganic chloride or inorganic chloride oxide is used, the effect of grain growth is not seen compared to the case of no addition. If it exceeds 15%, the diffusion limit of the inorganic chloride or inorganic chloride oxide in the nickel oxide crystal will be exceeded, and a lithium-nickel composite oxide layer with high Cl content will be formed on the surface layer. To do. Further, even if inorganic chloride or inorganic chloride oxide is further added, grain growth reaches the limit and no change is observed.

  Inorganic chlorides or inorganic chlorides for adding Cl include Ti, V, In, Cr, Fe, Sn, Cu, Zn, Mn, Mg, Ga, Ni, Co, Zr, Bi, Ge, and Nb. An inorganic chloride or an inorganic chloride oxide composed of at least one element selected from the group consisting of Ta, Be, Ca, Sr, Ba and Sc. When a chloride composed of an alkali metal element is used, grain growth occurs, but the lithium site in the crystal is replaced by alkali metal, so that the capacity of the battery is extremely reduced. In the case of using chlorides composed of elements of 3B-6B group, it does not contribute to the grain growth only by solid solution / diffusion inside the nickel compound particles or changing to single oxide etc. There is a problem that it ends up.

  The thus obtained grain-grown nickel composite oxide is reacted by adding an Al and Li compound to obtain a target lithium-nickel composite oxide (single crystal having an average particle size of 2). ˜8 μm) can be obtained. Specifically, the following method can be considered. One is that the surface of the nickel composite oxide is coated with a compound containing aluminum (chemical precipitation represented by crystallization, mechanical implantation represented by mechanochemical, etc.), and then mixed with a lithium compound. It is a method of baking. The other is a method in which the nickel composite oxide, an aluminum compound, and a lithium compound are mixed and fired.

  In such a method, the mixing with the lithium compound is performed so as to obtain a desired composition by a dry mixer such as a V blender or a mixing granulator. Thereafter, firing is performed in an electric furnace, kiln, tubular furnace, pusher furnace or the like in an oxygen atmosphere or a dry air atmosphere subjected to dehumidification and carbonation treatment.

  At this time, the firing temperature is preferably in the range of 600 to 800 ° C, more preferably in the range of 700 to 780 ° C. This is because lithium nickelate is produced if heat treatment is performed at a temperature lower than 600 ° C. or higher than 500 ° C., but the crystal is undeveloped and structurally unstable, and the structure is easily formed by phase transition due to charge / discharge. Because it will be destroyed. In addition, when the temperature exceeds 800 ° C., the layered structure collapses, resulting in lithium nickelate that cannot insert and desorb lithium ions, which is important for lithium ion secondary batteries, and nickel composite oxide is decomposed to generate nickel oxide and the like. It is because it ends.

  As the compound used in the above steps, the following can be used. As the nickel compound containing necessary metal elements excluding Al and Li, those selected from hydroxides, oxyhydroxides and carbonates can be used. As the aluminum compound to be coated or mixed, one selected from hydroxide, oxyhydroxide, oxide, sulfate and aluminate can be used. As the lithium compound, at least one selected from hydroxide, oxyhydroxide, oxide, carbonate, sulfate, nitrate, dicarboxylate, fatty acid salt, citrate, alkyl compound, and halogen compound is used. be able to.

[2. Positive electrode active material for secondary battery according to the second invention and method for producing the same]
In the manufacturing method according to the first invention, heat treatment is performed in a state where Al is not yet contained, and nickel oxide crystal grains in which Co is dissolved are grown, and then an aluminum compound and a lithium compound are added. Thus, a lithium nickel composite oxide in which Co and Al are dissolved in an average particle diameter of 2 to 8 μm is manufactured, but the present inventor grows crystal grains even when heat treatment is performed in a state in which Al is contained. Further studies were conducted to see if this could be done.

As a result, by adding and mixing a predetermined amount of vanadium chloride (VCl ₃ ), by performing heat treatment in a state of containing Al, Co having grown into an average particle diameter of 2 to 12 μm in a single crystal, The present inventors have obtained knowledge that a lithium nickel composite oxide in which Al is dissolved can be stably produced. Specifically, a nickel compound containing Co and Al is produced from a nickel salt, a cobalt salt, and an aluminum salt, a predetermined amount of VCl ₃ is added to the nickel compound, roasted at a predetermined temperature, and then a lithium compound. And firing at a predetermined temperature, the grains can be greatly grown, and primary particles of lithium nickel composite oxide having a particle size of 2 to 12 μm can be stably obtained.

  The constituent requirements of the positive electrode active material for a secondary battery according to the second invention are the same as those of the first invention, but in the second invention, a single crystal having an average particle diameter of 12 μm is obtained.

"Method for producing lithium nickel composite oxide in which Co and Al are dissolved"
In the second invention, by adding a predetermined amount of VCl ₃ and baking, nickel oxide grains are grown even if Al is present, and then a predetermined amount of lithium compound is mixed with the grown nickel oxide. Thus, a lithium nickel composite oxide in which Co and Al having a particle diameter of 2 to 12 μm are finally dissolved is obtained. The reason why nickel oxide grows even when Al is present by adding VCl ₃ and baking is because the ionic valence of V is likely to fluctuate. This is probably because the structure becomes unstable as a result of which the nickel oxide grains grow even in the presence of Al.

  Hereinafter, the production method according to the second invention will be described in more detail.

The heat treatment temperature for grain growth needs to be 900 ° C. or higher. This is because the primary particles have a particle size of 1 μm or more. However, if the temperature exceeds 1300 ° C., the sintering proceeds rapidly, and the voids in the Ni oxide particles in which Co and Al diffuse in the solid phase become very small. As a result, even if Ni oxide particles are subsequently reacted with a lithium compound, the surface area of the Ni oxide particles is so small that the Li compound cannot react sufficiently, and LiO or Li ₂ CO _{3 is} formed on the particle surface. It will remain. For this reason, the heat treatment temperature for grain growth is preferably in the range of 900 to 1300 ° C, more preferably in the range of 900 to 1100 ° C.

  However, only the submicron order grain growth can be expected by simply roasting a nickel compound containing necessary metal elements (Co, Al) other than Li in this heat treatment temperature range. The primary particle diameter is 1 μm at the maximum.

In contrast, the second invention is characterized in that VCl ₃ is added as a liquid or solid when roasting a nickel compound containing Co and Al in order to promote grain growth. Numerically, the number of moles of chlorine is in the range of 0.5 to 15% with respect to the total number of moles of metal elements in the compound containing Ni as the main component (number of moles of Ni + number of moles of Co + number of moles of Al). It is necessary to be such that 1.0 to 10% is desirable. If it is less than 0.5%, the effect of grain growth is not seen even when VCl ₃ is used compared to the case of no addition. If it exceeds 15%, the diffusion limit of VCl _{3 in} the nickel oxide crystal will be exceeded, and a lithium nickel composite oxide layer having a high concentration of Cl or V will be formed on the surface layer.

  The target lithium nickel composite oxide (single crystal, average particle diameter of 2 to 12 μm) can be obtained by adding a lithium compound to the nickel composite oxide thus obtained and reacting it. it can. Specifically, the nickel oxide and the lithium compound are baked after dry mixing.

  In such a method, the mixing with the lithium compound is performed so as to obtain a desired composition by a dry mixer such as a V blender or a mixing granulator. Thereafter, firing is performed in an electric furnace, kiln, tubular furnace, pusher furnace or the like in an oxygen atmosphere or a dry air atmosphere subjected to dehumidification and carbonation treatment.

  At this time, the firing temperature is preferably in the range of 600 to 800 ° C, more preferably in the range of 700 to 780 ° C. This is because lithium nickelate is produced if heat treatment is performed at a temperature lower than 600 ° C. or higher than 500 ° C., but the crystal is undeveloped and structurally unstable, and the structure is easily formed by phase transition due to charge / discharge. It will be destroyed. In addition, when the temperature exceeds 800 ° C., the layered structure collapses, resulting in lithium nickelate that cannot insert and desorb lithium ions, which is important for lithium ion secondary batteries, and nickel composite oxide is decomposed to generate nickel oxide and the like. It is because it ends.

  The following compounds can be used as compounds used in the above steps. As the nickel compound containing the necessary metal elements (Co, Al) excluding Li, those selected from hydroxides, oxyhydroxides, and carbonates can be used. Further, when Al is contained by coating a nickel compound containing Co with an aluminum compound, the aluminum compound is selected from hydroxide, oxyhydroxide, oxide, sulfate, and aluminate. Things can be used. As the lithium compound, at least one selected from hydroxide, oxyhydroxide, oxide, carbonate, sulfate, nitrate, dicarboxylate, fatty acid salt, citrate, alkyl compound, and halogen compound is used. be able to.

  Examples 1 to 6 are examples according to the first invention, and Examples 7 to 10 are examples according to the second invention. Comparative Examples 1 to 4 are comparative examples corresponding to the first invention, and Comparative Examples 5 to 8 are comparative examples corresponding to the second invention.

"Examples 1-6, Comparative Examples 1-4"
Example 1
Nickel sulfate hexahydrate (manufactured by Wako Pure Chemical Industries) and cobalt sulfate heptahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed at a desired ratio to prepare an aqueous solution. This aqueous solution was dropped into an agitated reaction tank with a discharge port with water kept at 50 ° C. simultaneously with aqueous ammonia (manufactured by Wako Pure Chemical Industries) and aqueous caustic soda (manufactured by Wako Pure Chemical Industries). The pH was maintained at 11.5 and the residence time was controlled to be 11 hours. In this way, spherical nickel hydroxide containing cobalt was produced by a reactive crystallization method. The nickel hydroxide was spherical secondary particles in which primary particles were aggregated.

With respect to the total number of moles of metal elements in the obtained cobalt-containing nickel hydroxide (number of moles of Ni + number of moles of Co), the number of moles of Cl in the cobalt-containing nickel hydroxide is 2.5%. Calcium chloride (CaCl ₂ ) (manufactured by Wako Pure Chemical Industries) was calculated and weighed. The weighed calcium chloride powder was dissolved in pure water, but the amount of pure water was such that it did not become a paste even when the calcium chloride powder was dissolved. The obtained calcium chloride aqueous solution was uniformly sprayed and mixed with cobalt-containing nickel hydroxide. The mixed powder is roasted at 1000 ° C. to form an oxide, and then the oxide is mixed with aluminum hydroxide (Wako Pure Chemical) and lithium hydroxide monohydrate (Wako Pure Chemical) with a desired composition. It mixed with the V blender so that it might become. The mixture was calcined in an electric furnace in an oxygen atmosphere at a time of 3 hours and at a temperature of 500 ° C., then fired at a time of 20 hours and a temperature of 730 ° C., and then cooled to room temperature. did. After furnace cooling, a monodispersed lithium nickel composite oxide of primary particles was produced by pulverization.

  It was confirmed by JEOL scanning electron microscope “JSM-5510” that the obtained primary particles were single crystals. At this time, the average particle diameter of the primary particles was 4.5 μm. FIG. 1 shows an SEM photograph of the obtained primary particles.

Each mass of the raw material used in the above process is such that the molar ratio of each element in the lithium nickel composite oxide as the final target product is Ni: Co: Al: Li = 0.82: 0.15: 0. 03: Weighed to 1.05. As a result, the chemical composition of the lithium nickel composite oxide was Li _1.048 Ni _0.808 Co _0.150 Al _0.032 Ca _0.01 O _2.12 .

2.0 g of the obtained lithium nickel composite oxide was sampled, loaded into a jig for compaction treatment, and pressurized to 3.0 ton / cm ² with an Amsler type hydraulic compression tester. A test (hereinafter referred to as “pressure test”) was conducted to confirm whether or not the particles constituting the oxide powder were damaged. The pressure test is a test that assumes molding by a roll press at the time of electrode production, and that the particles constituting the lithium nickel composite oxide powder do not break even after molding by the roll press at the time of electrode production. This is a test to confirm.

When a pressure of 3.0 ton / cm ² was applied to the lithium nickel composite oxide powder by the above-described method, the lithium nickel composite oxide powder was integrated into a pellet, but became a pellet. A part of the powder was observed with an SEM to examine whether or not the particles constituting the lithium nickel composite oxide powder were damaged. Specifically, 50 particles were randomly selected from the observed image, and the number of broken particles was counted. Table 1 shows the number of broken particles.

  Furthermore, using the obtained lithium nickel composite oxide, a battery was prepared as follows, and the charge / discharge capacity was measured.

First, 90% by mass of lithium nickel composite oxide as an active material powder was mixed with 5% by mass of acetylene black and 5% by mass of PVDF (polyvinylidene fluoride), and NMP (n-methylpyrrolidone) was added to make a paste. This was applied to a 20 μm thick aluminum foil. The coating amount was set so that the weight of the active material after drying was 0.05 g / cm ² . And it vacuum-dried at 120 degreeC, and it punched in the disk shape of diameter 1cm, and set it as the positive electrode. Lithium metal was used for the negative electrode, and an equivalent mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) using LiClO ₄ at a concentration of 1 M as a supporting salt was used for the electrolyte. A separator made of polyethylene was impregnated with this electrolytic solution, and a 2032 type coin battery as shown in FIG. 2 was produced in a glove box in an Ar atmosphere in which the dew point was controlled at −80 ° C.

  As shown in FIG. 2, in the produced 2032 type coin battery, a separator 2 impregnated with the electrolytic solution is disposed between a positive electrode 1 as an evaluation electrode and a negative electrode 3 made of lithium metal. The whole is covered with a negative electrode can 6 from the negative electrode side, and covered with a positive electrode can 5 from the positive electrode side. A gasket 4 is disposed between the positive electrode can 5 and the negative electrode can 6 to prevent the positive electrode can 5 and the negative electrode can 6 from being short-circuited and to shield the interior of the 2032 type coin battery 7 from the outside.

  The produced battery was left for about 24 hours, and after the OCV was stabilized, the initial discharge capacity, cycle characteristics, and output characteristics were measured.

  When examining the initial discharge capacity and cycle characteristics, a charge / discharge test was performed at a current density of 0.5 mA with respect to the positive electrode and a cut-off voltage of 4.3 to 3.0 V. The cycle characteristics were evaluated by calculating the ratio (capacity maintenance ratio) of the discharge capacity at the 20th cycle to the discharge capacity at the 1st cycle. Table 2 shows the results.

When examining the output characteristics, first, the current density with respect to the positive electrode was set to 0.1 mA / cm ² , and the battery was slowly charged until the SOC (State Of Charge) reached 40%. Then, the current density was changed to 3.0 mA / cm ² and charging and discharging were performed for 10 seconds. Then, the difference between the voltage value at SOC 40% and a discharge starting voltage at that time (V2) (V1), divided by the current value 3.0mA flowing through the current density or per positive electrode 1 cm ^2, per positive electrode 1 cm ² The gradient dV / dA of the flowing current and voltage was obtained (see the following formula 1). Then, using the value of the obtained gradient dV / dA, the current value (A1) per 1 cm ² of the positive electrode when the discharge start voltage dropped to 3.0 V was calculated by the following formula 2. A value obtained by multiplying the obtained current value A1 per 1 cm ^{2 of} the positive electrode by a discharge voltage of 3.0 V was calculated and evaluated as an output value (mW) per 1 cm ² of the positive electrode (see Formula 3 below). Table 2 shows the results.

(Example 2)
In Example 1, the number of moles of Cl in the cobalt-containing nickel hydroxide is 2.5% with respect to the total number of metal elements in the cobalt-containing nickel hydroxide (number of moles of Ni + number of moles of Co). Thus, the sample was prepared, but in Example 2, the sample was prepared to be 0.13%. Other conditions were the same as in Example 1. As a result, a lithium nickel composite oxide having an average particle size of 2.2 μm and a chemical composition of Li _1.048 Ni _0.815 Co _0.151 Al _0.033 Ca _0.001 O _2.08 was obtained. The chloride used to introduce Cl into the cobalt-containing nickel hydroxide is calcium chloride (CaCl ₂ ), which is the same as in Example 1.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 1 and 2, respectively.

(Example 3)
In Example 1, the number of moles of Cl in the cobalt-containing nickel hydroxide is 2.5% with respect to the total number of metal elements in the cobalt-containing nickel hydroxide (number of moles of Ni + number of moles of Co). Thus, the sample was prepared, but in Example 2, the sample was prepared to be 14.0%. The other conditions were the same as in Example 1. As a result, a lithium nickel composite oxide having an average particle diameter of 7.5 μm and a chemical composition of Li _1.051 Ni _0.777 Co _0.144 Al _0.031 Ca _0.048 O _2.03 was obtained. The chloride used to introduce Cl into the cobalt-containing nickel hydroxide is calcium chloride (CaCl ₂ ), which is the same as in Example 1.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 1 and 2, respectively.

Example 4
In this example, as in Example 1, the number of moles of Cl in the cobalt-containing nickel hydroxide is equal to the total number of moles of metal elements in the cobalt-containing nickel hydroxide (number of moles of Ni + number of moles of Co). The sample was prepared to 2.5%, but the chloride used to introduce Cl into the cobalt-containing nickel hydroxide was calcium chloride (CaCl ₂ ) in Example 1, whereas This example differs from Example 1 in that it is nickel chloride NiCl ₂ (manufactured by Wako Pure Chemical Industries). The other conditions were the same as in Example 1. As a result, a lithium nickel composite oxide having an average particle size of 3.7 μm and a chemical composition of Li _1.053 Ni _0.821 Co _0.150 Al _0.029 O _2.13 was obtained.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 1 and 2, respectively.

(Example 5)
In this example, as in Example 1, the number of moles of Cl in the cobalt-containing nickel hydroxide is equal to the total number of moles of metal elements in the cobalt-containing nickel hydroxide (number of moles of Ni + number of moles of Co). The sample was prepared to 2.5%, but the chloride used to introduce Cl into the cobalt-containing nickel hydroxide was calcium chloride (CaCl ₂ ) in Example 1, whereas This example is different from Example 1 in that it is cobalt chloride CoCl ₂ (manufactured by Wako Pure Chemical Industries). The other conditions were the same as in Example 1. As a result, a lithium nickel composite oxide having an average particle diameter of 3.8 μm and a chemical composition of Li _1.047 Ni _0.810 Co _0.159 Al _0.031 O _2.06 was obtained.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 1 and 2, respectively.

(Example 6)
In this example, as in Example 1, the number of moles of Cl in the cobalt-containing nickel hydroxide is equal to the total number of moles of metal elements in the cobalt-containing nickel hydroxide (number of moles of Ni + number of moles of Co). The sample was prepared to 2.5%, but the chloride used to introduce Cl into the cobalt-containing nickel hydroxide was calcium chloride (CaCl ₂ ) in Example 1, whereas This example is different from Example 1 in that it is manganese chloride MnCl ₂ (manufactured by Wako Pure Chemical Industries). The other conditions were the same as in Example 1. As a result, a lithium nickel composite oxide having an average particle size of 4.1 μm and a chemical composition of Li _1.048 Ni _0.806 Co _0.152 Al _0.029 Mn _0.013 O _2.08 was obtained.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 1 and 2, respectively.

(Comparative Example 1)
In Example 1, the number of moles of Cl in the cobalt-containing nickel hydroxide is 2.5% with respect to the total number of metal elements in the cobalt-containing nickel hydroxide (number of moles of Ni + number of moles of Co). Thus, although the sample was prepared, in Comparative Example 1, the sample was prepared to be 0.05%. The other conditions were the same as in Example 1. As a result, a lithium nickel composite oxide having an average particle size of 1.4 μm and a chemical composition of Li _1.050 Ni _0.815 Co _0.151 Al _0.033 Ca _0.0002 O _2.12 . The chloride used to introduce Cl into the cobalt-containing nickel hydroxide is calcium chloride (CaCl ₂ ), which is the same as in Example 1.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 1 and 2, respectively.

(Comparative Example 2)
In Example 1, the number of moles of Cl in the cobalt-containing nickel hydroxide is 2.5% with respect to the total number of metal elements in the cobalt-containing nickel hydroxide (number of moles of Ni + number of moles of Co). Thus, although the sample was prepared, in Comparative Example 2, the sample was prepared to be 17%. The other conditions were the same as in Example 1. As a result, a lithium nickel composite oxide having an average particle size of 7.8 μm and a chemical composition of Li _1.048 Ni _0.774 Co _0.143 Al _0.029 Ca _0.054 O _2.07 was obtained. The chloride used to introduce Cl into the cobalt-containing nickel hydroxide is calcium chloride (CaCl ₂ ), which is the same as in Example 1.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 1 and 2, respectively.

(Comparative Example 3)
In Examples 1 to 6, aluminum hydroxide was mixed after roasting a mixed powder of cobalt solid solution nickel hydroxide and calcium chloride at 1000 ° C., and in this comparative example, The point from which aluminum was added before baking at 1000 degreeC differs from Examples 1-6. Moreover, in this comparative example, unlike Examples 1-6, chlorine is not added.

  Hereinafter, a method for manufacturing the sample of Comparative Example 3 will be described.

  Nickel sulfate hexahydrate (manufactured by Wako Pure Chemical Industries), cobalt sulfate heptahydrate (manufactured by Wako Pure Chemical Industries), and aluminum sulfate (manufactured by Wako Pure Chemical Industries) were mixed in a desired ratio to prepare an aqueous solution. This aqueous solution was dropped into an agitated reaction tank with a discharge port with water kept at 50 ° C. simultaneously with aqueous ammonia (manufactured by Wako Pure Chemical Industries) and aqueous caustic soda (manufactured by Wako Pure Chemical Industries). The pH was kept at 11.5 and the residence time was controlled to be 11 hours. Thus, spherical nickel hydroxide containing cobalt was produced by a reactive crystallization method. The nickel hydroxide was spherical secondary particles in which primary particles were aggregated.

  This powder was roasted at 1000 ° C. to form an oxide, and then mixed with lithium hydroxide monohydrate (manufactured by Wako Pure Chemical Industries) in a V blender so as to have a desired composition. The mixture was calcined in an electric furnace in an oxygen atmosphere at a time of 3 hours and at a temperature of 500 ° C., then fired at a time of 20 hours and a temperature of 730 ° C., and then cooled to room temperature. Thus, a lithium nickel composite oxide of spherical secondary particles which is an aggregate of primary particles was produced. The average particle size of the secondary particles at this time was 8.9 μm, and the primary particle size was about 0.5 μm as judged from the SEM observation image. FIG. 3 shows a SEM photograph of the secondary particles obtained.

Each mass of the raw material used in the above process is such that the molar ratio of each element in the lithium nickel composite oxide which is the final target product is Ni: Co: Al: Li = 0.82: 0.15: 0.03. : Weighed to 1.05. As a result, the chemical composition of the lithium nickel composite oxide was Li _1.050 Ni _0.821 Co _0.147 Al _0.032 O _2.06 .

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 1 and 2, respectively.

(Comparative Example 4)
Cobalt oxide (manufactured by Wako Pure Chemical Industries), nickel oxide (manufactured by Wako Pure Chemical Industries), aluminum hydroxide (manufactured by Wako Pure Chemical Industries), and lithium hydroxide monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) have the same molar ratio as in Example 1. And weighed and mixed with a ball mill. The mixture was calcined in an electric furnace in an oxygen atmosphere for a time: 3 hours and a temperature: 500 ° C., then fired under conditions of a time: 20 hours, a temperature: 730 ° C., and then cooled to the room temperature. did. Lithium nickel composite oxide in which primary particles having an average particle diameter of 0.8 μm were monodispersed was manufactured by pulverization after furnace cooling. The chemical composition of the obtained lithium nickel composite oxide was Li _1.053 Ni _0.819 Co _0.149 Al _0.032 O _2.08 .

  Therefore, Comparative Example 4 differs from Examples 1 to 6 in that aluminum is added before roasting at 1000 ° C. Moreover, in Comparative Example 4, unlike Examples 1-6, chlorine is not added. Further, Comparative Example 4 differs from Comparative Example 3 in that primary particles are obtained by crushing the obtained secondary particles.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 1 and 2, respectively.

  In Examples 1 to 6 within the scope of the first invention, as shown in Table 1, the average particle diameter of the primary particles is in the range of 2 to 8 μm. There were no broken particles. In addition, it was confirmed by the measurement by SEM and a powder X-ray-diffraction apparatus that all the lithium nickel complex oxides of Examples 1 to 6 were single crystals. The characteristics of the batteries produced using the lithium nickel composite oxides of Examples 1 to 6 as the positive electrode are as shown in Table 2. The initial discharge capacity is 188 to 194 (mAh / g), and the capacity retention rate is 88 to 91. (%) And the output value was 77.5 to 84.7 (mW), both of which were good.

  In Examples 1 to 3, the molar ratio of chlorine added before roasting the lithium nickel composite oxide according to the present invention at 1000 ° C. was changed. Therefore, as described above, the characteristics of the obtained lithium nickel composite oxide and the characteristics of the battery produced using the obtained lithium nickel composite oxide as the positive electrode were also good. However, when the added chlorine molar ratio is close to the lower limit of the range of the present invention, the primary particle diameter of Example 2 is as small as 2.2 μm, and the capacity retention rate and output value of the fabricated battery are also compared with Examples 1 and 3. It was a little small.

  In Examples 4 to 6, the kind of the chloride added before roasting the lithium nickel composite oxide at 1000 ° C. is changed (the chlorine molar ratio is 2.5%, which is the same). The initial discharge capacity, the capacity retention rate, and the output value of the lithium battery are almost the same, and it is thought that the molar ratio of chlorine to be added affects the characteristics of the lithium battery.

  In Comparative Example 1, the molar ratio of chlorine to be added is 0.05%, which is lower than the lower limit value of the molar ratio of chlorine in the production method according to the first invention. The particle size was 1.4 μm, which was less than 2 μm. As for the characteristics of the produced battery, the capacity retention rate was about 15% smaller than those in Examples 1 to 6, and the output value was about 30% smaller than those in Examples 1 to 6.

  In Comparative Example 2, the molar ratio of chlorine to be added is 20%, which exceeds the upper limit value of the chlorine molar ratio in the production method according to the first invention. Since the molar ratio of the added chlorine is large, the grain growth itself is good and the average particle diameter is as large as 7.8 μm. However, the initial discharge capacity of the fabricated battery is compared with Examples 1-6. The result was about 10% smaller and the capacity retention rate was about 8% smaller.

  Comparative Example 3 is different from Examples 1 to 6 in that aluminum is added before roasting at 1000 ° C., and is different from Examples 1 to 6 in that chlorine is not added. Since no chlorine was added, grain growth was hardly carried out, and the average primary particle diameter was 0.5 μm. Further, since the obtained lithium nickel composite oxide formed secondary particles, about 15% of the particles were broken by the pressure test. FIG. 4 shows an SEM photograph of the secondary particles after the pressure test. Moreover, the output value of the produced battery was about 35% smaller than those of Examples 1 to 6, and the capacity retention rate was also about 10% smaller.

  Comparative Example 4 is different from Examples 1 to 6 in that aluminum is added before roasting at 1000 ° C., and is different from Examples 1 to 6 in that chlorine is not added. Furthermore, it differs from Comparative Example 3 in that primary particles are obtained by crushing the obtained secondary particles. Since no chlorine was added, the grain growth was hardly carried out, and the average particle diameter of the primary particles was 0.8 μm. Moreover, the output value of the produced battery was about 30% smaller than those of Examples 1 to 6, and the capacity retention rate was also about 14% smaller.

"Examples 7 to 10, Comparative Examples 5 to 8"
(Example 7)
Nickel sulfate hexahydrate (manufactured by Wako Pure Chemical Industries), cobalt sulfate heptahydrate (manufactured by Wako Pure Chemical Industries), and aluminum sulfate (manufactured by Wako Pure Chemical Industries) were mixed in a desired ratio to prepare an aqueous solution. This aqueous solution was dropped into an agitated reaction tank with a discharge port with water kept at 50 ° C. simultaneously with aqueous ammonia (manufactured by Wako Pure Chemical Industries) and aqueous caustic soda (manufactured by Wako Pure Chemical Industries). The pH was maintained at 11.5 and the residence time was controlled to be 11 hours. Thus, spherical nickel hydroxide containing Co and Al was produced by a reactive crystallization method. The nickel hydroxide was spherical secondary particles in which primary particles were aggregated.

The number of moles of Cl in the nickel hydroxide was 5.7% with respect to the total number of moles of metal elements in the obtained Co and Al-containing nickel hydroxide (number of moles of Ni + number of moles of Co + number of moles of Al). Then, vanadium chloride (VCl ₃ ) (manufactured by Wako Pure Chemical Industries) was calculated and weighed. The weighed VCl ₃ powder was dissolved in pure water, but the amount of pure water was such that it did not become a paste even when the VCl ₃ powder was dissolved. The obtained VCl ₃ aqueous solution was uniformly sprayed on the nickel hydroxide and mixed. The mixed powder was roasted at 1000 ° C. to form an oxide, and then mixed with lithium hydroxide monohydrate (manufactured by Wako Pure Chemical Industries) in a V blender so as to have a desired composition. The mixture was calcined in an electric furnace in an oxygen atmosphere at a time of 3 hours and at a temperature of 500 ° C., then fired at a time of 20 hours and a temperature of 730 ° C., and then cooled to room temperature. did. After furnace cooling, a monodispersed lithium nickel composite oxide of primary particles was produced by pulverization.

  It was confirmed by JEOL scanning electron microscope “JSM-5510” that the obtained primary particles were single crystals. At this time, the average particle diameter of the primary particles was 6.2 μm. FIG. 5 shows an SEM photograph of the primary particles obtained.

Each mass of the raw material used in the above process is such that the molar ratio of each element in the lithium nickel composite oxide as the final target product is Ni: Co: Al: Li = 0.82: 0.15: 0.03. : Weighed to 1.05. As a result, the chemical composition of the obtained lithium nickel composite oxide was Li _1.049 Ni _0.811 Co _0.142 Al _0.028 V _0.019 O _2.05 .

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 3 and 4, respectively.

(Example 8)
In Example 7, the number of moles of Cl in the Co.Al-containing nickel hydroxide was 5 with respect to the total number of moles of metal elements in the nickel hydroxide (number of moles of Ni + number of moles of Co + number of moles of Al). The sample was prepared to be 0.7%, but in Example 8, the sample was prepared to be 1.0%. The other conditions were the same as in Example 7. As a result, a lithium nickel composite oxide having an average particle size of 2.3 μm and a chemical composition of Li _1.053 Ni _0.820 Co _0.146 Al _0.031 V _0.003 O _2.12 . The chloride used to introduce Cl into nickel hydroxide is vanadium chloride (VCl ₃ ), which is the same as in Example 7.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 3 and 4, respectively.

Example 9
In Example 7, the number of moles of Cl in the Co.Al-containing nickel hydroxide was 5 with respect to the total number of moles of metal elements in the nickel hydroxide (number of moles of Ni + number of moles of Co + number of moles of Al). The sample was prepared to be 0.7%, but in Example 9, the sample was prepared to be 14.3%. The other conditions were the same as in Example 7. As a result, a lithium nickel composite oxide having an average particle size of 10.2 μm and a chemical composition of Li _1.051 Ni _0.785 Co _0.143 Al _0.027 V _0.045 O _2.08 was obtained. The chloride used to introduce Cl into nickel hydroxide is vanadium chloride (VCl ₃ ), which is the same as in Example 7.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 3 and 4, respectively.

(Example 10)
Nickel sulfate hexahydrate (manufactured by Wako Pure Chemical Industries) and cobalt sulfate hexahydrate (manufactured by Wako Pure Chemical Industries) were mixed and adjusted so as to have a desired ratio. This aqueous solution was dropped into an agitated reaction tank with a discharge port with water kept at 50 ° C. simultaneously with aqueous ammonia (manufactured by Wako Pure Chemical Industries) and aqueous caustic soda (manufactured by Wako Pure Chemical Industries). The pH was kept at 11.5 and the residence time was controlled to be 11 hours. In this way, spherical nickel hydroxide containing Co was produced by a reactive crystallization method. The nickel hydroxide was spherical secondary particles in which primary particles were aggregated.

  The nickel hydroxide was put into a container filled with water so as to have a slurry concentration of 130 g / L and stirred. To this, sodium aluminate (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred for 1 hour so that the desired ratio was obtained, and then adjusted to pH 9.5 with dilute sulfuric acid, and Co-containing aluminum hydroxide was coated. Nickel hydroxide was produced.

The conditions other than the above production conditions were the same as in Example 7. As a result, a lithium nickel composite oxide having an average particle size of 5.8 μm and a chemical composition of Li _1.048 Ni _0.807 Co _0.146 Al _0.029 V _0.018 O _2.04 was obtained. It was. The chloride used to introduce Cl into nickel hydroxide is vanadium chloride (VCl ₃ ), which is the same as in Example 7.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 7. . The measurement and evaluation results are shown in Tables 3 and 4, respectively.

(Comparative Example 5)
In Example 7, the number of moles of Cl in the Co.Al-containing nickel hydroxide was 5 with respect to the total number of moles of metal elements in the nickel hydroxide (number of moles of Ni + number of moles of Co + number of moles of Al). The sample was prepared to be 0.7%, but in Comparative Example 5, the sample was prepared to be 0.2%. The other conditions were the same as in Example 7. As a result, a lithium nickel composite oxide having an average particle diameter of 0.8 μm and a chemical composition of Li _1.053 Ni _0.821 Co _0.145 Al _0.033 V _0.001 O _2.17 was obtained. The chloride used to introduce Cl into nickel hydroxide is vanadium chloride (VCl ₃ ), which is the same as in Example 7.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 3 and 4, respectively.

(Comparative Example 6)
In Example 7, the number of moles of Cl in the Co.Al-containing nickel hydroxide was 5 with respect to the total number of metal elements in the nickel hydroxide (number of moles of Ni + number of moles of Co + number of moles of Al). The sample was prepared so as to be 7%, but in Comparative Example 6, the sample was prepared so as to be 19.8%. The other conditions were the same as in Example 7. As a result, a lithium nickel composite oxide having an average particle size of 13.3 μm and a chemical composition of Li _1.052 Ni _0.769 Co _0.141 Al _0.028 V _0.062 O _2.10 was obtained. The chloride used to introduce Cl into nickel hydroxide is vanadium chloride (VCl ₃ ), which is the same as in Example 7.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 3 and 4, respectively.

(Comparative Example 7)
In the same manner as in Example 9, the Co.Al-containing nickel hydroxide was uniformly sprayed with an aqueous vanadium chloride solution and mixed to obtain a mixed powder.

The mixed powder was roasted at 800 ° C. to obtain an oxide, and the subsequent treatment was the same as in Example 7. As a result, a lithium nickel composite oxide having an average particle size of 1.2 μm and a chemical composition of Li _1.048 Ni _0.782 Co _0.146 Al _0.029 V _0.043 O _2.08 was obtained.

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 3 and 4, respectively.

(Comparative Example 8)
In the same manner as in Example 8, the Co.Al-containing nickel hydroxide was uniformly sprayed with an aqueous vanadium chloride solution and mixed to obtain a mixed powder.

  This mixed powder was roasted at 1500 ° C. to obtain an oxide, and the subsequent treatment was the same as in Example 7. As a result, a powder in which a lithium nickel composite oxide having a primary particle size of several tens of μm and a nickel composite oxide of several μm was mixed by a segregation reaction of a Li compound was obtained.

  FIG. 6 shows the result of measurement of the obtained mixed powder by powder X-ray diffraction. As can be seen from FIG. 6, the obtained mixed powder has a large proportion of the lithium nickel composite oxide, but it is understood that the nickel composite oxide is also mixed to some extent. Accordingly, one having a primary particle size of more than 10 μm is considered a lithium nickel composite oxide, and one having a primary particle size of several μm is considered a nickel composite oxide.

(Comparative Example 9)
After producing spherical Co.Al-containing nickel hydroxide in the same process as in Example 7, lithium hydroxide monohydrate (manufactured by Wako Pure Chemical Industries) was mixed in a V blender so as to have a desired composition. The mixture was calcined in an electric furnace in an oxygen atmosphere at a time of 3 hours and at a temperature of 500 ° C., then fired at a time of 20 hours and a temperature of 730 ° C., and then cooled to room temperature. did. After the furnace cooling, pulverization was performed to produce lithium nickel composite oxide with spherical secondary particles.

  The shape of the obtained secondary particles was confirmed with a scanning electron microscope “JSM-5510” (manufactured by JEOL Ltd.). The average particle diameter of the primary particles was 0.3 μm, and the average particle diameter of the secondary particles was 8.3 μm.

Each mass of the raw material used in the above process is such that the molar ratio of each element in the lithium nickel composite oxide as the final target product is Ni: Co: Al: Li = 0.82: 0.15: 0.03. : Weighed to 1.05, and the resulting lithium nickel composite oxide had a chemical composition of Li _1.049 Ni _0.818 Co _0.147 Al _0.035 O _2.21 .

  Measurement by SEM as to whether or not particle breakage occurred after a pressure test on the obtained lithium nickel composite oxide powder and evaluation of the characteristics of the obtained battery were performed in the same manner as in Example 1. . The measurement and evaluation results are shown in Tables 3 and 4, respectively.

  In Examples 7 to 10 within the scope of the second invention, as shown in Table 3, the average particle diameter of the primary particles is in the range of 2 to 12 μm. There were no broken particles. In addition, it was confirmed by the measurement by SEM and a powder X-ray-diffraction apparatus that all the lithium nickel complex oxides of Examples 7 to 10 were single crystals. The characteristics of the batteries produced using the lithium nickel composite oxides of Examples 7 to 10 as the positive electrode are as shown in Table 4. The initial discharge capacity is 183 to 194 (mAh / g), and the capacity retention rate is 85 to 92. (%) And the output value was 79.2 to 84.6 (mW), both of which were good.

  In Examples 7 to 10, the molar ratio of chlorine added before roasting the lithium nickel composite oxide according to the present invention at 1000 ° C. was changed. Therefore, as described above, the characteristics of the obtained lithium nickel composite oxide and the characteristics of the battery produced using the obtained lithium nickel composite oxide as the positive electrode were also good. However, the primary particle diameter of Example 8 in which the added chlorine molar ratio is close to the lower limit of the range of the present invention is as small as 2.3 μm, and the capacity retention rate and output value of the produced batteries are also as described in Examples 7, 9 and Compared to 10, it was slightly smaller.

In Example 10, vanadium chloride (VCl ₃ ) was mixed with Co-containing nickel hydroxide coated with aluminum hydroxide and then roasted at 1000 ° C., so that vanadium chloride ( VCl ₃ ) is mixed and then roasted at 1000 ° C., but different from Examples 7-9, the initial discharge capacity (194 (mAh / g)), capacity retention rate (90%) and output of Example 10 All values (82.8 mW) are comparable to Examples 7-9. Therefore, even by roasting a mixture of vanadium chloride (VCl ₃₎ the Co-containing nickel compound aluminum compound is coated on the surface, a mixture of vanadium chloride (VCl ₃₎ to Co · Al-containing nickel hydroxide It turns out that the same effect as the case of roasting is acquired.

  In Comparative Example 5, the molar ratio of chlorine to be added is 0.2%, which is lower than the lower limit value of the chlorine molar ratio in the production method according to the present invention. Was 0.8 μm, which was less than 2 μm. As for the characteristics of the manufactured battery, the capacity retention rate was about 13% smaller than those in Examples 1 to 4, and the output value was about 30% smaller than those in Examples 1 to 4.

  In Comparative Example 6, the molar ratio of chlorine to be added is 19.8%, which exceeds the upper limit value of the chlorine molar ratio in the production method according to the present invention. Since the molar ratio of added chlorine was large, the grain growth was excessive, and the average particle size was as large as 13.3 μm. For this reason, the initial discharge capacity of the fabricated battery was about 10% smaller than those of Examples 1 to 4, the capacity retention rate was about 8% smaller, and the output value was about 12% smaller.

  Comparative Example 7 is the same molar ratio of chlorine as Example 3, but the roasting temperature was lowered from 1000 ° C to 800 ° C, and the roasting temperature (900-1300 ° C of the production method according to the second invention). ) Is lower than the lower limit value. For this reason, although the amount of chlorine was sufficient, since the roasting temperature was too low, the average particle diameter of the primary particles was as small as 1.2 μm and did not reach 2 μm. Since the produced battery also has a small primary particle size, the capacity retention rate was about 23% smaller and the output value about 30% smaller than Example 3.

  Although the comparative example 8 is the chlorine molar ratio of the same amount as Example 2, the roasting temperature is raised from 1000 degreeC to 1500 degreeC, and the roasting temperature (900-1300 degreeC of the manufacturing method which concerns on this 2nd invention is carried out. The baking temperature is higher than the upper limit value. For this reason, although the amount of chlorine is close to the lower limit in the production method according to the second invention, the diameter is very high at about 6.8 μm at the time when the Co / Al-containing nickel oxide is produced due to the high roasting temperature. It became large primary particles. For this reason, the reactivity with Li compound worsened. In addition, the solution flowed downward due to gravity before the reaction, resulting in a mixture of a lithium nickel composite oxide having a very large average particle diameter of several tens of μm and a nickel composite oxide of several μm.

  Comparative Example 9 is different from Examples 1 to 3 in that chlorine is not added. Since vanadium chloride was not added, the grain growth was hardly carried out, and the average particle diameter of the primary particles was 0.3 μm. Moreover, since the obtained lithium nickel composite oxide hardly caused grain growth, secondary particles were maintained, and about 20% of the whole particles were broken by the pressure test. Moreover, the output value of the produced battery was about 30% smaller than those of Examples 1 to 3, and the capacity retention rate was about 8% smaller.

2 is a SEM photograph of primary particles of Example 1. It is sectional drawing of a 2032 type coin battery produced for evaluation of a positive electrode active material. 4 is a SEM photograph of secondary particles of Comparative Example 3. 6 is a SEM photograph after a pressure test of secondary particles of Comparative Example 3. 10 is a SEM photograph of primary particles of Example 7. 10 is a powder X-ray diffraction pattern of a mixture produced in Comparative Example 8.

Explanation of symbols

1: Positive electrode 2: Separator 3: Negative electrode 4: Gasket 5: Positive electrode can 6: Negative electrode can 7: Coin battery

Claims (11)

A positive electrode active material for a non-aqueous secondary battery containing nickel and lithium as main components, the composition is represented by the following general formula,
_{Li x Ni 1-pqr Co p} Al q A r O 2-y
(However, the range of values of x, p, q, r, y in the formula is 0.8 ≦ x ≦ 1.3, 0 <p ≦ 0.2, 0 <q ≦ 0.1, 0 ≦ r. ≦ 0.1, −0.3 <y <0.1, and A in the formula is Ti, V, In, Cr, Fe, Sn, Cu, Zn, Mn, Mg, Ga, Ni, Co, (It represents at least one element selected from the group consisting of Zr, Bi, Ge, Nb, Ta, Be, Ca, Sr, Ba, and Sc.)
And the positive electrode active material for non-aqueous secondary batteries characterized by consisting of primary particles which are single crystals and have an average particle diameter of 2 to 8 μm. Obtaining a nickel compound containing cobalt from the nickel compound and the cobalt compound;
An inorganic chloride or a nickel compound containing cobalt so that the number of moles of chlorine is in the range of 0.1 to 15% with respect to the total number of moles of nickel and cobalt in the compound. Adding an inorganic chloride oxide and mixing to obtain a mixture;
Roasting the mixture at a temperature of 800-1300 ° C. to obtain an oxide composed of a single crystal having an average particle size of 2-8 μm;
A step of obtaining a mixture by mixing the oxide with an aluminum compound and a lithium compound, or coating the surface of the oxide with an aluminum compound and then mixing the lithium compound; and firing the mixture at 600 to 800 ° C. Obtaining a lithium nickel composite oxide;
The manufacturing method of the positive electrode active material for non-aqueous secondary batteries characterized by comprising.   The inorganic chloride or inorganic chloride oxide is Ti, V, In, Cr, Fe, Sn, Cu, Zn, Mn, Mg, Ga, Ni, Co, Zr, Bi, Ge, Nb, Ta, Be, Ca. The method for producing a positive electrode active material for a non-aqueous secondary battery according to claim 2, which is a chloride or a chloride oxide of at least one element selected from the group consisting of Sr, Ba, and Sc.   The method for producing a positive electrode active material for a non-aqueous secondary battery according to claim 2 or 3, wherein the nickel compound containing cobalt is composed of at least one of a hydroxide, an oxyhydroxide, and a carbonate.   The positive electrode active for a non-aqueous secondary battery according to any one of claims 2 to 4, wherein the aluminum compound comprises at least one of a hydroxide, an oxyhydroxide, an oxide, a sulfate, and an aluminate. A method for producing a substance.   The lithium compound comprises at least one of hydroxide, oxyhydroxide, oxide, carbonate, sulfate, nitrate, dicarboxylate, fatty acid salt, citrate, alkyl compound and halogen compound. The manufacturing method of the positive electrode active material for non-aqueous secondary batteries in any one of claim | item 2 -5. A positive electrode active material for a non-aqueous secondary battery containing nickel and lithium as main components, the composition is represented by the following general formula,
_{Li x Ni 1-pqr Co p} Al q V r O 2-y
(However, the ranges of values of x, p, q, r, and y in the formula are 0.8 ≦ x ≦ 1.3, 0 <p ≦ 0.2, 0 <q ≦ 0.1, 0 <r. ≦ 0.05, −0.3 <y <0.1.)
And the positive electrode active material for non-aqueous secondary batteries characterized by consisting of primary particles which are single crystals and have an average particle diameter of 2 to 12 μm. Step of obtaining nickel compound containing cobalt and aluminum from nickel compound, cobalt compound and aluminum compound, or obtaining nickel compound containing cobalt from nickel compound and cobalt compound, and then coating the surface of nickel compound with aluminum compound And obtaining a cobalt-containing nickel compound coated with an aluminum compound,
Vanadium chloride is added to the compound containing nickel as a main component so that the number of moles of chlorine is in the range of 0.5 to 15% with respect to the total number of moles of nickel, cobalt, and aluminum in the compound. Mixing to obtain a mixture;
Roasting the mixture at a temperature of 900-1300 ° C. to form an oxide;
A step of mixing a lithium compound with the oxide to obtain a mixture mainly composed of lithium nickel;
Firing the mixture at 600 to 800 ° C. to obtain a lithium nickel composite oxide;
The manufacturing method of the positive electrode active material for non-aqueous secondary batteries characterized by comprising.   9. The positive electrode active material for a non-aqueous secondary battery according to claim 8, wherein the nickel-based compound comprises at least one of a hydroxide, an oxyhydroxide, and a carbonate. Production method.   The aluminum compound used for said surface coating consists of at least one of a hydroxide, an oxyhydroxide, an oxide, a sulfate, and an aluminate, The non-of Claim 8 or 9 characterized by the above-mentioned. A method for producing a positive electrode active material for an aqueous secondary battery.   The lithium compound is composed of at least one of hydroxide, oxyhydroxide, oxide, carbonate, sulfate, nitrate, dicarboxylate, fatty acid salt, citrate, alkyl compound and halogen compound. The manufacturing method of the positive electrode active material for non-aqueous secondary batteries in any one of Claims 8-10 characterized by these.