JP2001297750A - Power-generating element for lithium secondary battery and lithium secondary battery using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power-generating element and a lithium secondary battery using the same, capable of making a lithium secondary battery with high charging/discharging capacity and a superb cycle performance, and also provide a power-generating element for a lithium secondary battery with high productivity and a lithium secondary battery with high productivity. SOLUTION: With the power-generating element for the lithium secondary battery having a positive electrode with positive electrode active substance as a main ingredient, a negative electrode with a negative electrode active substance as a main ingredient, and a separator, water content of the positive electrode is set to be not more than 260 ppm against Ig of the positive electrode active substance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power generating element for a lithium secondary battery and a lithium secondary battery using the same, and more particularly to a lithium secondary battery having a high charge / discharge capacity and excellent cycle performance. .

[0002]

2. Description of the Related Art In recent years, lithium secondary batteries have been used in mobile phones,
Attention has been paid to a power supply for portable equipment such as a PHS (simple mobile phone) and a small computer, a power supply for power storage, and a power supply for electric vehicles.

[0003] Such a lithium secondary battery generally comprises a positive electrode and a negative electrode capable of releasing and occluding lithium ions at a specific potential, a separator for partitioning the positive electrode and the negative electrode, and a non-aqueous system containing a fluorinated electrolyte. It is composed of an electrolytic solution. Particularly, as the positive electrode, LiCoO ₂ , LiNi
Layered oxides or spinel oxides represented by O ₂ , LiMn ₂ O _{4 and the} like are known, while carbon materials are widely and generally known as negative electrodes.

In the lithium secondary battery having the above-described configuration, the water present in the non-aqueous electrolyte solution has a charge / discharge capacity,
It is considered to be one of the factors that degrade battery characteristics such as cycle performance, self-discharge due to high temperature storage and capacity recovery after storage, and to improve battery performance such as current efficiency and cycle performance of lithium secondary batteries. For the purpose, many proposals have been known in which the amount of water contained in an organic electrolyte (non-aqueous electrolyte) is regulated.

[0005]

However, in recent years, there has been an increasing demand for smaller and lighter devices, such as portable devices, which use a battery as a power source. Batteries are in great demand.
The present invention has been made in view of the above problems, and an object thereof is to provide a power generating element for a lithium secondary battery capable of producing a lithium secondary battery having a high charge / discharge capacity and excellent cycle performance, and An object of the present invention is to provide a used lithium secondary battery. Another object of the present invention is to provide a power generating element for a lithium secondary battery with high productivity and a lithium secondary battery with high productivity.

[0006]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have made intensive studies and as a result, have surprisingly determined the "moisture at the pole" in the power generating element for a lithium secondary battery. In particular, they have found that a lithium secondary battery having a high charge / discharge capacity and excellent cycle performance can be obtained, and the present invention has been achieved.

That is, the present invention provides a lithium secondary battery including a positive electrode having a positive electrode active material as a main component, a negative electrode having a negative electrode active material as a main component, and a separator. In the power generation element for use, the water content of the positive electrode is configured to be 260 ppm or less based on 1 g of the positive electrode active material.

In the power generating element for a lithium secondary battery configured as described above, since the water content of the positive electrode is specified as described above, a lithium secondary battery having a high charge / discharge capacity and excellent cycle performance is provided. Can be made. Further, if the water content of at least the positive electrode satisfies the above-mentioned specification, without performing dehydration operations such as heating and drying more than necessary during the preparation of the positive electrode,
As described above, a power generating element for a lithium secondary battery capable of improving the battery performance of a lithium secondary battery can be manufactured.By using the above-mentioned specification as a production index of a positive electrode, the productivity of the power generating element for a lithium secondary battery can be improved. Can be improved.

Further, according to the present invention, in the power generating element for a lithium secondary battery, the water content of the negative electrode is 10 ppm with respect to 1 g of the negative electrode active material.
It is characterized in that it is configured as follows. In the power generating element for a lithium secondary battery configured as described above, since the water content of the negative electrode is specified as described above, a charge / discharge capacity is extremely high, and a lithium secondary battery with extremely excellent cycle performance is manufactured. it can. Further, if the water content of the negative electrode satisfies the above-mentioned specification, it is possible to further improve the battery performance of the lithium secondary battery as described above without performing dehydration operations such as heating and drying more than necessary at the time of manufacturing the negative electrode. Since a power generation element for a secondary battery can be manufactured, the productivity of the power generation element for a lithium secondary battery can be improved by using the above-mentioned rule as a production index of a negative electrode.

Further, the present inventors have developed a power generation for a lithium secondary battery by using a known binder and a conductive agent in addition to the positive electrode active material and the negative electrode active material as constituent components of the positive electrode and the negative electrode. It has been found that the above object can be achieved by configuring the element. Therefore, the power generating element for a lithium secondary battery according to the present invention is characterized in that the positive electrode and the negative electrode include a conductive agent and a binder as constituent components.

[0011] The lithium secondary battery according to the present invention comprises:
As described in claim 4, a non-aqueous electrolyte containing a fluorinated electrolyte is injected into the power generating element for a lithium secondary battery according to the present invention. As described above, in the power generating element for a lithium secondary battery according to the present invention, the “moisture content of the pole” is defined as described above.
The lithium secondary battery having the configuration described in (1) has a high charge / discharge capacity and is excellent in cycle performance. Further, as described above, since the productivity of the power generating element for a lithium secondary battery is high, the productivity of the lithium secondary battery can be improved.

Further, in the lithium secondary battery according to the present invention, as set forth in claim 5, in the lithium secondary battery, the water content of the non-aqueous electrolytic solution is based on the total weight of the non-aqueous electrolytic solution. Characterized in that it is not more than 20 ppm. In the lithium secondary battery having such a configuration, not only is the “polar water content” of the power generating element for a lithium secondary battery specified as described above, but also the water content of the non-aqueous electrolyte is as described above. , The charge / discharge capacity is extremely high, and the cycle performance is extremely excellent.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

The power generating element for a lithium secondary battery according to the present invention has a positive electrode, a negative electrode, and a separator. The positive electrode has a positive electrode active material as a main component, and the negative electrode has a negative electrode active material. Substances are the main constituent.

Examples of the positive electrode active material, which is a main component of the positive electrode, include LiCoO ₂ , LiNiO ₂ , and LiMn ₂ O _4. Further, LiCoO ₂ , LiNiO ₂ , L
An oxide in which the Co, Ni, and Mn sites of iMn ₂ O ₄ are replaced with other elements can also be used. Such other elements include, for example, Be, B, C, Si, P, Sc, Cu, Z
n, Ga, Ge, As, Se, Sr, Mo, Pd, A
g, Cd, In, Sn, Sb, Te, Ba, Ta, W.G.
Pb, Bi, Co, Fe, Cr, Ni, Ti, Zr, N
b, Y, Al, Na, K, Mg, Ca, Cs, La, C
e, Nd, Sm, Eu, Tb and the like.
C of LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ by a transition metal element such as Ni, Mn, Cr, Fe, Mg, Al
An oxide in which o, Ni, and Mn sites are substituted can be suitably used as a positive electrode active material.

The positive electrode active material is prepared by physically mixing a lithium oxide or lithium salt compound such as lithium carbonate or lithium hydroxide with a manganese oxide or manganese salt compound such as manganese dioxide or manganese nitrate. Or by chemically reacting at room temperature or high temperature and under normal pressure or high pressure, paste, mixed salt,
Alternatively, they are suitably produced by generating precipitates and subsequently firing them stepwise.

Examples of the negative electrode active material, which is a main component of the negative electrode, include a carbon material capable of inserting and extracting lithium, and particularly a plane spacing (d) estimated by an X-ray diffraction method.
002) is preferably 0.3354 to 0.3369 nm, and carbon particles having a crystal size (Lc) of 20 nm or more in the c-axis direction are preferred.

Although the positive electrode active material and the negative electrode active material have been described in detail above, it is preferable that the positive electrode and the negative electrode are formed using a conductive agent and a binder in addition to the above-mentioned active material which is a main component. preferable.

The conductive agent is not limited as long as it is an electron conductive material which does not adversely affect battery performance.
Natural graphite (flaky graphite, flaky graphite, earthy graphite, etc.), artificial graphite, carbon black, acetylene black, ketjen black, carbon whisker, carbon fiber, metal (copper, nickel, aluminum, silver, gold, etc.) powder, A conductive material such as a metal fiber or a conductive ceramic material can be included as one type or a mixture thereof. Among these, acetylene black is desirable as the conductive agent from the viewpoint of conductivity and coatability. The amount of the conductive agent to be added is preferably 1 to 50% by weight, and particularly preferably 2 to 30% by weight, based on the total weight of the positive electrode or the negative electrode. These mixing methods are physical mixing, and ideally, uniform mixing. Therefore, a powder mixer such as a V-type mixer, an S-type mixer, a grinder, a ball mill, and a planetary ball mill can be mixed in a dry or wet manner.

Examples of the binder include thermoplastic resins such as polytetrafluoroethylene, polyvinylidene fluoride, polyethylene and polypropylene, ethylene-propylene diene terpolymer (EPDM), and sulfonated EPD.
M, a polymer having rubber elasticity such as styrene-butadiene rubber (SBR) or fluororubber, or a polysaccharide such as carboxymethylcellulose can be used alone or as a mixture of two or more. Further, it is desirable that a binder having a functional group that reacts with lithium, such as a polysaccharide, be deactivated by, for example, methylation. The amount of the binder added is 1 to the total weight of the positive electrode or the negative electrode.
It is preferably 50% by weight, particularly preferably 2 to 30% by weight.

A positive electrode and a negative electrode can be suitably manufactured by kneading a positive electrode active material or a negative electrode active material, a conductive agent, and a binder in an organic solvent such as toluene, forming an electrode shape, and drying. Here, in the present invention,
In the preparation of the positive electrode, the drying is performed such that the water content of the positive electrode is 260 ppm or less based on 1 g of the positive electrode active material. In the preparation of the negative electrode, the drying is preferably performed so that the water content of the negative electrode is 10 ppm or less based on 1 g of the negative electrode active material.

The drying is carried out, for example, by drying the kneaded material under reduced pressure using a known vacuum dryer, and drying conditions such as temperature and time are set so as to satisfy the above-mentioned requirements.

As the separator of the power generating element for a lithium secondary battery according to the present invention, an insulating thin film having excellent ion equivalentity and mechanical strength can be used. Sheets, microporous membranes, nonwoven fabrics and cloths made of olefin polymers such as polypropylene and polyethylene, glass fibers, polyvinylidene fluoride, polytetrafluoroethylene and the like are used because of their resistance to organic solvents and hydrophobicity. The pore size of the separator is in a range generally used for a battery, and is, for example, 0.01 to 10 μm. The same applies to the thickness, which is in the range generally used for batteries, for example, 5 to 300 μm.

As described above, the positive electrode, the negative electrode,
The power generating element for a lithium secondary battery according to the present invention having a separator is configured such that the water content of the positive electrode is 260 ppm or less based on 1 g of the positive electrode active material. By using the lithium secondary battery, a lithium secondary battery having high charge / discharge capacity and excellent cycle performance can be manufactured. Further, as long as the water content of the positive electrode satisfies the above-mentioned specification, in the desolvation step at the time of producing the positive electrode, even if the dehydration operation such as heating and drying is not performed more than necessary, the battery performance of the lithium secondary battery can be improved as described above. Since the power generation element for a lithium secondary battery can be manufactured, the productivity of the power generation element for a lithium secondary battery can be improved by using the above-mentioned specification as a production index of the positive electrode.

Further, as described above, the power generating element for a lithium secondary battery according to the present invention is configured such that the water content of the negative electrode is 10 ppm or less based on 1 g of the negative electrode active material. By using the power generating element for a lithium secondary battery, a lithium secondary battery having extremely high charge / discharge capacity and extremely excellent cycle performance can be manufactured. Further, if the water content of the negative electrode satisfies the above-mentioned specification, the battery performance of the lithium secondary battery can be improved as described above without performing dehydration operations such as heating and drying more than necessary in the desolvation step in preparing the negative electrode. Since a power generation element for a lithium secondary battery that can be improved can be manufactured, the productivity of the power generation element for a lithium secondary battery can be improved by using the above-mentioned specification as a production index of the negative electrode.

As an embodiment of the power generating element for a lithium secondary battery according to the present invention, a configuration in which a positive electrode and a negative electrode are closely adhered via a separator can be exemplified. Further, for example, when a positive electrode, a negative electrode, and a separator are individually stored in respective storage portions of a battery package having a positive electrode storage portion, a negative electrode storage portion, and a separator storage portion, for example, when a coin-type battery is manufactured. In this case, the assembly including the positive electrode, the negative electrode, and the separator is one embodiment of the power generating element for a lithium secondary battery according to the present invention.

The lithium secondary battery according to the present invention includes the power generating element for a lithium secondary battery according to the present invention described in detail above,
It is produced by injecting a non-aqueous electrolyte containing a fluorinated electrolyte.

Examples of the fluorinated electrolyte include LiPF ₆ , LiBF ₄ and LiAsF exhibiting high lithium ion conductivity.
₆ , LiOSO ₂ CF ₃ is preferably used. These fluorinated electrolytes are usually contained in a non-aqueous electrolyte at 0.1 M to 3.0 M.
M, preferably from 0.5M to 2.0M.

The fluorinated electrolyte is preferably used as a non-aqueous electrolyte in combination with a high dielectric constant solvent and a low viscosity solvent. Examples of the high dielectric constant solvent include ethylene carbonate (EC) and propylene carbonate (P
Cyclic carbonates such as C) are preferred. These high dielectric constant solvents may be used alone or in combination of two or more. Examples of the low-viscosity solvent include dimethyl carbonate (DMC),
Chain carbonates such as methyl ethyl carbonate (MEC) and dimethyl carbonate (DMC), tetrahydrofuran (THF), 2-methyltetrahydrofuran,
1,4-dioxane, 1,2-dimethoxyethane, 1,2
Ethers such as -diethoxyethane and 1,2-dibutoxyethane, lactones such as γ-butyrolactone, nitriles such as acetonitrile, amides such as dimethylformamide, and esters such as methyl formate and methyl acetate. . These low viscosity solvents may be used alone or in combination of two or more.

Further, the water content of the non-aqueous electrolyte is preferably 20 ppm or less based on the total weight of the non-aqueous electrolyte. As described above, not only the "polar water content" of the power generating element for a lithium secondary battery is specified as described above, but also the water content of the non-aqueous electrolyte is specified, so that the charge / discharge capacity is extremely high, A lithium secondary battery having extremely excellent cycle performance can be manufactured.

In the lithium secondary battery according to the present invention, for example, a power generating element for a lithium secondary battery in which a positive electrode and a negative electrode are closely adhered via a separator is placed in a battery package.
Next, a non-aqueous electrolytic solution is injected into the battery package, and finally sealed. Further, as described above, the positive electrode, the negative electrode, and the separator are individually stored in the respective storage portions of the battery package having the positive electrode storage portion, the negative electrode storage portion, and the separator storage portion. It may be obtained by injecting an electrolytic solution and finally sealing.

The battery package includes a current collector for the positive electrode that can be in close contact with the positive electrode and a current collector for the negative electrode that can be in close contact with the negative electrode when the power generating element for a lithium secondary battery is loaded in the battery package. Preferably, for example, as the current collector for the positive electrode, aluminum, titanium, stainless steel, nickel, calcined carbon, conductive polymer, conductive glass, and the like, adhesive, conductive and For the purpose of improving oxidation resistance, a material obtained by treating the surface of aluminum, copper, or the like with carbon, nickel, titanium, silver, or the like can be used. As the current collector for the negative electrode, copper, nickel, iron, stainless steel, titanium, aluminum, calcined carbon, conductive polymer, conductive glass, Al-Cd alloy, etc.
For the purpose of improving conductivity and oxidation resistance, a material obtained by treating the surface of copper or the like with carbon, nickel, titanium, silver, or the like can be used. These materials can be oxidized on the surface.

Regarding the shape of the current collector, in addition to a foil shape, a film shape, a sheet shape, a net shape, a punched or expanded material, a lath body, a porous body, a foamed body, a formed body of a fiber group, and the like are used. Can be There is no particular limitation on the thickness.
〜500 μm is used. Among these current collectors, as the current collector for the positive electrode, an aluminum foil having excellent oxidation resistance is used, and as the current collector for the negative electrode, the aluminum foil is stable in a reduction field, and has excellent conductivity, and is inexpensive. It is preferable to use a copper foil, a nickel foil, an iron foil, and an alloy foil including a part thereof. Furthermore, the rough surface roughness is 0.2 μmR
It is preferable that the thickness of the foil be equal to or larger than “a”, whereby the adhesion between the positive electrode and the negative electrode and the current collector becomes excellent. Therefore, it is preferable to use an electrolytic foil because of having such a rough surface. In particular, an electrolytic foil subjected to a napping treatment is most preferable.

The lithium secondary battery according to the present invention, which can be manufactured as described above, has a high charge / discharge capacity because the “polar water content” in the power generating element for a lithium secondary battery is specified as described above. Excellent cycle performance. Also,
As described above, since the productivity of the power generation element for a lithium secondary battery is high, the productivity of the lithium secondary battery can also be improved.

[0035]

The present invention will be described in detail below with reference to examples and comparative examples, but these are not intended to limit the present invention. (Example 1) "Preparation of positive electrode active material" Lithium acetate dihydrate and manganese (II) acetate tetrahydrate were mixed such that the element ratio of lithium and manganese was 1.10: 1.90. This mixture was dissolved in acetic acid. The mixture was stirred while applying heat, and acetic acid was evaporated from the completely dissolved solution to obtain a mixed salt. This mixed salt is temporarily calcined at 500 ° C. for 12 hours,
The main baking was performed at 0 ° C. for 24 hours. The obtained fired product is crushed,
X-ray diffraction measurement (XRD measurement) of the pulverized product confirmed the formation of lithium manganate having a spinel structure.

[Preparation of Positive Electrode] Lithium manganate as the positive electrode active material prepared as described above, acetylene black as a conductive agent, and polytetrafluoroethylene powder as a binder were mixed at a weight ratio of 85:10. : 5, and kneaded with toluene. This was formed into a 0.8 mm thick sheet by a roller press. Next, this was punched out into a circle having a diameter of 16 mm and dried at 150 ° C. for 10 hours under a reduced pressure of 26.7 Pa.

[Method of Measuring Moisture Content] To measure the moisture content of the electrode, a coulometric titration moisture meter CA-0 manufactured by Mitsubishi Kasei Corporation was used.
Type 6 was used. 220 ° C under nitrogen atmosphere by gas phase method
Was determined by the Karl Fischer method. As a result, the water content of the positive electrode was calculated to be 256 ppm based on 1 g of the positive electrode active material.

[Preparation of Negative Electrode] Artificial graphite as an active material for negative electrode (average particle size: 6 μm, plane spacing (d _{00 2} ) by X-ray diffraction method)
Is 0.337 nm, and the crystal size in the C-axis direction (Lc)
Was 55 nm) and polytetrafluoroethylene powder in a weight ratio of 95: 5, and toluene was added and kneaded sufficiently. This was formed into a sheet having a thickness of 0.1 mm by a roller press. Next, this was punched out into a circle having a diameter of 16 mm, and dried at 150 ° C. for 15 hours under a reduced pressure of 26.7 Pa. According to the above "method of measuring water content", the water content of the negative electrode was calculated to be 10 ppm based on 1 g of the negative electrode active material.

"Preparation of non-aqueous electrolyte containing fluorinated electrolyte" LiPF ₆ as a fluorinated electrolyte was dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1 so as to be 1 mol / l. Thus, an electrolytic solution was prepared. If the water content of the non-aqueous electrolyte is large,
The reaction between water and LiPF ₆ tends to generate free hydrogen fluoride (HF), and the concentration of the hydrogen fluoride may fluctuate over time, thereby deteriorating battery characteristics such as charge / discharge capacity and cycle performance. Therefore, all of the examples are 2
A liquid of 0 ppm or less was used.

[Preparation of power generating element for lithium secondary battery and lithium secondary battery using the same] In a dry atmosphere having a dew point of −50 ° C. or less, a positive electrode can having an aluminum foil as a positive electrode current collector (a positive electrode housing) Part) and a negative electrode can (anode storage part) having a copper foil as a negative electrode current collector. Further, a separator (polyolefin-based porous film) was housed in a coin-type battery package so as to prevent the close contact between the positive electrode and the negative electrode, thereby producing a power generating element for a lithium secondary battery. Subsequently, the non-aqueous electrolyte prepared by the above method was poured into a coin-type battery package to have a diameter of 20 mm and a thickness of 1.
A lithium secondary battery of Example 1 having a coin shape of 6 mm was produced.

"Charging / discharging test" The end-of-charge voltage was set to 4.2 V,
A constant current charge / discharge was performed under the conditions of a discharge end voltage of 3.0 V, a charge / discharge current of 1 mA, and a test temperature of 25 ° C. The charge and discharge capacities in the first cycle were 112.8 mAh / g and 96.2 mAh / g, respectively, in terms of the positive electrode active material.
When the number of cycles at the time when the discharge capacity was reduced to 60% of the initial value was measured as the cycle performance, it was 110 cycles.

Example 2 The positive electrode was 26.7 Pa, 170
A negative electrode, a non-aqueous electrolytic solution and a separator were used, which were the same as those used in the lithium secondary electric field of Example 1 except that they were manufactured by drying under reduced pressure at 10 ° C. for 10 hours. Then, a lithium secondary battery of Example 2 was produced. The water content of the positive electrode in the electrode group of the lithium secondary electric field is
It was 45 ppm based on 1 g of the positive electrode active material. Example 1
When the charge / discharge test was performed in the same manner as in the above, the initial charge amount and the initial discharge amount were 113.0 mAh / g and 96.1, respectively.
mAh / g. The cycle performance was 181.

Example 3 The positive electrode was 26.7 Pa, 190
A negative electrode, a non-aqueous electrolytic solution and a separator were used, which were the same as those used in the lithium secondary electric field of Example 1 except that they were manufactured by drying under reduced pressure at 10 ° C. for 10 hours. Then, a lithium secondary battery of Example 3 was produced. The water content of the positive electrode in the electrode group of the lithium secondary electric field is
It was 45 ppm based on 1 g of the positive electrode active material. Example 1
When the charge / discharge test was performed in the same manner as in the above, the initial charge amount and the initial discharge amount were 112.9 mAh / g and 96.1, respectively.
mAh / g. The cycle performance was 179.

(Comparative Example 1) A positive electrode of 26.7 Pa, 120
The same positive electrode, non-aqueous electrolyte and separator as used in the lithium secondary electric field electrode group used in the lithium secondary electric field of Comparative Example 1 were used except that they were manufactured by drying under reduced pressure at 10 ° C. for 10 hours. Then, a lithium secondary battery of Comparative Example 1 was produced. The water content of the positive electrode in the electrode group of the lithium secondary electric field is
It was 509 ppm with respect to 1 g of the positive electrode active material. When a charge / discharge test was performed in the same manner as in Example 1, the initial charge amount and the initial discharge amount were 103.9 mAh / g and 88.
It became 3 mAh / g. The cycle performance was 120.

(Comparative Example 2) A positive electrode was used at 26.7 Pa, 100
By using the same positive electrode, non-aqueous electrolyte and separator as in the electrode group of the lithium secondary electric field used for the lithium secondary electric field of Comparative Example 2 except that the electrode was dried under reduced pressure at 10 ° C. for 10 hours. A lithium secondary battery of Comparative Example 2 was produced. The water content of the positive electrode in the electrode group of the lithium secondary electric field is
It was 687 ppm based on 1 g of the positive electrode active material. When a charge / discharge test was performed in the same manner as in Example 1, the initial charge amount and the initial discharge amount were 102.6 mAh / g and 87.
It became 2 mAh / g. The cycle performance was 150.

Table 1 summarizes the results of the above charge / discharge test.

[0047]

[Table 1]

As can be seen from the evaluation results of the lithium batteries of Examples 1 to 3 and Comparative Examples 1 and 2, the drying temperature conditions at the time of manufacturing the positive electrode were 100 ° C., 120 ° C., 150 ° C., 170 ° C.
As the temperature rose to ° C., the water content of the positive electrode decreased, and tended to be constant (45 ppm / g-active material) at higher drying temperatures. The amount of water in the positive electrode was 1 g of the positive electrode active material.
, The values indicating the initial charge capacity, the initial discharge capacity, and the cycle performance increase, and when the water content of the positive electrode is 260 ppm or less, 1
The values tended to be stabilized at high values of around 180 mAh / g around 13 mAh / g and around 96 mAh / g. Thus, the battery characteristics (initial charge capacity,
It was clarified from the above Examples and Comparative Examples that the boundary of the first discharge capacity and the cycle performance) existed.

Example 4 The negative electrode was 26.7 Pa, 170
By using the same positive electrode, non-aqueous electrolyte solution and separator as in the electrode group of the lithium secondary electric field used in Example 1 except that it was manufactured by drying under reduced pressure at 10 ° C. for 10 hours. Then, a lithium secondary battery of Example 4 was produced. The water content of the negative electrode in the electrode group of the lithium secondary electric field is
It was 7 ppm with respect to 1 g of the negative electrode active material. When a charge / discharge test was performed in the same manner as in Example 1, the initial charge amount and the initial discharge amount were 112.8 mAh / g and 96.2 m, respectively.
Ah / g. The cycle performance was 180.

(Example 5) A negative electrode of 26.7 Pa, 120
By using the same positive electrode, non-aqueous electrolyte solution and separator as in the electrode group of the lithium secondary electric field used in Example 1 except that it was manufactured by drying under reduced pressure at 10 ° C. for 10 hours. Then, a lithium secondary battery of Example 5 was produced. The water content of the negative electrode in the electrode group of the lithium secondary electric field is
It was 28 ppm with respect to 1 g of the negative electrode active material. Example 1
When the charge / discharge test was performed in the same manner as in the above, the initial charge amount and the initial discharge amount were 103.4 mAh / g and 87.9, respectively.
mAh / g. The cycle performance was 160.

Example 6 A negative electrode was used at 26.7 Pa, 100
By using the same positive electrode, non-aqueous electrolyte solution and separator as in the electrode group of the lithium secondary electric field used in Example 1 except that it was manufactured by drying under reduced pressure at 10 ° C. for 10 hours. Then, a lithium secondary battery of Example 6 was produced. The water content of the negative electrode in the electrode group of the lithium secondary electric field is
It was 38 ppm with respect to 1 g of the negative electrode active material. Example 1
When the charge / discharge test was performed in the same manner as in the above, the initial charge amount and the initial discharge amount were 103.9 mAh / g and 88.3, respectively.
mAh / g. The cycle performance was 160.

Table 2 summarizes the results of the charge / discharge tests of the lithium secondary batteries of Examples 4 to 6.

[0053]

[Table 2]

As can be confirmed from the evaluation results of the lithium batteries of Examples 1 and 4 to 6, the water content of the negative electrode was
g, the values indicating the initial charge capacity, the initial discharge capacity, and the cycle performance increase, and when the water content of the negative electrode is 10 ppm or less, each of the values increases to 11 ppm.
There was a tendency to stabilize at a high value of 180 around 3 mAh / g, around 96 mAh / g. As described above, it is clear from the above Examples that the boundary of the battery characteristics (initial charge capacity, initial discharge capacity, cycle performance) exists near the water content of the negative electrode of 10 ppm. That is, in addition to the fact that the water content of the positive electrode is 260 ppm or less based on 1 g of the positive electrode active material and the water content of the negative electrode active material is 10 ppm or less based on 1 g of the negative electrode active material, the battery characteristics of the lithium secondary battery ( Initial charge capacity, initial discharge capacity, cycle performance)
Was confirmed to be extremely high. The decrease in the initial charge capacity and the initial discharge capacity with the increase in the water content of the negative electrode is due to the fact that the thickness of the nonconductive film generated on the negative electrode increases the resistance at the electrode interface, causing an IR drop. It is presumed that the decrease in cycle performance is caused by the fact that the water gradually dissolved in the electrolyte gradually accumulates as a film on the negative electrode.

Further, from the above results, the "moisture content of the poles"
If the electrode is manufactured so as to satisfy the above-mentioned rules, in the step of desolvation, lithium can be used to improve the battery performance of the lithium secondary battery as described above without performing dehydration operations such as heating and drying more than necessary. Since a power generation element for a secondary battery can be manufactured, it has also been confirmed that the productivity can be improved for the power generation element for a lithium secondary battery and a lithium secondary battery using the same by using the above-mentioned rules as extreme production indexes.

[0056]

According to the power generating element for a lithium secondary battery according to the present invention, as set forth in claim 1, in the power generating element for a lithium secondary battery, the water content of the positive electrode is 1 g of the positive electrode active material. Therefore, it is possible to provide a power generating element for a lithium secondary battery capable of producing a lithium secondary battery having high charge / discharge capacity and excellent cycle performance. Further, if the water content of at least the positive electrode satisfies the above-mentioned specification, the battery performance of the lithium secondary battery can be improved without performing dehydration operations such as heating and drying more than necessary at the time of manufacturing the positive electrode. By using the production index, a power generating element for a lithium secondary battery with high productivity can be provided.

According to the power generation element for a lithium secondary battery according to the present invention, as set forth in claim 2, in the power generation element for a lithium secondary battery, the water content of the negative electrode is 1 g of the negative electrode active material. Therefore, it is possible to provide a power generation element for a lithium secondary battery capable of producing a lithium secondary battery having extremely high charge / discharge capacity and extremely excellent cycle performance. Further, if the water content of the negative electrode satisfies the above-mentioned specification, the battery performance of the lithium secondary battery can be further improved without performing unnecessary dehydration operations such as heating and drying at the time of manufacturing the negative electrode. By using the production index, a power generating element for a lithium secondary battery with high productivity can be provided.

According to the power generating element for a lithium secondary battery according to the present invention, as described in claim 3, as a constituent of the positive electrode and the negative electrode, a known binder and a current collector can be used. A power generation element for a secondary battery can be provided.

According to the lithium secondary battery of the present invention, as described in claim 4, the non-aqueous electrolytic solution containing a fluorinated electrolyte in the power generating element for a lithium secondary battery according to the present invention. And the “polar water content” of the power generating element for a lithium secondary battery is specified as described above, so that a lithium secondary battery having high charge / discharge capacity and excellent cycle performance can be provided. . Further, since the productivity of the power generation element for a lithium secondary battery is high, a lithium secondary battery with high productivity can be provided.

Further, according to the lithium secondary battery of the present invention, as set forth in claim 6, in the lithium secondary battery, the water content of the non-aqueous electrolyte is reduced by the total weight of the non-aqueous electrolyte. Therefore, a lithium secondary battery having extremely high charge / discharge capacity and extremely excellent cycle performance can be provided.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Shutake Huang 2-3-1-21, Kosobe-cho, Takatsuki-shi, Osaka Inside Yuasa Corporation Co., Ltd. (72) Hiroshi Yufu, 2-3-3 Kosobe-cho, Takatsuki-shi, Osaka No. 21 F-term in Yuasa Corporation (reference) 5H029 AJ03 AJ05 AK03 AL06 AM03 AM04 AM05 AM06 AM07 BJ03 DJ07 DJ08 5H050 AA07 AA08 BA17 CA08 CA09 CB07 DA10 DA11

Claims (5)

[Claims] 1. A power generation element for a lithium secondary battery having a positive electrode having a positive electrode active material as a main component, a negative electrode having a negative electrode active material as a main component, and a separator, wherein the water content of the positive electrode is 26 for 1 g of positive electrode active material
A power generation element for a lithium secondary battery, wherein the power generation element is configured to be 0 ppm or less. 2. The method according to claim 1, wherein the water content of the negative electrode is less than the negative electrode active material.
The power generation element for a lithium secondary battery according to claim 1, wherein the power generation element is configured to be 10 ppm or less with respect to g. 3. The power generating element for a lithium secondary battery according to claim 1, wherein the positive electrode and / or the negative electrode include a conductive agent and a binder as constituent components. 4. A lithium secondary battery, wherein a non-aqueous electrolyte containing a fluorinated electrolyte is injected into the power generating element for a lithium secondary battery according to claim 1. . 5. The lithium secondary battery according to claim 4, wherein the non-aqueous electrolyte has a water content of 20 ppm or less based on the total weight of the non-aqueous electrolyte. .