JP2003346797A - Non-aqueous electrolyte secondary battery using nickel- lithium compound oxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-aqueous electrolyte secondary battery that has large discharge capacity and excellent charge and discharge cycle characteristics. <P>SOLUTION: A non-aqueous electrolyte secondary battery which has large discharge capacity and excellent charge and discharge cycle characteristics is obtained by using as a positive electrode active material a lithium-nickel compound oxide that is expressed by the formula [Li<SB>x</SB>Mg<SB>a</SB>]<SB>3b</SB>Ni<SB>1-y-z</SB>Co<SB>y</SB>M<SB>z</SB>O<SB>2</SB>(wherein 0.05≤x≤1.10, 0.01≤a≤0.05, 0.05≤y≤0.20, 0≤z≤0.10, M is at least one kind of metal selected from Al, Mg, Ti, Mn, and the suffix letter of [] expresses a site in the crystal of a hexagonal system layered rock-salt structure belonging to R-3m space group). <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonaqueous electrolyte secondary battery using a positive electrode active material having an improved composition.

[0002]

2. Description of the Related Art A positive electrode containing a positive electrode active material that reversibly electrochemically reacts with lithium ions, a negative electrode containing a negative electrode active material capable of reversibly storing and releasing lithium ions, and a non-aqueous solution containing lithium salts Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries made of electrolyte have high energy density and excellent charge / discharge cycle characteristics, so they can be used in portable wireless phones, portable personal computers, portable video cameras, and other portable batteries. It can be widely used as a power source for equipment.

As the positive electrode active material, hexagonal LiNiO ₂ having a layered rock salt structure has been widely studied in recent years because of its large discharge capacity.

[0004] However, when lithium ions are desorbed from the crystal lattice during charging, the crystallinity of LiNiO ₂ is reduced due to the cooperative Jahn-Teller distortion caused by nickel ions, and the LiNiO ₂ transitions to a crystal phase which is difficult to charge and discharge. . As a result, there is a problem that sufficient charge / discharge cycle characteristics cannot be obtained because the conductive path is disconnected.

In order to solve the above problem, Japanese Patent Application Laid-Open No.
No. 25980, LiNiO ₂ contains lithium,
By adding a metal species other than nickel to the lithium-nickel transition metal composite oxide, it suppresses the cooperative Jahn-Teller distortion and stabilizes the crystal structure of the lithium-nickel transition metal composite oxide. Attempts to improve the cycle characteristics have been proposed.

However, although the charge / discharge cycle characteristics have been improved by using the above-mentioned method, the effect has not been sufficient. This is considered for the following reason. As described above, the LiNiO ₂ crystal has a layered rock salt structure, and in this layered rock salt structure, oxygen layers having a large charge density are adjacent to each other. Therefore, at the time of charging in which lithium ions, which are cations, desorb from the interlayer, the interlayer distance increases due to the electrostatic repulsion between the oxygen and anions. Conversely, at the time of discharging, lithium ions are inserted between the layers, and as a result, the interlayer distance contracts due to electrostatic attraction between lithium cations and oxygen anions. Due to such expansion and contraction of the interlayer distance due to charge and discharge, the crystal structure itself is collapsed, and the primary particles are separated from the secondary particles of the positive electrode active material. It is thought to decline. It is considered that the enlargement / shrinkage of the interlayer distance cannot be suppressed by the above-described method, so that the improvement of the charge / discharge cycle characteristics is insufficient.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a non-aqueous electrolyte secondary battery having a large discharge capacity and excellent charge / discharge cycle characteristics. To provide.

[0008]

Means for Solving the Problems and Action / Effect The invention according to claim 1 is a non-aqueous electrolyte secondary battery having a positive electrode containing a positive electrode active material, a negative electrode, and a non-aqueous electrolyte, wherein the positive electrode active material is [ _{li x Mg a] 3b Ni 1} -y- z Co y M z O
₂ (0.05 ≦ x ≦ 1.10, 0.01 ≦ a ≦ 0.0
5, 0.05 ≦ y ≦ 0.20, 0 ≦ z ≦ 0.10, M is at least one kind of metal selected from the group consisting of Al, Mg, Ti, and Mn. A lithium-nickel composite oxide represented by a hexagonal layered rock-salt type crystal belonging to a space group of −3 m).

First, a non-aqueous electrolyte secondary battery having a large discharge capacity can be obtained by using a lithium nickel composite oxide as the positive electrode active material.

Next, C is added to the lithium nickel composite oxide.
By containing o and M (at least one metal selected from the group consisting of Al, Mg, Ti and Mn), a cooperative yarn caused by nickel ions generated when lithium ions desorb from a crystal lattice during charging・ Teller distortion can be suppressed, and transition to a crystal phase that is difficult to charge and discharge can be suppressed. As a result, charge / discharge cycle characteristics can be improved.

When the value of y indicating the ratio of cobalt ions is 0.
If it is less than 05, the cooperative yarn-Teller distortion cannot be suppressed, and as a result, the crystal structure cannot be stabilized. On the other hand, if the value of y exceeds 0.20, cobalt has a smaller reserve amount and is more expensive than nickel, and therefore is not preferable from the viewpoint of material procurement and cost merit. Further, since the ratio of nickel ions relatively decreases, the discharge capacity also decreases, which is not preferable. Therefore, the value of y is preferably 0.05 or more and 0.20 or less.

If the value of z indicating the ratio of the metal M other than lithium and cobalt exceeds 0.10, the discharge capacity is undesirably reduced, which is not preferable. Therefore, the value of z is 0.1
0 or less is preferable.

Further, since the 3b site is occupied by magnesium ions, a nonaqueous electrolyte secondary battery having excellent charge / discharge cycle characteristics can be obtained. this is,
It is considered as follows.

In the case of a hexagonal compound, among the specific locations occupied by atoms in the crystal, sites which collectively include crystallographically equivalent atomic positions include 3a sites and 3b sites.
Site and 6c site. When LiNiO ₂ has a perfect stoichiometric composition, lithium ion is 3b site, nickel ion is 3a site, and oxygen ion is 6
Each of the c sites is occupied at a site occupancy of 100%. When magnesium ions occupy the 3b site that is originally occupied by lithium ions, Mg ²⁺ relaxes the electrostatic repulsion between the oxygen and anion layers, and the expansion and contraction of the interlayer distance during charging and discharging can be suppressed. As a result, the crystal structure of the positive electrode active material can be stabilized, for example, by preventing the collapse of the crystal structure and preventing the primary particles from peeling off from the secondary particles of the positive electrode active material. It will improve.

If the value of a, which represents the proportion of magnesium ions occupying the 3b site, is less than 0.01, the electrostatic repulsion between the oxygen and anion layers cannot be sufficiently reduced, so that the charge / discharge cycle characteristics deteriorate. On the other hand, when a is 0.
If it exceeds 05, the 3b site mixed with Mg ²⁺ becomes electrochemically inactive, so that the discharge capacity decreases, which is not preferable. From the above, the value of a is 0.01 ≦ a ≦ 0.
05 is preferred.

When the value of x indicating the ratio of lithium ions is 0.1.
When the battery is charged to a value smaller than 05, it becomes difficult to electrochemically extract lithium ions while maintaining the layered rock salt type structure. Further, if the discharge is performed until the value of x exceeds 1.10, the change in the crystal structure becomes large, and the charge / discharge cycle characteristics are undesirably reduced. Therefore, the value of x is preferably 0.05 or more and 1.10 or less.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a positive electrode active material is used.
In general, the positive electrode active material has the general formula [Li_xMg_a] _3bNi
_1-yzCo_yM_zO₂(0.05 ≦ x ≦ 1.10,
0.01 ≦ a ≦ 0.05, 0.05 ≦ y ≦ 0.20, 0
≤ z ≤ 0.10)
Titanium nickel composite oxide is used. M is Al, M
at least one selected from the group consisting of g, Ti, and Mn
Of these, Al is preferable. Attached to []
The letter "H" is a hexagonal layered rock salt belonging to the R-3m space group.
The site | part in the crystal | crystallization of a type structure is shown.

The lithium-nickel composite oxide is synthesized by mixing a lithium source, a magnesium source, a nickel source, a cobalt source, and a transition metal source and firing the mixture in the air or under an oxygen atmosphere. In order to synthesize a lithium nickel composite oxide in which magnesium ions are appropriately introduced into the 3b site, the calcination temperature is 650 ° C to 8 ° C.
00 ° C. is preferable, and the firing time is preferably 5 hours to 12 hours. The baking time is preferably short when the baking temperature is high, and is long when the baking temperature is low.
0 hours is preferred.

If the firing temperature is lower than 650 ° C., lithium ions are not sufficiently introduced into the nickel compound, resulting in a decrease in discharge capacity. Firing temperature is 800 ° C ~ 850
In the case of ° C., the crystallinity of the lithium-nickel composite oxide becomes too high and magnesium ions are not appropriately introduced into the 3b site, so that the charge / discharge cycle characteristics deteriorate. If the firing temperature exceeds 850 ° C., excessive divalent nickel ions and divalent magnesium ions are introduced into empty sites generated by volatilization of lithium ions, and the discharge capacity is significantly reduced.

As the lithium source, for example, lithium nitrate, lithium sulfate, lithium chloride, lithium bromide, lithium iodide, lithium hydroxide, lithium oxide, lithium peroxide, lithium carbonate, lithium formate, lithium acetate,
Examples include lithium benzoate, lithium citrate, lithium oxalate, lithium pyruvate, lithium stearate, lithium tartrate, and the like.

Examples of the nickel source include nickel hydroxide, nickel oxide, nickel carbonate, nickel nitrate, nickel chloride, nickel sulfate, nickel acetate, nickel oxyhydroxide and the like.

As a cobalt source, for example, cobalt hydroxide, cobalt oxide, cobalt carbonate, cobalt nitrate,
Examples thereof include cobalt chloride, cobalt sulfate, cobalt acetate, and cobalt oxyhydroxide.

Examples of the magnesium source include magnesium hydroxide, magnesium oxide, magnesium carbonate, magnesium nitrate, magnesium chloride, magnesium sulfate, and magnesium acetate.

As the compound containing the metal M, nitrate, lead sulfate, carbonate, acetate, hydroxide, oxide, chloride and the like of the metal M can be used.

The lattice constant and the site occupancy of each atom in the lithium nickel composite oxide can be determined by Rietveld analysis of the diffraction pattern obtained by the powder X-ray diffraction method (for example, “The Rietveld Method,” ed. By RA Young, Oxfo
rd University Press, Oxford (1993).) The Rietveld analysis is a method of refining parameters related to a crystal structure by fitting a powder diffraction pattern using X-rays and neutrons with a diffraction pattern calculated based on an assumed structural model.

The lithium nickel composite oxide obtained as described above, a conductive agent and a binder are mixed to prepare a positive electrode mixture, and this positive electrode mixture is mixed with a positive electrode current collector made of a metal foil. The positive electrode can be manufactured by applying the composition to the positive electrode.

The type of the conductive agent is not particularly limited, and may be metal or nonmetal. As a metal conductive agent,
Materials composed of metal elements such as Cu and Ni can be given. Examples of the nonmetallic conductive agent include carbon materials such as graphite, carbon black, acetylene black, and Ketjen black.

The type of the binder is not particularly limited as long as it is a material that is stable with respect to the solvent and the electrolyte used in the production of the electrode. Specifically, polyethylene, polypropylene,
Polyethylene terephthalate, aromatic polyamide, cellulose, styrene-butadiene rubber, isoprene rubber,
Butadiene rubber, ethylene-propylene rubber, styrene-butadiene-styrene block copolymer and hydrogenated product thereof, styrene-ethylene-butadiene-styrene block copolymer and hydrogenated product thereof, styrene-isoprene-styrene block copolymer and The hydrogenated product, syndiotactic 1,2-polybutadiene, ethylene-vinyl acetate copolymer, propylene-α-olefin (C 2-12) copolymer, polyvinylidene fluoride, polytetrafluoroethylene, polytetrafluoro An ethylene-ethylene copolymer or the like can be used.

The positive electrode current collector includes, for example, Al, Ta, N
Examples thereof include b, Ti, Hf, Zr, Zn, W, Bi, and alloys including these metals. Since these metals form a passive film on the surface by anodic oxidation in the electrolyte, it is possible to effectively prevent the non-aqueous electrolyte from being oxidatively decomposed at the liquid contact portion between the positive electrode current collector and the electrolyte. it can. As a result, the cycle characteristics of the non-aqueous secondary battery can be effectively improved.

Examples of the negative electrode active material include lithium metal, lithium alloys such as lithium-aluminum alloy, lithium-lead alloy, and lithium-tin alloy, which can absorb and release lithium, and Li ₅ (Li ₃ N). Lithium nitride, graphite, coke, pyrolytic carbons, carbon on glass,
Carbon materials such as calcined organic polymer compounds, mesocarbon microbeads, carbon fiber, activated carbon, WO ₂ , MoO
₂ , SnO ₂ , SnO, TiO ₂ , SiO ₂ , NbO ₃
For example, a transition metal oxide such as One of these negative electrode active materials may be selected and used, or two or more thereof may be used in combination.

As the material of the negative electrode current collector, metals such as copper, nickel, and stainless steel can be used.

The method for producing the negative electrode is not particularly limited, and the negative electrode can be produced by the same method as the above-described method for producing the positive electrode.

The electrolyte salt of the non-aqueous electrolyte is LiCl
Inorganic lithium salts such as O ₄ , LiAsF ₆ , LiPF ₆ , LiBF _{4 and the} like, LiCF ₃ SO ₃ , LiN (CF ₃ SO
₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiC
Fluorinated organic lithium salts such as (CF ₃ SO ₂ ) _{3 and the} like can be mentioned. One of these solutes may be selected and used, or two or more may be used in combination.

As the electrolyte, a solid or gel electrolyte can be used in addition to the above-mentioned electrolyte. Examples of such an electrolyte include, in addition to an inorganic solid electrolyte, polyethylene oxide, polypropylene oxide, and derivatives thereof.

As the separator, a material obtained by impregnating an electrolytic solution into a microporous polyethylene film, a microporous polypropylene film, a nonwoven fabric of polyethylene, a nonwoven fabric of polypropylene, or the like can be used. Further, a polymer solid electrolyte or a gel electrolyte in which an electrolyte solution is contained in a polymer solid electrolyte can also be used. Further, an insulating microporous film and a solid polymer electrolyte may be used in combination. When a porous solid polymer electrolyte membrane is used as the solid polymer electrolyte, the electrolyte contained in the polymer and the electrolyte contained in the pores may be different.

Hereinafter, the present invention will be described in detail with reference to examples. Since what is essential in the present invention is the positive electrode active material, the charge / discharge cycle characteristics of only this positive electrode active material were measured using a single electrode cell. The present invention is not limited by the following examples. <Examples 1 to 11 and Comparative Examples 1 to 5> After various metal components were mixed at the atomic ratios shown in Table 1, the mixture was fired in an oxygen stream at the firing temperature and firing time shown in Table 1. Thus, the lithium nickel composite oxides in Examples 1 to 11 and Comparative Examples 1 to 5 were prepared.

[0037]

[Table 1]

<Measurement> (X-ray Diffraction Measurement Method and Rietveld Analysis) The synthesized sample was subjected to X-ray diffraction measurement using RINT2400 manufactured by Rigaku Corporation. The X-ray source was CuKα (wavelength λ = 1.5405 °), the tube voltage was 50 kV, the current was 200 mA, the divergence slit was 1.0 °, the scattering slit was 1.0 °, and the light receiving slit was 0.15 mm. The measured reflection angle is 10 ° ≦ 2θ ≦ 100 °, and the scanning angle is 0.0
Measured at 2 °. The reflection peak of the obtained X-ray diffraction was subjected to processes such as background removal and Kα2 removal. The removal of the Kα2 peak is Kα2 / Kα1 = 0.49.
8 was performed. For the obtained X-ray diffraction results, RI
Rietveld analysis was performed using ETAN-2000 (Mr. Fujio Izumi) to determine the site occupancy of each metal element component. In particular, when obtaining the element occupancy other than lithium at the 3b site, the (003) plane diffraction peak was accurately obtained from the obtained X-ray analysis results. The obtained site occupancy is summarized in Tables 2 and 3.

In Example 3 and Comparative Examples 1 and 3, the lithium ion site occupancy and the lattice constants a and c in different discharge states were obtained by Rietveld analysis under the same conditions as described above. Was. FIG. 2 shows the relationship between the lattice constant a and the site occupancy of lithium ions, and FIG. 3 shows the relationship between the lattice constant c and the site occupancy of lithium ions. Here, the site occupancy of lithium ions is used as an index indicating the discharge state of the positive electrode active material, since lithium ions are desorbed and inserted from the crystal of the positive electrode active material during charge and discharge.

(Preparation of Single Electrode) The positive electrode active material obtained as described above was subjected to a single electrode test as follows. The positive electrode plate was prepared by mixing powder of the above-mentioned positive electrode active material, 5% acetylene black as a conductive additive, polyvinylidene fluoride as a binder, and N-methylpyrrolidone as a solvent to form a paste. After coating on an aluminum mesh as an electrical conductor, it was dried at 80 ° C.
It was manufactured by performing vacuum drying at 30 ° C. for 5 hours. Metal lithium is used for the counter and reference electrodes, and ethylene carbonate (EC) and diethyl carbonate (DEC) are used as the electrolyte.
A mixture obtained by adding LiClO ₄ to the mixture was used.

(Evaluation) A charge / discharge test was performed using this cell. The charge and discharge conditions, the charge is up to 4.3V at 1.0 mA / cm ² constant current discharge was set to 3.0V at 1.0 mA / cm ² constant current was carried out 50 cycles this as one cycle. Then, the discharge capacities at the first cycle and the 50th cycle are obtained, and 5 times the discharge capacity at the first cycle.
The ratio of the discharge capacity at the 0th cycle was determined, and this was defined as the capacity retention (%). These are summarized in Tables 2 and 3.
FIG. 4 shows the relationship between the discharge capacity and the number of cycles in Examples 3 and 6 and Comparative Examples 1 and 3 among the obtained results.
Shown in

[0042]

[Table 2]

[0043]

[Table 3]

<Results> (Composition of Positive Electrode Active Material) As a result of Rietveld analysis of the synthesized samples, each sample was found to contain various metal ions at the site occupancy as shown in Tables 2 and 3. Do you get it.

FIG. 2 shows that Example 3 has a smaller change width of the crystal lattice c in the c-axis direction during the charge / discharge cycle than Comparative Example 1. In the lithium nickel composite oxide having a layered rock salt structure, the lithium layers are stacked in the c-axis direction. Therefore, the above result means that the variation width of the interlayer distance is smaller in Example 3 than in Comparative Example 1. It is considered that this is because magnesium ions occupying the 3b site suppressed expansion and contraction of the interlayer distance of the crystal due to charge and discharge.

FIG. 3 shows that there was no difference between Example 3 and Comparative Examples 1 and 3 regarding the crystal lattice a in the a-axis direction. Thus, it was found that even if the 3b site was occupied by magnesium ions, it did not affect the a-axis direction.

As shown in Table 2, the batteries of Examples 1 to 7 in which the occupancy of magnesium ions occupying the 3b site is 0.01 or more and 0.05 or less are compared with those in which the occupancy of magnesium ions is 0. As compared with Example 1, excellent charge / discharge cycle characteristics were exhibited. This is presumably because, as described above, the magnesium ions occupying the 3b site suppress the expansion and contraction of the lithium interlayer distance due to charge and discharge.

The batteries of Examples 1 to 5 correspond to 3b
As compared with Comparative Examples 2 and 3 in which the occupation ratios of magnesium ions in the sites were 0.06 and 0.12. This is considered to be because when the 3b site is occupied by magnesium ions, that portion becomes electrically inactive.

FIG. 4 shows Examples 3 and 6 and Comparative Examples 1 and 3.
For each sample, a graph of the discharge capacity with respect to the number of cycles was shown. In Examples 3 and 6, the discharge capacity hardly decreased even when the number of cycles increased. On the other hand, in Comparative Example 1, although the initial discharge capacity was larger than Examples 3 and 6, the discharge capacity was significantly reduced with an increase in the number of cycles. In Comparative Example 3, the initial discharge capacity was also lower than in Examples 3 and 6, and the decrease in the discharge capacity with the increase in the number of cycles was large.

As described above, since the occupation ratio of magnesium ions occupying the 3b site is 0.01 or more and 0.05 or less, a nonaqueous electrolyte secondary battery having a large discharge capacity and excellent charge / discharge cycle characteristics is provided. I found that I could get.

On the other hand, as shown in Table 3, in Examples 8 to 11 in which the site occupancy of the cobalt ions occupying the 3a site is 0.05 or more and 0.20 or less, the site occupancy of the cobalt ions is 0.1 to 0.20. In comparison with Comparative Example 4, which was No. 04, the charge / discharge cycle characteristics were excellent. This is considered to be due to the suppression of the cooperative yarn-Teller distortion by the addition of cobalt ions.

In Comparative Example 5 in which the site occupancy of cobalt ions was 0.21, the discharge capacity was lower than those in Examples 8 to 11, and the cost of raw materials was high because cobalt was expensive. Not preferred. From this, the nonaqueous electrolyte secondary battery having a large discharge capacity and excellent charge / discharge cycle characteristics because the site occupancy of the cobalt ions occupying the 3a site is 0.05 or more and 0.20 or less. Can be obtained.

<Summary> As described above, in the nonaqueous electrolyte secondary battery including the positive electrode including the positive electrode active material, the negative electrode, and the nonaqueous electrolyte, the positive electrode active material is [Li _x Mg _a ] _3b Ni
_{1-y-z Co y M} z O 2 (0.05 ≦ x ≦ 1.10,
0.01 ≦ a ≦ 0.05, 0.05 ≦ y ≦ 0.20, 0
≦ z ≦ 0.10, M is at least one metal selected from the group consisting of Al, Mg, Ti, and Mn, and the subscript in [] indicates a hexagonal layered rock salt belonging to the space group of R-3m. (Indicating a site in a crystal having a type structure), it is possible to obtain a non-aqueous electrolyte secondary battery having a large discharge capacity and excellent charge / discharge cycle characteristics. all right.

<Other Embodiments> The present invention is not limited to the embodiments described with reference to the above description and the drawings. For example, the present invention can be used as a normal battery in combination with a negative electrode, a separator, and the like by a conventional method. . In that case, the battery structure is not particularly limited, square, cylindrical, bag-like,
Of course, a lithium polymer battery or the like may be used. Furthermore, various changes other than the above can be made without departing from the scope of the invention.

[0055]

According to the present invention, a non-aqueous electrolyte secondary battery having a large discharge capacity and excellent charge / discharge cycle characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a crystal structure of a lithium nickel composite oxide belonging to a hexagonal R-3m space group.

FIG. 2 is a graph showing a relationship between a lattice constant in the c-axis direction of a positive electrode active material according to an example of the present invention and a site occupancy of lithium ions.

FIG. 3 is a graph showing the relationship between the lattice constant in the a-axis direction of the positive electrode active material according to the example of the present invention and the site occupancy of lithium ions.

FIG. 4 is a graph showing charge / discharge cycle characteristics of a positive electrode active material according to an example of the present invention.

   ────────────────────────────────────────────────── ─── Continuation of front page    F term (reference) 4G048 AA04 AA05 AB06 AC06 AD06                       AE05                 5H029 AJ03 AJ05 AK03 AL12 AM05                       AM07 EJ01 EJ04 EJ11 EJ12                       HJ02                 5H050 AA07 AA08 BA17 CA07 CB02                       CB07 CB08 CB09 CB12 EA02                       EA10 EA11 EA21 EA24 HA02

Claims (1)

[Claims] 1. A non-aqueous electrolyte secondary battery including a positive electrode including a positive electrode active material, a negative electrode, and a non-aqueous electrolyte, wherein the positive electrode active material is [Li _x Mg _a ] _3b Ni _{1-y -z} Co _y
M _z O ₂ (0.05 ≦ x ≦ 1.10, 0.01 ≦ a ≦
0.05, 0.05 ≦ y ≦ 0.20, 0 ≦ z ≦ 0.1
0 and M are at least one metal selected from the group consisting of Al, Mg, Ti, and Mn.
A lithium-nickel composite oxide represented by a hexagonal layered rock-salt type crystal belonging to a space group of −3 m).