JPH0935712A - Positive electrode active material, its manufacture and nonaqueous electrolyte secondary battery using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery in which the lowering of cycle capacity is small at a high temperature and which has excellent storage performance by replacing Mn with transition metals selected from Co, Ni, Fe, V, Cr and Ti in the surface of a positive electrode active material. SOLUTION: A positive electrode active material used for a nonaqueous electrolyte secondary battery, in the surface, is a spinel lithium manganese oxide in which Mn is replaced with at least either one transition metal selected from Co, Ni, Fe, V, Cr and Ti. Almost all parts except the surface are formed of LiMn2 O4 . It is preferable that the molar fraction of Mn and transition metals is 0.99:0.01 to 0.8:0.2. The positive electrode active material is obtained by dispersing a manganese dioxide into an aqueous solution in which the salt of transition metals is dissolved and adjusting it to the alkaline side by a lithium hydroxide aqueous solution and after that, drying and solidifying it to make it into a powder in which transition metals are made to adhere to manganese dioxide and mixing lithium carbonate with it and heat-treating its mixture.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a positive electrode active material used in a non-aqueous electrolyte secondary battery and the like, a method for producing the same, and a non-aqueous electrolyte secondary battery using the same.

[0002]

2. Description of the Related Art In recent years, the development of electronic devices has been remarkable, and devices such as video cameras, compact disc players, portable headphone stereos, mobile phones, and transceivers, which are small and lightweight and are used for portable use, have been rapidly developed and put into practical use. Has been done. Especially for these portable devices, miniaturization is strongly desired, and at the same time, miniaturization of the power supply is also desired.

As a secondary battery conventionally used as a power source for these electronic devices, a lead battery, a NiCd battery and the like can be cited. However, for lead batteries and NiCd batteries,
The energy density per weight is small, and sufficient capacity cannot be obtained when the size is reduced. In addition, since the cycle performance with respect to the load used during charging / discharging is insufficient, there is the inconvenience of having to carry a spare power supply in addition to the power supply used. Furthermore, since these batteries have a low energy density per weight, the battery weight is also heavy, and it cannot be said that they are suitable for carrying.

Therefore, as a secondary battery having a high energy density, lithium, a lithium alloy, or a carbon material capable of doping / dedoping lithium ions is used as a negative electrode material, and lithium cobalt oxide, lithium nickel oxide, etc. The research and development of non-aqueous electrolyte secondary batteries using as a positive electrode material have been actively conducted.

This non-aqueous electrolyte secondary battery has an operating voltage of 3
It is as high as ˜4 V, can achieve high energy density, has less self-discharge, and has significantly improved cycle performance as compared with conventional batteries.

By the way, in non-aqueous electrolyte secondary batteries, lithium cobalt oxide and lithium nickel oxide are mainly used as positive electrode materials, but compounds containing cobalt and nickel are relatively expensive and are used on an industrial level. Not suitable for.

Under these circumstances, research and development of low-priced positive electrode materials have been promoted, and manganese oxide has attracted attention.

Manganese oxide has been conventionally used as a positive electrode material in a coin type non-aqueous electrolyte battery (Li / MnO ₂ battery) for primary battery specifications.
Reversible as a material for secondary batteries. When this manganese oxide is used in, for example, a 3V-class secondary battery, the battery capacity can be secured at about 1/2 of the initial discharge, a high energy density can be obtained, and self-discharge can be suppressed to a small level, resulting in excellent performance To be

[0009]

However, when manganese oxide is used as it is as a positive electrode material, the discharge potential of the battery is limited to about 3V, and a 4V class battery cannot be realized. That is, the stability of the positive electrode material depends solely on the voltage. Here, lithium cobalt oxide, lithium nickel oxide, and the like are relatively stable against voltage, and a non-aqueous electrolyte secondary battery using them as a positive electrode material is used at a charging voltage exceeding 4V. On the contrary,
A battery using a manganese oxide, for example, spinel type lithium manganese oxide as a positive electrode material, when continuously used under the same use conditions as a non-aqueous electrolyte secondary battery using lithium cobalt oxide, etc. Performance and storage performance deteriorate rapidly. Therefore, in use, operating temperature conditions are severely limited, and it is necessary to sufficiently control voltage and time.

Therefore, the present invention has been proposed in view of such conventional circumstances, and a positive electrode active material that maintains good positive electrode performance even when continuously used at a charging voltage of 4 V or more under a high temperature environment. And its manufacturing method. Further, by using such a positive electrode active material, even when continuously used at a charging voltage of 4 V or more in a high temperature environment, a decrease in cycle capacity can be suppressed to a small level, and good storage performance can be obtained. The purpose is to provide a secondary battery.

[0011]

In order to achieve the above object, the positive electrode active material of the present invention has Co, N
It is characterized in that it is a spinel type lithium manganese oxide in which Mn is substituted by at least one kind of transition metal selected from i, Fe, V, Cr and Ti. The transition metal with which Mn is substituted includes N
i, Co and Fe are preferable.

As described above, in order to produce a spinel type lithium manganese oxide in which Mn is replaced with a transition metal on the surface, manganese dioxide is added to Co, Ni and F.
After being dispersed in an aqueous solution in which a salt of at least one kind of transition metal selected from e, V, Cr and Ti is dissolved, and the liquidity thereof is adjusted to an alkaline side with an aqueous solution of lithium hydroxide, the aqueous solution is dried and solidified. This produces a powder in which a transition metal is attached to manganese oxide. Then, this powder and lithium carbonate are mixed and heat-treated to synthesize lithium manganese oxide.

At this time, the amount of each material used is such that the molar fraction of Mn and the transition metal is 0.99: 0.01 to 0.8: 0.2.
It is desirable to set so that

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Specific embodiments of the present invention will be described below.

The positive electrode active material of the present invention has C on the surface.
It is a spinel type lithium manganese oxide in which Mn is substituted with at least one transition metal selected from o, Ni, Fe, V, Cr and Ti. That is, in this positive electrode active material, the surface is LiMn _2-y Me _y O ₂ (however, M
e is a composition of at least one kind of transition metal selected from Co, Ni, Fe, V, Cr, and Ti), and most of it except for the surface is composed of LiMn ₂ O ₄ .

Thus, the spinel type lithium manganese oxide in which Mn on the surface is replaced by a transition metal has a capacity equivalent to that of pure spinel type lithium manganese oxide and is very excellent in stability against voltage. . Therefore, in a battery using this oxide as a positive electrode active material, even when it is continuously used at a charging voltage of 4 V or higher under a high temperature environment, the decrease in cycle capacity is suppressed to a small level, and good storage performance is obtained. Furthermore, in this case, even if an expensive transition metal such as Co or Ni is selected as the substitution element, the amount used is extremely small, which is advantageous in reducing the cost of the battery.

In this spinel type lithium manganese oxide, the transition metal for substituting Mn is N.
i, Co and Fe are preferable.

In order to produce a spinel type lithium manganese oxide in which Mn on the surface is replaced by a transition metal, manganese dioxide is added to Co, Ni, Fe, V, C.
Manganese oxidation by dispersing in an aqueous solution in which a salt of at least one transition metal selected from r and Ti is dissolved, adjusting the liquidity to the alkaline side with an aqueous lithium hydroxide solution, and drying and solidifying this aqueous solution. A powder with a transition metal attached to the object is produced. Then, this powder and lithium carbonate are mixed and heat-treated to synthesize lithium manganese oxide.

At this time, the amount of each material used is preferably set so that the mole fraction of Mn and the transition metal is 0.99: 0.01 to 0.8: 0.2. If the transition metal mole fraction is less than 0.01, a sufficiently stable lithium manganese oxide with respect to voltage cannot be obtained. In addition, the lithium manganese oxide synthesized under the condition that the transition metal molar fraction exceeds 0.2 has a lower initial capacity than pure spinel-type lithium manganese oxide and has insufficient voltage stability. Is.

In the non-aqueous electrolyte secondary battery of the present invention, spinel-type lithium manganese oxide in which Mn on the surface is replaced with a transition metal as described above is used as a positive electrode active material. Any of those normally used in this type of battery can be used.

As the negative electrode active material, in addition to lithium metal and lithium alloy, a carbon material capable of doping and dedoping lithium is used. As this carbon material,
A low crystalline carbon material obtained by firing at a relatively low temperature of 2000 ° C. or lower, or a raw material that easily crystallizes is 300
A highly crystalline carbon material such as artificial graphite or natural graphite obtained by heat treatment at a high temperature near 0 ° C. is used. Specifically, pyrolytic carbons, cokes (pitch coke, needle coke, petroleum coke, etc.), graphites, glassy carbons, organic polymer compound fired bodies (furan resin, etc. are fired at an appropriate temperature to produce carbon. ), Carbon fiber, activated carbon and the like.

Further, as the electrolytic solution, an electrolytic solution in which a lithium salt is used as a supporting electrolyte and this is dissolved in an organic solvent is used.

As the organic solvent, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone,
Tetrahydrofuran, 2-methyltetrahydrofuran,
1,3-dioxolane, 4-methyl-1,3-dioxolane, sulfolane, methylsulfolane, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate and the like can be used.

As the supporting electrolyte, LiClO ₄ , Li
AsF ₆ , LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ ,
CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiN (CF ₃ S
O ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiCl, LiBr
And the like.

[0025]

EXAMPLES Examples of the present invention will be described based on experimental results.

Example 1 First, a positive electrode active material was synthesized as follows.

8.27 g of electrolytic manganese dioxide having an average particle size of 25 μm was dispersed in an aqueous solution prepared by dissolving 1.45 g of cobalt nitrate hexahydrate in 200 ml of water. While stirring this, a 1% aqueous solution of lithium hydroxide was gradually added dropwise to adjust the pH value of the solution to 9.0. Then, stirring was continued for 1 hour in this state. As a result, cobalt is attached to the manganese oxide.

Next, this solution was heated, dried and solidified to recover the powder in which cobalt was adhered to the manganese oxide, and further heat-dried at 300 ° C.
Next, 8.72 g of this powder and 1.85 g of lithium carbonate were mixed in a mortar and then put into an alumina crucible. Then, using an electric furnace, heat treatment was performed in air at a temperature of 400 ° C. for 3 hours, and then heat treatment was further performed at a temperature of 800 ° C. for 12 hours, and cooled to room temperature. When the obtained lithium manganese oxide was analyzed by an X-ray diffractometer, a spectrum whose peak position coincided with that of the spinel type lithium manganese oxide was observed.

Further, S of the lithium manganese oxide is
The spectrum observed by the EM EMAX analysis method is shown in FIG. The SEM EMAX analysis method is a method of detecting a characteristic X-ray generated when the sample surface is irradiated with an electron beam and analyzing the element contained in the sample from the peak position of the characteristic X-ray. From the spectrum of FIG. 1, a peak derived from Co appears, and it is confirmed that Co is introduced into the synthesized lithium manganese oxide.

Next, a positive electrode was prepared by using the obtained lithium manganese oxide as a positive electrode active material.

85% by weight of the lithium manganese oxide
10% by weight of graphite as a conductive agent and 5% by weight of polytetrafluoroethylene as a binder were mixed and molded into a pellet shape (disk type) having a diameter of 15 mm using a pressure press. Then, the lithium manganese oxide pellets were dried together with a Ni net (pore diameter 0.05 mm) under vacuum at a temperature of 250 ° C. for 8 hours to prepare positive electrode pellets.

On the other hand, for the negative electrode, a carbon material obtained by introducing a functional group containing oxygen (oxygen cross-linking) into petroleum pitch and then heat-treating it was prepared as a negative electrode active material.

90% by weight of the above carbon material and 10% by weight of polyvinylidene fluoride as a binder were mixed, dispersed in N-methyl-2pyrrolidone (NMP), and dried at 120 ° C. Then, this mixture is pressed with a pressure molding machine to give a diameter of 16
mm pellets, 8 at 120 ° C under vacuum
The negative electrode pellet was produced by drying for a time.

A coin type battery as shown in FIG. 2 was produced using the obtained positive electrode pellets and negative electrode pellets.

First, the positive electrode pellets 1 are put in a positive electrode can 5 made of stainless steel, a polypropylene separator 3 (trade name Celgard # 2502) is laid on the positive electrode can 1, and an insulating gasket 6 made of polypropylene is attached to the outer edge of the positive electrode can 5. I installed it. Next, an electrolyte solution in which 1 mol / l of LiPF ₆ was dissolved in an equal volume mixture of propylene carbonate and dimethyl carbonate was injected into the positive electrode pellet 1 and the negative electrode pellet 2. And
The negative electrode pellet 2 was placed on the separator 3, the negative electrode can 4 was placed thereon, and the can was caulked to manufacture a coin-type battery having a diameter of 20 mm and a height of 1.6 mm.

Example 2 A positive electrode active material was synthesized as follows.

8.27 g of electrolytic manganese dioxide having an average particle size of 25 μm was dispersed in an aqueous solution prepared by dissolving 1.45 g of nickel nitrate hexahydrate in 200 ml of water. While stirring this, a 1% aqueous solution of lithium hydroxide was gradually added dropwise to adjust the pH value of the solution to 9.0. Then, stirring was continued for 1 hour in this state.

Next, this solution was heated, dried and solidified to recover the powder in which nickel was attached to the manganese oxide, and further heat-dried at 300 ° C.
Next, 8.30 g of this powder and 1.20 g of lithium carbonate were mixed in a mortar and then put into an alumina crucible. Then, using an electric furnace, heat treatment was performed in air at a temperature of 400 ° C. for 3 hours, and then heat treatment was further performed at a temperature of 800 ° C. for 12 hours, and cooled to room temperature. When the obtained lithium manganese oxide was analyzed by an X-ray diffractometer, a spectrum whose peak position coincided with that of the spinel type lithium manganese oxide was observed.

Example 1 except that the lithium manganese oxide thus synthesized was used as the positive electrode active material.
A coin-type battery was manufactured in the same manner as in.

Example 3 A positive electrode active material was synthesized as follows.

8.27 g of electrolytic manganese dioxide having an average particle size of 25 μm was added to 200 ml of water and 2.0 g of iron nitrate hexahydrate.
Was dispersed in the dissolved aqueous solution. While stirring this, a 1% aqueous solution of lithium hydroxide was gradually added dropwise to adjust the pH value of the solution to 9.0. Then, stirring was continued for 1 hour in this state.

Then, the solution is heated, dried and solidified to recover the powder in which iron is attached to the manganese oxide,
Further, heat drying treatment was performed under the condition of 300 ° C. next,
This powder (8.63 g) and lithium carbonate (1.85 g) were mixed in a mortar and then put into an alumina crucible. Then, using an electric furnace, heat treatment was performed in air at a temperature of 400 ° C. for 3 hours, and then heat treatment was further performed at a temperature of 800 ° C. for 12 hours, and cooled to room temperature. When the obtained lithium manganese oxide was analyzed by an X-ray diffractometer, a spectrum whose peak position coincided with that of the spinel type lithium manganese oxide was observed.

Example 1 except that the lithium manganese oxide thus synthesized was used as the positive electrode active material.
A coin-type battery was manufactured in the same manner as in.

Comparative Example 1 A positive electrode active material was synthesized as follows.

8.7 g of electrolytic manganese dioxide having an average particle diameter of 25 μm and 1.85 g of lithium carbonate were mixed in a mortar and then charged into an alumina crucible. Then, using an electric furnace, heat treatment was performed in air at a temperature of 400 ° C. for 3 hours, and then heat treatment was further performed at a temperature of 800 ° C. for 12 hours, and cooled to room temperature. The obtained lithium manganese oxide is
When analyzed by a line diffractometer, a spectrum having the same peak position as that of the spinel type lithium manganese oxide was observed.

Example 1 except that the lithium manganese oxide thus synthesized was used as the positive electrode active material.
A coin-type battery was manufactured in the same manner as in.

The battery manufactured as described above was first charged for 30 hours at a current of 1 mA and an upper limit voltage of 4.2 V, and then discharged at a current of 1 mA and a final voltage of 2.5 V. Next, charging / discharging was repeated under conditions of a current of 2.5 mA, an upper limit voltage of 4.2 V, a charging time of 10 hours, and a lower limit voltage of 2.5 V, and the fifth cycle capacity and the 20th cycle capacity were measured.

Regarding the battery different from the battery used for this measurement, the latter 5 of the above-mentioned conditions were used.
After performing cycle charge / discharge, 1 at a temperature of 60 ° C in the charged state
It was stored for 0 days. Then, discharge was performed under the same conditions. Then, the capacity before and after storage was measured.

5th cycle capacity and 20th cycle capacity,
The measurement results of the capacity before and after storage are shown in Table 1 together with the molar fractions of Mn and transition metal in the synthesis of the positive electrode active material.

[0050]

[Table 1]

As can be seen from Table 1, regarding the capacity at the fifth cycle, in the batteries of Examples 1 to 3, Comparative Example 1
It has a capacity equal to or higher than that of the battery.
Regarding the capacity at the 20th cycle, the batteries of Examples 1 to 3 have higher capacities than the battery of Comparative Example 1, and the capacity decrease due to the cycle is suppressed to 1/2 or less. . The storage capacities of the batteries of Examples 1 to 3 are also higher than that of the battery of Comparative Example 1 after storage.

From this, it is found that the lithium manganese oxide prepared by introducing the transition metal is far superior to the pure lithium manganese oxide as the positive electrode active material used in the 4V class battery. It was

Next, the proportion of transition metal introduced into the lithium manganese oxide was examined.

Experimental Example 1 The amount of electrolytic manganese dioxide used was 8.67 g, and the amount of cobalt nitrate dissolved in an aqueous solution was 0.15 g to produce a manganese oxide powder to which cobalt was adhered. A positive electrode active material was synthesized in the same manner as in Example 1 except that 64 g and 1.85 g of lithium carbonate were mixed and heat-treated to prepare a coin-type battery.

Experimental Example 2 The amount of electrolytic manganese dioxide used was 8.66 g, and the amount of cobalt nitrate dissolved in an aqueous solution was 0.30 g to produce a manganese oxide powder to which cobalt was adhered. A positive electrode active material was synthesized in the same manner as in Example 1 except that 57 g and 1.85 g of lithium carbonate were mixed and subjected to heat treatment to prepare a coin-type battery.

Experimental Example 3 The amount of electrolytic manganese dioxide used was 8.27 g, and the amount of cobalt nitrate dissolved in the aqueous solution was 1.45 g to produce a manganese oxide powder to which cobalt was adhered. A positive electrode active material was synthesized in the same manner as in Example 1 except that 72 g and 1.85 g of lithium carbonate were mixed and heat-treated to prepare a coin-type battery.

Experimental Example 4 The amount of electrolytic manganese dioxide used was 7.83 g and the amount of cobalt nitrate dissolved in the aqueous solution was 2.9 g to produce a manganese oxide powder to which cobalt was adhered. A positive electrode active material was synthesized in the same manner as in Example 1 except that 55 g and lithium carbonate 1.85 g were mixed and heat-treated to prepare a coin-type battery.

Experimental Example 5 The amount of electrolytic manganese dioxide used was 6.96 g, and the amount of cobalt nitrate dissolved in an aqueous solution was 5.8 g to produce a manganese oxide powder to which cobalt was adhered. A positive electrode active material was synthesized in the same manner as in Example 1 except that 78 g and 1.85 g of lithium carbonate were mixed and subjected to heat treatment, to produce a coin-type battery.

Experimental Example 6 The amount of electrolytic manganese dioxide used was 6.09 g, and the amount of cobalt nitrate dissolved in an aqueous solution was 8.7 g to produce a powder of manganese oxide to which cobalt was adhered. A positive electrode active material was synthesized in the same manner as in Example 1 except that 82 g and lithium carbonate 1.85 g were mixed and subjected to heat treatment, to produce a coin-type battery.

Experimental Example 7 The amount of electrolytic manganese dioxide used was 6.53 g, and the amount of nickel nitrate hexahydrate dissolved in an aqueous solution was 7.25 g to produce a manganese oxide powder to which nickel was adhered,
Further, a positive electrode active material was synthesized in the same manner as in Example 2 except that 8.41 g of this powder and 1.20 g of lithium carbonate were mixed and heat-treated to prepare a coin-type battery.

Then, the 5th cycle capacity, the 20th cycle capacity, and the capacity before and after storage of the manufactured battery were measured in the same manner as described above. The measurement results are shown in Table 2 together with the mole fractions of Mn and transition metal in the synthesis of the positive electrode active material. Regarding the capacity retention rate (20th cycle capacity / 5th cycle capacity) and capacity retention rate (post-storage capacity / pre-storage capacity) measured with the batteries of Comparative Example 1 and Experimental Examples 1 to 6, The results of plotting the mole fraction on the horizontal axis are also shown in FIG.

[0062]

[Table 2]

In the figure, first, the capacity retention rate gradually increases depending on the mole fraction of Co in the range up to 0.1. Then, when the molar fraction of Co exceeds 0.2, it shows a decreasing change.

On the other hand, the capacity retention rate increases rapidly depending on the molar fraction of Co up to 0.01. And, the molar fraction of Co is 0.01 to 0.2.
The value becomes almost constant in the range of, and gradually decreases thereafter.

From these results, in order to make both the capacity retention rate and the capacity retention rate high, the transition metal such as Co introduced into the lithium manganese oxide has a molar fraction of Mn and the transition metal of 0.99: It can be seen that it is desirable to set so as to be 0.01 to 0.8: 0.2. As Experimental Example 7, a system using Ni as a transition metal was used.
When the mole fraction of was over 0.2, the investigation was carried out, and similarly, the capacity retention rate and the capacity storage rate were low. From this, it is estimated that the range of this mole fraction is also applicable to the case of using other transition metals. In the above, the case where the positive electrode active material was applied to the coin-type battery was described as an example in this example. However, the shape of the battery is not limited to this. It is needless to say that the same effect can be obtained by using the positive electrode active material of the present invention even when applied to a cylindrical battery or a laminated battery.

[0066]

As is apparent from the above description, the positive electrode active material of the present invention has Co, Ni, Fe,
Since it is a spinel type lithium manganese oxide in which Mn is substituted by at least one kind of transition metal selected from V, Cr and Ti, it has a high capacity and is very excellent in stability against voltage. Therefore,
A non-aqueous electrolyte secondary battery using such a lithium manganese oxide as a positive electrode active material can suppress a decrease in cycle capacity to a small extent even when continuously used at a charging voltage of 4 V or more in a high temperature environment, and is excellent. Storage performance is obtained. Furthermore, in this case, even if an expensive transition metal such as Co or Ni is selected as the substitution element, the amount used is extremely small, which is advantageous in reducing the cost of the battery.

[Brief description of drawings]

FIG. 1 is a SEM EMAX of a spinel type lithium manganese oxide in which Mn on the surface is replaced by Co.
It is a characteristic view which shows the spectrum observed by the analysis method.

FIG. 2 is a cross-sectional view showing one structural example of a non-aqueous electrolyte secondary battery to which the present invention is applied.

FIG. 3 is a characteristic diagram showing the relationship between the molar fraction of Co introduced into lithium manganese oxide and the capacity retention rate and capacity retention rate.

[Explanation of symbols] 1 positive electrode 2 negative electrode

Claims (5)

[Claims] 1. On the surface, Co, Ni, Fe, V,
A positive electrode active material, which is a spinel-type lithium manganese oxide in which Mn is substituted with at least one transition metal selected from Cr and Ti. 2. The transition metal with which Mn is substituted is Ni, C.
The positive electrode active material according to claim 1, which is at least one of o and Fe. 3. Manganese dioxide is added to Co, Ni, Fe,
Dispersing in an aqueous solution in which a salt of at least one transition metal selected from V, Cr and Ti is dissolved, adjusting the liquidity to an alkaline side with an aqueous lithium hydroxide solution, and then drying and solidifying this aqueous solution. A method for producing a positive electrode active material, in which a powder in which a transition metal is attached to manganese dioxide is generated in, a powder of lithium carbonate is mixed with the powder, and a heat treatment is performed to synthesize lithium manganese oxide. 4. The molar fraction of Mn and transition metal is 0.9
The method for producing a positive electrode active material according to claim 3, wherein the ratio is 9: 0.01 to 0.8: 0.2. 5. On the surface, Co, Ni, Fe, V,
A non-aqueous electrolyte secondary battery using, as a positive electrode active material, a spinel-type lithium manganese oxide in which Mn is substituted with at least one transition metal selected from Cr and Ti.