JP2018014199A - Positive electrode active material for nonaqueous electrolyte secondary battery, and method for manufacturing positive electrode active material for nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive electrode active material for a nonaqueous electrolyte secondary battery, which enables the suppression of the worsening of charge and discharge characteristics owing to exposure to a high-temperature and high-humidity environment.SOLUTION: A positive electrode active material for a nonaqueous electrolyte secondary battery is provided, which comprises: particles of a lithium nickel composite oxide represented by the general formula, LiNiCoAlO(where 0.90≤x≤1.20, 0.01≤y≤0.20, and 0.01≤z≤0.10); and a region disposed on at least part of the surface of each particle of the lithium nickel composite oxide and including one or more elements selected from boron (B), phosphorus (P) and silicon (Si), lithium (Li) and oxygen (O). In the positive electrode active material, the content of carbon is 0.06 mass% or less.SELECTED DRAWING: Figure 1

Description

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

  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 output secondary battery is strongly desired as a battery for electric vehicles including hybrid vehicles.

  There is a lithium ion secondary battery as a non-aqueous electrolyte secondary battery that satisfies such requirements. A lithium ion secondary battery has a cell structure composed of a positive electrode, a negative electrode, an electrolyte, and a separator as basic elements, and an active material (positive electrode) that can desorb and insert lithium in the positive electrode and the negative electrode. Active material, negative electrode active material).

As the positive electrode active material used for the positive electrode, a composite oxide containing lithium and a transition metal is usually used. Specifically, lithium cobaltate (LiCoO ₂ ) or nickel acid as a layered material is used. Commonly used are lithium (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ) as a spinel material, lithium iron phosphate (LiFePO ₄ ) as an olivine material, and the like. Furthermore, aiming at higher energy density, lithium manganese nickel oxide (LiMn _3/2 Ni _1/2 O ₄ or the like) as a spinel material that charges and discharges at a high voltage (5 V class), and has a high capacity Development of a solid solution system (also called “excess system”) manganese-containing lithium composite oxide (for example, Li ₂ MnO ₃ —LiMO ₂ [M: Ni, Mn, Co, etc.]) as a layered material .

  Among the positive electrode active materials, lithium cobaltate is widely used mainly for portable electronic devices because a high voltage of 4V class is obtained and relatively excellent charge / discharge characteristics and cycle characteristics are obtained. However, the problem is that cobalt is expensive and the price fluctuates greatly, and lithium nickelate and lithium manganate using nickel or manganese, which are cheaper than cobalt, have attracted attention.

  However, lithium manganate is superior to lithium cobaltate in terms of thermal stability, but its charge / discharge capacity is small compared to other positive electrode active materials, and manganese elutes into the electrolyte when charge / discharge is repeated. Thus, there are drawbacks such as deterioration of cycle characteristics, and there are many practical problems as a lithium ion secondary battery.

On the other hand, lithium nickelate has a charge / discharge capacity larger than that of lithium cobaltate, but has a drawback that thermal stability and cycle characteristics are inferior to lithium cobaltate. In view of this, lithium nickel composite oxides have been developed in which a part of nickel constituting lithium nickelate is replaced with another element to improve thermal stability and cycle characteristics. Specifically, lithium nickel cobalt aluminum oxide (LiNi _X Co _y Al _Z O ₂ , x + y + z = 1) in which part of nickel is replaced with cobalt and aluminum, and lithium nickel in which part of nickel is replaced with cobalt and manganese There are cobalt manganese oxides (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ) and the like.

  By the way, when the positive electrode active material described above is used as a positive electrode of a lithium ion secondary battery, for example, when exposed to a high-temperature and high-humidity environment, it deteriorates due to reaction with moisture or carbon dioxide in the atmosphere. However, there was a problem that charge / discharge characteristics and cycle characteristics deteriorated. In addition, when the positive electrode active material is used as a positive electrode of a lithium ion secondary battery, the surface of the positive electrode active material is deteriorated due to reaction with the electrolytic solution or elution of metal ions into the electrolytic solution. There is a problem that the characteristics deteriorate.

  In order to solve the above problem, the positive electrode active material is surface-treated to suppress deterioration due to contact with moisture or carbon dioxide contained in the atmosphere, and when used as a positive electrode of a lithium ion secondary battery, Attempts have been made to suppress the surface deterioration of the positive electrode active material due to contact.

  For example, Patent Document 1 discloses a non-aqueous electrolyte secondary in which a gaseous metal halide is brought into contact with a lithium-containing composite oxide so that at least a part of the surface of the lithium-containing composite oxide is coated with the metal halide. A method for producing a positive electrode active material for a battery is disclosed.

  However, gaseous metal halides are corrosive and react with moisture in the atmosphere to generate hydrofluoric acid (HF), hydrochloric acid (HCl), etc. I couldn't say that.

  Patent Document 2 discloses that an aqueous suspension containing a composite oxide composed of lithium-transition metal element (TM), which is a core particle, is sulfated, nitrate, hydrochloride, and oxalate of element A as a raw material A. Alternatively, using an alkoxide of element A and using a fluorine-containing solution as a neutralizing agent, the addition ratio of the metal salt of element A and fluorine on the particle surface of the composite oxide composed of lithium-transition metal element (TM) 1: after precipitating a surface treatment component containing at least A element and fluorine to satisfy k (valence of A element ≦ k ≦ valence of A element × 2), a temperature of 300 to 700 ° C. in an oxygen atmosphere A method for producing a lithium composite compound particle powder that is heat-treated in a range is disclosed.

  However, when preparing an aqueous suspension containing a composite oxide composed of lithium-transition metal element (TM), which is a core particle, lithium on the surface of the composite oxide composed of lithium-transition metal element (TM) is converted into water. Elution may occur, and there is concern about a decrease in charge / discharge capacity.

  In addition, even when a positive electrode active material for a non-aqueous electrolyte secondary battery is manufactured by the manufacturing method disclosed in Patent Documents 1 and 2, the degree of suppression of deterioration in charge and discharge characteristics due to exposure to a high temperature and high humidity environment is It was not enough.

JP 2008-251480 A JP 2013-232438 A

  Therefore, in view of the problems of the above-described conventional technology, an object of one aspect of the present invention is to provide a positive electrode active material for a non-aqueous electrolyte secondary battery that can suppress a decrease in charge / discharge characteristics due to exposure to a high temperature and high humidity environment. And

In order to solve the above problems, according to one embodiment of the present invention, a general formula: Li _x Ni _1-yz Co _y Al _z O ₂ (0.90 ≦ x ≦ 1.20, 0.01 ≦ y ≦ 0) .20, 0.01 ≦ z ≦ 0.10), and disposed on at least part of the surface of the lithium nickel composite oxide particles, boron (B), phosphorus (P) and a region containing one or more elements selected from silicon (Si), lithium (Li), and oxygen (O),
Provided is a positive electrode active material for a non-aqueous electrolyte secondary battery having a carbon content of 0.06% by mass or less.

  According to one embodiment of the present invention, it is possible to provide a positive electrode active material for a non-aqueous electrolyte secondary battery that can suppress a decrease in charge / discharge characteristics due to exposure to a high temperature and high humidity environment.

Explanatory drawing of the reactor used at the contact process in embodiment of this invention. The SEM image of the particle | grains of the lithium nickel complex oxide used by the Example and the comparative example. 2 is an SEM image of lithium nickel composite oxide particles after the contact step according to Example 1. FIG. 2 is an SEM image of lithium nickel composite oxide particles after the heat treatment step according to Example 1. FIG. Explanatory drawing of the equivalent circuit used for Nyquist plot and fitting calculation.

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]
Below, the example of 1 structure of the positive electrode active material for non-aqueous electrolyte secondary batteries of this embodiment is demonstrated.

The positive electrode active material for a non-aqueous electrolyte secondary battery according to this embodiment has a general formula: Li _x Ni _1-yz Co _y Al _z O ₂ (0.90 ≦ x ≦ 1.20, 0.01 ≦ y ≦ 0.20, 0.01 ≦ z ≦ 0.10), the lithium nickel composite oxide particles, and at least part of the surface of the lithium nickel composite oxide particles, boron (B), A region containing one or more elements selected from phosphorus (P) and silicon (Si), lithium (Li), and oxygen (O) can be included. And the positive electrode active material for nonaqueous electrolyte secondary batteries of this embodiment can make carbon content 0.06 mass% or less.

The positive electrode active material for a non-aqueous electrolyte secondary battery of the present embodiment (hereinafter, also simply referred to as “positive electrode active material”) has the general formula: Li _x Ni _1-yz Co _y Al _z O _{2 as described above.} Lithium nickel composite oxide particles represented by (0.90 ≦ x ≦ 1.20, 0.01 ≦ y ≦ 0.20, 0.01 ≦ z ≦ 0.10) can be included.

  In the above general formula, the range of the atomic ratio x indicating the lithium (Li) content is preferably 0.90 ≦ x ≦ 1.20, more preferably 0.95 ≦ x ≦ 1.15. preferable. This is because when the atomic ratio x is less than 0.90, the charge / discharge capacity of the secondary battery may decrease, and when the atomic ratio x exceeds 1.20, the thermal stability of the secondary battery may decrease. Because there is.

  In the above general formula, the range of the atomic ratio y indicating the cobalt (Co) content is preferably 0.01 ≦ y ≦ 0.20, and 0.03 ≦ y ≦ 0.15. Is more preferable. This is because when the atomic ratio y is less than 0.01, the cycle characteristics of the secondary battery may not be sufficient, and when the atomic ratio y exceeds 0.20, the charge / discharge capacity of the secondary battery is reduced due to the decrease in nickel content. This is because there is a case where the value decreases.

  Furthermore, in the above general formula, the range of the atomic ratio z indicating the aluminum (Al) content is preferably 0.01 ≦ z ≦ 0.10, and 0.01 ≦ z ≦ 0.05. Is more preferable. This is because when the atomic ratio z is less than 0.01, the thermal stability of the secondary battery may be lowered, and when the atomic ratio z exceeds 0.10, the positive electrode active material is not dissolved and a different phase is generated. This is because the charge / discharge capacity of the secondary battery may decrease.

  And in said general formula, it is preferable that atomic ratio 1-yz which shows content of nickel (Ni) is in the range of 0.70 or more and 0.98 or less, and is 0.80 or more and 0.96 or less. It is more preferable to be within the range. This is because when 1-yz is less than 0.70, the charge / discharge capacity of the secondary battery may decrease, and when 1-yz exceeds 0.98, the thermal stability of the secondary battery is reduced. This is because it may not be enough.

  The carbon content of the positive electrode active material of the present embodiment can be 0.06% by mass or less. Charge / discharge after the weather resistance test by setting the carbon content of the positive electrode active material to 0.06% by mass or less, that is, after being exposed to a high temperature and high humidity environment, for example, a temperature of 80 ° C. or higher and a humidity of 60% or higher The capacity can be kept high.

  Although the carbon content of the positive electrode active material of this embodiment is 0.06% by mass or less, the reason why the charge / discharge capacity can be kept high even when exposed to a high temperature and high humidity environment is not clear, The inventor of the present invention presumes as follows.

  As described above, the positive electrode active material of the present embodiment is one or more selected from boron, phosphorus, and silicon disposed on at least part of the surface of the lithium nickel composite oxide particles and the lithium nickel composite oxide particles. And a region containing lithium and oxygen (hereinafter also referred to as “boron-containing region”). And by making the carbon content of the positive electrode active material of this embodiment 0.06 mass% or less, the amount of carbon contained in the boron-containing region, more specifically, the content of organic matter is also reduced. It is considered that the boron-containing region can be densified. For this reason, even if the positive electrode active material of this embodiment is exposed to a high-temperature and high-humidity environment, the lithium nickel composite oxide particles hardly undergo surface deterioration, a high charge / discharge capacity can be obtained, and the positive electrode resistance can also be reduced. it is conceivable that.

  The carbon content of the positive electrode active material of this embodiment is more preferably 0.05% by mass or less. In addition, since the one where the carbon content of the positive electrode active material of this embodiment is low is preferable, the lower limit is not specifically limited, For example, it can be set to 0 or more. However, the carbon content can be reduced, for example, by performing a heat treatment described later. However, if the heat treatment is performed for a long time for the purpose of reducing the carbon content, the composition of the lithium nickel composite oxide may deviate from the target composition. The carbon content is preferably not excessively reduced. For this reason, it is preferable that carbon content shall be 0.02 mass% or more, for example.

  The lithium nickel composite oxide particles contained in the positive electrode active material of the present embodiment can be composed of secondary particles in which primary particles are aggregated. The secondary particles of the lithium nickel composite oxide particles preferably have an average particle diameter in the range of 3 μm to 20 μm, and more preferably in the range of 5 μm to 15 μm.

  This is because when the average particle diameter of the secondary particles of the lithium nickel composite oxide particles is less than 3 μm, the packing density of the lithium nickel composite oxide particles decreases when the positive electrode is formed, and the charge / discharge capacity of the secondary battery is reduced. It is because it falls. On the other hand, when the average particle diameter of the secondary particles of the lithium nickel composite oxide particles exceeds 20 μm, the contact area between the positive electrode active material and the electrolyte in the secondary battery is reduced, so that the charge / discharge capacity of the secondary battery is reduced. It is because it may end up.

  Here, the average particle diameter means the volume integrated average value in the particle size distribution obtained by the laser diffraction / scattering method, and the average particle diameter has the same meaning in this specification.

  The positive electrode active material of this embodiment is disposed on at least part of the surface of the lithium nickel composite oxide particles, and one or more elements selected from boron (B), phosphorus (P), and silicon (Si), A region containing lithium (Li) and oxygen (O) (a region containing boron or the like) can be included. As described above, the particles of the lithium nickel composite oxide can be composed of secondary particles in which the primary particles are aggregated, and the boron-containing region is, for example, the primary that constitutes the particles of the lithium nickel composite oxide. It can be placed on the surface of the particles and secondary particles.

  The boron-containing region is present as a region containing one or more elements selected from boron, phosphorus, and silicon, lithium, and oxygen in at least part of the surface of the lithium nickel composite oxide particles. There is no need for a clear interface between the lithium nickel composite oxide particles and the boron-containing region.

  For example, the boron-containing region can be formed and arranged as a region covering a part of the surface of the lithium nickel composite oxide particles. Further, the boron-containing region may be formed and arranged as a film covering the entire surface of the lithium nickel composite oxide particles. In the case where the boron-containing region is formed and arranged as a region covering a part of the surface of the lithium nickel composite oxide particles, or formed and arranged as a film covering the entire surface, in any case There is no need for a clear interface between the lithium nickel composite oxide particles and the boron-containing region.

  However, one or more elements selected from boron (B), phosphorus (P), and silicon (Si) are completely dissolved in the inside of the lithium nickel composite oxide particles, and the inside of the lithium nickel composite oxide particles When there is no difference in composition between the particle surfaces, the effect of obtaining high charge / discharge characteristics cannot be obtained, and the charge / discharge characteristics may be significantly reduced. For this reason, it is preferable that one or more elements selected from boron (B), phosphorus (P), and silicon (Si) are present unevenly on the particle surface of the lithium nickel composite oxide. For example, it can also be configured such that the boron-containing region exists only on the surface of the lithium nickel composite oxide particles.

  The existence form of the elements constituting the boron-containing region is not particularly limited. For example, in a boron-containing region, a lithium component (lithium hydroxide, lithium carbonate, etc.) present on the surface of lithium nickel composite oxide particles reacts with one or more elements selected from boron, phosphorus, and silicon. , Li—O—B bond, Li—O—P bond, Li—O—Si bond, and the like.

  As described above, the positive electrode active material of the present embodiment is disposed on at least a part of the surface of the lithium nickel composite oxide particles, and one or more elements selected from boron, phosphorus, and silicon, and lithium And a region containing oxygen, that is, a region containing boron or the like. Therefore, the positive electrode active material of this embodiment can contain one or more elements selected from boron, phosphorus, and silicon. At this time, the content of one or more elements selected from boron, phosphorus, and silicon is not particularly limited. For example, depending on the environment in which the positive electrode active material of the present embodiment is used, the environment to be stored, and the like. Can be arbitrarily selected.

  For example, when the positive electrode active material of this embodiment contains boron, the content of boron (B) in the positive electrode active material of this embodiment is preferably 0.01% by mass or more and 0.10% by mass or less. This is because, for example, when the positive electrode active material of the present embodiment is applied to the positive electrode active material layer forming paste of a non-aqueous electrolyte secondary battery and the boron content is in the above range, the battery characteristics are not impaired. This is because it is possible to improve the stability (inhibition of gelation) of the positive electrode active material layer forming paste, which is preferable.

  Moreover, when the positive electrode active material of this embodiment contains phosphorus, it is preferable that content of phosphorus (P) of the positive electrode active material of this embodiment is 0.01 mass% or more and 0.10 mass% or less. This is because, for example, when the positive electrode active material of this embodiment is applied to the positive electrode active material layer forming paste of a non-aqueous electrolyte secondary battery and the phosphorus content is in the above range, the battery characteristics are not impaired. This is because it is possible to improve the stability (inhibition of gelation) of the positive electrode active material layer forming paste, which is preferable.

  Moreover, when the positive electrode active material of this embodiment contains silicon, it is preferable that content of the silicon (Si) of the positive electrode active material of this embodiment is 0.05 mass% or more and 0.30 mass% or less. . This is because, for example, when the positive electrode active material of the present embodiment is applied to the positive electrode active material layer forming paste of a non-aqueous electrolyte secondary battery, and the silicon content is in the above range, the battery characteristics are not impaired. This is because it is possible to improve the stability (inhibition of gelation) of the positive electrode active material layer forming paste, which is preferable.

  The positive electrode active material for a non-aqueous electrolyte secondary battery of the present embodiment described above is disposed on at least a part of the surface of the lithium nickel composite oxide particles, and boron (B), phosphorus (P), and silicon ( A region containing one or more elements selected from Si), lithium (Li), and oxygen (O) can be included. Moreover, carbon content can be 0.06 mass% or less.

  For this reason, the positive electrode active material for a non-aqueous electrolyte secondary battery according to this embodiment may be a positive electrode active material for a non-aqueous electrolyte secondary battery that can suppress a decrease in charge / discharge characteristics due to exposure to a high temperature and high humidity environment. it can. That is, even when a secondary battery using the positive electrode active material as a positive electrode material is formed after the positive electrode active material for a non-aqueous electrolyte secondary battery of the present embodiment is exposed to a high temperature and high humidity environment, high charge / discharge characteristics Can be demonstrated.

Furthermore, the positive electrode active material for a nonaqueous electrolyte secondary battery of the present embodiment can be suitably used as a positive electrode for a secondary battery.
[Method for producing positive electrode active material for non-aqueous electrolyte secondary battery]
Next, a configuration example of the method for producing the positive electrode active material for a non-aqueous electrolyte secondary battery according to the present embodiment will be described.

  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”) can have the following steps.

General formula: Li _x Ni _1-yz Co _y Al _z O ₂ (0.90 ≦ x ≦ 1.20, 0.01 ≦ y ≦ 0.20, 0.01 ≦ z ≦ 0.10) A contacting step in which particles of the lithium nickel composite oxide are brought into contact with a gas containing one or more compounds selected from a boron compound, a phosphorus compound, and a silicon compound.
The heating process which heat-processes the obtained substance at the temperature of 600 to 800 degreeC after a contact process.

  In addition, the positive electrode active material for non-aqueous electrolyte secondary batteries described above can be manufactured by the method for manufacturing a positive electrode active material for non-aqueous electrolyte secondary batteries of the present embodiment. For this reason, a part of the description already described will be omitted.

Hereinafter, each step will be specifically described.
(A) Contacting step In the contacting step, particles of lithium nickel composite oxide can be brought into contact with a gas containing vapor of one or more compounds selected from a boron compound, a phosphorus compound, and a silicon compound. By carrying out the contact step, a boron-containing region can be formed on the particle surface of the lithium nickel composite oxide.

  When using a boron compound in the contacting step, the boron compound is not particularly limited, but is preferably a volatile boron compound, more preferably a boron compound having a boiling point of 300 ° C. or less, More preferred is an alkylboric acid having a boiling point of 250 ° C. or lower.

  In addition, the said boiling point means the boiling point under atmospheric pressure (101.325 kPa), and unless otherwise indicated in this specification, a boiling point means the boiling point under atmospheric pressure hereafter.

Examples of the boron compound used in the contacting step include trimethyl borate (trimethoxyborane) [B (OCH ₃ ) ₃ ] having a boiling point of 68 ° C., and triethyl borate (triethoxyborane) [B] having a boiling point of 120 ° C. One or more selected from (OC ₂ H ₅ ) ₃ ] can be particularly preferably used.

  When using a phosphorus compound in the contacting step, the compound is not particularly limited, but is preferably a volatile phosphorus compound, more preferably a phosphorus compound having a boiling point of 300 ° C. or lower, Is more preferably an alkyl phosphoric acid at 250 ° C. or lower.

Examples of the phosphorus compound used in the contacting step include trimethyl phosphite (trimethoxyphosphine) [P (OCH ₃ ) ₃ ] having a boiling point of 111 ° C. and triethyl phosphite (triethoxy phosphite) having a boiling point of 156 ° C. Fin) [P (OC ₂ O ₅ ) ₃ ], trimethyl phosphate (trimethoxyphosphine oxide) [P (O) (OCH ₃ ) ₃ ] having a boiling point of 197 ° C., triethyl phosphate having a boiling point of 215 ° C. (Triethoxyphosphine oxide) [P (O) (OC ₂ H ₅ ) ₃ ], and dimethyl phosphate (dimethyl phosphate) having a boiling point of 174 ° C. [P (O) (OH) (OCH ₃ ) ₂ ] One or more selected from the above can be particularly preferably used.

  When using a silicon compound in the contacting step, the silicon compound is not particularly limited, but is preferably a volatile silicon compound, more preferably a silicon compound having a boiling point of 300 ° C. or less, More preferred is an alkylsilicic acid having a boiling point of 250 ° C. or lower.

Examples of the silicon compound used in the contacting step include dimethoxydimethylsilane [Si (CH ₃ ) ₂ (OCH ₃ ) ₂ ] having a boiling point of 81 ° C., and trimethoxysilane [Si (H) (OCH) having a boiling point of 83 ° C. ₃ ) ₃ ], trimethoxymethylsilane [Si (CH ₃ ) (OCH ₃ ) ₃ ] having a boiling point of 103 ° C., tetramethyl orthosilicate (tetramethoxysilane) [Si (OCH ₃ ) ₄ having a boiling point of 122 ° C. ], Vinyltrimethoxysilane [Si (C ₂ H ₃ ) (OCH ₃ ) ₃ ] having a boiling point of 123 ° C., triethoxymethylsilane [Si (CH ₃ ) (OC ₂ H ₅ ) ₃ having a boiling point of 143 ° C. ], a boiling point of 165 ° C. tetraethyl orthosilicate _{(tetraethoxysilane) [Si (OC 2 H 5} ) 4], the boiling point at 2kPa Is 2 ° C. 3- aminopropyltrimethoxysilane _{[Si (C 3 H 6 NH} 2) (OCH 3) 3] can be particularly preferably used one or more kinds selected from.

  In the contacting step, for example, as shown in FIG. 1, one or more types selected from a first storage container 3 storing lithium nickel composite oxide particles, a boron compound, a phosphorus compound, and a silicon compound in a reaction container 1. A second storage container 5 for storing the compound is installed. Then, lithium nickel composite oxide particles 2, one or more compounds 4 selected from boron compounds, phosphorus compounds, and silicon compounds are placed in the respective storage containers and left as they are in the atmospheric gas, or the fans 6. Can be carried out by rotating.

  In addition, when using several types of compounds as 1 or more types of compounds selected from a boron compound, a phosphorus compound, and a silicon compound, according to the number of the kind of this compound, several 2nd storage containers 5 are used. It can also be installed. In addition, a plurality of types of compounds can be mixed and installed in the second storage container 5.

  The reaction vessel 1 is preferably a highly airtight vessel so that the vapor of one or more compounds selected from atmospheric gas, boron compound, phosphorus compound, and silicon compound does not leak outside. The material of the reaction vessel 1 is not particularly limited as long as it does not react with the vapor of one or more compounds selected from boron compounds, phosphorus compounds, and silicon compounds. Examples of the material of the reaction vessel 1 include plastics such as polyethylene, polypropylene, and Teflon (registered trademark); ceramics such as alumina, quartz, and glass; metals such as stainless steel (SUS304, SUS316, and the like), titanium, and the like.

  The first storage container 3 and the second storage container 5 do not react with one or more compounds 4 selected from lithium nickel composite oxide particles 2, boron compounds, phosphorus compounds, and silicon compounds, respectively, and have durability. It has only to have it and is not particularly limited. For example, it can be arbitrarily selected according to the kind of one or more compounds 4 selected from the lithium nickel composite oxide particles 2 to be used, a boron compound, a phosphorus compound, and a silicon compound.

  Examples of the material of the first storage container 3 and the second storage container 5 include plastics such as polyethylene, polypropylene, and Teflon; ceramics such as alumina, quartz, and glass; metals such as stainless steel and titanium.

  The atmosphere gas in the reaction vessel 1 is not particularly limited, and is arbitrarily selected according to the type of the lithium nickel composite oxide particles 2 to be used, one or more kinds of compounds 4 selected from boron compounds, phosphorus compounds, and silicon compounds. You can choose. However, the atmosphere gas in the reaction vessel 1 is preferably a gas that does not react with the lithium nickel composite oxide particles 2 or one or more compounds 4 selected from boron compounds, phosphorus compounds, and silicon compounds. Examples of the atmospheric gas in the reaction vessel 1 include air, nitrogen, argon, and the like.

Carbon dioxide (CO ₂ ) or moisture (H ₂ O) reacts with the lithium nickel composite oxide particles 2 and one or more compounds 4 selected from boron compounds, phosphorus compounds, and silicon compounds. Easy to do. For this reason, it is preferable to use carbon dioxide gas or atmospheric gas with a low water content.

  Thus, the atmospheric gas in the reaction vessel 1 is preferably a gas selected from, for example, dry air, decarboxylated gas-treated dry air, high-purity nitrogen, and high-purity argon.

  The dry air preferably has a dew point temperature of −30 ° C. or lower, and more preferably −50 ° C. or lower.

  High purity nitrogen has a nitrogen content of 99.9995 vol. %, Preferably 99.998 vol. More preferably, it is higher than%. High-purity argon has, for example, an argon content of 99.999 vol. %, Preferably 99.9995 vol. More preferably, it is higher than%.

  Depending on the kind of one or more compounds 4 selected from a boron compound, a phosphorus compound, and a silicon compound, when air or the like is used as the atmospheric gas, the atmospheric gas is selected from a boron compound, a phosphorus compound, and a silicon compound. Depending on the mixing ratio of one or more compounds with the vapor, there is a risk of explosion or oxidative degradation due to oxygen. For this reason, in such a case, it is preferable to use nitrogen or argon as the atmospheric gas instead of air.

  As described above, the atmospheric gas in the reaction vessel 1 is not particularly limited, and can be selected according to the type of one or more compounds 4 selected from the boron compound, phosphorus compound, and silicon compound to be used.

  Then, as described above, the respective raw materials are set in the first storage container 3 and the second storage container 5 in the reaction container 1, and the reaction container 1 is replaced with a predetermined atmospheric gas, and then left as it is, or the fan 6 is installed. By rotating, the atmosphere in the reaction vessel 1 can be made uniform to perform the contact step.

  When the reaction vessel 1 is left as it is or when the fan 6 is rotated, the vapor of one or more compounds 4 selected from the boron compound, the phosphorus compound, and the silicon compound diffuses from the second storage vessel 5 into the atmospheric gas. To do. And the vapor | steam of the 1 or more types of compound 4 selected from the boron compound, phosphorus compound, and silicon compound which diffused in atmospheric gas is on the surface of the particle | grains 2 of the lithium nickel complex oxide particle 2 in the 1st storage container 3. In contact and consumed. Therefore, as the reaction time elapses, one or more compounds 4 selected from boron compounds, phosphorus compounds, and silicon compounds initially stored in the first storage container 3 and in the second storage container 5 are transferred. To do.

  The method for controlling the amount of one or more elements selected from boron, phosphorus and silicon contained in at least part of the surface of the lithium nickel composite oxide particles and the thickness of the boron-containing region is not particularly limited. For example, it can be controlled by the following method.

  One control method includes a method of controlling by the amount of raw material stored in each storage container of the reaction container 1. First, in the first storage container 3 and the second storage container 5 in the reaction container 1, one or more kinds selected from a predetermined amount of lithium nickel composite oxide particles 2, a boron compound, a phosphorus compound, and a silicon compound, respectively. Compound 4 is added. However, at this time, the amount of the lithium nickel composite oxide particles 2 to be put in each storage container and one or more compounds 4 selected from a boron compound, a phosphorus compound, and a silicon compound is produced. These particles are adjusted so as to have an amount corresponding to the amount of one or more elements selected from boron, phosphorus, and silicon, the thickness of the boron-containing region, and the like. Then, the inside of the reaction vessel 1 is replaced with atmospheric gas and left as it is, or the fan 6 is rotated to complete one or more compounds 4 selected from the boron compound, phosphorus compound, and silicon compound in the second storage vessel 5. It can be controlled by terminating the reaction when it disappears.

  As another control method, a method of controlling by the reaction time in the reaction vessel 1 can be mentioned. Even in this case, first, the first storage container 3 and the second storage container 5 in the reaction container 1 are each selected from a predetermined amount of lithium nickel composite oxide particles 2, a boron compound, a phosphorus compound, and a silicon compound. One or more compounds 4 are added. However, in this case, the amount of one or more compounds 4 selected from the boron compound, the phosphorus compound, and the silicon compound to be put into the second storage container 5 is boron, phosphorus, And an amount of one or more elements selected from silicon, or an amount corresponding to the thickness of the boron-containing region, etc. Then, after the inside of the reaction vessel 1 is replaced with the atmospheric gas, it is left as it is or when the fan 6 is rotated and when a predetermined time has elapsed, one or more compounds 4 selected from a boron compound, a phosphorus compound, and a silicon compound are produced. It is also possible to control by removing the second storage container 5 from the reaction container 1 with the remaining portion, and terminating the reaction.

In addition, although the contact process was demonstrated by the example using the reaction apparatus shown in FIG. 1 so far, the reaction apparatus used in a contact process is not limited to the example shown in FIG. Various reaction apparatuses can be used as long as they are capable of bringing lithium nickel composite oxide particles into contact with vapors of one or more compounds selected from a boron compound, a phosphorus compound, and a silicon compound.
(B) Heating step In the heating step, particles of the lithium nickel composite oxide brought into contact with the substance obtained in the contact step, that is, one or more compounds selected from a boron compound, a phosphorus compound, and a silicon compound are added to an atmosphere furnace. It can be heated inside.

  By carrying out the heating step, an organic component contained in one or more compounds selected from boron compounds, phosphorus compounds, and silicon compounds brought into contact with the surfaces of the lithium nickel composite oxide particles in the contact step, Traces of moisture can be removed. In addition, a region containing one or more elements selected from boron, phosphorus, and silicon, lithium, and oxygen, which are disposed on at least part of the surface of the lithium nickel composite oxide particles (a boron-containing region) ) Can be improved in crystallinity and denseness.

  The furnace used when performing the heating step, for example, an electric furnace is not particularly limited, but is preferably a furnace capable of controlling the atmosphere during the heat treatment, for example. For example, an atmosphere furnace, a tubular furnace, a pusher furnace, a roller hearth furnace, etc. are mentioned.

  The heating temperature in the heating step is preferably 600 ° C. or higher and 800 ° C. or lower, and more preferably 650 ° C. or higher and 750 ° C. or lower.

  If the heating temperature is less than 600 ° C., organic components and trace moisture contained in one or more compounds selected from boron compounds, phosphorus compounds, and silicon compounds may not be sufficiently reduced or removed. Because. In addition, when the heating temperature is higher than 800 ° C., the sintering of the lithium nickel composite oxide particles proceeds and the specific surface area decreases, and the contact area with the electrolytic solution decreases when used as a secondary battery. This is because the capacity may decrease.

There is no particular limitation on the atmosphere used in the heating step. For example, it is preferable to use a gas that does not react with a vacuum atmosphere or one or more compounds selected from the group consisting of a boron compound, a phosphorus compound, and a silicon compound disposed on the surface of lithium nickel composite oxide or lithium nickel oxide particles to be used. Can do. The atmospheric gas used in the heating step is more preferably an oxygen concentration of 60% by volume or more and a carbon dioxide (CO ₂ ) partial pressure of 10 Pa or less. This is because when the oxygen concentration is less than 60%, nickel (Ni) in the lithium nickel composite oxide is reduced, and the charge / discharge capacity may be reduced when a secondary battery is formed. This is because if the pressure is higher than 10 Pa, the charge / discharge capacity may be reduced when the secondary battery is reacted with lithium in the lithium nickel composite oxide.

  The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries of this embodiment can have arbitrary processes other than the above-mentioned contact process and a heating process.

  For example, it can have a lithium nickel composite oxide manufacturing process which manufactures the particles of lithium nickel composite oxide to be subjected to the contact process. The specific process (step) of a lithium nickel composite oxide manufacturing process is not specifically limited, What is necessary is just the process which can manufacture the particle | grains of lithium nickel composite oxide. The lithium nickel composite oxide manufacturing process can include, for example, the following steps.

While stirring and putting water in the reaction tank, a mixed aqueous solution of nickel sulfate, cobalt sulfate and aluminum sulfate, aqueous sodium hydroxide and aqueous ammonia were added simultaneously while controlling the pH value in the tank to 11 or more and 13 or less. Crystallization step to obtain nickel composite hydroxide particles.
A roasting step in which the nickel composite hydroxide particles are roasted at a temperature of 500 ° C. or higher and 700 or lower to obtain a nickel composite oxide.
A firing step of mixing a nickel composite oxide and lithium hydroxide monohydrate and firing the mixture at a temperature of 650 ° C. or higher and 850 or lower to obtain a lithium nickel composite oxide.
A crushing step for crushing the lithium nickel composite oxide.

  In addition, although arbitrary processes were demonstrated to the example for the lithium nickel complex oxide manufacturing process here, it is not limited to the example of the said process, The manufacturing method of the positive electrode active material of this embodiment is various arbitrary as needed. It can have the process of.

  The positive electrode active material for a non-aqueous electrolyte secondary battery obtained by the method for manufacturing a positive electrode active material for a non-aqueous electrolyte secondary battery according to the present embodiment described above is formed on at least a part of the surface of the lithium nickel composite oxide particles. The region may be disposed and contain one or more elements selected from boron (B), phosphorus (P), and silicon (Si), lithium (Li), and oxygen (O). Moreover, carbon content can be 0.06 mass% or less.

  For this reason, the positive electrode active material for a nonaqueous electrolyte secondary battery obtained by the method for manufacturing a positive electrode active material for a nonaqueous electrolyte secondary battery according to the present embodiment exhibits a decrease in charge / discharge characteristics due to exposure to a high temperature and high humidity environment. It can be set as the positive electrode active material for non-aqueous electrolyte secondary batteries which can be suppressed. That is, after exposing the positive electrode active material for a non-aqueous electrolyte secondary battery to a high-temperature and high-humidity environment, high charge / discharge characteristics are exhibited even when a secondary battery using the positive electrode active material as a positive electrode material is formed. be able to.

  Furthermore, the positive electrode active material for a nonaqueous electrolyte secondary battery obtained by the method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to this embodiment can be suitably used as a positive electrode for a secondary battery.

  In addition, the method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to the present embodiment is characterized in that an atmosphere gas containing at least one compound selected from a boron compound, a phosphorus compound, and a silicon compound is used as lithium nickel composite oxide particles. A simple manufacturing method in which the surface is brought into contact with and heated. For this reason, the positive electrode active material for nonaqueous electrolyte secondary batteries provided with low-cost, high-temperature, high-humidity resistance can be produced, which is industrially useful.

  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]
A positive electrode active material for a non-aqueous electrolyte secondary battery was manufactured and evaluated by the following procedure.
(1) Method for producing positive electrode active material for non-aqueous electrolyte secondary battery (lithium nickel composite oxide production process)
First, the temperature in the tank is set to 50 ° C. while stirring by putting water in the reaction tank, and a mixed aqueous solution of nickel sulfate, cobalt sulfate, and aluminum sulfate (Ni: Co: Al = in terms of metal element molar ratio). 82: 15: 3), 25% by mass aqueous sodium hydroxide solution and 25% by mass ammonia water were added simultaneously, and the crystallization was carried out for 11 hours while controlling the pH value in the reaction vessel to 11.5 based on the liquid temperature of 25 ° C. To produce nickel composite hydroxide particles (crystallization step).

  After completion of the crystallization step, the product was roasted at 600 ° C. in an air atmosphere to obtain nickel composite oxide particles (roasting step).

  The nickel composite oxide particles obtained in the roasting step and lithium hydroxide monohydrate are mixed, and the resulting mixture is calcined at 500 ° C. for 3 hours in an oxygen atmosphere, and then at 750 ° C. for 20 hours. Firing (firing step). When preparing the mixture, the nickel composite oxide particles and the lithium hydroxide monohydrate were weighed and mixed so that the metal element molar ratio was Li / (Ni + Co + Al) = 1.02.

The product obtained in the firing step was crushed to obtain lithium nickel composite oxide particles (Li _1.02 Ni _0.82 Co _0.15 Al _0.03 O ₂ ) (crushing step).

  The obtained lithium nickel composite oxide particles were observed for particle shape with a scanning electron microscope (SEM) (manufactured by JEOL Ltd., model number: JSM-7100F). The photograph taken is shown in FIG. It was confirmed that the obtained lithium nickel composite oxide particles consisted of secondary particles formed by aggregation of primary particles.

  The average particle diameter of the obtained lithium nickel composite oxide particles (secondary particles) was evaluated by a laser diffraction scattering method to be 12.0 μm.

The same lithium nickel composite oxide particles are used in the following other examples and comparative examples.
(Contact process)
The contact process was performed using the reaction apparatus shown in FIG.

In the first storage container 3, 204.0 g of lithium nickel composite oxide particles obtained in the lithium nickel composite oxide production process were placed as lithium nickel composite oxide particles 2. In addition, 2.4 g of trimethyl borate (trimethoxyborane) [B (OCH ₃ ) ₃ ] as one or more compounds 4 selected from a boron compound, a phosphorus compound, and a silicon compound was placed in the second storage container 5. . And each storage container which accommodated the raw material was installed in the reaction container 1, and the reaction container 1 was sealed.

  The reaction container 1, the first storage container 3, and the second storage container 5 were all made of stainless steel.

  The content of nitrogen, which is an atmospheric gas, in the reaction vessel 1 is 99.9995 vol. After replacement and filling with nitrogen gas higher than% (dew point temperature: −50 ° C. or lower), the fan 6 was rotated and the atmosphere gas was circulated in the reaction vessel 1, and left at room temperature (25 ° C.). Thereby, the atmosphere gas containing the vapor | steam of trimethyl borate was made to contact the surface of the particle | grains 2 of lithium nickel complex oxide.

  When the particles of the lithium nickel composite oxide after the above contact step were analyzed by ICP emission spectrometry, it was confirmed that 0.05% by mass of boron (B) as a trimethyl borate component was contained. .

Further, when the surface shape of the lithium nickel composite oxide was observed with a scanning electron microscope (SEM), as shown in FIG. 3, the region containing boron, lithium, and oxygen was particles of the lithium nickel composite oxide. It was confirmed that the surface was uniformly formed. That is, it was confirmed that a region containing boron, lithium, and oxygen was formed as a coating covering the lithium nickel composite oxide particles on the surface of the lithium nickel composite oxide particles.
(Heating process)
Next, the lithium nickel composite oxide subjected to the above contact step is heated in an oxygen stream at 700 ° C. for 1 hour and then cooled to room temperature to obtain a positive electrode active material for a non-aqueous electrolyte secondary battery according to Example 1. It was. As the oxygen gas, one having an oxygen content of about 100% by volume and a carbon dioxide partial pressure of 10 Pa or less is used, and the same applies to Example 2 and Comparative Example 4 below.

  When the surface shape of the obtained positive electrode active material for a non-aqueous electrolyte secondary battery was observed with a scanning electron microscope (SEM), there was no sintering of primary particles as shown in FIG. It was confirmed that Therefore, as in the case before the heating step, a region containing boron, lithium, and oxygen is formed on the surface of the lithium nickel composite oxide particles as a film covering the lithium nickel composite oxide particles. It was confirmed.

  The amount of carbon contained in the obtained positive electrode active material for a non-aqueous electrolyte secondary battery was measured by a high-frequency combustion infrared absorption method using a carbon analyzer (manufactured by LECO, model number: CS-600) to be 0.03 mass. %Met.

Moreover, when the positive electrode active material for non-aqueous electrolyte secondary batteries was also analyzed by ICP emission analysis, it was confirmed that the boron content was 0.05% by mass. Moreover, it has confirmed that content of silicon was less than a detection limit, ie, less than 0.02 mass%.
(2) Evaluation Results Coin cells (positive electrode / separator and electrolyte / negative electrode) using the positive electrode active material for a non-aqueous electrolyte secondary battery produced by the above procedure as a positive electrode were prepared, and charge / discharge characteristics were evaluated. When the C rate was set to 0.05 C and the battery was charged to a cut-off voltage of 4.3 V and then discharged to a cut-off voltage of 3.0 V, the charge capacity was 217 mAh / g, and the discharge capacity was 199 mAh / g. I was able to confirm.
Moreover, positive electrode resistance was measured using the produced coin cell. After charging the coin cell at a charging potential of 4.1 V and using a frequency response analyzer and a potentiogalvanostat (manufactured by Solartron, 1255B), a Nyquist plot as shown in FIG. Fitting calculation was performed using the equivalent circuit shown in FIG. 5B, and the value of the positive electrode resistance was calculated to be 2.4Ω.

  Next, the positive electrode active material for a non-aqueous electrolyte secondary battery was put in a Teflon container and left in a constant temperature and humidity chamber set at a temperature of 80 ° C. and a humidity of 60% for a weather resistance test. Then, a coin cell (positive electrode / separator and electrolyte / negative electrode) using the positive electrode active material for a non-aqueous electrolyte secondary battery after the weather resistance test as a positive electrode was prepared, and the charge / discharge characteristics were evaluated in the same manner as described above. It was confirmed that the charge capacity was 210 mAh / g and the discharge capacity was 194 mAh / g.

  Moreover, when the value of positive electrode resistance was computed like the above using the produced coin cell, it was confirmed that it was 3.2Ω.

Production conditions and evaluation results are summarized in Tables 1 and 2.
[Example 2]
A positive electrode active material for a non-aqueous electrolyte secondary battery was produced and evaluated in the same manner as in Example 1 except that the conditions for the contact step and the heating step were changed as follows.
(1) About the manufacturing method of the positive electrode active material for non-aqueous electrolyte secondary batteries (contact process)
The amount of the lithium nickel composite oxide particles 2 in the first storage container 3 is set to 201.7 g, and the orthoke as one or more compounds 4 selected from a boron compound, a phosphorus compound, and a silicon compound to be stored in the second storage container 5. The contact step was carried out in the same manner as in Example 1 except that 4.0 g of acid tetraethyl (tetraethoxysilane) [Si (OC ₂ H ₅ ) ₄ ] was used.

  When the lithium nickel composite oxide subjected to the above contact step was analyzed by ICP emission analysis, it was confirmed that 0.07% by mass of silicon (Si), which is a tetraethyl orthosilicate component, was contained.

Moreover, when the surface shape of the lithium nickel composite oxide was observed with a scanning electron microscope (SEM), a region containing silicon, lithium, and oxygen was uniformly formed on the surface of the lithium nickel composite oxide particles. It has been confirmed. That is, it was confirmed that a region containing silicon, lithium, and oxygen was formed as a coating covering the lithium nickel composite oxide particles on the surface of the lithium nickel composite oxide particles.
(Heating process)
Next, the lithium nickel composite oxide subjected to the above contact step was heated in an oxygen stream at 700 ° C. for 1 hour, and then cooled to room temperature to obtain a positive electrode active material for a non-aqueous electrolyte secondary battery.

  The amount of carbon contained in the obtained positive electrode active material for a non-aqueous electrolyte secondary battery was measured by a high-frequency combustion infrared absorption method using a carbon analyzer (manufactured by LECO, model number: CS-600) to be 0.05 mass. %Met.

  When the obtained positive electrode active material for a non-aqueous electrolyte secondary battery was also analyzed by ICP emission analysis, it was confirmed that the boron content was less than the detection limit, that is, less than 0.01% by mass. Moreover, it has confirmed that content of silicon was 0.07 mass%.

When the surface shape of the obtained positive electrode active material for a non-aqueous electrolyte secondary battery was observed with a scanning electron microscope (SEM), the region containing silicon, lithium, and oxygen was a particle of lithium nickel composite oxide. It was confirmed that the surface was uniformly formed. That is, it was confirmed that a region containing silicon, lithium, and oxygen was formed as a coating covering the lithium nickel composite oxide particles on the surface of the lithium nickel composite oxide particles.
(2) Evaluation Results Coin cells (positive electrode / separator and electrolyte / negative electrode) using the obtained positive electrode active material for a nonaqueous electrolyte secondary battery as a positive electrode were prepared, and charge / discharge characteristics were evaluated. When the C rate was set to 0.05 C and the battery was charged to a cutoff voltage of 4.3 V and then discharged to a cutoff voltage of 3.0 V, the charge capacity was 218 mAh / g, and the discharge capacity was 195 mAh / g. I was able to confirm.

  Moreover, when the value of positive electrode resistance was computed like the above using the produced coin cell, it was confirmed that it was 2.5Ω.

  Next, the positive electrode active material for a non-aqueous electrolyte secondary battery is put in a Teflon container and left in a constant temperature and humidity chamber set at a temperature of 80 ° C. and a humidity of 60% for 24 hours, and a coin cell ( (Positive electrode / separator and electrolyte / negative electrode) were prepared and the charge / discharge characteristics were evaluated in the same manner as described above, and it was confirmed that the charge capacity was 211 mAh / g and the discharge capacity was 192 mAh / g.

  Moreover, when the value of positive electrode resistance was computed like the above using the produced coin cell, it was confirmed that it was 3.4Ω.

Production conditions and evaluation results are summarized in Tables 1 and 2.
[Comparative Example 1]
(1) About the manufacturing method of the positive electrode active material for non-aqueous electrolyte secondary batteries In the same manner as in Example 1 except that the contact step and the heating step were not performed, and only the lithium nickel composite oxide manufacturing step was performed. A positive electrode active material for a non-aqueous electrolyte secondary battery was produced.

  Therefore, the obtained positive electrode active material for a non-aqueous electrolyte secondary battery is not formed with a film on the surface of the lithium nickel composite oxide particles, and no film is formed on the surface.

  The amount of carbon contained in the obtained positive electrode active material for a non-aqueous electrolyte secondary battery was measured by a high-frequency combustion infrared absorption method using a carbon analyzer (manufactured by LECO, model number: CS-600) to be 0.09 mass. %Met.

Moreover, when the positive electrode active material for non-aqueous electrolyte secondary batteries was also analyzed by ICP emission analysis, it was confirmed that the boron content was less than the detection limit, that is, less than 0.01% by mass. It was also confirmed that the silicon content was less than the detection limit, that is, less than 0.02% by mass.
(2) Evaluation Results Coin cells (positive electrode / separator and electrolyte / negative electrode) using the obtained positive electrode active material for a nonaqueous electrolyte secondary battery as a positive electrode were prepared, and charge / discharge characteristics were evaluated. When the C rate was set to 0.05 C and the battery was charged to a cutoff voltage of 4.3 V and then discharged to a cutoff voltage of 3.0 V, the charge capacity was 217 mAh / g and the discharge capacity was 197 mAh / g. I was able to confirm that.

  Moreover, when the value of positive electrode resistance was computed like the above using the produced coin cell, it was confirmed that it was 1.8Ω.

  Next, the positive electrode active material for a non-aqueous electrolyte secondary battery is put in a Teflon container and left in a constant temperature and humidity chamber set at a temperature of 80 ° C. and a humidity of 60% for 24 hours, and a coin cell ( (Positive electrode / separator and electrolyte / negative electrode) were prepared and the charge / discharge characteristics were evaluated in the same manner as described above, and it was confirmed that the charge capacity was 191 mAh / g and the discharge capacity was 175 mAh / g.

  Moreover, when the value of positive electrode resistance was computed like the above using the produced coin cell, it was confirmed that it was 3.4Ω.

Production conditions and evaluation results are summarized in Tables 1 and 2.
[Comparative Example 2]
(1) About the manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries It does not carry out a heating process, It carries out similarly to Example 1 except having implemented only the lithium nickel complex oxide manufacturing process and the contact process, A positive electrode active material for a non-aqueous electrolyte secondary battery was produced.

  Accordingly, the positive electrode for a non-aqueous electrolyte secondary battery in which a region containing boron, lithium, and oxygen is formed on the surface of the lithium nickel composite oxide particles as a coating covering the lithium nickel composite oxide particles. An active material was produced.

  The amount of carbon contained in the obtained positive electrode active material for a non-aqueous electrolyte secondary battery was measured by a high-frequency combustion infrared absorption method using a carbon analyzer (manufactured by LECO, model number: CS-600) to find 0.11 mass. %Met.

Moreover, when the positive electrode active material for non-aqueous electrolyte secondary batteries was also analyzed by ICP emission analysis, it was confirmed that the boron content was 0.05% by mass. Moreover, about silicon content, it has confirmed that it was less than a detection limit, ie, less than 0.02 mass%.
(2) Evaluation Results Coin cells (positive electrode / separator and electrolyte / negative electrode) using the positive electrode active material for a non-aqueous electrolyte secondary battery as a positive electrode were prepared, and charge / discharge characteristics were evaluated. When the C rate was set to 0.05 C and the battery was charged to a cut-off voltage of 4.3 V and then discharged to a cut-off voltage of 3.0 V, the charge capacity was 220 mAh / g and the discharge capacity was 192 mAh / g. I was able to confirm.

  Moreover, when the value of positive electrode resistance was computed like the above using the produced coin cell, it was confirmed that it was 2.3Ω.

  Next, the positive electrode active material for a non-aqueous electrolyte secondary battery is put in a Teflon container and left in a constant temperature and humidity chamber set at a temperature of 80 ° C. and a humidity of 60% for 24 hours, and a coin cell ( (Positive electrode / separator and electrolyte / negative electrode) were prepared and the charge / discharge characteristics were evaluated in the same manner as described above, and it was confirmed that the charge capacity was 197 mAh / g and the discharge capacity was 172 mAh / g.

  Moreover, when the value of positive electrode resistance was computed like the above using the produced coin cell, it was confirmed that it was 4.7Ω.

Production conditions and evaluation results are summarized in Tables 1 and 2.
[Comparative Example 3]
(1) About the manufacturing method of the positive electrode active material for non-aqueous electrolyte secondary batteries It is the same as that of Example 2 except not performing the heating process but performing only the lithium nickel composite oxide manufacturing process and the contact process. A positive electrode active material for a non-aqueous electrolyte secondary battery was produced.

  Accordingly, a positive electrode for a non-aqueous electrolyte secondary battery in which a region containing silicon, lithium, and oxygen is formed as a coating covering the lithium nickel composite oxide particles on the surface of the lithium nickel composite oxide particles. An active material was produced.

  The amount of carbon contained in the obtained positive electrode active material for a non-aqueous electrolyte secondary battery was measured by a high-frequency combustion infrared absorption method using a carbon analyzer (manufactured by LECO, model number: CS-600) to find 0.16 mass. %Met.

Moreover, when the positive electrode active material for non-aqueous electrolyte secondary batteries was also analyzed by ICP emission analysis, it was confirmed that the boron content was less than the detection limit, that is, less than 0.01% by mass. Moreover, it has confirmed that content of silicon was 0.07 mass%.
(2) Evaluation Results Coin cells (positive electrode / separator and electrolyte / negative electrode) using the positive electrode active material for a non-aqueous electrolyte secondary battery as a positive electrode were prepared, and charge / discharge characteristics were evaluated. When the C rate was set to 0.05 C and the battery was charged to a cutoff voltage of 4.3 V and then discharged to a cutoff voltage of 3.0 V, the charge capacity was 221 mAh / g, and the discharge capacity was 193 mAh / g. I was able to confirm.

  Moreover, when the value of positive electrode resistance was computed like the above using the produced coin cell, it was confirmed that it was 2.2 (ohm).

  Next, the positive electrode active material for a non-aqueous electrolyte secondary battery is put in a Teflon container and left in a constant temperature and humidity chamber set at a temperature of 80 ° C. and a humidity of 60% for 24 hours, and a coin cell ( (Positive electrode / separator and electrolyte / negative electrode) were prepared and the charge / discharge characteristics were evaluated in the same manner as described above, and it was confirmed that the charge capacity was 210 mAh / g and the discharge capacity was 185 mAh / g.

  Moreover, when the value of positive electrode resistance was computed like the above using the produced coin cell, it was confirmed that it was 3.7Ω.

Production conditions and evaluation results are summarized in Tables 1 and 2.
[Comparative Example 4]
(1) Method for producing positive electrode active material for non-aqueous electrolyte secondary battery Positive electrode for non-aqueous electrolyte secondary battery in the same manner as in Example 2 except that the heating step was performed in an oxygen stream at 500 ° C. for 1 hour. An active material was produced.

  Accordingly, a positive electrode for a non-aqueous electrolyte secondary battery in which a region containing silicon, lithium, and oxygen is formed as a coating covering the lithium nickel composite oxide particles on the surface of the lithium nickel composite oxide particles. An active material was produced.

  The amount of carbon contained in the obtained positive electrode active material for a non-aqueous electrolyte secondary battery was measured by a high-frequency combustion infrared absorption method using a carbon analyzer (manufactured by LECO, model number: CS-600) to be 0.07 mass. %Met.

Moreover, when the positive electrode active material for non-aqueous electrolyte secondary batteries was also analyzed by ICP emission analysis, it was confirmed that the boron content was less than the detection limit, that is, less than 0.01% by mass. Moreover, it has confirmed that content of silicon was 0.07 mass%.
(2) Evaluation Results Coin cells (positive electrode / separator and electrolyte / negative electrode) using the positive electrode active material for a non-aqueous electrolyte secondary battery as a positive electrode were prepared, and charge / discharge characteristics were evaluated. When the C rate was set to 0.05 C and the battery was charged to a cutoff voltage of 4.3 V and then discharged to a cutoff voltage of 3.0 V, the charge capacity was 220 mAh / g and the discharge capacity was 192 mAh / g. I was able to confirm.

  Moreover, when the value of positive electrode resistance was computed like the above using the produced coin cell, it was confirmed that it was 2.4Ω.

  Next, the positive electrode active material for a non-aqueous electrolyte secondary battery is put in a Teflon container and left in a constant temperature and humidity chamber set at a temperature of 80 ° C. and a humidity of 60% for 24 hours, and a coin cell ( (Positive electrode / separator and electrolyte / negative electrode) were prepared and the charge / discharge characteristics were evaluated in the same manner as described above, and it was confirmed that the charge capacity was 210 mAh / g and the discharge capacity was 187 mAh / g.

  Moreover, when the value of positive electrode resistance was computed like the above using the produced coin cell, it was confirmed that it was 3.6Ω.

  Production conditions and evaluation results are summarized in Tables 1 and 2.

The coin cell using the positive electrode active material for non-aqueous electrolyte secondary battery produced in Examples 1 and 2 as the positive electrode had a weather resistance higher than that of the coin cell using the positive electrode active material for non-aqueous electrolyte secondary battery of Comparative Example 1 as the positive electrode. It can be confirmed that a high charge capacity and discharge capacity are obtained after the property test. That is, the weather resistance of the positive electrode active material is improved by having a lithium nickel composite oxide particle and a positive electrode active material having a boron-containing region and a carbon content of 0.06% by mass or less. That is, it was confirmed that the deterioration of charge / discharge characteristics due to exposure to a high temperature and high humidity environment could be suppressed.

  Further, when the corresponding examples and comparative examples, specifically, Example 1 and Comparative Example 2, and Example 2 and Comparative Example 3 are compared with each other only in the presence or absence of heat treatment, the positive electrode actives of Examples 1 and 2 are compared. While the substance has a carbon content of 0.06% by mass or less, it can be confirmed that the positive electrode active materials of Comparative Examples 2 and 3 have a carbon content exceeding 0.06% by mass. And about the coin cell which used the positive electrode active material of Example 1, 2 whose carbon amount is 0.06 mass% or less for a positive electrode, the positive electrode active material of the comparative examples 2 and 3 whose carbon amount exceeds 0.06 mass% It was confirmed that a high charge capacity and a high discharge capacity were obtained even after the weather resistance test, as compared with the coin cell using as the positive electrode. Furthermore, it has also been confirmed that the carbon content of the positive electrode active material can be reduced by carrying out the contact step.

2 Particles of lithium nickel composite oxide 4 One or more compounds selected from boron compounds, phosphorus compounds, and silicon compounds

Claims (7)

General formula: Li _x Ni _1-yz Co _y Al _z O ₂ (0.90 ≦ x ≦ 1.20, 0.01 ≦ y ≦ 0.20, 0.01 ≦ z ≦ 0.10) One or more selected from boron (B), phosphorus (P), and silicon (Si) disposed on at least part of the surface of the lithium nickel composite oxide particles And a region containing lithium (Li) and oxygen (O),
A positive electrode active material for a non-aqueous electrolyte secondary battery having a carbon content of 0.06% by mass or less.   2. The positive electrode for a nonaqueous electrolyte secondary battery according to claim 1, wherein the particles of the lithium nickel composite oxide are composed of secondary particles in which primary particles are aggregated, and the average particle diameter of the secondary particles is 3 μm or more and 20 μm or less. Active material.   The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the content of boron (B) is 0.01 mass% or more and 0.10 mass% or less.   The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein the content of phosphorus (P) is 0.01 mass% or more and 0.10 mass% or less.   The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein the content of silicon (Si) is 0.05% by mass or more and 0.30% by mass or less. General formula: Li _x Ni _1-yz Co _y Al _z O ₂ (0.90 ≦ x ≦ 1.20, 0.01 ≦ y ≦ 0.20, 0.01 ≦ z ≦ 0.10) A contact step in which particles of the lithium nickel composite oxide to be contacted with a gas containing at least one compound selected from a boron compound, a phosphorus compound, and a silicon compound;
The manufacturing method of the positive electrode active material for non-aqueous electrolyte secondary batteries which has a heating process which heat-processes the obtained substance at the temperature of 600 to 800 degreeC after the said contact process. The boron compound is one or more selected from trimethyl borate and triethyl borate;
The phosphorus compound is at least one selected from trimethyl phosphite, triethyl phosphite, trimethyl phosphate, triethyl phosphate, and dimethyl phosphate;
The silicon compound is one or more selected from dimethoxydimethylsilane, trimethoxysilane, trimethoxymethylsilane, tetramethyl orthosilicate, vinyltrimethoxysilane, triethoxymethylsilane, tetraethyl orthosilicate, and 3-aminopropyltrimethoxysilane. The manufacturing method of the positive electrode active material for non-aqueous electrolyte secondary batteries of Claim 6 which exists.