JP2001068153A - Lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove or fix the moisture and HF in an electrolyte that exert a harmful influence on cycle characteristics of a battery so as to suppress decomposition of the electrolyte and obstruction of battery reaction by adding a water extraction agent to a nonaqueous electrolyte containing a lithium compound as an electrolyte salt. SOLUTION: The water extraction agent is a material dissolving in a nonaqueous electrolyte, an organic phosphorus compound is listed, and the phosphorous compound having P=0 bonding, especially a phosphate or a phosphine oxide is preferable. A hydrofluoric acid extraction agent is added to the nonaqueous electrolyte containing the lithium compound as the electrolyte, the hydrofluoric acid extraction agent is preferable to be an organic silicone compound or an organic antimony compound, especially the compound dissolving in the nonaqueous electrolyte. As the preferable organic silicone compound, silanes are listed. Simultaneous addition of the water extraction agent and the hydrofluoric acid extraction agent to the electrolyte is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery which has excellent cycle characteristics and reliability and is easy to manufacture.

[0002]

2. Description of the Related Art In recent years, lithium secondary batteries have been widely used as small, chargeable / dischargeable secondary batteries having a large energy density and serving as power supplies for electronic devices such as portable communication devices and notebook personal computers. It is becoming. Also, with the growing interest in resource and energy savings against the backdrop of international protection of the global environment, lithium secondary batteries are being used in motor vehicles for electric vehicles, which are being considered for active market introduction in the automotive industry. It is also expected to be a battery or a means for effectively using electric power by storing nighttime electric power, and there is an urgent need for a large-capacity lithium secondary battery suitable for these uses.

In a lithium secondary battery, generally, a lithium transition metal composite oxide or the like is used as a positive electrode active material, and a carbonaceous material such as hard carbon or graphite is used as a negative electrode active material. Since the reaction potential of a lithium secondary battery is as high as about 4.1 V, a conventional aqueous electrolyte cannot be used as an electrolyte, and therefore, a lithium ion (Li ⁺ ) electrolyte is dissolved in an organic solvent. The used non-aqueous electrolyte is used. The charging reaction occurs when Li ^{+ in} the positive electrode active material moves to the negative electrode active material through the nonaqueous electrolyte and is captured, and the opposite battery reaction occurs during discharging.

[0004]

Here, the non-aqueous electrolyte usually contains a small amount of moisture as a contaminant from the manufacturing stage. In addition, various materials and components (such as a positive electrode active material, a metal terminal, and a battery case) constituting a battery are generally stored in a normal atmospheric atmosphere, and thus are adsorbed on the surfaces of the components. Moisture may enter the non-aqueous electrolyte when the battery is completed.

[0005] When such moisture is present in the non-aqueous electrolyte, the electrolyte is decomposed by the moisture, and when an acidic substance or the like is generated, there is a problem that the battery life is shortened. For example, lithium hexafluorophosphate (LiPF ₆ ) has attracted the most attention as an electrolyte because it dissolves in an organic solvent and exhibits high conductivity, but when LiPF ₆ is used,
If water is present in the solvent, hydrofluoric acid (HF) is generated, and this HF dissolves metal materials such as battery containers and current collectors.
It causes problems such as corrosion and inhibition of the function of Li ⁺ , which causes battery deterioration. Such deterioration of the battery characteristics appears remarkably in a cycle operation in which charge and discharge are repeated, and is a fatal defect as a secondary battery.

Therefore, as a method for removing water in a non-aqueous electrolyte, Japanese Patent Application Laid-Open No. 9-139232 discloses a method in which a non-aqueous electrolyte contains a boron compound or zeolite. The publications disclose methods of adding an acid anhydride such as acetic anhydride to a non-aqueous electrolyte.

However, the method of adding a boron compound to a non-aqueous electrolyte is based on a method in which LiPF ₆ reacts with water in the non-aqueous electrolyte to form HF, which further reacts with a metal container or the like to produce fluorine ions (F ^−). ) Is reacted with a boron compound and immobilized, so that it is a countermeasure method after corrosion of a metal container or the like has occurred as a result.

As a large-capacity lithium secondary battery used for electric vehicles and the like, for example, a positive / negative electrode plate in which an electrode active material is coated on both surfaces of a metal foil having a length of several meters and a width of several tens cm is used. After the internal electrode body tightly wound via a separator is housed in a battery case, a nonaqueous electrolyte can be used to impregnate the internal electrode body. In this case, a solid such as zeolite can be used. There is a problem that the powder is hardly impregnated inside the internal electrode body.

That is, although zeolite is sufficiently effective to be used for the water removal treatment of the nonaqueous electrolyte before filling the battery, there is a question about the water removal effect when it is present in the battery. . Furthermore, even if solid powder can be impregnated into the internal electrode body, it partially clogs the separator,
The battery reaction may be hindered.

On the other hand, when an acid anhydride is used, water can be removed by hydration of the acid anhydride. However, when a large current is discharged and the battery temperature rises, Since a water elimination reaction easily occurs and water is dissolved into the non-aqueous electrolyte again, it is not always a sufficient method from the viewpoint of long-term reliability.

[0011] Even when a water removing agent is added to the non-aqueous electrolyte, it is expected that it is difficult to completely remove water. Therefore, generation of HF is considered unavoidable, and it is considered preferable to add a component that removes HF in addition to the water removing agent to prevent corrosion of the metal material due to HF. Further, it is considered that by adding an HF remover instead of the water remover, it is possible to suppress the metal corrosion caused by HF and the disturbance of the battery reaction.

[0012]

Means for Solving the Problems The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to solve the problem of water and electrolyte in an electrolytic solution which greatly affect the cycle characteristics of a battery. By removing or fixing HF, decomposition of the electrolyte and inhibition of the battery reaction are suppressed,
An object of the present invention is to provide a highly reliable lithium secondary battery.

That is, according to the present invention, there is provided a lithium secondary battery using a non-aqueous electrolyte containing a lithium compound as an electrolyte, wherein a water extractant is added to the non-aqueous electrolyte. Lithium secondary battery is provided.

As the water extractant, one that dissolves in a non-aqueous electrolyte is suitably used, and specific examples include an organic phosphorus compound. The organic phosphorus compound preferably has a P = 0 bond, and is more preferably a phosphate or phosphine oxide.

Further, according to the present invention, there is provided a lithium secondary battery using a non-aqueous electrolyte containing a lithium compound as an electrolyte, wherein a hydrofluoric acid extractant is added to the non-aqueous electrolyte. A lithium secondary battery is provided.

Here, as the hydrofluoric acid extractant, an organic silicon compound or an organic antimony compound is suitably used, and it is particularly preferable to use a compound which dissolves in a non-aqueous electrolyte. Those preferably used as the organic silicon compound are silanes. It is also preferable to simultaneously add a water extractant and a hydrofluoric acid extractant to the electrolytic solution.

The electrode active material used in the above-described lithium secondary battery of the present invention is not particularly limited, and lithium manganate having a cubic spinel structure containing lithium and manganese as main components is used as a positive electrode active material. In this case, the internal resistance of the battery can be reduced, and in this case, the cycle characteristics are improved by the synergistic effect of suppressing the deterioration of the non-aqueous electrolyte, which is preferable. The lithium secondary battery of the present invention is suitably used for a large battery having a battery capacity of 2 Ah or more, and is also suitably used as a power source for driving a motor of an electric vehicle or a hybrid electric vehicle in which a large current is frequently discharged. Can be

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The lithium secondary battery of the present invention
A non-aqueous electrolyte containing a lithium compound as an electrolyte is used, and the cycle characteristics are improved by suppressing the deterioration of the non-aqueous electrolyte. Therefore,
There are no restrictions on other materials or battery structures. Hereinafter, first, the main members constituting the battery and the structure thereof will be outlined.

One structure of an internal electrode body, which can be said to be the heart of a lithium secondary battery, has a structure in which positive and negative electrode active materials are press-formed into a disk shape and a separator is sandwiched between them, as seen in a small-capacity coin battery. It has a single cell structure.

One structure of an internal electrode body used for a battery having a large capacity is a wound type as compared with a small-capacity battery such as a coin battery. As shown in the perspective view of FIG.
The wound-type internal electrode body 1 has a positive electrode plate 2 and a negative electrode plate 3 on an outer periphery of a core 13 so that the positive electrode plate 2 and the negative electrode plate 3 are not directly in contact with each other via a separator 4 made of a porous polymer. It is configured by winding. Electrode lead 5 attached to positive electrode plate 2 and negative electrode plate 3 (hereinafter referred to as “electrode plates 2 and 3”)
It is sufficient that the number of 6 is at least one, and a plurality of electrode leads 5
6, the current collecting resistance can be easily reduced.

As another structure of the internal electrode body, there is a laminated type in which a single-cell type internal electrode body used for a coin battery is laminated in a plurality of stages. As shown in FIG. 2, the laminated internal electrode body 7 is obtained by alternately laminating a positive electrode plate 8 and a negative electrode plate 9 of a predetermined shape with a separator 10 interposed therebetween.
At least one electrode lead 11
12 is attached. The materials used and the manufacturing method of the electrode plates 8 and 9 are described in detail below.
Same as 3 and so on.

Next, the configuration of the wound internal electrode body 1 will be described in more detail by way of example. The positive electrode plate 2 is manufactured by applying a positive electrode active material to both surfaces of a current collecting substrate. As the current collecting substrate, a metal foil having good corrosion resistance to a positive electrode electrochemical reaction such as an aluminum foil or a titanium foil is used, but a punching metal or a mesh (net) can be used instead of the foil. As the positive electrode active material, lithium manganate (LiMn ₂ O ₄ ), lithium cobaltate (LiCoO ₂ ), lithium nickelate (L
A lithium transition metal composite oxide such as iNiO ₂ ) is suitably used, and preferably, a fine carbon powder such as acetylene black is added as a conductive additive to these.

Here, in particular, when lithium manganate having a cubic spinel structure (hereinafter, referred to as “LiMn ₂ O ₄ spinel”) is used, the inside of the electrode becomes more in comparison with the case where another electrode active material is used. This is preferable because the resistance of the electrode body can be reduced. The effect of improving the characteristics of the non-aqueous electrolyte in the present invention, which will be described later, is more remarkable when combined with the effect of reducing the internal resistance, and the cycle characteristics of the battery are improved.

It should be noted that the LiMn ₂ O ₄ spinel is not limited to such a stoichiometric composition.
general formula LiM wherein n is partially substituted with one or more other elements
Spinel represented by _X Mn _2-X O ₄ (M represents a substitution element and X represents a substitution amount) is also suitably used. The substitution elements M are listed below by element symbols.
n, Ni, Mg, Zn, B, Al, Co, Cr, Si,
Ti, Sn, P, V, Sb, Nb, Ta, Mo, W.

Here, regarding the substitution element M, Li is theoretically +1, and Fe, Mn, Ni, Mg, and Zn are +
Divalent, B, Al, Co, Cr are trivalent, Si, Ti, S
n is +4, P, V, Sb, Nb and Ta are +5, M
o and W are +6 valent ions and are elements that form a solid solution in LiMn ₂ O _4. Co and Sn are +2 valent, and Fe, Sb and Ti are +3 valent.
For +3 and +4, for Cr +4
Valence, +6 valence.

Therefore, the various substitution elements M may exist in a state having a mixed valence, and the amount of oxygen needs to be 4 as represented by the stoichiometric composition. However, it may be deficient or excessive in the range for maintaining the crystal structure.

The coating of the positive electrode active material is performed by applying a slurry or paste prepared by adding a solvent, a binder, or the like to the positive electrode active material powder to a current collecting substrate by using a roll coater method or the like and drying it. After that, a pressing process or the like is performed as necessary.

The negative electrode plate 3 can be manufactured in the same manner as the positive electrode plate 2. As the current collecting substrate of the negative electrode plate 3, a metal foil having good corrosion resistance to a negative electrode electrochemical reaction such as a copper foil or a nickel foil is suitably used. As the negative electrode active material, an amorphous carbonaceous material such as soft carbon or hard carbon, or a highly graphitized carbonaceous powder such as artificial graphite or natural graphite is used.

The separator 4 preferably has a three-layer structure in which a Li ⁺ permeable polyethylene film (PE film) having micropores is sandwiched between porous Li ⁺ permeable polypropylene films (PP films). Used for This also serves as a safety mechanism for suppressing the movement of Li ⁺ , that is, the battery reaction, when the temperature of the internal electrode body rises, the PE film softens at about 130 ° C. and the micropores are crushed. By sandwiching the PE film between PP films having a higher softening temperature, even when the PE film is softened, the PP film retains its shape and prevents contact and short circuit between the positive electrode plate 2 and the negative electrode plate 3. In addition, it is possible to reliably suppress the battery reaction and ensure the safety.

During the winding work of the electrode plates 2 and 3 and the separator 4, the electrode leads 5 and 6 are provided on the portions of the electrode plates 2 and 3 where the current collecting substrate not coated with the electrode active material is exposed.
Are respectively attached. As the electrode leads 5 and 6, foil-like ones made of the same material as the current collecting substrate of each of the electrode plates 2 and 3 are preferably used. Electrode leads 5 and 6
Can be attached to the electrode plates 2 and 3 using ultrasonic welding, spot welding, or the like. At this time, as shown in FIG. 1, when the electrode leads 5 and 6 are respectively attached so that the electrode leads of one electrode are arranged on one end surface of the internal electrode body 1, the contact between the electrode leads 5 and 6 is reduced. It can be prevented and is preferred.

In assembling the battery, first, the internal electrode body 1 manufactured is inserted into the battery case while ensuring conduction between the terminal for extracting a current to the outside and the electrode leads 5 and 6, thereby ensuring a stable operation. Hold in position. Then, after impregnating with a non-aqueous electrolyte, the battery case is sealed to produce a battery.

Next, the non-aqueous electrolyte used in the lithium secondary battery of the present invention will be described. Examples of the solvent include carbonates such as ethylene carbonate (EC), diethyl carbonate (DEC) and dimethyl carbonate (DMC), propylene carbonate (PC), γ-butyrolactone, tetrahydrofuran,
A single solvent such as acetonitrile or a mixed solvent is suitably used.

As a lithium compound dissolved in such a solvent, that is, as an electrolyte, a lithium complex fluorine compound such as lithium hexafluorophosphate (LiPF ₆ ) or lithium borofluoride (LiBF ₄ ), or lithium perchlorate ( LiClO ₄ ) and the like, and one or more of them may be used by dissolving them in the solvent. In particular, it is preferable to use LiPF ₆ which does not easily undergo oxidative decomposition and has high conductivity of the non-aqueous electrolyte.

In preparing such a non-aqueous electrolyte, strict water management is performed in the production and storage stages of the solvent and the electrolyte, but mixing of a trace amount of water is inevitable. Also, considering the battery assembling process, parts other than the non-aqueous electrolyte are usually stored in the air, so that there is a very high possibility that a small amount of water is adsorbed on the surface thereof. Is not easily removable even if drying or other processing is performed before or during battery assembly.

Therefore, in the present invention, as the electrolyte to be filled in the battery, a general non-aqueous electrolyte obtained by dissolving the above-mentioned electrolyte in a predetermined organic solvent, and further adding a water extractant are used. Used. By adding the water extractant, it is possible to reduce the water concentration in the non-aqueous electrolyte before injecting into the battery, and, after injecting into the battery, to remove the water adsorbed on the electrode plate or the like. Removal will be easy. Thus, decomposition of the electrolyte is suppressed, and the cycle characteristics are improved.

The water extractant in the present invention refers to JP-A-9-139232 and JP-A-7-122 cited above.
No. 297, which is a concept that does not include a water removing agent, which is dissolved in an organic solvent and has high activity and free water molecules existing in the organic solvent, and a (water extractant) _a · (H ₂ O) It reacts in the form of _b and has the property of reducing the activity of water.

As such a water extractant, it is preferable to use a liquid extract that is uniformly mixed with the electrolytic solution and is uniformly impregnated in the internal electrode body. Specific examples of the water extractant that can be used in the present invention include organic phosphorus compounds and amine compounds. When an organic phosphorus compound is used, it is preferable that the compound has a bond of P = 0. If the compound name is mentioned, trimethyl phosphate, tri-2-propyl phosphate, tributyl phosphate, tetraisopropyl ethylene phosphate And phosphine oxides such as tributyl phosphine oxide, trioctyl phosphine oxide, and triphenyl phosphine oxide.

Here, the reaction of water extraction in the case of using trimethyl phosphate is represented by the following chemical formula 1.

[0039]

Embedded image a (CH ₃ O) ₃ PO + bH ₂ O → ((CH ₃ O) ₃
PO) _a・ (H ₂ O) _b

By the way, it is expected that it is difficult to completely remove water even when the extractant is added to the non-aqueous electrolyte as described above. Therefore, it is considered preferable to add a hydrofluoric acid extractant that directly removes HF in addition to the water extractant to prevent corrosion of the metal material due to HF. Further, the hydrofluoric acid extractant can be added to the non-aqueous electrolyte alone in place of the water extractant to obtain H
It is considered that this contributes to suppression of metal corrosion and the like due to F and improves cycle characteristics.

From such a viewpoint, in the present invention, it is also preferable to add a hydrofluoric acid extractant to the non-aqueous electrolyte. Hydrofluoric acid extractant can be used in combination with the water extractant, as shown in the test results described below,
It was confirmed that even when used alone, it greatly contributes to the improvement of the cycle characteristics as in the case where the water extractant was used alone.

As the hydrofluoric acid extractant, an organic silicon compound or an organic antimony compound is preferably used.
As with the water extractant, it is preferable to use a liquid material.
Examples of the organic silicon compound include silanes and polysiloxane, and particularly preferably used compounds are triethylsilane, triphenylsilane, methyltriethoxysilane, ethyl silicate, methyltriacetoxysilane, ethyltrichlorosilane, and iodo. Silanes such as trimethylsilane. As organic antimony compounds,
Tetraphenylantimony ion can be mentioned.

Here, the reaction of hydrofluoric acid extraction using triethylsilane is represented by the following chemical formula 2.

[0044]

(C ₂ H ₅ ) ₃ SiH + HF → (C ₂ H ₅ ) ₃ SiF +
H ₂

The hydrofluoric acid extractant in the present invention is:
As shown in the above formula 2, HF itself is not fixed, but forms a compound with fluorine ions. When silanes are used, hydrogen gas is generated, but the amount of hydrogen gas generated is very small, does not cause a large change in the internal pressure of the battery, and does not adversely affect the battery characteristics.

FIG. 3 is a graph showing cycle characteristics of batteries manufactured using various non-aqueous electrolytes shown in Table 1. LiPF ₆ is used as the electrolyte, and an equal amount (equal volume) mixed solvent of EC and DEC is used as the organic solvent, and these are common to all the samples. As shown in Table 1, in Example 1, triethylsilane was added as a water extractant, in Example 2, tributyl phosphate was added as a hydrofluoric acid extractant, and in Example 3, triethylsilane and tributyl phosphate were added. However, in the comparative example, neither the water extractant nor the hydrofluoric acid extractant was added.

[0047]

[Table 1]

The batteries according to Examples 1 to 3 and Comparative Example were obtained by adding LiMn ₂ O ₄ spinel as a positive electrode active material, and adding acetylene black as a conductive additive to the same at an external ratio of about 4% by weight. Further, a positive electrode material slurry prepared by adding a solvent and a binder is coated on both sides of a 20 μm-thick aluminum foil so as to have a thickness of about 100 μm, respectively. Using a powder as a negative electrode active material, about 80 μm
A wound type internal electrode body was prepared using a negative electrode plate prepared by coating so as to have a thickness of μm, and after being housed in a battery case,
It was prepared by filling each of the non-aqueous electrolytes. The battery capacities of these various batteries after the first charge were all about 10 Ah.

The cycle test was performed by setting the charge / discharge cycle shown in FIG. 4 as one cycle and repeating the cycle. That is, in one cycle, a battery in a charged state with a depth of discharge of 50% has a current 10 corresponding to 10 C (discharge rate).
After discharging at 0A for 9 seconds, rest for 18 seconds.
After charging at A for 6 seconds, the battery was charged at 18A for 27 seconds, and the pattern was again set to a 50% charged state. In addition,
The deviation of the depth of discharge in each cycle was minimized by finely adjusting the current value of the second charge (18 A). In order to know the change in the battery capacity during the endurance test, the charge stop voltage 4.1 at a current intensity of 0.2 C is appropriately set.
V, and a discharge stop voltage of 2.5 V, a capacity measurement was performed, and a relative discharge capacity was obtained from a value obtained by dividing the battery capacity at a predetermined cycle number by the initial battery capacity.

As shown in FIG. 3, the test results show that, when at least one of the water extractant and the hydrofluoric acid extractant was added to the non-aqueous electrolyte, the cycle time was lower than that of the battery according to the comparative example. It was confirmed that the characteristics were improved. The cycle characteristics of Example 3 to which both the water extractant and the hydrofluoric acid extractant were added are equivalent to those of Examples 1 and 2,
It is considered that the total amount was the same.

Incidentally, it goes without saying that the above-described lithium secondary battery of the present invention does not matter on the battery structure. Here, in the case of a small-capacity coin battery, since the battery itself is small, it is easy to control the water content by, for example, performing production, storage, and battery assembly of the component in an inert gas atmosphere. However, in producing a large-capacity battery using the above-described wound or laminated internal electrode bodies 1 and 7, for example,
The application of the electrode active material to the current collector substrate also requires the use of a relatively large-scale apparatus, and is performed in the same atmosphere as the outside air even in a room. However, it is practically inconceivable to manufacture in an environment from which moisture is completely removed, in terms of manufacturing costs.

Accordingly, the present invention is suitably adopted for a battery having a large battery capacity, in which water management in the manufacturing process is not easy. Specifically, a wound or laminated internal electrode body 1
・ 7 is suitably used for batteries having a battery capacity of 2 Ah or more. Needless to say, the use of the battery is not limited, but it is particularly suitable for use as a large-capacity battery requiring low internal resistance and excellent cycle characteristics, for driving a motor of an electric vehicle or a hybrid electric vehicle. Can be.

In a battery for driving a motor of an electric vehicle or the like, a large current is required to be discharged when accelerating or climbing a hill, and at this time, the battery temperature rises. But,
When using a non-aqueous electrolyte to which at least one of the water extractant or hydrofluoric acid extractant of the present invention is added,
Even when the battery temperature rises, it is difficult for the extracted water and HF to be released again and dissolved in the non-aqueous electrolyte, so that good cycle characteristics can be maintained.

[0054]

According to the present invention, water and HF in a non-aqueous electrolyte can be efficiently and reliably removed at any time before and after filling a non-aqueous electrolyte into a battery. It is. In particular, moisture absorbed during the assembly of the battery or on the parts dissolves into the non-aqueous electrolyte, thereby removing the moisture contained in the non-aqueous electrolyte after filling in the battery, and the generation of such moisture. There is an advantage that HF can be removed. The present invention provides a water removal effect and H
An excellent effect of improving cycle characteristics, that is, prolonging the life of the battery is achieved by the F removing effect.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the structure of a wound internal electrode body.

FIG. 2 is a perspective view showing a structure of a laminated internal electrode body.

FIG. 3 is a graph showing a cycle test result.

FIG. 4 is a graph showing a charge / discharge pattern in a cycle test.

[Description of Signs] 1 ... wound internal electrode body 2 ... positive electrode plate 3 ... negative electrode plate 4 ...
Separator, 5: electrode lead, 6: electrode lead, 7: laminated internal electrode body, 8: positive electrode plate, 9: negative electrode plate, 10: separator, 11: electrode lead, 12: electrode lead, 13 ...
Core.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Nemoto 2-56, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi Japan F Co., Ltd. F-term (reference) 5H003 AA04 BB05 5H029 AJ05 AK03 AL06 AM01 AM03 AM05 AM07 BJ02 BJ03 BJ14 DJ09

Claims (14)

[Claims] 1. A lithium secondary battery using a non-aqueous electrolyte containing a lithium compound as an electrolyte, wherein a water extractant is added to the non-aqueous electrolyte. . 2. The lithium secondary battery according to claim 1, wherein the water extractant is dissolved in the non-aqueous electrolyte. 3. The lithium secondary battery according to claim 1, wherein the water extractant is an organic phosphorus compound. 4. The lithium secondary battery according to claim 3, wherein the organic phosphorus compound has a P = 0 bond. 5. The lithium secondary battery according to claim 3, wherein the organic phosphorus compound is a phosphoric acid ester or a phosphine oxide. 6. The lithium secondary battery according to claim 1, wherein a hydrofluoric acid extractant is added to the electrolyte. 7. A lithium secondary battery using a non-aqueous electrolyte containing a lithium compound as an electrolyte, wherein a hydrofluoric acid extractant is added to the non-aqueous electrolyte. battery. 8. The lithium secondary battery according to claim 6, wherein the hydrofluoric acid extractant is an organic silicon compound or an organic antimony compound. 9. The lithium secondary battery according to claim 6, wherein the hydrofluoric acid extractant is dissolved in the non-aqueous electrolyte. 10. The lithium secondary battery according to claim 8, wherein the organic silicon compound is a silane. 11. The lithium secondary battery according to claim 1, wherein the lithium compound is lithium hexafluorophosphate. 12. The lithium secondary battery according to claim 1, wherein lithium manganate having a cubic spinel structure containing lithium and manganese as main components is used as the positive electrode active material.
12. The lithium secondary battery according to any one of claims 11 to 11. 13. The lithium secondary battery according to claim 1, wherein the battery capacity is 2 Ah or more. 14. The lithium secondary battery according to claim 1, which is used for an electric vehicle or a hybrid electric vehicle.