JP2001110414A - Material for activating positive electrode of lithium secondary battery and the lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance charging and discharging capacity of a lithium secondary battery during a large-current charging and discharging, where the lithium secondary battery uses a low-price material of iron phosphate lithium as a positive electrode. SOLUTION: A powder 2 is carried on powder 1, where a powder 1 is formed of iron phosphate lithium series material having an olivine structure, which is indicated by the general expression LizFe1-yXyPO4 (0<=y<=0.3, 0<z<=1, X is at least one selected from among magnesium, cobalt, nickel and zinc), while a powder 2 is formed of a material such that it has conductivity and whose oxidation-reduction potential is higher than that of a material for activating a positive electrode of a lithium secondary battery made of iron phosphate lithium series material. Therefore, a battery can be obtained which has larger charging and discharging capacity compared with others using an iron phosphate lithium series material that does not carry powders thereon, where charging and discharging capacity of the battery in relation to the invention is little decreased, even if charging and discharging current increases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive electrode active material for a lithium secondary battery and a lithium secondary battery, and more particularly to an improvement in the conductivity of the positive electrode active material, with the aim of improving the discharge characteristics or charge characteristics of a battery at a large current. Things.

[0002]

2. Description of the Related Art A lithium secondary battery using a lithium metal, a lithium alloy or a material capable of absorbing and releasing lithium ions as a negative electrode active material is characterized by high voltage and excellent reversibility.

In particular, a lithium ion secondary battery using a composite oxide of lithium and a transition metal as a positive electrode active material and a carbon-based material as a negative electrode active material is a conventional lead secondary battery or nickel-cadmium secondary battery. Because of their light weight and large discharge capacity, they are widely used in electronic devices such as mobile phones and notebook personal computers.

[0004] LiCoO ₂ is mainly used as a positive electrode active material of a lithium ion secondary battery generally used at present, but cobalt, which is a raw material of LiCoO ₂ , has a small reserve and is limited in a limited area. As a positive electrode active material for a lithium ion secondary battery, for which further demand is expected to increase in the future, it is not preferable in terms of price and stable supply of raw materials.

On the other hand, LiFePO _4, which uses inexpensive iron as a raw material and has a large amount of output, or a material obtained by substituting part of iron of LiFePO ₄ with another element, operates as a positive electrode active material of a lithium secondary battery. Is disclosed in JP-A-9-134724.
, Japanese Patent Application Laid-Open No. 9-134725, Japanese Patent Application No. 11-2613.
No. 94 and the like.

[0006]

However, these lithium iron phosphate materials have a slow lithium insertion / desorption reaction during charge / discharge of a battery, and the LiCoO ₂ which has been used in the past has been used.
Since the electrical resistance is higher than that of lithium metal oxides, etc., when charging and discharging with a large current, the resistance overvoltage and activation overvoltage increase, and the voltage of the battery decreases. There is a problem that can not be obtained.

As a method for solving such a problem, the particles of the lithium iron phosphate material are made finer to increase the area in which the reaction proceeds, and to shorten the distance that the current flows inside the lithium iron phosphate material particles. It is possible.

However, fine particles of the lithium iron phosphate-based material tend to cause secondary aggregation when mixed with a conductive material at the time of manufacturing an electrode. Since the lithium iron phosphate-based material particles contact each other at small points inside the agglomerates, the electrical resistance becomes extremely large. This does not occur, and the charge / discharge capacity decreases.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a lithium secondary battery using an inexpensive lithium iron phosphate-based material for a positive electrode in a large current charging. It is to increase the charge / discharge capacity at the time of discharge.

[0010]

In order to achieve such an object, a positive electrode active material for a lithium secondary battery according to the present invention comprises:
General formula Li _z Fe _1-y X _y PO ₄ (0 ≦ y ≦ 0.3, 0 <z
≦ 1, X: at least one of magnesium, cobalt, nickel and zinc) on a lithium iron phosphate-based material powder having an olivine structure, which is conductive and has a redox potential of lithium iron phosphate-based material. The present invention is characterized in that a powder of a substance nobler than the oxidation-reduction potential as a positive electrode active material for a secondary battery is supported.

Further, the positive electrode active material for a lithium secondary battery according to the present invention has the above-mentioned conductivity and a redox potential which is more noble than the redox potential as a positive electrode active material for a lithium secondary battery of a lithium iron phosphate-based material. If the substance is silver, carbon, platinum,
Palladium, gold, iridium, aluminum, titanium,
It is characterized by being at least one kind of tantalum.

Further, a lithium secondary battery according to the present invention comprises the above-mentioned positive electrode active material for a lithium secondary battery, further comprises a material capable of occluding and releasing lithium metal, a lithium alloy or lithium ions as a negative electrode active material, It is characterized in that the electrolyte contains, as an electrolyte, a substance in which ions can move to cause an electrochemical reaction with the positive electrode active material and the negative electrode active material.

FIG. 1 is a schematic enlarged cross-sectional view of a part of a positive electrode produced by mixing a positive electrode active material and a conductive material used in a lithium secondary battery according to the present invention. As is clear from this figure, by supporting the conductive fine particles 2 on the surface of the lithium iron phosphate-based material powder 1, there is almost no portion where the lithium iron phosphate-based material powders are in direct contact with each other. Even if the particle diameter of the system material powder 1 is reduced, aggregation when mixed with the conductive material 3 at the time of manufacturing an electrode is less likely to occur.

Further, even when the lithium iron phosphate-based material powder 1 is agglomerated, a current path is formed by the conductive fine particles 2 inside the agglomerated particles. Since the active material inside the agglomerated particles is sufficiently utilized even when charged and discharged with a large current, a decrease in the charge and discharge capacity due to the aggregation of the lithium iron phosphate-based material powder 1 is suppressed.

In the conventional lithium secondary battery positive electrode, the active material particles having a large electric resistance or the active material particles and the conductive material particles are in direct contact with each other, so that a large resistance occurs in a portion having a small contact area. However, in the positive electrode active material of the present invention, since the conductive fine particles 2 are in contact with each other or the conductive fine particles 2 and the conductive material 3, the resistance at the contact surface between the active material and the conductive material 3 is reduced, and Due to the expansion and contraction of the active material when charging and discharging are repeated,
The change in resistance when the contact area changes is also small, the energy loss when charging and discharging with a large current is reduced, and the capacity deterioration due to charging and discharging is also reduced. By combining these effects, the use of the positive electrode active material of the present invention increases the charge / discharge capacity of a lithium secondary battery using a lithium iron phosphate-based material as the positive electrode active material at the time of large current charge / discharge. It is thought that.

The lithium iron phosphate-based material of the positive electrode active material of the lithium secondary battery according to the present invention has a general formula Li _z Fe _1-y X _y
A phosphate compound having an olivine structure given by PO ₄ (0 <z ≦ 1, 0 <y ≦ 0.3). In a state where the phosphate compound is formed, the element X is based on the standard potential of lithium metal. It is an electrochemically stable substance in the potential range of 3 V to 4 V. That is, X is at least one of magnesium, cobalt, nickel, and zinc. FIG.
2 shows the olivine structure of PO ₄ . Black circles represent lithium atoms,
The octahedron indicates iron surrounded by six oxygen atoms, and the tetrahedron indicates phosphorus surrounded by four oxygen atoms.

The above-mentioned substance generally called lithium iron phosphate is represented by LiFePO ₄ (z = 1, y = 0), and lithium cannot be inserted any more while maintaining the structure. . When this lithium iron phosphate-based material is used as the positive electrode of a battery, when the battery is charged, lithium escapes from the positive electrode, the composition approaches FePO ₄ (z becomes small), and when the charged battery is discharged, the electrolytic solution The lithium therein is inserted into the positive electrode, and the composition is LiFePO ₄ (z =
Go back to 1). Considering the discharge capacity and fabrication of the battery, z
= 1 is most preferable, but since the value of z changes continuously in this way, even a substance having a non-stoichiometric composition such as z = 0.9 has a general constant-stoichiometric composition. A battery that operates by a mechanism equivalent to lithium iron phosphate with z = 1 can be manufactured. Therefore, in the above formula, z is represented by 0 <z ≦ 1.

In LiFePO ₄ , lithium is desorbed during charging, and iron ions change from divalent to trivalent. As a result of the elimination of lithium, the crystal structure (olivine structure) at that portion becomes unstable, and the movement path of lithium is partially blocked, and further, the lithium inside becomes difficult to be eliminated. When a part of iron is replaced by an element such as zinc which is electrochemically stable in a potential region of 3 V to 4 V with respect to the standard potential of lithium metal in a state where the phosphate compound is formed, the zinc is charged even if charging is performed. The substituted element such as is not oxidized as it is divalent, and lithium adjacent to the substituted element remains in the crystal without being eliminated. For this reason, it is considered that the crystal structure of the replaced portion is unlikely to change even after charging, and the lithium migration path is secured, thereby increasing the capacity and improving the cycle stability. However, lithium that does not desorb does not participate in charge and discharge, so that if such replacement is performed too much, the capacity of the battery will decrease. For this reason, when replacing the iron element, the replacement amount of the iron element, which has the effect of increasing the capacity, is 30% (0 ≦ y ≦ 0.3).
Hereinafter, preferably 10% to 30% (0.1 ≦ y ≦ 0.3
), More preferably 10 to 20% (0.1 ≦ y ≦
0.2).

In the present invention, the surface of the lithium iron phosphate-based material is electrically conductive and the oxidation-reduction potential is more noble than the oxidation-reduction potential of the lithium iron phosphate-based material as a positive electrode active material for a lithium secondary battery. (High) conductive fine particles are adhered. This is because when the potential at which the electrochemical reaction of the conductive fine particles occurs in the lithium secondary electrons is lower than the oxidation-reduction potential (about 3.4 V) of the lithium iron phosphate-based material, the conductive fine particles first perform the electrochemical reaction. This is because of the occurrence of dissolution or reduction in conductivity due to oxidation, and the effect of supporting the conductive fine particles is lost.

Such conductive fine particles are preferably at least one of silver, carbon, platinum, palladium, gold, iridium, aluminum, titanium and tantalum, for example. In the examples described below, silver, palladium, and platinum were used as the metal material as the conductive fine particles, and acetylene black was used as the carbon material.In addition, as the metal material, gold, iridium, aluminum, titanium, Tantalum may be used. In addition, graphite or Ketjen black may be used as the carbon material.

Further, as the amount of the conductive fine particles added, since this substance itself does not participate in the charge / discharge reaction, if the added amount is excessively increased, the entire positive electrode active material including the lithium iron phosphate-based material and the conductive fine particles is added. Since the discharge capacity per unit weight or unit volume is reduced, 10% or less is preferable, and 2% to 6% is particularly preferable.

The particle size of the conductive fine particles is preferably 1/10 or less, more preferably 1/100 or more and 1/10 or less of the particle size of the lithium iron phosphate-based material powder. Since the conductive fine particles do not participate in the battery reaction, it is preferable that the conductive fine particles be evenly attached to the surface of the lithium iron phosphate-based material powder with as little weight as possible. For this reason, when the particle size of the conductive particles is large, evenly adhered to the surface of the lithium iron phosphate-based material powder, the amount of the conductive particles becomes too large, which may cause a decrease in energy density. is there.

Further, in Examples described later, a positive electrode molded in a pellet shape was used.
The slurry may be prepared by adding a positive electrode active material and a binder such as polyvinylidene fluoride to a solvent such as 21-pyrrolidone, and the slurry may be thinly coated on a metal foil and dried to form a coated electrode.

Although lithium metal was used as the negative electrode material, other materials such as lithium alloys, carbon-based materials such as graphite and coke, and metal oxides such as tungsten oxide, niobium oxide, vanadium oxide, and tin oxide were also used. Alternatively, lithium transition metal composite nitrides such as lithium manganese nitride, lithium cobalt nitride, and lithium iron nitride, and metal chalcogenites such as iron sulfide and molybdenum sulfide may be used.

As an electrolytic solution, LiPF ₆ is used in a mixed solvent of equal volume of ethylene carbonate and dimethyl carbonate.
Was dissolved in a concentration of 1 mol / dm ³ ,
A battery similar to a conventional non-aqueous lithium secondary battery can also be used.

For example, dimethoxyethane, 2
-Methyltetrahydrofuran, ethylene carbonate,
Methyl formate, dimethyl sulfoxide, propylene carbonate, acetonitrile, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and the like can be used alone or in combination of two or more.

As the solute, other than LiPF ₆ used in Examples, for example, LiClO ₄ , LiB
P ₄ , LiAsF ₆ , LiCF ₃ SO ₃ or the like may be used. Further, a polymer electrolyte, a solid electrolyte, a room temperature molten salt and the like can be used.

As for other elements such as a structural material such as a separator and a battery case, various conventionally known materials can be used. Further, the shape of the battery is also a coin type in the embodiment, but is not particularly limited, and may be a cylindrical shape, a square shape, or the like.

[0029]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present invention is not limited only to the following examples.

[0030]

Embodiment 1 FIG. 3 is a sectional view showing a structure of a lithium secondary battery according to an embodiment of the present invention. In FIG. 3, 4 is a positive electrode pellet, 5 is a metal lithium negative electrode, 6 is a separator, 7 is a positive electrode case, 8 is a sealing plate, and 9 is a gasket. The positive electrode active material contained in the positive electrode pellet 4 was produced by the following method.

First, lithium carbonate (Li ₂ CO ₃ ) which is a raw material of LiFePO ₄ and iron oxalate dihydrate (FeC ₂
O ₄ · 2H and ₂ O), diammonium hydrogen phosphate ((NH
₄ ) ₂ HPO ₄ ) is mixed in a molar ratio of 0.5: 1: 1, put into a crucible, and heated at 800 ° C. in an argon atmosphere.
It was synthesized by firing for 4 hours.

Then, water and ethanol were mixed at a volume ratio of 1: 1.
The synthesized LiFePO ₄ powder is placed in the solution mixed with the above, and the mixture is sufficiently stirred, and while stirring is continued, silver nitrate (AgNO ₃ )
Was weighed so that the weight of silver ions contained therein was 5% of the weight of LiFePO ₄ .

While continuing stirring, acetaldehyde was added to LiFeP by adding 20 ml per 1 g of AgNO _3.
Silver was deposited on the O ₄ powder. This was filtered and dried to produce a positive electrode active material.

FIG. 4 shows an X-ray diffraction chart of the obtained positive electrode active material. In addition to the LiFePO ₄ peak, a silver peak in a metal state indicated by * in FIG. 4 was observed. The electron microscopic observation and EPMA measurement, silver fine particle size of about 1/20 of the particle size of LiFePO ₄ powder LiFePO ₄ on powder was confirmed that they are dispersed and carried.

[0035] 70% by weight of this positive electrode active material, 25% by weight of acetylene black as a conductive material and 5% by weight of polytetrafluoroethylene as a binder were kneaded to obtain a clay-like mass, which was then thickened with a biaxial roller. After being rolled to a thickness of about 0.6 mm, a positive electrode pellet 4 was prepared by punching out a disk having a diameter of 15 mm with a punch.

Next, a metal lithium negative electrode 5 placed under pressure on a stainless steel sealing plate 8 is inserted into the concave portion of the polypropylene gasket 9, and a polypropylene microporous separator is placed on the negative electrode. The pellets 4 are arranged in this order, and 1 mol of LiPF ₆ is used as an electrolytic solution in an equal volume mixed solvent of ethylene carbonate and dimethyl carbonate.
After injecting and impregnating an appropriate amount of an electrolytic solution dissolved in a concentration of l / dm ³ , a stainless-steel positive electrode case 7 is covered and swaged to produce a coin-type lithium secondary battery having a thickness of 2 mm and a diameter of 23 mm. did.

The charge / discharge characteristics of the produced battery were evaluated by charging / discharging under the conditions of a charge end voltage of 4.0 V, a discharge end voltage of 3.0 V, 1 mA, and a constant current of 5 mA, which is a large current.

FIG. 5 shows a voltage curve when discharging at a current of 5 mA. The voltage curve is almost the same as the voltage when charging and discharging a battery using lithium iron phosphate not supporting already known conductive fine particles as a positive electrode and lithium metal as a negative electrode with a small current, Charge / discharge was performed by oxidation / reduction of iron ions, and it was confirmed that oxidation / reduction of the carried conductive material did not occur.

The discharge capacity is 5.6 m when the current is 1 mA.
Ah, when the current was 5 mA, it was 4.3 mAh. Table 1 shows the discharge capacity when the charge / discharge test was performed at each current value.
Shown in

[0040]

[Table 1]

[0041]

Comparative Example 1 LiFePO ₄ , which is a positive electrode active material which was not subjected to a conductive material supporting treatment, was prepared by the following method.

First, the raw material lithium carbonate (Li)_TwoC
O_Three) And iron oxalate dihydrate (FeC _TwoO_Four・ 2H_TwoO)
And diammonium hydrogen phosphate ((NH_Four)_TwoHPO_Four)
Into a crucible in a molar ratio of 0.5: 1: 1
And baked at 800 ° C for 24 hours under argon atmosphere
In this way, it was produced.

Using the obtained positive electrode active material, a positive electrode pellet and a coin-type battery were produced in the same manner as in Example 1.

When the charge and discharge characteristics were evaluated under the same conditions as in Example 1, the discharge capacity was 5.2 m when the current was 1 mA.
In the case of Ah and a current of 5 mA, 3.6 mAh was obtained. In each case, a smaller discharge capacity than that of Example 1 was obtained. In particular, when the test was performed at a constant current of 5 mA, the capacity was significantly reduced.

FIG. 4 shows a voltage curve when discharging at a current of 5 mA together with the curve of Example 1. Table 1 shows the discharge capacity when the charge / discharge test was performed at each current value together with the value of Example 1.

[0046]

Example 2 A positive electrode active material contained in a positive electrode pellet was prepared by the following method.

First, lithium carbonate (Li) as a raw material is used._TwoC
O_Three) And iron oxalate dihydrate (FeC _TwoO_Four・ 2H_TwoO)
And diammonium hydrogen phosphate ((NH_Four)_TwoHPO_Four)
Into a crucible in a molar ratio of 0.5: 1: 1
And baked at 350 ° C. for 5 hours in an argon atmosphere.

Then, 10 g of acetylene black (manufactured by Denki Kagaku Kogyo) was added per 1 kg of the raw material, mixed well, and fired at 800 ° C. for 24 hours in an argon atmosphere.

Using the obtained positive electrode active material, a positive electrode pellet and a coin-type battery were produced in the same manner as in Example 1.

When the charge and discharge characteristics were evaluated under the same conditions as in Example 1, the discharge capacity was 5.7 m when the current was 1 mA.
In the case of Ah and the current of 5 mA, it was 4.4 mAh. In each case, a larger discharge capacity than that of Comparative Example 1 was obtained.

Table 1 shows the discharge capacity when the charge / discharge test was performed at each current value, together with the values of Example 1 and Comparative Example 1.

[0052]

Example 3 A positive electrode active material contained in a positive electrode pellet was prepared by the following method.

First, lithium carbonate (Li ₂ CO ₃ ), which is a raw material of LiFePO ₄ , and iron oxalate dihydrate (FeC ₂
O ₄ · 2H ₂ O) and diammonium hydrogenphosphate ((N
H ₄ ) ₂ HPO ₄ ) was mixed in a molar ratio of 0.5: 1: 1, put in a crucible, and baked at 800 ° C. for 24 hours in an argon atmosphere.

Next, palladium acetate (Pd (OCOC)
LiFeP synthesized in acetonitrile solution of H ₃ ) ₂ )
After O ₄ was pulverized and added, the mixture was sufficiently stirred, filtered, dried, and Pd (OCOCH ₃ ) ₂ was adhered on the LiFePO ₄ powder.

This was calcined at 250 ° C. for 5 hours in an argon atmosphere, and Pd (OCOCH ₃ ) ₂ was thermally decomposed to obtain Ld.
A positive electrode active material was prepared by supporting palladium on iFePO ₄ powder.

Using the obtained positive electrode active material, a coin battery was manufactured in the same manner as in Example 1.

When the charge and discharge characteristics were evaluated under the same conditions as in Example 1, the discharge capacity was 5.4 m when the current was 1 mA.
In the case of Ah and the current of 5 mA, it was 4.0 mAh. In each case, a larger discharge capacity than that of Comparative Example 1 was obtained.

Table 1 shows the discharge capacity when the charge / discharge test was performed at each current value, together with the values of Examples 1 and 2 and Comparative Example 1.

[0059]

Example 4 A positive electrode active material contained in a positive electrode pellet was produced by the following method.

First, lithium hydroxide monohydrate (LiOH.H ₂ O) as a raw material and iron oxalate dihydrate (FeC ₂
O ₄ · 2H and ₂ O), diammonium hydrogen phosphate ((NH
₄ ) ₂ HPO ₄ ) was mixed at a molar ratio of 1: 1: 1, put in a crucible, and fired at 800 ° C. for 24 hours in an argon atmosphere to synthesize LiFePO ₄ .

Next, L was added to the obtained LiFePO ₄ powder.
6 g of platinum powder (300 g per 100 g of iFePO ₄₎
The resulting mixture was mixed in a mortar, placed in a planetary ball mill made of agate, crushed and mixed for 20 minutes, and platinum fine particles were dispersed and supported on the LiFePO ₄ powder.

Using the obtained positive electrode active material, a coin battery was manufactured in the same manner as in Example 1.

When the charge and discharge characteristics were evaluated under the same conditions as in Example 1, the discharge capacity was 5.5 m when the current was 1 mA.
Ah, when the current was 5 mA, it was 4.1 mAh. Table 1 shows the discharge capacity when the charge / discharge test was performed at each current value, together with the values of Examples 1 to 3 and Comparative Example 1.

[0064]

As described above, according to the lithium secondary battery of the present invention, by using a material in which conductive fine particles are supported on a lithium iron phosphate-based material powder as a positive electrode active material, It has been found that a battery having a larger charge / discharge capacity and a smaller decrease in the charge / discharge capacity even when the charge / discharge current is increased can be obtained, as compared with a battery using a lithium iron phosphate-based material that is not supported.

Accordingly, it has become possible to realize a lithium secondary battery which is economically excellent and has good battery characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view in which a part of a positive electrode manufactured by mixing a lithium secondary battery positive electrode active material and a conductive material according to the present invention is enlarged.

FIG. 2 is a schematic view showing an olivine structure.

FIG. 3 is a cross-sectional view showing a configuration of an embodiment of a lithium secondary battery according to the present invention.

FIG. 4 is a diagram illustrating an example of a lithium secondary battery according to a first embodiment of the present invention.
shows the X-ray diffraction pattern of LiFePO _4.

FIG. 5 is a diagram showing discharge curves of the lithium secondary battery of Example 1 and Comparative Example 1 of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 lithium iron phosphate-based material powder 2 conductive fine particles 3 conductive material 4 positive electrode pellet 5 metallic lithium negative electrode 6 separator 7 positive electrode case 8 sealing plate 9 gasket

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Takei, Inventor 2-3-1 Otemachi, Chiyoda-ku, Tokyo Within Nippon Telegraph and Telephone Corporation (72) Yoji Sakurai 2-chome, Otemachi 2-chome, Chiyoda-ku, Tokyo No. 1 F-term in Nippon Telegraph and Telephone Corporation (reference)

Claims (3)

[Claims] 1. A method according to claim 1, wherein Li _z Fe _1-y X _y PO ₄ (0 ≦ y ≦
0.3, 0 <z ≦ 1, X: at least one of magnesium, cobalt, nickel, and zinc) on a lithium iron phosphate-based material powder having an olivine structure,
A positive electrode active material for a lithium secondary battery, wherein the positive electrode active material carries conductive fine particles having a redox potential higher than the redox potential of a lithium iron phosphate-based material as a positive electrode active material for a lithium secondary battery. 2. The method according to claim 1, wherein the conductive fine particles are silver, carbon, platinum,
Palladium, gold, iridium, aluminum, titanium,
The lithium secondary battery positive electrode active material according to claim 1, wherein the positive electrode active material is at least one kind of tantalum. 3. The lithium secondary battery positive electrode active material according to claim 1 or 2 as a positive electrode active material, a lithium metal, a lithium alloy or a material capable of occluding and releasing lithium ions as a negative electrode active material. Contains, as an electrolyte, a substance which can move to perform an electrochemical reaction with the positive electrode active material or the negative electrode active material of the lithium secondary battery.