JP2019021423A - Positive electrode active material precursor for nonaqueous electrolyte secondary battery, positive electrode active material for nonaqueous electrolyte secondary battery, method for manufacturing the positive electrode active material precursor for nonaqueous electrolyte secondary battery, and method for manufacturing the positive electrode active material for nonaqueous electrolyte secondary battery - Google Patents

Abstract

To provide a positive electrode active material precursor for a nonaqueous electrolyte secondary battery, by which a positive electrode active material for a nonaqueous electrolyte secondary battery, having a higher density can be formed.SOLUTION: Provided is a positive electrode active material precursor for a nonaqueous electrolyte secondary battery, which comprises: a nickel cobalt manganese carbonate composite represented by the general formula, NiCoMnMCO(where x+y+z+t=1, 0.05≤x≤0.3, 0.1≤y≤0.4, 0.55≤z≤0.8 and 0≤t≤0.1, and M represents one or more additive elements selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo and W); and a functional group including hydrogen, wherein the substance amount ratio H/Me of the hydrogen H and a metal component Me included therein is less than 1.60. The positive electrode active material precursor includes secondary particles resulting from agglomeration of primary particles. The secondary particles have an average particle diameter of 15 μm or more and 45 μm or less.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a positive electrode active material precursor for a non-aqueous electrolyte secondary battery, a positive electrode active material for a non-aqueous electrolyte secondary battery, a method for producing a positive electrode active material precursor for a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery. The present invention relates to a method for producing a positive electrode active material.

  In recent years, with the widespread use of portable electronic devices such as mobile phones and laptop computers, development of small and lightweight non-aqueous electrolyte secondary batteries having high energy density is strongly desired. In addition, development of a high-power secondary battery is strongly desired as a large battery such as a motor drive power source.

  As a secondary battery that satisfies these requirements, there is a lithium ion secondary battery. A lithium ion secondary battery includes a negative electrode, a positive electrode, an electrolyte, and the like, and a material capable of desorbing and inserting lithium is used as the negative electrode active material and the positive electrode active material.

  Research and development of lithium-ion secondary batteries are currently being actively conducted. Among them, a lithium ion secondary battery using a layered or spinel type lithium metal composite oxide as a positive electrode material can be used as a battery having a high energy density because a high voltage of 4V can be obtained.

As a positive electrode material of the lithium ion secondary battery, lithium cobalt composite oxide (LiCoO ₂ ), which is currently relatively easy to synthesize, lithium nickel composite oxide (LiNiO ₂ ) using nickel cheaper than cobalt, lithium Nickel cobalt manganese composite oxide (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ), lithium manganese composite oxide (LiMn ₂ O ₄ ) using manganese, lithium nickel manganese composite oxide (LiNi _0.5 Mn _0.5 O _2), lithium-rich nickel-cobalt-manganese composite oxide _{(Li 2 MnO 3 -LiNi x Mn} y Co z O 2) lithium composite oxide or the like is proposed.

  Among these positive electrode active materials, in recent years, lithium-excess nickel cobalt manganese composite oxides with high capacity and excellent thermal stability have attracted attention. This composite oxide is a layered compound like lithium cobalt composite oxide, lithium nickel composite oxide, and the like (see, for example, Non-Patent Document 1).

  And the manufacturing method of the precursor for obtaining the lithium excess nickel cobalt manganese complex oxide is disclosed by patent document 1 and patent document 2, for example.

JP 2011-105588 A JP 2012-252964 A

“High performance lithium-ion batteries: solid solution cathode materials”, FB Technical News, No. 66, January 2011, pages 3-10

  By the way, as a condition for the lithium ion secondary battery to obtain good performance (high cycle characteristics, low resistance, high output), it is necessary to use a compound containing high density (tap density) particles for the positive electrode material. Become. That is, when a battery is manufactured using a positive electrode material having a high tap density, a battery having a high volume energy density is obtained.

  However, when a positive electrode active material is produced using the precursors disclosed in Patent Documents 1 and 2, a sufficient tap density has not been achieved.

  Accordingly, in view of the problems of the above-described conventional technology, according to one aspect of the present invention, there is provided a positive electrode active material precursor for a non-aqueous electrolyte secondary battery that can form a higher-density positive electrode active material for a non-aqueous electrolyte secondary battery. With the goal.

In order to solve the above problems, according to one aspect of the present invention,
General formula Ni _x Co _y Mn _z M _t CO ₃ (where x + y + z + t = 1, 0.05 ≦ x ≦ 0.3, 0.1 ≦ y ≦ 0.4, 0.55 ≦ z ≦ 0 .8, 0 ≦ t ≦ 0.1, and M is one or more additive elements selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W). A nickel cobalt manganese carbonate composite represented,
A functional group containing hydrogen,
H / Me, which is a substance amount ratio between the hydrogen H contained and the metal component Me contained, is less than 1.60,
Including secondary particles in which a plurality of primary particles are aggregated,
The secondary particles provide a positive electrode active material precursor for a non-aqueous electrolyte secondary battery having an average particle size of 15 μm or more and 45 μm or less.

  According to one embodiment of the present invention, a positive electrode active material precursor for a non-aqueous electrolyte secondary battery that can form a higher-density positive electrode active material for a non-aqueous electrolyte secondary battery can be provided.

The flowchart of the manufacturing method of the positive electrode active material precursor for non-aqueous electrolyte secondary batteries of embodiment of this invention. The flowchart of the manufacturing method of the positive electrode active material precursor for non-aqueous electrolyte secondary batteries of embodiment of this invention. The cross-sectional SEM image of the positive electrode active material obtained in Example 1 which concerns on this invention. The cross-sectional block diagram of the secondary battery produced by the Example and the comparative example. 4 is a cross-sectional SEM image of the positive electrode active material obtained in Comparative Example 1. FIG.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and the following embodiments are not departed from the scope of the present invention. Various modifications and substitutions can be made.
[Positive electrode active material precursor for non-aqueous electrolyte secondary battery]
In the present embodiment, first, a configuration example of a positive electrode active material precursor for a nonaqueous electrolyte secondary battery will be described.

The positive electrode active material precursor for a non-aqueous electrolyte secondary battery of this embodiment has a general formula Ni _x Co _y Mn _z M _t CO ₃ (where x + y + z + t = 1, 0.05 ≦ x ≦ 0.3 0.1 ≦ y ≦ 0.4, 0.55 ≦ z ≦ 0.8, 0 ≦ t ≦ 0.1, and M is Mg, Ca, Al, Ti, V, Cr, Zr, Nb, 1 or more additional elements selected from Mo and W.) and a nickel-cobalt-manganese carbonate composite represented by (2) and a functional group containing hydrogen.

  And H / Me which is a substance amount ratio of the hydrogen H to contain and the metal component Me to contain can be less than 1.60, and the secondary particle which the several primary particle aggregated can be included. Moreover, the average particle diameter of the secondary particles can be 15 μm or more and 45 μm or less.

  As described above, the positive electrode active material precursor for a non-aqueous electrolyte secondary battery of the present embodiment (hereinafter, also simply referred to as “precursor”) includes a nickel-cobalt-manganese carbonate composite and a functional group containing hydrogen. Can be included. In addition, a precursor can also be comprised from the nickel cobalt manganese carbonate composite and the functional group containing hydrogen.

  The precursor of this embodiment can include substantially spherical secondary particles formed by agglomerating a plurality of fine primary particles, and can also be composed of such secondary particles.

  The precursor of the present embodiment including the nickel cobalt manganese carbonate composite and the functional group containing hydrogen has a large particle size, high uniformity, and high density (high tap density). It can be used as a raw material, that is, a precursor of a positive electrode active material for an aqueous electrolyte secondary battery.

Below, the precursor of this embodiment is demonstrated concretely.
(1) Composition As described above, the nickel cobalt manganese carbonate composite is a nickel cobalt manganese composite in the form of a basic carbonate represented by the general formula: Ni _x Co _y Mn _z M _t CO ₃ .

  However, in the above general formula, x + y + z + t = 1, 0.05 ≦ x ≦ 0.3, 0.1 ≦ y ≦ 0.4, 0.55 ≦ z ≦ 0.8, 0 ≦ t ≦ 0.1. Satisfying, M is one or more additive elements selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W.

  In order to further improve battery characteristics such as cycle characteristics and output characteristics when the precursor of this embodiment is used as a precursor of a positive electrode active material of a non-aqueous electrolyte secondary battery, a nickel cobalt manganese carbonate composite is used. As described above, an additive element can also be added. One or more additive elements selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W are contained in the secondary particles within a predetermined atomic ratio t. It is preferable to uniformly distribute and / or uniformly coat the surface of the secondary particles.

  However, in the nickel-cobalt-manganese carbonate composite, when the atomic ratio t of the additive elements exceeds 0.1, the metal elements contributing to the oxidation-reduction reaction (Redox reaction) are reduced, and the battery capacity may be reduced. .

  Further, even when the nickel cobalt manganese carbonate composite does not contain an additive element, the positive electrode active material produced using the precursor of the present embodiment has sufficient battery characteristics such as cycle characteristics and output characteristics. It has characteristics. For this reason, it is not necessary to contain an additive element.

  It is preferable that the additive element is uniformly distributed and / or uniformly coated on the surface of the secondary particles contained in the precursor (hereinafter also simply referred to as “precursor particles”).

  In the nickel cobalt manganese carbonate composite, the state of the additive element is not particularly limited. However, it is preferable that the additive element is uniformly distributed and / or uniformly coated on the surface inside the nickel cobalt manganese carbonate composite as described above. This is because the additive element is distributed (covered) inside and / or on the surface of the nickel cobalt manganese carbonate composite, so that the battery characteristics are improved when the precursor of this embodiment is used as the precursor of the positive electrode active material. This is because it can be particularly improved.

  In addition, in the case of the nickel cobalt manganese carbonate composite, in order to sufficiently enhance the effect of improving the battery characteristics even when the addition amount of one or more additional elements is particularly small, the carbonate composite from the inside of the carbonate composite It is preferable to increase the concentration of one or more additional elements on the surface.

  As described above, in the nickel cobalt manganese carbonate composite, even if the addition amount of one or more kinds of additional elements is small, the effect of improving the battery characteristics can be obtained and the decrease in the battery capacity can be suppressed. it can.

  Moreover, the precursor of this embodiment can contain the functional group containing hydrogen as stated above. Examples of the functional group containing hydrogen include a hydrogen group and a hydroxyl group. The functional group containing hydrogen is mixed in in the production process, and H / Me, which is a substance amount ratio between the hydrogen H contained in the precursor of the present embodiment and the contained metal component Me, is less than 1.60. Therefore, when the positive electrode active material is used, the number ratio of dense particles can be increased, which is preferable. This is because a higher density positive electrode active material can be obtained by increasing the number ratio of dense particles in the secondary particles of the positive electrode active material. The lower limit value of H / Me can be made larger than 0, for example.

  The metal component Me contained in the precursor mentioned here includes Ni, Co, Mn, and M which is an additive element mentioned in the above general formula.

Moreover, the precursor of this embodiment can also contain components other than the nickel cobalt manganese carbonate composite and the functional group containing hydrogen, but contains the nickel cobalt manganese carbonate composite and hydrogen. It can also consist of functional groups. In addition, even if the precursor of this embodiment is a case where it is comprised from the group containing a nickel cobalt manganese carbonate composite and hydrogen, it does not exclude containing an inevitable component in a manufacturing process or the like. Absent.
(2) Average particle diameter The precursor of this embodiment can contain the secondary particle which the primary particle aggregated, and this secondary particle can have a substantially spherical shape. The secondary particles preferably have an average particle size of 15 μm or more and 45 μm or less. In particular, it is more preferable that the secondary particles contained in the precursor of the present embodiment have an average particle size of 15 μm or more and 35 μm or less.

  The average particle size is the particle size distribution obtained by the laser diffraction / scattering method, in which the number of particles in each particle size is accumulated from the larger particle size side, and the accumulated volume is 50% of the total volume of all particles. Means diameter. Hereinafter, the average particle diameter in the present specification has the same meaning.

  By setting the average particle size of the secondary particles contained in the precursor of this embodiment to 15 μm or more and 45 μm or less, for example, particles containing a positive electrode active material obtained using the precursor of this embodiment as a raw material are The average particle size can be set.

  For this reason, in the non-aqueous electrolyte secondary battery using the positive electrode active material produced from the precursor of this embodiment, the positive electrode has a high packing density, and the battery capacity and output characteristics can be improved. Thus, since the average particle diameter of the secondary particles contained in the precursor of this embodiment correlates with the particle diameter of the particles contained in the obtained positive electrode active material, a battery using this positive electrode active material as the positive electrode material. Closely related to the characteristics of

  By making the average particle size of the secondary particles contained in the precursor 15 μm or more, the average particle size of the secondary particles contained in the positive electrode active material obtained from the precursor is sufficiently large, for example, 12 μm or more. The packing density of the positive electrode can be increased, and the battery capacity per volume can be increased.

  On the other hand, when the average particle size of the secondary particles contained in the precursor exceeds 45 μm, the specific surface area of the obtained positive electrode active material is decreased, and the interface with the electrolyte is decreased, thereby increasing the resistance of the positive electrode. The output characteristics of the battery may be degraded.

For this reason, it is preferable that the average particle diameter of the secondary particle which the precursor of this embodiment contains is 15 micrometers or more and 45 micrometers or less.
(3) Particle size distribution The secondary particles contained in the precursor of the present embodiment have an index [(d ₉₀ -d ₁₀ ) / average particle size] of 0.52 or less, which is an index indicating the spread of the particle size distribution. Is more preferable, and 0.50 or less is more preferable.

D ₉₀ and d ₁₀ are the particle size distributions obtained by the laser diffraction / scattering method, respectively, and the number of particles in each particle size is accumulated from the smaller particle size side, and the accumulated volume is 90% of the total volume of all particles. Mean particle size at 10%. Hereinafter, d ₉₀ and d ₁₀ in this specification have the same meaning.

  Since the particle size distribution of the positive electrode active material produced using the precursor of the present embodiment is strongly influenced by the particle size distribution of the precursor as a raw material, fine particles and / or coarse particles (large particle) are contained in the precursor. If mixed, the same particles are present in the positive electrode active material.

That is, in the precursor of this embodiment, when [(d ₉₀ -d ₁₀ ) / average particle size] exceeds 0.52 and the range of the particle size distribution is wide, a positive electrode produced using the precursor There is a possibility that fine particles and / or coarse particles may be present in the active material.

On the other hand, in the precursor, by setting [(d ₉₀ -d ₁₀ ) / average particle size] to 0.52 or less, the positive electrode active material obtained using the precursor also has a narrow particle size distribution range. This is preferable because the particle diameter can be made uniform.

  In addition, when a positive electrode is formed using a positive electrode active material in which a large amount of fine particles are present, heat may be generated due to a local reaction of the fine particles, so that the safety of the battery is lowered and the fine particles are selected. Therefore, the cycle characteristics of the battery may be deteriorated.

  In addition, when a positive electrode is formed using a positive electrode active material having a large amount of coarse particles, a sufficient reaction area between the electrolyte and the positive electrode active material cannot be obtained, and the battery output may decrease due to an increase in reaction resistance. .

  The precursor of this embodiment described above contains substantially spherical secondary particles formed by agglomeration of fine primary particles, has a large particle size, high uniformity, and density (tap density). ).

Therefore, the precursor of this embodiment is particularly suitable as a raw material for the positive electrode active material of the non-aqueous electrolyte secondary battery, has excellent safety, and can be reduced in size and increased in output.
[Method for producing positive electrode active material precursor for non-aqueous electrolyte secondary battery]
Next, a configuration example of a method for producing a positive electrode active material precursor for a non-aqueous electrolyte secondary battery according to the present embodiment (hereinafter also simply referred to as “a precursor production method”) will be described.

  In addition, since the precursor mentioned above can be manufactured with the manufacturing method of the precursor of this embodiment, description is partially abbreviate | omitted about the already demonstrated content.

  In the precursor production method of the present embodiment, a precursor can be obtained by a crystallization reaction, and the obtained precursor can be washed and dried as necessary.

Specifically, the method for producing the precursor of the present embodiment has a general formula Ni _x Co _y Mn _z M _t CO ₃ (where x + y + z + t = 1, 0.05 ≦ x ≦ 0.3, 0 0.1 ≦ y ≦ 0.4, 0.55 ≦ z ≦ 0.8, 0 ≦ t ≦ 0.1, and M is Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, And a nickel-cobalt-manganese carbonate composite represented by the following formula: and a functional group containing hydrogen, and a positive electrode active material precursor for a non-aqueous electrolyte secondary battery. This manufacturing method includes the following steps.

A mixture of an initial aqueous solution containing an ammonium ion donor, an aqueous solution containing nickel as a metal component, an aqueous solution containing cobalt as a metal component, and an aqueous solution containing manganese as a metal component in the presence of carbonate ions. A crystallization process in which nuclei are produced in an aqueous solution and the produced nuclei are grown.
In the crystallization step, the pH value of the mixed aqueous solution can be controlled to 6.5 or more and 9.5 or less on the basis of the reaction temperature of 40 ° C.

  A configuration example of the flow of the precursor manufacturing method of the present embodiment shown in FIG. 1 will be described below. As shown in FIG. 1, the precursor manufacturing method of this embodiment includes a crystallization step.

Hereinafter, the crystallization step of the precursor manufacturing method of the present embodiment will be described in detail.
(1) Crystallization Step As shown in FIG. 1, in the crystallization step, an initial aqueous solution can be prepared by mixing ion-exchanged water (water) and an ammonium ion supplier in a reaction vessel. The initial aqueous solution is preferably adjusted to pH of 6.5 to 9.5 by adding an acidic substance such as sulfate as required, and is adjusted to 7.0 or more and 8.5 or less. It is more preferable.

  In addition, although it does not specifically limit as an ammonium ion supply body, One or more types selected from ammonium carbonate aqueous solution, ammonia water, ammonium chloride aqueous solution, and ammonium sulfate aqueous solution can be used preferably.

  At this time, it is preferable to blow an inert gas such as nitrogen gas so that oxygen does not enter the reaction vessel. That is, the inside of the reaction tank is preferably an inert gas atmosphere, for example, a nitrogen gas atmosphere is preferable. Since the inside of the reaction tank is preferably an inert gas atmosphere also during the crystallization process, the inside of the reaction tank can be an inert gas atmosphere until the crystallization process is completed.

  However, when carbon dioxide gas is used as the carbonate ion source as described later, carbon dioxide may be supplied in addition to or in place of the inert gas in the atmosphere in the reaction vessel. it can.

  By carrying out the crystallization step under an atmosphere containing an inert gas and / or carbon dioxide gas, the H / Me, which is the substance amount ratio between the contained hydrogen and the contained metal component Me, is less than 1.60, The above-described precursor containing secondary particles formed by aggregation of a plurality of primary particles can be obtained.

  In the crystallization step, mixing is performed by adding and mixing an aqueous solution containing nickel as the metal component, an aqueous solution containing cobalt as the metal component, and an aqueous solution containing manganese as the metal component into the initial aqueous solution in the reaction vessel. An aqueous solution can be formed.

  During the crystallization process, when an aqueous solution containing nickel as a metal component is added to the initial aqueous solution, the pH value of the obtained mixed aqueous solution is 6.5 to 9.5 based on the reaction temperature of 40 ° C. It is preferably controlled in a range, and more preferably in a range of 7.0 to 8.5. For this reason, the aqueous solution etc. which contain nickel as a metal component can be gradually dripped at initial stage aqueous solution instead of adding at once.

  During the crystallization process, it is preferable to control the fluctuation range of the pH value of the mixed aqueous solution to be within 0.05 above and below the median value of the pH value. This is because, by setting the fluctuation range of the pH value of the mixed aqueous solution in the above range, the growth of particles contained in the precursor is made substantially constant, and uniform particles having a narrow particle size distribution range can be obtained.

  Further, in order to control the pH of the mixed aqueous solution, a pH adjusting aqueous solution can be dropped together with dropping an aqueous solution containing nickel as a metal component. In this case, the pH adjusting aqueous solution is not particularly limited, and for example, an aqueous solution containing an alkaline substance and / or an ammonium ion supplier can be used. In addition, although it does not specifically limit as an ammonium ion supply body, The substance similar to what was demonstrated in initial stage aqueous solution can be used. Moreover, although it does not specifically limit about an alkaline substance, It is preferable that it is 1 or more types selected from sodium carbonate, sodium hydrogencarbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

  In particular, it is preferable that the pH-adjusting aqueous solution contains a carbonate because an initial aqueous solution and an aqueous solution containing nickel as a metal component can be mixed in the presence of carbonate ions without separately supplying carbonate ions. The method for supplying the pH-adjusted aqueous solution into the reaction vessel is not particularly limited. For example, a pump capable of controlling the flow rate such as a metering pump while sufficiently stirring the obtained mixed aqueous solution, What is necessary is just to add so that pH value may be kept in a predetermined range.

  And the particle | grains used as the nucleus of a precursor can be produced | generated in the mixed aqueous solution obtained by adding the aqueous solution etc. which contain nickel as a metal component to an initial stage aqueous solution as mentioned above. Whether or not a predetermined amount of nuclei is generated in the mixed aqueous solution can be determined by the amount of the metal salt contained in the mixed aqueous solution.

  Here, an aqueous solution containing nickel as a metal component, an aqueous solution containing cobalt as a metal component, and an aqueous solution containing manganese as a metal component, which are added to the initial aqueous solution in the crystallization step, will be described.

  In the aqueous solution containing nickel as a metal component, the aqueous solution containing cobalt as a metal component, and the aqueous solution containing manganese as a metal component, a metal compound containing each metal component can be contained. That is, for example, in the case of an aqueous solution containing cobalt as a metal component, a metal compound containing cobalt can be included.

  And as a metal compound, it is preferable to use a water-soluble metal compound, and a nitrate, sulfate, hydrochloride, etc. are mentioned as a water-soluble metal compound. Specifically, for example, nickel sulfate, cobalt sulfate, manganese sulfate and the like can be suitably used.

  The aqueous solution containing nickel as the metal component, the aqueous solution containing cobalt as the metal component, and the aqueous solution containing manganese as the metal component are mixed partly or in advance, and the mixed aqueous solution containing metal components It can also be added to the initial aqueous solution side.

  The composition ratio of each metal in the obtained precursor is the same as the composition ratio of each metal in the metal component-containing mixed aqueous solution. For this reason, for example, a dissolved metal is added so that the composition ratio of each metal contained in the mixed aqueous solution containing metal components added to the initial aqueous solution in the crystallization step is equal to the composition ratio of each metal in the precursor to be produced. It is preferable to prepare a mixed aqueous solution containing a metal component by adjusting the ratio of the compound.

  In addition, by mixing a plurality of metal compounds, when specific metal compounds react with each other to generate unnecessary compounds, etc., an aqueous solution containing each metal component is simultaneously made into an initial aqueous solution at a predetermined ratio. It may be added.

  When the aqueous solution containing each metal component is not mixed and added individually to the initial aqueous solution, the composition ratio of each metal contained in the entire precursor solution containing the added metal component is the composition of each metal in the precursor to be generated. It is preferable to prepare an aqueous solution containing each metal component so as to be equal to the ratio.

As described above, the precursor manufactured by the precursor manufacturing method of the present embodiment has a general formula Ni _x Co _y Mn _z M _t CO ₃ (where x + y + z + t = 1, 0.05 ≦ x ≦ 0.3, 0.1 ≦ y ≦ 0.4, 0.55 ≦ z ≦ 0.8, 0 ≦ t ≦ 0.1, M is Mg, Ca, Al, Ti, V, Cr, One or more additional elements selected from Zr, Nb, Mo and W.) and a functional group containing hydrogen.

  That is, in addition to nickel, cobalt, and manganese, an additive element can be further contained.

  For this reason, in the crystallization process, one or more additive elements selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W (hereinafter, simply referred to as “additive elements”) as necessary. An aqueous solution containing (described below) (hereinafter also simply referred to as “an aqueous solution containing an additive element”) can be added to the initial aqueous solution.

  When an aqueous solution containing nickel as a metal component is mixed and added to the initial aqueous solution after the mixed aqueous solution containing the metal component, an aqueous solution containing an additive element is added to and mixed with the mixed aqueous solution containing the metal component. Also good.

  In addition, when an aqueous solution containing nickel as a metal component is added individually to the initial aqueous solution without mixing, an aqueous solution containing an additive element can be individually added to the initial aqueous solution.

  Here, the aqueous solution containing the additive element can be prepared using, for example, a compound containing the additive element. Examples of the compound containing the additive element include titanium sulfate, ammonium peroxotitanate, potassium potassium oxalate, vanadium sulfate, ammonium vanadate, chromium sulfate, potassium chromate, zirconium sulfate, zirconium nitrate, niobium oxalate, molybdenum. Ammonium acid, sodium tungstate, ammonium tungstate and the like can be mentioned, and a compound can be selected according to the element to be added.

  As described above, the additive element is uniformly distributed and / or uniformly coated on the surface of the secondary particles contained in the precursor (hereinafter also simply referred to as “precursor particles”). It is preferable.

  And by adding the aqueous solution containing the above-mentioned additive element to the mixed aqueous solution, the additive element can be uniformly dispersed inside the secondary particles of the precursor particles.

  Moreover, in order to coat | cover the surface of the secondary particle of precursor particle | grains uniformly with an additional element, the coating process which coat | covers with an additional element can be implemented after completion | finish of a crystallization process, for example. The coating process will be described later.

  In the crystallization process, an aqueous solution containing nickel as a metal component is added to and mixed with the initial aqueous solution in the presence of carbonate ions to form a mixed aqueous solution. In the mixed aqueous solution, nuclei are generated and the nuclei are grown. be able to. At this time, the method for supplying carbonate ions is not particularly limited. For example, carbonate ions can be supplied to the mixed aqueous solution by supplying carbon dioxide gas together with an inert gas into the reaction vessel. Also, carbonate ions can be supplied using a carbonate when preparing an initial aqueous solution or a pH-adjusted aqueous solution.

  In the crystallization step, the concentration of ammonium ions in the initial aqueous solution and the mixed aqueous solution is not particularly limited, but is preferably, for example, 0 g / L or more and 20 g / L or less, and particularly preferably maintained at a constant value.

  As explained so far, in the crystallization process, an aqueous solution containing nickel as a metal component is added to the initial aqueous solution in the presence of carbonate ions and mixed to form a mixed aqueous solution, which generates nuclei in the mixed aqueous solution. Can grow.

  At this time, when an aqueous solution containing nickel as a metal component is mixed and added to the initial aqueous solution after the mixed aqueous solution containing the metal component, the concentration of the metal compound in the mixed aqueous solution containing the metal component added to the initial aqueous solution is 1 mol. / L or more and 2.6 mol / L or less is preferable, and 1.5 mol / L or more and 2.2 mol / L or less is more preferable.

  This is because by setting the concentration of the metal compound in the metal component-containing mixed aqueous solution to 1 mol / L or more, a sufficient amount of crystallized matter per reaction tank can be secured and productivity can be increased. On the other hand, by setting the concentration of the metal compound in the metal component-containing mixed aqueous solution to 2.6 mol / L or less, it is possible to more reliably prevent problems such as crystal re-precipitation and clogging of equipment piping. is there.

  The concentration of the metal compound refers to an aqueous solution containing nickel as the metal component, an aqueous solution containing cobalt as the metal component, an aqueous solution containing manganese as the metal component, and in some cases, added to the mixed aqueous solution containing metal components. It means the concentration of the metal compound derived from the aqueous solution containing the added additive element.

  The pH value in the mixed aqueous solution and other ammonium ion concentrations can be measured by a general pH meter and ion meter, respectively.

  In the crystallization step, the temperature of the mixed aqueous solution is preferably maintained at 25 ° C. or higher, and is preferably maintained at 30 ° C. or higher.

  In addition, the upper limit of the temperature of the mixed aqueous solution in the crystallization step is not particularly limited, but may be, for example, 45 ° C. or less.

  This is because, in the crystallization step, by setting the temperature of the mixed aqueous solution to 25 ° C. or higher, the solubility can be increased and nucleation can be easily controlled.

  On the other hand, in the crystallization step, by setting the temperature of the mixed aqueous solution to 45 ° C. or lower, it is possible to prevent the primary crystal from being distorted and to sufficiently increase the tap density when used as the positive electrode active material. is there.

  The particle size of the precursor particles can be controlled by the metal component-containing mixed aqueous solution and the reaction time of the crystallization step.

  That is, in the crystallization step, if the reaction is continued until it grows to a desired particle size, precursor particles having the desired particle size can be obtained. For this reason, it is preferable to implement a crystallization process until the average particle diameter of the secondary particle which the precursor obtained contains becomes 15 micrometers or more and 45 micrometers or less. Specifically, in the crystallization step, it is preferable to set the time so that the average particle size of the secondary particles contained in the obtained precursor is 15 μm or more and 45 μm or less. In particular, it is more preferable to set the time so that the average particle size of the secondary particles contained in the obtained precursor is 15 μm or more and 35 μm or less. For example, it is preferable to set a time for the crystallization step by conducting a preliminary test, obtaining a relationship between the time for the crystallization step and the average particle size of the secondary particles contained in the obtained precursor.

  In the precursor manufacturing method of this embodiment, it is preferable to use an apparatus of a system that does not collect the precursor as a product until the reaction in the crystallization process is completed. Examples of such an apparatus include a normally used batch reaction tank equipped with a stirrer. By adopting such a device, unlike the continuous crystallization device that recovers the product by a general overflow, there is no problem that the growing particles are recovered simultaneously with the overflow liquid, so the particle size distribution is narrow, Particles having a uniform particle size can be obtained, which is preferable.

  In order to control the atmosphere of the reaction tank, it is preferable to use an apparatus capable of controlling the atmosphere, such as a sealed apparatus.

  By using an apparatus capable of controlling the atmosphere of the reaction vessel, the precursor particles can have the structure as described above, and the coprecipitation reaction can be advanced almost uniformly, so that the particle size distribution is excellent. Particles, that is, particles having a narrow particle size distribution range can be obtained.

  In addition, although the example which made the crystallization process one continuous process was shown so far, it is not limited to the form which concerns. For example, the crystallization process can include a nucleation process and a nucleation growth process. That is, the crystallization process can be carried out separately in a nucleation process and a nucleation growth process.

In this case, the crystallization step can have the following steps.
A nucleation step of generating nuclei in a mixed aqueous solution in which an initial aqueous solution, an aqueous solution containing nickel as a metal component, an aqueous solution containing cobalt as a metal component, and an aqueous solution containing manganese as a metal component are mixed.
Nuclear growth process for growing nuclei generated in the nucleation process.
In the nucleation step, the pH value of the mixed aqueous solution is 6.5 or more and 9.0 or less on the basis of the reaction temperature of 40 ° C., and in the nucleus growth step, the pH value of the mixed aqueous solution is 7.0 or more on the basis of the reaction temperature of 40 ° C. It can be controlled to 9.5 or less.

  Hereinafter, the nucleation step and the nucleation growth step will be specifically described with reference to the flowchart shown in FIG. A part of the description overlapping with the above-described crystallization process is omitted.

  One structural example of the flow of the precursor manufacturing method of the present embodiment shown in FIG. 2 will be described below. As shown in FIG. 2, the crystallization step of the precursor manufacturing method of the present embodiment includes (A) a nucleation step and a nucleation step, and then generates precursor particles by a coprecipitation method (B And) a nuclear growth step.

  Thus, by separating the crystallization process from the nucleation process and the nucleation growth process, the time during which the nucleation reaction mainly occurs (nucleation process) and the time during which the nucleation reaction occurs mainly (nucleation growth process) Clearly separated. Thereby, a precursor having a particularly narrow particle size distribution can be obtained. A nuclear disintegration step in which the addition of raw materials is stopped and only stirring is performed may be included between both steps.

The nucleation process and the nucleation growth process will be specifically described below.
(Nucleation process)
First, the nucleation process will be described with reference to FIG.

  As shown in FIG. 2, in the nucleation step, an initial aqueous solution can be prepared by mixing ion-exchanged water (water) and an ammonium ion supplier in a reaction tank. In addition, it is preferable to adjust the pH to 6.5 or more and 9.0 or less by adding an acidic substance such as a sulfate to the initial aqueous solution as necessary, and adjust the pH to 7.0 or more and 8.5 or less. It is more preferable.

  As the ammonium ion supplier, the above-mentioned compounds can be preferably used in the crystallization step.

  At this time, it is preferable to blow an inert gas such as nitrogen gas so that oxygen does not enter the reaction vessel. That is, the inside of the reaction tank is preferably an inert gas atmosphere, for example, a nitrogen gas atmosphere is preferable. As will be described later, it is preferable that the reaction vessel has an inert gas atmosphere even in the nucleus growth step. Therefore, the reaction vessel can be filled with an inert gas atmosphere from the nucleation step to the completion of the nucleus growth step.

  However, when carbon dioxide gas is used as the carbonate ion source as described later, carbon dioxide may be supplied in addition to or in place of the inert gas in the atmosphere in the reaction vessel. it can.

  H / Me, which is a mass ratio of hydrogen contained and metal component Me contained, by performing a nucleation step and an after-mentioned nucleus growth step in an atmosphere containing an inert gas and / or carbon dioxide gas. Is less than 1.60, and the above-described precursor including secondary particles formed by aggregation of a plurality of primary particles can be obtained.

  In the nucleation step, mixing is performed by adding and mixing an aqueous solution containing nickel as the metal component, an aqueous solution containing cobalt as the metal component, and an aqueous solution containing manganese as the metal component into the initial aqueous solution in the reaction vessel. An aqueous solution can be formed.

  During the nucleation step, when an aqueous solution containing nickel as a metal component is added to the initial aqueous solution, the pH value of the obtained mixed aqueous solution is 6.5 to 9.0 based on the reaction temperature of 40 ° C. It is preferably controlled in a range, and more preferably in a range of 7.0 to 8.5. For this reason, the aqueous solution etc. which contain nickel as a metal component can be gradually dripped at initial stage aqueous solution instead of adding at once.

  During the nucleation step, the pH value is preferably controlled within 0.05 above and below the median pH value.

  Further, in order to control the pH of the mixed aqueous solution, a pH adjusting aqueous solution can be dropped together with dropping an aqueous solution containing nickel as a metal component. As the pH adjusting aqueous solution, the aqueous solution described above can be preferably used in the crystallization step.

  The method for supplying the pH-adjusted aqueous solution into the reaction vessel is not particularly limited. For example, a pump capable of controlling the flow rate such as a metering pump while sufficiently stirring the obtained mixed aqueous solution, What is necessary is just to add so that pH value may be kept in a predetermined range.

  And the particle | grains used as the nucleus of a precursor can be produced | generated in the mixed aqueous solution obtained by adding the aqueous solution etc. which contain nickel as a metal component to an initial stage aqueous solution as mentioned above. Whether or not a predetermined amount of nuclei is generated in the mixed aqueous solution can be determined by the amount of the metal salt contained in the mixed aqueous solution.

  Regarding the aqueous solution containing nickel as the metal component, the aqueous solution containing cobalt as the metal component, and the aqueous solution containing manganese as the metal component, which are added to the initial aqueous solution in the nucleation step, the aqueous solution described in the crystallization step is used. It can be preferably used. Further, the initial aqueous solution, the addition method to the mixed aqueous solution, and the like can be carried out in the same manner as in the case of the crystallization step described above, and thus the description thereof is omitted here.

  As described above, the precursor manufactured by the precursor manufacturing method of the present embodiment can further contain an additive element in addition to nickel, cobalt, and manganese.

  For this reason, in the nucleation step, one or more additional elements selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W (hereinafter simply referred to as “additive elements”) as necessary. An aqueous solution containing (described below) (hereinafter also simply referred to as “an aqueous solution containing an additive element”) can be added to the initial aqueous solution.

  Since an aqueous solution containing an additive element that can be suitably used, a method for adding it to an initial aqueous solution or a mixed aqueous solution, etc. have already been described in the crystallization step, description thereof is omitted here.

  As described above, the additive element is uniformly distributed and / or uniformly coated on the surface of the secondary particles contained in the precursor (hereinafter also simply referred to as “precursor particles”). It is preferable.

  And by adding the aqueous solution containing the above-mentioned additive element to the mixed aqueous solution, the additive element can be uniformly dispersed inside the secondary particles of the precursor particles.

  Moreover, in order to coat | cover the surface of the secondary particle of precursor particle | grains uniformly with an additional element, the coating process which coat | covers with an additional element can be implemented after completion | finish of the nucleus growth process mentioned later, for example. The coating process will be described later.

  In the nucleation step, an aqueous solution containing nickel as a metal component is added to and mixed with the initial aqueous solution in the presence of carbonate ions to form a mixed aqueous solution, and nuclei can be generated in the mixed aqueous solution. At this time, the method for supplying carbonate ions is not particularly limited. For example, carbonate ions can be supplied to the mixed aqueous solution by supplying carbon dioxide gas together with an inert gas into the reaction vessel. Also, carbonate ions can be supplied using a carbonate when preparing an initial aqueous solution or a pH-adjusted aqueous solution.

  As explained so far, in the nucleation step, an aqueous solution containing nickel as a metal component is added to the initial aqueous solution in the presence of carbonate ions and mixed to form a mixed aqueous solution, which generates nuclei in the mixed aqueous solution. it can.

  In this case, when an aqueous solution containing nickel as a metal component is mixed and added to the initial aqueous solution after the mixed aqueous solution containing the metal component, the concentration of the metal compound in the mixed aqueous solution containing the metal component added to the initial aqueous solution is particularly limited. However, it is preferable to set the same range as in the case of the crystallization step described above.

  In the nucleation step, the concentration of ammonium ions in the initial aqueous solution and the mixed aqueous solution is not particularly limited, but is preferably, for example, 0 g / L or more and 20 g / L or less, and particularly preferably maintained at a constant value. .

  The pH value in the mixed aqueous solution and other ammonium ion concentrations can be measured by a general pH meter and ion meter, respectively.

  In the nucleation step, the temperature of the mixed aqueous solution is preferably maintained at 25 ° C. or higher, and is preferably maintained at 30 ° C. or higher.

  The upper limit of the temperature of the mixed aqueous solution in the nucleation step is not particularly limited, but can be, for example, 45 ° C. or less.

  This is because when the temperature of the mixed aqueous solution is 25 ° C. or higher in the nucleation step, the solubility can be increased and nucleation can be easily controlled.

  On the other hand, in the nucleation step, when the temperature of the mixed aqueous solution is 45 ° C. or lower, distortion is prevented from occurring in the primary crystal, and when the positive electrode active material is used, the tap density can be sufficiently increased. is there.

  In the nucleation step, the concentration of the crystallized product at the time when the coprecipitation reaction is completed is preferably approximately 30 g / L or more and 200 g / L or less, and more preferably 80 g / L or more and 150 g / L or less. . It is desirable to supply a metal component-containing mixed aqueous solution or the like to the initial aqueous solution so that the concentration of the crystallized product falls within the above range.

  This is because the aggregation of the primary particles in the precursor particles can be sufficiently promoted when the concentration of the crystallized product is 30 g / L or more.

  However, when the concentration of the crystallized product exceeds 200 g / L, the diffusion of the mixed aqueous solution containing metal components in the reaction vessel is not sufficient, and the growth of the precursor particles may be biased. is there.

After completion of the nucleation step, that is, after the addition to the initial aqueous solution (mixed aqueous solution), such as a mixed aqueous solution containing metal components, is completed, stirring of the mixed aqueous solution can be continued to disintegrate the produced nuclei. (Nuclear crushing process). The nuclear disintegration step is preferably performed for 1 minute or longer, more preferably 3 minutes or longer. By carrying out the nuclear disintegration step, it is preferable to prevent the produced nuclei from agglomerating and to more reliably prevent the coarsening of the particle size and the decrease in density inside the particle.
(Nuclear growth process)
Next, the nuclear growth process will be described with reference to FIG.

  In the nucleus growth step, the nuclei generated in the nucleation step can be grown.

  Specifically, for example, as shown in FIG. 2, in the nucleus growth step, first, the pH value of the mixed aqueous solution obtained in the nucleus generation step is, for example, 7.0 or more and 9.5 or less based on the reaction temperature of 40 ° C. Can be adjusted. At this time, the pH value of the mixed aqueous solution is more preferably adjusted to be 7.5 or more and 9.0 or less, and further preferably adjusted to be 7.5 or more and 8.5 or less. The pH value at this time can be adjusted, for example, by adding a pH adjusting solution described later.

  Then, in the nucleation step, the mixed aqueous solution after the nucleation step is an aqueous solution containing nickel as a metal component, an aqueous solution containing cobalt as a metal component, and an aqueous solution containing manganese as a metal component in the presence of carbonate ions. Can be added and mixed.

  In addition, it is preferable that the mixed aqueous solution after a nucleation process here is the mixed aqueous solution which adjusted pH value after the nucleation process as mentioned above.

  The aqueous solution containing nickel as the metal component, the aqueous solution containing cobalt as the metal component, and the aqueous solution containing manganese as the metal component are mixed partially or entirely in the same manner as in the case of the nucleation step. A component-containing mixed aqueous solution may be added to the mixed aqueous solution. Moreover, when a specific metal compound reacts and an unnecessary compound is produced | generated by mixing several metal compounds, the aqueous solution containing each metal component is added separately to mixed aqueous solution, for example. Also good.

  As the aqueous solution containing nickel as the metal component, the aqueous solution containing cobalt as the metal component, and the aqueous solution containing manganese as the metal component, the same aqueous solution as in the nucleation step can be used. Further, the density and the like may be adjusted separately.

  Furthermore, when an aqueous solution containing nickel as a metal component is added to the mixed aqueous solution, an aqueous solution containing an additive element can also be added in the same manner as in the nucleation step. As described above, an aqueous solution containing an additive element may be mixed and added to the metal component-containing mixed aqueous solution. Moreover, when adding the aqueous solution containing each metal component separately to mixed aqueous solution, the aqueous solution containing an additional element can also be added individually to mixed aqueous solution.

  When an aqueous solution containing nickel as a metal component is added to the mixed aqueous solution, the pH value of the obtained mixed aqueous solution is preferably controlled within a predetermined range as described later. For this reason, the aqueous solution containing nickel or the like can be gradually added dropwise to the mixed aqueous solution instead of being added at once. Therefore, an aqueous solution containing these metal components, or a mixed aqueous solution containing the metal components can be supplied to the reaction tank at a constant flow rate.

  When supplying an aqueous solution containing a metal component or a mixed aqueous solution containing the metal component as described above, it is preferable to add a pH-adjusted aqueous solution so that the pH of the mixed aqueous solution can be maintained within a predetermined range. As the pH adjustment aqueous solution, the same pH adjustment aqueous solution as in the nucleation step can be used. In addition, you may adjust a density | concentration etc. separately for pH adjustment aqueous solution.

  In the nucleus growth step, an aqueous solution containing nickel as a metal component can be added to and mixed with the mixed aqueous solution in the presence of carbonate ions. At this time, the method for supplying carbonate ions is not particularly limited. For example, carbonate ions can be supplied to the mixed aqueous solution by supplying carbon dioxide gas into the reaction vessel. Further, for example, carbonate ions can be used to supply carbonate ions when preparing the above-mentioned pH adjustment aqueous solution or the like. In addition, since carbonate ions can be directly supplied into the mixed aqueous solution, it is more preferable to use carbonates to supply carbonate ions when preparing a pH-adjusted aqueous solution.

  In the nucleus growth step, the pH value of the mixed aqueous solution can be adjusted to be 7.0 or more and 9.5 or less on the basis of the reaction temperature of 40 ° C. At this time, the pH value of the mixed aqueous solution is more preferably adjusted to be 7.5 or more and 9.0 or less, and further preferably adjusted to be 7.5 or more and 8.5 or less. For this reason, it is preferable to control so that a mixed aqueous solution may exist in the said range during a nucleus growth process.

  This is because, in the nucleus growth step, it is preferable that the pH value of the mixed aqueous solution is 7.0 or more and 9.5 or less, in particular, the residual impurity cations can be suppressed.

  In the nucleus growth step, it is preferable to adjust and control so that the pH value of the mixed aqueous solution is higher than that in the nucleus generation step described above. For example, it is preferable to adjust the pH value of the mixed aqueous solution to be 0.1 or more higher than the nucleation step on the basis of the reaction temperature of 40 ° C. In the nucleation step, when the pH value of the mixed aqueous solution is set higher than that in the nucleation step, the upper limit of the difference in pH value of the mixed aqueous solution between the nucleation step and the nucleation growth step is not particularly limited. For example, the difference in pH value of the mixed aqueous solution between the nucleation step and the nucleation growth step is preferably 1.0 or less, more preferably 0.5 or less, based on a reaction temperature of 40 ° C.

  Moreover, it is preferable to control so that the fluctuation range of the pH value of the mixed aqueous solution is within 0.05 above and below the median value of the pH value during the nucleus growth step. This is because, by setting the fluctuation range of the pH value of the mixed aqueous solution in the above range, the growth of particles contained in the precursor is made substantially constant, and uniform particles having a narrow particle size distribution range can be obtained.

  The pH value can be controlled by the amount of the initial aqueous solution or the pH adjusting solution added.

  As described above, in the nucleus growth step, a precursor with a small amount of remaining impurities can be obtained by controlling the pH value of the mixed aqueous solution within the above range. Further, since the pH value of the mixed aqueous solution is within the above range and the fluctuation range is reduced, the growth of the precursor particles is made constant, and uniform precursor particles having a narrow particle size distribution range can be obtained. .

  In the nucleus growth step, it is preferable to blow an inert gas such as nitrogen gas so that oxygen does not enter the reaction vessel. That is, the inside of the reaction tank is preferably an inert gas atmosphere, for example, a nitrogen gas atmosphere is preferable. However, when carbon dioxide gas is used as the carbonate ion source, carbon dioxide can be supplied to the atmosphere in the reaction tank in addition to or in place of the inert gas.

  In this way, it is possible to obtain a precursor having a high purity by blowing an inert gas into the reaction tank and preventing oxidation by oxygen in the air. Further, fine crystals can be further aggregated to generate large secondary particles.

  In the nucleus growth step, the ammonium ion concentration in the mixed aqueous solution is preferably 0 g / L or more and 20 g / L or less, particularly preferably maintained at a constant value.

  This is because the nuclei of the precursor particles can be grown uniformly by setting the ammonium ion concentration to 20 g / L or less. Moreover, in the nucleus growth step, the ammonium ion concentration is maintained at a constant value, so that the solubility of metal ions can be stabilized and the nucleus growth of uniform precursor particles can be promoted.

  The lower limit value of the ammonium ion concentration can be appropriately adjusted as necessary, and is not particularly limited. Therefore, the ammonium ion concentration in the mixed aqueous solution is adjusted to be 0 g / L or more and 20 g / L or less by adjusting the supply amount using an ammonium ion supplier when preparing the initial aqueous solution, for example. It is preferable.

  The particle size of the precursor particles can be controlled by the metal component-containing mixed aqueous solution or the reaction time of the nucleus growth step.

  That is, in the nucleus growth step, precursor particles having a desired particle size can be obtained by continuing the reaction until the particle grows to a desired particle size. For this reason, it is preferable to implement a nucleus growth process until the average particle diameter of the secondary particle which the precursor obtained contains becomes 15 micrometers or more and 45 micrometers or less. Specifically, it is preferable to set the time in the nucleus growth step so that the average particle size of the secondary particles contained in the obtained precursor is 15 μm or more and 45 μm or less. In particular, it is more preferable to set the time so that the average particle size of the secondary particles contained in the obtained precursor is 15 μm or more and 35 μm or less. For example, it is preferable to set a time for the nucleus growth step by performing a preliminary test, obtaining a relationship between the time of the nucleus growth step and the average particle size of the secondary particles contained in the obtained precursor.

  In the nucleation step, uniform precursor particles are obtained by adjusting the pH value of the mixed aqueous solution obtained in the nucleation step to be within a predetermined range, and further blowing an inert gas into the reaction vessel. be able to.

  As explained so far, the crystallization process has a particularly narrow particle size distribution by mainly having a time when the nucleation reaction occurs (nucleation process) and a time when the nucleation growth reaction mainly occurs (nucleation growth process). Since a precursor is obtained, it is preferable.

  Moreover, the nucleation step and the nucleation growth step can be performed separately in one reaction tank only by adjusting the pH of the mixed aqueous solution. Therefore, the manufacturing method of the precursor of the present embodiment is easy and suitable for large-scale production even when the nucleation step and the nucleation growth step are performed separately. The target value is extremely high.

  Moreover, the manufacturing method of the precursor of this embodiment can further have a coating process which coat | covers the precursor particle | grains obtained at the crystallization process with an additional element.

  The coating step can be any of the following steps, for example.

  For example, first, an aqueous solution containing an additive element is added to a slurry in which precursor particles are suspended, and the additive element is precipitated on the surface of the precursor particles by a crystallization reaction.

  The slurry in which the precursor particles are suspended is preferably slurried using an aqueous solution containing an additive element. Moreover, when adding the aqueous solution containing the additive element to the slurry in which the precursor particles are suspended, the pH of the mixed aqueous solution of the slurry and the aqueous solution containing the additive element is 5.5 or more and 8.0 or less. It is preferable to control.

  Moreover, a coating process can also be made into the process of spraying and drying the aqueous solution or slurry containing an additional element with respect to precursor particle | grains.

  In addition, the coating step may be a step of spray drying a slurry in which the precursor particles and the compound containing the additive element are suspended.

  Moreover, it can also be set as the process of mixing a precursor particle and the compound containing an additional element by a solid-phase method.

  In addition, about the aqueous solution containing the additional element demonstrated here, the aqueous solution similar to what was demonstrated at the crystallization process can be used. In the coating step, an alkoxide solution containing the additive element may be used instead of the aqueous solution containing the additive element.

  As described above, when an aqueous solution containing an additive element is added to the mixed aqueous solution in the crystallization step, and the surface of the precursor particles is coated with the additional element in the crystallization step, it is added to the mixed aqueous solution in the crystallization step. It is preferable to reduce the amount of additive element ions to be reduced by the amount to be coated. This is because the addition amount of the aqueous solution containing the additive element to be added to the mixed aqueous solution is reduced by the amount to cover, so that the atomic ratio between the additive element contained in the obtained precursor and other metal components can be set as desired. This is because it can be a value.

  As described above, the coating step of coating the surface of the precursor particles with the additive element may be performed on the heated precursor particles after the completion of the crystallization step.

By performing the above crystallization process, a precursor particle aqueous solution which is a slurry containing precursor particles is obtained. And after finishing a crystallization process, a washing | cleaning process and a drying process can be implemented. In addition, when implementing a coating process after a crystallization process, after finishing a coating process, a washing | cleaning process and a drying process can be implemented.
(2) Cleaning Step In the cleaning step, the slurry containing the precursor particles obtained in the crystallization step described above can be cleaned.

  In the washing step, first, the slurry containing the precursor particles can be filtered, then washed with water, and filtered again.

  Filtration may be performed by a commonly used method. For example, a centrifuge or a suction filter is used.

  In addition, the washing with water may be performed by a commonly performed method, as long as excess raw materials contained in the precursor can be removed.

The water used in the water washing is preferably water having as little impurity content as possible, and more preferably pure water, in order to prevent contamination of impurities.
(3) Drying Step In the drying step, the precursor particles washed in the washing step can be dried.
First, in the drying step, for example, the dried precursor particles can be dried at a drying temperature of 100 ° C. or higher and 230 ° C. or lower.

  A precursor can be obtained after a drying process.

  According to the method for producing a precursor of the present embodiment, a precursor capable of forming a positive electrode active material for a non-aqueous electrolyte secondary battery containing dense particles can be obtained.

  In addition, in the precursor manufacturing method of the present embodiment, the crystal size of the precursor obtained by the crystallization reaction can be controlled.

  Therefore, according to the precursor manufacturing method of the present embodiment, it is possible to obtain a precursor having a small primary particle size, high secondary particle size uniformity, and high density (tap density). it can.

[Positive electrode active material for non-aqueous electrolyte secondary battery]
Next, a configuration example of the positive electrode active material for a non-aqueous electrolyte secondary battery according to the present embodiment (hereinafter also simply referred to as “positive electrode active material”) will be described.

  The positive electrode active material of this embodiment is related with the positive electrode active material for nonaqueous electrolyte secondary batteries containing a lithium metal complex oxide.

The lithium metal composite oxide has the general formula Li _{1 + α} Ni _x Co _y Mn _z M _t O ₂ (0.25 ≦ α ≦ 0.55, x + y + z + t = 1, 0.05 ≦ x ≦ 0.3, 0.1 ≦ y ≦ 0.4, 0.55 ≦ z ≦ 0.8, 0 ≦ t ≦ 0.1, M is an additive element, Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, One or more elements selected from W).

  And the positive electrode active material of this embodiment contains the secondary particle which the several primary particle aggregated, and the average particle diameter of this secondary particle can be 12 micrometers or more and 40 micrometers or less. In addition, among the secondary particles contained in the positive electrode active material of the present embodiment, the number ratio of dense secondary particles having an internal porosity of 3% or less can be set to 65% or more.

The positive electrode active material of the present embodiment is a lithium metal composite oxide in which two types of layered compounds represented by Li ₂ M1O ₃ and LiM2O ₂ are dissolved, and more specifically, a lithium-excess nickel cobalt manganese composite oxide Particles can be included. In addition, the positive electrode active material of this embodiment can also be comprised from the said lithium metal complex oxide.

  In the above formula, M1 is a metal element containing at least Mn adjusted to be tetravalent on average, and M2 is a metal element containing at least Ni, Co, and Mn adjusted to be trivalent on average. is there.

It is assumed that the composition ratio of Ni, Co, and Mn shown in the above-described precursor is established as M1 + M2. Moreover, since the abundance ratio of Li ₂ M1O ₃ and LiM2O ₂ is excess of lithium, Li ₂ M1O ₃ is not 0%.

  The positive electrode active material of this embodiment can contain secondary particles in which primary particles are aggregated. And among the secondary particles which the positive electrode active material of this embodiment contains, the number ratio of the dense secondary particle (dense particle) which has a dense structure to the center part of a secondary particle can be made high. Thus, the tap density can be increased by increasing the number ratio of the dense particles among the secondary particles contained in the positive electrode active material. That is, a high-density positive electrode active material can be obtained. Specifically, the tap density of the positive electrode active material of this embodiment is preferably 2.0 g / cc or more, and more preferably 2.1 g / cc or more.

  The positive electrode active material of this embodiment preferably contains dense secondary particles having a porosity of 3% or less inside the secondary particles. Moreover, it is preferable that the positive electrode active material of this embodiment contains 65% or more of such dense secondary particles among the contained secondary particles in terms of the number. The porosity of the dense secondary particles can be calculated by, for example, observing the cross-sectional structure of the positive electrode active material with an SEM and performing image processing or the like. The ratio of the number of dense secondary particles is, for example, by observing the cross-sectional structure of a plurality of secondary particles of, for example, 100 positive electrode active materials by SEM, and counting the percentage of dense secondary particles. Can be obtained. In addition, the upper limit of the number ratio of the dense particles among the secondary particles contained in the positive electrode active material of the present embodiment is not particularly limited, and can be, for example, 100% or less.

  Furthermore, the average particle diameter of the secondary particles of the positive electrode active material of this embodiment is preferably 12 μm or more, and more preferably 14 μm or more. This is because the packing density of the positive electrode can be increased and the battery capacity per volume can be increased by setting the average particle size of the secondary particles to 12 μm or more.

  In particular, in the positive electrode active material of the present embodiment, the dense particles among the secondary particles contained in the positive electrode active material are also high. The density can be increased. That is, a high-density positive electrode active material can be obtained.

The average particle size of the secondary particles of the positive electrode active material of the present embodiment is preferably 40 μm or less, and more preferably 30 μm or less. This is because, by setting the average particle size of the secondary particles to 40 μm or less, the specific surface area can be increased and the interface with the electrolyte can be sufficiently secured, so that the resistance of the positive electrode is suppressed and the output characteristics of the battery are improved. Because you can.
[Method for producing positive electrode active material for non-aqueous electrolyte secondary battery]
Next, one structural example of the method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery of the present embodiment (hereinafter also simply referred to as “method for producing a positive electrode active material”) will be described.

  The method for producing the positive electrode active material according to the present embodiment is not particularly limited as long as the positive electrode active material can be produced so as to have the particle structure of the positive electrode active material described above. This is preferable because the active material can be produced more reliably.

  The manufacturing method of the positive electrode active material of this embodiment can have the following processes.

A heat treatment step of heat-treating the positive electrode active material precursor for a non-aqueous electrolyte secondary battery obtained by the above-described method for producing a positive electrode active material precursor for a non-aqueous electrolyte secondary battery at a temperature of 80 ° C to 600 ° C.
A mixing step in which a lithium compound is added to and mixed with the particles obtained by the heat treatment step to form a lithium mixture.
A firing step of firing the lithium mixture at a temperature of 600 ° C. or higher and 1000 ° C. or lower in an oxidizing atmosphere.

Hereinafter, each step will be described.
(1) Heat treatment step In the heat treatment step, the above-described precursor can be heat treated at a temperature of 80 ° C or higher and 600 ° C or lower. By performing the heat treatment, moisture contained in the precursor can be removed, and variation in the ratio of the number of metal atoms and the number of lithium atoms in the finally obtained positive electrode active material can be prevented.

  It should be noted that all the precursors need not be converted into nickel-cobalt-manganese composite oxides, as long as moisture can be removed to such an extent that variations in the number of metal atoms and the number of lithium atoms in the positive electrode active material do not occur. However, in order to reduce the above-mentioned variation, it is preferable to convert the precursor to all composite oxide particles by setting the heating temperature to 500 ° C. or higher.

  The reason why the heat treatment temperature is set to 80 ° C. or higher in the heat treatment step is that when the heat treatment temperature is less than 80 ° C., excess moisture in the precursor cannot be removed and the above variation may not be suppressed.

  On the other hand, the heat treatment temperature is set to 600 ° C. or less because if the heat treatment temperature exceeds 600 ° C., the particles may be sintered by roasting and composite oxide particles having a uniform particle size may not be obtained. . The dispersion | variation can be suppressed by calculating | requiring beforehand the metal component contained in the precursor corresponding to heat processing conditions by analysis, and determining ratio with a lithium compound.

  The heat treatment atmosphere is not particularly limited and may be a non-reducing atmosphere, but is preferably performed in an air stream that can be easily performed.

  In addition, the heat treatment time is not particularly limited, but if it is less than 1 hour, the excess moisture of the precursor may not be sufficiently removed, and therefore it is preferably at least 1 hour or more and more preferably 2 hours or more and 15 hours or less.

The equipment used for the heat treatment is not particularly limited as long as the precursor can be heated in a non-reducing atmosphere, preferably in an air stream, and an electric furnace that does not generate gas is suitable. Used.
(2) Mixing step The mixing step is a step of forming a lithium mixture by adding and mixing a lithium compound to the heat-treated particles obtained by heating in the heat treatment step.

  The heat-treated particles obtained by heat treatment in the heat treatment step include nickel cobalt manganese carbonate composite particles and / or nickel cobalt manganese composite oxide particles.

  The heat-treated particles and the lithium compound are the number of atoms of metals other than lithium in the lithium mixture, that is, the sum of the number of atoms of nickel, cobalt, manganese and additive elements (Me) and the number of atoms of lithium (Li). It is preferable to mix so that ratio (Li / Me) may be 1.1 or more and 1.6 or less. At this time, it is more preferable to mix so that Li / Me is 1.25 or more and 1.55 or less.

  That is, since Li / Me does not change before and after the firing step, Li / Me mixed in this mixing step becomes Li / Me in the positive electrode active material, so that Li / Me in the lithium mixture is to be obtained. To be the same as Li / Me.

  The lithium compound used to form the lithium mixture is not particularly limited, but is preferably one or more selected from, for example, lithium hydroxide, lithium nitrate, and lithium carbonate because it is easily available. Can be used.

  In particular, in view of ease of handling and quality stability, it is more preferable to use at least one selected from lithium hydroxide and lithium carbonate as the lithium compound used in forming the lithium mixture.

For mixing, a general mixer can be used. For example, a shaker mixer, a Laedige mixer, a Julia mixer, a V blender, or the like may be used.
(3) Firing step The firing step is a step in which the lithium mixture obtained in the mixing step is fired to obtain a positive electrode active material. When the mixed powder is fired in the firing step, lithium in the lithium compound diffuses into the heat-treated particles, so that a lithium nickel cobalt manganese composite oxide is formed.

  The firing temperature of the lithium mixture at this time is not particularly limited, but is preferably 600 ° C. or higher and 1000 ° C. or lower, and more preferably 800 ° C. or higher and 900 ° C. or lower.

  This is because when the firing temperature is set to 600 ° C. or higher, the diffusion of lithium into the heat-treated particles is sufficiently promoted, and the remaining of excess lithium and unreacted particles is suppressed and used in a battery. This is because sufficient battery characteristics can be obtained.

  However, when the firing temperature exceeds 1000 ° C., intense sintering occurs between the composite oxide particles and abnormal grain growth may occur. Such a positive electrode active material has a reduced specific surface area. When used for the above, there is a risk that the resistance of the positive electrode increases and the battery capacity decreases.

  In addition, from the viewpoint of uniformly performing the reaction between the heat-treated particles and the lithium compound, it is preferable to raise the temperature to the above temperature with a temperature increase rate of 3 ° C./min to 10 ° C./min.

  Furthermore, the reaction can be performed more uniformly by maintaining at a temperature near the melting point of the lithium compound for about 1 hour to 5 hours. When the temperature is maintained near the melting point of the lithium compound, the temperature can be raised to a predetermined firing temperature.

  Of the firing time, the holding time at the firing temperature is preferably 2 hours or more, and more preferably 4 hours or more and 24 hours or less.

  This is because the generation of the lithium nickel cobalt manganese composite oxide can be sufficiently promoted by holding at the firing temperature for 2 hours or more.

  After completion of the holding time at the firing temperature, there is no particular limitation. However, when the lithium mixture is loaded on the sagger and baked, the rate of descent is 2 ° C./min to 10 ° C. to suppress deterioration of the sachet. It is preferable that the atmosphere is cooled to 200 ° C. or lower as the temperature / ° C. or lower.

  The atmosphere during firing is preferably an oxidizing atmosphere, more preferably an oxygen concentration of 18% by volume to 100% by volume, and a mixed atmosphere of oxygen and an inert gas having the oxygen concentration. Is particularly preferred. That is, the firing is preferably performed in the atmosphere or an oxygen-containing gas.

  This is because the crystallinity of the lithium nickel cobalt manganese composite oxide can be sufficiently increased by setting the oxygen concentration to 18% by volume or more.

  Considering battery characteristics in particular, it is preferably performed in an oxygen stream.

  The furnace used for firing is not particularly limited as long as the lithium mixture can be heated in the atmosphere or an oxygen-containing gas. However, from the viewpoint of maintaining a uniform atmosphere in the furnace, gas generation is not caused. No electric furnace is preferred. In addition, either a batch type or continuous type furnace can be used.

  When lithium hydroxide or lithium carbonate is used as the lithium compound, it is preferably calcined after the mixing step and before the firing step. The calcination temperature is lower than the firing temperature and is preferably 350 ° C. or higher and 800 ° C. or lower, and more preferably 450 ° C. or higher and 780 ° C. or lower.

  The calcination time is preferably about 1 hour to 10 hours, more preferably 3 hours to 6 hours.

  The calcination is preferably carried out while maintaining the calcination temperature. That is, it is preferable to calcine at the reaction temperature between lithium hydroxide or lithium carbonate and the heat-treated particles.

  When calcination is performed, lithium is sufficiently diffused into the heat-treated particles, and a uniform lithium nickel cobalt manganese composite oxide can be obtained, which is preferable.

  The particles of the lithium nickel cobalt manganese composite oxide obtained by the firing step may be aggregated or slightly sintered.

  In this case, it may be crushed. Thereby, the positive electrode active material of this embodiment containing a lithium nickel cobalt manganese composite oxide can be obtained.

Note that pulverization means that mechanical energy is applied to an aggregate composed of a plurality of secondary particles generated by sintering necking between secondary particles during firing, and the secondary particles themselves are hardly destroyed. This is an operation of separating the secondary particles and loosening the aggregates.
[Nonaqueous electrolyte secondary battery]
Next, a configuration example of the non-aqueous electrolyte secondary battery of the present embodiment will be described. The non-aqueous electrolyte secondary battery of this embodiment can have a positive electrode using the positive electrode active material described above.

  First, the structure of the nonaqueous electrolyte secondary battery of this embodiment will be described.

  The nonaqueous electrolyte secondary battery of the present embodiment (hereinafter also simply referred to as “secondary battery”) is a general nonaqueous electrolyte secondary battery except that the positive electrode active material described above is used as the positive electrode material. And substantially the same structure.

  The secondary battery of this embodiment can have, for example, a structure including a case, and a positive electrode, a negative electrode, a nonaqueous electrolyte, and a separator housed in the case.

  More specifically, the secondary battery of the present embodiment can have an electrode body in which a positive electrode and a negative electrode are stacked via a separator. Then, the electrode body is impregnated with a non-aqueous electrolyte, and the current is collected between the positive electrode current collector of the positive electrode and the positive electrode terminal communicating with the outside, and between the negative electrode current collector of the negative electrode and the negative electrode terminal communicating with the outside, respectively. It can be connected with a lead or the like and sealed in a case.

  In addition, it cannot be overemphasized that the structure of the secondary battery of this embodiment is not limited to the said example, Moreover, the external shape can employ | adopt various shapes, such as a cylinder shape and a laminated form.

(Positive electrode)
First, the positive electrode that is a feature of the secondary battery of this embodiment will be described. The positive electrode is a sheet-like member, and is formed by applying and drying the above-described positive electrode mixture paste containing the positive electrode active material on the surface of a current collector made of aluminum foil, for example.

  In addition, a positive electrode is suitably processed according to the battery to be used. For example, a cutting process for forming an appropriate size according to a target battery, a pressure compression process using a roll press or the like to increase the electrode density, and the like are performed.

  The positive electrode mixture paste can be formed by adding a solvent to the positive electrode mixture and kneading. The positive electrode mixture can be formed by mixing the above-described positive electrode active material in powder form, a conductive material, and a binder.

  The conductive material is added to give an appropriate conductivity to the electrode. The conductive material is not particularly limited, and for example, graphite (natural graphite, artificial graphite, expanded graphite, and the like), and carbon black materials such as acetylene black and ketjen black can be used.

  The binder plays a role of tethering the positive electrode active material particles. The binder used for this positive electrode mixture is not particularly limited. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), fluorine rubber, ethylene propylene diene rubber, styrene butadiene, cellulose resin, Polyacrylic acid or the like can be used.

  In addition, activated carbon etc. may be added to a positive electrode compound material, and the electric double layer capacity | capacitance of a positive electrode can be increased by adding activated carbon etc.

  The solvent dissolves the binder and disperses the positive electrode active material, the conductive material, activated carbon, and the like in the binder. The solvent is not particularly limited, and for example, an organic solvent such as N-methyl-2-pyrrolidone can be used.

  Moreover, the mixing ratio of each substance in the positive electrode mixture paste is not particularly limited. For example, when the solid content of the positive electrode mixture excluding the solvent is 100 parts by mass, the content of the positive electrode active material is not less than 60 parts by mass and not more than 95 parts by mass as in the case of the positive electrode of a general nonaqueous electrolyte secondary battery. The content of the material can be 1 part by mass or more and 20 parts by mass or less, and the content of the binder can be 1 part by mass or more and 20 parts by mass or less.

(Negative electrode)
The negative electrode is a sheet-like member formed by applying a negative electrode mixture paste to the surface of a metal foil current collector such as copper and drying it. The negative electrode is formed by substantially the same method as the positive electrode, although the components constituting the negative electrode mixture paste, the composition thereof, and the current collector material are different. Is done.

  The negative electrode mixture paste is a paste obtained by adding an appropriate solvent to a negative electrode mixture in which a negative electrode active material and a binder are mixed.

  As the negative electrode active material, for example, a material containing lithium such as metallic lithium or a lithium alloy, or an occlusion material that can occlude and desorb lithium ions can be employed.

  The occlusion material is not particularly limited, and for example, natural graphite, artificial graphite, an organic compound fired body such as a phenol resin, and a carbon material powder such as coke can be used. When such an occlusion material is employed as the negative electrode active material, a fluorine-containing resin such as PVDF can be used as the binder, as with the positive electrode, and as a solvent for dispersing the negative electrode active material in the binder, An organic solvent such as N-methyl-2-pyrrolidone can be used.

(Separator)
The separator is disposed so as to be sandwiched between the positive electrode and the negative electrode, and has a function of separating the positive electrode and the negative electrode and holding the electrolyte. As such a separator, for example, a thin film such as polyethylene or polypropylene and a film having a large number of fine pores can be used. However, the separator is not particularly limited as long as it has the above function.

(Non-aqueous electrolyte)
The non-aqueous electrolyte is obtained by dissolving a lithium salt as a supporting salt in an organic solvent.

  Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate; chain carbonates such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, and dipropyl carbonate; Ether compounds such as methyltetrahydrofuran and dimethoxyethane; sulfur compounds such as ethyl methyl sulfone and butane sultone; phosphorus compounds such as triethyl phosphate and trioctyl phosphate alone, or a mixture of two or more Can be used.

As the supporting salt, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiN (CF ₃ SO ₂ ) ₂ , and complex salts thereof can be used.

  The non-aqueous electrolyte may contain a radical scavenger, a surfactant, a flame retardant, etc. for improving battery characteristics.

(Characteristics of the non-aqueous electrolyte secondary battery of this embodiment)
The non-aqueous electrolyte secondary battery of the present embodiment can have the above-described configuration, for example, and has a positive electrode using the above-described positive electrode active material, so that a high initial discharge capacity and a low positive electrode resistance are obtained. High capacity and high output.

(Use of secondary battery of this embodiment)
Since the secondary battery of this embodiment has the above properties, it is suitable for the power source of small portable electronic devices (such as notebook personal computers and mobile phone terminals) that always require high capacity.

  Further, the secondary battery of the present embodiment is also suitable for a battery as a motor driving power source that requires a high output. When the battery size increases, it becomes difficult to ensure safety, and an expensive protection circuit is indispensable. However, the secondary battery of this embodiment has excellent safety, so ensuring safety Not only becomes easy, but also an expensive protection circuit can be simplified and the cost can be reduced. And since it can be reduced in size and increased in output, it is suitable as a power source for transportation equipment subject to restrictions on the mounting space.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

Hereinafter, sample preparation conditions and evaluation results in each example and comparative example will be described.
[Example 1]
1. Production and Evaluation of Precursor First, a precursor was produced by the following procedure.

  Throughout all the examples and comparative examples, the Wako Pure Chemical Industries, Ltd. reagent grade samples are used for the preparation of the precursor, the positive electrode active material, and the secondary battery unless otherwise specified.

In the crystallization process, the following nucleation process in which the pH of the mixed aqueous solution was different and the nucleation growth process were performed separately.
(Nucleation process)
(1) Preparation of initial aqueous solution First, in a reaction tank (5 L), water is added to an amount of about 1.2 L, and the temperature in the tank is set to 40 ° C. while stirring. The mixed aqueous solution was controlled to 40 ° C. in the crushing step and the nucleus growth step.

  Then, an appropriate amount of 25% by mass ammonia water was added to the water in the reaction vessel to adjust the ammonium ion concentration in the initial aqueous solution to 5 g / L.

  64% sulfuric acid was further added to the initial aqueous solution to adjust the pH to 7.4.

Then, nitrogen gas was supplied from the nitrogen gas cylinder at 5 L / min into the reaction tank, and the inside of the tank was purged to create a nitrogen atmosphere. Note that the reaction vessel is maintained in a nitrogen atmosphere until the nucleus growth step is completed.
(2) Preparation of metal component-containing mixed aqueous solution Next, nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved in water to prepare a metal component-containing mixed aqueous solution having a metal ion concentration of 2.0 mol / L. In this metal component-containing mixed aqueous solution, the element molar ratio of each metal was adjusted to be Ni: Co: Mn = 0.165: 0.165: 0.67.
(3) Adjustment of pH adjustment aqueous solution Sodium carbonate and ammonium carbonate were dissolved in water to prepare a pH adjustment aqueous solution having a carbonate ion concentration of 2.2 mol / L. The sodium carbonate and ammonium carbonate in the pH-adjusted aqueous solution were added so that the molar ratio was 9: 2.
(4) Addition and mixing of metal component-containing mixed aqueous solution to initial aqueous solution Add metal component-containing mixed aqueous solution to the initial aqueous solution in the reaction vessel at 10.3 ml / min. To obtain a mixed aqueous solution.

  When adding the metal component-containing mixed aqueous solution, a pH adjusting aqueous solution is added at the same time so that the pH value of the mixed aqueous solution in the reaction tank (reaction temperature 40 ° C. standard) becomes 7.4 (nucleation pH value). The nucleation step was carried out by crystallization for 4 minutes.

In the nucleation step, the pH value was controlled by adjusting the supply flow rate of the pH adjusted aqueous solution with a pH controller, and the fluctuation range of the pH value of the mixed aqueous solution was within the range of 0.05 above and below the set value.
(5) Nuclear crushing step After the addition of the metal component-containing mixed aqueous solution and the pH adjusting aqueous solution was completed, stirring was continued for 5 minutes to crush the nucleus.
(Nuclear growth process)
In the nucleation step, the same metal component-containing mixed aqueous solution and pH adjustment aqueous solution as in the nucleation step were used. The experimental procedure of the nuclear growth process will be described below.
(1) Adjustment of pH of mixed aqueous solution In the nuclear growth step, first, a pH adjusted aqueous solution was added to the mixed aqueous solution obtained in the nucleation step to adjust the pH value to 7.6 (liquid temperature 40 ° C. standard).
(2) Addition of metal component-containing mixed aqueous solution to mixed aqueous solution, mixing To the mixed aqueous solution after pH adjustment, 10.3 ml / min. The ratio was added.

  At this time, the addition amounts of the metal component-containing mixed aqueous solution and the pH adjusting aqueous solution were controlled so that the pH value of the mixed aqueous solution was 7.6 based on the reaction temperature of 40 ° C.

  After this state was continued for 196 minutes, stirring was stopped and crystallization was terminated.

  And the product obtained by the nucleus growth process was washed with water, filtered, and dried to obtain precursor particles (washing and drying process).

  In the nuclear growth step, the pH value was controlled by adjusting the supply flow rate of the pH adjusting aqueous solution with a pH controller, and the fluctuation range of the pH value of the mixed aqueous solution was within a range of 0.05 above and below the set value. .

  In the nucleation step and the nucleation growth step, the ammonium ion concentration in the mixed aqueous solution was maintained at 5 g / L.

(Evaluation of precursor)
The obtained precursor was dissolved with an inorganic acid and then subjected to chemical analysis by ICP emission spectroscopy. As a result, the composition was Ni: Co: Mn = 16.3 at%: 16.7 at%: 67.0 at%. It was confirmed that the carbonate was composed of Furthermore, using an elemental analyzer (Model: FlashEA 1112 manufactured by Thermo Fisher Scientific), the element amount of hydrogen (H) is measured, and a substance amount ratio H / Me with metal (Ni + Co + Mn) is calculated to be 1.53. It was confirmed that Moreover, it has confirmed that it had a functional group containing hydrogen.

Further, the particles of the precursor, the average particle diameter d _50, a laser diffraction scattering particle size distribution analyzer (manufactured by Nikkiso Co., Ltd., Microtrac HRA) result of measurement with a mean particle size is 16.4μm I was able to confirm.

Similarly, d ₉₀ and d ₁₀ were measured with a laser diffraction / scattering particle size distribution measuring apparatus, and the result was used to calculate (d ₉₀ −d ₁₀ ) / average particle size, which indicates the spread of the particle size distribution. .43 was confirmed.

Next, SEM (manufactured by Hitachi High-Technologies Corporation, Scanning Electron Microscope S-4700) observation (magnification: 1000 times) of the obtained precursor particles was performed. As a result, the obtained precursor particles were primary. It was confirmed that the particles contained secondary particles formed by aggregation of the particles, the secondary particles were substantially spherical, and the particle sizes were almost uniform. In the case of such a shape, the sphericity of the precursor particles shown in Table 2 is judged as ◯.
2. Production and Evaluation of Positive Electrode Active Material Next, production and evaluation of the positive electrode active material were performed using the obtained precursor.

(Manufacture of positive electrode active material)
The precursor was heat-treated at 500 ° C. for 2 hours in an air stream (oxygen: 21 vol%) to convert to the composite oxide particles as heat-treated particles, and recovered.

  Next, a lithium compound was added to and mixed with the heat-treated particles to form a lithium mixture.

  Specifically, lithium carbonate was weighed so that Li / Me = 1.5 of the obtained lithium mixture and mixed with the heat-treated particles to prepare a lithium mixture.

  Mixing was performed using a shaker mixer apparatus (manufactured by Willy et Bacofen (WAB), TURBULA Type T2C).

  The obtained lithium mixture was calcined in the atmosphere (oxygen: 21% by volume) at 500 ° C. for 5 hours, then calcined at 800 ° C. for 2 hours, cooled, and crushed to obtain a positive electrode active material. .

Note that the composition of the obtained positive electrode active material is expressed as Li _1.5 Ni _0.163 Co _0.167 Mn _0.67 O ₂ .

(Evaluation of positive electrode active material)
When the particle size distribution of the obtained positive electrode active material was measured by the same method as in the case of the precursor particles, it was confirmed that the average particle size was 14.4 μm.

  Moreover, cross-sectional SEM observation of the positive electrode active material was performed.

  In performing SEM observation of the cross section of the positive electrode active material, secondary particles of a plurality of positive electrode active material particles were embedded in a resin, and the cross section polisher process was performed to enable observation of the cross section of the particles. .

  FIG. 3 shows a cross-sectional SEM observation result of the positive electrode active material. In addition, the particle A in FIG. 3 has shown the dense particle, and the particle B has shown the porous particle which has a space | gap inside a particle | grain.

  As shown in FIG. 3, it was confirmed that the obtained positive electrode active material was substantially spherical. In this case, the sphericity is evaluated as ◯ in Table 3. Moreover, it was confirmed that the inside of the secondary particles were dense particles.

  In addition, 100 or more particles of these cross-sectional SEM images were observed, and the porosity of the secondary particles was calculated using image analysis software (Development software of National Institutes of Health, ImageJ). As a result, the ratio of the number of dense particles was 65%. The fine particles mean secondary particles having a porosity of 3% or less. The average porosity of the fine particles was measured using image analysis software and found to be 3%.

  Furthermore, when the tap density was measured, it was confirmed that it was 2.1 g / cc.

  The tap density was measured after the obtained positive electrode active material was filled into a 20 ml graduated cylinder, and then the graduated cylinder was closely packed by a method in which free fall from a height of 2 cm was repeated 500 times.

Further, when the specific surface area of the obtained positive electrode active material was determined by a flow method gas adsorption method specific surface area measurement device (manufactured by Yuasa Ionics Co., Ltd., Multisorb), it was confirmed to be 4.5 m ² / g.

(Manufacture of secondary batteries)
Using the obtained positive electrode active material, a 2032 type coin-type battery was prepared and evaluated.

  The configuration of the manufactured coin battery will be described with reference to FIG. FIG. 4 schematically shows a cross-sectional configuration diagram of the coin-type battery.

  As shown in FIG. 4, the coin-type battery 10 includes a case 11 and an electrode 12 accommodated in the case 11.

  The case 11 has a positive electrode can 111 that is hollow and open at one end, and a negative electrode can 112 that is disposed in the opening of the positive electrode can 111, and the negative electrode can 112 is disposed in the opening of the positive electrode can 111. A space for accommodating the electrode 12 is formed between the negative electrode can 112 and the positive electrode can 111.

  The electrode 12 includes a positive electrode 121, a separator 122, and a negative electrode 123, which are stacked in this order, so that the positive electrode 121 is in contact with the inner surface of the positive electrode can 111 and the negative electrode 123 is in contact with the inner surface of the negative electrode can 112. In the case 11.

  The case 11 includes a gasket 113, and the gasket 113 is fixed so as to maintain an electrically insulated state between the positive electrode can 111 and the negative electrode can 112. In addition, the gasket 113 has a function of sealing the gap between the positive electrode can 111 and the negative electrode can 112 and blocking the inside and outside of the case 11 in an airtight and liquidtight manner.

  This coin-type battery 10 was produced as follows. First, 52.5 mg of the obtained positive electrode active material, 15 mg of acetylene black, and 7.5 mg of polytetrafluoroethylene resin (PTFE) were mixed with a solvent (N-methyl-2-pyrrolidone), and the diameter was 11 mm at a pressure of 100 MPa. The positive electrode 121 was produced by press molding to a thickness of 100 μm. The produced positive electrode 121 was dried in a vacuum dryer at 120 ° C. for 12 hours. Using the positive electrode 121, the negative electrode 123, the separator 122, and the electrolytic solution, the coin-type battery 10 was manufactured in a glove box in an Ar atmosphere in which the dew point was controlled at -80 ° C.

The negative electrode 123 was a negative electrode sheet punched into a disk shape having a diameter of 14 mm and having a mean particle size of about 20 μm and polyvinylidene fluoride applied to a copper foil. The separator 122 was a polyethylene porous film with a film thickness of 25 μm. As the electrolytic solution, an equivalent mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) using 1M LiClO ₄ as a supporting electrolyte (manufactured by Toyama Pharmaceutical Co., Ltd.) was used.

(Battery evaluation)
The initial discharge capacity for evaluating the performance of the obtained coin-type battery 10 was defined as follows.

  The initial discharge capacity is left for about 24 hours after the coin-type battery 10 is manufactured, and after the open circuit voltage OCV (open circuit voltage) is stabilized, the current density with respect to the positive electrode is 0.05 C (270 mAh / g is 1 C). ) To a cut-off voltage of 4.65 V, the capacity when discharged to a cut-off voltage of 2.35 V after a pause of 1 hour was defined as the initial discharge capacity.

  When a battery evaluation was performed on a coin-type battery having a positive electrode formed using the positive electrode active material, the initial discharge capacity was 220 mAh / g. The energy density, which is the product of the initial discharge capacity and the tap density, was 462 mAh / cc.

  Table 1 summarizes the manufacturing conditions of this example, Table 2 shows the characteristics of the precursor obtained in this example, and the characteristics of the positive electrode active material and the coin-type battery manufactured using this positive electrode active material. Table 3 shows the initial discharge capacity. The same contents are shown in the same table for the following examples and comparative examples.

[Example 2]
The crystallization process is not divided into a nucleation process and a nucleation growth process, and is a single process, and the mixed aqueous solution pH between the initial aqueous solution and the crystallization process is 7.6. That is, the pH of the mixed aqueous solution was controlled to be 7.6 between the nucleation step and the nucleation growth step.

  In each step, the pH value was controlled by adjusting the supply flow rate of the pH adjusting aqueous solution with a pH controller, and the fluctuation range of the pH value of the mixed aqueous solution was in the range of 0.05 above and below the set value.

  Except for the above, a precursor, a positive electrode active material, and a secondary battery were produced and evaluated in the same manner as in Example 1. The results are shown in Tables 1 to 3.

In addition, the composition of the obtained positive electrode active material is expressed as Li _1.5 Ni _0.159 Co _0.166 Mn _0.675 O ₂ .

[Comparative Example 1]
The same procedure as in Example 1 was performed except that the pH of the mixed aqueous solution in the initial aqueous solution and the nucleation step was changed to 6.4 and the pH of the mixed aqueous solution in the nucleus growth step was changed to 7.4. A precursor, a positive electrode active material, and a secondary battery were prepared and evaluated. The results are shown in Tables 1 to 3.

  In each step, the pH value was controlled by adjusting the supply flow rate of the pH adjusting aqueous solution with a pH controller, and the fluctuation range of the pH value of the mixed aqueous solution was in the range of 0.05 above and below the set value.

  The obtained positive electrode active material was subjected to cross-sectional SEM observation in the same manner as in Example 1.

  FIG. 5A and FIG. 5B show cross-sectional images of the particles. FIG. 5B shows an enlarged view of the particle surrounded by the broken line in FIG.

  As shown in FIGS. 5 (A) and 5 (B), it was confirmed that all of the obtained positive electrode active materials contained dense particles having a porosity of 3% or less. However, as shown in Table 3, the average particle size was as small as 8.2 μm, and the tap density was inferior to that of the example as shown in Table 3.

  For the precursors of Examples 1 and 2, it was confirmed from the results in Table 2 that the carbonate of the target composition was obtained. Moreover, it has confirmed that the precursor contains the functional group containing hydrogen also in any Example. In any of the examples, it was also confirmed that the precursor contained secondary particles formed by aggregating a plurality of primary particles.

  In addition, from the results of Table 3, the positive electrode active material prepared from the precursors obtained in Examples 1 and 2 includes secondary particles in which a plurality of primary particles are aggregated, and the secondary particles are the number ratio of dense particles. It was also confirmed that the dense particles had a low average porosity. Therefore, in Examples 1 and 2, it was confirmed that a high-density positive electrode active material and its precursor could be formed.

  On the other hand, in Comparative Example 1, it was confirmed from the results in Table 2 that the obtained precursor had an average particle size as small as 8.8 μm. Moreover, it was confirmed that the obtained precursor had a large (d90-d10) / average particle size of 0.54, which is an index of uniformity of particle size distribution.

  Further, the positive electrode active material produced from the precursor obtained in Comparative Example 1 contained a large amount of dense particles, but its particle size was as small as 8.2 μm and the tap density was as low as 1.8 g / cc. did it.

  Furthermore, from the results in Table 3, it was confirmed that the energy density calculated from the tap density and the initial discharge capacity was higher in Examples 1 and 2 than in Comparative Example 1.

Claims (12)

General formula Ni _x Co _y Mn _z M _t CO ₃ (where x + y + z + t = 1, 0.05 ≦ x ≦ 0.3, 0.1 ≦ y ≦ 0.4, 0.55 ≦ z ≦ 0 .8, 0 ≦ t ≦ 0.1, and M is one or more additive elements selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W). A nickel cobalt manganese carbonate composite represented,
A functional group containing hydrogen,
H / Me, which is a substance amount ratio between the hydrogen H contained and the metal component Me contained, is less than 1.60,
Including secondary particles in which a plurality of primary particles are aggregated,
The secondary particle is a positive electrode active material precursor for a non-aqueous electrolyte secondary battery having an average particle size of 15 μm or more and 45 μm or less. The secondary particles are
2. The positive electrode active material precursor for a non-aqueous electrolyte secondary battery according to claim 1, wherein [(d ₉₀ −d ₁₀ ) / average particle diameter], which is an index indicating the spread of the particle size distribution, is 0.52 or less. A positive electrode active material for a non-aqueous electrolyte secondary battery containing a lithium metal composite oxide,
The lithium metal composite oxide has a general formula of Li _{1 + α} Ni _x Co _y Mn _z M _t O ₂ (0.25 ≦ α ≦ 0.55, x + y + z + t = 1, 0.05 ≦ x ≦ 0.3, 0.1 ≦ y ≦ 0.4, 0.55 ≦ z ≦ 0.8, 0 ≦ t ≦ 0.1, M is an additive element, Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, One or more elements selected from W),
Including secondary particles in which a plurality of primary particles are aggregated,
The secondary particles have an average particle size of 12 μm or more and 40 μm or less,
A positive electrode active material for a non-aqueous electrolyte secondary battery in which the number ratio of dense secondary particles having an internal porosity of 3% or less among the secondary particles is 65% or more.   The positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 3, wherein the tap density is 2.0 g / cc or more. General formula Ni _x Co _y Mn _z M _t CO ₃ (where x + y + z + t = 1, 0.05 ≦ x ≦ 0.3, 0.1 ≦ y ≦ 0.4, 0.55 ≦ z ≦ 0 .8, 0 ≦ t ≦ 0.1, and M is one or more additive elements selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W). A method for producing a positive electrode active material precursor for a non-aqueous electrolyte secondary battery, comprising: a nickel cobalt manganese carbonate composite represented; and a functional group containing hydrogen,
In the presence of carbonate ions, an initial aqueous solution containing an ammonium ion donor, an aqueous solution containing nickel as a metal component, an aqueous solution containing cobalt as a metal component, and an aqueous solution containing manganese as a metal component were mixed. A crystallization step of generating nuclei in the mixed aqueous solution and growing the generated nuclei,
The said crystallization process is a manufacturing method of the positive electrode active material precursor for non-aqueous electrolyte secondary batteries which controls pH value of the said aqueous solution to 6.5 or more and 9.5 or less on the reaction temperature 40 degreeC reference | standard. The crystallization process includes
A nucleation step of generating nuclei in a mixed aqueous solution obtained by mixing the initial aqueous solution, an aqueous solution containing nickel as a metal component, an aqueous solution containing cobalt as a metal component, and an aqueous solution containing manganese as a metal component;
A nuclear growth step for growing the nuclei generated in the nucleation step, and
In the nucleation step, the pH value of the mixed aqueous solution is 6.5 to 9.0 based on a reaction temperature of 40 ° C., and in the nucleation growth step, the pH value of the mixed aqueous solution is 7 based on a reaction temperature of 40 ° C. The manufacturing method of the positive electrode active material precursor for nonaqueous electrolyte secondary batteries of Claim 5 controlled to 0.0-9.5. In the nucleation step, the mixed aqueous solution after the nucleation step is an aqueous solution containing nickel as a metal component, an aqueous solution containing cobalt as a metal component, and an aqueous solution containing manganese as a metal component in the presence of carbonate ions. Adding and mixing
The method for producing a positive electrode active material precursor for a non-aqueous electrolyte secondary battery according to claim 6, wherein an ammonium ion concentration in the mixed aqueous solution is 0 g / L or more and 20 g / L or less during the nucleus growth step.   The method for producing a positive electrode active material precursor for a non-aqueous electrolyte secondary battery according to claim 6 or 7, wherein in the nucleation step, the temperature of the mixed aqueous solution is maintained at 30 ° C or higher.   The non-aqueous electrolyte secondary battery according to any one of claims 6 to 8, further comprising a nuclear disintegration step in which addition of the raw material is stopped and only stirring is performed between the nucleation step and the nucleus growth step. A method for producing a positive electrode active material precursor.   The nonaqueous system according to any one of claims 5 to 9, further comprising a coating step of coating the positive electrode active material precursor for a nonaqueous electrolyte secondary battery obtained in the crystallization step with the additive element. The manufacturing method of the positive electrode active material precursor for electrolyte secondary batteries. The coating step includes
An aqueous solution containing the additive element is added to the slurry in which the positive electrode active material precursor for the non-aqueous electrolyte secondary battery is suspended, and the additive element is added to the surface of the positive electrode active material precursor for the non-aqueous electrolyte secondary battery. The step of precipitating
Spray drying a slurry in which the positive electrode active material precursor for a non-aqueous electrolyte secondary battery and the compound containing the additive element are suspended; and the positive electrode active material precursor for the non-aqueous electrolyte secondary battery; The method for producing a positive electrode active material precursor for a non-aqueous electrolyte secondary battery according to claim 10, which is any one selected from a step of mixing a compound containing an additive element with a solid phase method. A positive electrode active material precursor for a non-aqueous electrolyte secondary battery obtained by the method for producing a positive electrode active material precursor for a non-aqueous electrolyte secondary battery according to any one of claims 5 to 11, A heat treatment step for heat treatment at a temperature of ℃ or less;
A mixing step of adding a lithium compound to the particles obtained by the heat treatment step and mixing to form a lithium mixture;
A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising: a firing step of firing the lithium mixture at a temperature of 600 ° C. or higher and 1000 ° C. or lower in an oxidizing atmosphere.